Mechanical properties of transition metal carbo-chalcogenide with formula of X$$_2$$Y$$_2$$C (X: Nb, Ta, V; X = S, Se): a DFT study

Recently Majed et al. reported the synthesis of a new family of 2D transition metal carbo-chalcogenides including Nb(_2)S(_2)C and Ta(_2)S(_2)C using electrochemical lithiation followed by sonication in water (Adv Mater 34:2200574, 2022). Motivated by the recent experimental report, we investigate the mechanical properties of X(_2)Y(_2)X (X = Nb, Ta, V, Y = S, Se) monolayers by using density functional theory. We show the advantages and disadvantages of these monolayers in competition with transition metal dichalcogenides (TMDs) and MXenes from a mechanical point of view. We show that sulfur-based compounds are more energetically stable than Se-based compounds. In comparison with TMD monolayers and MXenes, the TMCCs are more stable than TMDs. Our results reveal that all monolayers are metals similar to their MXene counterparts. Results demonstrate that TMCCs are stiffer than TMDs and have higher (lower) Young moduli in comparison with the TMDs (MXenes) monolayer counterpart.