Cation Exchange-Induced Nickel Active Sites on FeOOH Cocatalyst for Enhanced Photoelectrochemical Water Oxidation of BiVO4 Photoanode

Developing highly efficient and stable BiVO4 photoanodes facilitates high-efficiency Photoelectrochemical (PEC) water splitting, offering a promising pathway for converting solar energy into hydrogen energy. Our study focuses on the rational loading and modification of photoanodic cocatalysts to address the inherent limitations of pristine BiVO4. Specifically, Ni active sites were introduced onto the surface via a vapour-phase cation substitution strategy following the photo-assisted electrodeposition of uniformly loaded FeOOH. The substituted Ni:FeOOH /BiVO4 photoanode achieves a significantly enhanced carrier injection efficiency of 94.5% at 1.23 VRHE, with photocurrent density rising from 1.4 mA·cm-2 to 5.7 mA·cm-2, approximately quadrupling the original photoanode’s performance. The Ni substitution of FeOOH overcomes the traditional performance limitations of BiVO4 by simultaneously enhancing catalytic activity and charge transport kinetics. Consequently, this precise construction of active sites and the synergistic design of charge transport channels substantially improve the intrinsic activity of the oxygen evolution reaction (OER), providing a versatile and novel strategy for developing highly efficient and stable photoanodes.