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The boom that nanotechnology has had over the last 3 decades is undeniable. Carbon nanostructured forms are mainly responsible for this interest in nanomaterials, since historically they paved the way to the study of nanomaterials with the discovery of fullerenes in 1985 and carbon nanotubes in 1991. Although there are various techniques to produce nanomaterials, chemical vapor deposition (CVD) is particularly valuable as it allows the production of a great variety of carbon nanostructures, it is versatile, scalable, easy to implement and of a relatively low-cost. This review article highlights the importance of CVD and details its principles, conditions and operation parameters, as well as the main variations of this technique. Detailed conditions are described for the production of fullerenes, nano-onions, carbon nanotubes, nanospheres, graphene, and others, emphasizing the specific parameters for each synthesis., Es innegable el auge que ha tenido la nanotecnología en las últimas tres décadas. Responsables de este interés en los nanomateriales son principalmente las formas nanoestructuradas del carbono, ya que históricamente fueron las que inauguraron el estudio de los nanomateriales con el descubrimiento de los fullerenos en 1985 y los nanotubos de carbono en 1991. Aunque existen diversas técnicas para producir estos materiales, la deposición química de vapores (CVD, por sus siglas en inglés) es particularmente valiosa, ya que permite la producción de una gran variedad de nanoestructuras de carbono, es versátil, escalable, de fácil implementación y de relativamente bajo costo. En este artículo de revisión se destaca la importancia de CVD y se detallan sus principios, condiciones y parámetros de operación, así como sus principales variantes. Se realiza una descripción de la técnica utilizada para producir fullerenos, nano-cebollas, nanotubos de carbono, nanoesferas, grafeno y otras, recalcando los parámetros específicos para cada síntesis.

Graphene has emerged as a promising material for infrared (IR) photodetectors and plasmonics. In this context, wafer scale epitaxial graphene on SiC is of great interest in a variety of applications in optics and nanoelectronics. Here we present IR reflectance spectroscopy of graphene grown epitaxially on the C-face of 6H-SiC over a broad optical range, from terahertz (THz) to mid-infrared (MIR). Contrary to the transmittance, reflectance measurements are not hampered by the transmission window of the substrate, and in particular by the SiC Reststrahlen band in the MIR. This allows us to present IR reflectance data exhibiting a continuous evolution from the regime of intraband to interband charge carrier transitions. A consistent and simultaneous analysis of the contributions from both transitions to the optical response yields precise information on the carrier dynamics and the number of layers. The properties of the graphene layers derived from IR reflection spectroscopy are corroborated by other techniques (micro-Raman and X-ray photoelectron spectroscopies, transport measurements). Moreover, we also present MIR microscopy mapping, showing that spatially-resolved information can be gathered, giving indications on the sample homogeneity. Our work paves the way for a still scarcely explored field of epitaxial graphene-based THz and MIR optical devices.

Due to the need of integrated circuit in the current silicon technology, the formation of graphene on Si wafer is highly desirable, but is still a challenge for the scientific community. In this context, we report the direct growth of graphene on Si(111) wafer under appropriate conditions using an electron beam evaporator. The structural quality of the material is investigated in detail by reflection high energy electron diffraction, Auger electron spectroscopy, X-ray photoemission spectroscopy, Raman spectroscopy, high resolution scanning electron microscopy, atomic force microscopy, and scanning tunneling microscopy. Our experimental results confirm that the quality of graphene is strongly dependent on the growth time during carbon atoms deposition.

Here the authors report the use of either furnace heating or Joule heating to pacify the exposed graphene edges by loop formation in a novel graphitic nanoribbonmaterial, grown by chemical vapor deposition. The edge energy minimization process involves the formation of loops between adjacent graphene layers within the nanoribbons. A comparison is made of the similarities and differences between the loop structures formed using these two methods. An estimation of the temperature of these graphitic nanoribbons during Joule heating is also reported based on the melting and evaporation of Pt nanoparticles., National Science Foundation (U.S.) (Grant NIRT CTS-05-06830), National Science Foundation (U.S.) (Grant DMR 07-04197), MIT-CONACYT Collaboration Grant

An original and easy route to produce mono-, bi- and tri-layer graphene is proposed using the chemical vapor deposition technique. The synthesis is carried out at atmospheric pressure using liquid precursors, copper as catalyst, and a single gas injection line consisting of a very diluted mixture of H2 in Argon (H2: 5%). Two different alcohols are investigated as possible sources of carbon: 2-phenylethanol and ethanol. The characterization of the samples with SEM, TEM and Raman spectroscopy confirms the presence of graphene on top of copper, and yields a detailed picture of the structure of the produced graphene layers.

