More efficiently enhancing photocatalytic activity by embedding Pt within anatase–rutile TiO2 heterophase junction than exposing Pt on the outside surface

Abstract

Loading noble metal on the surface has been widely used to improve photocatalytic activity of semiconductor photocatalyst. Here, Pt-embedded anatase (A)-rutile (R) TiO2 junction photocatalyst (A/Pt/R) was found to show much more efficient photocatalytic H2 evolution activity than the other TiO2 photocatalysts loading Pt on the outside surface (such as Pt/A/R, Pt/A, Pt/R and Pt/P25), although the as-embedded Pt is unreachable to reactants. The A/Pt/R sample shows a photocatalytic H2 evolution rate as high as 17.9 mmol⋅gcat−1⋅h−1, which is 27.2 and 2.5 times higher than the common A/R and Pt/A/R samples, respectively. The traditional theory fails to explain the unexpected high photoactivity. The reverse tandem Schottky junction is suggested to be possibly responsible for the high photoactivity of A/Pt/R, which allows the photogenerated electrons to transfer more swimmingly from rutile to anatase than the common A/R phasejunction. This finding provides a new strategy for further promoting photocatalytic activity of Pt/TiO2 and other heterophase or heterojunction photocatalysts.