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

A layered TiO 2 /WO 3 /Pt thin-film has been fabricated on a glass substrate by forming thin-layer TiO 2 on WO 3 with underlying Pt nanoparticles. The over layer (TiO 2 ) and under layer (Pt) at the interface with the WO 3 film act as cocatalysts for photogenerated hole and electron transfer, respectively. As a result, TiO 2 /WO 3 /Pt shows superior photocatalytic activity and superhydrophilicity under visible-light illumination in comparison with WO 3, WO 3 /Pt, and TiO 2 films. Further, the TiO 2 /WO 3 /Pt film shows improved chemical stability under alkaline solution better than the WO 3 film alone, revealing that the TiO 2 layer coated on WO 3 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 WO 3 . Our materials also had the ability to remove surface organic contaminants (stearic acid) under regular indoor lighting like a white fluorescent light bulb.