Hydrogen on silicene: like or unlike graphene?

Abstract

Hydrogenation of free-standing silicene, the two-dimensional allotrope of silicon, is investigated in detail using first-principles methods and compared with the adsorption of H atoms on graphene. Similarly to graphene, chemisorption of a single H atom on silicene induces the formation of a semilocalized state around the adatom, a sharp peak in the density of states at the Fermi level which acts as a strong resonant scatterer for charge carriers. This state hosts an unpaired electron, the itinerant electron of the resonating valence bond picture which primarily resides on the "majority" sublattice and biases the reactivity towards specific lattice positions. Contrary to graphene, sticking of hydrogen atoms is barrierless, on both the pristine and the hydrogenated surface. As a consequence, hydrogen adsorption on silicene is expected to proceed randomly under typical laboratory conditions, and preferential binding to form balanced dimers (or clusters) only occurs when thermodynamic equilibrium conditions prevail. The absence of clustering can be experimentally confirmed using scanning tunneling microscopy techniques since simulated imaging shows that the investigated structures provide distinguishable features that should allow their easy identification, if present on the surface. Overall, our findings can be rationalized by the fact that in silicene π bonds are weaker and the lattice is softer than in graphene and suggest that in silicene adatoms may severely limit carrier mobility.

Spin-polarized electric current in silicene nanoribbons induced by atomic adsorption

“…30 Moreover, chemisorption of a single H atom on silicene induces the formation of a localized state around the adatom which acts as a resonant scatterer for charge carriers. 31 Hence, a significant reduction of the electron mobility is anticipated since the absence of clustering prevents the conversion of isolated adatoms into clusters, which are known to have a much smaller effect on electron mobility. 31 Theoretical methods and modeling are needed to understand the role of adatoms in the electron transport of silicene and their influence on the spin filtering capabilities induced by the proximity exchange interaction.…”

“…31 Hence, a significant reduction of the electron mobility is anticipated since the absence of clustering prevents the conversion of isolated adatoms into clusters, which are known to have a much smaller effect on electron mobility. 31 Theoretical methods and modeling are needed to understand the role of adatoms in the electron transport of silicene and their influence on the spin filtering capabilities induced by the proximity exchange interaction. In this paper we address the effects of a random distribution of adatoms on the electron transport properties of narrow silicene nanoribbons.…”

Electronic and Magnetic Properties of Two-dimensional Nanomaterials beyond Graphene and Their Gas Sensing Applications: Silicene, Germanene, and Boron Carbide

“…The buckling distance of both structures is found to be 0.71 Å. These values agree with previous findings for hydrogenated silicene [371,373,378,381,382,385]. In order to find the favored coupling of the magnetic moments, three different It is worth mentioning that for non-hydrogenated flakes, experimentally, both Si A and Si B atoms would be exposed to hydrogen atoms.…”

“…Hydrogenation was found as a favorable chemical method to modify the electronic and magnetic properties of graphene because of its reversibility [33] and controllability [369,370]. There has been quite a number of theoretical [45,87,127,306,[371][372][373][374][375][376][377][378][379][380][381][382][383][384][385] and experimental [123,125,126] studies on the hydrogenation of silicene in the literature. Intriguing properties in hydrogenated silicene have been reported through theoretical calculations, for example, large gap opening [45], and extraordinary FM [372] and optoelectronic properties [127].…”

Dual-Route Hydrogenation of the Graphene/Ni Interface

“…28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 grid has been superimposed on top of the STM image, the protrusions are mostly small structures (white circles) accompanied by few elongated (green ellipses) and rare round-like (blue circles) features. By comparison with the STM images taken on hydrogenated graphite and Gr/SiC(0001) surfaces 33,34 and simulated for H/Gr, 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 the Ni substrate, 13,…”