Modulating the electronic structure of MoS2 nanosheets by Mn doping for improving hydrogen evolution reaction: an experimental and theoretical DFT-QTAIM study

This study provides experimental and theoretical analyses of the effects of Mn doping on the electronic structure of MoS2 nanosheets and its impact on the performance of the hydrogen evolution reaction (HER). Experiments show that Mn doping alters the electronic structure of MoS2. This leads to an enhanced HER activity. The Mn-MoS2 nanosheets with a Mn/Mo molar ratio of 1:15 exhibit an overpotential of approximately 238 mV at a current density of 10 mA/cm2 and a low Tafel slope of 68 mV/decade in 0.5 M H2SO4. Density Functional Theory calculations and Bader analysis indicate that the incorporation of Mn atoms into the basal plane of MoS2 nanosheets activates all in-plane S atom sites and three Mo atoms neighboring the Mn dopant, thereby reducing the adsorption free energy of H atoms. Further, the Mn dopant enhances the intrinsic electronic conductivity of MoS2 by reducing its bandgap, which leads to a rapid charge transfer across the basal plane during H2 evolution.