Reaction-induced regioselective reconstruction of Ni-doped Ce(OH)3/CeO2 enables exceptional activity and selectivity for reverse water-shift reaction

Reaction-induced regioselective reconstruction of Ni-doped Ce(OH)3/CeO2 enables exceptional activity and selectivity for reverse water-shift reaction | 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 Reaction-induced regioselective reconstruction of Ni-doped Ce(OH)3/CeO2 enables exceptional activity and selectivity for reverse water-shift reaction Yongquan Qu, Wenbin Li, Bing Liu, Qing Guo, Wenjie Guo, Sai Zhang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5258008/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Reconstruction of catalysts by reaction environments represents a viable approach to create highly performed active sites. Herein, we developed a reaction-induced regioselective reconstruction of Ni-doped Ce(OH) 3 /CeO 2 nanorods to form dual-active sites composed of carburized Ni clusters and frustrated Lewis pairs (FLPs), delivering exceptional activity, selectivity and stability for reverse water-gas shift reaction. Ni aggregation in the Ce(OH) 3 region, coupled with in-situ carbonization of Ni by catalytically generated CO during reaction, induced the formation of the carburized Ni clusters, which effectively promoted H 2 dissociation. Additionally, Ni doping in the CeO 2 region and Ce(OH) 3 -to-CeO 2 phase transition introduced more oxygen vacancies and thereby generated FLPs in CeO 2 , which facilitated CO 2 adsorption and subsequent hydrogenation by spilled H* species from the carburized Ni clusters. Weak CO adsorption on both the carburized Ni clusters and FLPs significantly suppressed the methanation side-reaction. This reaction-induced regioselective reconstruction strategy provides a new avenue for designing highly performed catalysts. Physical sciences/Chemistry/Catalysis/Heterogeneous catalysis Physical sciences/Chemistry/Green chemistry/Sustainability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Development of advanced catalysts to achieve exceptional activity and selectivity is an ambitious but challenging topic for addressing the global challenges of climate, energy security and environmental sustainability. 1-3 Currently, the cutting-edge efforts have been focused on acquiring precisely defined active sites with the meticulously pre-designed geometric and/or electronic structures. 4-7 However, their structures ( e.g. , sizes, phases, local coordination environments) can be significantly affected by the reaction conditions, generally leading to decayed catalytic performance. 8,9 Meanwhile, recent advances have revealed that the reconstruction of catalysts induced by adsorbed species and/or catalytic environments can progressively produce new active sites with the dramatically improved catalytic performance. 10-16 Practically, those reconstructions are challenging to attain through conventional preparation methods. Unfortunately, one irresistibly drawback of the reaction-induced reconstruction strategy is lack of the precise controllability on the pre-designed active sites of catalysts into the anticipated new ones with highly performance. Besides that, since a reaction generally involves multiple reactants, another fundamental paradox arises from the entire surface region of heterogeneous catalysts under the reconstruction in response to the reaction environments, which may be unpropitious to the simultaneous co-adsorption and activation of multiple reactants. 17-20 Motivated by the existential concerns of the reaction-induced reconstruction and encouraged by prior cognitions of the contributions of multiple active sites for co-activation of several molecules on the improved catalytic performance, a novel methodology is anticipated to achieve the precisely controllable and/or regioselective reconstruction of a pre-catalyst under a specific reaction environment. Specifically, this approach can enable in situ creation of multiple active sites with distinct local environments, facilitating the effective co-activation of all reactants in catalytic reactions. Herein, we demonstrate the reaction-induced regioselective reconstruction of the Ni-doped Ce(OH) 3 /CeO 2 nanorod (Ni-Ce(OH) 3 /CeO 2 ) catalysts to construct the dual-active sites of the creatively carburized Ni clusters and precisely designed frustrated Lewis pairs (FLPs), thereby enabling exceptionally active, selective and robust catalytic performance for reverse water-gas shift (RWGS) reaction. During RWGS, the thermal decomposition of Ce(OH) 3 into CeO 2 triggered the selective aggregation of the Ni dopants into Ni clusters in the region of Ce(OH) 3 , which simultaneously underwent the carbonization by the catalytically generated carbon monoxide (CO) to create new carburized Ni clusters. Additionally, the Ce(OH) 3 -to-CeO 2 phase transition generated more structural defects of oxygen vacancy in the reconstructed Ce(OH) 3 region. Combining the precisely designed defective Ni-doped CeO 2 , these high levels of oxygen vacancies in the regioselective reconstructed catalysts resulted in the formation of abundant FLP sites. 21-23 The synergistic effect of the carburized Ni clusters and FLP sites delivered high capability for the adsorption and activation of H 2 and CO 2 , respectively. Simultaneously, the weak CO adsorption on the FLPs and carburized Ni clusters with the downward shift of the d -band effectively suppressed the methanation side-reaction. Hydrogen spillover from the carburized Ni clusters to the FLP sites enabled a CO generation rate of 27.3 mol g Ni -1 h -1 with a selectivity of >99.9% for the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts at 550 °C, surpassing those of previous reports by at least one order of magnitude. Moreover, the Ni-Ce(OH) 3 /CeO 2 catalysts operated stably and continuously for at least 1000 h. Results Theoretical analysis Recently, we have demonstrated both theoretically and experimentally the effective CO 2 activation even at temperatures below 100°C by the constructed FLP sites on the defective CeO 2 (110) surface with two adjacent oxygen vacancies (CeO 2 (110)-2O V ), consisting of the lattice O 2− as Lewis base and two neighboring Ce 3+ as Lewis acid (Fig. 1 a). 22 , 23 Density functional theory (DFT) calculations reveal the much stronger CO 2 adsorption on FLP(Ce 3+ /Ce 3+ …O 2− ) through a bridged configuration compared to that on the ideal CeO 2 (110) surface (Fig. 1 b, S1 and S2). Conversely, the relatively weak H 2 adsorption is theoretically profiled on both ideal CeO 2 (110) and FLP sites in comparation to the strong CO 2 adsorption on the same FLP site (Fig. 1 b, S1 and S2). Therefore, the competitive adsorption of H 2 and CO 2 on the defective CeO 2 (110) indicates the failure of their simultaneous activation, leading to the poor RWGS activity of CeO 2 with FLPs alone in our previous report. 24 Recently, the Ni-doped or Ni-anchored CeO 2 catalysts have been extensively investigated for H 2 dissociation and subsequent CO 2 hydrogenation. 25 – 29 To address the impact of Ni, we theoretically investigated the chemical-doping of Ni in CeO 2 by replacing one of Ce 3+ of FLPs or one lattice Ce in the subsurface, as well as examined Ni clusters on CeO 2 surface. As revealed from the DFT calculations (Fig. 1 b, S3 and S4), the adsorption energy of CO 2 is still much higher than that of H 2 on the FLP sites of both CeO 2 and Ni-doped CeO 2 . Subsequently, a Ni 4 cluster supported on the surface of CeO 2 (110)-2O V (Ni 4 /CeO 2 (110)-2O V configuration) is constructed. It is noteworthy that the Ni 4 cluster exhibits a strong dissociative adsorption ability for H 2 (-1.0 eV) in comparison of CO 2 adsorption (-0.64 eV, Figure S5). These findings suggest that H 2 and CO 2 molecules can be co-activated on the Ni 4 /CeO 2 (110)-2O V system, where the Ni 4 clusters and FLPs act as dual-active sites for the adsorption of H 2 and CO 2 , respectively, effectively avoiding their intensely competitive adsorption. Theoretically, the construction of dual-active sites of Ni clusters and FLP sites on the defective CeO 2 (110) surface holds promise to enable the highly performed RWGS reaction. However, the utilization of Ni nanocatalysts generally induces a significant methanation side reaction. 29 – 32 Experimental results demonstrated the enhanced RWGS activity of the Ni clusters deposited on PN-CeO 2 (Ni cluster /PN-CeO 2 ) with FLP sites at the expense of the decreased selectivity of CO and increased selectivity of CH 4 (Figure S6). The methanation side-reaction is attributed to the strong adsorption of CO on Ni clusters and then over-hydrogenation of CO into CH 4 . 33 – 37 According to the d -band theory, the binding strength between metal and guest molecules is determined by the filling degree of the antibonding state. 38 , 39 Introducing carbon atoms into metal clusters can effectively tailor the d -band center of metals. 14 , 40 , 41 Carbon has been demonstrated to be highly miscible in Ni lattice, followed by the surface diffusion and formation of carbide-like phases. 42 Motivated by this recognition, the density of states (DOS) of Ni 3d orbital in both Ni 4 /CeO 2 (110) and carburized Ni 4 /CeO 2 (110) (Note: A carbon atom was introduced into the surface of Ni 4 cluster) were investigated. It was evident that the presence of a carbon atom on the Ni 4 cluster modulates both spin-up and spin-down states, causing a downward shift of the d -band center of Ni from − 1.07 eV to -1.86 eV (Fig. 1 c). Consequently, the CO adsorption on the carburized Ni 4 cluster is weakened, as evidenced by the comparison of CO adsorption energy on the carburized Ni 4 /CeO 2 (110) and Ni 4 /CeO 2 (110) surfaces (-1.98 eV vs. -2.13 eV, Figure S7). Based on the theoretical analysis, the highly performed RWGS reaction can be realized by the rationally designed dual-active sites of the carburized Ni clusters and FLPs on CeO 2 surface, which involves (Fig. 1 d): ( I ) the spontaneous dissociation of H 2 molecules on the carburized Ni clusters to generate active H* species; ( II ) the efficient activation of CO 2 molecules FLPs and subsequent hydrogenation into CO by the spilled H*; and ( III ) the effectively suppressed the methanation side reaction through weak desorption of CO on both carburized Ni clusters and FLPs. However, the carburized Ni clusters anchored on the surface of CeO 2 with FLP sites is hardly to be synthesized through various conventional methods. Recently, the in situ reactant/product-induced reconstruction has emerged as a promising avenue to generate new highly efficient carbide-like active sites. 14 , 40 Inspired by these findings, it stimulates our efforts to develop a new methodology to synthesize a pre-catalyst, which is capable of facilitating the reaction-induced reconstruction to give the carburized Ni clusters while simultaneously ensuring the precisely designed FLP sites under the catalytic environment of RWGS. Synthesis and characterizations of Ni-doped Ce(OH) 3 /CeO 2 nanorods Considering the facile synthesis of Ni-doped CeO 2 , the thermally induced Ni aggregation and subsequently reconstituted the carburized Ni clusters might provide an approach to construct the dual-active site during RWGS owing to the high temperature and abundant carbon resources (CO, CO 2 , et. al. ) of the reaction environment. However, the migration of Ni in Ni-doped CeO 2 is highly energy-consuming due to the strong confinement of Ni dopant within CeO 2 lattice, leading to the difficulty to drive the Ni aggregation. To overcome this challenge and achieve the theoretically proposed dual-active sites, herein, the Ni-doped Ce(OH) 3 /CeO 2 (Ni-Ce(OH) 3 /CeO 2 ) pre-catalysts were synthesized through a low-pressure hydrothermal method at 100°C, incorporating varying levels of Ni loading. As illustrated in Fig. 2 a, different from the stable Ni-doped CeO 2 , the unstable Ce(OH) 3 component undergoes a regioselective reconstruction into CeO 2 through the thermal decomposition and oxidation during RWGS, accompanied by the formation of Ni clusters, which could in situ form the carburized Ni clusters by the catalytically generated CO. Importantly, the FLPs sites within the stable CeO 2 component could remain unaffected. On this occasion, the dual-active sites of the creatively carburized Ni clusters and precisely designed FLPs would be came into being through the in situ regioselective reconstruction of the Ni-Ce(OH) 3 /CeO 2 pre-catalysts. Powder X-ray diffraction (XRD) analysis of the Ni-Ce(OH) 3 /CeO 2 pre-catalysts revealed the formation of a mixed phase of Ce(OH) 3 and CeO 2 with a molar ratio of 0.51:0.49 (Fig. 2 b). The replacement of relatively larger Ce ions by smaller Ni ions induced a slight shift of the (111) plane of Ce(OH) 3 in comparison with that of Ce(OH) 3 /CeO 2 (synthesized by the same process without Ni precursor, Figure S8 and S9). Furthermore, transmission electron microscopy (TEM) imaging of the Ni-Ce(OH) 3 /CeO 2 pre-catalysts did not detect any nickel oxide or metallic nickel species (Fig. 2 c and S10). Notably, the high-resolution TEM image of Ni-Ce(OH) 3 /CeO 2 revealed the lattice fringes of 0.30 nm and 0.19 nm (Fig. 2 c), which corresponded to the (101) crystal face of Ce(OH) 3 and (220) crystal face of CeO 2 , respectively. Catalytic performance of Ni-Ce(OH)/CeO for RWGS Subsequently, the catalytic performance of the Ni-Ce(OH) 3 /CeO 2 pre-catalysts with various Ni loadings for RWGS was evaluated in a fixed bed reactor using a feed gas mixture of H 2 :CO 2 (3:1) with a weighted