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

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(Td)(2+)in Co(3)O(4)is capable of chemical adsorption for acidic organic molecules, and Co(Oh)(3+)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.