Recent advances in electrocatalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid: Mechanism, catalyst, coupling system

Catalytic synthesis of value-added chemicals from sustainable biomass or biomass-derived platform chemicals is an essential strategy for reducing dependency on fossil fuels. As a precursor for the synthesis of important polymers such as polyesters, polyurethanes, and polyamides, FDCA is a monomer with high added value. Meanwhile, due to its widespread use in chemical industry, 2,5-furandicarboxylic acid (FDCA) has gained significant interest in recent years. In this review, we discuss the electrochemical oxidation of 5-hydroxymethylfurfural (HMF) and summarize the most recent advances in electrode materials from the past 5 years, including reaction mechanisms, catalyst structures, and coupling reactions. First, the effect of pH on the electrocatalytic oxidation of furfural is presented, followed by a systematic summary of the reaction mechanism (direct and indirect oxidation). Then, the advantages, disadvantages, and research progress of precious metal, non-precious metal, and non-metallic HMF electrooxidation catalysts are discussed. In addition, a coupled dual system that combines HMF electrooxidation with hydrogen reduction reaction, CO2 reduction, or N-2 reduction for more effective energy utilization is discussed. This review can guide the electrochemical oxidation of furfural and the development of advanced electrocatalyst materials for the implementation and production of renewable resources.