Modulating Ni-S coordination in NiS to promote electrocatalytic oxidation of 5-hydroxymethylfurfural at ampere-level current density.

Electricity-driven oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a highly attractive strategy for biomass transformation. However, achieving industrial-grade current densities remains a great challenge. Herein, by modulating the water content in a solvothermal system, NiS/NF with stabilized and shorter Ni-S bonds as well as a tunable coordination environment of Ni sites was fabricated. The prepared NiS/NF was highly efficient for electrocatalytic oxidation of HMF to produce FDCA, and the FDCA yield and Faraday efficiency could reach 98.8% and 97.6% at the HMF complete conversion. More importantly, an industrial-grade current density of 1000 mA cm could be achieved at a potential of only 1.45 V RHE for HMFOR and the current density could exceed 500 mA cm with other bio-based compounds as the reactants. The excellent performance of NiS/NF originated from the shorter Ni-S bonds and its better electrochemical properties, which significantly promoted the dehydrogenation step of oxidizing HMF. Besides, the gram-scale FDCA production could be realized on NiS/NF in a MEA reactor. This work provides a robust electrocatalyst with high potential for practical applications for the electrocatalytic oxidation of biomass-derived compounds.