Stacking Sequence, Interlayer Bonding, Termination Group Stability and Li/Na/Mg Diffusion in MXenes

A versatile group of 2D carbide materials from the past decade, MXenes, have attracted attention for their rich chemistry and wide range properties. The perhaps best known MXene, namely, Ti3C2Tx, has been observed to stack in two distinct ways, simulations show that this influences interlayer bonding energy Li diffusion. In DFT study, six types Ti3C2T2 bonds resulting O, F, OH termination groups are assessed with respect stability. It is shown highly stable up 50% coverage, but unstable higher coverage. model predict stacking type based on shows degree hydrogen deciding factor. also tested V2CT2 Zr3C2T2, giving similar results those Ti3C2T2. By calculating migration barriers Ti3C2O2, we Li, Na, Mg orders magnitude faster diffusion favored by bonds. XRD patterns calculated both stackings they close indistinguishable, highlighting need caution when classifying stacking.