Enhanced adsorption with hydroxymethyl and aldehyde over the heterophase interface for efficient biomass electrooxidation

Co3O4 has displayed promising ability for 5-hydroxymethylfurfural (HMF) electrooxidation reaction (HMFOR), which is an efficient way to produce high-value chemicals. However, its poor intrinsic ability has seriously limited its electrochemical performance. The introduction of foreign components into Co3O4via heterophase interfacing is an efficient strategy to enhance its intrinsic activity. Herein, we have modified Co3O4 through the fabrication of the heterophase interface between Cu-doped Co3O4 (Cu−Co3O4) and CuO (Cu−Co3O4/CuO). With the introduction of Cu species, the electronic structure of the electrocatalyst has been well-modulated, whose electrons were preferentially transformed from Co to Cu atoms, suggesting a strong electron interaction. The electrochemical results suggest that Cu−Co3O4/CuO exhibited a lower overpotential, faster reaction kinetics, and higher turnover frequency than Cu−Co3O4 and pure Co3O4. Experimental results and theoretical calculations demonstrate that the fabrication of the heterophase interface could have strong adsorption toward HMF owing to the enhanced interaction with the aldehyde and hydroxymethyl groups. Furthermore, Cu−Co3O4/CuO possessed a relatively poor reliance on the furan ring for HMF adsorption but accelerated the oxidation of the aldehyde group. This work provides a significant reference for the development of efficient HMFOR electrocatalysts.