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Hydrogen intercalation of CVD graphene on Germanium (001) – strain and doping analysis using Raman spectroscopy
摘要： We report a study of structural properties of graphene grown on germanium (001) when subjected to hydrogen intercalation during cooling, using chemical vapor deposition method. The systematic statistical analysis of the Raman spectra indicated that hydrogen increased the number of structural defects in graphene and caused the increase of the compressive strain. Interestingly, it was also found that hydrogen impacted on charge doping. This findings offer a new insight into the nature of graphene-germanium interaction and constitutes an important step towards graphene integration into modern electronics.
关键词： hydrogen intercalation,raman spectroscopy,graphene on germanium
更新于2025-09-04 15:30:14
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Band Gap Width Control by Cu Intercalation into ZrSe <sub/>2</sub>
摘要： The CuxZrSe2 intercalation single crystals have been synthesized and studied in a concentration range of x = 0 – 0.3, in which the semiconductor-metal transition was observed. The evolution of the electronic structure of CuxZrSe2 as a function of the copper content has been studied experimentally using the XPS and XAS methods. The obtained results indicate the gradual shift of the Fermi level with increasing copper content, which does not allow the metal-insulator transition to be associated with charge transfer to the conduction band. This transition is associated with the formation of the covalent bond between copper and the nearest selenium atoms and of the p-d hybridized states inside the Zr 4d/Se 4p band gap. First-principle calculations were performed in order to obtain a theoretical description of the density of states near the Fermi level and confirm this conclusion.
关键词： first-principle calculations,covalent bond,Fermi level,CuxZrSe2,semiconductor-metal transition,XPS,XAS,p-d hybridized states,intercalation,electronic structure
更新于2025-09-04 15:30:14
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Photosensitive carbon supercapacitor: Cavitated nanoporous carbon from iodine doped β–cyclodextryn
摘要： We have discovered a giant enhancement of the supercapacity (up to 4 times) under sun illumination of electrodes fabricated from cavitated nanoporous carbon being carbonized from a iodine doped β–cyclodexryn. This effect was achieved even without a frequently used KOH treatment and is caused by enhancement of effective activated surfaces. The synthesized cavitated nanoporous carbon exhibits principally different accumulative features at the carbon/electrolyte interface. Relationship between the porous structure, electronic properties of supramolecular nanoporous carbon and enhanced supercapacitance is explored. The impedance spectroscopy measurements (Nyquist diagram) apparently suggest a capacitance mechanism for the energy accumulation. Enhancement of the supercapacity is explained by light-generated carriers in low-dimensional nano-interfaces. In relevant mechanism an increasing concentration of delocalized electrons results in unlocking of the Helmholtz layer capacity.
关键词： nanoporous carbon,Nyquist diagrams,intercalation,Porous structures,pseudocapacity
更新于2025-09-04 15:30:14
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Incipient Anion Intercalation of HOPG Close to the Oxygen Evolution Potential. A Combined X-ray Photoemission and Raman Spectroscopy Study
摘要： In the present work we used two different electrochemical (EC) techniques, namely cyclic voltammetry (CV) and normal pulsed voltammetry (NPV), applied to a highly oriented pyrolytic graphite (HOPG) electrode for anion intercalation in two different aqueous electrolytes (i.e. perchloric and sulphuric acid). We performed comparative X-ray photoemission (XPS) and Raman spectroscopy studies at various EC potentials. The chemical analysis obtained by XPS and Raman, the latter applied in-situ and in real-time during the electrochemical processes, indicates that at oxygen evolution potential (i.e. before reaching the well-known intercalation stage potentials) the HOPG intercalation process is already active. These results suggest that the intercalated compound is efficiently obtained before reaching higher potentials, which usually cause a detriment of the graphite crystal.
关键词： HOPG,Raman spectroscopy,X-ray photoemission,anion intercalation,normal pulsed voltammetry,cyclic voltammetry
更新于2025-09-04 15:30:14
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Reversible and selective ion intercalation through the top surface of few-layer MoS2
摘要： Electrochemical intercalation of ions into the van der Waals gap of two-dimensional (2D) layered materials is a promising low-temperature synthesis strategy to tune their physical and chemical properties. It is widely believed that ions prefer intercalation into the van der Waals gap through the edges of the 2D flake, which generally causes wrinkling and distortion. Here we demonstrate that the ions can also intercalate through the top surface of few-layer MoS2 and this type of intercalation is more reversible and stable compared to the intercalation through the edges. Density functional theory calculations show that this intercalation is enabled by the existence of natural defects in exfoliated MoS2 flakes. Furthermore, we reveal that sealed-edge MoS2 allows intercalation of small alkali metal ions (e.g., Li+ and Na+) and rejects large ions (e.g., K+). These findings imply potential applications in developing functional 2D-material-based devices with high tunability and ion selectivity.
关键词： defects,MoS2,electrochemical control,two-dimensional materials,ion intercalation
更新于2025-09-04 15:30:14