Effect of Nitrogen and Hydrogen Gases on the Synthesis of Carbon Nanomaterials from Coal Waste Fly Ash as a Catalyst.

Various reducing and inert gases have been used in the catalytic chemical vapour deposition (CCVD) synthesis of carbon nanomaterials (CNMs). In this paper we report on the effects that hydrogen and nitrogen gases have on the production of CNMs from acetylene on fly ash catalysts. Parameters such as temperature and gas environments were investigated. Transmission electron microscopy (TEM) revealed that CNMs of various morphologies such as carbon nanofibers (CNFs) and carbon nanospheres (CNSs) were formed. When hydrogen was used the carbonaceous products were formed in higher yields as compared to when nitrogen was used. This could be due to the multifunctional roles that hydrogen plays as compared to nitrogen. Laser Raman and Mössbauer spectroscopy measurements revealed that three types of products were formed, namely: amorphous carbon, graphitic carbon and iron carbide. Significantly cementite (Fe3C) was identified as the main intermediate carbide species in the catalytic growth of well-ordered CNMs.

Direct synthesis of carbon nanofibers from South African coal fly ash.

Carbon nanofibers (CNFs), cylindrical nanostructures containing graphene, were synthesized directly from South African fly ash (a waste product formed during the combustion of coal). The CNFs (as well as other carbonaceous materials like carbon nanotubes (CNTs)) were produced by the catalytic chemical vapour deposition method (CCVD) in the presence of acetylene gas at temperatures ranging from 400°C to 700°C. The fly ash and its carbonaceous products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), laser Raman spectroscopy and Brunauer-Emmett-Teller (BET) surface area measurements. It was observed that as-received fly ash was capable of producing CNFs in high yield by CCVD, starting at a relatively low temperature of 400°C. Laser Raman spectra and TGA thermograms showed that the carbonaceous products which formed were mostly disordered. Small bundles of CNTs and CNFs observed by TEM and energy-dispersive spectroscopy (EDS) showed that the catalyst most likely responsible for CNF formation was iron in the form of cementite; X-ray diffraction (XRD) and Mössbauer spectroscopy confirmed these findings.

Tetraaqua-tetrakis-{µ(2)-[1-(carb-oxylato-meth-yl)cyclo-hex-yl]methanaminium}bis(µ(3)-hydroxido)bis(nitrato-κO,O')tetrazinc(II).

As the title gabapentin complex, [Zn(4)(OH)(2)(NO(3))(2)(C(9)H(17)NO(2))(4)(H(2)O)(4)](NO(3))(4) is located about a centre of inversion, the asymmetric unit contains two disordered nitrate ions and half a complex mol-ecule. The two zinc ions have different coordination environments: one is slightly distorted octa-hedral and the other is trigonal-pyramidal. The conformation of the gabapentin mol-ecule is defined by the formation of two intra-molecular O-H⋯O hydrogen bonds. Furthermore, the ammonium H atoms are involved in numerous hydrogen bonds with the disordered nitrate anions.

[1-(Carb-oxy-meth-yl)cyclo-hex-yl]methanaminium nitrate.

The title compound, C(9)H(18)NO(2) (+)·NO(3) (-), is an anhydrous nitrate salt of gabapentin, which is formed serendipitously in the presence of selected non-coordinating metals. The crystal structure involves extensive hydrogen bonding between the -NH(3) (+) and -COOH groups and the nitrate anion.

Composites of polyvinyl alcohol and carbon (coils, undoped and nitrogen doped multiwalled carbon nanotubes) as ethanol, methanol and toluene vapor sensors.

We investigate the chemical sensing behavior of composites prepared with polyvinyl alcohol and carbon materials (undoped multiwalled carbon nanotubes, nitrogen-doped multiwalled carbon nanotubes and carbon nanocoils). We determine the sensitivity of thin films of these composites for ethanol, methanol and toluene vapor, comparing their conductance and capacitance responses. The composite that exhibits highest sensitivity depends on specific vapor, vapor concentration and measured electrical response, showing that the interactivity of the carbon structure with chemical species depend on structural specificities of the carbon structure and doping.