Layered Post-Transition-Metal Dichalcogenides (X-M-M-X) and Their Properties

A^III B^VI chalcogenides are an interesting group of layered semiconductors with several attractive properties, such as tunable band gaps and the formation of solid solutions. Unlike the typically sandwiched structure of transition-metal dichalcogenides, A^III B^VI layered chalcogenides with hexagonal symmetry are stacked through the X-M-M-X motif, in which M is gallium and indium, and X is sulfur, selenium, and tellurium. In view of the inadequate study of the electrochemical properties and great interest in layered materials towards energy-related research, herein the inherent electrochemistry of GaS, GaSe, GaTe, and InSe has been studied, as well as the exploration of their potential as hydrogen evolution reaction (HER) electrocatalysts. All four materials show redox peaks during cyclic voltammetry measurements. Furthermore, insights into catalysis of the HER are provided; these indicate the conductivity and number of active sites of the materials. All of these findings have important implications on their possible applications.