Enhancing visible-light photocatalytic performance of Au/TiO2 catalysts through light reflection-promoted optical absorption with oriented anatase mesocrystals

Au nanoparticles (NPs) attached to various TiO2 supports are widely studied as plasmonic catalysts for driving chemical reactions under visible light irradiation. However, plasmonic catalysis still suffers from unsatisfactory efficiencies due to limited light-harvesting abilities. Here we reported a new tactic to enhance the light-harvesting ability of plasmonic Au NPs by utilizing a light reflection-promoted model - a vertically oriented anatase mesocrystal (meso-TiO2) rooted on Ti foil as the support, and thus achieving efficient photocatalytic sulfur-containing volatile organic compound elimination and hydrogen evolution from water. Experimental evidence and theoretical simulations confirm that the Au NPs in this architecture more effectively harvest visible light because of the simultaneous absorption of both the incident and the back-reflected photons from the meso-TiO2/Ti foil surface, where Ti foil serves as the reflective substrate. The enhanced light absorption of Au NPs in this light reflection-promoted model excited strong localized surface plasmon resonance to yield more reactive species that drive the redox reactions. This research could inspire a new paradigm to improve the photocatalytic performance of plasmonic metals by utilizing the light reflection model.