Tailoring Crystal Phase of High-Entropy Alloy Nanoparticles via Redox-Mediated Engineering

Tailoring Crystal Phase of High-Entropy Alloy Nanoparticles via Redox-Mediated Engineering | 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 Tailoring Crystal Phase of High-Entropy Alloy Nanoparticles via Redox-Mediated Engineering Lei Fu, Yile Zhang, Xingjie Peng, Ziyue Zeng, Wu Zhou, Mengqi Zeng This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8308350/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract High-entropy alloys (HEAs) have already shown great promise for a range of emerging applications, particularly in catalysis, yet their development is constrained by an unresolved challenge: the incompatibility between achieving high configurational entropy and precise crystal phase control. Here, we introduced a redox-mediated kinetic engineering strategy that simultaneously fulfilled both criteria by decoupling nucleation and growth processes. Through staged modulation of reduction potentials—first creating kinetic divergence for phase-specific nucleation, then enabling rapid co-reduction for high-entropy products, we achieved HEAs with tailored crystal structures. Distinct hydrogen evolution performance between different crystalline phases of HEAs unequivocally demonstrated the critical role of crystal phase in determining catalytic properties. The developed synthetic paradigm provided a general route to manipulate HEA phases while preserving high entropy, opening new possibilities for tailored materials design in catalysis and beyond. Physical sciences/Materials science/Materials for energy and catalysis Physical sciences/Nanoscience and technology/Nanoscale materials Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction High-entropy alloys (HEAs) provide an enticing material platform for different applications, achieving remarkable results in various fields such as catalysis 1 , energy storage and conversion 2 , mechanics 3 , and so on 4,5 . The compositional flexibility and complexity of atomic configuration of HEAs exhibits unique potential and appeal in the field of catalysis 6 , 7 . Phase engineering of nanomaterials represents a powerful strategy to precisely modulate their physicochemical properties and optimize functional performance 8 – 11 . Particularly, the construction of metallic nanomaterials with unconventional phases distinct from the thermodynamically stable phases has emerged as an alluring approach to developing highly efficient catalysts 12 – 17 . Therefore, the modulation of the phase structure of HEAs is highly charming, the abundant phase combinations derived from the components and crystal structure offer further opportunities for adjusting their properties to attain the desired applications 18 , 19 . Moreover, the phase engineering of HEAs has garnered significant attention yet remains incompletely explored 6 , 20 – 22 . A fundamental challenge in HEA phase engineering lies in achieving high configurational entropy while maintaining precise control over atomic configurations. On the one hand, considering the differences in atomic radius, electronegativity, and the mixing enthalpy among elements 23 , 24 , phase separation is inclined to take place under near-equilibrium conditions 25 , 26 , claiming synthesis of HEAs in a highly controllable manner is difficult. On the other hand, the extensively investigated approaches of overcoming the immiscibility of elements via high-energy reactions and quenching can readily attain the high-entropy state 18 , 27 , 28 . However, precise atomic positioning cannot be achieved due to the poorly controlled kinetic process resulting from the rapid and intense energy injection. Consequently, there are grand challenges to realizing the phase regulation of HEAs. Herein, we accomplished the phase control of HEAs by the modulation kinetic engineering of the redox potentials of the metal precursors, including the design of the target phase nucleation and the subsequent co-reduction growth of multiple elements. HEAs with face-centered cubic (fcc) and hexagonal close-packed (hcp) phase structures under the same composition and proportion were obtained, realizing the crystal phase control of HEAs. Energy-dispersive X-ray spectroscopy (EDS) analysis and the qualitative analysis of the reduction rate of diverse metal precursors disclosed the reaction mechanism. Moreover, we systematically probed into the impact of the crystal structure of HEAs on the catalytic performance via the electrocatalytic hydrogen evolution reaction (HER). In alkaline conditions, at a current density of 10 mA/cm − 2 , the overpotential of the fcc phase HEA and the hcp phase HEA was 11 mV and 21 mV respectively. This signified that they manifested excellent yet distinct catalytic activities, uncovering the profound significance of HEA phase engineering for catalysis. The crucial part played by atomic-scale structure control was forcefully demonstrated in HEAs. Results The strategy for regulating of phase structures HEAs According to the classical nucleation theory, heterogeneous nucleation possesses a lower energy barrier, facilitating precise manipulation of the growth mode. Furthermore, the crystal structure of an alloy can be determined by that of its nucleus 29 , 30 , 31 . This implies that the structure of the core can be modulated through precise control of the reduction kinetics of the metal precursor, thereby enabling the construction of alloys with diverse phase structures. The reduction reaction of metal ions (M n+ ) can be described by the following: $$\:{M}^{n+}+n{e}^{-}=M$$ The Nernst equation for the reaction in the formula is shown as $$\:{E}_{{M}^{n+}/M}={E}_{{M}^{n+}/M}^{\theta\:}+\frac{RT}{nF}\text{l}\text{n}\left[{M}^{n+}\right]$$ where E, E θ , R, T, n, and F are, respectively, the redox potential, the standard reduction potentials, the gas constant, temperature, the mole number of electrons, and the Faraday constant. E generally controls the morphology and composition of metals or alloys by governing reduction kinetics 32 , 33 . The E θ of metal ions determines their reduction feasibility and rates, thus regulating the transformation efficiency from ionic to metallic states 34 . It is worth noting that the E of metal ions also depends critically on concentration, temperature, and the number of transferred electrons. These parameters not only modulate the thermodynamic driving force but also provide a lever for controlling reduction kinetics. For instance, the reduction rates of metal elements can be influenced by factors such as their valence state, surrounding groups, and the chemical environment, among others 35 , 36 – 38 . By altering these conditions, the relative reduction rates between elements can be modified. In addition, the disparity in the intrinsic reduction rate of metal ions could be surmounted through regularly introducing metal precursors 35 , 39 , 40 . By continuously supplying additional precursors to compensate for consumption, maintaining a steady-state equilibrium of precursor availability. Through precise fine-tuning of precursor reduction potentials to control reduction kinetics, we first intentionally amplified the kinetic disparity to direct crystal phase formation, and subsequently attenuated the difference to facilitate concurrent reduction of multi-metal precursors, ultimately yielding high-entropy state products. In a typical synthesis, as illustrated in Fig. 1 , the Pt and Ru precursors exhibited higher E compared to other metal precursors, driving the formation of their characteristic phase structures. The maintenance of continuous and stable precursor supply made certain uniform reduction rates across all metal elements, realizing the multiple metal precursors co-reduction, and ultimately obtaining HEAs with fcc and hcp phase structures (fcc-RuPtIrRhOs and hcp-RuPtIrRhOs). The Characterization of HEA with different phase structure To investigate the crystal structure of the two synthesized HEAs, X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) analyses were conducted (Fig. 2 ). Figure 2 a, Supplementary Fig. 1 and Table 1 reveal that fcc-RuPtIrRhOs exhibited the typical fcc crystalline structure, with diffraction peaks in excellent agreement with PDF#88-2333. The atomic arrangement of the product structure was further directly observed by atomic-resolution high-angle annular dark-field (HAADF) imaging with atomic number contrast in Fig. 2 b. The corresponding fast Fourier transform (FFT) pattern (inset of Fig. 2 b) features a characteristic fcc structure viewed along the [011] zone axis, with diffraction spots matching the interplanar spacings of the PDF#88-2333 standard, demonstrating the fcc structure of fcc-RuPtIrRhOs. For hcp-RuPtIrRhOs, the distinct peaks observed in the XRD can be effectively correlated with the PDF#06-0663, confirming the hcp phase structure (Fig. 2 c, Supplementary Fig. 2 and Table 2). The atomic-resolution HAADF image further reveals the expected atomic arrangement of the hcp structure (Fig. 2 d), and the corresponding FFT pattern corroborates this assignment with characteristic diffraction features along [0001] zone axis. The EDS (Figs. 2 e and 2 f) mapping results confirm the presence of all intended elements in both fcc- and hcp-RuPtIrRhOs HEA. The FFT radial distributions derived from small-scale HAADF images of multiple nanoparticles (Supplementary Figs. 3 and 4) display peak profiles in close agreement with the XRD patterns in Figs. 2 a (fcc) and 2c (hcp), respectively, thereby substantiating the nanoscale structural uniformity and phase consistency within each sample. The chemical states of the HEAs were affirmed by X-ray photoelectron spectroscopy (XPS) (Supplementary Figs. 5 and 6). The metallic components governing each elemental peak can be identified based on the binding energy values presented in Supplementary Table 3. The results indicate that both the fcc- and hcp- RuPtIrRhOs exist in the metallic state. The atomic ratios of each element in fcc-RuPtIrRhOs and hcp-RuPtIrRhOs were determined from inductively coupled plasma-optical emission spectrometry (ICP-OES) in Supplementary Table 4. The ICP-OES results demonstrate a comparable consistency between fcc- and hcp-RuPtIrRhOs, with nearly identical proportions of constituent