Chemical vapor deposition (CVD) represents an attractive route to synthesize large-area graphene. Its catalytic growth using metals has been studied in recent years, the most popular being nickel and copper. We have successfully grown graphene on copper by CVD at ambient pressure using alcohols as the carbon feedstock. The produced materials are analyzed by SEM, TEM, Raman spectroscopy and transferred onto Si/SiO2 substrates using standard methods. Raman fingerprint of monolayer graphene is present in our samples. This technique represents a safer and more versatile alternative to the production of graphene compared to the synthesis of graphene using methane at low pressure.

Graphene optical properties were first investigated with the motivation to maximize its visibility on various substrates [1], so that graphene flakes could easily be located and then patterned to fabricate electronic devices. But a few key experiments revealed that there was much more to expect from this research area, and, today, one can already state that graphene optical properties offer perspectives for various applications in the near future [2]. Recent experiments demonstrated that a gate voltage could tune graphene reflectance and transmittance, particularly in the infrared (IR) range [3]. This tunability was found to stem from strong changes in the Drude component of the optical conductivity, particularly important in the far-IR, and from gate-induced shift of interband transitions, governed by a peculiar threshold at 2EF in graphene (where EF is the Fermi energy).

The electronic structure and spin magnetism for few-layer-graphene nanoribbons synthesized by chemical vapor deposition have been investigated using near-edge x-ray absorption fine structure (NEXAFS) and electron-spin resonance (ESR). For the pristine sample, a prepeak was observed below the π∗ peak close to the Fermi level in NEXAFS, indicating the presence of additional electronic states close to the Fermi level. The intensity of this prepeak decreased with increasing annealing temperature and disappeared after annealing above 1500 °C. The ESR spectra, which proved the presence of localized spins, tracked the annealing-temperature-dependent behavior of the prepeak with fidelity. The NEXAFS and ESR results jointly confirm the existence of a magnetic edge state that originates from open nanographene edges. The disappearance of the edge state after annealing at higher temperatures is explained by the decrease in the population of open edges owing to loop formation of adjacent graphene edges., Japan. Ministry of Education, Culture, Sports, Science and Technology (MEXT) (Grant No. 20001006)

The electronic structure and spin magnetism for few-layer-graphene nanoribbons synthesized by chemical vapor deposition have been investigated using near-edge x-ray absorption fine structure (NEXAFS) and electron-spin resonance (ESR). For the pristine sample, a prepeak was observed below the pi* peak close to the Fermi level in NEXAFS, indicating the presence of additional electronic states close to the Fermi level. The intensity of this prepeak decreased with increasing annealing temperature and disappeared after annealing above 1500 degrees C. The ESR spectra, which proved the presence of localized spins, tracked the annealing-temperature-dependent behavior of the prepeak with fidelity. The NEXAFS and ESR results jointly confirm the existence of a magnetic edge state that originates from open nanographene edges. The disappearance of the edge state after annealing at higher temperatures is explained by the decrease in the population of open edges owing to loop formation of adjacent graphene edges.

Carbon is a unique and very versatile element which is capable of forming different architectures at the nanoscale. Over the last 20 years, new members of the carbon nanostructure family arose, and more are coming. This review provides a brief overview on carbon nanostructures ranging from C60 to graphene, passing through carbon nanotubes. It provides the reader with important definitions in carbon nanoscience and concentrates on novel one- and two-dimensional layered carbon (sp2 hybridized), including graphene and nanoribbons. This account presents the latest advances in their synthesis and characterization, and discusses new perspectives of tailoring their electronic, chemical, mechanical and magnetic properties based on defect control engineering. It is foreseen that some of the structures discussed in the review will have important applications in areas related to electronics, spintronics, composites, medicine and many others.

We study the role of ethanol in the thermolytic synthesis of multiwalled carbon nanotubes. We show that low concentrations of ethanol control the length and diameter, as well as the crystalline quality of the produced nanotubes. We statistically evaluated the dimensions of the tubes as the concentration of ethanol is increased. The quality of the samples results in more crystalline products when low concentrations of ethanol (∼1–2%) are used in the experiments. In addition, the introduction of ethanol during the synthesis seems to incorporate coordination groups on the surface of nanotubes that cause an enhanced reactivity and a better solubility.