Doping induced mixed polytypic interfaces of MoS2 for superior electrocatalytic hydrogen evolution

Metallic 1Tphase of MoS2 is desirable for accelerating electrochemical hydrogen generation from water due to its excellent electrical conductivity. However, it is challenging to synthesize stable 1T-MoS2 on a large scale using conventional chemical or physical routes. Here in, we report highly durable Mn-doping assisted in-plane 1T/2H mixed phases of MoS2 synthesized by a simple one-step hydrothermal method. The Mn-doping not only results in a favourable electronic modification in the host lattice but also in a structural evolution from 2H (trigonal prismatic) to 1T (octahedral) phase through sulfur-plane gliding with additional defects. The 1T/2H interfaces exhibit more active sites for hydrogen evolution reaction (HER) than its bulk 2H-counterpart. The developed electrode shows relatively low overpotential of 95 mV at a current density of 10 mA/cm2 and a low Tafel slope of 72 mV/dec in 0.5 M H2SO4. In addition, Density Functional Theory based calculations also support that Mn-doping in pristine 2H-MoS2 encourages a structural phase separation. Locally hybridized d-orbital’s of Mn induce the formation of 2H/1T interfaces. It results in the delocalization of electrons, and thus facilitates the hydrogen adsorption and desorption process, better than the 2H phase.