Nanostructured Cobalt and Copper Sulfides for Applications as Electrocatalysts for High-Efficiency Alkaline Hydrogen Evolution

Abstract

The development of cost-effective and durable non-precious-metal catalysts for the hydrogen evolution reaction (HER) is critical for advancing sustainable hydrogen production via water electrolysis. Herein, we report a facile strategy for synthesizing a three-dimensional self-supported Co₉S₈/Cu₂S heterostructured electrocatalyst through in situ growth of Cu(OH)₂ nanorod arrays on copper foam, followed by hydrothermal sulfidation and cobalt incorporation. Structural characterization reveals that the twisted morphology of Co₉S₈/Cu₂S forms a highly porous network with abundant exposed active sites, while the conductive Cu substrate ensures efficient charge transfer. Electrochemical evaluations in 1 M KOH demonstrate exceptional HER performance for the optimized Co₉S₈/Cu₂S catalyst, achieving an ultralow overpotential of 134 mV at 10 mA cm^–2 and a Tafel slope of 70 mV dec^–1, surpassing most reported non-noble-metal sulfides. Remarkably, the catalyst exhibits outstanding durability, retaining 95% of its initial activity after 1400 cyclic voltammetry cycles and sustaining stable current densities for 48 h under a constant potential. This work provides fundamental insights into heteroatom doping and heterointerface engineering for designing high-performance transition metal sulfide catalysts.