MXenes à la Carte : Tailoring the Epitaxial Growth Alternating Nitrogen and Transition Metal Layers.

A high-throughput analysis based on density functional simulations underscores the viable epitaxial growth of MXenes by alternating nitrogen and metal adlayers. This is supported by an exhaustive analysis of a number of thermodynamic and kinetic thresholds belonging to different critical key steps in the course of the epitaxial growth. The results on 18 pristine N- and C-based MXenes with M 2 X stoichiometry reveal an easy initial N 2 fixation and dissociation, where N 2 adsorption is controlled by the MXene surface charge and metal d-band center and its dissociation controlled by the reaction energy change. Furthermore, formation energies indicate the plausible formation of N-terminated M 2 XN 2 MXenes. Moreover, the further covering with metal adlayers is found to be thermodynamically driven and stable, especially when using early transition metal atoms. The most restrictive analyzed criterion is the N 2 adsorption and dissociation at nearly full N-covered adlayers, which is yet achievable for almost half of the explored M 2 X seeds. The present results unfold the possibility of expanding, controlling, and tuning the composition, width, and structure of the MXene family.