The Crucial Role of Oxygen Evolution Reaction in Electrocatalytic Oxidative C─C Bond Cleavage in Lignin Biomass...

The electrocatalytic oxidative cleavage of the C─C bond is highly effective for converting lignin biomass into high-value-added aromatic chemicals. However, the oxygen evolution reaction (OER) at applied oxidative potential usually competes in the aqueous environment. In this study, we found that OER does not entirely hinder the cleavage process but rather acts as a synergistic catalytic step. By using defect-rich carbon nanotubes as the electrocatalyst and combining experimental and theoretical analysis, we found that the reactive oxygen species (O₂ ^-) formed before *O₂ desorption serve as the key oxygen source. These species could interact with the enolate intermediate of lignin, which facilitates the in situ production of aromatic compounds. Under the optimal potential of 0.5 V versus Ag/AgCl, 98.8% of 2-phenoxyacetophenone is converted into phenol and benzoic acid via C_α─C_β bond cleavage, with yields of 62.31% and 43.42%, respectively. Additionally, the depolymerization of quasi-natural poplar lignin achieves a total monomer yield of up to 12.41 wt%. This study provides new mechanistic insights into C_α─C_β bond cleavage during electrocatalytic lignin depolymerization under alkaline conditions, contributing to efficient biomass valorization.