ZIF-Derived Cobalt Sulfides Embedded on Nitrogen-Doped Carbon Frameworks for Efficient Hydrogen Evolution Reaction

The development of efficient and durable catalysts for the hydrogen evolution reaction (HER) is essential for sustainable energy research. Cobalt sulfides (CoS_x) have attracted significant interest as prospective catalysts for the HER owing to their promising catalytic activity and high stability. In this study, CoS_x nanocrystals embedded in nitrogen-doped carbon frameworks (NC) are fabricated using a zeolite imidazole framework precursor via a two-step pyrolysis-sulfurization process, followed by combination with carbon black (CB) to create CoS_x-NC/CB as an efficient electrocatalyst for the HER. Interestingly, this catalyst displays a higher HER activity than that of the investigated materials, with an overpotential of 282 mV at a current density of 10 mA cm^− 2, along with a Tafel slope of 57.6 mV dec^− 1 in an acidic solution. This performance is attributed to the synergistic effect of CoS_x nanoparticles, nitrogen-doped carbon, and highly conductive CB, which improves the number of active sites, electron transfer, and electrochemical surface area. This outcome has significant potential for the development of economically viable catalysts for water splitting.