Hydrogen adsorption on Ti metalloporphyrin: From maximum loading to reversible storage
Gas Science and Engineering, cilt.153, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 153
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jgsce.2026.205961
- Dergi Adı: Gas Science and Engineering
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Anahtar Kelimeler: Adsorption energy, Density functional theory, Hydrogen storage, Kubas interaction, Titanium-doped porphyrin
- Ankara Üniversitesi Adresli: Evet
Özet
The adsorption behavior of molecular hydrogen on titanium metalloporphyrin (Ti–MP) was systematically investigated using density functional theory. Long-range corrected wB97XD functional calculations with a def2-TZVP basis set were employed to optimize geometries, evaluate vibrational and thermal corrections, and analyze electronic structures via natural bond orbital, Mulliken charge, and projected density of states methods. The study explores isolated Ti–MP complexes accommodating up to twenty H2 molecules, quantifying bond lengths, adsorption energies, and thermodynamic parameters. Results show that the first few H2 molecules, especially at low coverage ( n = 1–3), exhibit the strongest Kubas-type binding, evidenced by Ti–H2 distances around 1.9–2.0 Å, significant H–H bond elongation, and Ti 3 d –H2 σ/σ∗ hybridization. Adsorption becomes progressively weaker beyond the low-coverage regime, and high-loading states are increasingly outer-shell and physisorption-like. Although gravimetric density exceeds 10 wt% at full loading, the practically relevant reversible window is substantially smaller than the geometric maximum. Charge-distribution and frontier-orbital analyses confirm substantial electron transfer from Ti to the porphyrin scaffold and adsorbed hydrogen, while the porphyrin framework remains electronically and structurally intact upon hydrogenation. These findings provide a mechanistic and thermodynamic picture of hydrogen adsorption on Ti metalloporphyrin and clarify the difference between theoretical maximum uptake and practically reversible storage.