Tailoring the germanene-substrate interactions by means of hydrogenation.

Thanks to density functional calculations, the influence of hydrogenation on the interactions between a (2 × 2) germanene layer and a (3 × 3) Al(111) substrate has been investigated. It appears that the Ge-Al inter-atomic distance increases with hydrogen coverage, while the interaction energy and charge transfer between the Ge layer and the Al topmost plane drastically diminish, thus reducing the electrostatic interactions. Moreover, hydrogenation also lowers the electron density at the interface, weakening the chemical interaction between the Ge layer and the Al surface, and opening the door to a possible decoupling of the germanene layer from the Al substrate.