Identifying the Geometric Site Dependence of Spinel Oxides for the Electrooxidation of 5‐Hydroxymethylfurfural

Abstract Co‐based spinel oxides, which are of mixing valences with the presence of both Co 2+ and Co 3+ at different atom locations, are considered as promising catalysts for the electrochemical oxidation of 5‐hydroxymethylfurfural (HMF). Identifying the role of each atom site in the electroxidation of HMF is critical to design the advanced electrocatalysts. In this work, we found that Co 2+ Td in Co 3 O 4 is capable of chemical adsorption for acidic organic molecules, and Co 3+ Oh play a decisive role in HMF oxidation. Thereafter, the Cu 2+ was introduced in spinel oxides to enhance the exposure degree of Co 3+ and to boost acidic adsorption and thus to enhance the electrocatalytic activity for HMF electrooxidation significantly.