hourly space velocity (WHSV) of 72,000 mL g cat −1 h − 1 . Their catalytic performances suggested that the optimal Ni content was 0.5 wt. % (Figure S11). Therefore, Ni-Ce(OH) 3 /CeO 2 mentioned later in this study was referred to the catalysts with a Ni doping of 0.5 wt. %. To highlight the catalytic performance of the Ni-Ce(OH) 3 /CeO 2 pre-catalysts, the Ce(OH) 3 /CeO 2 (Figure S8) and Ni-doped CeO 2 catalysts with Ni loading of 0.5 wt. % (Ni-CeO 2 , Figure S12) were also prepared. Specifically, the Ce(OH) 3 /CeO 2 catalysts with only FLP sites exhibited the lowest CO 2 conversion, which could be attributed to its poor capability for the co-activation of H 2 and CO 2 (Figure S13). Introduction of Ni dramatically boosted the catalytic activity of Ni-Ce(OH) 3 /CeO 2 and Ni-CeO 2 . Notably, the Ni-Ce(OH) 3 /CeO 2 catalysts exhibited a significantly higher CO 2 conversion than that of Ni-CeO 2 at each reaction temperature. Furthermore, similar to the Ce(OH) 3 /CeO 2 catalysts, high selectivity towards CO (> 99.9%) was impressively observed for both Ni-Ce(OH) 3 /CeO 2 and Ni-CeO 2 , even at very high conversions of CO 2 (Figure S13). Consequently, with the highest CO 2 conversion and near 100% CO selectivity, the Ni-Ce(OH) 3 /CeO 2 catalysts undoubtedly achieved the highest CO yield at each temperature (Fig. 2 d). More importantly, the CO yield of Ni-Ce(OH) 3 /CeO 2 reached 55.0% at 550°C, which closely approached the equilibrium CO yield of 55.1% for RWGS under the operation conditions (Fig. 2 d). Consequently, the Ni-Ce(OH) 3 /CeO 2 catalysts exhibited an exceptionally high CO generation rate of 27.3 mol g Ni −1 h − 1 , surpassing the previously reported Ni-based catalysts by at least one order of magnitude with a similar CO selectivity (Fig. 2 f and Table S1 ). Although a few catalysts in the literature exhibited a comparable activity in the CO generation rate, their CO selectivity was significantly lower than that of Ni-Ce(OH) 3 /CeO 2 (Fig. 2 f and Table S1 ). Additionally, the Ni-Ce(OH) 3 /CeO 2 catalysts delivered remarkable stability for RWGS even at a high temperature of 550°C. The CO yields remained nearly constant and approached the thermodynamic equilibrium yield for at least 1000 h of reaction (Fig. 2 f and S14). Furthermore, each Ni stie achieved an impressively high turnover frequency of > 4,500,000. Identification of the reaction-driven reconstruction of Ni-Ce(OH)/CeO Considering the ease of the Ce(OH) 3 decomposition, the phase of the spent Ni-Ce(OH) 3 /CeO 2 catalysts was examined through XRD analysis. The observed phase transformation from the mixed Ce(OH) 3 /CeO 2 phase into pure CeO 2 strongly suggested the in situ regioselective reconstruction of the Ni-Ce(OH) 3 component within Ni-Ce(OH) 3 /CeO 2 during RWGS (Fig. 2 b and S9). This finding is close alignment with our initial design (Fig. 2 a). Consequently, it became imperative to conduct a comprehensive analysis of the evolution of the surface properties of Ni-Ce(OH) 3 /CeO 2 under the operation, thereby understanding the reconstruction during RWGS and identifying the key factor for their exceptional catalytic performance in comparison with the Ni-CeO 2 catalysts and other state-of-the-art catalysts (Fig. 2 e). To illustrate the occurrence of the reaction-driven reconstruction process, the RWGS reaction was conducted by transferring the Ni-Ce(OH) 3 /CeO 2 pre-catalysts at room temperature into the pre-heated reactor at the desired temperatures. An obvious activation period for Ni-Ce(OH) 3 /CeO 2 was experimentally observed as evidenced by their gradually improved CO 2 conversions during the initial 8.5 h at 400°C (Fig. 3 a). Notably, the activation periods were significantly shortened from 8.5 h to 1.5 h with the increased reaction temperatures from 400°C to 600°C. This observed activation period unequivocally demonstrated the formation of new active sites through a reaction-driven reconstruction of Ni-Ce(OH) 3 /CeO 2 during the RWGS process. Then, the aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) was employed to examine the structural changes of the catalysts, illustrating the well maintained nanorod structure with the evolution of mesoporous morphology of the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts (Fig. 3 b). The measured lattice spacing of 0.190 nm also indicated the preservation of (220) crystal face of CeO 2 (Fig. 3 c). Importantly, small clusters were observed on the surface of the reconstructed catalysts (Fig. 3 c). Moreover, the X-ray photoelectron spectroscopy (XPS) analysis on Ni 2 p orbital electrons revealed the fraction of Ni 0 species from virtually zero in the pre-catalysts to 44.3% in the reconstructed ones, strongly suggesting the occurrence of the reaction-driven reconstruction of the Ni dopant in the Ni-Ce(OH) 3 /CeO 2 pre-catalysts into Ni clusters (Figure S15). In contrast, no observed Ni 0 species in the spent Ni-CeO 2 catalysts indicated that the Ni dopants in CeO 2 region did not undergo the reconstruction, confirming the regioselective reconstruction as proposed in Fig. 2 a. Next, X-ray absorption fine structure (XAFS) spectroscopy was employed to examine the reaction-driven reconstruction of Ni-Ce(OH) 3 /CeO 2 . The adsorption edge of the Ni-Ce(OH) 3 /CeO 2 pre-catalysts exhibited a negative displacement compared to the NiO foil (Fig. 3 d), suggesting the electron transfer from Ce to Ni sites. Comparatively, the electronic structures of the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts closely resembled to these of Ni foil, indicating the formation of metallic Ni during RWGS. The EXAFS spectra and wavelet-transform (WT) analysis revealed the presence of Ni-Ni bonds at a distance of 2.18 Å in the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts, consistent with the peak position of Ni-Ni observed in the Ni foil (Fig. 3 e and 3 f). Notably, the presence of Ni-O bonds was still evident on the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts (Fig. 3 e, 3 f and Table 1 ), indicating the unchanged structure of the doped Ni in the CeO 2 region. Therefore, combining TEM, XRD and XPS results, the XAFS spectra provided crucial evidences to illustrate the reaction-driven reconstruction of the Ni dopants in the specific region of Ce(OH) 3 of the pre-catalysts into Ni clusters. Table 1 Structure parameters of Ni-Ce(OH) 3 /CeO 2 and reconstructed Ni-Ce(OH) 3 /CeO 2 derived from the Ni K -edge EXAFS fitting results. Sample Paths N R (Å) σ 2 (×10 − 3 Å 2 ) NiO Ni-O 1.9 ± 0.5 1.56 ± 0.21 5.8 ± 1.3 Ni-O 5.0 ± 0.3 2.54 ± 0.11 6.0 ± 0.6 Ni-Ce(OH) 3 /CeO 2 Ni-O 2.1 ± 0.6 1.60 ± 0.12 11.6 ± 2.8 Ni-O 4.1 ± 0.9 2.55 ± 0.02 10.8 ± 3.7 Reconstructed Ni-Ce(OH) 3 /CeO 2 Ni-O 1.4 ± 0.6 1.58 ± 0.51 7.0 ± 2.0 Ni-Ni 11.0 ± 1.0 2.18 ± 0.01 10.4 ± 1.5 Ni-O 5.0 ± 1.0 2.61 ± 0.31 10.4 ± 1.5 Ni foil Ni-Ni 11.9 ± 0.6 2.15 ± 0.53 5.1 ± 0.6 Characterizations on the carburized Ni clusters Based on the above comprehensive analysis, the reaction-driven reconstruction of Ni-Ce(OH) 3 /CeO 2 created the Ni clusters on CeO 2 surface. Impressively, the reconstructed catalysts exhibited a dramatically high selectivity towards CO, suggesting that the local environments of these reaction-driven reconstructed Ni clusters in Ni-Ce(OH) 3 /CeO 2 were significantly distinct from those of commonly deposited Ni clusters and/or nanoparticles on various supports in previous studies. 43 , 44 As evidenced by the XPS profile of the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts, in addition to the presence of Ni 0 species, a small fraction of nickel carbide was detected at 850.3 eV (Figure S15a). Furthermore, the presence of Ni-C species was also revealed from C 1s spectrum with a peak at 283.8 eV (Figure S15b). Considering the carbon-rich environment conducive to a partial carbonization of metal clusters during RWGS, 41 , 45 , 46 the XPS profiles strongly supported the formation of the carburized Ni clusters during the reconstruction process. The time-depended synchrotron radiation photoelectron spectroscopy (SRPES) was conducted on the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts to examine the chemical states of the Ni clusters by an Ar plasma etching. As depicted in Fig. 3 g, the Ni L -edge of the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts indicated the co-existence of Ni 0 and Ni 2+ species, again confirming the formation of the Ni clusters. The C species as revealed from C K -edge gradually diminished with the continuously prolonged Ar plasma treatment, indicating the etching of carbonaceous species (Fig. 3 h). Furthermore, the significant shift towards the lower binding energy of Ni 0 species was observed as the decrease of C species, indicating a strong interaction between C species and Ni clusters through the electron transfer from Ni to C. Additionally, the higher binding energy of Ni 2+ species suggested the change in coordination from C to O on the CeO 2 surface, accompanied by the etching of C species. Therefore, the SRPES spectra analysis unambiguously demonstrated the environmental-induced reconstruction and carbonization to give the carburized Ni clusters. Afterwards, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was employed under various gaseous environments to investigate how the reconstruction occurred to form the carburized Ni clusters during RWGS. The DRIFTS profile of the Ni-Ce(OH) 3 /CeO 2 pre-catalysts exhibited a twin adsorption of Ni-(CO) 2/3 on the catalyst surface (Fig. 3 i), indicating the atomically dispersed Ni. Following the in situ treatment of Ni-Ce(OH) 3 /CeO 2 with H 2 /CO 2 at 350°C to mimic the catalytic environments, a noticeable reduction in the peak corresponding to Ni-(CO) 2/3 was observed (Fig. 3 i). Simultaneously, the emerging peaks at 1930 cm − 1 and 1840 cm − 1 were attributed to the bridged adsorption of CO with three Ni atoms (Ni 3 -CO) and the carbonization Ni species (NiC-CO), respectively. 47 , 48 However, no adsorption of NiC-CO was observed at 1840 cm − 1 on the H 2 -treated Ni-Ce(OH) 3 /CeO 2 catalysts. Additionally, the characteristic peaks of NiC-CO were also observed in the CO treated Ni-Ce(OH) 3 /CeO 2 catalysts (Fig. 3 i). Therefore, these experiments unequivocally demonstrated the crucial roles of the reductive CO for the formation of the carburized Ni clusters. Based on the aforementioned analysis, the Ni-doped Ce(OH) 3 component underwent the decomposition and oxidation to give CeO 2 as well as the aggregated Ni clusters, which were carbonized into the carburized Ni clusters by CO generated from the catalytic environment of RWGS. Furthermore, XPS data revealed a slight enhancement in oxygen vacancy concentration of the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts compared to the pre-catalysts (Figure S16), indicating the preservation of FLP sites. 22 , 23 Additionally, both CO 2 conversion and CO selectivity of the Ni-Ce(OH) 3 /CeO 2 catalysts remained nearly unchanged at 550°C for at least 1000 h (Figure S14), indicating the stability of the reaction-driven formation of the carburized Ni clusters and FLPs during RWGS. Carburized Ni clusters for the elimination of the competitive adsorption As proposed from theoretical analysis, the reaction-driven reconstruction of the Ni-Ce(OH) 3 /CeO 2 catalysts during RWGS created the dual-active sites of the carburized Ni clusters and FLP sites, which selectively activated H 2 and CO 2 , respectively and thereby significantly mitigated their pronounced co-adsorption and activation on the reconstructed catalyst surface (Fig. 1 b). The experiments for determining the reaction orders of H 2 and CO 2 at 300°C and 500°C for various catalysts were performed within the kinetic range to confirm the alleviated competitive adsorption on the constructed dual-active sites (Figure S17). Theoretically, as the reaction order of a reactant increases, its coverage on the catalyst surface is expected to decrease. 49 , 50 In comparison with both the Ni-CeO 2 and reconstructed Ce(OH) 3 /CeO 2 catalysts, the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts exhibited the lowest reaction orders of both H 2 and CO 2 (Fig. 4 a and 4 b), indicating the highest coverage of both H 2 and CO 2 on the reconstructed catalyst surface. Therefore, the simultaneous enhancement of H 2 and CO 2 coverages revealed their efficient co-adsorption on the surface of the reconstructed catalysts with the dual-active sites of the carburized Ni clusters and FLP sites. On the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts, the carburized Ni clusters served as active sites to generate the active H* species, which then spilled over from the carburized Ni clusters to the FLP sites on CeO 2 supports (Fig. 1 d). The H 2 -temperature programmed reduction (H 2 -TPR) measurements of the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts revealed the enhanced reduction of both Ni-O and Ce-O compared to the reconstructed Ce(OH) 3 /CeO 2 and Ni-CeO 2 catalysts (Figure S18), indicating the high capability of the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts for H 2 activation and the occurrence of hydrogen spillover from the carburized Ni clusters. Then, the H 2 /D 2 kinetic isotope effect (KIE) was further examined to explore the involvement of the hydrogen activation and/or spillover for RWGS (Figure S19). The k H / k D value of Ni-CeO 2 was 1.5 as a result of the zero-point energy difference between isotopic isomers (Fig. 4 c). Comparatively, a significantly higher k H / k D values of 3.8 was observed for the reconstructed Ni-Ce(OH) 3 /CeO 2 (Fig. 4 c), indicating that this process should be accompanied by the formation and dissociation of O-H δ+ bonds on the surface of CeO 2 . 