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

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 BiVO 4 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 BiVO 4 NPF photoanode. Additionally, the surface-formed Al 2 O 3 film effectively preserves the stability of photoanode, leading to a substantial improvement in PEC hydrogen evolution of BiVO 4 NPF photoanode in a three-electrode PEC cell with sulfite scavenger. The constructed BiVO 4 /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 BiVO 4 photoanode. Additionally, BiVO 4 /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.