Rose-like Bi₂WO₆ Nanostructure for Visible-Light-Assisted Oxidation of Lignocellulose-Derived 5-Hydroxymethylfurfural and Vanillyl Alcohol

Selective production of value-added chemicals using biomass-derived platform chemicals is a sustainable and effective way to fulfil the demands for chemicals around the globe. Photocatalytic biomass conversion is an economical, green, and sustainable process to address the environmental problems caused by the consumption of fossil fuel-derived chemicals and energy sources. In this research work, three Bi-based oxides, Bi2WO6, BiVO4, and Bi2MoO6, are employed as photocatalysts, and their activities are compared in selective oxidation of two important lignocellulose-derived chemicals, 5-hydroxymethylfurfural (HMF) and vanillyl alcohol (VOL). Among these oxides, the rose-like Bi2WO6 nanostructured photocatalyst exhibits the highest catalytic activity and selectively produces 2,5-diformylfuran and vanillin from HMF and VOL. These materials are thoroughly characterized by several techniques (powder X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy) to understand the cause of their different physicochemical properties and photocatalytic activities. N2-sorption measurement, DR-UV–visible analysis, pyridine Fourier transform infrared, and photoelectrochemical measurements indicate a large surface area, an appropriate band gap, high surface acidity, and better migration and separation of the photogenerated charge carriers in Bi2WO6 than in BiVO4 and Bi2MoO6, resulting in higher photocatalytic activity over Bi2WO6. The Bi2WO6 catalyst exhibits excellent activity under an artificial light source (λ > 420) and very good activity under the sunlight. The structure-activity relationship is established using catalytic activity data, physicochemical characterization, and scavenging studies. The scavenging studies suggest that the photogenerated holes (h+), electrons (e–), and superoxide radicals (O2•–) play key roles in achieving high photocatalytic activity. The synthesized photocatalyst exhibits remarkable photostability and recyclability. This research work will motivate researchers and scientists to develop sustainable, cost-effective, and environmentally benign catalytic processes for efficient utilization of sunlight and lignocellulose biomass conversion into energy and value-added chemicals.