Designing Hydrogen Permeation Barriers in Titanium Aluminium Nitride through First Principles Density Functional Theory Calculations

We investigated hydrogen permeation in titanium aluminium nitride (TiAlN) using ab initio density functional theory (DFT) for cubic and hexagonal crystal structures. Despite the significance of hydrogen barriers, the potential of TiAlN has not been fully explored. We analyzed site specificity, temperature-dependent insertion, and atomic hydrogen migration path energies. Our research highlights the decisive role of crystallographic structure over chemical composition in designing materials resistant to hydrogen absorption. However, once absorbed, hydrogen diffusion is governed by the local chemical environment. Specifically, hydrogen migration through an Al-N plane requires more energy than through Ti-N, which affects the overall diffusion process. We found hydrogen absorption is highly endothermic, with insertion energies from 50 to 320 kJ/mol of hydrogen atoms, indicating low uptake probability at ambient conditions. Higher temperatures further increase the energy required, making absorption less favourable. We also identified substantial energy barriers in the hexagonal structure, with peaks up to 276 kJ/mol, indicating a very low probability of migration for hydrogen. These findings underscore TiAlN's exceptional resistance to hydrogen permeation, making it suitable for hydrogen storage applications.