Filming nanodroplet running and jetting mediated by nanoscale solid-gas and solid-liquid interface

Filming nanodroplet running and jetting mediated by nanoscale solid-gas and solid-liquid interface | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Filming nanodroplet running and jetting mediated by nanoscale solid-gas and solid-liquid interface Bin Chen, Linfeng Xu, Zetan Cao, Zhiwen Liu, Cheng Zheng, Simin Peng, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4865225/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 17 Apr, 2025 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract Nanodroplets at multiphase interfaces are ubiquitous in nature with implications ranging from fundamental interfacial science to industrial applications including catalytic, environmental, biological and medical processes. Direct observation of the full dynamic evolutions of liquid metal nanodroplets at nanoscale multiphase interfaces offers indispensable insights, however, remains challenging and unclear at the moment. Here, we have fabricated massive ready-to-use gas and liquid cells containing HgS nanocrystals through electrospinning and achieved the statistical investigations of full picture of Hg nanodroplets evolving at solid-gas and solid-liquid interfaces by in-situ transmission electron microscopy. Upon the electron-beam excitation of HgS in the gas cells, the voids nucleated, grew and then coalesced into the crack-like feature preferentially along the direction through the bridges. Meanwhile, the Hg nanodroplets formed, moved rapidly on the ratchet surface with the velocity of several tens of nm/s and were finally evolved into bigger ones through the nanobridges with the relatively large gap of ~ 6 nm. Distinctly and surprisingly, mediated by the solid-liquid interface at nanoscale, the liquid Hg with the ink-like feature jetted in the liquid cells. Such ink-jetting behavior would occur multiple times with the intervals from several to several tens of seconds, which was modulated through the competition between the reductive electrons and the oxidative species derived from the radiolysis of liquid by the electron-beam. In-depth understanding of distinct nanodroplets dynamics at nanoscale solid-gas and solid-liquid interfaces offers a feasible approach of designing liquid metal-based nanocomplexes with regulatory interfacial, morphological and rheological functionalities. Physical sciences/Chemistry/Physical chemistry/Reaction kinetics and dynamics Physical sciences/Physics/Chemical physics Metal nanodroplets Interfaces In-situ characterization Liquid cell Structural dynamics Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction An interface refers to the contact boundary plane, separating two phases that are chemically and/or structurally distinct, each of which may be solid, liquid or gaseous. The ubiquitous interfaces play a vital role in determining the properties and processing of almost all materials, which have promoted great interest in areas including catalysis 1 , electrochemistry 2 , nucleation and growth 3 , batteries 4 , optoelectronics 5 , and biological reactions 6 . For example, a thin liquid-like layer can serve as an intermediate for the mass transport from metal nanoparticles (NPs) to the liquids, differing from the traditional transfer behavior 7 . Similarly, the hot electron transfer has been found to be faster at the solid − liquid interfaces than that at the solid − gas ones in the Pt/n-Si system 8 . The oxidation of isopropyl alcohol to acetone catalyzed by platinum has been reported to be enhanced at the solid/liquid interfaces upon comparison with that at the solid/gas ones 9 , while the enhancement in the oxidation of alloys (e.g., nickel–chromium) occurs with the existence of water-vapor interfaces compared to that of pure oxygen 10 . Similar increment of etching rates has been observed in the solid–liquid–gas interfaces formed at the gold nanorods in liquids with the assistance from the adsorbed oxygen 11 . Despite the aforementioned progress achieved in the leading materials with the solid form, the behaviors of liquid nanodroplets at different interfaces have been relatively less reported and understood. Unraveling the fundamental physicochemical processes of interfacial liquid droplets offer unique and promising applications in the fields including nanoreactors 12 , microfluidics 13 , nanomotors 14 , nanotransporters 15 , 3D additive manufacturing 16 , nanowelding 17 , nanowetting 18 , spraying 19 , and flexible/wearable devices 20 . It has been shown that the motion velocities of water microdroplets are increased dramatically on the superhydrophobic interfaces 21 , and the chemical reactions can be also facilitated on the surface of liquid droplets 22 as well as the solid-liquid interfaces 23,24 . Moreover, the introduction of additional gradient external fields including electric force, temperature, light and surface free energy would further modulate the dynamical processes of droplets. For instance, the water droplets demonstrate the exceptional uphill motion through tuning the gradient surface energy caused by the interfacial morphologies 25 . Nevertheless, the full picture of nanoscale droplets dynamics from initial formation to subsequent evolution as well as the simultaneous structural/elemental identification remains challenging and unclear, leading to the isolated understanding and even uncertainty in the results. Therefore, direct visualization of the whole evolution of nanodroplets with in-situ capability is indispensable, which enables a thorough understanding of fundamental interfacial processes at complex multiphase boundaries (e.g., solid–liquid–gas and solid–liquid–liquid), and further manipulation of the interfacial behaviors at the nanoscale. Herein, using our previously developed massive cell fabrication method 26 , we successfully encapsulated the HgS nanocrystals (NCs) in gas and liquid environments, and statistically investigated the full evolution dynamics of less-known metal nanodroplets (Hg) at nanoscale solid-gas and solid-liquid interfaces by in-situ transmission electron microscopy (TEM). The choice of HgS as the studied system was based on the following considerations: i) Facile formation of metal Hg nanodroplets from HgS upon the electron-beam (e-beam) excitation so that the full dynamics from the initial formation (birth) to the later evolutions were allowed; ii) HgS NCs were water soluble, leading to the easy preparation of liquid cells; and iii) Nanoscale saw-tooth morphology of HgS NCs enabled the investigations of motion behavior of the Hg nanodroplets. In the gas cells, the nucleation, growth and coalescence of the voids were observed, while simultaneously the Hg nanodroplets occurred, then moved rapidly on the ratchet surface, and finally coalesced into the large ones through the bridges. Interestingly, in the case of liquid cells, the ink-like liquid Hg jetted from the solid-liquid (HgS-water) interface. Determined by the competition between the reductive electrons and the oxidative species derived from the radiolysis of liquid, consecutive ink-jetting behavior happened with the interval time between two neighboring ones in the range from several to several tens of seconds. Further ex-situ control experiments verified the above behaviors. The underlying mechanisms for the above phenomena were thoroughly discussed. Results Structural characteristics of HgS for gas/liquid cell studies Chiral α-HgS NCs were prepared by the seed-mediated epitaxial growth technique, as detailed in Methods section. Figure 1 a shows the helical arrangement of Hg and S atoms along the crystallographic c axis in HgS with the P 3 1 21 space group, which represents an atomic-scale primary chiral unit. Figure 1 b shows the as-synthesized NCs with the length and width of ~ 120 nm and 60 nm. The measured interplanar spacing of 3.359 Å in high-resolution TEM corresponds to the (101) plane of α-HgS that is indicated from the diffraction pattern (Fig. 1 b, inset). The chirality of the NCs would be tuned through the enantioselective synthesis strategy, where an example is demonstrated in Fig. 1 c. Using the massive cell fabrication method developed recently, we have succeeded in encapsulating the HgS NCs in gas and liquid environments for later dynamics studies. The structural evolution of the HgS nanostructures in gas and liquid is visualized by in-situ TEM (Fig. 1 d). An electron beam (e-beam) is utilized to excite the NCs, while simultaneously the structural information involved during the dynamical processes is recorded by a digital camera in real-time. The schematic diagram of the gas/liquid cell is illustrated in Fig. 1 e (top). The difference in fabrication was due to the addition of the glycerol (retard the volatilization of water) into the core liquid precursor during electrospinning of the liquid cells. Figure 1 e (bottom) presents a typical TEM image of the as-prepared cell with a HgS NC inside. With the e-beam excitation, a certain number of dark clusters (marked in the area A) were steadily formed on the NC (Fig. 1 f, top). The dark clusters were composed of Hg nanodroplets, which were verified by the energy dispersive X-ray spectroscopy (EDS). When the HgS NC located in vacuum (without the isolation by the cell), however, only the morphological framework remained after the long-term e-beam irradiation because of the evaporation of Hg droplets (Fig. 1 f, bottom). The EDS analysis suggested that the remaining white feature (marked in the area B) was almost from S, verifying the evaporation of Hg. Structural evolution of HgS NCs in gas cell Figure 2 shows a series of TEM images depicting the nucleation and growth dynamics of Hg nanodroplets in the gas cell (see Supplementary Movie 1 for details). Herein, for the sake of convenience, the time zero (0 s) was defined as the moment of initiating the video recording (the initial TEM alignment was operated under a low dose rate of ~ 50 e/Å 2 ·s so that the structural evolution was not excited). At a high dose rate of 3240 e/Å 2 ·s (Fig. 2 a), abundant voids (white features marked by the rectangles) arose rapidly, accompanied with the appearance of Hg nanodroplets (marked by the circles) after e-beam excitation for 2 s. As the irradiation time elapsed (e.g., 15 and 19 s), the voids wriggled and coalesced when they met. The voids grew up after coalescence (Fig. 2 b, a typical example given at 270 s), and later turned into a crack-like feature at 380 s (marked by the rectangle) through lengthening (310 s) and coalescence processes (365 s). Different from the phenomenon observed in vacuum 27 , the small Hg nanodroplets gradually grew up during the e-beam excitation. Upon comparison of the TEM images at 410 s and 720 s (Fig. 2 c, indicated by the arrows), it showed that the Hg nanodroplets were further enlarged to a size of approximately 10–15 nm due to the coalescence. At this stage, the droplets became relatively stable. When the dose rate was further increased to 7350 e/Å 2 ·s, however, the Hg nanodroplets moved again and became larger at 1150 s. Ultimately, a big and stable nanodroplet with a size of ~ 70 nm appeared at 1250 s (the inset was a view of the whole HgS morphology), which was much larger than that observed in vacuum (typically 5–7 nm in size). The dynamical evolutions of the voids and Hg nanodroplets are schematically illustrated in the rightmost column of the figure. Rather than the enlargement of Hg nanodroplets inside the gas cells, we also noted that the big nanodroplets could suddenly fade away if the cells were broken intentionally. As depicted in Supplementary Fig. 1, the Hg nanodroplets gradually grew as the irradiation time elapsed and had a size of ~ 40 nm at 480 s. These nanodroplets suddenly began to fade away from 480 s, and almost disappeared at 515 s. Such evaporation and disappearance of the nanodroplets was similar to that observed in the vacuum condition 27 , which was due to the structural breakage of the gas cell that became vacuum environment in the TEM chamber. Detailed Evolution of voids and Hg droplets in gas cell To gain detailed insight into the dynamical behavior of voids and Hg droplets, the dose rate-dependent experiments were carried out, as depicted in Fig. 3 . As the dose rate was increased from 2020 to 7310 e/Å 2 ·s, the stable size of Hg droplets increased from ~ 1.6 to 40.7 nm (Fig. 3 a). It indicates that Hg droplets would stabilize with an appropriate size at each specific dose rate and higher dose rate facilitated the formation of larger droplets in the closed gas cell. The growth speed of Hg nanodroplets was estimated to be from ~ 0.004 nm/s to 0.162 nm/s when the dose rate was increased from 2020 to 4810 e/Å 2 ·s (inset of Fig. 3 a). Figure 3 b shows the distribution characteristics of Hg and S elements as a function of the dose rate. Five different areas were selected to analyze the elemental distribution of the samples after the e-beam irradiation (an example was given in the inset of Fig. 3 b), revealing the diffusion behavior of Hg nanodroplets. Upon comparison of Hg/S ratio at different dose rates, large variation was observed under the high dose rate, which was due to the random distribution of fewer Hg droplets with relatively big size (refer to the TEM image at 1150 or 1250 s in Fig. 2 ). The movement speeds of voids and Hg droplets at different dose rates were then quantitatively estimated, as presented in Fig. 3 c. In the case of voids, the rate of movement increased from ~ 0.19 to 5.04 nm/s with the enhancement of dose rate from 688 to 3520 e/Å 2 ·s (inset of Fig. 3 c). Similarly, the Hg nanodroplets exhibited the movement speed from ~ 0.08 to 2.91 nm/s with the increment of dose rate from 1060 to 3520 e/Å 2 ·s. As the dose rate was further increased to a higher level (4340 e/Å 2 ·s), the Hg nanodroplets moved much faster and had a velocity of ~ 55.94 nm/s. Finally, they would reach the velocity of 65.14 nm/s under the dose rate of 7340 e/Å 2 ·s. We noticed that the voids and Hg droplets grew after coalescence, which were detailed in Supplementary Movies 2 and 3. Figures 3 d and 3 e are the sequential TEM images extracted from the videos, showing the coalescence processes of the voids and Hg droplets, respectively. At 259 s, several voids were seen in Fig. 3 d (marked by the squares). After further e-beam irradiation for 10 s, a bridge began to appear between two neighboring voids with a distance of ~ 18 nm (marked by the rectangles). Such bridges became clearly visible during the following period of 30 s. Subsequently, the large voids were formed at 324 s as a result of the coalescence. The large voids would finally turn into a long crack-like feature (349 s). On the other hand, the coalescence was also realized through the nanobridges between two Hg droplets (Fig. 3 e). Initially (520 s), the two droplets (marked by the circles) were separated with a distance of ~ 8 nm. When they approached at 6 nm, a bridge (marked by the ellipse) appeared at this stage (555 s). The bridge got wider with the time (565 s), which induced the subsequent coalescence of the two droplets (585 s). As the time elapsed (605 s), the coalesced droplet continued changing its shape to further reduce the surface energy. Ink-jetting phenomenon of HgS NCs in liquid cell To study the Hg behavior at the solid-liquid interface, the structural evolution of HgS NCs in liquids was conducted. Figure 4 a shows the evolution of a single NC from a series of sequential TEM images (Supplementary Movie 4). The experiment was operated under a dose rate of ~ 