First principles study of two-dimensional early transition metal carbides

Recently, we reported on the facile synthesis of a number of two-dimensional early transition metal carbides and nitrides, derived from the MAX phases, that we labeled MXenes . Herein, we report on the electronic and elastic properties—investigated by first principles calculations utilizing the generalized gradient approximation within the density functional theory—of the following two-dimensional transition metal carbides: Ti_2C, Ti_3C_2, Ti_4C_3, V_2C, Cr_2C, Zr_2C, Hf_2C, and Ta_2C, Ta_3C_2, and Ta_4C_3. Similar to the MAX phases, the MXenes are found to be metallic and possess high elastic moduli when stretched along the basal planes.