Revealing different depth boron substitution on interfacial charge transfer in TiO2 for enhanced visible-light H2 production

Abstract

Visible-light catalytic H2 production is being actively studied as a promising route to replace fossil fuel and improve the environment. Anion doped TiO2 is a kind of modified semiconductor with great research potential. However, the depth of anion substitution is difficult to control and hence its impact on photo-generated carriers is controversial. In addition, the effect of interfacial anion doping on the deposition behavior of co-catalyst is not clear. Herein, only bulk B-doped TiO2 (OB/TiO2) and surface to bulk B-doped TiO2 (STB/TiO2) were prepared successfully. They exhibited excellent visible-light catalytic H2 production rate, which were 73 times (488.4 μmol/g/h) and 26 times (171.6 μmol/g/h) higher than that of the Blank TiO2 (6.7 μmol/g/h), respectively. By multiple characterizations, directional deposition of Pt induced by electron-deficient structure was observed and photo-generated hole trapping site (Ti4+O2-Ti4+O•-) was identified in subsurface of TiO2. Surface B would accelerate the recombination of photo-generated carriers, and thus render the photocatalytic performance of OB/TiO2 superior to STB/TiO2. This work provides valuable insights for rationally designing anion doped TiO2 and maximizing the photocatalytic efficiency via structural optimizations.