5200 e/Å 2 ·s. Under the e-beam excitation (20 s), the voids were formed rapidly with the appearance of some small Hg nanodroplets (see details in Supplementary Fig. 2). The voids were eventually turned into the large ones (marked by the rectangle) through the coalescence process (e.g., 312 s and Supplementary Fig. 3). Different from the phenomena observed in the gas cell, the structural evolution of HgS in water underwent periodic jetting of Hg liquid, hereafter named as the ink-jetting event (such like the “ink-jetting” from cuttlefish). Upon irradiation for a relatively long time, the first ink-jetting began to appear at 338 s (marked by the circles). It spread quickly during the following seconds and then finished at 346 s. Within the next tens of seconds, the ink-jetting additionally occurred five times (the commence and end processes similar as that displayed above) and finally ended at 470 s. The beginning t s and finish time t f of each ink-jetting event are summarized in Fig. 4 b. From the inset, it can be seen that the period of spanning a whole ink-jetting process \(\text{∆}\text{t}\text{}\text{=}{\text{t}}_{\text{f}}\text{-}{\text{t}}_{\text{s}}\) was in the range of several to tens of seconds. Note that the time needed to initiate the ink-jetting event was decreased with the increase of the dose rate (Supplementary Fig. 4). Figure 4 c presents the dose rate-dependent jetting speed of the ink feature. The jetting rate of the ink increased from ~ 2.7 to 16.4 nm/s with the increment of dose rate from 3620 to 8780 e/Å 2 ·s. The Hg/S ratios under the different dose rates are shown in Fig. 4 d (the selected areas for EDS are given in the inset), revealing the distribution of Hg and S elements after the ink-jetting behavior. The variation of the Hg/S ratios was not significant under different dose rates, which was different from the overall trend observed in the gas environment (random distribution of large droplets displayed in Fig. 2 ). When multiple HgS NCs existed in the liquid cell, similar continuous ink-jetting phenomenon also occurred (Supplementary Fig. 5). During the e-beam irradiation, the voids preferentially arose and grew up, e.g., at the stages of 65 s and 107 s. The first ink-jetting began at 138 s, then spread and lasted for several seconds, and finally finished at 150 s. Afterwards, the second one was triggered at 169 s. The ink-like feature became larger in size at 170 and 172 s, and eventually stopped at 182 s. The last one (the seventh) was evolved in a similar way (began and finished at 282 s and 294 s, respectively). Ultimately, the HgS NC became relatively stable and showed no obvious morphological change. Note that other neighboring NCs also experienced the similar ink-jetting, forming an agglomerated particle at the end (the inset image at 294 s). Discussion Void nucleation, growth, and coalescence In the experiments we observed the evolution of voids that was categorized into the nucleation, growth, and coalescence processes. It has been documented that the voids would be formed through the thermal heating 28 , local stress concentrators caused by extended defects (e.g., dislocations and grain boundaries) 29 , Kirkendall effect 30 and atomic displacement induced vacancy zones 31 . The e-beam-induced temperature rise was normally in the range of several degrees 32,33 , indicating that heating did not dominate the formation of voids. The local stress concentrators and the Kirkendall effect might not mainly account for the void formation either, because no grain boundaries and/or diffusion couple with different rates were involved during the process. In the absence of material discontinuities, on the other hand, the direct transfer of e-beam energy to atoms during collision may be large enough to knock them out of their lattice sites, creating the vacancies so that the condensation of vacancy clusters induces the voids. On the basis of both energy and momentum conservation, the maximum kinetic energy E A transferred from an electron to an atom through collision is estimated using the following equation, $$\:{\text{E}}_{\text{A}}\text{}\text{=}\text{}\text{561}\text{ε}\text{}\left(\text{ε}\text{}\text{+}\text{}\text{2}\right)\text{}\text{/}\text{}\text{A}$$ 1 where \(\:\text{A}\) is the weight of atom and ε = E /( mc 2 ), E is the original energy of electron in TEM with 200 kV accelerating voltage, m is the mass of electron, and c is velocity of light. For the typical 200 keV e-beam in TEM, the E A values were calculated to be 2.62 and 16.37 eV for Hg and S, respectively. Upon comparison to the vacancy formation energies E v of 4.5 and 7.8 eV for Hg and S, it indicates that it was easier for S atoms to be knocked out than that for Hg atoms. Surprisingly, according to the EDS analysis the loss of Hg was more than that of S element (Supplementary Fig. 6), which was owing to the occurrence, movement, and evaporation of Hg droplets (Fig. 3 ). Such evolution of Hg droplets would further offer localized reduction in displacement energy for S, energetically favoring the vacancy clustering to facilitate the evolution of voids. In the next stage, the dynamical evolution includes the simultaneous growth and coalescence of existing voids as well as the formation of few new ones. Compared to the nucleation of new ones, the small voids tended to add into the existing voids and to merge to form the large ones, which was probably driven by the reduction of the total energy of the system. Interestingly, unlike the direct coalescence of voids, e.g., the behavior reported in the Bi nanoparticles induced by heating, the coalescence between two neighboring voids in the HgS NCs was achieved by the bridge with ~ 18 nm (Fig. 3 ). Ultimately, the large voids turned into a long crack-like feature to further lower the total energy. Such feature preferentially propagated along the direction of the crystal due to the fewer number of bonds bridging unit cells perpendicular to this direction. In this work, the structural evolution of the crystal tended to form the voids instead of the volume contraction so that the framework was maintained. This was probably due to the thermodynamic preference for reduction of the total surface energy of the voids greater than the crystal surface energy. Formation, movement and coalescence of Hg nanodroplets During the e-beam excitation of HgS semiconductor, a number of electron-hole (e–h) pairs are generated within an excitation volume. For a 200 kV e-beam with the typical current of 1.2 nA used here, the local rate of carrier pair generation was calculated to be approximately 3.10 × 10 5 pairs per second in the HgS NC (Supplementary Fig. 7, Supplementary Tables 1–2 and Supplementary Notes). The utilization of such generated electrons was then roughly estimated. As presented in Fig. 2 , about three discernible Hg nanodroplets with a diameter of ~ 2 nm (~ 7.26 × 10 3 atoms) formed at 2 s while ten bigger nanodroplets (diameter of ~ 10 nm) appeared at 400 s which contained about 3.02 × 10 6 Hg atoms. Within these e-beam excitation periods, the number of generated electrons were 6.20 × 10 5 and 1.24 × 10 8 for 2 s and 400 s, respectively. Despite the rough estimation, it provided a pictorial understanding for the formation of Hg nanodroplets (Hg 2+ + 2e \(\:\to\:\) Hg), namely, the formation of the 2 nm (~ 2.3%) and 10 nm (~ 4.9%) nanodroplets only consumed several percent of the reductive electrons, whereas most of the carriers were recombined in the material. After the formation, those Hg nanodroplets exhibited relatively large movement speed of ~ 56 nm/s at the dose rate of 4340 e/Å 2 ·s, in comparison to that of ~ 5–10 nm/s observed for the Bi nanodroplets 34 . Although the movement of metal nanodroplets has been rarely reported, several mechanisms about the driving forces originated from the gradient fields including temperature 21 , surface energy 35 , electric field 36 and light field 37 have been proposed for other common liquid droplets (e.g., water). Those factors might not be applicable or play the essential role for the phenomena observed in this work. It has also been shown that the ratchet surface leaded to the propulsion of the liquids, which was driven by the viscous force between the solid/liquid interface due to the Leidenfrost effect 38 . The HgS nanocrystals in our work adopted a saw-tooth morphological feature so that the Hg nanodroplets preferred to curve concavely near the tops of the ridges while presenting the convex characteristics elsewhere (Supplementary Fig. 8). In this scenario, we speculated that such ratchet surface may contribute to the fast movement of the Hg nanodroplets. During the e-beam-induced reduction of Hg, the nucleation of the nanodroplets occurred once the vapor pressure of Hg exceeded the saturated one. Such variation in the surface curvature would generate a pressure differential Δ p between the concave ridge and the neighboring convex position, forming a net force to drive the motion of the nanodroplet (Supplementary Fig. 8). Such a pictorial understanding was again verified by the fact that the glide velocity of the Hg nanodroplets increased dramatically at the high e-beam dose rates since more Hg vapor was formed upon the irradiation (Fig. 3 ). During the movement, the Hg nanodroplets would coalesce with a relatively large distance of ~ 5 nm through the bridges (Fig. 3 ), which was different from that observed in other systems. For example, the Bi nanodroplets underwent a sudden coalescence on the SrBi 2 Ta 2 O 9 platelet 39 , while the fusion or coalescence of Au nanocrystals was realized by the nanochannel with a critical spacing of less than 1 nm 40–42 . Moreover, the coalescence of nanobubbles in liquids was observed to occur within a distance of ~ 2 nm between two bubbles 43 . In this work, the e-beam irradiation induced the reduction of Hg 2+ to Hg on the HgS NCs. As the time elapsed, the accumulation of Hg atoms might create the atomic chains accordingly, resulting in the formation of relatively long bridges that finally leaded to the coalescence between the nanodroplets. Mechanism for continuous ink-jetting behavior It is known that the irradiation of water by the electron beam generally generates a variety of radiolysis products, including the common oxidative •OH, H 2 O 2 and reductive solvated electron e h − species 44 . The steady-state concentrations of the radiolysis species were calculated and summarized (Supplementary Tables 3, 4, 5), presenting that the concentration of the oxidative species was higher than that of the reductive ones. Meanwhile, the oxidative species possess very high reduction potentials (Supplementary Table 6), which have been reported to play the vital role for etching the nanostructures (especially metals) in liquids 31,45–48 . Despite the inevitable existence of slight etching, the HgS semiconductor studied here demonstrated the distinct behavior from that was shown in the metal nanostructures (almost pure etching). Different types of scavengers were designed to suppress a certain number of specific species so that the dominated ones for the ink-jetting phenomenon would be clarified. Figure 5 a shows the sequential TEM images in the electrospun liquid cells with the addition of H 2 O 2 (scavenger for reductive species). In this case, the e-beam-induced oxidative species would predominate. The HgS NCs were gradually etched and more cavity feature was formed with the increment of time. No ink-jetting phenomenon was observed even during the long irradiation for ~ 300 s. The above behavior was further validated in the thin carbon liquid cells with the same addition of H 2 O 2 (Fig. 5 b). Obvious contrast from the bubbles was observed, manifesting the liquid environment inside the carbon liquid cell (Supplementary Fig. 9). Similar etching phenomenon was also observed as the time elapsed to several hundreds of seconds. Additional ex-situ experiments were designed to distinguish the etching effect from either H 2 O 2 or •OH (see Methods for details). Figure 5 c depicts the TEM images of the HgS NCs treated mainly by •OH. The morphological change was seen at 10 min and it became obvious after 30 min. Most parts of the NCs were etched off after 180 min, resulting in the complete collapse of the initial bipyramid structure. In contrast, the HgS NCs with the addition of pure Co 2+ or H 2 O 2 presented no obvious morphological change at the same time scale (Supplementary Fig. 10). Upon comparison of the above results, it indicates that the •OH plays the dominant role in etching the HgS NCs. Figure 5 d shows the time-dependent TEM images of the ink-jetting phenomenon in the electrospun liquid cells with the addition of methanol (scavenger for oxidative species, Supplementary Movie 5). Similar to the structural evolution of HgS NCs in water, the voids arose rapidly and the ink-jetting phenomenon occurred consecutively. Distinctly, the first ink-jetting occurred at ~ 66 s, which was significantly shorter than that in the water condition (~ 314 s). Meanwhile, the interval time \(\text{∆}\text{t}{\prime}\text{}\text{=}{\text{}\text{t}}_{\text{n}}\text{-}\text{}{\text{t}}_{\text{n-1}}\) between each ink-jetting event also became shorter, e.g., the fifth jetting behavior was finished within only ~ 4 s. Given the nature of oxidative scavenger in the case of methanol, it suggests that the reductive electrons might play the key role for the continuous ink-jetting phenomenon. This was further evidenced by the fact that the Hg nanodroplets immediately nucleated under the reductive environment after the e-beam excitation for 2 s in the gas cells with the absence of •OH (Fig. 2 ). For the case of the liquid cells, the longer time needed to trigger the ink-jetting (Fig. 4 , 338s) indicates that part of the reductive electrons was consumed by the oxidative species and the long-time accumulation of the sufficient electrons therefore allowed the subsequent ink-jetting. Based on the above discussion, a competition exists for the reduction of Hg 2+ to the formation of Hg droplets, i.e., the reductive electrons promote such behavior whereas the oxidative species inhibit it. Once the accumulated electrons reach the threshold value during such competition process, the ink-jetting behavior occurs. Since the reductive electrons are consumed in each reduction-involved ink-jetting process, a certain amount of time would be thereby required to accumulate enough electrons for the next jetting behavior. Figure 5 e shows the relationship between the e-beam irradiation time and the ink-jetting frequency under different liquid conditions. At each frequency, the irradiation time needed to trigger the ink-jetting under the addition of methanol was shorter than that in the water. The interval time between two sequential ink-jetting processes is quantitatively displayed in Fig. 5 f. Compared to the interval time of ~ 11–22 s in water, the time span under the addition of methanol was significantly shortened (~ 3–6 s). The phenomenon was ascribed to the consumption of a certain number of oxidative species through the addition of methanol. In this scenario, more electrons had the chance of being involved in the reduction process, leading to the shortened time for triggering the ink-jetting behavior. Schematic diagram of nanodroplet dynamics in gas and liquid cells The overall evolution pictures of Hg Nanodroplets in the gas and liquid cells are schematically summarized in Fig. 6 . In the gas cells (Fig. 6 a), the direct transfer of e-beam energy to the Hg and S atoms knocks them out of the lattice sites, creating