The diffusion and desorption of tritium on Li2TiO3 (-133) surface from first-principles calculations

•The effective activation energy for tritium diffusion on the Li2TiO3 (-133) surface is 1.06 eV, which is higher than the activation energy reported for tritium diffusion on the (001) surface. Additionally, within the operational temperature range, its diffusion rate is lower than the reported data.•The activation energy for tritium molecule desorption from the (-133) surface is 1.46 eV, which is lower than the value reported for the (001) surface.•The further tritium migrates in a `non-bonded` state, the higher the activation energy required for the process. Li2TiO3 is one of the most promising solid breeder materials for nuclear fusion reactor. Diffusion on the surface is a vital step of the tritium release process. In this work, the diffusion behavior of tritium atoms on the (-133) surface and the desorption of T2 molecules from the (-133) surface are systematically investigated. Possible adsorption sites, local diffusion pathways, and their corresponding activation energies have been identified using first-principles calculations and the climbing image nudged elastic band (CI-NEB) method. The diffusivity and effective activation energy for tritium diffusion on the (-133) surface have been determined using kinetic Monte Carlo (KMC) simulations. The activation energy for T2 desorption from the (-133) surface has also been investigated. The effective activation energy for tritium diffusion on the (-133) surface is found to be 1.06 eV, whereas the activation energy for T2 molecule desorption is 1.46 eV. The (-133) surface exhibits a higher activation energy for tritium diffusion but a lower activation energy for T2 desorption compared to the (001) surface.