Enhanced oxidative desulfurization of dibenzothiophene under visible light using carbon quantum dot-decorated novel Z-scheme BiVO₄/MOF-808/CN photocatalyst: Mechanism, performance and stability

Background: Photocatalytic oxidative desulfurization technology enabling the facile oxidation of these compounds to sulfones, deep desulfurization, operation at ambient temperature and pressure, and minimal energy consumption. Methods: This study introduces a novel photocatalyst, BiVO₄/MOF-808/CN integrated with carbon quantum dots (BMC-CQD), designed for the oxidative desulfurization of dibenzothiophene (DBT) under visible light irradiation. Significant findings: Novel approach was undertaken by integrating the photocatalyst BiVO₄, g-C₃N₄ with MOF-808 and carbon quantum dots to enhance the interaction between semiconductors. This innovative photocatalyst addresses several limitations associated with MOF-808, including enhanced visible light absorption (2.21–2.60 eV), reduced electron-hole recombination, rapid charge transfer, high surface area (1370 m²/g), large pore volume (0.908 cm³/g). Under optimized conditions of a catalyst dosage of 1.5 g/L, a reaction temperature of 50 °C, an O/S molar ratio of 6, and an initial DBT concentration of 500 mg/L, the 10 %BMC-CQD photocatalyst achieved an impressive 99.5 % DBT removal efficiency in just 25 min. Incorporating CQD into the BMC framework significantly amplifies the removal rate of the DBT by 10.69, 2.13 and 8.7 times compared to the BiVO₄, MOF-808 and CN, respectively. The radical trapping experiments have shown that the ^•OH and ^•O₂⁻ radicals play a key role in the DBT removal process.