a large number of the vacancies. The condensation of the vacancy clusters induces the voids, which is also accompanied by the appearance of Hg nanodroplets due to the reduction of Hg 2+ to Hg. Subsequently, the voids gradually grow up after coalescence through the bridges, which further turn into the crack-like structure preferentially along the long-axis direction. Meanwhile, the Hg nanodroplets move rapidly, and come into coalescence through the bridges when they are close each other, forming the bigger ones accordingly. With the continuous coalescence process, the large droplets are finally formed and stay relatively stable on the substrate. In the case of liquid cells (Fig. 6 b), the voids also arise rapidly in the preliminary stage upon the e-beam excitation, which are evolved into the large ones as the time elapses. Compared to that in the gas cells, distinctly, some smaller Hg nanodroplets appear in the early stage, but without the apparent growth. After the long-time excitation so that the accumulated electrons achieve the threshold, the ink-jetting behavior begins to occur. Such ink-like feature spread, and then becomes less obvious at the later stage. After a certain time of additional e-beam excitation, the second ink-jetting appears once the reaccumulation of the reductive electrons becomes sufficient for triggering such behavior. In this regard, the continuous the ink-jetting behaviors become feasible, with the interval time of two neighboring ones depending on the competition between the reductive electrons (accumulation) and the oxidative species (consumption of electrons). Ultimately, a stable liquid Hg layer is formed after the several ink-jetting processes at a certain dose rate. In summary, the distinct evolution dynamics of the Hg nanodroplets mediated at the solid-gas and solid-liquid interfaces were directly visualized and statistically investigated by in-situ TEM. Upon exposure to e-beam in the gas cells, the voids and Hg nanodroplets nucleated and grew up, which were then coalesced into the large ones through the nanobridges. The voids could be further evolved into the crack-like structure preferentially along the direction of the HgS solid substrate. The Hg droplets moved fast at the solid-gas interface and finally became relatively stable at each dose rate, which was distinct from the evaporation behavior observed at the solid-vacuum interface. In contrast to the typical behavior of the voids and Hg nanodroplets observed at either solid-gas or solid-vacuum interface, statistical results revealed the occurrence of the ink-jetting phenomenon in the liquid cells. Two competitive factors governed the interval time between the neighboring ink-jetting events, namely, the reductive electron species facilitated the shortening of such period while the oxidative species like •OH acted in the opposite manner. These phenomena were further verified by the ex-situ experiments with the addition of additional H 2 O 2 or methanol. Our results contribute to advance a fundamental understanding of the full and unique evolution picture of liquid metal nanodroplets at nanoscale solid-gas and solid-liquid interfaces, and provide the experimental approach of potentially modulating droplets behavior with controllable functionality through interface engineering. Methods Synthesis of HgS seeds. The HgS seed nanoparticles (NPs) were synthesized based on a wet-chemical method. Specifically, 128 mg of Hg(NO 3 ) 2 ·H 2 O was added into 20.0 mL of deionized water in a round-bottom flask, followed by the dropwise addition of 4 mL of D-form penicillamine aqueous solution (0.09 M) under stirring to obtain a colorless solution. Then, 0.6 mL of NaOH aqueous solution (2 M) was added into the above colorless solution. After further stirring for 2 min, 2.0 mL of thioacetamide solution (0.18 M) was added into the mixture solution. The flask was sealed and placed in a 38 o C water bath for 15 h under stirring. After the reaction, the seed NPs were collected by centrifugation at 6000 rpm for 10 min, washed three times with isopropanol, and re-dispersed in 5.0 mL of deionized water for further use. Epitaxial growth of HgS NCs. Chiral α-HgS NCs were prepared by the seed-mediated epitaxial growth method using the above as-synthesized seeds. Before the epitaxy, a Hg precursor solution was prepared by the dissolution of 74.4 mg Hg(NO 3 ) 2 ·H 2 O into 7.2 mL of deionized water followed by the addition of 1.8 mL of D-penicillamine aqueous solution (0.09 M), whereas a S precursor solution was obtained by dissolving 19.8 mg of thioacetamide in 10 mL of deionized water. For a typical epitaxial growth, 50 µL of HgS seeds colloidal solution was dispersed into 5 mL of deionized water in a three-neck round-bottom flask submerged in the 38 o C water bath. 1.0 mL of D-penicillamine aqueous solution (0.09 M) and 0.6 mL of NaOH aqueous solution (2 M) were dropwise added into the flask under stirring. Subsequently, the as-prepared Hg and S precursor solutions were slowly injected into the flask by a syringe pump with an injection rate of 1.0 mL/h for 4 h. After the reaction, the orange precipitates were obtained by centrifugation at 6000 rpm for 10 min, washed three times with isopropanol and finally dispersed in x mL of deionized water for later studies. Chirality and surface profile characterization. The chirality of HgS samples was characterized by CD spectroscopy. The CD spectra were obtained on a JASCO J-1500 spectropolarimeter with an optical length of 10 mm at 293.15 K. Atomic force microscopy (AFM) was used to reveal the surface profiles of the HgS NCs (FastScan Bio, Bruker, USA). Ex-situ observation of etching behavior. To investigate the effect from the oxidative species, the Fenton reaction was performed to produce the •OH radicals. Briefly, 30 mg of CoCl 2 power was ultrasonically dispersed into 10 mL of HgS suspension (0.1 mg/mL). The Fenton reaction was triggered by the addition of 0.5 mL of H 2 O 2 into the above solution at room temperature under dark environment with stirring. The Fenton reaction formula is shown as follows, Co 2+ + H 2 O 2 → Co 3+ + OH − + •OH ( 2 ) 0.5 mL of suspension was collected at each given reaction time and added into a test tube containing 1 mL of methanol which was used to terminate the Fenton reaction. Finally, a drop of the above suspension was directly dropped onto the carbon film-coated grid for TEM imaging. We also prepared the samples with the addition of only either H 2 O 2 or CoCl 2 to distinguish the effect from the above •OH radicals. 5 mL of H 2 O 2 or 30 mg of CoCl 2 power was added into 10 mL of HgS suspension (0.1 mg/mL) at room temperature, which was placed under dark environment with stirring. The other procedures were the same to that presented in the above one. The as-prepared samples were finally used to the later TEM characterization. Liquid and gas cell fabrication. The liquid cells were prepared by a coaxial electrospinning technique reported in our previous study. Frist, two kinds of liquid precursors (shell and core liquid precursors) were prepared, i.e., the shell liquid precursor was obtained by dissolving 3 g of polyvinyl acetate (PVAC) in 20 mL of dimethyl carbonate (DMC) under stirring for 8 h, while the core liquid precursor was prepared by dispersion of 1 mg of the as-prepared chiral α-HgS NCs into 10 mL of deionized water. Note that 0.05 g of glycerol was also added into the core liquid precursor to reduce the water volatilization during electrospinning. Then, the core and shell liquid precursors were pumped into two syringes for electrospinning with the flow rates of the core and shell liquids set at 2.0 µm/s and 7.8 µm/s, respectively. The applied voltage and roller speed were set as 15 kV and 60 r/min, respectively. Finally, the copper grids with ~ 20 nm thick carbon films were directly used to collect the fibers for the ready-to-use liquid cell TEM (collection time was 45 s). For the gas cell fabrication, the procedures were almost the same but without the addition of glycerol so that the core water evaporated during electrospinning. To investigate the effect of the scavengers on the reductive and oxidative species, the liquid cells with the additional addition of either H 2 O 2 or methanol were also fabricated by electrospinning. All the electrospinning steps were the same as that shown above, except the preparation of the core liquid precursors. For this preparation, the extra addition of either 0.5 mL of H 2 O 2 or 0.5 mL of methanol into 10 mL of HgS suspension (0.1 mg/mL) was acted as the core precursor. In addition, the carbon-film liquid cells were further prepared to verify the phenomena observed in the electrospun ones. Briefly, 0.5 mL of H 2 O 2 was firstly added into 10 mL of HgS suspension (0.1 mg/mL). Then, 1.5 µL of the above suspension was dropped onto one piece of the carbon film-coated grid and subsequently sandwiched by another one face to face. The liquid cells were dried naturally under ambient atmosphere for about 2 h. After the evaporation of excessive liquid solution, the liquid pockets containing the HgS NCs were finally formed between two thin carbon films owing to van der Waals force. In-situ TEM visualization of structural dynamics. Upon the e-beam irradiation, the structural evolution of HgS NCs in the liquid and gas cells under different conditions was in-situ visualized in an FEI Talos F200X TEM operating at 200 kV. The dynamical processes of the e-beam-induced evolution were then recorded by a digital camera. The electron dose rate was tuned in a range of 500-10000 e/Å 2 s to ensure the initiation of the structural evolution. To reveal the compositional change during the evolution, the high-angle annular dark-field (HAADF) and EDS techniques in the scanning transmission electron microscopy (STEM) mode were utilized to analyze the elemental composition and distribution under different dynamical stages. Declarations Competing interests The authors declare no competing interests. Author contributions B. C. and L. X. conceived the research. L. X. synthesized the materials and performed the TEM experiments. Z. C., Z. L., C. Z., S. P., and Y. L. assisted in the synthesis of HgS and preparation of gas/liquid cells. L. X. and B. C. wrote the manuscript. All authors contributed to the data analysis and discussion. Acknowledgements This work is supported by the National Natural Science Foundation of China (No. 92061116). The authors also acknowledge the financial support from the Science and Technology Commission of Shanghai Municipality (22ZR1428400) and the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning. References Xie C, Niu Z, Kim D, Li M, Yang P (2020) Surface and interface control in nanoparticle catalysis. Chem Rev 120:1184–1249 Stamenkovic VR, Strmcnik D, Lopes PP, Markovic NM (2017) Energy and fuels from electrochemical interfaces. Nat Mater 16:57–69 Jun Y-S, Kim D, Neil CW (2016) Heterogeneous nucleation and growth of nanoparticles at environmental interfaces. Acc Chem Res 49:1681–1690 Xiao Y et al (2020) Understanding interface stability in solid-state batteries. Nat Rev Mater 5:105–126 Luo D, Li X, Dumont A, Yu H, Lu Z-H (2021) Recent progress on perovskite surfaces and interfaces in optoelectronic devices. Adv Mater 33:2006004 Wang Y, Cai R, Chen C (2019) The nano-bio interactions of nanomedicines: understanding the biochemical driving forces and redox reactions. Acc Chem Res 52:1507–1518 Peng X et al (2022) Identification of a quasi-liquid phase at solid–liquid interface. Nat Commun 13:3601 Lee SW, Kim H, Park JY (2023) How hot electron generation at the solid-liquid interface is different from the solid-gas interface. Nano Lett 23:5373–5380 Liu F et al (2019) Catalytic 1–propanol oxidation on size-controlled platinum nanoparticles at solid-gas and solid-liquid interfaces: significant differences in kinetics and mechanisms. J Phys Chem C 123:7577–7583 Luo L et al (2018) Atomic origins of water-vapour-promoted alloy oxidation. Nat. Mater. 17, 514 – 518 Wang W et al (2022) Solid-liquid-gas reaction accelerated by gas molecule tunnelling-like effect. Nat Mater 21:859–863 Swisher JH, Jibril L, Petrosko SH, Mirkin CA (2022) Nanoreactors for particle synthesis. Nat Rev Mater 7:428–448 Kaminski TS, Garstecki P (2017) Controlled droplet microfluidic systems for multistep chemical and biological assays. Chem Soc Rev 46:6210–6226 Wan J et al (2023) Visualizing facets asymmetry induced directional movement of cadmium chloride nanomotor. Nano Lett. 23, 10132 – 10139 Sicard F, Toro-Mendoza J (2021) Armored droplets as soft nanocarriers for encapsulation and release under flow conditions. ACS Nano 15:11406–11416 Qu M et al (2022) Controlling process instability for defect lean metal additive manufacturing. Nat Commun 13:1079 Liu Y et al (2017) Capillary-force-induced cold welding in silver-nanowire-based flexible transparent electrodes. Nano Lett 17:1090–1096 Chu K-H, Xiao R, Wang EN (2010) Uni-directional liquid spreading on asymmetric nanostructured surfaces. Nat Mater 9:413–417 Jadidi M, Moghtadernejad S, Dolatabadi A (2015) A comprehensive review on fluid dynamics and transport of suspension/liquid droplets and particles in high-velocity oxygen-fuel (HVOF) thermal spray. Coatings 5, 576 – 645 Liu Y et al (2023) Recent advances in inkjet-printing technologies for flexible/wearable electronics. Nanoscale 15:6025–6051 Brzoska JB, Brochard-Wyart F, Rondelez F (1993) Motions of droplets on hydrophobic model surfaces induced by thermal gradients. Langmuir 9:2220–2224 Zhu C et al (2023) High electric fields on water microdroplets catalyze spontaneous and fast reactions in halogen-bond complexes. J Am Chem Soc 145:21207–21212 Koren E et al (2011) Obtaining uniform dopant distributions in VLS-grown Si nanowires. Nano Lett 11:183–187 Maliakkal CB, Tornberg M, Jacobsson D, Lehmann S, Dick KA (2021) Vapor–solid–solid growth dynamics in GaAs nanowires. Nanoscale Adv 3:5928–5940 Chaudhury MK, Whitesides GM (1992) How to make water run uphill. Science 256:1539–1541 Liu Z et al (2021) Versatile printing of substantial liquid cells for efficiently imaging in situ liquid-phase dynamics. Nano Lett. 21, 6882 – 6890 Cao Z, He J, Liu Z, Zhang H, Chen B (2021) Chirality affecting reaction dynamics of HgS nanostructures simultaneously visualized in real and reciprocal space. ACS Nano 15:16255–16265 Li Y et al (2017) In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles. Nat Commun 8:14462 Gerstein G et al (2017) Formation and growth of voids in dual-phase steel at microscale and nanoscale levels. J Mater Sci 52:4234–4243 Chee SW, Tan SF, Baraissov Z, Bosman M, Mirsaidov U (2017) Direct observation of the nanoscale Kirkendall effect during galvanic replacement reactions. Nat Commun 8:1224 Huang X, Jones T, Fan H, Willinger M-G (2016) Atomic-scale observation of irradiation-induced surface oxidation by in situ transmission electron microscopy. Adv Mater Interfaces 3:1600751 Grogan JM, Schneider NM, Ross FM, Bau HH (2014) Bubble and pattern formation in liquid induced by an electron beam. Nano Lett 14:359–364 Hauwiller MR et al (2019) Gold nanocrystal etching as a means of probing the dynamic chemical environment in graphene liquid cell electron microscopy. J Am Chem Soc 141:4428–4437 Li J, Wang Z, Deepak FL (2017) In situ atomic-scale observation of droplet coalescence driven nucleation and growth at liquid/solid interfaces. ACS Nano 11:5590–5597 Zhang Z et al (2019) Unidirectional self-driving liquid droplet transport on a monolayer graphene-covered textured substrate. ACS Appl Mater Interfaces 11:28562–28570 