Cr<sup>3+</sup> Ion‐Induced Phase Stabilization of 1T−MoSe<sub>2</sub> with Abundant Active Sites for Efficient Hydrogen Evolution Reaction
Ayan Mondal, Harish Reddy Inta, Varun Bheemireddy, Sourav Ghosh, Venkataramanan Mahalingam
Abstract
Abstract The electrocatalytic performance of transition metal dichalcogenides (TMDs) can be hugely impacted by their phase and electronic structure. In this regard, stabilization of the 1T (metallic) phase is a substantial challenge to attain superior electrocatalytic activity compared to its thermodynamically stable polymorph (2H phase). This report provides a simple approach to introduce the 1T phase into 2H−MoSe 2 through heteroatom (Cr 3+ ) doping using a hydrothermal method. 1T/2H−MoSe 2 (x Cr) (x=1,2,3 and 5) materials have shown better electrocatalytic HER activities compared to the 2H−MoSe 2 , especially 2% Cr 3+ doped MoSe 2 (1T/2H−MoSe 2 (2 Cr)) have shown the best catalytic activity. 1T/2H−MoSe 2 (2 Cr) exhibits a current density of 20 mA cm −2 at an overpotential of 176 mV, low Tafel slope of 77 mV/dec, high double layer capacitance (C dl ) of 78.3 mF cm −2 and good cyclic stability. The improved electrocatalytic activity of 1T/2H−MoSe 2 (2 Cr) could be attributed to the high conductance, high 1T phase content and the greater number of active sites resulting from the introduction of Cr 3+ ions into MoSe 2 . In addition, density functional theory (DFT) studies predict that the introduction of Cr 3+ ions into the MoSe 2 monolayer increases the conduction electron density in the basal plane at room temperature which in turn supports the generation of additional active sites along the basal plane.