51 , 52 The comparative values of k H / k D directly confirmed the occurrence of hydrogen spillover on the surface of the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts during RWGS. The elimination of the competitive adsorption between CO 2 and H 2 through the carburized Ni clusters would significantly decrease the activation energy of RWGS reaction. Derived from the kinetic experiments (400 ~ 600°C, Note: CO 2 conversions < 20%, Figure S20), these catalysts followed a good linearity between Ln k and 1/ T , and the corresponding slope of the plot yielded the activity energy ( E a , Fig. 4 d). Due to the strong competitive adsorption of CO 2 to H 2 on the FLP sites, the Ce(OH) 3 /CeO 2 catalysts exhibited the highest value of E a (53.7 kJ mol − 1 ), thereby leading to the lowest catalytic activity for RWGS. Although the competitive adsorption was not eliminated, the doped Ni in Ni-CeO 2 enhanced the CO 2 adsorption in comparison to that of the reconstructed Ce(OH) 3 /CeO 2 catalysts with similar oxygen vacancies (Figure S16), as revealed from their CO 2 -temperature programmed desorption (CO 2 -TPD) patterns (Figure S21). Therefore, Ni-CeO 2 delivered a lower E a (48.6 kJ mol − 1 ) for RWGS. For the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts, the competitive adsorption was completely eliminated by introducing the carburized clusters, thereby yielding the lowest E a (41.4 kJ mol − 1 ) for RWGS and achieving exceptional catalytic activity. Carburized Ni clusters for the suppressed methanation The weaken adsorption of CO on both FLPs and C-modified Ni clusters is pivotal for achieving a high selectivity of CO in RWGS. Previous studies have demonstrated that poor CO adsorption on FLPs prevents the over-hydrogenation of CO into CH 4 . 24 DFT results (Fig. 1 c) indicate that the carburization of Ni clusters is anticipated to deliver a low adsorption of CO by regulating the d -band center downwards. Thus, the electronic structure of the carburized Ni clusters was experimentally investigated by the high-resolution valence band (VB) spectroscopy. Compared to the H 2 -treated Ni-Ce(OH) 3 /CeO 2 catalysts, a noticeable displacement of the d -band center for the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts away from VBM revealed a downward shift of the antibonding orbitals and a higher orbital occupancy rate for the carburized Ni clusters (Fig. 4 e). CO-temperature programmed desorption (CO-TPD) directly demonstrated the weaker adsorption of CO on the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts with the carburized Ni clusters compared to that on the H 2 -treated Ni-Ce(OH) 3 /CeO 2 catalysts (Fig. 4 f). Both the carburized Ni clusters through the reaction-driven reconstruction of Ni-Ce(OH) 3 /CeO 2 catalysts and the FLP site with the unique spatial configuration contribute to the weakened CO adsorption on catalyst surface, enabling the high CO selectivity for RWGS. Catalytic pathway of dual-active sites. Finally, in-situ DRIFTS experiments were also conducted to monitor the intermediates involved in the RWGS reaction and explore the catalytic pathway. Initially, a flow of H 2 was introduced to generate the H* species on the surface of the reconstructed Ni-Ce(OH) 3 /CeO 2 , H 2 -treated Ni-Ce(OH) 3 /CeO 2 and Ni-CeO 2 catalysts at 450°C. After 30 min, the H 2 flow was switched to a CO 2 flow at the same temperature. All catalysts exhibited the formate pathway for RWGS, as evidenced by the gradual transformation from bicarbonate intermediates (1600 cm − 1 and 1280 cm − 1 ) to formate intermediates (2845 cm − 1 and 2950 cm − 1 ), and ultimately *CO species (Fig. 5 ). 40 , 53 Notably, due to the adsorption of CO 2 from the FLP sites, no methane (~ 3016 cm − 1 ) was observed on both the reconstructed Ni-Ce(OH) 3 /CeO 2 and Ni-CeO 2 catalysts. However, the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts exhibited significantly lower signals of *HCO 3 species (~ 1600 cm − 1 ) and the stronger signals of *HCOO (~ 2845 cm − 1 ) and *CO (~ 2175 cm − 1 ) species, in comparison with those of Ni-CeO 2 (Fig. 5 a- 5 b). These comparative results suggested the much weaker ability of Ni-CeO 2 with only FLP sites for H 2 dissociation. Subsequently, the CO 2 flow was cut off, and the catalysts were treated in a flow of H 2 /N 2 at 450 ℃ to regenerate the *H species. The disappearance rates of *HCO 3 and *HCOO peaks on the reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts were significantly faster than those on Ni-CeO 2 (Figure S22), further revealing the pivotal roles of the carburized Ni clusters in facilitating H 2 dissociation. The roles of the carburized Ni clusters can be further examined by comparing the in-situ DRIFTS spectra of the reconstructed Ni-Ce(OH) 3 /CeO 2 and H 2 -treated Ni-Ce(OH) 3 /CeO 2 catalysts. Due to the presence of Ni clusters to provide sufficient H* species on their surfaces, these catalysts exhibited obvious characteristic peaks of *CO under the CO 2 flow, indicating the successful hydrogenation of CO 2 . It was noteworthy that the weak interaction between *CO and FLPs resulted in the absence of a characteristic peak of CO* on CeO 2 at ~ 2150 cm − 1 . Subsequently, the desorbed CO molecules from FLP sites could be captured by Ni clusters according to the presence of peaks at 2054 and 2120 cm − 1 (Fig. 5 a and 5 c). However, due to the weak interaction between CO and carburized Ni clusters, the gas phase CO (~ 2175 cm − 1 ) was also observed on reconstructed Ni-Ce(OH) 3 /CeO 2 . Consequently, there was no transformation of the captured *CO into CH 4 , as evidenced by the absence of CH 4 characteristic peaks (~ 3016 cm − 1 , Fig. 5 a). In contrast, due to the strong adsorption of *CO on Ni clusters, the H 2 -treated Ni-Ce(OH) 3 /CeO 2 catalysts exhibited a rapid conversion of *CO intermediates into CH 4 , as evidenced by the clear characteristic CH 4 peaks at 3016 cm − 1 . The in-situ DRIFS experiments also verified the CO 2 hydrogenation occurred on FLP sites. As illustrated in Figure S23, the characteristic peak of Ce 4+ -OH at ~ 3735 cm − 1 (Type I, terminal OH) and ~ 3690 cm − 1 (Type II, bridging OH) significantly decreased along with the presence of Ce 3+ -OH at ~ 3646 cm − 1 . These findings revealed that CO 2 molecule underwent direct reduction, resulting in the retention of one oxygen atom within the FLP sites. After introducing H 2 into the reaction system, the Ce 4+ -OH peak gradually diminished and the Ce 3+ -OH peak reappeared, indicating that the O atom was removed by the spilled H* species for the recovery of the FLP sites. Discussion In summary, the dual-active sites of the carburized Ni clusters and FLP sites have been created through the reaction-driven regioselective reconstruction of the Ni-Ce(OH) 3 /CeO 2 catalysts with the mixed phases of CeO 2 and Ce(OH) 3 . During RWGS, the Ni dopants in the Ce(OH) 3 phase of Ni-Ce(OH) 3 /CeO 2 undergone the reconstruction to create the carburized Ni clusters, while preserving the integrity of FLP sites in the CeO 2 phase. The reconstructed Ni-Ce(OH) 3 /CeO 2 catalysts with the dual-active sites, eliminated the competitive adsorption between H 2 and CO 2 , thereby achieving exceptional performance for the RWGS reaction. The carburized Ni clusters with the downshift of d -band center and FLPs exhibited a weak interaction with CO and thereafter dramatically suppressed the methanation side reaction, realizing satisfactory CO selectivity. This finding provides a successful case of overcoming the incompatibility between the precisely designed active sites and the generation of multiple active sites through a regioselective reconstruction. This specific process opens new avenues for the design of highly performed heterogeneous catalysts. Methods Synthesis of the Ni-Ce(OH) 3 /CeO 2 catalysts Initially, a mixture containing Ce(NO 3 ) 3 (0.8 mmol mL − 1 ) and Ni(NO 3 ) 2 (0.016 mmol mL − 1 ), with a total volume of 5 mL, was introduced into 75 mL of NaOH solution (6.4 mmol mL − 1 ) under continuous stirring at room temperature. After 30 min, this mixture was transferred into a Pyrex bottle (100 mL) for a subsequent hydrothermal process at 100°C for 24 h. Finally, the Ni-Ce(OH) 3 /CeO 2 catalysts were obtained by alternately washing with H 2 O and ethanol for three times and dried overnight at 60 ℃. Catalytic tests of catalysts The RWGS reactions were carried out in a fixed-bed reactor operating at atmospheric pressure. The experimental procedure involved the loading of 50 mg of catalysts into a straight quartz tube, with temperature sensors placed both inside and outside the quartz tube. A H 2 /CO 2 /N 2 mixture gas (8.3 vol. % CO 2 , 25 vol. % H 2 and 66.6 vol. % N 2 ) was introduced into the reactor with a total flow of 60 mL min − 1 . The gas products were analyzed online using a gas chromatography equipped with both TCD and FID detectors. The conversion of CO 2 is calculated as the following: \({\text{Conv}}{{\text{.}}_{{\text{C}}{{\text{O}}_2}}}{\text{(% )=}}\frac{{{{\left[ {{\text{C}}{{\text{O}}_{\text{2}}}} \right]}_{{\text{in}}}} - {{\left[ {{\text{C}}{{\text{O}}_{\text{2}}}} \right]}_{{\text{out}}}}}}{{{{\left[ {{\text{C}}{{\text{O}}_{\text{2}}}} \right]}_{{\text{in}}}}}} \times {\text{100% }}\) The selectivity of CO and CH 4 is calculated as the following: \({S_{{\text{CO}}}}{\text{(% )=}}\frac{{{{\left[ {{\text{CO}}} \right]}_{{\text{out}}}}}}{{{{\left[ {{\text{C}}{{\text{O}}_{\text{2}}}} \right]}_{{\text{in}}}} - {{\left[ {{\text{C}}{{\text{O}}_{\text{2}}}} \right]}_{{\text{out}}}}}} \times {\text{100% }}\) \({S_{{\text{C}}{{\text{H}}_4}}}{\text{(% )=}}\frac{{{{\left[ {{\text{C}}{{\text{H}}_4}} \right]}_{{\text{out}}}}}}{{{{\left[ {{\text{C}}{{\text{O}}_{\text{2}}}} \right]}_{{\text{in}}}} - {{\left[ {{\text{C}}{{\text{O}}_{\text{2}}}} \right]}_{{\text{out}}}}}} \times {\text{100% }}\) The yield of CO is calculated as the following: \(Yiel{d_{{\text{CO}}}}{\text{(% )=Conv}}{{\text{.}}_{{\text{C}}{{\text{O}}_{\text{2}}}}}{\text{(% )}} \cdot {S_{{\text{CO}}}}{\text{(% )}}\) Where CO 2in , CO 2out , CO out and CH 4out represent the moles of CO 2 , CO and CH 4 in the effluent, respectively. The CO generation rates are calculated as the following: \({R_{\text{m}}}_{{{\text{CO}}}}{\text{(mmol}} \cdot {g^{ - 1}} \cdot {h^{ - 1}}{\text{)=}}\frac{{Yiel{d_{CO}} \cdot {V_{C{O_2}}}}}{{{{\text{m}}_{{\text{cat}}}} \cdot {V_m}}}\) Where Yield CO is the yield of CO and m cat is catalyst mass. Data availability The authors declare that the main data supporting the findings of this are available within the article and supplementary information from the corresponding author upon reasonable request. References Li Z et al (2019) Well-defined materials for heterogeneous catalysis: From nanoparticles to isolated single-atom sites. Chem Rev 120:623–682 Schlogl R (2015) Heterogeneous catalysis. Angew Chem Int Ed 54:3465–3520 Chu S, Majumdar A (2012) Opportunities and challenges for a sustainable energy future. Nature 488:294–303 Zhang L, Ren Y, Liu W, Wang A, Zhang T (2018) Single-atom catalyst: a rising star for green synthesis of fine chemicals. 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Science 345:546–550 Additional Declarations There is NO Competing Interest. Supplementary Files Nin1PNCeO2forRWGSreactionSI20241013.docx Supplementary Information Nin1PNCeO2forRWGSreactionSI20241013.docx Cite Share Download PDF Status: Under Review 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5258008","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":381012143,"identity":"381cb703-19ed-433f-9ac6-d65912ee4152","order_by":0,"name":"Yongquan Qu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABC0lEQVRIiWNgGAWjYDADfiA+8ICBgRnM4yFGi2QDUEsCUAsP0VoMDgCJBJhqfFoMjvcefvG2zS7P+Nrhh0BbDrPbSyQwPnjbxiBvjkvLmXNplnPbkovNbqcZALWkMfNIJDAbzm1jMNzZgEPLjRwzY9425sRttxNAWmxAWtikedsYEsBOxa2lPnHz7PQPQC0SIC3svwloMX7M23Y4cYN0DsIWZnxaJM+cMWOcc+544ozbOQUHEgyAfjnzsFlyzjkJww04tPAd7zH+8KasOrF/dvrmDx8qDieztycfBIrYyOOyReEAA5sEIhYMGJIZGBgbgCwJ7OqBQL6BgfkDcsTZ4VQ6CkbBKBgFIxYAAOMiW+NCBql8AAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-6202-1929","institution":"Northwestern Polytechnical University","correspondingAuthor":true,"prefix":"","firstName":"Yongquan","middleName":"","lastName":"Qu","suffix":""},{"id":381012144,"identity":"d6c14fbf-e414-42e1-a249-ddc7f9fc3f70","order_by":1,"name":"Wenbin Li","email":"","orcid":"","institution":"Northwestern Polytechnical University","correspondingAuthor":false,"prefix":"","firstName":"Wenbin","middleName":"","lastName":"Li","suffix":""},{"id":381012145,"identity":"60e3f4a1-aa39-412b-8b11-1e14c060b01e","order_by":2,"name":"Bing Liu","email":"","orcid":"","institution":"Jiangnan University","correspondingAuthor":false,"prefix":"","firstName":"Bing","middleName":"","lastName":"Liu","suffix":""},{"id":381012146,"identity":"9194ec93-951c-4a94-b135-37790834c637","order_by":3,"name":"Qing Guo","email":"","orcid":"","institution":"Northwestern Polytechnical University","correspondingAuthor":false,"prefix":"","firstName":"Qing","middleName":"","lastName":"Guo","suffix":""},{"id":381012147,"identity":"286f164d-429c-4fa6-b1a3-8b50649c7f40","order_by":4,"name":"Wenjie Guo","email":"","orcid":"","institution":"Northwestern Polytechnical University","correspondingAuthor":false,"prefix":"","firstName":"Wenjie","middleName":"","lastName":"Guo","suffix":""},{"id":381012148,"identity":"2a828a3d-15b6-4652-aa1c-152b3e26b272","order_by":5,"name":"Sai Zhang","email":"","orcid":"https://orcid.org/0000-0003-4188-8635","institution":"Northwestern Polytechnical University","correspondingAuthor":false,"prefix":"","firstName":"Sai","middleName":"","lastName":"Zhang","suffix":""}],"badges":[],"createdAt":"2024-10-14 04:40:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5258008/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5258008/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":69794202,"identity":"4a9def09-9c99-4e44-8f91-31b5e81e8500","added_by":"auto","created_at":"2024-11-25 10:07:25","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":7270277,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTheoretical analysis. \u003c/strong\u003e(\u003cstrong\u003ea\u003c/strong\u003e) Scheme of the FLP site on the defective CeO\u003csub\u003e2\u003c/sub\u003e(110) surface. \u003cstrong\u003eNote:\u003c/strong\u003e When two adjacent oxygen vacancies are present on CeO\u003csub\u003e2\u003c/sub\u003e(110), the FLP sites are formed, wherein lattice O\u003csup\u003e2-\u003c/sup\u003e as Lewis bases and two neighboring Ce\u003csup\u003e3+\u003c/sup\u003e ions as Lewis acids. (\u003cstrong\u003eb\u003c/strong\u003e) The adsorption behaviors of CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e on the CeO\u003csub\u003e2\u003c/sub\u003e(110) surface with various active sites. (\u003cstrong\u003ec\u003c/strong\u003e) PDOS analysis of the Ni\u003csub\u003e4\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e(110) and carburized Ni\u003csub\u003e4\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e(110). (\u003cstrong\u003ed\u003c/strong\u003e) Scheme of RWGS on the dual-active sites of the carburized Ni clusters and FLPs.