Defect-Rich Porous CoS_1.097/MoS₂ Hybrid Microspheres as Electrocatalysts for pH-Universal Hydrogen Evolution

As a clean and promising hydrogen production process, the electrochemical hydrogen evolution reaction (HER) is particularly important. However, its electrocatalytic activity is usually limited by the acid or base environment of the electrolyte. To achieve efficient conversion in energy storage, developing cost-effective nonprecious HER electrocatalysts at all pH values is highly required. Herein, defect-rich porous CoS1.097/MoS2 hybrid microspheres are synthesized via a one-step sulfurization method. As expected, the optimal pH-universal CoS1.097/MoS2 HER electrocatalyst shows overpotentials of 228, 249, and 341 mV at −10 mA cm–2 and small Tafel slopes of 59, 75, and 85 mV dec–1 in 0.5 M H2SO4, 1.0 M KOH, and 0.1 M PBS electrolyte, respectively. Furthermore, the CoS1.097/MoS2 also presents outstanding HER catalytic stability in a 21 h stability test. The outstanding performance of CoS1.097/MoS2 can be ascribed to the synergetic interplay of CoS1.097 and MoS2, with abundant defects and a hierarchically ordered interconnected micro/mesoporous structure.