Hydrogen adsorption on germanene doped with Sn, V, Ti, Zn, and Cu and decorated with K, Li, and Mg. A DFT study

Hydrogen storage in germanene doped with transition metals (Cu, Sn, Ti, V, and Zn) and decorated with alkali or alkaline-earth metals (K, Li, and Mg) was investigated using first-principles calculations within the framework of Density Functional Theory. The results indicate that while metal doping tends to be energetically unfavorable, K-decoration provides strong and stable interactions with germanene. Among the systems explored, Mg-decorated germanene lacked the necessary properties for effective hydrogen storage. In contrast, Sn-K and Ti-Li decorated systems exhibited favorable adsorption energies, rapid desorption kinetics at near-room temperatures, and moderate formation energies, suggesting their experimental viability. To further assess the hydrogen release process, a kinetic temperature-programmed desorption (TPD) model was applied. The simulations revealed that hydrogen desorption in these systems occurs efficiently at temperatures close to ambient conditions, with fast desorption times. These findings identify Sn-doped/K-decorated and Ti-doped/Li-decorated germanene as promising candidates for reversible hydrogen storage applications. These findings highlight the potential of decorated germanene structures for practical energy storage technologies and emphasize the importance of careful selection of dopants and adatoms to optimize hydrogen adsorption and desorption properties. • Metal substitutions are energetically unfavorable. • Ti-Mg system exhibits optimal desorption properties, while Mg systems are unsuitable. • K-decorated systems show strong binding while Mg-decorated systems are unstable. • Sn-K and Ti-Li systems meet hydrogen storage conditions at 1–5 bar.