The effect of the Au loading on the liquid-phase aerobic oxidation of ethanol over Au/TiO2 catalysts prepared by pulsed laser ablation

Abstract

Gold nanoparticles (NPs) synthesized by pulsed laser ablation of a gold target in water were efficiently deposited on TiO2 (P25) without any post-treatment yielding catalysts with Au loadings up to 10wt%. Regardless of the loading, the Au NPs had a mean diameter of 8nm before and after deposition. The ligand-free Au NPs strongly bind to TiO2 surface oxygen vacancies and maintain a homogeneous distribution with loadings up to 4wt%, while a further increase in Au content up to 10wt% results in additional weakly adsorbed Au NPs. The catalytic tests of the Au/TiO2 samples in the selective oxidation of ethanol in the liquid phase identified an optimal loading of 4wt% resulting in the highest yield of acetic acid, which is ascribed to the homogeneous Au distribution and the adequate occupation of surface oxygen vacancies by strongly bound Au NPs without significant Au sintering during reaction.