Synthesis of high quality carbon single-walled nanotubes
AssigneeHonda Motor Co., Ltd.
InventorsAvetik R. Harutyunyan, Oleg Kuznetsov
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Abstract
Methods and processes for synthesizing high quality carbon single-walled nanotubes (SWNTs) are provided. A carbon precursor gas at reduced concentration (pressure) is contacted with a catalyst deposited on a support and at temperature about 10° C. above the SWNT synthesis onset temperature, but below the thermal decomposition temperature of the carbon precursor gas for given growth conditions. The concentration (pressure) of the carbon precursor gas can be controlled by reducing the total pressure of the gas, or by diluting with an inert carrier gas, or both. The methods produce SWNTs with the ratio of G-band to D-band in Raman spectra (IG:ID) of about 5 to about 200.
Claims7
A method for synthesizing carbon single-walled nanotubes (SWNTs), the method comprising:
- providing a supported metal catalyst and a carbon precursor gas,
- wherein the carbon precursor gas has a first SWNT synthesis onset temperature
- when contacted with the supported metal catalyst at a pressure of 780 Torr,
- wherein the carbon precursor gas has a second SWNT synthesis onset temperature when contacted with the supported metal catalyst at a pressure of less than 780 Torr, and
- wherein the second SWNT synthesis temperature is greater than the first SWNT synthesis onset temperature;
- and
- contacting the supported metal catalyst with a reaction gas at a temperature that is at or above the second SWNT synthesis onset temperature and less than a thermal decomposition temperature of the carbon precursor gas,
- wherein the reaction gas comprises the carbon precursor gas and optionally one or more inert gases,
- wherein the carbon precursor gas is methane,
- wherein the first SWNT synthesis onset temperature is 760° C.,
- wherein the second SWNT synthesis onset temperature is greater than 800° C., and
- wherein the partial pressure of the carbon precursor gas is less than 180 Torr.
Dependencies are inferred from the claim text.