Synergetic Nanoarchitectonics of Defects and Cocatalysts in Oxygen-Vacancy-Rich BiVO₄/reduced graphene oxide Mott–Schottky Heterostructures for Photocatalytic Water Oxidation

Water oxidation process is a pivotal step of photosynthesis and stimulates the progress of high-performance catalysts for renewable fuel production. Despite the performance benefit of cocatalysts, defect engineering holds promise to settle inherent limitations of semiconductors aiming at sluggish water oxidation. Here, we modify the in situ growth pathway of monoclinic BiVO4 (m-BiVO4) on reduced graphene oxide (rGO), constructing abundant surface oxygen vacancies (OV)-incorporated m-BiVO4/rGO heterostructure toward water oxidation reaction under visible light. Owing to the OV in the m-BiVO4 component, a vacancy-related defect level allows more electrons to be photoexcited by low-energy photons to cause the electron transition, boosting photoabsorption as well as photoexcitation. Besides, the OV can reinforce surface adsorption and reduce the dissociation energy of water molecules. Particularly because of the synergy of OV and cocatalyst rGO, the OV functions as electron-trapped sites to facilitate the carrier separation; the rGO not only receives electrons from m-BiVO4 promoted by internal electric field over Mott–Schottky heterostructures but also spurs further electron diffusion along a highly conductive carbon network. These merits enable the OV-incorporated m-BiVO4/rGO heterostructure with an over 209% growth in O2 yield relative to the counterpart. The increased performance is also validated by the significant rise of •OH radicals and •O2– radicals. The current work paves a novel avenue for the integration of defect engineering and cocatalyst coupling in artificial photosynthesis.