elements Mechanism of the regulation of HEA phase structure As illustrated in Fig. 1 , the critical aspect of synthesizing HEAs with diverse phase structures lies in the nucleation structure control. This process requires that one element reacts slightly faster than the others, thereby preventing uniform nucleation of the individual elements. We initiated the modulation based on various influencing factors of the E. For diverse reaction systems, different precursor salts were selected to regulate the E of the target phase precursor, considering the valence state, reducing groups, and types of solvents (see “Methods” for details). This strategy aimed to widen the disparity in E among the precursors, ensuring that the precursor of the target element could be preferentially reduced to form the desired crystallography phase framework. Moreover, precisely modulating the supply manner of precursors narrowed the gap in E among different elements and enabled the continuous uniform co-deposition of multiple metallic components. In this scheme, the intrinsic reaction kinetics of the precursors became negligible. The decisive factors governing the process were instead the precursor concentration and the temporal spacing between successive droplets. Therefore, precise regulation over the reaction rate could be achieved by systematically adjusting both the precursor concentration and the droplet injection rate. We investigated the relative concentration (r.c.) of M x+ remaining in the solution relative to the initial concentration as a function of reaction time to manifest that the reduction rates of the precursor in this strategy were precisely regulated (Figs. 3 a and 3 b). In both systems, all precursors reacted almost completely within 120 s. Due to the lower viscosity of ethylene glycol compared to triethylene glycol, the reduction rates of all elements in the synthesis of hcp-RuPtIrRhOs were relatively faster. For fcc-RuPtIrRhOs, the Pt precursor displayed the most significant downward trend, rapidly decreasing within 10 s, with an average disparity in the relative concentration (∆r.c.) of 79.82% (Supplementary Fig. 7, Tables 5 and 7), while the reduction rates of the other precursors were similar. This indicates that Pt was reduced first to form the nucleus. In contrast, the reduction of Ru in hcp-RuPtIrRhOs was the fastest, achieving an average ∆r.c. of 83.97% within 10 s (Supplementary Fig. 7, Tables 6 and 7), indicating that Ru underwent reduction prior to the other metals during the synthesis of hcp-RuPtIrRhOs. These results offer compelling evidence for the underlying mechanism of the proposed strategy, which postulates that a marginal difference in reduction kinetics between constituent elements can lead to the predominance of specific elements in the HEA phase formation. It is demonstrated that when a particular element exhibits even slightly faster reduction kinetics compared to other components, it may dominate the phase structure evolution in the HEA system. The elemental distribution within a single fcc-RuPtIrRhOs nanoparticle was revealed by STEM-EDS mapping in Fig. 3 c and Supplementary Fig. 8, featuring a concentrated Pt core region surrounded by uniformly dispersed constituent elements without obvious aggregation. For hcp-RuPtIrRhOs, apart from Ru, the constituent elements Pt, Ir, Rh, and Os exhibited a similar dispersion throughout the entire particle with a relatively reduced density in the central core region, thereby leaving the central core Ru-rich (Fig. 3 d and Supplementary Fig. 9). Additionally, the FFT patterns shown in Supplementary Fig. 10, corresponding to the Pt-enriched-core and Ru-enriched-core particles in Figs. 3 c and 3 d respectively, further confirm the presence of fcc and hcp structures, highlighting the structural dependence of HEA growth on the nature of the metal core. HER performances of HEAs with different phase structures HEAs show a wide range of active sites and unique local electronic structures, greatly expanding the design space for catalysts with optimal activity, selectivity, and durability. HER using low-cost, high-purity hydrogen as raw material is a hot spot in energy conversion technology and has attracted increasing attention 41 , 42 . In recent years, numerous studies have highlighted their exceptional activity and durability in the HER 43 – 49 . The electrocatalytic performances of fcc-RuPtIrRhOs and hcp-RuPtIrRhOs toward HER were investigated (Fig. 4 and Supplementary Figs. 11–14), with the commercial Pt/C, Ru/C and Ir/C as references. The HER polarization curves we obtained at a scan rate of 0.01 V s − 2 in an Ar-saturated 1.0 M KOH aqueous solution. The linear sweep voltammogram (LSV) polarization curves of these five catalysts normalized by the electrode area (0.196 cm 2 ) are shown in Fig. 4 a. The HER catalytic activities of both HEAs were higher compared with the commercial Pt/C, Ru/C and Ir/C. Among them, fcc-RuPtIrRhOs possessed exceptional performance, with an overpotential of only 11 mV at a current density of 10 mA cm − 2 . In comparison, the overpotential for hcp-RuPtIrRhOs was 21 mV. The Tafel slopes analyzed to provide more insights into the HER kinetics. As shown in Fig. 4 b, the Tafel slopes of fcc-RuPtIrRhOs, hcp-RuPtIrRhOs, Pt/C, Ru/C and Ir/C were 26.0, 46.8, 51.7, 48.4 and 62.9 mV dec − 1 , respectively. The notably reduced Tafel slope in fcc-RuPtIrRhOs indicates the faster HER kinetics. The accelerated reaction kinetics of both fcc-RuPtIrRhOs and hcp-RuPtIrRhOs were confirmed by electrochemical impedance spectroscopy in Supplementary Fig. 11. The charge transfer resistance of both fcc- and hcp-RuPtIrRhOs was lower than that of Pt/C, Ru/C and Ir/C, with the fcc-RuPtIrRhOs displaying the minimum resistance, indicative of its enhanced charge transfer efficiency relative to the hcp counterpart. The electrochemical active surface areas (ECSA) of the three catalysts were determined from charges associated with underpotentially deposited Cu for further analysis. As depicted in Supplementary Fig. 12, fcc-RuPtIrRhOs with exceptionally high ECSA indicated a greater abundance of active sites and superior mass/transfer compared to hcp-RuPtIrRhOs. Remarkably, fcc-RuPtIrRhOs continued to show superior activity when normalized to ECSA, as indicated by the ECSA-normalized LSV curves (Supplementary Fig. 13). Furthermore, the long-term durability was examined (Figs. 4 c and 4 d). Both fcc-RuPtIrRhOs and hcp-RuPtIrRhOs exhibited remarkable durability after 10000 cycles of repeated catalytic measurements. After the durability test, the dispersion and morphology of the HEAs remained unaltered (Supplementary Fig. 14). Conclusions In conclusion, we successfully realized precise phase regulation in HEAs via accurately modulating the redox potentials of metal precursors, governing the target phase nucleation and concurrent growth of multiple elements subsequently. The reduction rates were precisely engineered by systematically modulating the types of metal salts, chemical environments, and injection methodologies, resulting in a slightly accelerated reduction kinetics for Pt or Ru precursors being observed compared to other constituent elements. The growth of different metallic elements was controlled on the fcc (or hcp) phase Pt (Ru) cores, leading to the formation of HEAs with nearly identical compositions but distinct phase structures. The efficacy and rationality of our crystal phase regulation approach were unequivocally validated through comprehensive characterization by the microscopic elemental distribution and structural analysis and elemental reduction kinetics analysis. The crucial role of crystal phase engineering of HEAs in catalytic applications was highlighted by the observed variations in HER performance among different phase structures of HEAs. The fundamental understanding of HEA crystal phase regulation is advanced, and the exploration of diverse phase-structured HEAs across a wide spectrum of potential applications is facilitated by this strategic approach. Methods Chemical Reagents Potassium (II) tetrachloroplatinate (K 2 PtCl 4 ), Potassium pentachloronitrosylruthenate (II) (K 2 Ru(NO)Cl 5 ), Platinum (II) acetylacetonate (Pt(acac) 2 ), and Osmium (III) chloride (OsCl 3 ) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Ruthenium (III) acetylacetonateIron (Ru(acac) 3 ), and Rhodium(III) 2,4-pentanedionate (Rh(acac) 3 ) were purchased from Anhui Senrise Technology Co., Ltd. Hexachloroiridium (IV) Acid Hydrate (H 2 IrCl 6 ·6H 2 O) was purchased from Shanghai Yien Chemical Technology Co., Ltd. Ethylene glycol (EG), Triethylene glycol (TEG), Commercial iridium 5% on carbon (Commerical Ir/C) and Commercial ruthenium 5% on carbon (Commerical Ru/C) were purchased from Shanghai Macklin Biochemical Co., Ltd. Commercial platinum 20% on carbon (Commerical Pt/C) was purchased from Shanghai Hesen Electric Co., Ltd. Poly(vinylpyrrolidone) (K30) was purchased from Beijing Wokai Biotechnology Co., Ltd. All the materials were utilized without further purification. Synthesis of high-entropy alloy with face-centered cubic phase structure (fcc-RuPtIrRhOs HEA) In a typical synthesis, 20 mL of TEG solution containing PVP (222 mg) was added into a 100-mL three-neck round bottom flask and and subsequently preheated at 230 o C in a heating mantle under magnetic stirring for 10 min. Then, 5 mL of TEG solution containing Ru(acac) 3 (23.9 mg), K 2 PtCl 4 (4.5 mg), H 2 IrCl 6 ·H 2 O (5.1 µL), Rh(acac) 3 (4.5 mg), and OsCl 3 (3.5 mg) was introduced dropwise into the reaction solution by a syringe pump at a specific rate of 0.1 mL/min after 20 min of ultrasonic treatment. The reaction was maintained at 230 ℃ under magnetic stirring for 2 h. After the reaction, the reaction mixture was quenched in an ice water bath and the fcc-RuPtIrRhOs HEA was collected by precipitation with a great amount of acetone and washed two times with a mixture of ethanol and acetone (1:3 v/v). Synthesis of high-entropy alloy with hexagonal close-packed phase structure (hcp-RuPtIrRhOs HEA) In a typical synthesis, 20 mL of EG solution containing PVP (222 mg) was added into a 100-mL three-neck round bottom flask and and subsequently preheated at 200 in a heating mantle under magnetic stirring for 10 min. Then, 5 mL of EG solution containing K 2 Ru(NO)Cl 