Beyond Kubas and anti-Kubas: an electrostatically driven pathway for quasi-molecular hydrogen adsorption in ribose and deoxyribose.

A comprehensive understanding of interaction mechanisms in the intermediate adsorption-energy regime relevant to hydrogen storage remains an important challenge in physical chemistry. This study employs density functional theory (DFT) calculations to investigate hydrogen adsorption on ribose and deoxyribose as representative polar molecular systems. The results reveal an adsorption behavior characterized by electrostatically induced polarization and dispersion interactions, accompanied by minimal charge transfer and negligible orbital hybridization. The corresponding adsorption energies fall within the quasi-molecular binding energy range. Detailed electronic-structure and real-space analyses indicate that the observed polarization originates from electronegative adsorption sites, providing an alternative route to quasi-molecular hydrogen adsorption in metal-free hydrogen storage materials. These findings provide molecular-level insight into hydrogen adsorption in polar systems and suggest a metal-free, polarization-driven anti-Kubas-like pathway for quasi-molecular hydrogen adsorption.