Carbon nanofiber

Carbon has a high level of chemical bonding flexibility, which lends itself to the formation of a number of stable Organic and Inorganic Molecules.

[citation needed] Catalytic chemical vapor deposition (CCVD) or simply CVD with variants like thermal and plasma-assisted is the dominant commercial technique for the fabrication of VGCF and VGCNF.

In the batch process developed by Tibbetts,[6] a mixture of hydrocarbon/hydrogen/helium was passed over a mullite (crystalline aluminum silicate) with fine iron catalyst particle deposits maintained at 1000 °C.

[8] This process typically yields VGCF with sub-micrometre diameters and lengths of a few to 100 μm, which accords with the definition of carbon nanofibers.

They utilized organometallic compounds dissolved in a volatile solvent like benzene that would yield a mixture of ultrafine catalyst particles (5–25 nm in diameter) in hydrocarbon gas as the temperature rose to 1100 °C.

The catalyst particle remains buried in the growth tip of the fiber at a final concentration of about a few parts per million.

While still an active area of research, there have been studies conducted that indicate health risks associated with carbon nanotubes (CNT) and CNF that pose greater hazards than their bulk counterparts.

One of the primary hazards of concern associated with CNT and CNF is respiratory damage such as pulmonary inflammation, granuloma, and fibrosis.

[13] A separate study conducted prior to the 2013 annual Society of Toxicology meeting aimed to identify potential carcinogenic effects associated with multi-walled carbon nanotubes (MWCNT).

This standard was based on information gathered from 14 sites whose samples were analyzed by transmission electron microscopy (TEM).

[14] A recent safety data sheet (SDS) for CNF (revised in 2016) lists the nanofibers as an eye irritant, and states that they have single exposure respiratory system organ toxicity.

The recommended personal protective equipment (PPE) for handling CNF includes nitrile gloves, particle respirators, and nanomaterial-impervious clothing (dependent on workplace conditions).

In the USA, the deeper studies focusing on synthesis and properties of these materials for advanced applications were led by R. Terry K.

In 1991, Japanese researchers Sumio Iijima, while working at NEC, synthesized hollow carbon molecules and determined their crystal structure.