Surface reconstruction of self-supporting Ni3S2 electrocatalyst enabling efficient electrooxidation of 5-hydroxymethylfurfural

Electrocatalytic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) offers a sustainable route to synthesize the value-added platform chemical 2,5-furandicarboxylic acid (FDCA). However, the synergistic mechanism of HMF oxidation involving Ni 3 + OOH and the anionic groups generated by the reconstructed nickel-based catalysts remains unclear. Herein, a self-supporting Ni 3 S 2 catalyst is synthesized via a two-step hydrothermal method for efficient HMF oxidation reaction (HMFOR). The synthesized NF/Ni 3 S 2 achieves the current density of 112.50 mA cm −2 at 1.45 V, with 99.59% HMF conversion and 99.18% FDCA yield. In situ Raman spectroscopy and XPS analysis reveal that partial sulfur-containing species are detached from the lattice during the electrochemical reconstruction from S 2− to SO 4 2− . This process generates abundant sulfur vacancies and exposes more nickel active sites, thereby promoting the formation of Ni 3+ OOH species. DFT calculations demonstrate that SO 4 2− incorporation induces charge redistribution in the NiOOH-SO 4 2− system, enhancing the electrophilicity of Ni 3+ sites and reducing the energy barrier across the HMFOR pathway. This work elucidates the synergistic mechanism of SO 4 2− in promoting NiOOH formation and optimizing reaction energetics, providing critical insights for designing advanced sulfide-based electrocatalysts for biomass valorization.