Unsaturated Sulfur Edge Engineering of Strongly Coupled MoS2 Nanosheet-Carbon Macroporous Hybrid Catalyst for Enhanced Hydrogen Generation

The low hydrogen adsorption free energy and strong acid/alkaline resistance of layered MoS2 render it an excellent pH-universal electrocatalyst for hydrogen evolution reaction (HER). However, the catalytic activity is dominantly suppressed by its limited active-edge-site density. Herein, a new strategy is reported for making a class of strongly coupled MoS2 nanosheet-carbon macroporous hybrid catalysts with engineered unsaturated sulfur edges for boosting HER catalysis by controlling the precursor decomposition and subsequent sodiation/desodiation. Both surface chemical state analysis and first-principles calculations verify that the resultant catalysts exhibit a desirable valence-electron state with high exposure of unsaturated sulfur edges and an optimized hydrogen adsorption free energy, significantly improving the intrinsic HER catalytic activity. Such an electrocatalyst exhibits superior and stable catalytic activity toward HER with small overpotentials of 136 mV in 0.5 M H2SO4 and 155 mV in 1 M KOH at 10 mA cm(-2), which is the best report for MoS2-C hybrid electrocatalysts to date. This work paves a new avenue to improve the intrinsic catalytic activity of 2D materials for hydrogen generation.