Chemically Stable WO3 Based Thin-Film for Visible-Light Induced Oxidation and Superhydrophilicity

A layered TiO2/WO3/Pt thin-film has been fabricated on a glass substrate by forming thin-layer TiO2 on WO3 with underlying Pt nanoparticles. The over layer (TiO2) and under layer (Pt) at the interface with the WO3 film act as cocatalysts for photogenerated hole and electron transfer, respectively. As a result, TiO2/WO3/Pt shows superior photocatalytic activity and superhydrophilicity under visible-light illumination in comparison with WO3, WO3/Pt, and TiO2 films. Further, the TiO2/WO3/Pt film shows improved chemical stability under alkaline solution better than the WO3 film alone, revealing that the TiO2 layer coated on WO3 plays a dual role; that is, it acts as cocatalyst for better charge separation by hole transfer and serves as a protective layer to improve the chemical stability of WO3. Our materials also had the ability to remove surface organic contaminants (stearic acid) under regular indoor lighting like a white fluorescent light bulb.