Graphene quantum dots (GQDs) have attracted significant interest as synthetically tunable optoelectronic and photonic materials that can also serve as model systems for understanding size-dependent behaviors of related graphene structures such as nanoribbons. We present a Raman spectroscopy study of bottom-up synthesized GQDs with lateral dimensions between 0.97 to 1.62 nm, well-defined (armchair) edge type, and fully benzenoid structures. For a better understanding of observed size-dependent trends, the study is extended to larger graphene structures including nano-graphene platelets (>25 nm) and large-area graphene. Raman spectra of GQDs reveal the presence of D and G bands, as well as higher order modes (2D, D + G, and 2G). The D and G band frequencies and intensity were found to increase as GQD size increases, while higher order modes (2D, D + G, and 2G) also increased in intensity and became more well-defined. The integrated intensity ratios of D and G bands (I_D/I_G) increase as the size of the GQDs approaches 2 nm and rapidly decrease for larger graphene structures. We present a quantitative comparison of I_D/I_G ratios for the GQDs and for defects introduced into large area graphenes through ion bombardment, for which inter-defect distances are comparable to the sizes of GQDs studied here. Close agreement suggests the I_D/I_G ratio as a size diagnostic for other nanographenes. Finally, we show that Raman spectroscopy is also a good diagnostic tool for monitoring the formation of bottom-up synthesized GQDs.

This brief review presents a comprehensive outline of the present research status on the fast moving carbon nanotube (CNT) field. It covers a short introduction to the relation between carbon nanotubes, graphite, and other forms of carbon and explains in detail the structure of CNTs. The electronic, electrical, and mechanical properties of CNTs, as well as the most widely used methods for CNT production such as electric arc discharge, laser ablation, and chemical vapor deposition (CVD), are discussed. Some of the CNT applications covered in this review article are: field emission, hydrogen storage, carbon nanotube-based solar cells, and CNT composite materials.

In this work, we report a low-cost facile method for the production of few-layer graphene sheets in large quantities through radio-frequency chemical vapor deposition.

High quality single-wall carbon nanotubes were synthesized on a MgO supported Fe-Co catalyst system using an inductive radio frequency catalytic chemical vapor deposition method with methane utilized as the hydrocarbon source. The synthesis temperature was varied between 700–1000 °C, and major differences when it comes to the size controllability of the catalyst nano-particles and the nanotube morphology were noticed when the reaction temperature was set at 800 and at 1000 °C. The structural and morphological properties of the catalyst system were analyzed by microscopy, X-ray diffraction and surface area analysis. The electron microscopy analyses of the catalyst system showed that the Fe/Co active metal nano-clusters have a very narrow size distribution when the catalyst system is thermally treated at 800 °C. As a result, highly crystalline single-wall carbon nanotubes with a narrow diameter distribution were successfully synthesized. It was found that by increasing the reaction temperature from 800 to 1000 °C, the diameter distribution of Fe/Co nano-particles broadens and hence affects the nanotube diameters. At 1000 °C the nanotubes presented a wider diameter distribution when compared to the ones grown at lower temperatures, a fact correlated to the changes in the catalyst structural morphology. Furthermore, the nanotubes synthesized at different reaction temperatures were analyzed using several techniques such as electron microscopy, thermogravimetric analysis, Raman and UV-Vis-NIR spectroscopy.

A novel method of transferring large-area graphene sheets onto a variety of substrates using Formvar (polyvinyl formal) is presented. Due to the ease at which formvar can be dissolved in chloroform this method allows for a consistent, a clean, and a more rapid transfer than other techniques including the PMMA assisted one. This novel transfer method is demonstrated by transferring large-area graphene onto a range of substrates including commercial TEM grids, silicon dioxide and glass. Raman spectroscopy was used to confirm the presence of graphene and characterize the morphological properties of the large-area sheets. SEM and AFM analyses demonstrated the effectiveness of our rapid transfer technique for clean crystalline large-area graphene sheets. The removal of the sacrificial polymer was found to be one to two orders of magnitude faster than PMMA methods. Ultimately this facile transfer technique offers new opportunities for a wide range of applications for large-area graphene through the utilization of a new sacrificial polymer.