Exploring the hydrogen interaction on Zn12O12 nanocages: A first-principles study

This study uses density functional theory (DFT) a powerful computational method, to analyze how the hydrogen molecules adsorb in the Zn 12 O 12 nanocage, a promising material for lightweight hydrogen storage applications. The adsorption mechanism is primarily governed by the charge redistribution and polarization effect originating from Zn O bonds, which induce preferential binding of H 2 molecules at Zn sites. Detailed electronic structure analysis, supported by Quantum Theory of Atoms in Molecules (QTAIM) and Non-covalent Interaction (NCI) calculations, reveals that these interactions are weakly physisorption yet highly stable, ensuring reversible adsorption. The compute average adsorption energy is approximately −0.04 eV per H 2 molecule, indicating facile adsorption-desorption under ambient conditions. Zn 12 O 12 nanocages demonstrate an impressive gravimetric hydrogen storage capacity exceeding 7.6 wt%, surpassing several current nanostructured materials. Furthermore, ab initio molecular dynamics (AIMD) simulations conducted at 300 K confirm the structural stability of Zn 12 O 12 during H 2 adsorption. To further enhance the tunability of Zn 12 O 12 nanocage properties for hydrogen storage applications, alkali metal doping (Li, Na, K) was investigated by substituting a Zn atom with an alkali element. Structural optimization and stability assessments confirm that the doped nanocages preserve their geometric integrity, while molecular electrostatic potential (MEP) analysis reveals pronounced localized charge redistribution around the dopant site. Although the computed average H 2 adsorption energies remain comparable to the pristine nanocage, the induction of alkali dopants generates chemically active regions that could facilitate tailored surface reactivity, enhance spillover processes, and enable applications specific functionalization. These findings provide deep insights into the H 2 retention mechanisms within Zn 12 O 12 clusters, highlighting their versatility and potential for next-generation hydrogen energy systems. • DFT simulations reveal hydrogen interaction analysis in Zn 12 O 12 nanocage. • Adsorption is driven by charge transfer and polarization from ionic Zn O bonds. • Electron transfer from Zn to O boosts polarization, aiding H 2 adsorption at Zn sites. • QTAIM and NCI analyses confirm stable, non-covalent H 2 adsorption on nanocages. • Zn 12 O 12 nanocages show >7.00 wt% H₂ uptake, surpassing standard interaction levels.