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5258008/v1/1b8f2b80f324641e9bd5ec7e.jpeg"},{"id":69796054,"identity":"610365d0-d9c0-4f6f-957a-1130c6c46968","added_by":"auto","created_at":"2024-11-25 10:15:25","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":4690781,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCatalytic performance of Ni-Ce(OH)\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e/CeO\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e for the RWGS reaction.\u003c/strong\u003e (\u003cstrong\u003ea\u003c/strong\u003e) Scheme of \u003cem\u003ein-situ\u003c/em\u003e regioselective reconstruction of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e to form the dual-active sites of the creatively carburized Ni clusters and precisely designed FLPs. (\u003cstrong\u003eb\u003c/strong\u003e) XRD patterns of the as-synthesized and spent Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts. (\u003cstrong\u003ec\u003c/strong\u003e) High-resolution TEM images of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts. (\u003cstrong\u003ed\u003c/strong\u003e) CO yields of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e, Ni-CeO\u003csub\u003e2\u003c/sub\u003e and Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts for RWGS reaction. (\u003cstrong\u003ee\u003c/strong\u003e) Comparison of the CO generation rates of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts (this work) and other state-of-the-art Ni catalysts through RWGS reaction under similar reaction conditions (see Supplementary Table for more details).\u0026nbsp; (\u003cstrong\u003ef\u003c/strong\u003e) Catalytic stability of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e. \u003cstrong\u003eReaction conditions:\u003c/strong\u003e Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e (50 mg), WHSV (72,000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e), H\u003csub\u003e2\u003c/sub\u003e:CO\u003csub\u003e2\u003c/sub\u003e:N\u003csub\u003e2\u003c/sub\u003e of 3:1:8 and 550 °C.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5258008/v1/0d8a6fb564db09da1fb54c86.jpeg"},{"id":69796713,"identity":"7ef69113-4842-45dd-b60a-a0b0ba0c70a4","added_by":"auto","created_at":"2024-11-25 10:23:25","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":6147888,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eIdentification on \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003ein situ\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e regioselective reconstruction of Ni-doped Ce(OH)\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e/CeO\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e. \u003c/strong\u003e(\u003cstrong\u003ea\u003c/strong\u003e) The CO\u003csub\u003e2\u003c/sub\u003e conversions \u003cem\u003evs.\u003c/em\u003e reaction time for RWGS catalyzed by Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e. (\u003cstrong\u003eb\u003c/strong\u003e) HAADF-STEM and (\u003cstrong\u003ec\u003c/strong\u003e) partially enlarged HAADF-STEM images of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts. (\u003cstrong\u003ed\u003c/strong\u003e) XANES spectra of the Ni-foil, Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e, reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and NiO. (\u003cstrong\u003ee\u003c/strong\u003e) Wavelet-transform plots of the Ni-foil, Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e, reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and NiO by using \u003cem\u003ek\u003c/em\u003e\u003csup\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sup\u003e space. (\u003cstrong\u003ef\u003c/strong\u003e) The \u003cem\u003ek\u003c/em\u003e\u003csup\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sup\u003e weighted Fourier-transformed spectra derived from the EXAFS spectra of the Ni-foil, Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e, reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and NiO. Time-depended SRPES measurements of (\u003cstrong\u003eg\u003c/strong\u003e) Ni \u003cem\u003eL\u003c/em\u003e-edge and (\u003cstrong\u003eh\u003c/strong\u003e) C \u003cem\u003eK\u003c/em\u003e-edge for the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts under Ar treatment. (\u003cstrong\u003ei\u003c/strong\u003e) \u003cem\u003eIn-situ\u003c/em\u003e DRIFTS analysis of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts treated by various gases.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5258008/v1/3fb90553e4dae6d7251d600d.jpeg"},{"id":69794204,"identity":"3bf8acda-fe0a-491d-addc-cb68c2d05b38","added_by":"auto","created_at":"2024-11-25 10:07:25","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":3687223,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKinetic analysis. \u003c/strong\u003eReaction orders of (\u003cstrong\u003ea\u003c/strong\u003e) H\u003csub\u003e2\u003c/sub\u003e and (\u003cstrong\u003eb\u003c/strong\u003e) CO\u003csub\u003e2\u003c/sub\u003e for the RWGS reaction catalyzed by the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e, Ni-CeO\u003csub\u003e2\u003c/sub\u003e and reconstructed Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts. (\u003cstrong\u003ec\u003c/strong\u003e) Isotope effects of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and Ni-CeO\u003csub\u003e2\u003c/sub\u003e for the RWGS reaction. (\u003cstrong\u003ed\u003c/strong\u003e) Ln \u003cem\u003ek\u003c/em\u003e derived from CO generation rates as a function of 1/\u003cem\u003eT\u003c/em\u003e and the derived \u003cem\u003eE\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e values. (\u003cstrong\u003ee\u003c/strong\u003e)\u003cem\u003e d\u003c/em\u003e-band centers of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e-treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts. (\u003cstrong\u003ef\u003c/strong\u003e) CO-TPD for the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e-treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts.\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5258008/v1/88d6453975dc505cd292fa5c.jpeg"},{"id":69796056,"identity":"3100a5ad-3f18-4d5c-8ae0-fa574071a1ff","added_by":"auto","created_at":"2024-11-25 10:15:25","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":7646216,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003eIn situ\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e DRIFTS analysis.\u003c/strong\u003e \u003cem\u003eIn situ\u003c/em\u003e DRIFTS spectra of (\u003cstrong\u003ea\u003c/strong\u003e) reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e, (\u003cstrong\u003eb\u003c/strong\u003e) Ni-CeO\u003csub\u003e2\u003c/sub\u003e and (\u003cstrong\u003ec\u003c/strong\u003e) H\u003csub\u003e2\u003c/sub\u003e-treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e under the flowing of CO\u003csub\u003e2\u003c/sub\u003e. \u003cstrong\u003eNote:\u003c/strong\u003e The catalysts underwent pre-treatment by a flow of 50% H\u003csub\u003e2\u003c/sub\u003e/Ar for 1 h. After removing excess H\u003csub\u003e2\u003c/sub\u003e by an Ar flow, a flow of 50% CO\u003csub\u003e2\u003c/sub\u003e/Ar was introduced. The DRIFTS signals were collected at 450 °C every 20 s during a period of 15 mins.\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5258008/v1/f444ab60b5ce283d46106346.jpeg"},{"id":69797911,"identity":"c245188f-eacf-4548-9c05-a30704eb5e6e","added_by":"auto","created_at":"2024-11-25 10:31:35","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":30402313,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5258008/v1/c8d0fa1d-9a01-4f3e-9f77-69557a8ebe74.pdf"},{"id":69796051,"identity":"81120845-a44a-4d4f-8670-d545d485cfca","added_by":"auto","created_at":"2024-11-25 10:15:25","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":10642751,"visible":true,"origin":"","legend":"Supplementary Information","description":"","filename":"Nin1PNCeO2forRWGSreactionSI20241013.docx","url":"https://assets-eu.researchsquare.com/files/rs-5258008/v1/615dbbaa92e867007a41bb1c.docx"},{"id":69794213,"identity":"dfe4d216-1322-4ec7-9acc-1812a9362b87","added_by":"auto","created_at":"2024-11-25 10:07:25","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":10642751,"visible":true,"origin":"","legend":"","description":"","filename":"Nin1PNCeO2forRWGSreactionSI20241013.docx","url":"https://assets-eu.researchsquare.com/files/rs-5258008/v1/7a93dc8b26d0d16772613bc7.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Reaction-induced regioselective reconstruction of Ni-doped Ce(OH)3/CeO2 enables exceptional activity and selectivity for reverse water-shift reaction","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDevelopment of advanced catalysts to achieve exceptional activity and selectivity is an ambitious but challenging topic for addressing the global challenges of climate, energy security and environmental sustainability.\u003csup\u003e1-3\u003c/sup\u003e Currently, the cutting-edge efforts have been focused on acquiring precisely defined active sites with the meticulously pre-designed geometric and/or electronic structures.\u003csup\u003e4-7\u003c/sup\u003e However, their structures (\u003cem\u003ee.g.\u003c/em\u003e, sizes, phases, local coordination environments) can be significantly affected by the reaction conditions, generally leading to decayed catalytic performance.\u003csup\u003e8,9\u003c/sup\u003e Meanwhile, recent advances have revealed that the reconstruction of catalysts induced by adsorbed species and/or catalytic environments can progressively produce new active sites with the dramatically improved catalytic performance.\u003csup\u003e10-16\u003c/sup\u003e Practically, those reconstructions are challenging to attain through conventional preparation methods. Unfortunately, one irresistibly drawback of the reaction-induced reconstruction strategy is lack of the precise controllability on the pre-designed active sites of catalysts into the anticipated new ones with highly performance.\u003c/p\u003e\n\u003cp\u003eBesides that, since a reaction generally involves multiple reactants, another fundamental paradox arises from the entire surface region of heterogeneous catalysts under the reconstruction in response to the reaction environments, which may be unpropitious to the simultaneous co-adsorption and activation of multiple reactants.\u003csup\u003e17-20\u003c/sup\u003e Motivated by the existential concerns of the reaction-induced reconstruction and encouraged by prior cognitions of the contributions of multiple active sites for co-activation of several molecules on the improved catalytic performance, a novel methodology is anticipated to achieve the precisely controllable and/or regioselective reconstruction of a pre-catalyst under a specific reaction environment. Specifically, this approach can enable \u003cem\u003ein situ\u003c/em\u003e creation of multiple active sites with distinct local environments, facilitating the effective co-activation of all reactants in catalytic reactions.\u003c/p\u003e\n\u003cp\u003eHerein, we demonstrate the reaction-induced regioselective reconstruction of the Ni-doped Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e nanorod (Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e) catalysts to construct the dual-active sites of the creatively carburized Ni clusters and precisely designed frustrated Lewis pairs (FLPs), thereby enabling exceptionally active, selective and robust catalytic performance for reverse water-gas shift (RWGS) reaction. During RWGS, the thermal decomposition of Ce(OH)\u003csub\u003e3\u003c/sub\u003e into CeO\u003csub\u003e2\u003c/sub\u003e triggered the selective aggregation of the Ni dopants into Ni clusters in the region of Ce(OH)\u003csub\u003e3\u003c/sub\u003e, which simultaneously underwent the carbonization by the catalytically generated carbon monoxide (CO) to create new carburized Ni clusters. Additionally, the Ce(OH)\u003csub\u003e3\u003c/sub\u003e-to-CeO\u003csub\u003e2\u003c/sub\u003e phase transition generated more structural defects of oxygen vacancy in the reconstructed Ce(OH)\u003csub\u003e3\u003c/sub\u003e region. Combining the precisely designed defective Ni-doped CeO\u003csub\u003e2\u003c/sub\u003e, these high levels of oxygen vacancies in the regioselective reconstructed catalysts resulted in the formation of abundant FLP sites.