Pollack MG, Fair RB, Shenderov AD (2000) Electrowetting-based actuation of liquid droplets for microfluidic applications. Appl Phys Lett 77:1725–1726 Ichimura K, Oh S-K, Nakagawa M (2000) Light-driven motion of liquids on a photoresponsive surface. Science 288:1624–1626 Linke H et al (2006) Self-propelled leidenfrost droplets. Phys Rev Lett 96:154502 Li Y et al (2016) Atomic scale imaging of nucleation and growth trajectories of an interfacial bismuth nanodroplet. ACS Nano 10:2386–2391 Anand U, Lu J, Loh D, Aabdin Z, Mirsaidov U (2016) Hydration layer-mediated pairwise interaction of nanoparticles. Nano Lett 16:786–790 Yue S, Yuan W, Deng Z, Xi W, Shen Y (2022) In situ TEM observation of the atomic transport process during the coalescence of Au nanoparticles. Nano Lett 22:8115–8121 Jin B, Sushko ML, Liu Z, Jin C, Tang R (2018) In situ liquid cell TEM reveals bridge-induced contact and fusion of Au nanocrystals in aqueous solution. Nano Lett 18:6551–6556 Zhang Z et al (2021) Visualization of bubble nucleation and growth confined in 2D flakes. Small 17:2103301 Schneider NM et al (2014) Electron-water interactions and implications for liquid cell electron microscopy. J Phys Chem C 118:22373–22382 Ye X et al (2016) Single-particle mapping of nonequilibrium nanocrystal transformations. Science 354, 874 – 877 Yan C et al (2022) Facet-selective etching trajectories of individual semiconductor nanocrystals. Sci Adv 8:1700 Ye M et al (2023) Revealing dominant oxidative species in reactive oxygen species-driven rapid chemical etching. Nano Lett 23:7319–7326 Peng X et al (2024) Unveiling corrosion pathways of Sn nanocrystals through high-resolution liquid cell electron microscopy. Nano Lett 24:1168–1175 Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryInformation.docx SupplementaryMovie1.mp4 In-situ TEM observation of the nucleation and growth dynamics of voids and Hg nanodroplets in the gas cell under a dose rate of ~3240 e/Å2·s from 0 to 1150 s and a dose rate of ~7350 e/Å2·s from 1150 SupplementaryMovie2.mp4 In-situ video of the coalescence process of the voids in the gas cell under a dose rate of ~1790 e/Å2·s. Movie at nine-fold acceleration (9 ) SupplementaryMovie3.mp4 In-situ TEM observation of the coalescence behavior of the Hg nanodroplets in the gas cell under a dose rate of ~2830 e/Å2·s. Movie at nine-fold acceleration (9 ) SupplementaryMovie4.mp4 In-situ TEM observation of the ink-jetting events in the liquid cell under a dose rate of ~5200 e/Å2·s. Movie at nine-fold acceleration (9 ) SupplementaryMovie5.mp4 In-situ video of the ink-jetting behavior in the liquid cell with the effect from additional methanol. Movie at two-fold acceleration (2 ) Cite Share Download PDF Status: Published Journal Publication published 17 Apr, 2025 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4865225","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":337592053,"identity":"6ce3c803-a5d8-4ad0-9c9d-ddbaf4986628","order_by":0,"name":"Bin Chen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAtklEQVRIiWNgGAWjYDACCRBRwcAM5vAQr+UMAzMPaVoY26CqidLCP7v54YeP8+rY7SUSGB+8bWOQNydoyZ1jxpIztx1m5pFIYDac28ZguLOBgBYDiRw2Zt5tB0Ba2KR52xgSDA4Qo+XvnDqQFvbfxGthbGAG28JMlBawX3qOAf1y5mGz5JxzEoYbCGkBh9iPmrpk9vbkgx/elNnIE7QFBpKBsdPAAI1Z4oAd8UpHwSgYBaNgxAEAqUM2Wq8GTHwAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-6832-906X","institution":"Shanghai Jiao Tong University","correspondingAuthor":true,"prefix":"","firstName":"Bin","middleName":"","lastName":"Chen","suffix":""},{"id":337592054,"identity":"400693e5-e821-41ff-a88e-5b20f90527dd","order_by":1,"name":"Linfeng Xu","email":"","orcid":"","institution":"Shanghai Jiao Tong University","correspondingAuthor":false,"prefix":"","firstName":"Linfeng","middleName":"","lastName":"Xu","suffix":""},{"id":337592055,"identity":"2ddfab9d-43cb-49a0-b4ff-21ae5613fa1b","order_by":2,"name":"Zetan Cao","email":"","orcid":"","institution":"Shanghai Jiao Tong University","correspondingAuthor":false,"prefix":"","firstName":"Zetan","middleName":"","lastName":"Cao","suffix":""},{"id":337592056,"identity":"ba5b406f-6b8b-4089-aec6-23a0a80d62ba","order_by":3,"name":"Zhiwen Liu","email":"","orcid":"","institution":"Shanghai Jiao Tong University","correspondingAuthor":false,"prefix":"","firstName":"Zhiwen","middleName":"","lastName":"Liu","suffix":""},{"id":337592057,"identity":"69328303-ce3d-4c9a-930d-5f225f0b014d","order_by":4,"name":"Cheng Zheng","email":"","orcid":"","institution":"Shanghai Jiao Tong University","correspondingAuthor":false,"prefix":"","firstName":"Cheng","middleName":"","lastName":"Zheng","suffix":""},{"id":337592058,"identity":"e527e706-32ce-4464-8083-6eb5e6bbe1a7","order_by":5,"name":"Simin Peng","email":"","orcid":"","institution":"Shanghai Jiao Tong University","correspondingAuthor":false,"prefix":"","firstName":"Simin","middleName":"","lastName":"Peng","suffix":""},{"id":337592059,"identity":"87befec7-75f9-4cbe-bcdf-1f9b7010af2c","order_by":6,"name":"Yong Lu","email":"","orcid":"","institution":"Shanghai Jiao Tong University","correspondingAuthor":false,"prefix":"","firstName":"Yong","middleName":"","lastName":"Lu","suffix":""}],"badges":[],"createdAt":"2024-08-06 03:40:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4865225/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4865225/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41467-025-59063-z","type":"published","date":"2025-04-17T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":62070613,"identity":"7acd00a3-acf9-40cb-8c2f-88c39150c44b","added_by":"auto","created_at":"2024-08-09 02:31:49","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":689347,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStructural characterization of HgS for in-situ gas/liquid cell TEM. a \u003c/strong\u003eSchematic illustration of the atomic structure of α-HgS.\u003cstrong\u003e b \u003c/strong\u003eTypical TEM image of the as-synthesized HgS (left) and high-resolution image with the d-value of 3.359 Å corresponding to the (101) plane of α-HgS (right). The inset shows the corresponding diffraction pattern. \u003cstrong\u003ec\u003c/strong\u003eCircular dichroism spectra of the chiral and achiral HgS. \u003cstrong\u003ed\u003c/strong\u003e Schematic of the time-resolved imaging of evolution dynamics in the gas/liquid cell. \u003cstrong\u003ee \u003c/strong\u003eStructure of the gas/liquid cell (top) and the typical TEM image of the electrospun cell containing the HgS NC (bottom). \u003cstrong\u003ef\u003c/strong\u003e TEM images and EDS spectra of the HgS NCs after the e-beam irradiation, showing the identification of the dark nanodroplets (top) and the white feature (bottom), respectively.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/b520788d0a4566eb92d6a8d3.png"},{"id":62070603,"identity":"82bda041-c098-4514-b7ed-9a1c3743e0f0","added_by":"auto","created_at":"2024-08-09 02:31:48","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":642703,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStructural evolution of the voids and Hg nanodroplets in the gas cell. a\u003c/strong\u003e A series of time-dependent TEM images revealing the formation of voids and Hg nanodroplets as well as the coalescence of the voids. \u003cstrong\u003eb\u003c/strong\u003e The voids turned into the crack-like feature, and such crack was lengthened, coalesced and finally evolved into the long one at 380 s. \u003cstrong\u003ec \u003c/strong\u003eHg nanodroplets gradually grew into a size of approximately 10-15 nm from 410 to 720 s under a dose rate of 3240 e/Å\u003csup\u003e2\u003c/sup\u003e·s. As the dose rate was increased to 7350 e/Å\u003csup\u003e2\u003c/sup\u003e·s, the Hg nanodroplets was further enlarged through coalescence (1150 s) and finally became relatively stable with the size of ~70 nm at (1250 s).\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/a6f95d2a9832a3676472b636.png"},{"id":62070604,"identity":"2ae455e7-dce1-446f-8a46-ff029f3d4711","added_by":"auto","created_at":"2024-08-09 02:31:48","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":518058,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAnalyses of the behaviors from the voids and Hg nanodroplets. a\u003c/strong\u003e The relationship between the size of Hg nanodroplets and the dose rate. The inset shows the growth speed of Hg nanodroplets as a function of the dose rate. \u003cstrong\u003eb\u003c/strong\u003e The variation of the Hg/S ratio under different dose rates at five selected areas illustrated in the inset. \u003cstrong\u003ec\u003c/strong\u003e The movement speed of the voids and nanodroplets as a function of the dose rate. The inset presents the movement velocities at the dose rates lower than 4000 e/Å\u003csup\u003e2\u003c/sup\u003e·s . \u003cstrong\u003ed \u003c/strong\u003eTime-dependent TEM images showing the coalescence process of the voids through the bridges. The crack-like feature was formed after the coalescence. \u003cstrong\u003ee \u003c/strong\u003eThe detailed coalescence process between two Hg droplets through the nanobridges. The inset at the 520 s image displays the location of such an example where the coalescence occurred (marked by the dotted circle).\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/c11050c65f87d6dc54ddbe6d.png"},{"id":62070605,"identity":"87567123-f2d2-43fc-a445-8709cd51d13f","added_by":"auto","created_at":"2024-08-09 02:31:49","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":721088,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eJetting behavior of liquid Hg in the liquid cell. a \u003c/strong\u003eTime-dependent TEM images showing the ink-jetting phenomenon upon e-beam excitation of the HgS NC. Six times of ink-jetting was observed, revealing the cycling of the beginning-spread-finish processes. \u0026nbsp;\u003cstrong\u003eb\u003c/strong\u003e The beginning and finish times for each ink-jetting event. The inset shows the total time of each ink-jetting process.\u003cstrong\u003ec \u003c/strong\u003eThe jetting speed of the liquid Hg as a function of the dose rate. \u003cstrong\u003ed\u003c/strong\u003e The relationship between the Hg/S ratio in different areas and the dose rate. The variation of the Hg/S ratio was not obvious, compared to that in the gas cell.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/7a02e9296d8b880f0f5b4d7a.png"},{"id":62070612,"identity":"4edd2b25-44e5-464f-9917-2687e565e981","added_by":"auto","created_at":"2024-08-09 02:31:49","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1064165,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLiquid environments with addition of reductive/oxidative scavengers. a \u003c/strong\u003eSequential TEM images of the etching phenomenon in the electrospun liquid cell with the addition of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e. \u003cstrong\u003eb \u003c/strong\u003eControl experiment in the carbon liquid cell with the addition of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e.\u003cstrong\u003e c \u003c/strong\u003eTEM images of the HgS NCs treated by the Fenton reaction for different periods. \u003cstrong\u003ed \u003c/strong\u003eTime-dependent TEM images of the ink-jetting behavior in the electrospun liquid cell with the addition of methanol. \u003cstrong\u003ee \u003c/strong\u003eThe e-beam irradiation time and \u003cstrong\u003ef\u003c/strong\u003e the interval time between two neighboring ink-jetting processes as a function of the jetting frequency in water and that with addition of methanol.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/0bc2927a9b707fc347e0b281.png"},{"id":62071059,"identity":"cae73887-1dcf-4301-afb0-52391c17ba3a","added_by":"auto","created_at":"2024-08-09 02:39:49","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":231153,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematics of overall evolutions of Hg Nanodroplets in the gas and liquid cells. a \u003c/strong\u003eDynamics of the voids and Hg nanodroplets in the gas cell. Upon the e-beam excitation, the voids and Hg nanodroplets are formed, which are coalesced into the large ones through the nanobridges. The large voids are evolved into the crack-like feature along the long-axis direction of the HgS nanobipyramid.\u003cstrong\u003e b\u003c/strong\u003eInk-jetting behavior in the liquid cell. The voids are formed rapidly with the occurrence of small Hg nanodroplets. Such voids are evolved into the big ones at the later stage. As the accumulated electrons reach the threshold, the ink-jetting suddenly happens. The ink-like feature spreads, which will be ended after a certain time. The ink-jetting occurs several times with the interval time depending on the competition between the reductive electrons and the oxidative species in the liquid cell.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/02e95a3998015d75c2ca0ce9.png"},{"id":80878116,"identity":"ae2cc955-9f79-438b-acba-23029e6bff6d","added_by":"auto","created_at":"2025-04-18 07:08:13","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5740147,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/2e92a701-feac-4a05-96cb-509bcca8de59.pdf"},{"id":62071060,"identity":"ff05592c-5d45-4d34-8758-ce9ba8c58bf8","added_by":"auto","created_at":"2024-08-09 02:39:49","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":9463423,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/3bc4c38b99267fa19f304f4b.docx"},{"id":62070607,"identity":"a9a9e27c-7adb-4b50-b10c-0a8d527564e4","added_by":"auto","created_at":"2024-08-09 02:31:49","extension":"mp4","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":4487258,"visible":true,"origin":"","legend":"In-situ TEM observation of the nucleation and growth dynamics of voids and Hg nanodroplets in the gas cell under a dose rate of ~3240 e/\u0026#x00C5;2\u0026#x00B7;s from 0 to 1150 s and a dose rate of ~7350 e/\u0026#x00C5;2\u0026#x00B7;s from 1150","description":"","filename":"SupplementaryMovie1.mp4","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/303f1fe640f3616116aa8dda.mp4"},{"id":62070606,"identity":"8c285273-b024-46da-a9fd-597a529a2a9a","added_by":"auto","created_at":"2024-08-09 02:31:49","extension":"mp4","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":5109459,"visible":true,"origin":"","legend":"\u003cp\u003eIn-situ video of the coalescence process of the voids in the gas cell under a dose rate of ~1790 e/Å2·s. Movie at nine-fold acceleration (9 )\u003c/p\u003e","description":"","filename":"SupplementaryMovie2.mp4","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/7892e37e65c057eaec182132.mp4"},{"id":62070611,"identity":"306ab522-1a24-43d5-8442-75980db9ac3a","added_by":"auto","created_at":"2024-08-09 02:31:49","extension":"mp4","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":5420462,"visible":true,"origin":"","legend":"\u003cp\u003eIn-situ TEM observation of the coalescence behavior of the Hg nanodroplets in the gas cell under a dose rate of ~2830 e/Å2·s. Movie at nine-fold acceleration (9 )\u003c/p\u003e","description":"","filename":"SupplementaryMovie3.mp4","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/de0b3bef3228e2fb163d769e.mp4"},{"id":62070608,"identity":"4a66e789-2bde-4508-85d3-aa138e1e54c3","added_by":"auto","created_at":"2024-08-09 02:31:49","extension":"mp4","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":4895072,"visible":true,"origin":"","legend":"\u003cp\u003eIn-situ TEM observation of the ink-jetting events in the liquid cell under a dose rate of ~5200 e/Å2·s. Movie at nine-fold acceleration (9 )\u003c/p\u003e","description":"","filename":"SupplementaryMovie4.mp4","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/49912d0abb260309c6bfcee2.mp4"},{"id":62070614,"identity":"7233c7a5-93ff-466f-8f2c-66b760aafbe2","added_by":"auto","created_at":"2024-08-09 02:31:49","extension":"mp4","order_by":6,"title":"","display":"","copyAsset":false,"role":"supplement","size":4564946,"visible":true,"origin":"","legend":"\u003cp\u003eIn-situ video of the ink-jetting behavior in the liquid cell with the effect from additional methanol. Movie at two-fold acceleration (2 )\u003c/p\u003e","description":"","filename":"SupplementaryMovie5.mp4","url":"https://assets-eu.researchsquare.com/files/rs-4865225/v1/b1f28f5bda4a1746a520c393.mp4"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Filming nanodroplet running and jetting mediated by nanoscale solid-gas and solid-liquid interface","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAn interface refers to the contact boundary plane, separating two phases that are chemically and/or structurally distinct, each of which may be solid, liquid or gaseous. The ubiquitous interfaces play a vital role in determining the properties and processing of almost all materials, which have promoted great interest in areas including catalysis\u003csup\u003e1\u003c/sup\u003e, electrochemistry\u003csup\u003e2\u003c/sup\u003e, nucleation and growth\u003csup\u003e3\u003c/sup\u003e, batteries\u003csup\u003e4\u003c/sup\u003e, optoelectronics\u003csup\u003e5\u003c/sup\u003e, and biological reactions\u003csup\u003e6\u003c/sup\u003e. For example, a thin liquid-like layer can serve as an intermediate for the mass transport from metal nanoparticles (NPs) to the liquids, differing from the traditional transfer behavior\u003csup\u003e7\u003c/sup\u003e. Similarly, the hot electron transfer has been found to be faster at the solid\u0026thinsp;\u0026minus;\u0026thinsp;liquid interfaces than that at the solid\u0026thinsp;\u0026minus;\u0026thinsp;gas ones in the Pt/n-Si system\u003csup\u003e8\u003c/sup\u003e. The oxidation of isopropyl alcohol to acetone catalyzed by platinum has been reported to be enhanced at the solid/liquid interfaces upon comparison with that at the solid/gas ones\u003csup\u003e9\u003c/sup\u003e, while the enhancement in the oxidation of alloys (e.g., nickel\u0026ndash;chromium) occurs with the existence of water-vapor interfaces compared to that of pure oxygen\u003csup\u003e10\u003c/sup\u003e. Similar increment of etching rates has been observed in the solid\u0026ndash;liquid\u0026ndash;gas interfaces formed at the gold nanorods in liquids with the assistance from the adsorbed oxygen\u003csup\u003e11\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eDespite the aforementioned progress achieved in the leading materials with the solid form, the behaviors of liquid nanodroplets at different interfaces have been relatively less reported and understood. Unraveling the fundamental physicochemical processes of interfacial liquid droplets offer unique and promising applications in the fields including nanoreactors\u003csup\u003e12\u003c/sup\u003e, microfluidics\u003csup\u003e13\u003c/sup\u003e, nanomotors\u003csup\u003e14\u003c/sup\u003e, nanotransporters\u003csup\u003e15\u003c/sup\u003e, 3D additive manufacturing\u003csup\u003e16\u003c/sup\u003e, nanowelding\u003csup\u003e17\u003c/sup\u003e, nanowetting\u003csup\u003e18\u003c/sup\u003e, spraying\u003csup\u003e19\u003c/sup\u003e, and flexible/wearable devices\u003csup\u003e20\u003c/sup\u003e. It has been shown that the motion velocities of water microdroplets are increased dramatically on the superhydrophobic interfaces\u003csup\u003e21\u003c/sup\u003e, and the chemical reactions can be also facilitated on the surface of liquid droplets\u003csup\u003e22\u003c/sup\u003e as well as the solid-liquid interfaces\u003csup\u003e23,24\u003c/sup\u003e. Moreover, the introduction of additional gradient external fields including electric force, temperature, light and surface free energy would further modulate the dynamical processes of droplets. For instance, the water droplets demonstrate the exceptional uphill motion through tuning the gradient surface energy caused by the interfacial morphologies\u003csup\u003e25\u003c/sup\u003e. Nevertheless, the full picture of nanoscale droplets dynamics from initial formation to subsequent evolution as well as the simultaneous structural/elemental identification remains challenging and unclear, leading to the isolated understanding and even uncertainty in the results. Therefore, direct visualization of the whole evolution of nanodroplets with \u003cem\u003ein-situ\u003c/em\u003e capability is indispensable, which enables a thorough understanding of fundamental interfacial processes at complex multiphase boundaries (e.g., solid\u0026ndash;liquid\u0026ndash;gas and solid\u0026ndash;liquid\u0026ndash;liquid), and further manipulation of the interfacial behaviors at the nanoscale.\u003c/p\u003e \u003cp\u003eHerein, using our previously developed massive cell fabrication method\u003csup\u003e26\u003c/sup\u003e, we successfully encapsulated the HgS nanocrystals (NCs) in gas and liquid environments, and statistically investigated the full evolution dynamics of less-known metal nanodroplets (Hg) at nanoscale solid-gas and solid-liquid interfaces by \u003cem\u003ein-situ\u003c/em\u003e transmission electron microscopy (TEM). The choice of HgS as the studied system was based on the following considerations: i) Facile formation of metal Hg nanodroplets from HgS upon the electron-beam (e-beam) excitation so that the full dynamics from the initial formation (birth) to the later evolutions were allowed; ii) HgS NCs were water soluble, leading to the easy preparation of liquid cells; and iii) Nanoscale saw-tooth morphology of HgS NCs enabled the investigations of motion behavior of the Hg nanodroplets. In the gas cells, the nucleation, growth and coalescence of the voids were observed, while simultaneously the Hg nanodroplets occurred, then moved rapidly on the ratchet surface, and finally coalesced into the large ones through the bridges. Interestingly, in the case of liquid cells, the ink-like liquid Hg jetted from the solid-liquid (HgS-water) interface. Determined by the competition between the reductive electrons and the oxidative species derived from the radiolysis of liquid, consecutive ink-jetting behavior happened with the interval time between two neighboring ones in the range from several to several tens of seconds. Further \u003cem\u003eex-situ\u003c/em\u003e control experiments verified the above behaviors. The underlying mechanisms for the above phenomena were thoroughly discussed.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStructural characteristics of HgS for gas/liquid cell studies\u003c/h2\u003e \u003cp\u003eChiral α-HgS NCs were prepared by the seed-mediated epitaxial growth technique, as detailed in \u003cspan refid=\"Sec12\" class=\"InternalRef\"\u003eMethods\u003c/span\u003e section. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea shows the helical arrangement of Hg and S atoms along the crystallographic \u003cem\u003ec\u003c/em\u003e axis in HgS with the \u003cem\u003eP\u003c/em\u003e3\u003csub\u003e1\u003c/sub\u003e21 space group, which represents an atomic-scale primary chiral unit. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb shows the as-synthesized NCs with the length and width of ~\u0026thinsp;120 nm and 60 nm. The measured interplanar spacing of 3.359 \u0026Aring; in high-resolution TEM corresponds to the (101) plane of α-HgS that is indicated from the diffraction pattern (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, inset). The chirality of the NCs would be tuned through the enantioselective synthesis strategy, where an example is demonstrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec. Using the massive cell fabrication method developed recently, we have succeeded in encapsulating the HgS NCs in gas and liquid environments for later dynamics studies. The structural evolution of the HgS nanostructures in gas and liquid is visualized by in-situ TEM (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). An electron beam (e-beam) is utilized to excite the NCs, while simultaneously the structural information involved during the dynamical processes is recorded by a digital camera in real-time. The schematic diagram of the gas/liquid cell is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee (top). The difference in fabrication was due to the addition of the glycerol (retard the volatilization of water) into the core liquid precursor during electrospinning of the liquid cells. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee (bottom) presents a typical TEM image of the as-prepared cell with a HgS NC inside. With the e-beam excitation, a certain number of dark clusters (marked in the area A) were steadily formed on the NC (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ef, top). The dark clusters were composed of Hg nanodroplets, which were verified by the energy dispersive X-ray spectroscopy (EDS). When the HgS NC located in vacuum (without the isolation by the cell), however, only the morphological framework remained after the long-term e-beam irradiation because of the evaporation of Hg droplets (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ef, bottom). The EDS analysis suggested that the remaining white feature (marked in the area B) was almost from S, verifying the evaporation of Hg.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eStructural evolution of HgS NCs in gas cell\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows a series of TEM images depicting the nucleation and growth dynamics of Hg nanodroplets in the gas cell (see Supplementary Movie 1 for details). Herein, for the sake of convenience, the time zero (0 s) was defined as the moment of initiating the video recording (the initial TEM alignment was operated under a low dose rate of ~\u0026thinsp;50\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s so that the structural evolution was not excited). At a high dose rate of 3240\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea), abundant voids (white features marked by the rectangles) arose rapidly, accompanied with the appearance of Hg nanodroplets (marked by the circles) after e-beam excitation for 2 s. As the irradiation time elapsed (e.g., 15 and 19 s), the voids wriggled and coalesced when they met. The voids grew up after coalescence (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb, a typical example given at 270 s), and later turned into a crack-like feature at 380 s (marked by the rectangle) through lengthening (310 s) and coalescence processes (365 s). Different from the phenomenon observed in vacuum\u003csup\u003e27\u003c/sup\u003e, the small Hg nanodroplets gradually grew up during the e-beam excitation. Upon comparison of the TEM images at 410 s and 720 s (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, indicated by the arrows), it showed that the Hg nanodroplets were further enlarged to a size of approximately 10\u0026ndash;15 nm due to the coalescence. At this stage, the droplets became relatively stable. When the dose rate was further increased to 7350\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s, however, the Hg nanodroplets moved again and became larger at 1150 s. Ultimately, a big and stable nanodroplet with a size of ~\u0026thinsp;70 nm appeared at 1250 s (the inset was a view of the whole HgS morphology), which was much larger than that observed in vacuum (typically 5\u0026ndash;7 nm in size). The dynamical evolutions of the voids and Hg nanodroplets are schematically illustrated in the rightmost column of the figure.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eRather than the enlargement of Hg nanodroplets inside the gas cells, we also noted that the big nanodroplets could suddenly fade away if the cells were broken intentionally. As depicted in Supplementary Fig.\u0026nbsp;1, the Hg nanodroplets gradually grew as the irradiation time elapsed and had a size of ~\u0026thinsp;40 nm at 480 s. These nanodroplets suddenly began to fade away from 480 s, and almost disappeared at 515 s. Such evaporation and disappearance of the nanodroplets was similar to that observed in the vacuum condition\u003csup\u003e27\u003c/sup\u003e, which was due to the structural breakage of the gas cell that became vacuum environment in the TEM chamber.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eDetailed Evolution of voids and Hg droplets in gas cell\u003c/h2\u003e \u003cp\u003eTo gain detailed insight into the dynamical behavior of voids and Hg droplets, the dose rate-dependent experiments were carried out, as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. As the dose rate was increased from 2020 to 7310\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s, the stable size of Hg droplets increased from ~\u0026thinsp;1.6 to 40.7 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). It indicates that Hg droplets would stabilize with an appropriate size at each specific dose rate and higher dose rate facilitated the formation of larger droplets in the closed gas cell. The growth speed of Hg nanodroplets was estimated to be from ~\u0026thinsp;0.004 nm/s to 0.162 nm/s when the dose rate was increased from 2020 to 4810\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s (inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb shows the distribution characteristics of Hg and S elements as a function of the dose rate. Five different areas were selected to analyze the elemental distribution of the samples after the e-beam irradiation (an example was given in the inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb), revealing the diffusion behavior of Hg nanodroplets. Upon comparison of Hg/S ratio at different dose rates, large variation was observed under the high dose rate, which was due to the random distribution of fewer Hg droplets with relatively big size (refer to the TEM image at 1150 or 1250 s in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe movement speeds of voids and Hg droplets at different dose rates were then quantitatively estimated, as presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec. In the case of voids, the rate of movement increased from ~\u0026thinsp;0.19 to 5.04 nm/s with the enhancement of dose rate from 688 to 3520\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s (inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). Similarly, the Hg nanodroplets exhibited the movement speed from ~\u0026thinsp;0.08 to 2.91 nm/s with the increment of dose rate from 1060 to 3520\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s. As the dose rate was further increased to a higher level (4340\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s), the Hg nanodroplets moved much faster and had a velocity of ~\u0026thinsp;55.94 nm/s. Finally, they would reach the velocity of 65.14 nm/s under the dose rate of 7340\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s.