Optimizing MoS2 Edges by Alloying Isovalent W for Robust Hydrogen Evolution Activity

Previous studies revealed that HER activities on MoS2 could be boosted through exotic doping to introduce active centers. However, it is difficult to dope exotic elements into MoS2 with a high concentration due to their different chemical properties from host elements. Here, we theoretically and experimentally optimize the MoS2 edges through substituting Mo with different concentrations of isovalent W. The simulations predict that 50% substitution of Mo by W shows the best catalytic activity because of the reduction of H adsorption free energy and facilitation of charge transfer. Experiments demonstrate that the Mo0.5W0.5S2 significantly enhances HER performance of MoS2-based compounds, having an onset potential of −37 mV and achieving 10 mA cm–2 with an overpotential of 138 mV.