Liquid-phase ethanol oxidation and gas-phase CO oxidation reactions over M doped (M = Ag, Au, Pd, and Ni) and MM′ codoped CeO2 nanoparticles

Abstract

Transition metal doped metal oxides have been studied extensively for potential applications to environments and chemical industry. Herein, M doped (M = Ag, Au, Pd, and Ni) and MM′ codoped CeO2 nanoparticles (NPs) were prepared by a hydrothermal method and their liquid-phase ethanol and gas-phase CO oxidation performances were examined by UV-visible absorption spectroscopy and temperature programmed mass spectrometry, respectively. The ethanol and CO oxidation performances were enhanced greatly by metal-doping and were dependent on the relative concentration of codoped metals. For ethanol oxidation, the concentration of acetaldehyde became saturated at low levels, while that of ethyl acetate continuously increased to become a final major product. For M doped CeO2 NPs, the ethanol oxidation performance showed an order of Ni < Ag < Pd ≪ Au. For MM′ codoped CeO2 NPs, the activity of Au doped CeO2 deteriorated drastically upon adding other metals (Ag, Ni, and Pd) as a cocatalyst.