TiO2/Au/TiO2 plasmonic photocatalyst with enhanced photocatalytic activity and stability under visible-light irradiation

Plasmonic photocatalysis, i.e., photocatalysis with activity under visible-light (vis) irradiation due to plasmonic feature of noble metals (NMs), has been intensively studied as promising method for solar energy conversion. Although various plasmonic photocatalysts have already been investigated, the vis activity is usually low, and thus should be improved for commercial application. Moreover, considering charge carriers’ mechanism, the stability of NMs during long-term irradiation should be also considered. Accordingly, this study has focused on the improvement of photocatalytic activity and stability of gold-modified titania photocatalysts under vis irradiation. Among a few proposed synthesis procedures, modified photodeposition method has resulted in the formation of TiO2/Au/TiO2 composites with high level of photoactivity. Large gold nanoparticles (NPs), formed on large rutile titania particles, are partially covered with fine anatase titania NPs, and thus the interface between titania and gold has been enlarged. Moreover, partial coverage of gold by fine titania NPs hinders gold aggregation, resulting in improved stability of these samples. Action spectrum of 2-propanol oxidation and numerical 3D-FDTD simulations of field distribution have indicated that the enhanced utilization of incident photons is responsible for high activity of TiO2/Au/TiO2 photocatalysts.