Theoretical evidence of self-intercalated 2D materials for battery and electrocatalytic applications

Covalently bonded two-dimensional (2D) self-intercalated transition metal chalcogenides (i.e., ic-2Ds) have been recently fabricated experimentally, and their properties are highly tunable by stoichiometry and composition. Inspired by this progress, we focus on the applications of ic-2Ds in the field of electrochemistry and systematically investigate their performance in lithium-ion batteries (LIBs) and electrocatalytic hydrogen evolution reactions (HER). By means of density functional theory calculations, seven 3d-metal ic-2Ds are confirmed to be thermodynamically, mechanically, and thermally stable. The metallicity and abundant active sites endow these ic-2Ds with the potential as excellent electrode materials and HER catalysts. Among them, Ti7S12 and V7S12 exhibit the potential as anode materials for LIBs, showing low Li diffusion energy barriers, suitable open-circuit voltages, and ultrahigh capacity of 745.6 and 723.9 mA hg-1, respectively; Cr7S12 and Co7S12 show promises for HER with moderate hydrogen adsorption strengths. This theoretical study provides a new avenue for the application of newly reported ic-2Ds in various electrochemical energy conversion and storage applications.