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The strong metal-support interaction (SMSI) has long been studied in heterogonous catalysis on account of its importance in stabilizing active metals and tuning catalytic performance. As a dynamic process taking place at the metal-support interface, the SMSI is closely related to the metal surface properties which are usually affected by the size of metal nanoparticles (NPs). In this work we report the discovery of a size effect on classical SMSI in Au/TiO 2 catalyst where larger Au particles are more prone to be encapsulated than smaller ones. A thermodynamic equilibrium model was established to describe this phenomenon. According to this finding, the catalytic performance of Au/TiO 2 catalyst with uneven size distribution can be improved by selectively encapsulating the large Au NPs in a hydrogenation reaction. This work not only brings in-depth understanding of the SMSI phenomenon and its formation mechanism, but also provides an alternative approach to refine catalyst performance. Strong metal-support interaction (SMSI) is critical in determining the catalytic performance of supported metal catalysts. Here the authors report a phenomenon of size-dependent classical SMSI in Au/TiO 2 catalyst where larger Au particles are more prone to be encapsulated than smaller ones.

Semi-hydrogenation of acetylene in excess ethylene is a key industrial process for ethylene purification. Supported Pd catalysts have attracted most attention due to their superior intrinsic activity but often suffer from low selectivity. Pd single-atom catalysts (SACs) are promising to significantly improve the selectivity, but the activity needs to be improved and the feasible preparation of Pd SACs remains a grand challenge. Here, we report a simple strategy to construct Pd 1 /TiO 2 SACs by selectively encapsulating the co-existed small amount of Pd nanoclusters/nanoparticles based on their different strong metal-support interaction (SMSI) occurrence conditions. In addition, photo-thermo catalysis has been applied to this process where a much-improved catalytic activity was obtained. Detailed characterization combined with DFT calculation suggests that photo-induced electrons transferred from TiO 2 to the adjacent Pd atoms facilitate the activation of acetylene. This work offers an opportunity to develop highly stable Pd SACs for efficient catalytic semi-hydrogenation process. Semi-hydrogenation of acetylene in excess ethylene is a key industrial process for ethylene purification. Here the authors develop highly stable Pd1/TiO2 single-atom catalyst for photo-thermo semi-hydrogenation of acetylene.

Single-atom catalysts (SACs) have demonstrated superior catalytic performance in numerous heterogeneous reactions. However, producing thermally stable SACs, especially in a simple and scalable way, remains a formidable challenge. Here, we report the synthesis of Ru SACs from commercial RuO 2 powders by physical mixing of sub-micron RuO 2 aggregates with a MgAl 1.2 Fe 0.8 O 4 spinel. Atomically dispersed Ru is confirmed by aberration-corrected scanning transmission electron microscopy and X-ray absorption spectroscopy. Detailed studies reveal that the dispersion process does not arise from a gas atom trapping mechanism, but rather from anti-Ostwald ripening promoted by a strong covalent metal-support interaction. This synthetic strategy is simple and amenable to the large-scale manufacture of thermally stable SACs for industrial applications. Large scale production of thermally stable single-atom catalysts (SACs) remains challenging. Here, the authors report scalable synthesis of Ru SACs by heating physical mixture of commercial RuO 2 and Fe-containing support, which is significantly promoted by strong metal-support interaction.

Significant progress has been demonstrated in the development of bifunctional oxide-zeolite catalyst concept to tackle the selectivity challenge in syngas chemistry. Despite general recognition on the importance of defect sites of metal oxides for CO/H 2 activation, the actual structure and catalytic roles are far from being well understood. We demonstrate here that syngas conversion can be steered along a highly active and selective pathway towards light olefins via ketene-acetate (acetyl) intermediates by the surface with coordination unsaturated metal species, oxygen vacancies and zinc vacancies over ZnGaO x spinel−SAPO-34 composites. It gives 75.6% light-olefins selectivity and 49.5% CO conversion. By contrast, spinel−SAPO-34 containing only a small amount of oxygen vacancies and zinc vacancies gives only 14.9% light olefins selectivity at 6.6% CO conversion under the same condition. These findings reveal the importance to tailor the structure of metal oxides with coordination unsaturated metal sites/oxygen vacancies in selectivity control within the oxide-zeolite framework for syngas conversion and being anticipated also for CO 2 hydrogenation. Great progress has been made in the development of bifunctional oxide-zeolite catalysts to tackle the selectivity challenge in syngas chemistry. Here the authors show syngas conversion can be steered along a highly active and selective pathway towards light olefins via ketene acetate (acetyl) intermediates.

