Modeling and simulation of the structural, and optoelectronic properties of aluminum trihydride (β-AlH3) for hydrogen storage

Hydrogen is a promising clean energy source, but its storage poses challenges. In this research, we conducted an in-depth study of the structural and optoelectronic properties of the β-${\text{AlH}}_3$ phase as a potential material for hydrogen storage. Using the density functional theory (DFT)-based Wien2k code, we optimized the structure of β-${\text{AlH}}_3$. Hydrogen storage properties show that β-${\text{AlH}}_3$ contains 10.1% hydrogen by weight, which is a significant amount. Electronic properties reveal that this material is a semiconductor with a wide indirect bandgap of 5.947 eV, obtained by the generalized gradient approximation with modified Becke-Johnson correction (GGA-mBJ). The optical response of β-${\text{AlH}}_3$ to photons with energies from 0 to 10 eV is also examined for a better understanding of this material. β-${\text{AlH}}_3$ exhibits a static dielectric permittivity value ${\epsilon }_1\left(\omega \right)$ of 2.1, indicative of its semiconducting nature. The optical conductivity ${\sigma }_1\left(\omega \right)$ shows peaks at 7.25 eV and 8.5 eV, while the absorption coefficient α(ω) increases significantly above the band gap of 5.947 eV, with peaks at 7.2 eV and 9 eV. The refractive index n(ω) and extinction coefficient κ(ω) both display notable features at 7.2 eV and 9 eV, reflecting substantial electronic transitions and optical resonances.

This research is crucial to understanding how this material can meet the technological demands of hydrogen storage. The results provide valuable insights into the potential of β-AlH₃ within the future energy landscape, highlighting both advances and challenges in this promising field.