Co₃S₄/Co₉S₈ doped nitrogen-enriched carbon polyhedron structures as an efficient catalyst for hydrogen evolution reaction

The development of stable non-noble and cost-effective metal sulfide-based electrocatalyst materials for hydrogen evolution reaction (HER) is still a great challenge. Herein, we report the rationally designed electrocatalysts containing Co₃S₄/Co₉S₈ co-doped nitrogen-enriched porous carbon polyhedrons (Co₃S₄/Co₉S₈/NC PHs). The Co₃S₄/Co₉S₈/NC PHs were achieved from Zeolitic imidazolate framework-67 PHs by adding sulfur powder and then placing them in an inert atmosphere at 375 °C for 2 h. The prepared electrocatalyst materials were analyzed using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, and X-ray photoelectron spectroscopy techniques. The HER catalytic activity of the Co₃S₄/Co₉S₈/NC PHs exhibited the superior overpotential performance of 134 mV at a current density of 10 mA cm⁻² with the Tafel slope of −119 mV dec⁻¹. Additionally, the results from chronopotentiometry maintained a strong kinetic response as well as the long cycling stability of 100 h for the Co₃S₄/Co₉S₈/NC PHs electrocatalyst at a constant current density of −10 mA cm⁻² with 8.4% decay rate. This study demonstrates a new strategy for hydrogen generation synthesizing non-noble catalyst materials with excellent HER activities.