\u003csup\u003e21-23\u003c/sup\u003e The synergistic effect of the carburized Ni clusters and FLP sites delivered high capability for the adsorption and activation of H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e, respectively. Simultaneously, the weak CO adsorption on the FLPs and carburized Ni clusters with the downward shift of the \u003cem\u003ed\u003c/em\u003e-band effectively suppressed the methanation side-reaction. Hydrogen spillover from the carburized Ni clusters to the FLP sites enabled a CO generation rate of 27.3 mol g\u003csub\u003eNi\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e with a selectivity of \u0026gt;99.9% for the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts at 550 \u0026deg;C, surpassing those of previous reports by at least one order of magnitude. Moreover, the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts operated stably and continuously for at least 1000 h.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003ch2\u003eTheoretical analysis\u003c/h2\u003e \u003cp\u003eRecently, we have demonstrated both theoretically and experimentally the effective CO\u003csub\u003e2\u003c/sub\u003e activation even at temperatures below 100\u0026deg;C by the constructed FLP sites on the defective CeO\u003csub\u003e2\u003c/sub\u003e(110) surface with two adjacent oxygen vacancies (CeO\u003csub\u003e2\u003c/sub\u003e(110)-2O\u003csub\u003eV\u003c/sub\u003e), consisting of the lattice O\u003csup\u003e2\u0026minus;\u003c/sup\u003e as Lewis base and two neighboring Ce\u003csup\u003e3+\u003c/sup\u003e as Lewis acid (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea).\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e Density functional theory (DFT) calculations reveal the much stronger CO\u003csub\u003e2\u003c/sub\u003e adsorption on FLP(Ce\u003csup\u003e3+\u003c/sup\u003e/Ce\u003csup\u003e3+\u003c/sup\u003e\u0026hellip;O\u003csup\u003e2\u0026minus;\u003c/sup\u003e) through a bridged configuration compared to that on the ideal CeO\u003csub\u003e2\u003c/sub\u003e(110) surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, S1 and S2). Conversely, the relatively weak H\u003csub\u003e2\u003c/sub\u003e adsorption is theoretically profiled on both ideal CeO\u003csub\u003e2\u003c/sub\u003e(110) and FLP sites in comparation to the strong CO\u003csub\u003e2\u003c/sub\u003e adsorption on the same FLP site (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, S1 and S2). Therefore, the competitive adsorption of H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e on the defective CeO\u003csub\u003e2\u003c/sub\u003e(110) indicates the failure of their simultaneous activation, leading to the poor RWGS activity of CeO\u003csub\u003e2\u003c/sub\u003e with FLPs alone in our previous report.\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eRecently, the Ni-doped or Ni-anchored CeO\u003csub\u003e2\u003c/sub\u003e catalysts have been extensively investigated for H\u003csub\u003e2\u003c/sub\u003e dissociation and subsequent CO\u003csub\u003e2\u003c/sub\u003e hydrogenation.\u003csup\u003e\u003cspan additionalcitationids=\"CR26 CR27 CR28\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e To address the impact of Ni, we theoretically investigated the chemical-doping of Ni in CeO\u003csub\u003e2\u003c/sub\u003e by replacing one of Ce\u003csup\u003e3+\u003c/sup\u003e of FLPs or one lattice Ce in the subsurface, as well as examined Ni clusters on CeO\u003csub\u003e2\u003c/sub\u003e surface. As revealed from the DFT calculations (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, S3 and S4), the adsorption energy of CO\u003csub\u003e2\u003c/sub\u003e is still much higher than that of H\u003csub\u003e2\u003c/sub\u003e on the FLP sites of both CeO\u003csub\u003e2\u003c/sub\u003e and Ni-doped CeO\u003csub\u003e2\u003c/sub\u003e. Subsequently, a Ni\u003csub\u003e4\u003c/sub\u003e cluster supported on the surface of CeO\u003csub\u003e2\u003c/sub\u003e(110)-2O\u003csub\u003eV\u003c/sub\u003e (Ni\u003csub\u003e4\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e(110)-2O\u003csub\u003eV\u003c/sub\u003e configuration) is constructed. It is noteworthy that the Ni\u003csub\u003e4\u003c/sub\u003e cluster exhibits a strong dissociative adsorption ability for H\u003csub\u003e2\u003c/sub\u003e (-1.0 eV) in comparison of CO\u003csub\u003e2\u003c/sub\u003e adsorption (-0.64 eV, Figure S5). These findings suggest that H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e molecules can be co-activated on the Ni\u003csub\u003e4\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e(110)-2O\u003csub\u003eV\u003c/sub\u003e system, where the Ni\u003csub\u003e4\u003c/sub\u003e clusters and FLPs act as dual-active sites for the adsorption of H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e, respectively, effectively avoiding their intensely competitive adsorption.\u003c/p\u003e \u003cp\u003eTheoretically, the construction of dual-active sites of Ni clusters and FLP sites on the defective CeO\u003csub\u003e2\u003c/sub\u003e(110) surface holds promise to enable the highly performed RWGS reaction. However, the utilization of Ni nanocatalysts generally induces a significant methanation side reaction.\u003csup\u003e\u003cspan additionalcitationids=\"CR30 CR31\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e Experimental results demonstrated the enhanced RWGS activity of the Ni clusters deposited on PN-CeO\u003csub\u003e2\u003c/sub\u003e (Ni\u003csub\u003ecluster\u003c/sub\u003e/PN-CeO\u003csub\u003e2\u003c/sub\u003e) with FLP sites at the expense of the decreased selectivity of CO and increased selectivity of CH\u003csub\u003e4\u003c/sub\u003e (Figure S6). The methanation side-reaction is attributed to the strong adsorption of CO on Ni clusters and then over-hydrogenation of CO into CH\u003csub\u003e4\u003c/sub\u003e.\u003csup\u003e\u003cspan additionalcitationids=\"CR34 CR35 CR36\" citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e According to the \u003cem\u003ed\u003c/em\u003e-band theory, the binding strength between metal and guest molecules is determined by the filling degree of the antibonding state.\u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e,\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e Introducing carbon atoms into metal clusters can effectively tailor the \u003cem\u003ed\u003c/em\u003e-band center of metals.\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e,\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e Carbon has been demonstrated to be highly miscible in Ni lattice, followed by the surface diffusion and formation of carbide-like phases.\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e Motivated by this recognition, the density of states (DOS) of Ni \u003cem\u003e3d\u003c/em\u003e orbital in both Ni\u003csub\u003e4\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e(110) and carburized Ni\u003csub\u003e4\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e(110) (Note: A carbon atom was introduced into the surface of Ni\u003csub\u003e4\u003c/sub\u003e cluster) were investigated. It was evident that the presence of a carbon atom on the Ni\u003csub\u003e4\u003c/sub\u003e cluster modulates both spin-up and spin-down states, causing a downward shift of the \u003cem\u003ed\u003c/em\u003e-band center of Ni from \u0026minus;\u0026thinsp;1.07 eV to -1.86 eV (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). Consequently, the CO adsorption on the carburized Ni\u003csub\u003e4\u003c/sub\u003e cluster is weakened, as evidenced by the comparison of CO adsorption energy on the carburized Ni\u003csub\u003e4\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e(110) and Ni\u003csub\u003e4\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e(110) surfaces (-1.98 eV \u003cem\u003evs.\u003c/em\u003e -2.13 eV, Figure S7).\u003c/p\u003e \u003cp\u003eBased on the theoretical analysis, the highly performed RWGS reaction can be realized by the rationally designed dual-active sites of the carburized Ni clusters and FLPs on CeO\u003csub\u003e2\u003c/sub\u003e surface, which involves (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed): (\u003cb\u003eI\u003c/b\u003e) the spontaneous dissociation of H\u003csub\u003e2\u003c/sub\u003e molecules on the carburized Ni clusters to generate active H* species; (\u003cb\u003eII\u003c/b\u003e) the efficient activation of CO\u003csub\u003e2\u003c/sub\u003e molecules FLPs and subsequent hydrogenation into CO by the spilled H*; and (\u003cb\u003eIII\u003c/b\u003e) the effectively suppressed the methanation side reaction through weak desorption of CO on both carburized Ni clusters and FLPs. However, the carburized Ni clusters anchored on the surface of CeO\u003csub\u003e2\u003c/sub\u003e with FLP sites is hardly to be synthesized through various conventional methods. Recently, the \u003cem\u003ein situ\u003c/em\u003e reactant/product-induced reconstruction has emerged as a promising avenue to generate new highly efficient carbide-like active sites.\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e Inspired by these findings, it stimulates our efforts to develop a new methodology to synthesize a pre-catalyst, which is capable of facilitating the reaction-induced reconstruction to give the carburized Ni clusters while simultaneously ensuring the precisely designed FLP sites under the catalytic environment of RWGS.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis and characterizations of Ni-doped Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e nanorods\u003c/h2\u003e \u003cp\u003eConsidering the facile synthesis of Ni-doped CeO\u003csub\u003e2\u003c/sub\u003e, the thermally induced Ni aggregation and subsequently reconstituted the carburized Ni clusters might provide an approach to construct the dual-active site during RWGS owing to the high temperature and abundant carbon resources (CO, CO\u003csub\u003e2\u003c/sub\u003e, \u003cem\u003eet. al.\u003c/em\u003e) of the reaction environment. However, the migration of Ni in Ni-doped CeO\u003csub\u003e2\u003c/sub\u003e is highly energy-consuming due to the strong confinement of Ni dopant within CeO\u003csub\u003e2\u003c/sub\u003e lattice, leading to the difficulty to drive the Ni aggregation. To overcome this challenge and achieve the theoretically proposed dual-active sites, herein, the Ni-doped Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e (Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e) pre-catalysts were synthesized through a low-pressure hydrothermal method at 100\u0026deg;C, incorporating varying levels of Ni loading. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, different from the stable Ni-doped CeO\u003csub\u003e2\u003c/sub\u003e, the unstable Ce(OH)\u003csub\u003e3\u003c/sub\u003e component undergoes a regioselective reconstruction into CeO\u003csub\u003e2\u003c/sub\u003e through the thermal decomposition and oxidation during RWGS, accompanied by the formation of Ni clusters, which could \u003cem\u003ein situ\u003c/em\u003e form the carburized Ni clusters by the catalytically generated CO. Importantly, the FLPs sites within the stable CeO\u003csub\u003e2\u003c/sub\u003e component could remain unaffected. On this occasion, the dual-active sites of the creatively carburized Ni clusters and precisely designed FLPs would be came into being through the \u003cem\u003ein situ\u003c/em\u003e regioselective reconstruction of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e pre-catalysts.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePowder X-ray diffraction (XRD) analysis of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e pre-catalysts revealed the formation of a mixed phase of Ce(OH)\u003csub\u003e3\u003c/sub\u003e and CeO\u003csub\u003e2\u003c/sub\u003e with a molar ratio of 0.51:0.49 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). The replacement of relatively larger Ce ions by smaller Ni ions induced a slight shift of the (111) plane of Ce(OH)\u003csub\u003e3\u003c/sub\u003e in comparison with that of Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e (synthesized by the same process without Ni precursor, Figure S8 and S9). Furthermore, transmission electron microscopy (TEM) imaging of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e pre-catalysts did not detect any nickel oxide or metallic nickel species (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec and S10). Notably, the high-resolution TEM image of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e revealed the lattice fringes of 0.30 nm and 0.19 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec), which corresponded to the (101) crystal face of Ce(OH)\u003csub\u003e3\u003c/sub\u003e and (220) crystal face of CeO\u003csub\u003e2\u003c/sub\u003e, respectively.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCatalytic performance of Ni-Ce(OH)/CeO for RWGS\u003c/h3\u003e\n\u003cp\u003eSubsequently, the catalytic performance of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e pre-catalysts with various Ni loadings for RWGS was evaluated in a fixed bed reactor using a feed gas mixture of H\u003csub\u003e2\u003c/sub\u003e:CO\u003csub\u003e2\u003c/sub\u003e (3:1) with a weighted hourly space velocity (WHSV) of 72,000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Their catalytic performances suggested that the optimal Ni content was 0.5 \u003cem\u003ewt.