Ultrathin molybdenum disulfide/carbon nitride nanosheets with abundant active sites for enhanced hydrogen evolution

The exploration of highly active catalysts for hydrogen evolution reaction (HER) is beneficial to realize high catalytic activity and enhance kinetics for water splitting. Herein, flower-like molybdenum disulfide/carbon nitride (MoS₂/C₃N₄) nanosheets with thickness of 4.6 nm and enlarged interlayer spacing of 0.64 nm were synthesized via a facile hydrothermal method. As expected, the ultrathin thickness endowed MoS₂/C₃N₄ with abundant active sites, ensuring outstanding catalytic activity and excellent stability for HER in alkaline electrolyte. MoS₂/C₃N₄ nanocomposites can offer an onset overpotential of 153 mV versus reversible hydrogen electrode (RHE). Notably, the Tafel slope value is only 43 mV dec^-1, which is significantly better than those of reported MoS₂-based hydrogen evolution catalysts, revealing superior HER performance of MoS₂/C₃N₄, particularly in catalytic kinetics. More significantly, density functional theory (DFT) calculations further verify that rich active sites confined in ultrathin nanostructure of g-C₃N₄ nanolayers could increase the activity of MoS₂/C₃N₄ and result in enhanced HER efficiency. This study indicates that rational interaction between two different 2D materials can significantly facilitate H₂ generation, which endows extraordinary HER activity.