Journal ArticleCovalent surface modifications and superconductivity of two-dimensional metal carbide MXenesKamysbayev, Vladislav; Filatov, Alexander S.; Hu, Huicheng; Rui, Xue; Lagunas, Francisco; Wang, Di; Klie, Robert F.; Talapin, Dmitri V.Versatile chemical transformations of surface functional groups in 2D transition-metal carbides (MXenes) open up a new design space for this broad class of functional materials. We introduce a general strategy to install and remove surface groups by performing substitution and elimination reactions in molten inorganic salts. Successful synthesis of MXenes with O, NH, S, Cl, Se, Br, and Te surface terminations, as well as bare MXenes (no surface termination) was demonstrated. These MXenes show distinctive structural and electronic properties. For example, the surface groups control interatomic distances in the MXene lattice, and Ti n +1 C n ( n = 1, 2) MXenes terminated with Te 2− ligands show a giant, (>18%) in-plane lattice expansion compared to the bulk TiC lattice. Nb 2 C MXenes exhibited surface-group-dependent superconductivity.2020-08-2110195282Scienceeaba83110036-8075https://doi.org/10.1126/science.aba83111729420; 2004880National Science Foundation