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Abstract: We explore the defect formation on single‐layer graphene partially suspended over a microcavity upon etching by a focused electron beam in a reactive oxygen atmosphere. The formation of oxygenated defects in an area of several μm2 around the cut is studied by Raman spectroscopy. The narrow symmetric Raman D band has the same bandwidth as the G band line width of supported graphene. For suspended graphene, the D bandwidth is larger. From the ratio of the intensity of the Raman D and D′ band (ID/ID′), it is concluded that mainly sp3‐type defects are formed on supported graphene and more defects with a different spectral signature are formed on suspended graphene. Annealing in reductive H2/Ar atmosphere is found to remove bonded oxygen on supported graphene, whereas on suspended graphene with higher density of defects, defects are removed only partially. [ABSTRACT FROM AUTHOR]

The development of new synthetic methods is paramount for the versatile production of complex multicomponent electrodes for supercapacitors with enhanced performance. The reactive inverse matrix assisted pulsed laser evaporation (RIMAPLE) technique shows promise for the deposition of complex functional nanocomposites in a facile way. In this work, hybrid supercapacitor electrodes constituted by reduced graphene oxide (rGO) and carbon nanotubes (CNTs) decorated with a myriad of cerium and manganese oxide nanoparticles were obtained by using GO sheets, CNTs, CeO 2 nanoparticles and, for the first time, the (NH 4) 2 [Mn 2 (C 6 H 5 O 7) 2 (H 2 O) 2 ] coordination compound as precursors in the RIMAPLE targets. Compositional and structural characterizations revealed that post-annealing treatments at mild conditions (150-250 °C) induce a further reduction of the rGO and CNTs, besides an oxidation of the Ce oxide phases (Ce3+ to Ce4+) and a reduction of the Mn oxides (Mn3+ to Mn2+). The substantial change of the carbon and metal oxide nanostructures causes an up to 8-fold increase of the capacitance of the electrodes (63 F/cm3 @ 10 mV/s). Finally, the generation of a high quantity of edge defects at 250 °C and long dwell time leads to the drop of the electrode's capacitance. [ABSTRACT FROM AUTHOR]

The interaction energy for two adjacent adamantane molecules and that of adamantane molecules encapsulated inside carbon nanotubes are investigated considering only dipole-dipole induced interaction. The Lennard-Jones potential and the continuous approximation are utilised to derive analytical expressions for these interaction energies. The equilibrium distance 3.281 Å between two adamantane molecules is determined. The smallest carbon nanotube radius b 0 that can encapsulate the adamantane molecule and the radius of the tube b max that gives the maximum suction energy, linearly depend on the adamantane radius, are calculated. For larger diameter tubes, the off axis position has been calculated, and equilibrium distance between molecule and tube wall is found to be close to the interlayer spacing in graphene. [ABSTRACT FROM AUTHOR]

The covalent functionalization of single and bilayer graphene on SiO2 (300 nm)/Si was effected through sequential treatment with the alkalide reductant [K(15-crown-5)2]Na and electrophilic aryl or alkyl halides, of which the iodides proved to be the most reactive. The condensation reactions proceeded at room temperature and afforded the corresponding aryl- or alkyl-appended graphenes. For each sample, Raman and X-ray photoelectron spectroscopies were used to evaluate the degrees and uniformities of functionalization. Statistical analyses of the Raman data revealed that the introduction of the organic moieties was accompanied by sp³-rehybridization of the basal plane atoms. When bilayers consisting of 13C and 12C layers were treated, both the top and bottom sheets were decorated with organic groups. The reaction was followed using Raman spectroscopy, and the mechanism was studied by theoretical calculations. Indicative of its structure and reactivity, 4-pyridyl-decorated single-layer graphene was readily benzylated and appears to be an ideal platform to develop functional materials. [ABSTRACT FROM AUTHOR]

Raman spectra of large graphene bubbles showed size-dependent oscillations in spectral intensity and frequency, which originate from optical standing waves formed in the vicinity of the graphene surface. At a high laser power, local heating can lead to oscillations in the Raman frequency and also create a temperature gradient in the bubble. Based on Raman data, the temperature distribution within the graphene bubble was calculated, and it is shown that the heating effect of the laser is reduced when moving from the center of a bubble to its edge. By studying graphene bubbles, both the thermal conductivity and chemical reactivity of graphene were assessed. When exposed to hydrogen plasma, areas with bubbles are found to be more reactive than flat graphene. [ABSTRACT FROM AUTHOR]