The disclosed technology is a method of improving yield of carbon nanotubes (CNT) and carbon nanofibers (CNF) from catalytic chemical vapor deposition (CVD) of a carbon-containing gas (consisting of at least one hydrocarbon mixed with carbon dioxide). The technology utilizes catalytic particles supported by oxide powders or a flat substrate. The catalytic particles consist of at least one Group VIIIB metal (iron, cobalt, nickel) and/or one Group VB metal (molybdenum, tungsten, chromium). Common oxide powders are magnesium oxide, aluminum oxide, silicon(II) oxide, calcium oxide, titanium(II) oxide, and zirconium(II) oxide. An example of a flat substrate would be a silicon wafer, although the technology is not limited to application on silicon wafers.
According to the disclosure, the CNT and CNF are formed by exposing the catalytic particles to the aforementioned gases at high temperatures. In lieu of hydrocarbons and carbon dioxide, oxygencontaining gases may be used.
The technology has been prototyped and tested. Key test results are presented in the published patent application.
- Improved yield – When the mole ratio of gases is optimized, yield increases of up to 250% are possible.
- High quality products – Resulting CNT are of high purity and suitable for use in any CNT application.
- Flexibility for manufacture – Support material for catalyst can either be a powder or a flat surface.
- Reduced waste – Reduces amount of amorphous carbon produced as a byproduct.
- Improved catalyst life – Use of the optimal amount of carbon dioxide can increase the time of activity for the catalyst.
- Improved CNT properties – Greater crystallinity and elongated lengths of resulting CNT.
The technology is applicable in catalysis for producing CNT and CNF in a wide variety of application areas, including the following:
- Nanoscale electronic devices
- High strength materials
- Electron field emission
- Tips for scanning probe microscopy
- Solar cells
- Gas storage
- Fillers of polymers in any product where electrically conductive polymer films are needed
- Field emission devices
- Photovoltaic devices
For additional information on the patent application, please follow this link:
Keywords: carbon nanotubes, carbon nanofibers, manufacture of carbon nano, chemical vapor deposition, catalysis, catalytic
Inventors: Zhongrui Li, Yang Xu, Alexandru S. Biris