A Co-MOF-derived Co₉S₈@NS-C electrocatalyst for efficient hydrogen evolution reaction

The exploitation of efficient hydrogen evolution reaction (HER) electrocatalysts has become increasingly urgent and imperative; however, it is also challenging for high-performance sustainable clean energy applications. Herein, novel Co₉S₈ nanoparticles embedded in a porous N,S-dual doped carbon composite (abbr. Co₉S₈@NS-C-900) were fabricated by the pyrolysis of a single crystal Co-MOF assisted with thiourea. Due to the synergistic benefit of combining Co₉S₈ nanoparticles with N,S-dual doped carbon, the composite showed efficient HER electrocatalytic activities and long-term durability in an alkaline solution. It shows a small overpotential of -86.4 mV at a current density of 10.0 mA cm^-2, a small Tafel slope of 81.1 mV dec^-1, and a large exchange current density (J ₀) of 0.40 mA cm^-2, which are comparable to those of Pt/C. More importantly, due to the protection of Co₉S₈ nanoparticles by the N,S-dual doped carbon shell, the Co₉S₈@NS-C-900 catalyst displays excellent long-term durability. There is almost no decay in HER activities after 1000 potential cycles or it retains 99.5% of the initial current after 48 h.