Ultrafast synthesis of V8C7 catalysts for efficient chemical hydrogen evolution via decoupled water electrolysis in a dual-circuit redox flow battery

Producing hydrogen via decoupled water electrolysis in a dual-circuit redox flow battery (RFB) offers several advantages over the traditional water electrolysis technologies in terms of safety, flexibility and adaptability with renewable energy. Identifying cost-effective and stable catalysts for chemical hydrogen evolution reaction (HER) is important for achieving high efficiency. Herein, we present the ultrafast synthesis of vanadium carbide catalysts anchored on carbon cloth (V₈C₇/CC) with a facile high-temperature shock approach towards highly efficient chemical HER via decoupled water electrolysis in a dual-circuit RFB. Density functional theory calculations demonstrate the moderate hydrogen adsorption free energy of −0.227 eV on the surface of V₈C₇/CC enhanced hydrogen adsorption kinetics. Consequently, the V₈C₇/CC catalyst shows a rapid hydrogen production rate of 5.94 mmol h⁻¹ mg⁻¹ and a high turnover number of 3.8, which are comparable with the benchmark platinum and superior to molybdenum carbide catalysts. Moreover, the V₈C₇/CC exhibits remarkable activity and stability for chemical HER in a V–Ce RFB with a home-made reactor for decoupled water splitting.