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 H2 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.