\u003c/p\u003e \u003cp\u003eWe noticed that the voids and Hg droplets grew after coalescence, which were detailed in Supplementary Movies 2 and 3. Figures\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee are the sequential TEM images extracted from the videos, showing the coalescence processes of the voids and Hg droplets, respectively. At 259 s, several voids were seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed (marked by the squares). After further e-beam irradiation for 10 s, a bridge began to appear between two neighboring voids with a distance of ~\u0026thinsp;18 nm (marked by the rectangles). Such bridges became clearly visible during the following period of 30 s. Subsequently, the large voids were formed at 324 s as a result of the coalescence. The large voids would finally turn into a long crack-like feature (349 s). On the other hand, the coalescence was also realized through the nanobridges between two Hg droplets (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee). Initially (520 s), the two droplets (marked by the circles) were separated with a distance of ~\u0026thinsp;8 nm. When they approached at 6 nm, a bridge (marked by the ellipse) appeared at this stage (555 s). The bridge got wider with the time (565 s), which induced the subsequent coalescence of the two droplets (585 s). As the time elapsed (605 s), the coalesced droplet continued changing its shape to further reduce the surface energy.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eInk-jetting phenomenon of HgS NCs in liquid cell\u003c/h2\u003e \u003cp\u003eTo study the Hg behavior at the solid-liquid interface, the structural evolution of HgS NCs in liquids was conducted. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea shows the evolution of a single NC from a series of sequential TEM images (Supplementary Movie 4). The experiment was operated under a dose rate of ~\u0026thinsp;5200\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s. Under the e-beam excitation (20 s), the voids were formed rapidly with the appearance of some small Hg nanodroplets (see details in Supplementary Fig.\u0026nbsp;2). The voids were eventually turned into the large ones (marked by the rectangle) through the coalescence process (e.g., 312 s and Supplementary Fig.\u0026nbsp;3). Different from the phenomena observed in the gas cell, the structural evolution of HgS in water underwent periodic jetting of Hg liquid, hereafter named as the ink-jetting event (such like the \u0026ldquo;ink-jetting\u0026rdquo; from cuttlefish). Upon irradiation for a relatively long time, the first ink-jetting began to appear at 338 s (marked by the circles). It spread quickly during the following seconds and then finished at 346 s. Within the next tens of seconds, the ink-jetting additionally occurred five times (the commence and end processes similar as that displayed above) and finally ended at 470 s. The beginning \u003cem\u003et\u003c/em\u003e\u003csub\u003es\u003c/sub\u003e and finish time \u003cem\u003et\u003c/em\u003e\u003csub\u003ef\u003c/sub\u003e of each ink-jetting event are summarized in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb. From the inset, it can be seen that the period of spanning a whole ink-jetting process \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\text{∆}\\text{t}\\text{}\\text{=}{\\text{t}}_{\\text{f}}\\text{-}{\\text{t}}_{\\text{s}}\\)\u003c/span\u003e\u003c/span\u003e was in the range of several to tens of seconds. Note that the time needed to initiate the ink-jetting event was decreased with the increase of the dose rate (Supplementary Fig.\u0026nbsp;4). Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec presents the dose rate-dependent jetting speed of the ink feature. The jetting rate of the ink increased from ~\u0026thinsp;2.7 to 16.4 nm/s with the increment of dose rate from 3620 to 8780\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s. The Hg/S ratios under the different dose rates are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed (the selected areas for EDS are given in the inset), revealing the distribution of Hg and S elements after the ink-jetting behavior. The variation of the Hg/S ratios was not significant under different dose rates, which was different from the overall trend observed in the gas environment (random distribution of large droplets displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWhen multiple HgS NCs existed in the liquid cell, similar continuous ink-jetting phenomenon also occurred (Supplementary Fig.\u0026nbsp;5). During the e-beam irradiation, the voids preferentially arose and grew up, e.g., at the stages of 65 s and 107 s. The first ink-jetting began at 138 s, then spread and lasted for several seconds, and finally finished at 150 s. Afterwards, the second one was triggered at 169 s. The ink-like feature became larger in size at 170 and 172 s, and eventually stopped at 182 s. The last one (the seventh) was evolved in a similar way (began and finished at 282 s and 294 s, respectively). Ultimately, the HgS NC became relatively stable and showed no obvious morphological change. Note that other neighboring NCs also experienced the similar ink-jetting, forming an agglomerated particle at the end (the inset image at 294 s).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eVoid nucleation, growth, and coalescence\u003c/h2\u003e \u003cp\u003eIn the experiments we observed the evolution of voids that was categorized into the nucleation, growth, and coalescence processes. It has been documented that the voids would be formed through the thermal heating\u003csup\u003e28\u003c/sup\u003e, local stress concentrators caused by extended defects (e.g., dislocations and grain boundaries)\u003csup\u003e29\u003c/sup\u003e, Kirkendall effect\u003csup\u003e30\u003c/sup\u003e and atomic displacement induced vacancy zones\u003csup\u003e31\u003c/sup\u003e. The e-beam-induced temperature rise was normally in the range of several degrees\u003csup\u003e32,33\u003c/sup\u003e, indicating that heating did not dominate the formation of voids. The local stress concentrators and the Kirkendall effect might not mainly account for the void formation either, because no grain boundaries and/or diffusion couple with different rates were involved during the process. In the absence of material discontinuities, on the other hand, the direct transfer of e-beam energy to atoms during collision may be large enough to knock them out of their lattice sites, creating the vacancies so that the condensation of vacancy clusters induces the voids. On the basis of both energy and momentum conservation, the maximum kinetic energy \u003cem\u003eE\u003c/em\u003e\u003csub\u003eA\u003c/sub\u003e transferred from an electron to an atom through collision is estimated using the following equation,\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:{\\text{E}}_{\\text{A}}\\text{}\\text{=}\\text{}\\text{561}\\text{\u0026epsilon;}\\text{}\\left(\\text{\u0026epsilon;}\\text{}\\text{+}\\text{}\\text{2}\\right)\\text{}\\text{/}\\text{}\\text{A}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{A}\\)\u003c/span\u003e\u003c/span\u003e is the weight of atom and \u003cem\u003eε\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eE\u003c/em\u003e/(\u003cem\u003emc\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e), \u003cem\u003eE\u003c/em\u003e is the original energy of electron in TEM with 200 kV accelerating voltage, \u003cem\u003em\u003c/em\u003e is the mass of electron, and \u003cem\u003ec\u003c/em\u003e is velocity of light. For the typical 200 keV e-beam in TEM, the \u003cem\u003eE\u003c/em\u003e\u003csub\u003eA\u003c/sub\u003e values were calculated to be 2.62 and 16.37 eV for Hg and S, respectively. Upon comparison to the vacancy formation energies \u003cem\u003eE\u003c/em\u003e\u003csub\u003ev\u003c/sub\u003e of 4.5 and 7.8 eV for Hg and S, it indicates that it was easier for S atoms to be knocked out than that for Hg atoms. Surprisingly, according to the EDS analysis the loss of Hg was more than that of S element (Supplementary Fig.\u0026nbsp;6), which was owing to the occurrence, movement, and evaporation of Hg droplets (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Such evolution of Hg droplets would further offer localized reduction in displacement energy for S, energetically favoring the vacancy clustering to facilitate the evolution of voids.\u003c/p\u003e \u003cp\u003eIn the next stage, the dynamical evolution includes the simultaneous growth and coalescence of existing voids as well as the formation of few new ones. Compared to the nucleation of new ones, the small voids tended to add into the existing voids and to merge to form the large ones, which was probably driven by the reduction of the total energy of the system. Interestingly, unlike the direct coalescence of voids, e.g., the behavior reported in the Bi nanoparticles induced by heating, the coalescence between two neighboring voids in the HgS NCs was achieved by the bridge with ~\u0026thinsp;18 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Ultimately, the large voids turned into a long crack-like feature to further lower the total energy. Such feature preferentially propagated along the \u0026lt;\u0026thinsp;001\u0026thinsp;\u0026gt;\u0026thinsp;direction of the crystal due to the fewer number of bonds bridging unit cells perpendicular to this direction. In this work, the structural evolution of the crystal tended to form the voids instead of the volume contraction so that the framework was maintained. This was probably due to the thermodynamic preference for reduction of the total surface energy of the voids greater than the crystal surface energy.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eFormation, movement and coalescence of Hg nanodroplets\u003c/h3\u003e\n\u003cp\u003eDuring the e-beam excitation of HgS semiconductor, a number of electron-hole (e\u0026ndash;h) pairs are generated within an excitation volume. For a 200 kV e-beam with the typical current of 1.2 nA used here, the local rate of carrier pair generation was calculated to be approximately 3.10 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e pairs per second in the HgS NC (Supplementary Fig.\u0026nbsp;7, Supplementary Tables\u0026nbsp;1\u0026ndash;2 and Supplementary Notes). The utilization of such generated electrons was then roughly estimated. As presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, about three discernible Hg nanodroplets with a diameter of ~\u0026thinsp;2 nm (~\u0026thinsp;7.26 \u0026times; 10\u003csup\u003e3\u003c/sup\u003e atoms) formed at 2 s while ten bigger nanodroplets (diameter of ~\u0026thinsp;10 nm) appeared at 400 s which contained about 3.02 \u0026times; 10\u003csup\u003e6\u003c/sup\u003e Hg atoms. Within these e-beam excitation periods, the number of generated electrons were 6.20 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e and 1.24 \u0026times; 10\u003csup\u003e8\u003c/sup\u003e for 2 s and 400 s, respectively. Despite the rough estimation, it provided a pictorial understanding for the formation of Hg nanodroplets (Hg\u003csup\u003e2+\u003c/sup\u003e + 2e \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\to\\:\\)\u003c/span\u003e\u003c/span\u003e Hg), namely, the formation of the 2 nm (~\u0026thinsp;2.3%) and 10 nm (~\u0026thinsp;4.9%) nanodroplets only consumed several percent of the reductive electrons, whereas most of the carriers were recombined in the material.\u003c/p\u003e \u003cp\u003eAfter the formation, those Hg nanodroplets exhibited relatively large movement speed of ~\u0026thinsp;56 nm/s at the dose rate of 4340\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e\u0026middot;s, in comparison to that of ~\u0026thinsp;5\u0026ndash;10 nm/s observed for the Bi nanodroplets\u003csup\u003e34\u003c/sup\u003e. Although the movement of metal nanodroplets has been rarely reported, several mechanisms about the driving forces originated from the gradient fields including temperature\u003csup\u003e21\u003c/sup\u003e, surface energy\u003csup\u003e35\u003c/sup\u003e, electric field\u003csup\u003e36\u003c/sup\u003e and light field\u003csup\u003e37\u003c/sup\u003e have been proposed for other common liquid droplets (e.g., water). Those factors might not be applicable or play the essential role for the phenomena observed in this work. It has also been shown that the ratchet surface leaded to the propulsion of the liquids, which was driven by the viscous force between the solid/liquid interface due to the Leidenfrost effect\u003csup\u003e38\u003c/sup\u003e. The HgS nanocrystals in our work adopted a saw-tooth morphological feature so that the Hg nanodroplets preferred to curve concavely near the tops of the ridges while presenting the convex characteristics elsewhere (Supplementary Fig.\u0026nbsp;8). In this scenario, we speculated that such ratchet surface may contribute to the fast movement of the Hg nanodroplets. During the e-beam-induced reduction of Hg, the nucleation of the nanodroplets occurred once the vapor pressure of Hg exceeded the saturated one. Such variation in the surface curvature would generate a pressure differential Δ\u003cem\u003ep\u003c/em\u003e between the concave ridge and the neighboring convex position, forming a net force to drive the motion of the nanodroplet (Supplementary Fig.\u0026nbsp;8). Such a pictorial understanding was again verified by the fact that the glide velocity of the Hg nanodroplets increased dramatically at the high e-beam dose rates since more Hg vapor was formed upon the irradiation (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDuring the movement, the Hg nanodroplets would coalesce with a relatively large distance of ~\u0026thinsp;5 nm through the bridges (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), which was different from that observed in other systems. For example, the Bi nanodroplets underwent a sudden coalescence on the SrBi\u003csub\u003e2\u003c/sub\u003eTa\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e9\u003c/sub\u003e platelet\u003csup\u003e39\u003c/sup\u003e, while the fusion or coalescence of Au nanocrystals was realized by the nanochannel with a critical spacing of less than 1 nm\u003csup\u003e40\u0026ndash;42\u003c/sup\u003e. Moreover, the coalescence of nanobubbles in liquids was observed to occur within a distance of ~\u0026thinsp;2 nm between two bubbles\u003csup\u003e43\u003c/sup\u003e. In this work, the e-beam irradiation induced the reduction of Hg\u003csup\u003e2+\u003c/sup\u003e to Hg on the HgS NCs. As the time elapsed, the accumulation of Hg atoms might create the atomic chains accordingly, resulting in the formation of relatively long bridges that finally leaded to the coalescence between the nanodroplets.\u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eMechanism for continuous ink-jetting behavior\u003c/h2\u003e \u003cp\u003eIt is known that the irradiation of water by the electron beam generally generates a variety of radiolysis products, including the common oxidative \u0026bull;OH, H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e and reductive solvated electron e\u003csub\u003eh\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e species\u003csup\u003e44\u003c/sup\u003e. The steady-state concentrations of the radiolysis species were calculated and summarized (Supplementary Tables\u0026nbsp;3, 4, 5), presenting that the concentration of the oxidative species was higher than that of the reductive ones. Meanwhile, the oxidative species possess very high reduction potentials (Supplementary Table\u0026nbsp;6), which have been reported to play the vital role for etching the nanostructures (especially metals) in liquids\u003csup\u003e31,45\u0026ndash;48\u003c/sup\u003e. Despite the inevitable existence of slight etching, the HgS semiconductor studied here demonstrated the distinct behavior from that was shown in the metal nanostructures (almost pure etching).\u003c/p\u003e \u003cp\u003eDifferent types of scavengers were designed to suppress a certain number of specific species so that the dominated ones for the ink-jetting phenomenon would be clarified. