Alkali Metal Arenides as a Universal Synthetic Tool for Layered 2D Germanene Modification

Abstract

The rediscovery of graphene in 2004 has started an enormous chase in the researchof2Dmaterials.Anew family of layered 2D materials consisting of the 14th group elements beyond carbon has already been reported. Here,anew methodology in germanene chemistry is presented using germanane (Ge 6 H 6 )a sastable and easily accessible starting material for effective synthesis of novel germanene derivatives. The modification procedure utilizing strong bases-alkali metal arenides-for deprotonation of germanane and its subsequent functionalization with p-nitrobenzyl bromide is described. Functionalization of germanene is confirmed by FT-IR, Raman, and XPS spectroscopya sw ell as by X-ray diffraction analysis. Figure 6. The TEM image of functionalized germananes ample.T he insert shows SAED image of flake and bottom image shows highresolution TEM image.

Two-Dimensional Functionalized Germananes as Photoelectrocatalysts

“…Hydrogen-terminated germanane (Ge-H) prepared by the reaction of CaGe 2 with cold concentrated HCl shows two major peaks at 2000 and ∼500 cm –1 , associated with Ge-H vibration. The peak at ∼500 cm –1 can be resolved into three components at 574, 502, and 475 cm –1 , all related to the Ge-H wagging vibrations. , The other peaks in the region below 900 cm –1 are associated with Ge-H 2 edge termination. Other functionalized germananes were prepared by a two-phase extraction procedure between an organic phase (alkyl halide) with CaGe 2 crystals and water.…”

“…The peak at ∼500 cm −1 can be resolved into three components at 574, 502, and 475 cm −1 , all related to the Ge-H wagging vibrations. 14,21 The other peaks in the region below 900 cm −1 are associated with Ge-H 2 edge termination. Other functionalized germananes were prepared by a two-phase extraction procedure between an organic phase (alkyl halide) with CaGe 2 crystals and water.…”

“…In turn, this has elicited the interest to gradually develop other synthetic and functionalization techniques, such as ionexchange, 18 solvothermal reaction, 19 deintercalation by hydrofluoric acid, 20 and deprotonation of germanene by alkali metal arenides such as sodium naphthalenide followed by alkylation for different modifications. 8,21 In particular, the alkylation approach utilizing n-alkyl halides or trifluoromethyl groupcontaining benzyl halides has emerged as a versatile technique that has created rich possibilities for the functionalization of germananes. 8,22 Presently, the intensive research has collectively produced germananes in more than 30 variants.…”

“…The single-step approach was innovated by employing methyl or other organic halides instead of the concentrated acid to transform CaGe 2 to germanene with methyl (methyl germanane, Ge-Me) and other organic group terminations. − In comparison to its hydrogen-terminated counterpart, these covalently functionalized germanenes revealed improved thermal stability, stronger photoluminescence in the red wavelength region, and tunable optical band gaps. − These encouraging outcomes have stimulated the possibility to alter the properties of 2D germanenes by rationally designed terminations, succeeding in the functionalization of graphene. In turn, this has elicited the interest to gradually develop other synthetic and functionalization techniques, such as ion-exchange, solvothermal reaction, deintercalation by hydrofluoric acid, and deprotonation of germanene by alkali metal arenides such as sodium naphthalenide followed by alkylation for different modifications. , In particular, the alkylation approach utilizing n -alkyl halides or trifluoromethyl group-containing benzyl halides has emerged as a versatile technique that has created rich possibilities for the functionalization of germananes. , …”

“…Presently, the intensive research has collectively produced germananes in more than 30 variants. ,− ,− The experimental investigations on various terminations have been thus far focused almost exclusively on their fundamental thermal stability and structural, vibrational, and optical properties. ,,,, Notably, the ligand strain and electronegativity of the organic ligands have disclosed a profound influence on the vibrational and electronic structures of functionalized germananes . Nevertheless, only a few works aimed at the practical applications of these functionalized germananes, and even so, those were concentrated on the −H and −CH 3 (Me) variants.…”