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The electronic state of carbon in the products of co-carbonization of an aromatic heavy oil and ferrocene in an autoclave has been studied by X-ray emission spectroscopy. Analysis of the C Kα-spectra revealed that the proportion of graphite-like component in the samples containing ferric spherical and tubular nanoparticles is about 55% and 65%, respectively. An average size of graphitic sheets forming the coating on metallic cores and the carbon matrix was estimated by the results of quantum-chemical calculations on graphene fragments to be ∼2 nm. The field electron emission properties of the studied carbon materials were found to be dependent on the graphitization degree, not on the aspect ratio of constituting nanoparticles.

Calcium tartrate doped with Ni and/or Co has been used as a catalyst source in the chemical vapor deposition synthesis of carbon nanotubes (CNTs). Thermolysis of doped calcium tartrate in an inert atmosphere was shown to yield Ni, Co or Ni–Co nanoparticles ∼6 nm in diameter dispersed in a calcium oxide matrix. The CNT synthesis was carried out by ethanol vapor decomposition at 800 °C. The structure of the products was characterized by transmission electron microscopy and Raman spectroscopy. It was found that Ni nanoparticles embedded in CaO provide the narrowest diameter distribution of CNTs, while the bimetallic Ni–Co catalyst allows the formation of the thinnest CNTs with the outer diameter of ∼2 nm. This type of CNT is more likely to be responsible for the lowest value of the turn-on field (∼1.8 V/μm) for the emission current detected for the latter sample.

Nitrogen-doped carbon (CNx) nanotubes have been synthesized by acetonitrile vapor decomposition over catalyst nanoparticles produced in the result of thermolysis of solid solutions of Fe and Ni bimaleates. X-ray photoelectron spectroscopy revealed the nitrogen content in CNx nanotubes grows from 0.4 to 1.2 at%, when Ni portion in catalyst increases. Nitrogen doping level of sample produced using bimaleates of Fe and Ni taken in a ratio of 7:3 is deviated from this dependence due to formation of two phases of metallic catalyst. N 1s-edge X-ray absorption spectra of samples showed three peaks, which by results of quantum-chemical calculation on nitrogen-containing carbon nanotube (CNT) model were assigned to pyridinic, graphitic, and molecular forms of nitrogen. Measurements of current–voltage characteristics of the samples found the electron emission threshold is reduced with amount of nitrogen incorporated into CNx nanotubes.

Multiwalled carbon nanotubes (CNTs) have been synthesized by chemical vapor deposition (CVD) from methane and carbon monoxide. The process was catalyzed by cobalt nanoparticles produced via pyrolysis of a solid solution between cobalt and calcium tartrates. The solid solution was characterized by x-ray diffraction, thermogravimetry, and chemical analysis. As shown by transmission electron microscopy, the introduction of water vapor during synthesis increases the CNT content of the resulting material. The field emission current-voltage behavior of the CNTs is shown to depend on CVD conditions.

The action of high-power neodymium laser pulses on organic dielectric liquids in the presence of a catalyst (ferrocene) leads to the formation of quasi-spherical nanodimensional carbon particles with a specific complicated structure. The obtained solutions exhibit the phenomenon of optical limiting for nanosecond pulses of the first and second harmonics of a neodymium laser.