ZnIn₂S₄-Catalyzed Anodic Direct Electrochemical Oxidative Cleavage of C-O Bonds in Alpha-O-4 Linkage in an Aqueous Environment

Electrochemical selective oxidative cleavage of biomass-derived lignin feedstocks, such as C-O bond, into high-value oxygenated fine chemicals and pharmaceutical products offers an emerging route for biomass valorization. Here, we developed an efficient anodic valorization of α-O-4 lignin model compound benzyl phenyl ether (BPE) to the desirable monoaromatics products via the C-O bond direct cleavage at ZnIn 2 S 4 anode under +1.6-2V Ag/AgCl supply. A series of carbon-supported ZnIn 2 S 4 electrodes with different hexagonal and rhombohedral phase distributions were carefully controlled and exhibited over 99% BPE conversion with specific C-O bond selectivity. We then studied substrate competition to compare the electrocatalytic performance of different ZnIn 2 S 4 crystal phases. The experimental results were supported by density functional theory calculations. The substrate scope study revealed the suitability of the R-ZIS induced electrocatalytic system for a variety of substituted lignin α-O-4/β-O-4 model dimers. Overall, this work provides an efficient electrode and approach for enabling atom-efficient electro-refinery of diverse lignin-derived oxygenated chemicals.