High-density oxygen-deficient CuO induced from structural reconstruction for efficient furfural oxidation coupled with hydrogen evolution

The electrocatalytic furfural oxidation reaction (FFOR) represents an economical and promising technology to replace conventional oxygen evolution reaction, enabling the co-production of high value chemicals and H₂. Regulating the adsorption of furfural (FF) and OH⁻ species holds paramount importance in enhancing the overall performance. Herein, we have developed a unique CuO catalyst enriched with oxygen vacancies (O_v-CuO) resulting from the electrochemical reconstruction of α-Cu₂S, which demonstrates exceptional FFOR performance, with a conversion of 95.3%, near-perfect selectivity and Faraday efficiency (FE) for furoic acid (FA) at 1.475 V vs. RHE. The study provides detailed comparison of the structural evolution of different sulfide precatalysts and their impact on FFOR. Furthermore, it delves into the structure-activity relationship through a combination of characterization and theoretical calculations. The O_v-CuO not only enhances OH⁻ adsorption, changes the rate-determining step, but also reduces the reaction energy barrier toward FFOR. Additionally, a much lower cell voltage is required to coproduce FA and hydrogen in the two-electrode co-electrolysis system. This work would provide valuable insights into the reaction mechanism of FFOR on Cu based catalysts and establish guidelines for designing defective electrocatalysts for biomass conversion.