A general strategy to stabilize 1T-MoS using MXene heterostructures and unlock its hydrogen evolution reaction capabilities.

The two-dimensional (2D) metallic phase of MoS, 1T-MoS, has extraordinary electrical conductivity in contrast to the common 2D semiconducting phase, 2H-MoS. However, the thermodynamic instabilities of 1T-MoS hinder its application. In this work, we investigate the possibilities of stabilizing 1T-MoS through heterostructure design using first-principles calculations. We found that MXene-based heterostructures could hamper phase transitions from 1T-MoS to 2H-MoS enabled by a larger phase transition kinetic energy barrier. Based on this finding, we propose a general and effective strategy for stabilizing 1T-MoS, that is, building heterostructures using 1T-MoS and oxygen-functionalized MXenes. Besides, we have also observed that due to the occurrence of electron transfer in the heterostructure, 1T-MoS in the heterostructure exhibits improved hydrogen adsorption free energy and more active sites compared to the monolayer 1T-MoS. These findings provide guidance for promoting and developing 1T-MoS for practical applications. In addition, the proposed heterostructure design strategy could inspire the study of phase transition behaviors and electrochemical properties of materials using interfaces.