This study explores the solid-state hydrogen storage capacity of A
2
SnH
6
(A = Li, Na, K) double perovskite hydrides. The substitution of Li with Na and K leads to an increase in lattice parameters from 7.56 to 7.73 and 7.99 Å. The enthalpy of formation and AIMD computation confirm their thermodynamic and thermal stabilities. The gravimetric hydrogen storage capacities decrease from 4.36 wt% (Li
2
SnH
6
) to 3.54 wt% (Na
2
SnH
6
) to 2.97 wt% (K
2
SnH
6
). All these configurations have wide indirect band gaps (2.74–3.12 eV), demonstrating their semiconducting nature, making them viable for UV photocatalytic water splitting. The calculated values of Pugh B
0
/G are Li
2
SnH
6
= 4.31, Na
2
SnH
6
= 2.59, and K
2
SnH
6
= 1.94, confirming their ductile nature. Furthermore, Na
2
SnH
6
exhibits the highest thermoelectric figure of merit (ZT = 0.79). While Li
2
SnH
6
provides the highest gravimetric hydrogen capacity, Na
2
SnH
6
exhibits the lowest predicted desorption temperature (311.07 K), compared with 337.36 K for K
2
SnH
6
. Overall, Na
2
SnH
6
emerges as the most promising candidate for meeting the U.S. DOE hydrogen storage targets.
Usman Saeed, Ghulam M. Mustafa, N. A. Noor et al.· Scientific Reports· 0 citations
A systematic density functional theory study of hydrogen bonding, cooperative binding, and Grotthuss proton transfer in PVA/CA/H₃PO₄ proton exchange membranes is presented. Twenty-three calculations were performed at the B3LYP-D3BJ/6-31G* level using ORCA 6.1.1, encompassing geometry optimisation, potential energy surface scanning, transition state verification, nudged elastic band analysis, natural bond orbital analysis, electron localisation function mapping, and a 65-atom crosslinked wet membrane model. The esterification energy is − 12.4 kJ/mol; single H₃PO₄ binding is − 78.1 kJ/mol; and cooperative binding of two H₃PO₄ molecules reaches − 203.0 kJ/mol. The gas-phase proton transfer barrier of 37.8 kJ/mol is reduced to 19.5 kJ/mol in the fully crosslinked wet environment, with the product state 9.3 kJ/mol more stable than the reactant. NBO bond-order analysis and ELF mapping support a local hydrogen-bond-mediated proton-transfer event, representing an elementary proton-hopping step rather than direct proof of a complete long-range Grotthuss conduction mechanism. A 20-step desorption PES (+ 75.9 kJ/mol) combined with hydration analysis (ΔG = − 278.0 kJ/mol) provides a quantum-mechanical interpretation of partial acid retention. DFT-predicted IR frequencies reproduce all major peaks within 0–110 cm⁻¹.
