Carbon-vacancy engineering approach to g-CN for selective 5-hydroxymethylfurfural oxidation coupled with HO production

Photocatalytic H 2 O 2 production and selective oxidation of 5-hydroxymethylfurfural (HMF) occur in synergy, which improves the utilization of photogenerated carriers. In this paper, g-C 3 N 4 (CN) under defect engineering was used in the photocatalytic production of H 2 O 2 and HMF oxidation. It was found that H 2 O 2 productivity has the order of Cv-CN (283.9 μmol g −1 h −1 ) > Nv-CN (241.4 μmol g −1 h −1 ) > CN (154.0 μmol g −1 h −1 ), the DFF yield correlates positively with the above order, and that of Cv-CN reached as high as 50.7 μmol L −1 . The yield of H 2 O 2 and 2,5-dicarbonylfuran (DFF) was increased by 1.7 times and 6.3 times compared with the original CN, respectively. The lowest PL intensity and longest fluorescence lifetime indicate higher charge separation efficiency of Cv-CN. DFT calculations show that the electron-hole separation on Cv-CN is better compared to CN and the formation of H 2 O 2 on Cv-CN has a lower energy barrier, which will be beneficial for the adsorption/activation of O 2 . Selective oxidation of HMF to DFF using noble metal-free catalysts under mild reaction conditions combined with H 2 O 2 production can both reduce the electron/hole complexation rate and increase the added value of the reaction. This designed bifunctional photocatalytic system may be more feasible and practical from a sustainable and green development perspective. This work also thus provides a new method/material for photocatalytic production of H 2 O 2 and selective oxidation of HMF. CN modified with carbon and nitrogen vacancies was obtained through calcination under different atmospheres, resulting in efficient visible-light-driven photocatalysts for the conversion of biomass-relevant alcohols into fine chemicals.