2D Mn Doped MoS$_2$: An Efficient Electrocatalyst for Hydrogen Evolution Reaction

Abstract

Earth-abundant two-dimensional (2D) pristine transition metal dichalcogenides (TMDs) have emerged as a superlative class of materials for several applications in electronic devices, energy storage devices, gas sensing, etc., and they have recently attracted great attention, owing to their good catalytic activity and excellent stability toward electrochemical H2 Evolution Reaction (HER). Each individual layer of the TMDs consists of three atomic layers in which the transition metal is sandwiched by two chalcogens. To activate the inert basal plane of the pristine 2D TMDs, it is needed to create some defects or doping of some heteroatoms in the pristine TMDs. Phase engineering techniques have been used to activate the basal plane of the 2D TMDs. In this article, we have computationally developed 2D monolayer Mn-MoS$_2$ material and its application in HER. Stable S terminated edge of the MoS$_2$ shows low catalytic activity due to its inert basal plane, so to exploit these edges for improved performance we doped Mn in the pristine MoS$_2$ material. Using trailblazing and state of the art first principles-based density functional theory we performed methodical and rigorous inspection of electronic structures and properties of monolayer Mn doped MoS$_2$ to be a promising alternative to noble metal-based catalysts for HER. Periodic 2D slab of Mn-MoS$_2$ was created to study the electronic properties and the reaction pathway occurring on the surface of the material has been delved into by creating Mn$_1$Mo$_9$S$_{21}$ molecular cluster model. Our study reveals that the 2D Mn-MoS$_2$ monolayer based catalyst follows the Volmer-Heyrovsky reaction with very low energy barriers during the HER mechanism. This study is focused on designing a low cost and efficient electrocatalyst for HER by using earth abundant TMDs and lowering the activation barriers by scrutinizing the kinetics of the reaction for reactivity.