Active and stable electrocatalysts for the oxygen evolution reaction are required to produce hydrogen from water using renewable electricity. Here we report that incorporating Mn into the spinel lattice of Co 3 O 4 can extend the catalyst lifetime in acid by two orders of magnitude while maintaining the activity. The activation barrier of the obtained spinel Co 2 MnO 4 is comparable to that of state-of-the-art iridium oxides, most probably due to the ideal binding energies of the oxygen evolution reaction intermediates, as shown using density functional theory calculations. The calculations also show that the thermodynamic landscape of Co 2 MnO 4 suppresses dissolution, which results in a lifetime of over 2 months (1,500 hours) at 200 mA cm −2 geo at pH 1. As the lifetimes of other 3 d metal oxygen evolution catalysts are in the order of days and weeks, despite current densities being lower by an order of magnitude, our results are an important step towards the realization of noble-metal-free water electrolysers. Polymer electrolyte membrane water electrolysis is more efficient than its alkaline counterpart, but its implementation, in part, hinges on developing Earth-abundant catalysts that are active and stable for the oxygen evolution reaction in acid. Now, it is shown that incorporating Mn into Co 3 O 4 substantially extends the catalyst lifetime in acidic electrolyte while maintaining the activity.

Copper-based catalysts for the hydrogenation of CO 2 to methanol have attracted much interest. The complex nature of these catalysts, however, renders the elucidation of their structure–activity properties difficult. Here we report a copper-based catalyst with isolated active copper sites for the hydrogenation of CO 2 to methanol. It is revealed that the single-atom Cu–Zr catalyst with Cu 1 –O 3 units contributes solely to methanol synthesis around 180 °C, while the presence of small copper clusters or nanoparticles with Cu–Cu structural patterns are responsible for forming the CO by-product. Furthermore, the gradual migration of Cu 1 –O 3 units with a quasiplanar structure to the catalyst surface is observed during the catalytic process and accelerates CO 2 hydrogenation. The highly active, isolated copper sites and the distinguishable structural pattern identified here extend the horizon of single-atom catalysts for applications in thermal catalytic CO 2 hydrogenation and could guide the further design of high-performance copper-based catalysts to meet industrial demand. Copper-based catalysts are traditionally very effective for the hydrogenation of CO 2 to methanol, although control over the active site has remained elusive. Here, the authors design a Cu 1 /ZrO 2 single-atom catalyst featuring a Cu 1 –O 3 site responsible for a remarkable performance at 180 °C.

The use of single-atom catalysts is an effective way to reduce the amount of iridium in proton exchange membrane water electrolysis (PEM-WE). However, conventional methods can only obtain surface-loaded single atoms or clusters which cannot meet the needs of high current density and stability. In this study, assisted by lanthanum-doping-induced ion exchange, we realize atomically anchoring iridium within the Co 3 O 4 lattice. The lattice anchored iridium in lanthanum-doped Co 3 O 4 exhibits higher atomic dispersion, a larger average coordination number, and an elevated oxidation state. This improvement stimulates the oxide path mechanism (OPM), resulting in enhanced activity (236 mV at 10 mA cm −2 ) and stability (1000 h at 10 mA cm −2 ). Impressively, our catalyst demonstrates notable performance in a PEM electrolyzer with an iridium mass loading of just 0.2 mg Ir  cm −2 , achieving a low cell voltage of 1.61 V at 1.0 A cm −2 and maintaining stable operation for over 1000 h. This work presents an effective strategy for fabricating low-noble-metal-loading catalysts with enhanced efficiency for PEM-WE. Hydrogen production via proton exchange membrane water electrolysis is limited by the high cost and scarcity of iridium catalysts. By doping lanthanum into cobalt oxide, the authors anchor iridium atoms within the oxide lattice, boosting oxygen evolution activity and stability and reducing iridium loading.

