Unexpected impact of oxygen vacancies on photoelectrochemical performance of Au@TiO2 photoanodes

Abstract This work investigated the effect of oxygen vacancy (OV) and Au nanoparticles on the photoelectrocatalytic activities of Au@TiO2 photoanodes. The Au@TiO2 films on FTO substrates were prepared by the spin-coating method using emulsions of Au NPs (~4 nm) and TiO2 NPs (~20 nm) dispersing in ethanol. The OV concentration in the TiO2 NPs was controlled by annealing the photoanodes in vacuum and air for different time periods. The absorbance, photoluminescence, and linear sweep voltammetry spectra of the photoanodes were investigated. The experiment results indicated that the increment of the OV concentration enhanced photoelectrocatalytic activity of the TiO2 photoanodes but moderated the activity of the Au@TiO2 photoanodes. These effects were explained based on the Schottky barrier between the Au and TiO2 nanoparticles.