A melamine-assisted pyrolytic synthesis of Ag-CeO2 nanoassemblys for CO oxidation: Activation of Ag-CeO2 interfacial lattice oxygen

Abstract Ag-CeO2 nanoassemblys are prepared with a simple melamine-induced thermal decomposition method. Ag-CeO2 nanoassemblys have a structure composed of Ag nanoparticles and CeO2 nanoparticles. For Ag-CeO2 nanoassemblys, Ag introduction can partially or completely activate lattice oxygen species of CeO2 nanoparticles and however, the ease of Ag-CeO2 interface oxygen activation is strongly influenced by their pyrolysis temperature. Ag-CeO2 nanoassemblys prepared at 350°C have only partial activation of CeO2 surface oxygen. If the calcination temperature increases to 400°C, Ag-CeO2 nanoassemblys are fully activated to form more reducible interfacial lattice oxygen and to promote their low-temperature reductivity. Although excessive calcination temperature (500°C) induces full activation of Ag-CeO2 interface lattice oxygen, Ag-CeO2 nanoassemblys will construct a new Ag-CeO2 interface that is relative difficult to reduce, causing a less amount of reducible interface lattice oxygen provided at higher temperature. Ag-CeO2 nanoassemblys are investigated to reveal the relationship of Ag-CeO2 interfacial oxygen activation and CO catalytic oxidation performance. Ag-CeO2 nanoassemblys with more interfacial lattice oxygen provided at lower temperature are found to have higher catalytic activity than that catalyst with the partially or excessively activated interfacial oxygen. Keynotes: Ag-CeO2 nanoassemblys; Lattice oxygen activation; Surface reconstruction; CO oxidation