Promoting Photoelectrochemical Activity and Stability of WO₃/BiVO₄Heterojunctions by Coating a Tannin Nickel Iron Complex

Achieving enhanced photoelectrochemical (PEC) activity and stability of a photoanode remains as a formidable challenge. In this study, a porous tannin nickel iron complex coated WO3/BiVO4 heterojunction (WO3/BiVO4@TANiFe) is constructed to achieve enhanced PEC activity and stability. The in situ construction of a type-II heterostructure is highly beneficial for broad visible light utilization and efficient separation of photogenerated carriers. In addition, the intact coating of ultrathin tannin nickel iron nanolayer could not only accelerate the reaction kinetics of water oxidation but also safeguard the semiconductors from photocorrosion during the PEC reaction. As a result, the as-designed WO3/BiVO4@TANiFe ternary photoelectrode exhibits an outstanding photocurrent density of 3.7 mA cm-2 at 1.23 V vs RHE with substantially enhanced running durability at high photocurrent density. The present study would provide a rational route for developing highly active and stable photoanodes for solar-energy conversion applications.