Effective CoxSy HER Electrocatalysts Fabricated by In‐Situ Sulfuration of a Metal‐Organic Framework

Abstract A sulfur and nitrogen containing cobalt metal‐organic framework (Co−MOF) was chosen as a precursor to prepare cobalt sulfides as HER electrocatalysts. Cobalt sulfides with different stoichiometries, CoS 1.097 , Co 9 S 8 , Co 9 S 8 /CoS 1.097 , and Co 9 S 8 /CoS 1.097 /rGO, were obtained through a phase control method and in‐situ sulfuration of the MOF precursor. Co 9 S 8 /CoS 1.097 /rGO shows excellent HER performance, with an overpotential of 50 mV at a current density (j) of 1 mA cm −2 (η 0 ), and 188 mV at a current density of 10 mA cm −2 (η 10 ), stemming from the synergistic effect of Co 9 S 8 , CoS 1.097 , high specific surface area and the nitrogen and sulfur doped carbon matrix.