A combined DFT and AIMD investigation of titanium-based metal hydrides for hydrogen storage applications

Abstract

The hydrogen economy offers significant potential but faces challenges in large-scale implementation despite hydrogen’s abundance and environmental advantages. This study systematically investigates the hydrogen storage performance and structural, electronic, phononic, and mechanical properties of TiX 3 H 8 (X = Ni, Fe, V) hydrides using density functional theory (DFT) and ab initio molecular dynamics (AIMD). Electronic structure analyses indicate metallic behavior in all compounds. Mechanical stability satisfies the Born criteria, while bulk-to-shear modulus ratios and positive Cauchy pressures suggest ductile, minimally brittle characteristics. Phonon dispersion confirms dynamical stability, and AIMD simulations demonstrate thermal stability at 300 K. The calculated gravimetric hydrogen capacities are 3.83 wt% (TiV 3 H 8 ), 3.58 wt% (TiFe 3 H 8 ), and 3.45 wt% (TiNi 3 H 8 ), with desorption temperatures of 755 K, 585 K, and 536 K, respectively. Although slightly below U.S. Department of Energy targets, these findings identify TiX 3 H 8 hydrides as promising candidates for solid-state hydrogen storage applications. • Ab-initio study of TiX 3 H 8 (X = Fe, Ni, V) hydrides for hydrogen storage. • Stability validated through phonon dynamics, formation energies, and elasticity. • TiFe 3 H 8 , TiNi 3 H 8 , TiV 3 H 8 achieve volumetric H 2 storage of 189.3–171.9 g/L. • AIMD confirms kinetic stability of TiFe 3 H 8 , TiNi 3 H 8 , TiV 3 H 8 at 300 K. • TiX 3 H 8 hydrides show low H diffusion barriers, 0.63–1.62 eV activation energies.