\u003c/em\u003e% (Figure S11). Therefore, Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e mentioned later in this study was referred to the catalysts with a Ni doping of 0.5 \u003cem\u003ewt.\u003c/em\u003e%. To highlight the catalytic performance of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e pre-catalysts, the Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e (Figure S8) and Ni-doped CeO\u003csub\u003e2\u003c/sub\u003e catalysts with Ni loading of 0.5 \u003cem\u003ewt.\u003c/em\u003e% (Ni-CeO\u003csub\u003e2\u003c/sub\u003e, Figure S12) were also prepared.\u003c/p\u003e \u003cp\u003eSpecifically, the Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts with only FLP sites exhibited the lowest CO\u003csub\u003e2\u003c/sub\u003e conversion, which could be attributed to its poor capability for the co-activation of H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e (Figure S13). Introduction of Ni dramatically boosted the catalytic activity of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and Ni-CeO\u003csub\u003e2\u003c/sub\u003e. Notably, the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts exhibited a significantly higher CO\u003csub\u003e2\u003c/sub\u003e conversion than that of Ni-CeO\u003csub\u003e2\u003c/sub\u003e at each reaction temperature. Furthermore, similar to the Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts, high selectivity towards CO (\u0026gt;\u0026thinsp;99.9%) was impressively observed for both Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and Ni-CeO\u003csub\u003e2\u003c/sub\u003e, even at very high conversions of CO\u003csub\u003e2\u003c/sub\u003e (Figure S13). Consequently, with the highest CO\u003csub\u003e2\u003c/sub\u003e conversion and near 100% CO selectivity, the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts undoubtedly achieved the highest CO yield at each temperature (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed).\u003c/p\u003e \u003cp\u003eMore importantly, the CO yield of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e reached 55.0% at 550\u0026deg;C, which closely approached the equilibrium CO yield of 55.1% for RWGS under the operation conditions (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). Consequently, the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts exhibited an exceptionally high CO generation rate of 27.3 mol g\u003csub\u003eNi\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, surpassing the previously reported Ni-based catalysts by at least one order of magnitude with a similar CO selectivity (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef and Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). Although a few catalysts in the literature exhibited a comparable activity in the CO generation rate, their CO selectivity was significantly lower than that of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef and Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). Additionally, the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts delivered remarkable stability for RWGS even at a high temperature of 550\u0026deg;C. The CO yields remained nearly constant and approached the thermodynamic equilibrium yield for at least 1000 h of reaction (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef and S14). Furthermore, each Ni stie achieved an impressively high turnover frequency of \u0026gt;\u0026thinsp;4,500,000.\u003c/p\u003e\n\u003ch3\u003eIdentification of the reaction-driven reconstruction of Ni-Ce(OH)/CeO\u003c/h3\u003e\n\u003cp\u003eConsidering the ease of the Ce(OH)\u003csub\u003e3\u003c/sub\u003e decomposition, the phase of the spent Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts was examined through XRD analysis. The observed phase transformation from the mixed Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e phase into pure CeO\u003csub\u003e2\u003c/sub\u003e strongly suggested the \u003cem\u003ein situ\u003c/em\u003e regioselective reconstruction of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e component within Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e during RWGS (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb and S9). This finding is close alignment with our initial design (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). Consequently, it became imperative to conduct a comprehensive analysis of the evolution of the surface properties of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e under the operation, thereby understanding the reconstruction during RWGS and identifying the key factor for their exceptional catalytic performance in comparison with the Ni-CeO\u003csub\u003e2\u003c/sub\u003e catalysts and other state-of-the-art catalysts (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee).\u003c/p\u003e \u003cp\u003eTo illustrate the occurrence of the reaction-driven reconstruction process, the RWGS reaction was conducted by transferring the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e pre-catalysts at room temperature into the pre-heated reactor at the desired temperatures. An obvious activation period for Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e was experimentally observed as evidenced by their gradually improved CO\u003csub\u003e2\u003c/sub\u003e conversions during the initial 8.5 h at 400\u0026deg;C (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). Notably, the activation periods were significantly shortened from 8.5 h to 1.5 h with the increased reaction temperatures from 400\u0026deg;C to 600\u0026deg;C. This observed activation period unequivocally demonstrated the formation of new active sites through a reaction-driven reconstruction of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e during the RWGS process.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThen, the aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) was employed to examine the structural changes of the catalysts, illustrating the well maintained nanorod structure with the evolution of mesoporous morphology of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). The measured lattice spacing of 0.190 nm also indicated the preservation of (220) crystal face of CeO\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). Importantly, small clusters were observed on the surface of the reconstructed catalysts (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). Moreover, the X-ray photoelectron spectroscopy (XPS) analysis on Ni 2\u003cem\u003ep\u003c/em\u003e orbital electrons revealed the fraction of Ni\u003csup\u003e0\u003c/sup\u003e species from virtually zero in the pre-catalysts to 44.3% in the reconstructed ones, strongly suggesting the occurrence of the reaction-driven reconstruction of the Ni dopant in the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e pre-catalysts into Ni clusters (Figure S15). In contrast, no observed Ni\u003csup\u003e0\u003c/sup\u003e species in the spent Ni-CeO\u003csub\u003e2\u003c/sub\u003e catalysts indicated that the Ni dopants in CeO\u003csub\u003e2\u003c/sub\u003e region did not undergo the reconstruction, confirming the regioselective reconstruction as proposed in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea.\u003c/p\u003e \u003cp\u003eNext, X-ray absorption fine structure (XAFS) spectroscopy was employed to examine the reaction-driven reconstruction of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e. The adsorption edge of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e pre-catalysts exhibited a negative displacement compared to the NiO foil (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed), suggesting the electron transfer from Ce to Ni sites. Comparatively, the electronic structures of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts closely resembled to these of Ni foil, indicating the formation of metallic Ni during RWGS. The EXAFS spectra and wavelet-transform (WT) analysis revealed the presence of Ni-Ni bonds at a distance of 2.18 \u0026Aring; in the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts, consistent with the peak position of Ni-Ni observed in the Ni foil (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef). Notably, the presence of Ni-O bonds was still evident on the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef and Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), indicating the unchanged structure of the doped Ni in the CeO\u003csub\u003e2\u003c/sub\u003e region. Therefore, combining TEM, XRD and XPS results, the XAFS spectra provided crucial evidences to illustrate the reaction-driven reconstruction of the Ni dopants in the specific region of Ce(OH)\u003csub\u003e3\u003c/sub\u003e of the pre-catalysts into Ni clusters.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eStructure parameters of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e derived from the Ni \u003cem\u003eK\u003c/em\u003e-edge EXAFS fitting results.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePaths\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eN\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e (\u0026Aring;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eσ\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e (\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e \u0026Aring;\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eNiO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi-O\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e1.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e5.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi-O\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e6.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eNi-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi-O\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e1.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e11.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi-O\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e10.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eReconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi-O\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e1.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e7.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi-Ni\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e11.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e10.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi-O\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.61\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e10.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNi foil\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi-Ni\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e11.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e5.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eCharacterizations on the carburized Ni clusters\u003c/h3\u003e\n\u003cp\u003eBased on the above comprehensive analysis, the reaction-driven reconstruction of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e created the Ni clusters on CeO\u003csub\u003e2\u003c/sub\u003e surface. Impressively, the reconstructed catalysts exhibited a dramatically high selectivity towards CO, suggesting that the local environments of these reaction-driven reconstructed Ni clusters in Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e were significantly distinct from those of commonly deposited Ni clusters and/or nanoparticles on various supports in previous studies.\u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e,\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e As evidenced by the XPS profile of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts, in addition to the presence of Ni\u003csup\u003e0\u003c/sup\u003e species, a small fraction of nickel carbide was detected at 850.3 eV (Figure S15a). Furthermore, the presence of Ni-C species was also revealed from C \u003cem\u003e1s\u003c/em\u003e spectrum with a peak at 283.8 eV (Figure S15b). Considering the carbon-rich environment conducive to a partial carbonization of metal clusters during RWGS,\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e,\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e the XPS profiles strongly supported the formation of the carburized Ni clusters during the reconstruction process.\u003c/p\u003e \u003cp\u003eThe time-depended synchrotron radiation photoelectron spectroscopy (SRPES) was conducted on the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts to examine the chemical states of the Ni clusters by an Ar plasma etching. As depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg, the Ni \u003cem\u003eL\u003c/em\u003e-edge of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts indicated the co-existence of Ni\u003csup\u003e0\u003c/sup\u003e and Ni\u003csup\u003e2+\u003c/sup\u003e species, again confirming the formation of the Ni clusters. The C species as revealed from C \u003cem\u003eK\u003c/em\u003e-edge gradually diminished with the continuously prolonged Ar plasma treatment, indicating the etching of carbonaceous species (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eh). Furthermore, the significant shift towards the lower binding energy of Ni\u003csup\u003e0\u003c/sup\u003e species was observed as the decrease of C species, indicating a strong interaction between C species and Ni clusters through the electron transfer from Ni to C. Additionally, the higher binding energy of Ni\u003csup\u003e2+\u003c/sup\u003e species suggested the change in coordination from C to O on the CeO\u003csub\u003e2\u003c/sub\u003e surface, accompanied by the etching of C species. Therefore, the SRPES spectra analysis unambiguously demonstrated the environmental-induced reconstruction and carbonization to give the carburized Ni clusters.