First-principles investigation of transition metal doping effects on H 2 dissociative adsorption in TiFe-based alloys

Abstract

TiFe alloys are important hydrogen storage materials. This study uses densityfunctional theory (DFT) to systematically investigate how 3d and 4d transition metal (TM) (except Tc) on the dissociative adsorption behavior of H 2 on TiFe (110) surface was systematically investigated by using density-functional theory (DFT) calculations.Calculations indicate that the optimal adsorption sites for H₂ on the pristine surface are adjacent Fe-Fe bridging sites. Calculations of adsorption energies for pristine and doped surfaces reveal: most transition metal dopants (particularly 4d elements) fail to significantly reduce the adsorption energy of H₂ on the TiFe (110) surface. Whereas Co (substituting Fe, Ti sites) and Sc (substituting Ti sites) significantly reduce adsorption energies. Considering both substitution propensity and adsorption performance, the Co substituted Fe and Sc substituted Ti systems demonstrate the greatest application potential. Electronic structure analysis shows that doping with different elements causes different degrees of orbital hybridization and charge redistribution. This is the main reason for the changes in the adsorption capacity of doped surfaces.