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea shows the sequential TEM images in the electrospun liquid cells with the addition of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e (scavenger for reductive species). In this case, the e-beam-induced oxidative species would predominate. The HgS NCs were gradually etched and more cavity feature was formed with the increment of time. No ink-jetting phenomenon was observed even during the long irradiation for ~\u0026thinsp;300 s. The above behavior was further validated in the thin carbon liquid cells with the same addition of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb). Obvious contrast from the bubbles was observed, manifesting the liquid environment inside the carbon liquid cell (Supplementary Fig.\u0026nbsp;9). Similar etching phenomenon was also observed as the time elapsed to several hundreds of seconds. Additional \u003cem\u003eex-situ\u003c/em\u003e experiments were designed to distinguish the etching effect from either H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e or \u0026bull;OH (see Methods for details). Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec depicts the TEM images of the HgS NCs treated mainly by \u0026bull;OH. The morphological change was seen at 10 min and it became obvious after 30 min. Most parts of the NCs were etched off after 180 min, resulting in the complete collapse of the initial bipyramid structure. In contrast, the HgS NCs with the addition of pure Co\u003csup\u003e2+\u003c/sup\u003e or H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e presented no obvious morphological change at the same time scale (Supplementary Fig.\u0026nbsp;10). Upon comparison of the above results, it indicates that the \u0026bull;OH plays the dominant role in etching the HgS NCs.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed shows the time-dependent TEM images of the ink-jetting phenomenon in the electrospun liquid cells with the addition of methanol (scavenger for oxidative species, Supplementary Movie 5). Similar to the structural evolution of HgS NCs in water, the voids arose rapidly and the ink-jetting phenomenon occurred consecutively. Distinctly, the first ink-jetting occurred at ~\u0026thinsp;66 s, which was significantly shorter than that in the water condition (~\u0026thinsp;314 s). Meanwhile, the interval time\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\text{∆}\\text{t}{\\prime}\\text{}\\text{=}{\\text{}\\text{t}}_{\\text{n}}\\text{-}\\text{}{\\text{t}}_{\\text{n-1}}\\)\u003c/span\u003e\u003c/span\u003e between each ink-jetting event also became shorter, e.g., the fifth jetting behavior was finished within only\u0026thinsp;~\u0026thinsp;4 s. Given the nature of oxidative scavenger in the case of methanol, it suggests that the reductive electrons might play the key role for the continuous ink-jetting phenomenon. This was further evidenced by the fact that the Hg nanodroplets immediately nucleated under the reductive environment after the e-beam excitation for 2 s in the gas cells with the absence of \u0026bull;OH (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). For the case of the liquid cells, the longer time needed to trigger the ink-jetting (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, 338s) indicates that part of the reductive electrons was consumed by the oxidative species and the long-time accumulation of the sufficient electrons therefore allowed the subsequent ink-jetting.\u003c/p\u003e \u003cp\u003eBased on the above discussion, a competition exists for the reduction of Hg\u003csup\u003e2+\u003c/sup\u003e to the formation of Hg droplets, i.e., the reductive electrons promote such behavior whereas the oxidative species inhibit it. Once the accumulated electrons reach the threshold value during such competition process, the ink-jetting behavior occurs. Since the reductive electrons are consumed in each reduction-involved ink-jetting process, a certain amount of time would be thereby required to accumulate enough electrons for the next jetting behavior. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ee shows the relationship between the e-beam irradiation time and the ink-jetting frequency under different liquid conditions. At each frequency, the irradiation time needed to trigger the ink-jetting under the addition of methanol was shorter than that in the water. The interval time between two sequential ink-jetting processes is quantitatively displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ef. Compared to the interval time of ~\u0026thinsp;11\u0026ndash;22 s in water, the time span under the addition of methanol was significantly shortened (~\u0026thinsp;3\u0026ndash;6 s). The phenomenon was ascribed to the consumption of a certain number of oxidative species through the addition of methanol. In this scenario, more electrons had the chance of being involved in the reduction process, leading to the shortened time for triggering the ink-jetting behavior.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eSchematic diagram of nanodroplet dynamics in gas and liquid cells\u003c/h2\u003e \u003cp\u003eThe overall evolution pictures of Hg Nanodroplets in the gas and liquid cells are schematically summarized in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. In the gas cells (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea), the direct transfer of e-beam energy to the Hg and S atoms knocks them out of the lattice sites, creating a large number of the vacancies. The condensation of the vacancy clusters induces the voids, which is also accompanied by the appearance of Hg nanodroplets due to the reduction of Hg\u003csup\u003e2+\u003c/sup\u003e to Hg. Subsequently, the voids gradually grow up after coalescence through the bridges, which further turn into the crack-like structure preferentially along the \u0026lt;\u0026thinsp;001\u0026thinsp;\u0026gt;\u0026thinsp;long-axis direction. Meanwhile, the Hg nanodroplets move rapidly, and come into coalescence through the bridges when they are close each other, forming the bigger ones accordingly. With the continuous coalescence process, the large droplets are finally formed and stay relatively stable on the substrate.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn the case of liquid cells (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb), the voids also arise rapidly in the preliminary stage upon the e-beam excitation, which are evolved into the large ones as the time elapses. Compared to that in the gas cells, distinctly, some smaller Hg nanodroplets appear in the early stage, but without the apparent growth. After the long-time excitation so that the accumulated electrons achieve the threshold, the ink-jetting behavior begins to occur. Such ink-like feature spread, and then becomes less obvious at the later stage. After a certain time of additional e-beam excitation, the second ink-jetting appears once the reaccumulation of the reductive electrons becomes sufficient for triggering such behavior. In this regard, the continuous the ink-jetting behaviors become feasible, with the interval time of two neighboring ones depending on the competition between the reductive electrons (accumulation) and the oxidative species (consumption of electrons). Ultimately, a stable liquid Hg layer is formed after the several ink-jetting processes at a certain dose rate.\u003c/p\u003e \u003cp\u003eIn summary, the distinct evolution dynamics of the Hg nanodroplets mediated at the solid-gas and solid-liquid interfaces were directly visualized and statistically investigated by \u003cem\u003ein-situ\u003c/em\u003e TEM. Upon exposure to e-beam in the gas cells, the voids and Hg nanodroplets nucleated and grew up, which were then coalesced into the large ones through the nanobridges. The voids could be further evolved into the crack-like structure preferentially along the \u0026lt;\u0026thinsp;001\u0026thinsp;\u0026gt;\u0026thinsp;direction of the HgS solid substrate. The Hg droplets moved fast at the solid-gas interface and finally became relatively stable at each dose rate, which was distinct from the evaporation behavior observed at the solid-vacuum interface. In contrast to the typical behavior of the voids and Hg nanodroplets observed at either solid-gas or solid-vacuum interface, statistical results revealed the occurrence of the ink-jetting phenomenon in the liquid cells. Two competitive factors governed the interval time between the neighboring ink-jetting events, namely, the reductive electron species facilitated the shortening of such period while the oxidative species like \u0026bull;OH acted in the opposite manner. These phenomena were further verified by the \u003cem\u003eex-situ\u003c/em\u003e experiments with the addition of additional H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e or methanol. Our results contribute to advance a fundamental understanding of the full and unique evolution picture of liquid metal nanodroplets at nanoscale solid-gas and solid-liquid interfaces, and provide the experimental approach of potentially modulating droplets behavior with controllable functionality through interface engineering.\u003c/p\u003e \u003c/div\u003e "},{"header":"Methods","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003cp\u003e \u003cb\u003eSynthesis of HgS seeds.\u003c/b\u003e The HgS seed nanoparticles (NPs) were synthesized based on a wet-chemical method. Specifically, 128 mg of Hg(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026middot;H\u003csub\u003e2\u003c/sub\u003eO was added into 20.0 mL of deionized water in a round-bottom flask, followed by the dropwise addition of 4 mL of D-form penicillamine aqueous solution (0.09 M) under stirring to obtain a colorless solution. Then, 0.6 mL of NaOH aqueous solution (2 M) was added into the above colorless solution. After further stirring for 2 min, 2.0 mL of thioacetamide solution (0.18 M) was added into the mixture solution. The flask was sealed and placed in a 38 \u003csup\u003eo\u003c/sup\u003eC water bath for 15 h under stirring. After the reaction, the seed NPs were collected by centrifugation at 6000 rpm for 10 min, washed three times with isopropanol, and re-dispersed in 5.0 mL of deionized water for further use.\u003c/p\u003e \u003cp\u003e \u003cb\u003eEpitaxial growth of HgS NCs.\u003c/b\u003e Chiral α-HgS NCs were prepared by the seed-mediated epitaxial growth method using the above as-synthesized seeds. Before the epitaxy, a Hg precursor solution was prepared by the dissolution of 74.4 mg Hg(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026middot;H\u003csub\u003e2\u003c/sub\u003eO into 7.2 mL of deionized water followed by the addition of 1.8 mL of D-penicillamine aqueous solution (0.09 M), whereas a S precursor solution was obtained by dissolving 19.8 mg of thioacetamide in 10 mL of deionized water. For a typical epitaxial growth, 50 \u0026micro;L of HgS seeds colloidal solution was dispersed into 5 mL of deionized water in a three-neck round-bottom flask submerged in the 38 \u003csup\u003eo\u003c/sup\u003eC water bath. 1.0 mL of D-penicillamine aqueous solution (0.09 M) and 0.6 mL of NaOH aqueous solution (2 M) were dropwise added into the flask under stirring. Subsequently, the as-prepared Hg and S precursor solutions were slowly injected into the flask by a syringe pump with an injection rate of 1.0 mL/h for 4 h. After the reaction, the orange precipitates were obtained by centrifugation at 6000 rpm for 10 min, washed three times with isopropanol and finally dispersed in x mL of deionized water for later studies.\u003c/p\u003e \u003cp\u003e \u003cb\u003eChirality and surface profile characterization.\u003c/b\u003e The chirality of HgS samples was characterized by CD spectroscopy. The CD spectra were obtained on a JASCO J-1500 spectropolarimeter with an optical length of 10 mm at 293.15 K. Atomic force microscopy (AFM) was used to reveal the surface profiles of the HgS NCs (FastScan Bio, Bruker, USA).\u003c/p\u003e \u003cp\u003e \u003cb\u003eEx-situ observation of etching behavior.\u003c/b\u003e To investigate the effect from the oxidative species, the Fenton reaction was performed to produce the \u0026bull;OH radicals. Briefly, 30 mg of CoCl\u003csub\u003e2\u003c/sub\u003e power was ultrasonically dispersed into 10 mL of HgS suspension (0.1 mg/mL). The Fenton reaction was triggered by the addition of 0.5 mL of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e into the above solution at room temperature under dark environment with stirring. The Fenton reaction formula is shown as follows,\u003c/p\u003e \u003cp\u003eCo\u003csup\u003e2+\u003c/sup\u003e + H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e \u0026rarr; Co\u003csup\u003e3+\u003c/sup\u003e + OH\u003csup\u003e\u0026minus;\u003c/sup\u003e + \u0026bull;OH (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e0.5 mL of suspension was collected at each given reaction time and added into a test tube containing 1 mL of methanol which was used to terminate the Fenton reaction. Finally, a drop of the above suspension was directly dropped onto the carbon film-coated grid for TEM imaging.\u003c/p\u003e \u003cp\u003eWe also prepared the samples with the addition of only either H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e or CoCl\u003csub\u003e2\u003c/sub\u003e to distinguish the effect from the above \u0026bull;OH radicals. 5 mL of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e or 30 mg of CoCl\u003csub\u003e2\u003c/sub\u003e power was added into 10 mL of HgS suspension (0.1 mg/mL) at room temperature, which was placed under dark environment with stirring. The other procedures were the same to that presented in the above one. The as-prepared samples were finally used to the later TEM characterization.\u003c/p\u003e \u003cp\u003e \u003cb\u003eLiquid and gas cell fabrication.\u003c/b\u003e The liquid cells were prepared by a coaxial electrospinning technique reported in our previous study. Frist, two kinds of liquid precursors (shell and core liquid precursors) were prepared, i.e., the shell liquid precursor was obtained by dissolving 3 g of polyvinyl acetate (PVAC) in 20 mL of dimethyl carbonate (DMC) under stirring for 8 h, while the core liquid precursor was prepared by dispersion of 1 mg of the as-prepared chiral α-HgS NCs into 10 mL of deionized water. Note that 0.05 g of glycerol was also added into the core liquid precursor to reduce the water volatilization during electrospinning. Then, the core and shell liquid precursors were pumped into two syringes for electrospinning with the flow rates of the core and shell liquids set at 2.0 \u0026micro;m/s and 7.8 \u0026micro;m/s, respectively. The applied voltage and roller speed were set as 15 kV and 60 r/min, respectively. Finally, the copper grids with ~\u0026thinsp;20 nm thick carbon films were directly used to collect the fibers for the ready-to-use liquid cell TEM (collection time was 45 s). For the gas cell fabrication, the procedures were almost the same but without the addition of glycerol so that the core water evaporated during electrospinning.\u003c/p\u003e \u003cp\u003eTo investigate the effect of the scavengers on the reductive and oxidative species, the liquid cells with the additional addition of either H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e or methanol were also fabricated by electrospinning. All the electrospinning steps were the same as that shown above, except the preparation of the core liquid precursors. For this preparation, the extra addition of either 0.5 mL of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e or 0.5 mL of methanol into 10 mL of HgS suspension (0.1 mg/mL) was acted as the core precursor.