Raman spectroscopy on hydrogenated graphene under high pressure. (January 2020)

• Record Type: Journal Article
• Authors: Pakornchote, Teerachote; Geballe, Zachary M.; Pinsook, Udomsilp; Taychatanapat, Thiti; Busayaporn, Wutthikrai; Bovornratanaraks, Thiti; Goncharov, Alexander F.
• Is Part Of: Carbon. Volume 156(2020)
• Page Start: 549
• Page End: 557
• Publication Date: 2020-01
• Subjects: Hydrogenated graphene -- Graphane -- High pressure -- Thermodynamic pathway -- Raman spectroscopy; Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2019.09.077
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: We applied laser-heating in diamond anvil cells (LHDAC) to synthesize a hydrogenated single-layer graphene (SLG) and to explore the pathway toward graphane (fully hydrogenated SLG). We employed Raman spectroscopy to investigate SLG on a Cu substrate that was compressed up to 8 GPa and 20 GPa with 2.2% and 4.6% compressive strain, respectively, followed by laser-heating. After laser-heating, G and 2D peaks exhibit a redshift, and then form a hysteresis loop during decompression. This phenomenon can be due to either of two mechanisms, or both; the formation of C–H chemical bonds in massive hydrogenated SLG, and a reduction of the frictional stress between SLG and Cu substrate causing a relaxation of SLG lattice toward its free-standing equilibrium structure. The correlation between G and 2 D peaks also changes significantly after laser-heating at 8 GPa, resembling the correlation measured in hole-doping experiments. Finally, residual hydrogen remains bonded to the graphene layer after decompression to ambient pressure, and the amount of hydrogen increases as a function of pressure at which the sample was laser-heated. Graphical abstract: Image 1