5 (23.2 mg), Pt(acac) 2 (4.3 mg), H 2 IrCl 6 ·H 2 O (5.1 µL), Rh(acac) 3 (4.5 mg), and OsCl 3 (3.5 mg) was introduced dropwise into the reaction solution by a syringe pump at a specific rate of 1 mL/min after 20 min of ultrasonic treatment. The reaction was maintained at 200 o C under magnetic stirring for 2 h. After the reaction, the reaction mixture was quenched in an ice water bath and the hcp-RuPtIrRhOs HEA was collected by precipitation with a great amount of acetone and washed two times with a mixture of ethanol and acetone (1:3 v/v). Characterizations The scanning transmission electron microscopy (STEM) imaging and energy-dispersive X-ray spectroscopy (EDS) mapping were acquired on JEOL JEM-ARM200CF and JEM-ARM300F2 electron microscope operated at 200 kV. The transmission electron microscopy (TEM) images were collected by JEM-F200 electron microscope, operating at 200 kV. The X-ray diffraction (XRD) characterizations were performed on SmartLab 9 kW diffractometer equipped with Cu-Kα radiation. X-ray photoelectron spectroscopy (XPS) measurements were conducted on a Thermo Scientific, ESCALAB 250Xi system. The inductively coupled plasma-optical emission spectrometry (ICP-OES) measurements were collected on Agilent 5110. Electrochemical Measurements All electrochemical measurements were performed on a CHI 760 with a conventional three-electrode system, where glassy carbon, Hg/HgO, and graphite rod were utilized as the working electrode, reference electrode, and counter electrode, respectively. In a standard procedure for the preparation of catalyst samples, 1 mg of the HEA and 4 mg of carbon support (Vulcan XC-72R) were dispersed in a 1-mL mixed solution of isopropanol (710 µL), water (250 µL), and Nafion solution (40 µL, Sigma Aldrich 5 wt%). The catalyst was ultrasonic treated for at least 2 h. 10 µL of the catalyst ink were added to a polished glassy carbon rotating disk electrode in two aliquots with a geometric surface of 0.196 cm 2 and dried in the air at room temperature. In a typical electrocatalytic hydrogen evolution reaction (HER) measurement, the electrode was subjected to 50 cycles of cyclic voltammetry (CV) in Ar-saturated 1 M KOH with a high scan rate of 0.5 V/s to obtain a stable surface. The obtained potentials for all LSV curves were referenced to the reversible hydrogen electrode (RHE) and all polarization curves were presented with iR compensation. The linear sweep voltammetry (LSV) was conducted from − 0.90 to − 1.2 V (versus Hg/HgO) at a scan rate of 0.01 V/s and a rotating speed of 1600 rpm/s to evaluate the HER performance. For the long-term stability test, we carried out 10,000 cycles of CV in the same region as LSV for HER at 0.1 V/s. The corresponding Tafel plots were obtained by fitting the linear portion of the curve into the Tafel equation η = b log (j) + a, in which b is the Tafel plot. The electrochemical active surface areas (ECSAs) of the three catalysts were further determined using Cu underpotential deposition (Cu upd ) for analysis of catalytic performance. Briefly, the electrode was first cycled in Ar-saturated 0.5 M H 2 SO 4 from 0.01 to 1.1 V RHE at a scan rate of 10 mV s − 1 after cleaning the electrode at 500 mV s − 1 for several hundred cycles. Then, the potential was fixed at 0.3 V RHE for 100 s in an Ar-saturated aqueous electrolyte containing 0.5 M H 2 SO 4 and 5 mM CuSO 4 followed by a linear scan from 0.3 to 1.1 V RHE to collect the Cu upd curve. The ECSAs were calculated by integrating the stripping charge of Cu upd and subtracting the charge obtained under the same conditions in 0.5 M H 2 SO 4 , assuming a charge density of 420 µC. The ECSA can be calibrated as: $$\:ECSA=\frac{{Q}_{Cu}}{{m}_{metal}\times\:420\:\mu\:C\:{cm}^{-2}}$$ where m metal is the mass loading of the noble metal on a certain geometric area of the working electrode and 420 µC cm − 2 is the value of charge consumed for the formation of a Cu upd monolayer on active metal sites. Declarations Competing interests The authors declare no competing interests. Author contributions Y.L.Z. conceived the research concept. L.F., M.Q.Z., and W. Z. supervised the research. Y.L.Z. carried out the main experiments, collected and analyzed the data. X.J.P. performed transmission electron microscopy characterizations, collected and analyzed the data. L.F., M.Q.Z., W. Z., Y.L.Z., and X.J.P. cowrote the manuscript. All the authors contributed to data analysis and scientific discussion. Acknowledgements The research was supported by the Natural Science Foundation of China (Grants 22025303), the CAS Project for Young Scientists in Basic Research (YSBR-003), and the Fundamental Research Funds for the Central Universities. We would like to acknowledge the Center for Electron Microscopy at Wuhan University for their substantial support to TEM characterization. We also thank the Electron Microscopy Center at the University of Chinese Academy of Sciences for the STEM work. We also thank the Core Facility of Wuhan University for providing the ICP-OES and XPS tests, and the Core Research Facilities of the College of Chemistry and Molecular Sciences at Wuhan University for the XRD characterization. We also thank the Institute for Advanced Studies of Wuhan University for their assistance in TEM characterization. Data availability The data that support the findings of this study are available from the corresponding authors on reasonable request. References Li M et al (2024) High-entropy alloy electrocatalysts go to (sub-)nanoscale. Sci Adv 10:eadn2877 Ding Z et al (2025) The integral role of high-entropy alloys in advancing solid-state hydrogen storage. Interdiscip Mater 4:75–108 An Z et al (2024) Negative mixing enthalpy solid solutions deliver high strength and ductility. Nature 625, 697 – 702 Liang J et al (2024) High-entropy alloy array via liquid metal nanoreactor. Adv Mater 36:2403865 Jung S-G et al (2022) High critical current density and high-tolerance superconductivity in high-entropy alloy thin films. Nat Commun 13:3373 Liang J, Cao G, Zeng M, Fu L (2024) Controllable synthesis of high-entropy alloys. Chem Soc Rev 53:6021–6041 Yao Y et al (2022) High-entropy nanoparticles: Synthesis-structure-property relationships and data-driven discovery. Science 376:eabn3103 Li L et al (2022) Phase engineering of a ruthenium nanostructure toward high-performance bifunctional hydrogen catalysis. ACS Nano 16:14885–14894 Tan X et al (2020) Closest packing polymorphism interfaced metastable transition metal for efficient hydrogen evolution. Adv Mater 32:2002857 Li Q et al (2015) New approach to fully ordered fct-FePt nanoparticles for much enhanced electrocatalysis in acid. Nano Lett 15:2468–2473 Fan Z et al (2015) Stabilization of 4H hexagonal phase in gold nanoribbons. Nat Commun 6:7684 Nguyen YN et al (2025) Facile synthesis of rhodium-based nanocrystals in a metastable phase and evaluation of their thermal and catalytic properties. Small Methods 9:2401143 Zhang J et al (2023) Kinetic-modulated crystal phase of Ru for hydrogen oxidation. Small 19:2207038 Yun Q et al (2019) Synthesis of PdM (M = Zn, Cd, ZnCd) nanosheets with an unconventional face-centered tetragonal phase as highly efficient electrocatalysts for ethanol oxidation. ACS Nano 13:14329–14336 Wang X et al (2024) Facet-controlled synthesis of unconventional-phase metal alloys for highly efficient hydrogen oxidation. J Am Chem Soc 146:24141–24149 Yao Q, Yu Z, Li L, Huang X (2023) Strain and surface engineering of multicomponent metallic nanomaterials with unconventional phases. Chem Rev 123:9676–9717 Yun Q et al (2023) Recent progress on phase engineering of nanomaterials. Chem. Rev. 123, 13489 – 13692 Cui M et al (2022) Multi-principal elemental intermetallic nanoparticles synthesized via a disorder-to-order transition. Sci Adv 8:eabm4322 Nakamura M et al (2023) B2-structured indium-platinum group metal high-entropy intermetallic nanoparticles. Chem Commun 59:9485–9488 Liu J, Zhang Y, Ding Y, Zeng M, Fu L (2024) Atomic design of high-entropy alloys for electrocatalysis. ACS Mater Lett 6:2642–2659 Li H, Lai J, Li Z, Wang L (2021) Multi-sites electrocatalysis in high-entropy alloys. Adv Funct Mater 31:2106715 Löffler T, Ludwig A, Rossmeisl J, Schuhmann W (2021) What makes high-entropy alloys exceptional electrocatalysts? Angew Chem Int Ed 60:26894 Yao Y et al (2018) Carbothermal shock synthesis of high-entropy-alloy nanoparticles. Science 359, 1489 – 1494 Zhao J-Z, Ahmed T, Jiang H-X, He J, Sun Q (2017) Solidification of immiscible alloys: A review. Acta Metall Sin (Engl Lett 30:1–28 Chen P-C et al (2019) Interface and heterostructure design in polyelemental nanoparticles. Science 363, 959 – 964 Liu H et al (2024) Unveiling atomic-scaled local chemical order of high-entropy intermetallic catalyst for alkyl-substitution-dependent alkyne semihydrogenation. J Am Chem Soc 146:20193–20204 Li Y et al (2023) Laser annealing-induced phase transformation behaviors of high entropy metal alloy, oxide, and nitride nanoparticle combinations. Adv Funct Mater 33:2211279 Yang Y et al (2021) Determining the three-dimensional atomic structure of an amorphous solid. Nature 592, 60 – 64 Zhang Q et al (2022) Crystal structure control of binary and ternary solid-solution alloy nanoparticles with a face-centered cubic or hexagonal close-packed phase. J Am Chem Soc 144:4224–4232 Zhang Q et al (2018) Selective Control of Fcc and Hcp Crystal Structures in Au–Ru Solid-Solution Alloy Nanoparticles. Nat Commun 9:510 LaMer VK, Dinegar RH (1950) Theory, production and mechanism of formation of monodispersed hydrosols. J Am Chem Soc 72:4847–4854 Zhou M et al (2016) Quantitative analysis of the reduction kinetics responsible for the one-pot synthesis of Pd–Pt bimetallic nanocrystals with different structures. J Am Chem Soc 138:12263–12270 Kar N et al (2024) Retrosynthetic design of core–shell nanoparticles for thermal conversion to monodisperse high-entropy alloy nanoparticles. Nat Synth 3:175–184 Lao X et al (2023) Pd-enriched-core/Pt-enriched-shell high-entropy alloy with face-centred cubic structure for C1 and C2 alcohol oxidation. Angew Chem Int Ed 62:e202304510 Wang C et al (2023) Facet-controlled synthesis of platinum-group-metal quaternary alloys: The case of nanocubes and {100} facets. J Am Chem Soc 145:2553–2560 Nguyen QN et al (2024) Elucidating