Carbon layer-protected self-supporting CoSe₂ nanowire arrays for durable hydrogen evolution reaction catalysts

Cobalt diselenide (CoSe2) is considered a promising catalyst for hydrogen evolution reaction (HER); however, the limited active number, agglomeration, and quick deactivation by acid etching hinder its broad adoption. Herein, we report carbon layer-covered CoSe2 nanowire arrays grown on carbon cloth (C@CoSe2/CC). The structure of the nanowire array demonstrates synergistic effects in promoting the infiltration of electrolytes, accelerating the diffusion of H-2 bubbles, and preventing CoSe2 from being etched by the electrolyte. Consequently, the overpotential and Tafel slope (193 mV, 54.3 mV dec(-1)) obtained sustained 24 h with a negligible overpotential deterioration. This study provides insights into optimizing the intrinsic activity of active sites.