Near-Quantitative Electrocatalytic Oxidation of HMF to FDCA over a NiMoCu Heterojunction Catalyst

The conversion of 5-hydroxymethylfurfural (HMF) into the high-value-added product 2,5-furandicarboxylic acid (FDCA) requires efficient and stable electrocatalysts. A three-dimensional porous nanosheet -structured nickel-molybdenum-copper (NiMoCu) ternary catalyst was fabricated on nickel foam via a two-step electrodeposition strategy followed by alkaline heat treatment.Multiple heterointerfaces (MoO₃-CuO/NiOOH) were confirmed to form through the homogeneous integration of Ni, Mo, and Cu elements at the nanoscale, as evidenced by comprehensive characterization (XRD, Raman, TEM, and XPS). Simultaneously, the incorporation of Cu refined the grain size of MoO₃ to 8.2 nm and facilitated the in situ formation of amorphous NiOOH (containing Ni³⁺ species). Moreover, the interfacial electron transfer effect optimized the charge transport pathway, thereby promoting efficient 5-hydroxymethylfurfural oxidation reaction (HMFOR).At1.47 V vs. RHE, the catalyst demonstrated record-breaking performance for HMF electric oxidation, achieving 99% HMF conversion, nearly 100% FDCA selectivity, 98% FDCA yield, and a Faradaic efficiency of 98%. Notably, it retained over 90% of its initial FDCA yield after four consecutive reaction cycles, corresponding to a minimal activity decay of less than 10%.The superior catalytic performance of the NiMoCu ternary catalyst originates from the effective synergy of its three metallic components. Specifically, Ni³⁺ species serve as dynamicactive sites that efficiently drive the reaction, while Mo⁶⁺ species stabilize the Ni³⁺ valence state and accelerate charge migration. Concurrently, the incorporation of Cu selectively suppresses the competing oxygen evolution reaction (OER contribution < 2%). This work presents an effective strategy for designing highly efficient and stable catalysts dedicated to the electrocatalytic conversion of the key biomass platform compound, HMF.