Hydrogen interaction with Mn-doped Zr2Fe (101) surface: A DFT study

Abstract

The metal getter materials play a pivotal role in the treatment of tritium-containing waste gas, which is one of the most important tasks in fusion reactions, owing to the characteristics of no tritiated water product and easy recovery by the form of reversible metal hydrides. As the most promising and attractive hydrogen isotopes trapping materials for metal getters, Zr2Fe alloy has the advantages of low thermal neutron absorption, high corrosion resistance, fast hydrogen absorption rate, and high absorption efficiency, which have attracted great attention. Though pristine/Mn-doped Zr2Fe have been widely used to trap tritium from nitrogen and inert gases, an atomic-scale description of the inherent interaction mechanism between hydrogen and pristine/Mn-doped Zr2Fe surface is still lacking. Herein, density functional theory (DFT) calculations were employed to study the effect of doping Mn on the adsorption, dissociation and diffusion of hydrogen on the Zr2Fe(101) surface. It is found that the number of adsorption sites and adsorption strength of hydrogen increase when a Fe atom is substituted by a Mn atom. In addition, the dissociation and diffusion barriers of hydrogen are lowered on the Mn-doped surface. The electronic structure analysis shows that the adsorptions of hydrogen molecules cause more electron transfer to the surfaces and there exists strong interaction between hydrogen and doping Mn. Consequently, this should enhance the hydrogen storage performance of Zr2Fe alloy, due to the surface adsorption and diffusion of hydrogen being improved by doping Mn. All these findings can provide insightful guidance for future research to improve the hydrogen storage capacity of Zr-based alloy materials and the design of metal getters for tritium-containing waste gas treatment.