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<p>The interaction of molecular hydrogen with pristine and Sc-decorated pillar[5]arene (P5) was investigated using density functional theory to elucidate the mechanisms governing hydrogen adsorption. The pristine macrocycle exhibits very weak physisorption, with negligible interaction strength and no activation of the H–H bond. In contrast, scandium decoration introduces well-defined adsorption sites and significantly enhances hydrogen binding. The fully decorated 5Sc–P5 system shows adsorption energies in the range of − 0.163 to − 0.380&#xa0;eV per H₂ molecule, accompanied by moderate H–H bond elongation. Electronic structure analysis (PDOS and IGMH) reveals clear hybridization between H 1s and Sc 3d orbitals, consistent with a Kubas-type interaction mechanism involving σ-donation and back-donation. Thermodynamic analysis based on a grand canonical approach predicts a maximum hydrogen uptake of 25&#xa0;H₂ molecules (6.2 wt%), with a practical reversible capacity of 5.2 wt% under near-ambient conditions (30&#xa0;bar, 298&#xa0;K / 3&#xa0;bar, 373&#xa0;K). These results demonstrate that scandium functionalization effectively transforms pillar[5]arene into a promising host for reversible hydrogen storage, highlighting the role of transition-metal centers in tuning adsorption properties.</p>

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Scandium-decorated pillar[5]arene for hydrogen storage: from weak physisorption to enhanced molecular adsorption

  • 期刊论文

  • 发表日期：

    2026年5月12日

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  • Ridha Ben Said

摘要

The interaction of molecular hydrogen with pristine and Sc-decorated pillar[5]arene (P5) was investigated using density functional theory to elucidate the mechanisms governing hydrogen adsorption. The pristine macrocycle exhibits very weak physisorption, with negligible interaction strength and no activation of the H–H bond. In contrast, scandium decoration introduces well-defined adsorption sites and significantly enhances hydrogen binding. The fully decorated 5Sc–P5 system shows adsorption energies in the range of − 0.163 to − 0.380 eV per H₂ molecule, accompanied by moderate H–H bond elongation. Electronic structure analysis (PDOS and IGMH) reveals clear hybridization between H 1s and Sc 3d orbitals, consistent with a Kubas-type interaction mechanism involving σ-donation and back-donation. Thermodynamic analysis based on a grand canonical approach predicts a maximum hydrogen uptake of 25 H₂ molecules (6.2 wt%), with a practical reversible capacity of 5.2 wt% under near-ambient conditions (30 bar, 298 K / 3 bar, 373 K). These results demonstrate that scandium functionalization effectively transforms pillar[5]arene into a promising host for reversible hydrogen storage, highlighting the role of transition-metal centers in tuning adsorption properties.