Carbon-vacancy engineering approach to g-C3N4 for selective 5-hydroxymethylfurfural oxidation coupled with H2O2 production

Photocatalytic H2O2 production and selective oxidation of 5-hydroxymethylfurfural (HMF) occur in synergy, which improves the utilization of photogenerated carriers. In this paper, g-C3N4 (CN) under defect engineering was used in the photocatalytic production of H2O2 and HMF oxidation. It was found that H2O2 productivity has the order of Cv-CN (283.9 mu mol g(-1) h(-1)) > Nv-CN (241.4 mu mol g(-1) h(-1)) > CN (154.0 mu mol g(-1) h(-1)), the DFF yield correlates positively with the above order, and that of Cv-CN reached as high as 50.7 mu mol L-1. The yield of H2O2 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 H2O2 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 H2O2 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 H2O2 and selective oxidation of HMF.

Automated summary

Photocatalytic H2O2 production and selective oxidation of 5-hydroxymethylfurfural (HMF) were achieved using defect-engineered g-C3N4 (CN) catalyst. It was found that Cv-CN exhibited higher H2O2 productivity and DFF yield, as well as better charge separation efficiency. This study provides a feasible and practical bifunctional photocatalytic system for sustainable and green development.