Ordered and Reversible Hydrogenation of Silicene

Abstract

The hydrogenation of monatomic silicene sheet on Ag(111) was studied by scanning tunneling microscopy and density functional theory calculations. It was observed that hydrogenation of silicene at room temperature results in a perfectly ordered γ-(3×3) superstructure. A theoretical model, which involves seven H atoms and rearranged buckling of Si atoms, was proposed and agrees with experiments very well. Moreover, by annealing to a moderate temperature, about 450 K, a dehydrogenation process occurs and the clean silicene surface can be fully recovered. Such uniformly ordered and reversible hydrogenation may be useful for tuning the properties of silicene as well as for controllable hydrogen storage.

Dumbbell stanane: a large-gap quantum spin hall insulator

“…The 2×2 superstructure of germanene grown an Al(111) substrate resemble the DB germanene very well 48 . Hydrogenation of silicene has also been achieved in a recent Qiu et al 49 ,…”

Hydrogen-induced sp2−sp3 rehybridization in epitaxial silicene

“…As a result, in one half six Si atoms are up-buckled and saturated by H and in the other half only one Si atom is * dmytro.solonenko@physik.tu-chemnitz.de up-buckled and saturated by H [see Fig. 3(d)] [15]. Such a reconstruction is only observed after hydrogenation.…”

“…The reported STM images show that the atomic structure of hydrogenated epitaxial silicene [15,16] differ from the one expected for silicane, while hydrogen exposure results in a rearrangement of the silicene lattice in a predominantly ordered fashion, yielding the formation of so-called hydrogenated γ -silicene [15]. This γ phase has a unit cell based on the unit cell of (3 × 3)/(4 × 4) silicene, where the buckling direction between the two triangular halves changes.…”

“…Due to the asymmetry of its unit cell, it loosely resembles another pristine silicene phase, a so-called β-silicene, which forms on Ag(111) and can be explained by three horizontal Si planes, separated by the buckling distance [17]. Besides the γ phase, another H-silicene phase is reported, where the unit cell is symmetrically hydrogenated, termed α-silicene [15,16]. In this phase, H adsorbs directly at the six up-buckled Si atoms of the symmetric (3 × 3)/(4 × 4) unit cell [see Fig.…”

“…Although hydrogenation of epitaxial silicene is experimentally feasible due to its high chemical reactivity [14], the experimental investigation of hydrogenated silicene are scarce, except studies by scanning tunneling microscopy (STM) [15,16] and high-resolution electron-energy-loss spectroscopy [16]. The reported STM images show that the atomic structure of hydrogenated epitaxial silicene [15,16] differ from the one expected for silicane, while hydrogen exposure results in a rearrangement of the silicene lattice in a predominantly ordered fashion, yielding the formation of so-called hydrogenated γ -silicene [15].…”