Mechanism on BiVO4 photoanode photoelectrochemical performance improving: Based on surface electrochemical reduction method

In this work, a typical BiVO4 photoanode is employed to explore the performance improving mechanism by surface electrochemical reduction. Corresponding results demonstrate some new information that nanoparticle-like amorphous layer is formed on the surface of BiVO4 and its thickness is positive correlation with the SER force. Furthermore, Scanning Kelvin probe results indicate that the Fermi level of the amorphous layer is shifted positively, inducing a homojunction built-in electric field between the amorphous layer and the bulk BiVO4. The transfer ability of photogenerated holes from the bulk to the surface of photoanode can enhance obviously. In addition, due to the quasi-oxygen vacancy defects in the amorphous layer, the enhanced hydrophilicity improves the PEC performance synergistically. However, as the thickness of amorphous layer increasing, it raises the migration time and secondary recombination rate of the photogenerated carriers. Therefore, a controllable amorphous surface and PEC performance of BiVO4 photoanode can realize by adjusting the SER force.