Accelerating Surface Reaction Kinetics and Enhancing Bulk as well as Surface Charge Carrier Dynamics in Al/ Al₂O₃‐Coated BiVO₄ Photoanode

Abstract Photoelectrochemical (PEC) hydrogen evolution from water splitting of semiconductor photoanodes is intricately linked to their light‐absorbing capacity, surface reaction kinetics, bulk charge carrier separation efficiency, and surface charge carrier injection efficiency. Harnessing the surface plasmon resonance effect of metals emerges as a promising approach to enhance PEC performance of semiconductor photoanodes. This work presents the first application of non‐noble metal Al nanoparticles to sensitize a BiVO₄ nanoporous film (NPF) photoanode. This process significantly expedites the surface kinetics of water oxidation, and improves both bulk charge carrier separation and surface carrier injection efficiencies of BiVO₄ NPF photoanode. Additionally, the surface‐formed Al₂O₃ film effectively preserves the stability of photoanode, leading to a substantial improvement in PEC hydrogen evolution of BiVO₄ NPF photoanode in a three‐electrode PEC cell with sulfite scavenger. The constructed BiVO₄/Al NPF heterojunction photoanode exhibits a hydrogen evolution rate of 73.9 µmol cm⁻² h⁻¹ at 1.23 V versus reversible hydrogen electrode, 1.68 times of BiVO₄ photoanode. Additionally, BiVO₄/Al NPF photoanode exhibits excellent stability under long‐time light irradiation of 8 h. This study provides valuable insights into the design of nonnoble‐metal‐based plasmonic photoanodes for efficient hydrogen generation through PEC cell from the perspectives of surface reaction kinetics, charge carrier injection, and separation.