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

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 H-2 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 asembedded Pt is unreachable to reactants. The A/Pt/R sample shows a photocatalytic H-2 evolution rate as high as 17.9 mmol.g(cat)(-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. (C) 2019 Elsevier Inc. All rights reserved.