¹ O ₂ ‐Mediated Selective Oxidation of 5‐hydroxymethylfurfural to 2,5‐diformylfuran by Ag/Ag ₃ PO ₄ under Visible Light Irradiation

Abstract The synthesis of 2,5‐diformylfuran (DFF) through photocatalytic oxidation of 5‐hydroxymethylfurfural (HMF) is an attractive approach. In this manuscript, a photocatalytic selective oxidation strategy for HMF was developed, using Ag/Ag 3 PO 4 as the photocatalyst and O 2 as the oxidizing agent. The prepared catalyst was characterized systematically by SEM, XRD, XPS, UV‐Vis, PL spectra, and so on. In contrast to previous photocatalytic oxidation strategies for HMF conversion, this catalytic system could efficiently generate 1 O 2 without other reactive oxygen species (ROS) under visible light irradiation. DFF would be obtained with about 90 % selectivity. Moreover, the exclusive formation of 1 O 2 was linked to the more positive conduction band potential (+0.90 eV) of Ag/Ag 3 PO 4 , confirmed by an array of characterization techniques. Additionally, the stability of the catalyst was assessed through cyclic testing and analyses including XRD, and XPS. Nonetheless, this catalytic system could potentially serve as a robust platform for various selective oxidation reactions in the future, due to its exclusive presence of 1 O 2 without the involvement of other ROS.