Adsorption of noble fission gas atoms Xe and Kr on Ti- and V-based bare MXenes: An ab-initio DFT investigation

Abstract

We have studied the adsorption of noble fission gas atoms Xe and Kr on early 3d metal carbide and nitride MXenes, i.e., M2X (M=Ti, V; X= C, N) by performing van der Waals corrected density functional based simulations. These results show that the adsorption of Xe and Kr is stable on all the MXene surfaces considered in this work. For Ti2C, the binding energies and adsorption distances of Xe and Kr are comparable to other 2D materials such as graphene. The replacement of C with N in Ti-based MXene (Ti2N) results in a marginal improvement in the binding strength. In contrast, a noticeable increase in the binding energy is observed for V2X, accompanied by reduction in adsorption distance. It is further demonstrated that the marked increase in Xe/Kr binding energy on V2X as compared to Ti2X is a consequence of much stronger interfacial interaction for the former, highlighted by much larger charge density overlap within the interface region. Moreover, V2X surface increases the selective adsorption of Xe over Kr as indicated by enhanced binding energy difference between Xe and Kr. Further, the adsorption of Xe on oxygen terminated V2C (V2CO2) is also studied which showed that the binding strength reduces by ∼ 0.06 eV due to full oxygen termination. Overall, these results underscore V2X as an efficient Adsorptive material of noble fission gas atoms in comparison to previously studied 2D materials.