Efficient photoelectrocatalytic performances with WO3/BiVO4 heterojunction photoanode: applied bias-promoted photoinduced charge transfer and separation†

Abstract

Combining tungsten trioxide (WO3) with bismuth vanadate (BiVO4) to form heterojunction photoanode is a promising solution to achieving highly efficient photoelectrocatalytic (PEC) performances. In this work, we successfully fabricated the WO3/BiVO4 heterojunction on a tungsten (W) foil in a hydrothermal route, followed by a successive ionic layer adsorption and reaction (SILAR) process. The PEC performances for synergetic H2 evolution and organic pollutant degradation were significantly enhanced after the BiVO4 nanoparticles were loaded on the WO3 photoanode. The PEC performance with WO3/BiVO4 heterojunction as photoanode was demonstrated to be much more dependent on applied bias potential (Vab) than that with pristine WO3 as photoanode. Based on the various photoelectrochemical features and fundamental theory of semiconductor heterojunction, it was well elucidated that, under the applied bias potential, the gradual diminishment and eventual reversal of the energy band bending at the heterojunction interface achieve the efficient transfer and separation of more photogenerated charges, thereby enhancing the overall PEC performances. This work highlights the roles of the evolution of the band bending in WO3/BiVO4 heterojunction interface by applied bias in promoting the efficient transfer and separation of the photogenerated charges.