the role of reduction kinetics in the phase-controlled growth on preformed nanocrystal seeds: A case study of Ru. J Am Chem Soc 146:12040–12052 Huang X et al (2024) Regioselective epitaxial growth of metallic heterostructures. Nat Nanotechnol 19:1306–1315 Gao W et al (2019) Probing the dynamics of nanoparticle formation from a precursor at atomic resolution. Sci Adv 5:eaau9590 Wang C, He J, Xia Y (2024) Controlling the composition and elemental distribution of bi- and multi-metallic nanocrystals via dropwise addition. Nat Synth 3:1076–1082 Liu Y-H et al (2023) Toward controllable and predictable synthesis of high-entropy alloy nanocrystals. Sci Adv 9:eadf9931 Sun Y et al (2021) Modulating electronic structure of metal-organic frameworks by introducing atomically dispersed Ru for efficient hydrogen evolution. Nat Commun 12:1369 Yang J et al (2023) Ir nanoparticles anchored on metal-organic frameworks for efficient overall water splitting under pH-universal conditions. Angew Chem Int Ed 62:e202302220 Wang Q et al (2025) Size-controllable high-entropy alloys toward stable hydrogen production at industrial-scale current densities. Adv Mater 37:2420173 Mao Q et al (2023) Multisite synergism-induced electron regulation of high-entropy alloy metallene for boosting alkaline hydrogen evolution reaction. Adv Funct Mater 33:2304963 Kang Y et al (2023) Mesoporous multimetallic nanospheres with exposed highly entropic alloy sites. Nat Commun 14:4182 Cui X et al (2024) Rapid high-temperature liquid shock synthesis of high-entropy alloys for hydrogen evolution reaction. ACS Nano 18:2948–2957 Feng G et al (2021) Sub-2 nm ultrasmall high-entropy alloy nanoparticles for extremely superior electrocatalytic hydrogen evolution. J Am Chem Soc 143:17117–17127 Wang C et al (2024) Octahedral nanocrystals of Ru-doped PtFeNiCuW/CNTs high-entropy alloy: High performance toward pH-universal hydrogen evolution reaction. Adv Mater 36:2400433 Mahin J et al (2025) All iron-group and platinum-group elements metal high-entropy alloy nanoparticles. Angew Chem Int Ed 64:e202502552 Additional Declarations There is NO Competing Interest. Supplementary Files supplementaryinformation.docx supplementary information Cite Share Download PDF Status: Posted 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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Fu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuUlEQVRIiWNgGAWjYBACPgbGhg8MFQwJII4EUVrYGBgbZzCcIU0LA+MMxjaStLA3NzbzzjucZ3CA+eBtHga7PMJaeA4CtWw7XGxwgC3ZmochuZiwFonE9se8224nbjjAYybNw3AgsYGgFvmHQFvmgLTwfyNSiwQjUEsD2BY2IrXwJDY2zjn2P3HmYTZjyzkGyYS18LMff9jwpiYtse9488MbbyrsCGtBAGYQYUC8+lEwCkbBKBgFeAAAucI7/GYsPfEAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0003-1356-4422","institution":"Wuhan University","correspondingAuthor":true,"prefix":"","firstName":"Lei","middleName":"","lastName":"Fu","suffix":""},{"id":563172003,"identity":"7cb3f194-a75f-46c4-906d-0af35b63dda1","order_by":1,"name":"Yile Zhang","email":"","orcid":"","institution":"Wuhan University","correspondingAuthor":false,"prefix":"","firstName":"Yile","middleName":"","lastName":"Zhang","suffix":""},{"id":563172004,"identity":"1b4bd399-c79e-43fc-86b6-fb35e0f538f0","order_by":2,"name":"Xingjie Peng","email":"","orcid":"","institution":"University of Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Xingjie","middleName":"","lastName":"Peng","suffix":""},{"id":563172005,"identity":"0f16deea-08a7-495b-8de9-4dcdf40dc324","order_by":3,"name":"Ziyue Zeng","email":"","orcid":"","institution":"Wuhan University","correspondingAuthor":false,"prefix":"","firstName":"Ziyue","middleName":"","lastName":"Zeng","suffix":""},{"id":563172006,"identity":"01e69a4c-ba28-4cd9-8679-0cf5df5aece5","order_by":4,"name":"Wu Zhou","email":"","orcid":"https://orcid.org/0000-0002-6803-1095","institution":"University of Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Wu","middleName":"","lastName":"Zhou","suffix":""},{"id":563172007,"identity":"c4ea06ac-4add-427c-8367-2663d59eb7e6","order_by":5,"name":"Mengqi Zeng","email":"","orcid":"https://orcid.org/0000-0002-1442-052X","institution":"Wuhan University","correspondingAuthor":false,"prefix":"","firstName":"Mengqi","middleName":"","lastName":"Zeng","suffix":""}],"badges":[],"createdAt":"2025-12-08 13:45:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8308350/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8308350/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":99308606,"identity":"94dd86fc-77ea-49db-aa84-1cc34b7f756d","added_by":"auto","created_at":"2025-12-31 16:08:49","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":941073,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.docx","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/6e16eb1917292cf95c791b5c.docx"},{"id":99308475,"identity":"6b9064da-8a70-4af4-9a95-d90961806c13","added_by":"auto","created_at":"2025-12-31 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16:08:43","extension":"jpeg","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":145298,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/c90a62b04c629eebdf50a36f.jpeg"},{"id":98852949,"identity":"e6d718ba-f9e5-44ae-9ad8-d9858bec4896","added_by":"auto","created_at":"2025-12-23 06:58:09","extension":"png","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":141732,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/f4fb35272cf33bbf79ebba55.png"},{"id":98852952,"identity":"f716ce71-7184-45e5-9c7f-abce0c8a6d70","added_by":"auto","created_at":"2025-12-23 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16:08:23","extension":"png","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":62567,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/016088296252814001240429.png"},{"id":98852954,"identity":"7457bb00-ee4c-47d2-8252-eaef90bbbef8","added_by":"auto","created_at":"2025-12-23 06:58:09","extension":"xml","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":88739,"visible":true,"origin":"","legend":"","description":"","filename":"NCOMMS250993910structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/45038ad460d4af534eb8df80.xml"},{"id":98852953,"identity":"700f1683-ac03-4915-b31a-f5d1ea008b0e","added_by":"auto","created_at":"2025-12-23 06:58:09","extension":"html","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":97559,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/8b5f66b1c8d10715096a168f.html"},{"id":98852936,"identity":"9df6150c-0517-4463-9ad4-9dfc1b29f2cc","added_by":"auto","created_at":"2025-12-23 06:58:08","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":286289,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic diagram of fcc-RuPtIrRhOs and hcp-RuPtIrRhOs synthesis.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/79624680493d59df4fb89dd4.png"},{"id":98852937,"identity":"e151281e-b26e-456a-a949-2166d8200de9","added_by":"auto","created_at":"2025-12-23 06:58:08","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":757452,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStructural and elemental characterization of fcc-RuPtIrRhOs and hcp-RuPtIrRhOs. \u003c/strong\u003e(a) XRD profile of fcc-RuPtIrRhOs. (b) Atomic-resolution HAADF-STEM image of a fcc-RuPtIrRhOs nanoparticle. Inset shows the corresponding FFT pattern (scale bar: 5 1/nm). (c) XRD profile of hcp-RuPtIrRhOs. (d) Atomic-resolution HAADF-STEM image of a hcp-RuPtIrRhOs nanoparticle. Inset shows the corresponding FFT pattern (scale bar: 5 1/nm). (e) STEM-EDS elemental maps of fcc-RuPtIrRhOs. (f) STEM-EDS elemental maps of hcp-RuPtIrRhOs.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/de54854c53fea2e16db10d80.png"},{"id":98852941,"identity":"1d9b5301-cfc8-48db-bb84-a9eb4b6e471c","added_by":"auto","created_at":"2025-12-23 06:58:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":482630,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe mechanism of the regulation of HEA phase structure.\u003c/strong\u003e (a, b) The relationship between the relative concentration (r.c.) of M\u003csup\u003ex+\u003c/sup\u003e remaining in the reaction solutions of (a), fcc-RuPtIrRhOs and (b), hcp-RuPtIrRhOs relative to the initial concentration versus reaction time. (c, d) Atomic-resolution HAADF-STEM images and STEM-EDS elemental maps of (c) a fcc-RuPtIrRhOs nanoparticle and (d) a hcp-RuPtIrRhOs nanoparticle.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/25165241c4810c1db49fe8cc.png"},{"id":98852944,"identity":"6d59af2d-ca96-4947-aab3-7b7d172aeca4","added_by":"auto","created_at":"2025-12-23 06:58:09","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":294707,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eElectrocatalytic activity and durability for HER in 1.0 M KOH.\u003c/strong\u003e (a) Polarization curves of fcc-RuPtIrRhOs, hcp-RuPtIrRhOs, Pt/C, Ru/C and Ir/C. (b) Corresponding Tafel plots.(c, d) HER polarization curves of fcc-RuPtIrRhOs and hcp-RuPtIrRhOs before and after 10000 cycles in 1.0 M KOH, respectively.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/23294d11c6210205bca56c4c.png"},{"id":108448665,"identity":"629f4a3e-a9cd-49ec-ace8-1183523e4096","added_by":"auto","created_at":"2026-05-04 18:41:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1889298,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/efd700ef-e213-4d15-bebc-d3462095a046.pdf"},{"id":99308483,"identity":"a1420c6d-f669-4a3b-aaf0-3bccd2393155","added_by":"auto","created_at":"2025-12-31 16:08:39","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1356695,"visible":true,"origin":"","legend":"supplementary information","description":"","filename":"supplementaryinformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-8308350/v1/e0403ca11f457285c1d738f2.