Effect of Ag-CeO2 interface formation during one-spot synthesis of Ag-CeO2 composites to improve their catalytic performance for CO oxidation

Abstract

Ag-CeO2 composites are synthesized by controlling Ag-CeO2 interfacial formation during a wet chemical impregnation or a one-spot thermal decomposition. For Ag-CeO2 composites via a wet chemical impregnation, the introduction of Ag species can change the reductivity of CeO2 nanoparticles and increases oxygen vacancies associated with Ce3+ ions due to the production of Ag-CeO2 interface. Simultaneously, CeO2 nanoparticles grow into larger particles, lowering their specific surface area. Interestingly, the direct introduction of Ag species via a one-spot thermal decomposition induces the simultaneous formation of Ag-CeO2 interface during the formation of CeO2 nanoparticles and greatly improves physicochemical properties of CeO2 nanoparticles. CO oxidation is used to reveal the effect of surface microstructure on catalytic performance of Ag-CeO2 composites. Although CeO2 nanoparticles show higher catalytic activity than CeO2 samples with main [1 1 1] crystal planes due to the exposure of multiple crystal planes with higher reactivity, Ag-CeO2 composites conversely exhibit lower catalytic activity than Ag/CeO2 samples due to the sintering of CeO2 nanoparticles during the wet chemical impregnation. However, Ag-CeO2 composites via one-spot thermal decomposition show higher catalytic activity, indicating that it is feasible to enhance the catalytic performance of Ag-CeO2 composites by tuning the production of Ag-CeO2 interface during their synthesis.