NiFe Layered Double Hydroxide-Catalyzed Selective Electrooxidation of 5-HMF to FDCA in a Wide Potential Window

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a promising route for biomass chemical refining, yet its industrial implementation is hindered by limited catalytic activity and a narrow operating potential window. In this study, by optimizing the doping content of Fe in Ni(OH)2, the applicable potential window was expanded by 200 mV compared with that of pristine Ni(OH)2. The optimized Ni1Fe2-LDH catalyst delivered both HMF conversion and FDCA selectivity exceeding 99% across a broad potential range of 1.47–1.67 V vs RHE. Moreover, it demonstrated excellent stability without deactivation after a 24 h continuous electrolysis within the same potential range. Mechanistic investigations through electrochemically active surface area (ECSA) analysis, Tafel slope evaluation, Density Functional Theory (DFT) calculations, and in situ electrochemical impedance spectroscopy (in situ EIS) revealed that Fe doping effectively promotes the formation of Ni3+ active species, which interact favorably with surface-adsorbed oxygen intermediates (e.g., OH*), thereby significantly enhancing the adsorption and activation of HMF molecules. This work provides a viable strategy for developing high-performance electrocatalysts tailored to the requirements of renewable energy-driven industrial HMF electrooxidation processes.