Bifunctions of a Cr hydroxide layer for water splitting over a platinized Au/TiO2 plasmonic photocatalyst under visible light irradiation

Abstract

Plasmonic water splitting (H2O → H2 + 1/2O2) over a metal-loaded metal oxide under irradiation of a wide range of visible light is an ideal way for H2 production that does not rely on the use of fossil resources. For larger production of H2, cocatalysts having a small hydrogen overpotential such as platinum (Pt) and Rh nanoparticles (NPs) is indispensable; however, these metals induce the back reaction, resulting in low activity for water splitting. In this study, chromium hydroxide (Cr(OH)3) was introduced to gold-titanium(IV) oxide having Pt NPs plasmonic photocatalysts (Au/TiO2-Pt) and the thus-prepared Cr(OH)3/[Au/TiO2-Pt] and related photocatalyst were characterized by using a transmission electron microscope equipped with an energy dispersive X-ray analyzer. Functions of the Cr(OH)3 layer in Cr(OH)3/[Au/TiO2-Pt] were evaluated through photocatalytic reactions under various conditions. The reduction sites of Cr(OH)3/[Au/TiO2-Pt] and the reaction mechanism of water splitting are discussed on the basis of experimental results.