Ni―V Dual Sites Boost Nucleophilic Electrooxidation Coupling With Cathodic Hydrogen Production

Abstract

The integration of electrocatalytic 5-hydroxymethylfurfural (HMF) oxidation with the hydrogen evolution reaction (HER) is a win-win strategy that enables the concurrent production of high-value chemicals and low-energy hydrogen. However, HMF oxidation suffers from competing adsorption between organics and OH- along with continuous redox cycling of active sites, leading to unsatisfactory activity, selectivity, and stability. To address these challenges, we designed a VO2/Ni3S2 composite catalyst with rich cationic vacancies and low vanadium content. This catalyst creates Ni & horbar;V dual active sites that trigger an alternative reaction pathway. VO2/Ni3S2 achieves high HMF conversion (97.1%), Faradaic efficiency (96.0%), and selectivity (98.93%) toward FDCA, along with robust stability. In an integrated HMFOR||HER system using VO2/Ni3S2 for both electrodes, a current density of 100 mA cm-2 was attained at a low cell voltage of 1.76 V. Mechanistic studies reveal that VO2-induced vacancies promote the formation of high-valence Ni species, while adjacent V sites enhance OH adsorption. This configuration enables balanced co-adsorption of HMF and OH-. Unlike conventional single-site Ni catalysis, the Ni & horbar;V dual sites optimize the dehydrogenation pathway while preserving the high oxidation state of Ni. This study sheds new light on the catalyst design for energy-efficient biomass valorization and hydrogen production.