\u003c/p\u003e \u003cp\u003eIn addition, the carbon-film liquid cells were further prepared to verify the phenomena observed in the electrospun ones. Briefly, 0.5 mL of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e was firstly added into 10 mL of HgS suspension (0.1 mg/mL). Then, 1.5 \u0026micro;L of the above suspension was dropped onto one piece of the carbon film-coated grid and subsequently sandwiched by another one face to face. The liquid cells were dried naturally under ambient atmosphere for about 2 h. After the evaporation of excessive liquid solution, the liquid pockets containing the HgS NCs were finally formed between two thin carbon films owing to van der Waals force.\u003c/p\u003e \u003cp\u003e \u003cb\u003eIn-situ TEM visualization of structural dynamics.\u003c/b\u003e Upon the e-beam irradiation, the structural evolution of HgS NCs in the liquid and gas cells under different conditions was in-situ visualized in an FEI Talos F200X TEM operating at 200 kV. The dynamical processes of the e-beam-induced evolution were then recorded by a digital camera. The electron dose rate was tuned in a range of 500-10000\u0026nbsp;e/\u0026Aring;\u003csup\u003e2\u003c/sup\u003e s to ensure the initiation of the structural evolution. To reveal the compositional change during the evolution, the high-angle annular dark-field (HAADF) and EDS techniques in the scanning transmission electron microscopy (STEM) mode were utilized to analyze the elemental composition and distribution under different dynamical stages.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003ch2\u003eAuthor contributions\u003c/h2\u003e \u003cp\u003eB. C. and L. X. conceived the research. L. X. synthesized the materials and performed the TEM experiments. Z. C., Z. L., C. Z., S. P., and Y. L. assisted in the synthesis of HgS and preparation of gas/liquid cells. L. X. and B. C. wrote the manuscript. All authors contributed to the data analysis and discussion.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThis work is supported by the National Natural Science Foundation of China (No. 92061116). The authors also acknowledge the financial support from the Science and Technology Commission of Shanghai Municipality (22ZR1428400) and the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eXie C, Niu Z, Kim D, Li M, Yang P (2020) Surface and interface control in nanoparticle catalysis. Chem Rev 120:1184\u0026ndash;1249\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStamenkovic VR, Strmcnik D, Lopes PP, Markovic NM (2017) Energy and fuels from electrochemical interfaces. Nat Mater 16:57\u0026ndash;69\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJun Y-S, Kim D, Neil CW (2016) Heterogeneous nucleation and growth of nanoparticles at environmental interfaces. Acc Chem Res 49:1681\u0026ndash;1690\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXiao Y et al (2020) Understanding interface stability in solid-state batteries. Nat Rev Mater 5:105\u0026ndash;126\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLuo D, Li X, Dumont A, Yu H, Lu Z-H (2021) Recent progress on perovskite surfaces and interfaces in optoelectronic devices. Adv Mater 33:2006004\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang Y, Cai R, Chen C (2019) The nano-bio interactions of nanomedicines: understanding the biochemical driving forces and redox reactions. Acc Chem Res 52:1507\u0026ndash;1518\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeng X et al (2022) Identification of a quasi-liquid phase at solid\u0026ndash;liquid interface. Nat Commun 13:3601\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee SW, Kim H, Park JY (2023) How hot electron generation at the solid-liquid interface is different from the solid-gas interface. Nano Lett 23:5373\u0026ndash;5380\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu F et al (2019) Catalytic 1\u0026ndash;propanol oxidation on size-controlled platinum nanoparticles at solid-gas and solid-liquid interfaces: significant differences in kinetics and mechanisms. J Phys Chem C 123:7577\u0026ndash;7583\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLuo L et al (2018) Atomic origins of water-vapour-promoted alloy oxidation. \u003cem\u003eNat. Mater.\u003c/em\u003e 17, 514\u0026thinsp;\u0026ndash;\u0026thinsp;518\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang W et al (2022) Solid-liquid-gas reaction accelerated by gas molecule tunnelling-like effect. Nat Mater 21:859\u0026ndash;863\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSwisher JH, Jibril L, Petrosko SH, Mirkin CA (2022) Nanoreactors for particle synthesis. Nat Rev Mater 7:428\u0026ndash;448\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaminski TS, Garstecki P (2017) Controlled droplet microfluidic systems for multistep chemical and biological assays. Chem Soc Rev 46:6210\u0026ndash;6226\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWan J et al (2023) Visualizing facets asymmetry induced directional movement of cadmium chloride nanomotor. \u003cem\u003eNano Lett.\u003c/em\u003e 23, 10132\u0026thinsp;\u0026ndash;\u0026thinsp;10139\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSicard F, Toro-Mendoza J (2021) Armored droplets as soft nanocarriers for encapsulation and release under flow conditions. ACS Nano 15:11406\u0026ndash;11416\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQu M et al (2022) Controlling process instability for defect lean metal additive manufacturing. Nat Commun 13:1079\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu Y et al (2017) Capillary-force-induced cold welding in silver-nanowire-based flexible transparent electrodes. Nano Lett 17:1090\u0026ndash;1096\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChu K-H, Xiao R, Wang EN (2010) Uni-directional liquid spreading on asymmetric nanostructured surfaces. Nat Mater 9:413\u0026ndash;417\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJadidi M, Moghtadernejad S, Dolatabadi A (2015) A comprehensive review on fluid dynamics and transport of suspension/liquid droplets and particles in high-velocity oxygen-fuel (HVOF) thermal spray. \u003cem\u003eCoatings\u003c/em\u003e 5, 576\u0026thinsp;\u0026ndash;\u0026thinsp;645\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu Y et al (2023) Recent advances in inkjet-printing technologies for flexible/wearable electronics. Nanoscale 15:6025\u0026ndash;6051\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrzoska JB, Brochard-Wyart F, Rondelez F (1993) Motions of droplets on hydrophobic model surfaces induced by thermal gradients. Langmuir 9:2220\u0026ndash;2224\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhu C et al (2023) High electric fields on water microdroplets catalyze spontaneous and fast reactions in halogen-bond complexes. J Am Chem Soc 145:21207\u0026ndash;21212\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKoren E et al (2011) Obtaining uniform dopant distributions in VLS-grown Si nanowires. Nano Lett 11:183\u0026ndash;187\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaliakkal CB, Tornberg M, Jacobsson D, Lehmann S, Dick KA (2021) Vapor\u0026ndash;solid\u0026ndash;solid growth dynamics in GaAs nanowires. Nanoscale Adv 3:5928\u0026ndash;5940\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChaudhury MK, Whitesides GM (1992) How to make water run uphill. Science 256:1539\u0026ndash;1541\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu Z et al (2021) Versatile printing of substantial liquid cells for efficiently imaging in situ liquid-phase dynamics. \u003cem\u003eNano Lett.\u003c/em\u003e 21, 6882\u0026thinsp;\u0026ndash;\u0026thinsp;6890\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCao Z, He J, Liu Z, Zhang H, Chen B (2021) Chirality affecting reaction dynamics of HgS nanostructures simultaneously visualized in real and reciprocal space. ACS Nano 15:16255\u0026ndash;16265\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Y et al (2017) In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles. Nat Commun 8:14462\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGerstein G et al (2017) Formation and growth of voids in dual-phase steel at microscale and nanoscale levels. J Mater Sci 52:4234\u0026ndash;4243\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChee SW, Tan SF, Baraissov Z, Bosman M, Mirsaidov U (2017) Direct observation of the nanoscale Kirkendall effect during galvanic replacement reactions. Nat Commun 8:1224\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang X, Jones T, Fan H, Willinger M-G (2016) Atomic-scale observation of irradiation-induced surface oxidation by in situ transmission electron microscopy. Adv Mater Interfaces 3:1600751\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGrogan JM, Schneider NM, Ross FM, Bau HH (2014) Bubble and pattern formation in liquid induced by an electron beam. Nano Lett 14:359\u0026ndash;364\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHauwiller MR et al (2019) Gold nanocrystal etching as a means of probing the dynamic chemical environment in graphene liquid cell electron microscopy. J Am Chem Soc 141:4428\u0026ndash;4437\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi J, Wang Z, Deepak FL (2017) In situ atomic-scale observation of droplet coalescence driven nucleation and growth at liquid/solid interfaces. ACS Nano 11:5590\u0026ndash;5597\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Z et al (2019) Unidirectional self-driving liquid droplet transport on a monolayer graphene-covered textured substrate. ACS Appl Mater Interfaces 11:28562\u0026ndash;28570\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePollack MG, Fair RB, Shenderov AD (2000) Electrowetting-based actuation of liquid droplets for microfluidic applications. Appl Phys Lett 77:1725\u0026ndash;1726\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIchimura K, Oh S-K, Nakagawa M (2000) Light-driven motion of liquids on a photoresponsive surface. Science 288:1624\u0026ndash;1626\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLinke H et al (2006) Self-propelled leidenfrost droplets. Phys Rev Lett 96:154502\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Y et al (2016) Atomic scale imaging of nucleation and growth trajectories of an interfacial bismuth nanodroplet. ACS Nano 10:2386\u0026ndash;2391\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnand U, Lu J, Loh D, Aabdin Z, Mirsaidov U (2016) Hydration layer-mediated pairwise interaction of nanoparticles. Nano Lett 16:786\u0026ndash;790\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYue S, Yuan W, Deng Z, Xi W, Shen Y (2022) In situ TEM observation of the atomic transport process during the coalescence of Au nanoparticles. Nano Lett 22:8115\u0026ndash;8121\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJin B, Sushko ML, Liu Z, Jin C, Tang R (2018) In situ liquid cell TEM reveals bridge-induced contact and fusion of Au nanocrystals in aqueous solution. Nano Lett 18:6551\u0026ndash;6556\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Z et al (2021) Visualization of bubble nucleation and growth confined in 2D flakes. Small 17:2103301\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchneider NM et al (2014) Electron-water interactions and implications for liquid cell electron microscopy. J Phys Chem C 118:22373\u0026ndash;22382\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYe X et al (2016) Single-particle mapping of nonequilibrium nanocrystal transformations. \u003cem\u003eScience\u003c/em\u003e 354, 874\u0026thinsp;\u0026ndash;\u0026thinsp;877\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYan C et al (2022) Facet-selective etching trajectories of individual semiconductor nanocrystals. Sci Adv 8:1700\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYe M et al (2023) Revealing dominant oxidative species in reactive oxygen species-driven rapid chemical etching. Nano Lett 23:7319\u0026ndash;7326\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeng X et al (2024) Unveiling corrosion pathways of Sn nanocrystals through high-resolution liquid cell electron microscopy. Nano Lett 24:1168\u0026ndash;1175\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Metal nanodroplets, Interfaces, In-situ characterization, Liquid cell, Structural dynamics","lastPublishedDoi":"10.21203/rs.3.rs-4865225/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4865225/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eNanodroplets at multiphase interfaces are ubiquitous in nature with implications ranging from fundamental interfacial science to industrial applications including catalytic, environmental, biological and medical processes. Direct observation of the full dynamic evolutions of liquid metal nanodroplets at nanoscale multiphase interfaces offers indispensable insights, however, remains challenging and unclear at the moment. Here, we have fabricated massive ready-to-use gas and liquid cells containing HgS nanocrystals through electrospinning and achieved the statistical investigations of full picture of Hg nanodroplets evolving at solid-gas and solid-liquid interfaces by \u003cem\u003ein-situ\u003c/em\u003e transmission electron microscopy. Upon the electron-beam excitation of HgS in the gas cells, the voids nucleated, grew and then coalesced into the crack-like feature preferentially along the \u0026lt;\u0026thinsp;001\u0026thinsp;\u0026gt;\u0026thinsp;direction through the bridges. Meanwhile, the Hg nanodroplets formed, moved rapidly on the ratchet surface with the velocity of several tens of nm/s and were finally evolved into bigger ones through the nanobridges with the relatively large gap of ~\u0026thinsp;6 nm. Distinctly and surprisingly, mediated by the solid-liquid interface at nanoscale, the liquid Hg with the ink-like feature jetted in the liquid cells. Such ink-jetting behavior would occur multiple times with the intervals from several to several tens of seconds, which was modulated through the competition between the reductive electrons and the oxidative species derived from the radiolysis of liquid by the electron-beam. In-depth understanding of distinct nanodroplets dynamics at nanoscale solid-gas and solid-liquid interfaces offers a feasible approach of designing liquid metal-based nanocomplexes with regulatory interfacial, morphological and rheological functionalities.\u003c/p\u003e","manuscriptTitle":"Filming nanodroplet running and jetting mediated by nanoscale solid-gas and solid-liquid interface","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-09 02:31:44","doi":"10.21203/rs.3.rs-4865225/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"431585d8-dd97-4a64-b16a-85f434a5e6bb","owner":[],"postedDate":"August 9th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":35757415,"name":"Physical sciences/Chemistry/Physical chemistry/Reaction kinetics and dynamics"},{"id":35757416,"name":"Physical sciences/Physics/Chemical physics"}],"tags":[],"updatedAt":"2025-04-18T07:08:06+00:00","versionOfRecord":{"articleIdentity":"rs-4865225","link":"https://doi.org/10.1038/s41467-025-59063-z","journal":{"identity":"nature-communications","isVorOnly":false,"title":"Nature Communications"},"publishedOn":"2025-04-17 04:00:00","publishedOnDateReadable":"April 17th, 2025"},"versionCreatedAt":"2024-08-09 02:31:44","video":"","vorDoi":"10.1038/s41467-025-59063-z","vorDoiUrl":"https://doi.org/10.1038/s41467-025-59063-z","workflowStages":[]},"version":"v1","identity":"rs-4865225","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4865225","identity":"rs-4865225","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}