CuO/Co3O4 Bifunctional Catalysts for Electrocatalytic 5-Hydroxymethylfurfural Oxidation Coupled Cathodic Ammonia Production

The electrochemical coupling of biomass oxidation and nitrogen conversion presents a potential strategy for high value-added chemicals and nitrogen cycling. Herein, in this work, CuO/Co3O4 with heterogeneous interface is successfully constructed as a bifunctional catalyst for the electrooxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid and the electroreduction of nitrate to ammonia (NH3). The open-circuit potential spontaneous experiment shows that more 5-hydroxymethylfurfural molecules are adsorbed in the Helmholtz layer of the CuO/Co3O4 composite, which certifies that the CuO/Co3O4 heterostructure is conducive to the kinetic adsorption of 5-hydroxymethylfurfural. In situ electrochemical impedance spectroscopy further shows that CuO/Co3O4 has faster reaction kinetics and lower reaction potential in oxygen evolution reaction and 5-hydroxymethylfurfural electrocatalytic oxidation. Moreover, CuO/Co3O4 also has a good reduction effect on NO3-. The ex-situ Raman spectroscopy shows that under the reduction potential, the metal oxide is reduced, and the generated Cu2O can be used as a new active site for the reaction to promote the electrocatalytic conversion of NO3- to NH3 synthesis. This work provides valuable guidance for the synthesis of value-added chemicals by 5-hydroxymethylfurfural electrocatalytic oxidation coupled with NO3- while efficiently producing NH3.