Tuning the Dynamic Interfacial Structure of Copper-Ceria Catalysts by Indium Oxide during CO Oxidation

The substitution of base-metal oxides for noble metals is a great challenge for catalysts, sensors, and other functional materials. In this work, the dynamic structure at the interface of binary metal oxides, as a popular natural phenomenon in material science and catalysis, was studied in detail in the case of a binary copper ceria species (CuOx-CeO2). The catalytic activity of CuOx-CeO2 could be largely improved by doping indium oxide (In2O3). The reaction rate of 1.26 X 10(-5) molco s(-1) for a 1.25In5Cu/CeO2 catalyst toward CO oxidation is 12 times higher than that from commercial Pd catalysts. In addition, the indium doped catalyst shows strong resistance to CO2 and H2O poisoning. We determined the dynamic interfacial structure of CuOx/CeO2 catalysts induced by In2O3 during CO oxidation using in situ techniques, intrinsic kinetics, and density functional theory calculations (DFT). Indeed, the surface of CuOx particles could be reconstructed through the interaction with In2O3. Such an interaction not only helps to generate more active sites at interfaces between CuOx and CeO2 but also lowers the CO adsorption strength and reduces the accumulation of surface carbonates. Meanwhile, In2O3 could also modify the electronic structure to improve the reducibility of CuOx, thus shifting the redox equilibrium of Cu2+ + Ce3+ <-> Cu+ + Ce4+ to create Cu+ or Cu-0 species at the interfacial sites. This study not only reveals the dynamic interfacial structure of metal oxide catalysts but also demonstrates a feasible way to fine-tune the interfacial structure of binary metal oxides.