Engineering Ni-O-Co electron transfer bridges on Co-Ni₃S₂ interface for boosting electrocatalytic...

Electrocatalytic 5-hydroxymethylfurfural oxidation (HMFOR) represents a green and efficient approach to substitute the sluggish oxygen evolution reaction (OER), with its products exhibiting high added value. Nevertheless, the design of highly efficient catalysts for HMFOR and the elucidation of their catalytic mechanisms remain significant challenges. Herein, inspired by the concept of p-d orbitals coupling between metals and nonmetals, the Co-Ni₃S₂/NF heterojunction was constructed. This catalyst demonstrated superior electrocatalytic activity for HMFOR, achieving nearly 100 % conversion of 5-hydroxymethylfurfural (HMF), along with highly selectivity for 2,5-furandicarboxylic acid (FDCA) and 93 % of Faraday efficiency. X-ray absorption fine-structure spectroscopy (XAFS) and density functional theory (DFT) calculations revealed that the bridging structure of NiO (aldehyde)-Co accelerated the electron transfer and the generation of reactive NiOOH. Besides, the p-d orbitals coupling among Co-S-Ni optimized the adsorption energies of HMF and *OH, facilitating the oxidation of 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) to FDCA and thereby enabling the deep HMFOR process. These results provide insights into the catalytic behavior and mechanism of the Co-Ni-based electrodes for electrocatalytic biomass upgrading.