\u003c/p\u003e \u003cp\u003eAfterwards, \u003cem\u003ein situ\u003c/em\u003e diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was employed under various gaseous environments to investigate how the reconstruction occurred to form the carburized Ni clusters during RWGS. The DRIFTS profile of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e pre-catalysts exhibited a twin adsorption of Ni-(CO)\u003csub\u003e2/3\u003c/sub\u003e on the catalyst surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ei), indicating the atomically dispersed Ni. Following the \u003cem\u003ein situ\u003c/em\u003e treatment of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e with H\u003csub\u003e2\u003c/sub\u003e/CO\u003csub\u003e2\u003c/sub\u003e at 350\u0026deg;C to mimic the catalytic environments, a noticeable reduction in the peak corresponding to Ni-(CO)\u003csub\u003e2/3\u003c/sub\u003e was observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ei). Simultaneously, the emerging peaks at 1930 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1840 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were attributed to the bridged adsorption of CO with three Ni atoms (Ni\u003csub\u003e3\u003c/sub\u003e-CO) and the carbonization Ni species (NiC-CO), respectively.\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e,\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e However, no adsorption of NiC-CO was observed at 1840 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e on the H\u003csub\u003e2\u003c/sub\u003e-treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts. Additionally, the characteristic peaks of NiC-CO were also observed in the CO treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ei). Therefore, these experiments unequivocally demonstrated the crucial roles of the reductive CO for the formation of the carburized Ni clusters.\u003c/p\u003e \u003cp\u003eBased on the aforementioned analysis, the Ni-doped Ce(OH)\u003csub\u003e3\u003c/sub\u003e component underwent the decomposition and oxidation to give CeO\u003csub\u003e2\u003c/sub\u003e as well as the aggregated Ni clusters, which were carbonized into the carburized Ni clusters by CO generated from the catalytic environment of RWGS. Furthermore, XPS data revealed a slight enhancement in oxygen vacancy concentration of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts compared to the pre-catalysts (Figure S16), indicating the preservation of FLP sites.\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e Additionally, both CO\u003csub\u003e2\u003c/sub\u003e conversion and CO selectivity of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts remained nearly unchanged at 550\u0026deg;C for at least 1000 h (Figure S14), indicating the stability of the reaction-driven formation of the carburized Ni clusters and FLPs during RWGS.\u003c/p\u003e\n\u003ch3\u003eCarburized Ni clusters for the elimination of the competitive adsorption\u003c/h3\u003e\n\u003cp\u003eAs proposed from theoretical analysis, the reaction-driven reconstruction of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts during RWGS created the dual-active sites of the carburized Ni clusters and FLP sites, which selectively activated H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e, respectively and thereby significantly mitigated their pronounced co-adsorption and activation on the reconstructed catalyst surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). The experiments for determining the reaction orders of H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e at 300\u0026deg;C and 500\u0026deg;C for various catalysts were performed within the kinetic range to confirm the alleviated competitive adsorption on the constructed dual-active sites (Figure S17). Theoretically, as the reaction order of a reactant increases, its coverage on the catalyst surface is expected to decrease.\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e,\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e In comparison with both the Ni-CeO\u003csub\u003e2\u003c/sub\u003e and reconstructed Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts, the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts exhibited the lowest reaction orders of both H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb), indicating the highest coverage of both H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e on the reconstructed catalyst surface. Therefore, the simultaneous enhancement of H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e coverages revealed their efficient co-adsorption on the surface of the reconstructed catalysts with the dual-active sites of the carburized Ni clusters and FLP sites.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eOn the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts, the carburized Ni clusters served as active sites to generate the active H* species, which then spilled over from the carburized Ni clusters to the FLP sites on CeO\u003csub\u003e2\u003c/sub\u003e supports (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). The H\u003csub\u003e2\u003c/sub\u003e-temperature programmed reduction (H\u003csub\u003e2\u003c/sub\u003e-TPR) measurements of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts revealed the enhanced reduction of both Ni-O and Ce-O compared to the reconstructed Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and Ni-CeO\u003csub\u003e2\u003c/sub\u003e catalysts (Figure S18), indicating the high capability of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts for H\u003csub\u003e2\u003c/sub\u003e activation and the occurrence of hydrogen spillover from the carburized Ni clusters. Then, the H\u003csub\u003e2\u003c/sub\u003e/D\u003csub\u003e2\u003c/sub\u003e kinetic isotope effect (KIE) was further examined to explore the involvement of the hydrogen activation and/or spillover for RWGS (Figure S19). The \u003cem\u003ek\u003c/em\u003e\u003csub\u003e\u003cem\u003eH\u003c/em\u003e\u003c/sub\u003e/\u003cem\u003ek\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e value of Ni-CeO\u003csub\u003e2\u003c/sub\u003e was 1.5 as a result of the zero-point energy difference between isotopic isomers (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec). Comparatively, a significantly higher \u003cem\u003ek\u003c/em\u003e\u003csub\u003e\u003cem\u003eH\u003c/em\u003e\u003c/sub\u003e/\u003cem\u003ek\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e values of 3.8 was observed for the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec), indicating that this process should be accompanied by the formation and dissociation of O-H\u003csup\u003eδ+\u003c/sup\u003e bonds on the surface of CeO\u003csub\u003e2\u003c/sub\u003e.\u003csup\u003e\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e,\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e The comparative values of \u003cem\u003ek\u003c/em\u003e\u003csub\u003e\u003cem\u003eH\u003c/em\u003e\u003c/sub\u003e/\u003cem\u003ek\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e directly confirmed the occurrence of hydrogen spillover on the surface of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts during RWGS.\u003c/p\u003e \u003cp\u003eThe elimination of the competitive adsorption between CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e through the carburized Ni clusters would significantly decrease the activation energy of RWGS reaction. Derived from the kinetic experiments (400\u0026thinsp;~\u0026thinsp;600\u0026deg;C, Note: CO\u003csub\u003e2\u003c/sub\u003e conversions\u0026thinsp;\u0026lt;\u0026thinsp;20%, Figure S20), these catalysts followed a good linearity between Ln \u003cem\u003ek\u003c/em\u003e and 1/\u003cem\u003eT\u003c/em\u003e, and the corresponding slope of the plot yielded the activity energy (\u003cem\u003eE\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed). Due to the strong competitive adsorption of CO\u003csub\u003e2\u003c/sub\u003e to H\u003csub\u003e2\u003c/sub\u003e on the FLP sites, the Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts exhibited the highest value of \u003cem\u003eE\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e (53.7 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), thereby leading to the lowest catalytic activity for RWGS. Although the competitive adsorption was not eliminated, the doped Ni in Ni-CeO\u003csub\u003e2\u003c/sub\u003e enhanced the CO\u003csub\u003e2\u003c/sub\u003e adsorption in comparison to that of the reconstructed Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts with similar oxygen vacancies (Figure S16), as revealed from their CO\u003csub\u003e2\u003c/sub\u003e-temperature programmed desorption (CO\u003csub\u003e2\u003c/sub\u003e-TPD) patterns (Figure S21). Therefore, Ni-CeO\u003csub\u003e2\u003c/sub\u003e delivered a lower \u003cem\u003eE\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e (48.6 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) for RWGS. For the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts, the competitive adsorption was completely eliminated by introducing the carburized clusters, thereby yielding the lowest \u003cem\u003eE\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e (41.4 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) for RWGS and achieving exceptional catalytic activity.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eCarburized Ni clusters for the suppressed methanation\u003c/h2\u003e \u003cp\u003eThe weaken adsorption of CO on both FLPs and C-modified Ni clusters is pivotal for achieving a high selectivity of CO in RWGS. Previous studies have demonstrated that poor CO adsorption on FLPs prevents the over-hydrogenation of CO into CH\u003csub\u003e4\u003c/sub\u003e.\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e DFT results (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec) indicate that the carburization of Ni clusters is anticipated to deliver a low adsorption of CO by regulating the \u003cem\u003ed\u003c/em\u003e-band center downwards. Thus, the electronic structure of the carburized Ni clusters was experimentally investigated by the high-resolution valence band (VB) spectroscopy. Compared to the H\u003csub\u003e2\u003c/sub\u003e-treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts, a noticeable displacement of the \u003cem\u003ed\u003c/em\u003e-band center for the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts away from VBM revealed a downward shift of the antibonding orbitals and a higher orbital occupancy rate for the carburized Ni clusters (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ee). CO-temperature programmed desorption (CO-TPD) directly demonstrated the weaker adsorption of CO on the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts with the carburized Ni clusters compared to that on the H\u003csub\u003e2\u003c/sub\u003e-treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ef). Both the carburized Ni clusters through the reaction-driven reconstruction of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts and the FLP site with the unique spatial configuration contribute to the weakened CO adsorption on catalyst surface, enabling the high CO selectivity for RWGS.\u003c/p\u003e \u003cp\u003e \u003cb\u003eCatalytic pathway of dual-active sites.