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Tailoring Crystal Phase of High-Entropy Alloy Nanoparticles via Redox-Mediated Engineering","fulltext":[{"header":"Introduction","content":"\u003cp\u003eHigh-entropy alloys (HEAs) provide an enticing material platform for different applications, achieving remarkable results in various fields such as catalysis\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e, energy storage and conversion\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e, mechanics\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e, and so on\u003csup\u003e4,5\u003c/sup\u003e. The compositional flexibility and complexity of atomic configuration of HEAs exhibits unique potential and appeal in the field of catalysis\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. Phase engineering of nanomaterials represents a powerful strategy to precisely modulate their physicochemical properties and optimize functional performance\u003csup\u003e\u003cspan additionalcitationids=\"CR9 CR10\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. Particularly, the construction of metallic nanomaterials with unconventional phases distinct from the thermodynamically stable phases has emerged as an alluring approach to developing highly efficient catalysts\u003csup\u003e\u003cspan additionalcitationids=\"CR13 CR14 CR15 CR16\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Therefore, the modulation of the phase structure of HEAs is highly charming, the abundant phase combinations derived from the components and crystal structure offer further opportunities for adjusting their properties to attain the desired applications\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Moreover, the phase engineering of HEAs has garnered significant attention yet remains incompletely explored\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eA fundamental challenge in HEA phase engineering lies in achieving high configurational entropy while maintaining precise control over atomic configurations. On the one hand, considering the differences in atomic radius, electronegativity, and the mixing enthalpy among elements\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e, phase separation is inclined to take place under near-equilibrium conditions\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e, claiming synthesis of HEAs in a highly controllable manner is difficult. On the other hand, the extensively investigated approaches of overcoming the immiscibility of elements via high-energy reactions and quenching can readily attain the high-entropy state\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e. However, precise atomic positioning cannot be achieved due to the poorly controlled kinetic process resulting from the rapid and intense energy injection. Consequently, there are grand challenges to realizing the phase regulation of HEAs.\u003c/p\u003e \u003cp\u003eHerein, we accomplished the phase control of HEAs by the modulation kinetic engineering of the redox potentials of the metal precursors, including the design of the target phase nucleation and the subsequent co-reduction growth of multiple elements. HEAs with face-centered cubic (fcc) and hexagonal close-packed (hcp) phase structures under the same composition and proportion were obtained, realizing the crystal phase control of HEAs. Energy-dispersive X-ray spectroscopy (EDS) analysis and the qualitative analysis of the reduction rate of diverse metal precursors disclosed the reaction mechanism. Moreover, we systematically probed into the impact of the crystal structure of HEAs on the catalytic performance via the electrocatalytic hydrogen evolution reaction (HER). In alkaline conditions, at a current density of 10 mA/cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, the overpotential of the fcc phase HEA and the hcp phase HEA was 11 mV and 21 mV respectively. This signified that they manifested excellent yet distinct catalytic activities, uncovering the profound significance of HEA phase engineering for catalysis. The crucial part played by atomic-scale structure control was forcefully demonstrated in HEAs.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eThe strategy for regulating of phase structures HEAs\u003c/h2\u003e \u003cp\u003eAccording to the classical nucleation theory, heterogeneous nucleation possesses a lower energy barrier, facilitating precise manipulation of the growth mode. Furthermore, the crystal structure of an alloy can be determined by that of its nucleus\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. This implies that the structure of the core can be modulated through precise control of the reduction kinetics of the metal precursor, thereby enabling the construction of alloys with diverse phase structures. The reduction reaction of metal ions (M\u003csup\u003en+\u003c/sup\u003e) can be described by the following:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:{M}^{n+}+n{e}^{-}=M$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe Nernst equation for the reaction in the formula is shown as\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\:{E}_{{M}^{n+}/M}={E}_{{M}^{n+}/M}^{\\theta\\:}+\\frac{RT}{nF}\\text{l}\\text{n}\\left[{M}^{n+}\\right]$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere E, E\u003csup\u003eθ\u003c/sup\u003e, R, T, n, and F are, respectively, the redox potential, the standard reduction potentials, the gas constant, temperature, the mole number of electrons, and the Faraday constant. E generally controls the morphology and composition of metals or alloys by governing reduction kinetics\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. The E\u003csup\u003eθ\u003c/sup\u003e of metal ions determines their reduction feasibility and rates, thus regulating the transformation efficiency from ionic to metallic states\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. It is worth noting that the E of metal ions also depends critically on concentration, temperature, and the number of transferred electrons. These parameters not only modulate the thermodynamic driving force but also provide a lever for controlling reduction kinetics. For instance, the reduction rates of metal elements can be influenced by factors such as their valence state, surrounding groups, and the chemical environment, among others\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e,\u003cspan additionalcitationids=\"CR37\" citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. By altering these conditions, the relative reduction rates between elements can be modified. In addition, the disparity in the intrinsic reduction rate of metal ions could be surmounted through regularly introducing metal precursors\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e,\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. By continuously supplying additional precursors to compensate for consumption, maintaining a steady-state equilibrium of precursor availability.\u003c/p\u003e \u003cp\u003eThrough precise fine-tuning of precursor reduction potentials to control reduction kinetics, we first intentionally amplified the kinetic disparity to direct crystal phase formation, and subsequently attenuated the difference to facilitate concurrent reduction of multi-metal precursors, ultimately yielding high-entropy state products. In a typical synthesis, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the Pt and Ru precursors exhibited higher E compared to other metal precursors, driving the formation of their characteristic phase structures. The maintenance of continuous and stable precursor supply made certain uniform reduction rates across all metal elements, realizing the multiple metal precursors co-reduction, and ultimately obtaining HEAs with fcc and hcp phase structures (fcc-RuPtIrRhOs and hcp-RuPtIrRhOs).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eThe Characterization of HEA with different phase structure\u003c/h3\u003e\n\u003cp\u003eTo investigate the crystal structure of the two synthesized HEAs, X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) analyses were conducted (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, Supplementary Fig.\u0026nbsp;1 and Table\u0026nbsp;1 reveal that fcc-RuPtIrRhOs exhibited the typical fcc crystalline structure, with diffraction peaks in excellent agreement with PDF#88-2333. The atomic arrangement of the product structure was further directly observed by atomic-resolution high-angle annular dark-field (HAADF) imaging with atomic number contrast in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb. The corresponding fast Fourier transform (FFT) pattern (inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb) features a characteristic fcc structure viewed along the [011] zone axis, with diffraction spots matching the interplanar spacings of the PDF#88-2333 standard, demonstrating the fcc structure of fcc-RuPtIrRhOs. For hcp-RuPtIrRhOs, the distinct peaks observed in the XRD can be effectively correlated with the PDF#06-0663, confirming the hcp phase structure (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, Supplementary Fig.\u0026nbsp;2 and Table\u0026nbsp;2). The atomic-resolution HAADF image further reveals the expected atomic arrangement of the hcp structure (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed), and the corresponding FFT pattern corroborates this assignment with characteristic diffraction features along [0001] zone axis. The EDS (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef) mapping results confirm the presence of all intended elements in both fcc- and hcp-RuPtIrRhOs HEA. The FFT radial distributions derived from small-scale HAADF images of multiple nanoparticles (Supplementary Figs.\u0026nbsp;3 and 4) display peak profiles in close agreement with the XRD patterns in Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea (fcc) and 2c (hcp), respectively, thereby substantiating the nanoscale structural uniformity and phase consistency within each sample. The chemical states of the HEAs were affirmed by X-ray photoelectron spectroscopy (XPS) (Supplementary Figs.