Bifunctional reality of Gd doping to boost the photocatalytic H2O2 production of Au/BiVO4

Abstract

Au/BiVO4 is considered as one of promising composite photocatalytic materials for H2O2 synthesis due to its suitable band structure and exceptional two-electron O2 reduction selectivity. However, the rapid decomposition of H2O2 caused by holes and the slow charge transfer resulting from high Schottky barrier between BiVO4 and Au limit its highly-efficient H2O2 production. In this work, a doping strategy is proposed to solve the above two limitations. Here, as the dopant, Gd is uniformly distributed in BiVO4 crystal, while Au is selectively modified on the electron-rich (010) facets of BiVO4. Consequently, 0.1 wt% Gd-doped Au/BiVO4 photocatalyst is proved to present highest H2O2-production performance with 2.07 mmol/L (AQE = 7.44 %) within 2 h, which is 1.39 times higher than that of Au/BiVO4. The improvement of photocatalytic activity for Au/BiVO4:Gd photocatalyst is mainly attributed to substitution of Gd at Bi-site, which inhibits the decomposition of H2O2, and lowers the Fermi energy level of BiVO4 to match with that of Au, giving rise to fast charge transfer and enhanced two-electron reduction activity of O2. This work provides a new perspective for improving the performance of photocatalyst materials modified by metal cocatalyst.