Efficient cleavage of CO bond of lignin by synergistic electrocatalysis using a polyoxometalate catalyst with bimetallic sites.

This study reported a low-cost and highly efficient Dexter-Silverton polyoxometalate (POM)/Ni foam composite (NiCo-POM/NF) with bimetallic sites for acetophenone production. With this novel composite as an electrocatalyst, β-O-4 in 2-phenoxy-1-phenylethanol (PPE), a typical β-O-4 model, can be selectively oxidized to aromatic chemicals with excellent yields (62 %-74 %) by controlled-potential electrolysis. A PPE conversion of 99.3 % and an acetophenone yield of 36.0 % were achieved from the electrochemical oxidation of PPE at 1.24 V vs. RHE in a deep eutectic solvent (DES). Moreover, real lignin can be effectively cleaved to yield the main products guaiacol and vanillin with the help of the proposed catalyst. In short, the Ni catalyst has excellent catalytic effect on the conversion of the lignin model compound and lignin. The incorporation of Co in POM strengthened adsorption on the substrate and added high-valence active sites, thus significantly improving the oxidation performance of the catalyst. In the bimetallic electrocatalyst with multiple active sites, Co/Co served as an electron transfer mediator (ETM), while the Mo acted as an electron donor for CO oxidative cleavage of PPE. This work provides an effective strategy for catalyst design as well as electrocatalytic valorization of biomass.