\u0026nbsp;5 and 6). The metallic components governing each elemental peak can be identified based on the binding energy values presented in Supplementary Table\u0026nbsp;3. The results indicate that both the fcc- and hcp- RuPtIrRhOs exist in the metallic state. The atomic ratios of each element in fcc-RuPtIrRhOs and hcp-RuPtIrRhOs were determined from inductively coupled plasma-optical emission spectrometry (ICP-OES) in Supplementary Table\u0026nbsp;4. The ICP-OES results demonstrate a comparable consistency between fcc- and hcp-RuPtIrRhOs, with nearly identical proportions of constituent elements\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eMechanism of the regulation of HEA phase structure\u003c/h3\u003e\n\u003cp\u003eAs illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the critical aspect of synthesizing HEAs with diverse phase structures lies in the nucleation structure control. This process requires that one element reacts slightly faster than the others, thereby preventing uniform nucleation of the individual elements. We initiated the modulation based on various influencing factors of the E. For diverse reaction systems, different precursor salts were selected to regulate the E of the target phase precursor, considering the valence state, reducing groups, and types of solvents (see \u0026ldquo;Methods\u0026rdquo; for details). This strategy aimed to widen the disparity in E among the precursors, ensuring that the precursor of the target element could be preferentially reduced to form the desired crystallography phase framework. Moreover, precisely modulating the supply manner of precursors narrowed the gap in E among different elements and enabled the continuous uniform co-deposition of multiple metallic components. In this scheme, the intrinsic reaction kinetics of the precursors became negligible. The decisive factors governing the process were instead the precursor concentration and the temporal spacing between successive droplets. Therefore, precise regulation over the reaction rate could be achieved by systematically adjusting both the precursor concentration and the droplet injection rate.\u003c/p\u003e \u003cp\u003eWe investigated the relative concentration (r.c.) of M\u003csup\u003ex+\u003c/sup\u003e remaining in the solution relative to the initial concentration as a function of reaction time to manifest that the reduction rates of the precursor in this strategy were precisely regulated (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). In both systems, all precursors reacted almost completely within 120 s. Due to the lower viscosity of ethylene glycol compared to triethylene glycol, the reduction rates of all elements in the synthesis of hcp-RuPtIrRhOs were relatively faster. For fcc-RuPtIrRhOs, the Pt precursor displayed the most significant downward trend, rapidly decreasing within 10 s, with an average disparity in the relative concentration (∆r.c.) of 79.82% (Supplementary Fig.\u0026nbsp;7, Tables\u0026nbsp;5 and 7), while the reduction rates of the other precursors were similar. This indicates that Pt was reduced first to form the nucleus. In contrast, the reduction of Ru in hcp-RuPtIrRhOs was the fastest, achieving an average ∆r.c. of 83.97% within 10 s (Supplementary Fig.\u0026nbsp;7, Tables\u0026nbsp;6 and 7), indicating that Ru underwent reduction prior to the other metals during the synthesis of hcp-RuPtIrRhOs. These results offer compelling evidence for the underlying mechanism of the proposed strategy, which postulates that a marginal difference in reduction kinetics between constituent elements can lead to the predominance of specific elements in the HEA phase formation. It is demonstrated that when a particular element exhibits even slightly faster reduction kinetics compared to other components, it may dominate the phase structure evolution in the HEA system.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe elemental distribution within a single fcc-RuPtIrRhOs nanoparticle was revealed by STEM-EDS mapping in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec and Supplementary Fig.\u0026nbsp;8, featuring a concentrated Pt core region surrounded by uniformly dispersed constituent elements without obvious aggregation. For hcp-RuPtIrRhOs, apart from Ru, the constituent elements Pt, Ir, Rh, and Os exhibited a similar dispersion throughout the entire particle with a relatively reduced density in the central core region, thereby leaving the central core Ru-rich (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed and Supplementary Fig.\u0026nbsp;9). Additionally, the FFT patterns shown in Supplementary Fig.\u0026nbsp;10, corresponding to the Pt-enriched-core and Ru-enriched-core particles in Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed respectively, further confirm the presence of fcc and hcp structures, highlighting the structural dependence of HEA growth on the nature of the metal core.\u003c/p\u003e\n\u003ch3\u003eHER performances of HEAs with different phase structures\u003c/h3\u003e\n\u003cp\u003eHEAs show a wide range of active sites and unique local electronic structures, greatly expanding the design space for catalysts with optimal activity, selectivity, and durability. HER using low-cost, high-purity hydrogen as raw material is a hot spot in energy conversion technology and has attracted increasing attention\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e,\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e. In recent years, numerous studies have highlighted their exceptional activity and durability in the HER\u003csup\u003e\u003cspan additionalcitationids=\"CR44 CR45 CR46 CR47 CR48\" citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e. The electrocatalytic performances of fcc-RuPtIrRhOs and hcp-RuPtIrRhOs toward HER were investigated (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and Supplementary Figs.\u0026nbsp;11\u0026ndash;14), with the commercial Pt/C, Ru/C and Ir/C as references. The HER polarization curves we obtained at a scan rate of 0.01 V s\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e in an Ar-saturated 1.0 M KOH aqueous solution. The linear sweep voltammogram (LSV) polarization curves of these five catalysts normalized by the electrode area (0.196 cm\u003csup\u003e2\u003c/sup\u003e) are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea. The HER catalytic activities of both HEAs were higher compared with the commercial Pt/C, Ru/C and Ir/C. Among them, fcc-RuPtIrRhOs possessed exceptional performance, with an overpotential of only 11 mV at a current density of 10 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. In comparison, the overpotential for hcp-RuPtIrRhOs was 21 mV. The Tafel slopes analyzed to provide more insights into the HER kinetics. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, the Tafel slopes of fcc-RuPtIrRhOs, hcp-RuPtIrRhOs, Pt/C, Ru/C and Ir/C were 26.0, 46.8, 51.7, 48.4 and 62.9 mV dec\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. The notably reduced Tafel slope in fcc-RuPtIrRhOs indicates the faster HER kinetics. The accelerated reaction kinetics of both fcc-RuPtIrRhOs and hcp-RuPtIrRhOs were confirmed by electrochemical impedance spectroscopy in Supplementary Fig.\u0026nbsp;11. The charge transfer resistance of both fcc- and hcp-RuPtIrRhOs was lower than that of Pt/C, Ru/C and Ir/C, with the fcc-RuPtIrRhOs displaying the minimum resistance, indicative of its enhanced charge transfer efficiency relative to the hcp counterpart. The electrochemical active surface areas (ECSA) of the three catalysts were determined from charges associated with underpotentially deposited Cu for further analysis. As depicted in Supplementary Fig.\u0026nbsp;12, fcc-RuPtIrRhOs with exceptionally high ECSA indicated a greater abundance of active sites and superior mass/transfer compared to hcp-RuPtIrRhOs. Remarkably, fcc-RuPtIrRhOs continued to show superior activity when normalized to ECSA, as indicated by the ECSA-normalized LSV curves (Supplementary Fig.\u0026nbsp;13). Furthermore, the long-term durability was examined (Figs.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed). Both fcc-RuPtIrRhOs and hcp-RuPtIrRhOs exhibited remarkable durability after 10000 cycles of repeated catalytic measurements. After the durability test, the dispersion and morphology of the HEAs remained unaltered (Supplementary Fig.\u0026nbsp;14).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn conclusion, we successfully realized precise phase regulation in HEAs via accurately modulating the redox potentials of metal precursors, governing the target phase nucleation and concurrent growth of multiple elements subsequently. The reduction rates were precisely engineered by systematically modulating the types of metal salts, chemical environments, and injection methodologies, resulting in a slightly accelerated reduction kinetics for Pt or Ru precursors being observed compared to other constituent elements. The growth of different metallic elements was controlled on the fcc (or hcp) phase Pt (Ru) cores, leading to the formation of HEAs with nearly identical compositions but distinct phase structures. The efficacy and rationality of our crystal phase regulation approach were unequivocally validated through comprehensive characterization by the microscopic elemental distribution and structural analysis and elemental reduction kinetics analysis. The crucial role of crystal phase engineering of HEAs in catalytic applications was highlighted by the observed variations in HER performance among different phase structures of HEAs. The fundamental understanding of HEA crystal phase regulation is advanced, and the exploration of diverse phase-structured HEAs across a wide spectrum of potential applications is facilitated by this strategic approach.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003c/div\u003e \u003c/div\u003e\n\n "},{"header":"Methods","content":"\u003ch2\u003eChemical Reagents\u003c/h2\u003e\u003cp\u003ePotassium (II) tetrachloroplatinate (K\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e4\u003c/sub\u003e), Potassium pentachloronitrosylruthenate (II) (K\u003csub\u003e2\u003c/sub\u003eRu(NO)Cl\u003csub\u003e5\u003c/sub\u003e), Platinum (II) acetylacetonate (Pt(acac)\u003csub\u003e2\u003c/sub\u003e), and Osmium (III) chloride (OsCl\u003csub\u003e3\u003c/sub\u003e) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Ruthenium (III) acetylacetonateIron (Ru(acac)\u003csub\u003e3\u003c/sub\u003e), and Rhodium(III) 2,4-pentanedionate (Rh(acac)\u003csub\u003e3\u003c/sub\u003e) were purchased from Anhui Senrise Technology Co., Ltd. Hexachloroiridium (IV) Acid Hydrate (H\u003csub\u003e2\u003c/sub\u003eIrCl\u003csub\u003e6\u003c/sub\u003e·6H\u003csub\u003e2\u003c/sub\u003eO) was purchased from Shanghai Yien Chemical Technology Co., Ltd. Ethylene glycol (EG), Triethylene glycol (TEG), Commercial iridium 5% on carbon (Commerical Ir/C) and Commercial ruthenium 5% on carbon (Commerical Ru/C) were purchased from Shanghai Macklin Biochemical Co., Ltd. Commercial platinum 20% on carbon (Commerical Pt/C) was purchased from Shanghai Hesen Electric Co., Ltd. Poly(vinylpyrrolidone) (K30) was purchased from Beijing Wokai Biotechnology Co., Ltd. All the materials were utilized without further purification.