A Cu-Modified Bi ₂ WO ₆ /g-C ₃ N ₄ Organic–Inorganic Hybrid Catalyst: Configuration Regulation, Selective Conversion Mechanism, and Pathway Elucidation for Glycerol Valorization to 1,2-Propanediol and 1,3-D

Precise modulation of Cu loading modes to optimize the structural configuration of the catalyst is the core for constructing a highly efficient and stable catalytic system and achieving precise control over selective conversion pathways of glycerol. In this study, a Cu-modified organic–inorganic hybrid catalyst Cu–Bi2WO6/g-C3N4 (CWC) was successfully synthesized. This catalyst exhibits dual selectivity, being capable of selectively oxidizing the secondary hydroxyl groups of glycerol to produce 1,3-dihydroxyacetone (DHA) while selectively reducing the primary hydroxyl groups to yield 1,2-propanediol (1,2-PDO). In addition, superior catalytic efficiency is demonstrated for the formation of 1,2-PDO. Through comprehensive characterization combined with density functional theory (DFT) calculations and X-ray absorption fine structure (XAFS) analysis, a direct correlation was established between the structural configuration of the catalyst and its selectivity, with exposed Cu active sites identified as the key factor promoting the directional conversion of glycerol to 1,2-PDO. Electron spin resonance (ESR) and radical quenching experiments confirmed that the CWC catalyst has an exceptional ability to generate reactive oxygen species (ROS), among which singlet oxygen (1O2) is the core active species driving selective oxidation. Correlative analyses further revealed that the highly exposed Cu configuration significantly enhances product selectivity by strengthening the hydrogenolysis of secondary hydroxyl groups in the glycerol oxidation process. Based on DFT calculation results, a plausible catalytic conversion pathway and unique reaction mechanism are proposed: valence synergy of Cu0/Cu+ promotes efficient charge transfer, synergistic generation of oxygen vacancies and 1O2 enhances selective oxidation/reduction reactions, and Z-scheme heterojunction structure optimizes charge separation efficiency. This study not only elucidates the intrinsic connection between the structural configuration, catalytic pathway, and reaction mechanism of the CWC catalyst but also provides important theoretical support for the design of novel high-efficiency catalysts and selective conversion of glycerol into high-value chemicals.