Cu_xCo_3–xO₄ Spinel Nanofibers for Selective Oxidation of 5-Hydroxymethylfurfural into Fuel Additives

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is considered to be the most promising way to achieve green conversion of biomass resources in industrial production. Herein, a series of CuxCo3–xO4 (0 ≤ x ≤ 1) nanofibers are obtained using an electrospinning method, with discovering the role of Cu/Co interactions in modulating the electronic structure of reaction sites and acidic sites for enhancing the intrinsic activity of HMF electro-oxidation (HMFOR). According to the characterizations and theoretical calculations, the reasonable ratio of Cu/Co affects the structure of active sites and the exposure of Lewis adsorption sites in the spinel and thus finally determines an outstanding catalytic activity. An appropriate amount of Cu occupying the tetrahedral sites in the Co-based spinel promotes significantly the electrocatalytic property; specifically, Cu0.5Co2.5O4 shows the best performance of HMF with a selectivity of 93% and Faraday efficiency of 91% for FDCA. This work offers a strategy to design highly active catalysts by adjusting the metal composition and provides an insight into the modulation of multimetal active site structures at the atomic scale.