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.