\u003c/p\u003e\u003ch3\u003eSynthesis of high-entropy alloy with face-centered cubic phase structure (fcc-RuPtIrRhOs HEA)\u003c/h3\u003e\u003cp\u003eIn a typical synthesis, 20 mL of TEG solution containing PVP (222 mg) was added into a 100-mL three-neck round bottom flask and and subsequently preheated at 230 \u003csup\u003eo\u003c/sup\u003eC in a heating mantle under magnetic stirring for 10 min. Then, 5 mL of TEG solution containing Ru(acac)\u003csub\u003e3\u003c/sub\u003e (23.9 mg), K\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e4\u003c/sub\u003e (4.5 mg), H\u003csub\u003e2\u003c/sub\u003eIrCl\u003csub\u003e6\u003c/sub\u003e·H\u003csub\u003e2\u003c/sub\u003eO (5.1 µL), Rh(acac)\u003csub\u003e3\u003c/sub\u003e (4.5 mg), and OsCl\u003csub\u003e3\u003c/sub\u003e (3.5 mg) was introduced dropwise into the reaction solution by a syringe pump at a specific rate of 0.1 mL/min after 20 min of ultrasonic treatment. The reaction was maintained at 230 ℃ under magnetic stirring for 2 h. After the reaction, the reaction mixture was quenched in an ice water bath and the fcc-RuPtIrRhOs HEA was collected by precipitation with a great amount of acetone and washed two times with a mixture of ethanol and acetone (1:3 v/v).\u003c/p\u003e\u003ch2\u003eSynthesis of high-entropy alloy with hexagonal close-packed phase structure (hcp-RuPtIrRhOs HEA)\u003c/h2\u003e\u003cp\u003eIn a typical synthesis, 20 mL of EG solution containing PVP (222 mg) was added into a 100-mL three-neck round bottom flask and and subsequently preheated at 200 in a heating mantle under magnetic stirring for 10 min. Then, 5 mL of EG solution containing K\u003csub\u003e2\u003c/sub\u003eRu(NO)Cl\u003csub\u003e5\u003c/sub\u003e (23.2 mg), Pt(acac)\u003csub\u003e2\u003c/sub\u003e (4.3 mg), H\u003csub\u003e2\u003c/sub\u003eIrCl\u003csub\u003e6\u003c/sub\u003e·H\u003csub\u003e2\u003c/sub\u003eO (5.1 µL), Rh(acac)\u003csub\u003e3\u003c/sub\u003e (4.5 mg), and OsCl\u003csub\u003e3\u003c/sub\u003e (3.5 mg) was introduced dropwise into the reaction solution by a syringe pump at a specific rate of 1 mL/min after 20 min of ultrasonic treatment. The reaction was maintained at 200 \u003csup\u003eo\u003c/sup\u003eC under magnetic stirring for 2 h. After the reaction, the reaction mixture was quenched in an ice water bath and the hcp-RuPtIrRhOs HEA was collected by precipitation with a great amount of acetone and washed two times with a mixture of ethanol and acetone (1:3 v/v).\u003c/p\u003e\u003ch2\u003eCharacterizations\u003c/h2\u003e\u003cp\u003eThe scanning transmission electron microscopy (STEM) imaging and energy-dispersive X-ray spectroscopy (EDS) mapping were acquired on JEOL JEM-ARM200CF and JEM-ARM300F2 electron microscope operated at 200 kV. The transmission electron microscopy (TEM) images were collected by JEM-F200 electron microscope, operating at 200 kV. The X-ray diffraction (XRD) characterizations were performed on SmartLab 9 kW diffractometer equipped with Cu-Kα radiation. X-ray photoelectron spectroscopy (XPS) measurements were conducted on a Thermo Scientific, ESCALAB 250Xi system. The inductively coupled plasma-optical emission spectrometry (ICP-OES) measurements were collected on Agilent 5110.\u003c/p\u003e\u003ch2\u003eElectrochemical Measurements\u003c/h2\u003e\u003cp\u003eAll electrochemical measurements were performed on a CHI 760 with a conventional three-electrode system, where glassy carbon, Hg/HgO, and graphite rod were utilized as the working electrode, reference electrode, and counter electrode, respectively. In a standard procedure for the preparation of catalyst samples, 1 mg of the HEA and 4 mg of carbon support (Vulcan XC-72R) were dispersed in a 1-mL mixed solution of isopropanol (710 µL), water (250 µL), and Nafion solution (40 µL, Sigma Aldrich 5 wt%). The catalyst was ultrasonic treated for at least 2 h. 10 µL of the catalyst ink were added to a polished glassy carbon rotating disk electrode in two aliquots with a geometric surface of 0.196 cm\u003csup\u003e2\u003c/sup\u003e and dried in the air at room temperature.\u003c/p\u003e\u003cp\u003eIn a typical electrocatalytic hydrogen evolution reaction (HER) measurement, the electrode was subjected to 50 cycles of cyclic voltammetry (CV) in Ar-saturated 1 M KOH with a high scan rate of 0.5 V/s to obtain a stable surface. The obtained potentials for all LSV curves were referenced to the reversible hydrogen electrode (RHE) and all polarization curves were presented with iR compensation. The linear sweep voltammetry (LSV) was conducted from − 0.90 to − 1.2 V (versus Hg/HgO) at a scan rate of 0.01 V/s and a rotating speed of 1600 rpm/s to evaluate the HER performance. For the long-term stability test, we carried out 10,000 cycles of CV in the same region as LSV for HER at 0.1 V/s. The corresponding Tafel plots were obtained by fitting the linear portion of the curve into the Tafel equation \u003cem\u003eη\u003c/em\u003e = b log (j) + a, in which b is the Tafel plot.\u003c/p\u003e\u003cp\u003eThe electrochemical active surface areas (ECSAs) of the three catalysts were further determined using Cu underpotential deposition (Cu\u003csub\u003eupd\u003c/sub\u003e) for analysis of catalytic performance. Briefly, the electrode was first cycled in Ar-saturated 0.5 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e from 0.01 to 1.1 V\u003csub\u003eRHE\u003c/sub\u003e at a scan rate of 10 mV s\u003csup\u003e− 1\u003c/sup\u003e after cleaning the electrode at 500 mV s\u003csup\u003e− 1\u003c/sup\u003e for several hundred cycles. Then, the potential was fixed at 0.3 V\u003csub\u003eRHE\u003c/sub\u003e for 100 s in an Ar-saturated aqueous electrolyte containing 0.5 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e and 5 mM CuSO\u003csub\u003e4\u003c/sub\u003e followed by a linear scan from 0.3 to 1.1 V\u003csub\u003eRHE\u003c/sub\u003e to collect the Cu\u003csub\u003eupd\u003c/sub\u003e curve. The ECSAs were calculated by integrating the stripping charge of Cu\u003csub\u003eupd\u003c/sub\u003e and subtracting the charge obtained under the same conditions in 0.5 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e, assuming a charge density of 420 µC. The ECSA can be calibrated as:\u003c/p\u003e\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e\n$$\\:ECSA=\\frac{{Q}_{Cu}}{{m}_{metal}\\times\\:420\\:\\mu\\:C\\:{cm}^{-2}}$$\u003c/div\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003ewhere m\u003csub\u003emetal\u003c/sub\u003e is the mass loading of the noble metal on a certain geometric area of the working electrode and 420 µC cm\u003csup\u003e− 2\u003c/sup\u003e is the value of charge consumed for the formation of a Cu\u003csub\u003eupd\u003c/sub\u003e monolayer on active metal sites.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor contributions\u003c/h2\u003e \u003cp\u003eY.L.Z. conceived the research concept. L.F., M.Q.Z., and W. Z. supervised the research. Y.L.Z. carried out the main experiments, collected and analyzed the data. X.J.P. performed transmission electron microscopy characterizations, collected and analyzed the data. L.F., M.Q.Z., W. Z., Y.L.Z., and X.J.P. cowrote the manuscript. All the authors contributed to data analysis and scientific discussion.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThe research was supported by the Natural Science Foundation of China (Grants 22025303), the CAS Project for Young Scientists in Basic Research (YSBR-003), and the Fundamental Research Funds for the Central Universities. We would like to acknowledge the Center for Electron Microscopy at Wuhan University for their substantial support to TEM characterization. We also thank the Electron Microscopy Center at the University of Chinese Academy of Sciences for the STEM work. We also thank the Core Facility of Wuhan University for providing the ICP-OES and XPS tests, and the Core Research Facilities of the College of Chemistry and Molecular Sciences at Wuhan University for the XRD characterization. We also thank the Institute for Advanced Studies of Wuhan University for their assistance in TEM characterization.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eThe data that support the findings of this study are available from the corresponding authors on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLi M et al (2024) High-entropy alloy electrocatalysts go to (sub-)nanoscale. Sci Adv 10:eadn2877\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDing Z et al (2025) The integral role of high-entropy alloys in advancing solid-state hydrogen storage. Interdiscip Mater 4:75\u0026ndash;108\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAn Z et al (2024) Negative mixing enthalpy solid solutions deliver high strength and ductility. \u003cem\u003eNature\u003c/em\u003e 625, 697\u0026thinsp;\u0026ndash;\u0026thinsp;702\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang J et al (2024) High-entropy alloy array via liquid metal nanoreactor. Adv Mater 36:2403865\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJung S-G et al (2022) High critical current density and high-tolerance superconductivity in high-entropy alloy thin films. Nat Commun 13:3373\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang J, Cao G, Zeng M, Fu L (2024) Controllable synthesis of high-entropy alloys. Chem Soc Rev 53:6021\u0026ndash;6041\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYao Y et al (2022) High-entropy nanoparticles: Synthesis-structure-property relationships and data-driven discovery. Science 376:eabn3103\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi L et al (2022) Phase engineering of a ruthenium nanostructure toward high-performance bifunctional hydrogen catalysis. ACS Nano 16:14885\u0026ndash;14894\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTan X et al (2020) Closest packing polymorphism interfaced metastable transition metal for efficient hydrogen evolution. Adv Mater 32:2002857\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Q et al (2015) New approach to fully ordered fct-FePt nanoparticles for much enhanced electrocatalysis in acid. Nano Lett 15:2468\u0026ndash;2473\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFan Z et al (2015) Stabilization of 4H hexagonal phase in gold nanoribbons. Nat Commun 6:7684\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNguyen YN et al (2025) Facile synthesis of rhodium-based nanocrystals in a metastable phase and evaluation of their thermal and catalytic properties. Small Methods 9:2401143\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang J et al (2023) Kinetic-modulated crystal phase of Ru for hydrogen oxidation. Small 19:2207038\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYun Q et al (2019) Synthesis of PdM (M\u0026thinsp;=\u0026thinsp;Zn, Cd, ZnCd) nanosheets with an unconventional face-centered tetragonal phase as highly efficient electrocatalysts for ethanol oxidation. ACS Nano 13:14329\u0026ndash;14336\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang X et al (2024) Facet-controlled synthesis of unconventional-phase metal alloys for highly efficient hydrogen oxidation. J Am Chem Soc 146:24141\u0026ndash;24149\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYao Q, Yu Z, Li L, Huang X (2023) Strain and surface engineering of multicomponent metallic nanomaterials with unconventional phases. Chem Rev 123:9676\u0026ndash;9717\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYun Q et al (2023) Recent progress on phase engineering of nanomaterials. \u003cem\u003eChem. Rev.