Fluoride Ions Post‐Treatment Regulates Interfacial Charge Separation and Transport to Promote Solar Water Splitting of Bismuth Vanadate

Abstract Herein, we propose a simple and effective fluoride (F − ) ions post‐treatment method to improve the solar water splitting performance of monoclinic BiVO 4 (abbreviated as BVO). The surface modification of BVO with functional F − ions not only facilitates the transfer and separation efficiency of carriers at the electrode/electrolyte interface but also promotes the adsorption and activation of water, resulting in a photocurrent of 3.2 mA/cm 2 at a bias voltage of 1.2 V RHE . Furthermore, the transfer and separation of carriers in the bulk and on the surface are further regulated by the oxygen vacancies induced by F − ions, thereby enhancing the PEC water splitting performance of BVO. Notably, the experimental findings demonstrate that the introduce of F − ions into the KBi electrolyte enhances the photo‐charging process of BVO. Specifically, at a bias voltage of 0.6 V RHE , the BVO‐0.12F sample exhibits a stable photocurrent of 1.2 mA/cm 2 , which is twice as high as that of the initial BVO sample. Remarkably, our study unveils that the addition of F − ions into the KBi electrolyte solution plays a pivotal role in facilitating the separation of charge carriers and promoting interfacial charge transport. Consequently, this further leads to a substantial enhancement in the solar water splitting performance for BVO‐0.12F photoanode.