Shifting ultraviolet to visible light of photocatalytic enhancements via Au-nanoparticle decoration of TiO2/WO3 binary coatings

Abstract

A straightforward sputtering/annealing procedure is used to fabricate WO3-loaded anatase-TiO2 (TW) films on solar panel glass. A self-assembled-monolayer (SAM) seeding process that involves soaking an SAM-coated TW film sequentially in the aqueous solutions of SC-1 and HAuCl4–H2O2 is then used to load sub-10-nm-sized Au nanoparticles (NPs) on the TW film, denoted TW@Au. X-ray photoelectron spectroscopy is utilized to establish the relationship between monolayer's structural changes and Au-NP immobilization, as well as the chemical reactions for the formation of the Au NPs. Comparative evaluations of self-cleaning performance reveal that the TW film is inactive to visible light and only responds to ultraviolet light displaying a superhydrophilic surface for 3 months. By contrast, even under cyclic darkroom storage, the TW@Au film generates a durable superhydrophilic surface for half a year toward visible light; it responds strongly to ultraviolet light, holding a superhydrophilic surface for 300 days. The mechanism for the photocatalysis enhancement is elucidated by the surface plasmonic resonance of the Au NPs and the matching of the TiO2/WO3 band structure. The enormous potential of the TW@Au ternary film fully utilizing solar light as a source of self-cleaning glass panel of photovoltaic devices is discussed.