Preparation of Au/TiO2 with Metal Cocatalysts Exhibiting Strong Surface Plasmon Resonance Effective for Photoinduced Hydrogen Formation under Irradiation of Visible Light

Abstract

Titanium(IV) oxide (TiO2) having both small platinum (Pt) nanoparticles and large gold (Au) particles without alloying and nanoparticle coagulation was successfully prepared by the combination of traditional photodeposition of Pt in the presence of a hole scavenger (PH) and subsequent Au colloid photodeposition in the presence of a hole scavenger (CPH) onto TiO2–Pt. Au particles having an average diameter of 13 nm were fixed on both TiO2 and TiO2–Pt samples without change in the original size of Au particles, and the Au/TiO2 and Au/TiO2–Pt samples exhibited strong photoabsorption around 550 nm as a result of surface plasmon resonance (SPR) of Au to which the large size of Au particles was attributed. Bare TiO2, TiO2–Pt, Au/TiO2, and Au/TiO2–Pt samples were used for photoinduced hydrogen (H2) formation from 2-propanol in aqueous solutions under irradiation of visible light. The first two samples yielded no H2 because of no response to visible light, but the latter two formed H2, indicating that SPR photoab...