Heterojunction engineering of Co3S4 to modulate NiO for efficient electrooxidation of 5-hydroxymethylfurfural

The electrooxidation of 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA) serves as an effective means to substitute the kinetically slow anode oxygen evolution reaction (OER) in water electrolysis for hydrogen generation. Nickel-based materials are promising catalysts, but the weak adsorption ability of the active species NiOOH on HMF leads to slow dehydrogenation kinetics, making the rational design of active Ni sites a huge challenge. Herein, a novel heterojunction catalyst (NiO@Co 3 S 4 /NF) with S vacancies is successfully synthesized by interface engineering. Specifically, the construction of the heterostructure optimizes the electronic structure of Ni, which in turn facilitates the generation of NiOOH and enhances its ability to adsorb substrate molecules. S vacancies are beneficial for exposing more active sites and increasing the active surface area. Density functional theory calculations demonstrate that the interfacial electronic redistribution effectively adjusted the d-band center of Ni, and the strong d-p orbital coupling interaction between Ni and HMF can significantly lower the energy barrier of the dehydrogenation step, thereby promoting the highly selective oxidation of HMF to FDCA. Consequently, the NiO@Co 3 S 4 /NF exhibits outstanding electrocatalytic activity, achieving a current density of 50 mA cm −2 at only 1.30 V vs. RHE, with a FDCA yield of 99.62% and a Faradaic efficiency of 99.67%, along with excellent cycling stability. Our work provides new insights into catalyst regulation for biomass upgrading.