Regulating charge redistribution and active species in vanadium disulfide for boosting hydrazine-assisted alkaline...

Hydrazine-assisted water splitting provides a feasible approach for promoting energy-saving green hydrogen production. In this work, integrating disparate active sites within a single catalyst was proposed to optimize the distinct adsorption ability of key intermediates at their respective active sites during the hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER). This is achieved through dual modulated strategies of electronic structure and superficial active species in vanadium disulfide (VS₂) by doping Mo and anchoring cobalt hydroxide (Co(OH)₂). The resulting Co(OH)₂ anchored Mo-doped VS₂ (Co(OH)₂/Mo-VS₂) can serve as bifunctional electrocatalyst for both HzOR and HER. Experimental and theoretical results indicate that Co sites enhance water adsorption/activation and S sites promote water dissociation, synergistically facilitating the Volmer step on Co(OH)₂/Mo-VS₂. Simultaneously, the Co(OH)₂ in Co(OH)₂/Mo-VS₂ creates catalytic site for HzOR. Furthermore, the modulated electronic structure induced by Mo doping and the electron transfer at Co(OH)₂/Mo-VS₂ interface effectively promotes water dissociation and accelerates catalytic kinetics. Consequently, the Co(OH)₂/Mo-VS₂ exhibited an outstanding electrocatalytic activity with an overpotential of 41 mV for HER and an applied potential of 71 mV for hybrid water splitting at 10 mA cm^-2. These findings provide significant insights into designing the advanced electrocatalysts by rational regulation strategies and disclosing the underlying mechanism of enhanced catalytic activity.