Metal-Organic Frameworks (MOFs)-Derived Mesoporous Carbon Encapsulated Ultrafine Scandium Oxide Electrocatalyst for Highly Efficient Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid.

Green electrochemical synthesis of 2,5-furandicarboxylic acid (FDCA) from biomass is an essential alternative for the substitution of petroleum-based terephthalic acid. The rational design and application of high-performance electrocatalysts are the key to advance this technique. In this work, mesoporous carbon encapsulated ultrafine Sc₂O₃ nanoparticles are reported as a new, highly efficient and selective electrocatalyst that realizes the concurrent electrochemical oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to FDCA coupled with hydrogen evolution. The performance of the optimum electrocatalyst, Sc₂O₃@C-900, is suppressed its counterparts, including the mesoporous Sc₂O₃ and the state-of the art electrocatalyst, Ni(OH)₂, NiOOH, and some other noble metal electrocatalysts. The high performance is attributed to the ultrafine Sc₂O₃ nanoparticles with abundant oxygen vacancies, and the mesoporous carbon layer synergistically promotes electrochemical oxidation by accelerating the adsorption and confinement of key intermediates for electro-oxidation, and facilitating the transportations of reactants/products within/out of the electrocatalyst. Moreover, experiments including the electrochemical and in situ measurements, as well as theoretical studies, provide insights into the origin of high efficiency and the preference of the diformylfuran (DFF) pathway.