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eFinally, \u003cem\u003ein-situ\u003c/em\u003e DRIFTS experiments were also conducted to monitor the intermediates involved in the RWGS reaction and explore the catalytic pathway. Initially, a flow of H\u003csub\u003e2\u003c/sub\u003e was introduced to generate the H* species on the surface of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e, H\u003csub\u003e2\u003c/sub\u003e-treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and Ni-CeO\u003csub\u003e2\u003c/sub\u003e catalysts at 450\u0026deg;C. After 30 min, the H\u003csub\u003e2\u003c/sub\u003e flow was switched to a CO\u003csub\u003e2\u003c/sub\u003e flow at the same temperature. All catalysts exhibited the formate pathway for RWGS, as evidenced by the gradual transformation from bicarbonate intermediates (1600 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1280 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) to formate intermediates (2845 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 2950 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), and ultimately *CO species (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e,\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e Notably, due to the adsorption of CO\u003csub\u003e2\u003c/sub\u003e from the FLP sites, no methane (~\u0026thinsp;3016 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) was observed on both the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and Ni-CeO\u003csub\u003e2\u003c/sub\u003e catalysts. However, the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts exhibited significantly lower signals of *HCO\u003csub\u003e3\u003c/sub\u003e species (~\u0026thinsp;1600 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and the stronger signals of *HCOO (~\u0026thinsp;2845 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and *CO (~\u0026thinsp;2175 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) species, in comparison with those of Ni-CeO\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea-\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb). These comparative results suggested the much weaker ability of Ni-CeO\u003csub\u003e2\u003c/sub\u003e with only FLP sites for H\u003csub\u003e2\u003c/sub\u003e dissociation. Subsequently, the CO\u003csub\u003e2\u003c/sub\u003e flow was cut off, and the catalysts were treated in a flow of H\u003csub\u003e2\u003c/sub\u003e/N\u003csub\u003e2\u003c/sub\u003e at 450 ℃ to regenerate the *H species. The disappearance rates of *HCO\u003csub\u003e3\u003c/sub\u003e and *HCOO peaks on the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts were significantly faster than those on Ni-CeO\u003csub\u003e2\u003c/sub\u003e (Figure S22), further revealing the pivotal roles of the carburized Ni clusters in facilitating H\u003csub\u003e2\u003c/sub\u003e dissociation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe roles of the carburized Ni clusters can be further examined by comparing the \u003cem\u003ein-situ\u003c/em\u003e DRIFTS spectra of the reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e-treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts. Due to the presence of Ni clusters to provide sufficient H* species on their surfaces, these catalysts exhibited obvious characteristic peaks of *CO under the CO\u003csub\u003e2\u003c/sub\u003e flow, indicating the successful hydrogenation of CO\u003csub\u003e2\u003c/sub\u003e. It was noteworthy that the weak interaction between *CO and FLPs resulted in the absence of a characteristic peak of CO* on CeO\u003csub\u003e2\u003c/sub\u003e at ~\u0026thinsp;2150 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Subsequently, the desorbed CO molecules from FLP sites could be captured by Ni clusters according to the presence of peaks at 2054 and 2120 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea and \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec). However, due to the weak interaction between CO and carburized Ni clusters, the gas phase CO (~\u0026thinsp;2175 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) was also observed on reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e. Consequently, there was no transformation of the captured *CO into CH\u003csub\u003e4\u003c/sub\u003e, as evidenced by the absence of CH\u003csub\u003e4\u003c/sub\u003e characteristic peaks (~\u0026thinsp;3016 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea). In contrast, due to the strong adsorption of *CO on Ni clusters, the H\u003csub\u003e2\u003c/sub\u003e-treated Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts exhibited a rapid conversion of *CO intermediates into CH\u003csub\u003e4\u003c/sub\u003e, as evidenced by the clear characteristic CH\u003csub\u003e4\u003c/sub\u003e peaks at 3016 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe \u003cem\u003ein-situ\u003c/em\u003e DRIFS experiments also verified the CO\u003csub\u003e2\u003c/sub\u003e hydrogenation occurred on FLP sites. As illustrated in Figure S23, the characteristic peak of Ce\u003csup\u003e4+\u003c/sup\u003e-OH at ~\u0026thinsp;3735 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Type I, terminal OH) and ~\u0026thinsp;3690 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Type II, bridging OH) significantly decreased along with the presence of Ce\u003csup\u003e3+\u003c/sup\u003e-OH at ~\u0026thinsp;3646 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. These findings revealed that CO\u003csub\u003e2\u003c/sub\u003e molecule underwent direct reduction, resulting in the retention of one oxygen atom within the FLP sites. After introducing H\u003csub\u003e2\u003c/sub\u003e into the reaction system, the Ce\u003csup\u003e4+\u003c/sup\u003e-OH peak gradually diminished and the Ce\u003csup\u003e3+\u003c/sup\u003e-OH peak reappeared, indicating that the O atom was removed by the spilled H* species for the recovery of the FLP sites.\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn summary, the dual-active sites of the carburized Ni clusters and FLP sites have been created through the reaction-driven regioselective reconstruction of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts with the mixed phases of CeO\u003csub\u003e2\u003c/sub\u003e and Ce(OH)\u003csub\u003e3\u003c/sub\u003e. During RWGS, the Ni dopants in the Ce(OH)\u003csub\u003e3\u003c/sub\u003e phase of Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e undergone the reconstruction to create the carburized Ni clusters, while preserving the integrity of FLP sites in the CeO\u003csub\u003e2\u003c/sub\u003e phase. The reconstructed Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts with the dual-active sites, eliminated the competitive adsorption between H\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e, thereby achieving exceptional performance for the RWGS reaction. The carburized Ni clusters with the downshift of \u003cem\u003ed\u003c/em\u003e-band center and FLPs exhibited a weak interaction with CO and thereafter dramatically suppressed the methanation side reaction, realizing satisfactory CO selectivity. This finding provides a successful case of overcoming the incompatibility between the precisely designed active sites and the generation of multiple active sites through a regioselective reconstruction. This specific process opens new avenues for the design of highly performed heterogeneous catalysts.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n\u003ch2\u003eSynthesis of the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts\u003c/h2\u003e\n\u003cp\u003eInitially, a mixture containing Ce(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e (0.8 mmol mL\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and Ni(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e (0.016 mmol mL\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), with a total volume of 5 mL, was introduced into 75 mL of NaOH solution (6.4 mmol mL\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) under continuous stirring at room temperature. After 30 min, this mixture was transferred into a Pyrex bottle (100 mL) for a subsequent hydrothermal process at 100\u0026deg;C for 24 h. Finally, the Ni-Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e catalysts were obtained by alternately washing with H\u003csub\u003e2\u003c/sub\u003eO and ethanol for three times and dried overnight at 60 ℃.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n\u003ch2\u003eCatalytic tests of catalysts\u003c/h2\u003e\n\u003cp\u003eThe RWGS reactions were carried out in a fixed-bed reactor operating at atmospheric pressure. The experimental procedure involved the loading of 50 mg of catalysts into a straight quartz tube, with temperature sensors placed both inside and outside the quartz tube. A H\u003csub\u003e2\u003c/sub\u003e/CO\u003csub\u003e2\u003c/sub\u003e/N\u003csub\u003e2\u003c/sub\u003e mixture gas (8.3 \u003cem\u003evol.\u003c/em\u003e% CO\u003csub\u003e2\u003c/sub\u003e, 25 \u003cem\u003evol.\u003c/em\u003e% H\u003csub\u003e2\u003c/sub\u003e and 66.6 \u003cem\u003evol.\u003c/em\u003e% N\u003csub\u003e2\u003c/sub\u003e) was introduced into the reactor with a total flow of 60 mL min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The gas products were analyzed online using a gas chromatography equipped with both TCD and FID detectors.\u003c/p\u003e\n\u003cp\u003eThe conversion of CO\u003csub\u003e2\u003c/sub\u003e is calculated as the following:\u003c/p\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\({\\text{Conv}}{{\\text{.}}_{{\\text{C}}{{\\text{O}}_2}}}{\\text{(% )=}}\\frac{{{{\\left[ {{\\text{C}}{{\\text{O}}_{\\text{2}}}} \\right]}_{{\\text{in}}}} - {{\\left[ {{\\text{C}}{{\\text{O}}_{\\text{2}}}} \\right]}_{{\\text{out}}}}}}{{{{\\left[ {{\\text{C}}{{\\text{O}}_{\\text{2}}}} \\right]}_{{\\text{in}}}}}} \\times {\\text{100% }}\\)\u003c/span\u003e \u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eThe selectivity of CO and CH\u003csub\u003e4\u003c/sub\u003e is calculated as the following:\u003c/p\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\({S_{{\\text{CO}}}}{\\text{(% )=}}\\frac{{{{\\left[ {{\\text{CO}}} \\right]}_{{\\text{out}}}}}}{{{{\\left[ {{\\text{C}}{{\\text{O}}_{\\text{2}}}} \\right]}_{{\\text{in}}}} - {{\\left[ {{\\text{C}}{{\\text{O}}_{\\text{2}}}} \\right]}_{{\\text{out}}}}}} \\times {\\text{100% }}\\)\u003c/span\u003e \u003c/span\u003e\u003c/p\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\({S_{{\\text{C}}{{\\text{H}}_4}}}{\\text{(% )=}}\\frac{{{{\\left[ {{\\text{C}}{{\\text{H}}_4}} \\right]}_{{\\text{out}}}}}}{{{{\\left[ {{\\text{C}}{{\\text{O}}_{\\text{2}}}} \\right]}_{{\\text{in}}}} - {{\\left[ {{\\text{C}}{{\\text{O}}_{\\text{2}}}} \\right]}_{{\\text{out}}}}}} \\times {\\text{100% }}\\)\u003c/span\u003e \u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eThe yield of CO is calculated as the following:\u003c/p\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(Yiel{d_{{\\text{CO}}}}{\\text{(% )=Conv}}{{\\text{.}}_{{\\text{C}}{{\\text{O}}_{\\text{2}}}}}{\\text{(% )}} \\cdot {S_{{\\text{CO}}}}{\\text{(% )}}\\)\u003c/span\u003e \u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eWhere \u003cem\u003eCO\u003c/em\u003e\u003csub\u003e\u003cem\u003e2in\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eCO\u003c/em\u003e\u003csub\u003e\u003cem\u003e2out\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eCO\u003c/em\u003e\u003csub\u003e\u003cem\u003eout\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eCH\u003c/em\u003e\u003csub\u003e\u003cem\u003e4out\u003c/em\u003e\u003c/sub\u003e represent the moles of CO\u003csub\u003e2\u003c/sub\u003e, CO and CH\u003csub\u003e4\u003c/sub\u003e in the effluent, respectively.\u003c/p\u003e\n\u003cp\u003eThe CO generation rates are calculated as the following:\u003c/p\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\({R_{\\text{m}}}_{{{\\text{CO}}}}{\\text{(mmol}} \\cdot {g^{ - 1}} \\cdot {h^{ - 1}}{\\text{)=}}\\frac{{Yiel{d_{CO}} \\cdot {V_{C{O_2}}}}}{{{{\\text{m}}_{{\\text{cat}}}} \\cdot {V_m}}}\\)\u003c/span\u003e \u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eWhere \u003cem\u003eYield\u003c/em\u003e\u003csub\u003e\u003cem\u003eCO\u003c/em\u003e\u003c/sub\u003e is the yield of CO and \u003cem\u003em\u003c/em\u003e\u003csub\u003e\u003cem\u003ecat\u003c/em\u003e\u003c/sub\u003e is catalyst mass.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n\u003ch2\u003eData availability\u003c/h2\u003e\n\u003cp\u003eThe authors declare that the main data supporting the findings of this are available within the article and supplementary information from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLi Z et al (2019) Well-defined materials for heterogeneous catalysis: From nanoparticles to isolated single-atom sites. 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Science 345:546\u0026ndash;550\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-5258008/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5258008/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eReconstruction of catalysts by reaction environments represents a viable approach to create highly performed active sites. Herein, we developed a reaction-induced regioselective reconstruction of Ni-doped Ce(OH)\u003csub\u003e3\u003c/sub\u003e/CeO\u003csub\u003e2\u003c/sub\u003e nanorods to form dual-active sites composed of carburized Ni clusters and frustrated Lewis pairs (FLPs), delivering exceptional activity, selectivity and stability for reverse water-gas shift reaction. Ni aggregation in the Ce(OH)\u003csub\u003e3\u003c/sub\u003e region, coupled with \u003cem\u003ein-situ\u003c/em\u003e carbonization of Ni by catalytically generated CO during reaction, induced the formation of the carburized Ni clusters, which effectively promoted H\u003csub\u003e2\u003c/sub\u003e dissociation. Additionally, Ni doping in the CeO\u003csub\u003e2\u003c/sub\u003e region and Ce(OH)\u003csub\u003e3\u003c/sub\u003e-to-CeO\u003csub\u003e2\u003c/sub\u003e phase transition introduced more oxygen vacancies and thereby generated FLPs in CeO\u003csub\u003e2\u003c/sub\u003e, which facilitated CO\u003csub\u003e2\u003c/sub\u003e adsorption and subsequent hydrogenation by spilled H* species from the carburized Ni clusters. Weak CO adsorption on both the carburized Ni clusters and FLPs significantly suppressed the methanation side-reaction. This reaction-induced regioselective reconstruction strategy provides a new avenue for designing highly performed catalysts.\u003c/p\u003e","manuscriptTitle":"Reaction-induced regioselective reconstruction of Ni-doped Ce(OH)3/CeO2 enables exceptional activity and selectivity for reverse water-shift reaction","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-11-25 10:07:20","doi":"10.21203/rs.3.rs-5258008/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"80dbc966-151d-41f7-9ca0-4d1c16f1ac4e","owner":[],"postedDate":"November 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":40580448,"name":"Physical sciences/Chemistry/Catalysis/Heterogeneous catalysis"},{"id":40580449,"name":"Physical sciences/Chemistry/Green chemistry/Sustainability"}],"tags":[],"updatedAt":"2025-07-30T14:46:39+00:00","versionOfRecord":[],"versionCreatedAt":"2024-11-25 10:07:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5258008","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5258008","identity":"rs-5258008","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}