Oxygen Vacancy-Rich Bi2WO6-Monolayered Nanosheets Boost Solar-Driven Photocatalytic-Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran

Solar-driven valorization of biomass is increasingly vital in our technologically advancing society. Addressing this need, there is a critical demand for photocatalysts with efficient separation of photocarriers and facile generation of superoxide radicals. Herein, we introduce a two-dimensional monolayer of Bi₂WO₆ characterized by a high density of vacancies that exhibits superior performance in photocatalytic-selective oxidation of 5-hydroxymethylfurfural into 2,5-diformylfuran utilizing solar energy. We have determined through detailed experiments that the photocatalytic efficiency of Bi₂WO₆ is greatly influenced by both the thickness of the nanosheets and their vacancy-rich nature. This is attributed to the unique aspects of 2D materials, which include a larger proportion of surface atoms and extremely rapid charge separation capabilities. In comparative analyses, the monolayer Bi₂WO₆ demonstrates remarkable catalytic efficiency, achieving 57.5% conversion of HMF and 93% selectivity for DFF over 3 h under standard conditions, with a DFF production rate reaching 2404 μmol·g^–1·h^–1. This investigation not only deepens the understanding of the role of defects in photocatalytic materials but also highlights the potential of tuning excitonic properties through defect engineering.