Charging-assisted hydrogen release mechanism in layered boron hydride

We present a first-principles study of the dehydrogenation mechanism of a recently proposed layered boron hydride (B${}_{2}$H${}_{2}$) for hydrogen storage. The nudged elastic band method is employed to study the kinetic energy barrier against the release of hydrogen. Introducing additional charges into the B${}_{2}$H${}_{2}$ system reduces the electron deficiency of boron layer thereby lowering the dehydrogenation kinetic energy barrier. Finite-temperature molecular dynamics simulation further confirms the release of hydrogen atoms and the formation of molecular hydrogen upon charging the system. The boron network remains intact throughout the simulation up to at least 500 K. These results suggest a charging-assisted dehydrogenation mechanism in this system.