Molecular Hydrogen Chemisorbed on Unsaturated Coordinate Ti: A New Designed Materials for Hydrogen Storage

Solid-state hydrogen storage materials with optimal binding energy are essential for hydrogen storage and transportation applications and pose long-standing challenges. Current technologies, including molecular physisorption materials (e.g., metal–organic frameworks (MOFs), carbon nanotubes (CNTs), activated carbons (ACs)) and atomic chemisorption materials (e.g., MgH₂, LiBH₄, NH₄BH₄), fall short of meeting practical application requirements. Therefore, designing and constructing new solid-state hydrogen storage materials at the atomic level is critically important. In this study, the use of defect engineering is explored to modulate hydrogen adsorption sites on TiO₂ surfaces. The results demonstrate that low-coordinated titanium (Ti) atoms on TiO₂ can serve as effective hydrogen adsorption sites, storing hydrogen through molecular chemisorption with significantly enhanced adsorption energy compared to Ti atoms in high coordination states. Moreover, the adsorbed hydrogen remains in molecular form, facilitating easy desorption at room temperature, unlike titanium hydride, which requires high temperatures for desorption. This approach provides a promising pathway for developing efficient hydrogen storage materials by leveraging the unique properties of low-coordinated Ti atoms on TiO₂ surfaces.