Realizing efficient electrochemical oxidation of 5-hydroxymethylfurfural on a freestanding Ni(OH)2/nickel foam catalyst

With the continuous improvement of solar energy production capacity, how to effectively use the electricity generated by renewable solar energy for electrochemical conversion of biomass is a hot topic. Electrochemical conversion of 5-hydroxymethylfurfural (HMF) to biofuels and value-added oxygenated commodity chemicals provides a promising and alternative pathway to convert renewable electricity into chemicals. Although nickel-based eletrocatalysts are well-known for HMF oxidation, their relatively low intrinsic activity, poor conductivity and stability still limit the potential applications. Here, we report the fabrication of a freestanding nickel-based electrode, in which Ni(OH)₂ species were in-situ constructed on Ni foam (NF) support using a facile acid-corrosion-induced strategy. The Ni(OH)₂/NF electrocatalyst exhibits stable and efficient electrochemical HMF oxidation into 2,5-furandicarboxylic acid (FDCA) with HMF conversion close to 100% with high Faraday efficiency. In-situ formation strategy results in a compact interface between Ni(OH)₂ and NF, which contributes to good conductivity and stability during electrochemical reactions. The superior performance benefits from dynamic cyclic evolution of Ni(OH)₂ to NiOOH, which acts as the reactive species for HMF oxidation to FDCA. A scaled-up device based on a continuous-flow electrolytic cell was also established, giving stable operation with a high FDCA production rate of 27 mg h⁻¹ cm⁻². This job offers a straightforward, economical, and scalable design strategy to design efficient and durable catalysts for electrochemical conversion of valuable chemicals.