Influence of oxidation on hydrogen storage properties in titanium-based materials

Abstract

Hydrogen storage is essential for advancing clean energy technologies by enabling efficient energy storage and transport while reducing dependence on fossil fuels. This study explores the effects of oxidation on the hydrogen storage properties, bonding interactions, and electronic structure of hexagonal close-packed (hcp) titanium, with the goal of optimizing titanium-based materials for energy applications. To investigate the impact of oxidation, we analyze the stability of various interstitial sites in the hcp Ti lattice, evaluating their suitability for oxygen occupation and their influence on hydrogen storage characteristics. We compare the hydrogen storage capacities of pure hcp Ti and its oxidized form, (Ti2O). Bader analysis reveals that in both Ti2OH and Ti2H, the hydrogen atom receives a similar charge from Ti, but hydrogen release differs due to repulsive interactions between negatively charged oxygen and hydrogen, lowering the release temperature. In contrast, pure Ti, without oxygen, binds hydrogen more strongly, leading to a higher release temperature (780 K). Ti2O, with oxygen, releases hydrogen at 515 K, indicating that oxygen promotes easier hydrogen release compared to pure Ti. This study suggests that while oxidation reduces the hydrogen storage capacity of (Ti2O) relative to pure Ti, it lowers the hydrogen release temperature, making (Ti2O) more suitable for applications requiring lower release temperatures. Future research will focus on improving the properties of titanium-based materials to enhance hydrogen storage efficiency and enable controlled hydrogen release at lower temperatures, thus increasing their practical applicability. This work lays the foundation for further exploration of oxidized titanium compounds in hydrogen storage, with future efforts aimed at optimizing the structure and composition of these materials to address current challenges.