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

Abstract

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 M2X stoichiometry reveal an easy initial N2 fixation and dissociation, where N2 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 M2XN2 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 N2 adsorption and dissociation at nearly full N-covered adlayers, which is yet achievable for almost half of the explored M2X seeds. The present results unfold the possibility of expanding, controlling, and tuning the composition, width, and structure of the MXene family.

Mo3C2: Active Electrocatalysts for Spontaneous Nitrogen Reduction Reaction

“…It is known that there are two possible configurations for N 2 adsorption (end-on and side-on configurations), in which the end-on configuration denotes the N 2 adsorption on the top site and the adsorption on bridge or hollow sites is side-on configuration. N 2 is known to strongly adsorb on pristine MXenes. , As shown in Figure , the adsorption energies (Δ E *N2 ) of N 2 on the top, bridge, and hollow sites are −1.21, −0.92, and −1.13 eV, respectively. Therefore,N 2 adsorptions on the top and hollow sites are preferred.…”

“…N 2 is known to strongly adsorb on pristine MXenes. 38,39 As shown in Figure 2, the adsorption energies (ΔE *N2 ) of N 2 on the top, bridge, and hollow sites are −1.21, −0.92, and −1.13 eV, respectively. Therefore,N 2 adsorptions on the top and hollow sites are preferred.…”

Surface termination dependent carbon dioxide reduction reaction on Ti3C2 MXene

“…56 The generalized gradient approximation (GGA) Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional 57 was used, accurately suited in the description of MXenes energetics. 58–60 Additionally, Grimme's D3 approach was included to account for dispersive force interactions. 61 The core electron density and its impact on the valence electron density were described using the projector augmented wave (PAW) method developed by Blöchl, 62 as implemented by Kresse and Joubert.…”

Multiscale Computational Approaches toward the Understanding of Materials

“…Recently, we studied the possibility of epitaxially synthesizing MXenes, by taking advantage of the easy nitrogen dissociation that occurs on the surface of these materials. [ 230 ] The calculations show that the formation of fully N‐covered M 2 XN 2 is kinetically possible for some M 2 X surfaces. Also, additional early transition metal adlayers are thermodynamically attainable, which can lead to M′ 2 M 2 XN 2 MXenes.…”