Modulating Trinary‐Heterostructure of MoS₂ via Controllably Carbon Doping for Enhanced Electrocatalytic Hydrogen Evolution Reaction

Abstract Understanding the phase transitions process of 2D transition metal dichalcogenides (2D‐TMDs) from semiconducting (2H) to metallic (1T, 1T′) phase provides directionality for the iteration of hydrogen evolution catalysis. So far, the phase engineering methods are intensively explored, serving as practical tools for discovering low‐cost novel nanomaterials for electronic and electrode devices in the realm of energy storage and catalysis. However, the heterostructures between 2H/1T, 2H/1T′, or 1T/1T′, functionalizing as critical active sites in the electrocatalytic process, are overlooked. Herein, a facile carbon doping paradigms, enabling augmentation of MoS 2 phase transition, together with density functional theory calculations and rationales to explain the counterintuitive directionality of transitions is reported. The experiment and simulation results indicate that the existence of carbon as interstitial atoms is more favorable to the phase transition than the substitution atoms. The heterogeneous interfaces between 2H and 1T or 1T′ are more conducive to charge transfer. As expected, the trinary‐heterostructure nanofilm displays excellent electrocatalytic activities both in micro‐electrochemical measurements and conventional electrolytic cells. The results provide a fresh insight into the 2D‐TMDs phase transition mechanism and guide for trinary‐heterostructure electrocatalysts for scalable production.