\u003c/em\u003e 123, 13489\u0026thinsp;\u0026ndash;\u0026thinsp;13692\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCui M et al (2022) Multi-principal elemental intermetallic nanoparticles synthesized via a disorder-to-order transition. Sci Adv 8:eabm4322\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakamura M et al (2023) B2-structured indium-platinum group metal high-entropy intermetallic nanoparticles. Chem Commun 59:9485\u0026ndash;9488\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu J, Zhang Y, Ding Y, Zeng M, Fu L (2024) Atomic design of high-entropy alloys for electrocatalysis. ACS Mater Lett 6:2642\u0026ndash;2659\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi H, Lai J, Li Z, Wang L (2021) Multi-sites electrocatalysis in high-entropy alloys. Adv Funct Mater 31:2106715\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eL\u0026ouml;ffler T, Ludwig A, Rossmeisl J, Schuhmann W (2021) What makes high-entropy alloys exceptional electrocatalysts? Angew Chem Int Ed 60:26894\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYao Y et al (2018) Carbothermal shock synthesis of high-entropy-alloy nanoparticles. \u003cem\u003eScience\u003c/em\u003e 359, 1489\u0026thinsp;\u0026ndash;\u0026thinsp;1494\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao J-Z, Ahmed T, Jiang H-X, He J, Sun Q (2017) Solidification of immiscible alloys: A review. Acta Metall Sin (Engl Lett 30:1\u0026ndash;28\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen P-C et al (2019) Interface and heterostructure design in polyelemental nanoparticles. \u003cem\u003eScience\u003c/em\u003e 363, 959\u0026thinsp;\u0026ndash;\u0026thinsp;964\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu H et al (2024) Unveiling atomic-scaled local chemical order of high-entropy intermetallic catalyst for alkyl-substitution-dependent alkyne semihydrogenation. J Am Chem Soc 146:20193\u0026ndash;20204\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Y et al (2023) Laser annealing-induced phase transformation behaviors of high entropy metal alloy, oxide, and nitride nanoparticle combinations. Adv Funct Mater 33:2211279\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang Y et al (2021) Determining the three-dimensional atomic structure of an amorphous solid. \u003cem\u003eNature\u003c/em\u003e 592, 60\u0026thinsp;\u0026ndash;\u0026thinsp;64\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Q et al (2022) Crystal structure control of binary and ternary solid-solution alloy nanoparticles with a face-centered cubic or hexagonal close-packed phase. J Am Chem Soc 144:4224\u0026ndash;4232\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Q et al (2018) Selective Control of Fcc and Hcp Crystal Structures in Au\u0026ndash;Ru Solid-Solution Alloy Nanoparticles. Nat Commun 9:510\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLaMer VK, Dinegar RH (1950) Theory, production and mechanism of formation of monodispersed hydrosols. J Am Chem Soc 72:4847\u0026ndash;4854\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou M et al (2016) Quantitative analysis of the reduction kinetics responsible for the one-pot synthesis of Pd\u0026ndash;Pt bimetallic nanocrystals with different structures. J Am Chem Soc 138:12263\u0026ndash;12270\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKar N et al (2024) Retrosynthetic design of core\u0026ndash;shell nanoparticles for thermal conversion to monodisperse high-entropy alloy nanoparticles. Nat Synth 3:175\u0026ndash;184\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLao X et al (2023) Pd-enriched-core/Pt-enriched-shell high-entropy alloy with face-centred cubic structure for C1 and C2 alcohol oxidation. Angew Chem Int Ed 62:e202304510\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang C et al (2023) Facet-controlled synthesis of platinum-group-metal quaternary alloys: The case of nanocubes and {100} facets. J Am Chem Soc 145:2553\u0026ndash;2560\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNguyen QN et al (2024) Elucidating the role of reduction kinetics in the phase-controlled growth on preformed nanocrystal seeds: A case study of Ru. J Am Chem Soc 146:12040\u0026ndash;12052\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang X et al (2024) Regioselective epitaxial growth of metallic heterostructures. Nat Nanotechnol 19:1306\u0026ndash;1315\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGao W et al (2019) Probing the dynamics of nanoparticle formation from a precursor at atomic resolution. Sci Adv 5:eaau9590\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang C, He J, Xia Y (2024) Controlling the composition and elemental distribution of bi- and multi-metallic nanocrystals via dropwise addition. Nat Synth 3:1076\u0026ndash;1082\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu Y-H et al (2023) Toward controllable and predictable synthesis of high-entropy alloy nanocrystals. Sci Adv 9:eadf9931\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSun Y et al (2021) Modulating electronic structure of metal-organic frameworks by introducing atomically dispersed Ru for efficient hydrogen evolution. Nat Commun 12:1369\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang J et al (2023) Ir nanoparticles anchored on metal-organic frameworks for efficient overall water splitting under pH-universal conditions. Angew Chem Int Ed 62:e202302220\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang Q et al (2025) Size-controllable high-entropy alloys toward stable hydrogen production at industrial-scale current densities. Adv Mater 37:2420173\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMao Q et al (2023) Multisite synergism-induced electron regulation of high-entropy alloy metallene for boosting alkaline hydrogen evolution reaction. Adv Funct Mater 33:2304963\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKang Y et al (2023) Mesoporous multimetallic nanospheres with exposed highly entropic alloy sites. Nat Commun 14:4182\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCui X et al (2024) Rapid high-temperature liquid shock synthesis of high-entropy alloys for hydrogen evolution reaction. ACS Nano 18:2948\u0026ndash;2957\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFeng G et al (2021) Sub-2 nm ultrasmall high-entropy alloy nanoparticles for extremely superior electrocatalytic hydrogen evolution. J Am Chem Soc 143:17117\u0026ndash;17127\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang C et al (2024) Octahedral nanocrystals of Ru-doped PtFeNiCuW/CNTs high-entropy alloy: High performance toward pH-universal hydrogen evolution reaction. Adv Mater 36:2400433\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMahin J et al (2025) All iron-group and platinum-group elements metal high-entropy alloy nanoparticles. Angew Chem Int Ed 64:e202502552\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8308350/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8308350/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHigh-entropy alloys (HEAs) have already shown great promise for a range of emerging applications, particularly in catalysis, yet their development is constrained by an unresolved challenge: the incompatibility between achieving high configurational entropy and precise crystal phase control. Here, we introduced a redox-mediated kinetic engineering strategy that simultaneously fulfilled both criteria by decoupling nucleation and growth processes. Through staged modulation of reduction potentials\u0026mdash;first creating kinetic divergence for phase-specific nucleation, then enabling rapid co-reduction for high-entropy products, we achieved HEAs with tailored crystal structures. Distinct hydrogen evolution performance between different crystalline phases of HEAs unequivocally demonstrated the critical role of crystal phase in determining catalytic properties. The developed synthetic paradigm provided a general route to manipulate HEA phases while preserving high entropy, opening new possibilities for tailored materials design in catalysis and beyond.\u003c/p\u003e","manuscriptTitle":"Tailoring Crystal Phase of High-Entropy Alloy Nanoparticles via Redox-Mediated Engineering","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-23 06:58:04","doi":"10.21203/rs.3.rs-8308350/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"762c7b33-7c07-4d0e-816e-a96e1f82fe2c","owner":[],"postedDate":"December 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":59976314,"name":"Physical sciences/Materials science/Materials for energy and catalysis"},{"id":59976315,"name":"Physical sciences/Nanoscience and technology/Nanoscale materials"}],"tags":[],"updatedAt":"2026-05-04T18:40:58+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-23 06:58:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8308350","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8308350","identity":"rs-8308350","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}