Hydrogen Diffusion in Ti3C2 MXenes

For energy storage in 2D MXenes using hydrogen, it is crucial to understand the relevant diffusion mechanisms. Density functional theory was used to determine hydrogen migration barriers, hopping frequencies, enthalpy and entropy of vacancy formation, and the diffusion coefficient of various possible migration paths. The results show that H diffusion is primarily governed by interstitial diffusion. For all investigated diffusion paths, the diffusion coefficients and prefactors, D0, the corresponding activation energy, E, and the hopping frequencies are calculated from the ab initio approach.