Photocatalytic conversion of 5-hydroxymethylfurfural to 2,5-diformylfuran by S-scheme black phosphorus/CdIn2S4 heterojunction

Abstract

To reduce the dependence on fossil energy, the use of photocatalytic technology value-added conversion of biomass platform molecules has been widely studied. Photocatalytic materials with high photogenerated carrier separation and migration efficiency are key to realizing the molecular value-added conversion of biomass platforms. In this study, a simple and effective method prepared the 2D–3D heterojunction structure of black phosphorus/CdIn₂S₄ for biomass value-added conversion. The use of this catalyst for the photocatalytic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran gave excellent performance under ambient conditions without any additives. Compared with pure CdIn₂S₄, the black phosphorus/CdIn₂S₄ heterojunction has higher photocatalytic selective oxidation activity. The photocatalytic mechanism of S-type heterojunctions with high photogenerated carrier separation and migration efficiency is proposed based on the relevant characterization and DFT simulations. Through a capture agent experiment and electron paramagnetic resonance (EPR) spectroscopy, the main intermediates in the reaction were determined to be holes (h⁺) and the superoxide radical (˙O₂⁻), and the reaction pathway of HMF photocatalytic conversion to DFF was further determined. This paper provides new ideas for S-type heterostructure construction and photocatalytic conversion of biomass platform molecules.