Supported metal (oxide) clusters, with both rich surface sites and high atom utilization efficiency, have shown improved activity and selectivity for many catalytic reactions over nanoparticle and single atom catalysts. Yet, the role of cluster catalysts has been rarely reported in CO 2 electroreduction reaction (CO 2 RR), which is a promising route for converting CO 2 to liquid fuels like formic acid with renewable electricity. Here we develop a bismuth oxide (BiO n ) cluster catalyst for highly efficient CO 2 RR to formate. The BiO n cluster catalyst exhibits excellent activity, selectivity, and stability towards formate production, with a formate Faradaic efficiency of over 90% at a current density up to 500 mA·cm −2 in an alkaline membrane electrode assembly electrolyzer, corresponding to a mass activity as high as 3,750 A·g Bi −1 . The electrolyzer with the BiO n cluster catalyst delivers a remarkable formate production rate of 0.56 mmol·min −1 at a high single-pass CO 2 conversion of 44%. Density functional theory calculations indicate that Bi 4 O 3 cluster is more favorable for stabilizing the HCOO* intermediate than Bi(001) surface and single site BiC 4 motif, rationalizing the improved formate production over the BiO n cluster catalyst. This work highlights the great importance of cluster catalysts in activity and selectivity control in electrocatalytic CO 2 conversion.

Selective hydrogenation of acetylene in excess ethylene is an important reaction in both fundamental study and practical application. Pd-based catalysts with high intrinsic activity are commonly employed, but usually suffer from low selectivity. Pd single-atom catalysts (SACs) usually exhibit outstanding ethylene selectivity due to the weak π-bonding ethylene adsorption. However, the preparation of high-loading and stable Pd SACs is still confronted with a great challenge. In this work, we report a simple strategy to fabricate Pd SACs by means of reducing conventional supported Pd catalysts at suitable temperatures to selectively encapsulate the co-existed Pd nanoparticles (NPs)/clusters. This is based on our new finding that single atoms only manifest strong metal-support interaction (SMSI) at higher reduction temperature than that of NPs/clusters. The derived Pd SACs (Pd 1 /CeO 2 and Pd 1 /α-Fe 2 O 3 ) were applied to acetylene selective hydrogenation, exhibiting much improved ethylene selectivity and high stability. This work offers a promising way to develop stable Pd SACs easily.

Metal-support interaction predominately determines the electronic structure of metal atoms in single-atom catalysts (SACs), largely affecting their catalytic performance. However, directly tuning the metal-support interaction in oxide supported SACs remains challenging. Here, we report a new strategy to subtly regulate the strong covalent metal-support interaction (CMSI) of Pt/CoFe 2 O 4 SACs by a simple water soaking treatment. Detailed studies reveal that the CMSI is weakened by the bonding of H + , generated from water dissociation, onto the interface of Pt-O-Fe, resulting in reduced charge transfer from metal to support and leading to an increase of C-H bond activation in CH 4 combustion by more than 50 folds. This strategy is general and can be extended to other CMSI-existed metal-supported catalysts, providing a powerful tool to modulating the catalytic performance of SACs. A simple water soaking treatment significantly weakened the strong covalent metal-support interaction between the atomically dispersed Pt and CoFe 2 O 4 , which leads to an enhanced activity towards methane combustions by 55 times. This work highlights the critical role of altering the coordination structure of single-atom active sites and provides a new strategy to modulate metal-support interaction regulation.