Amorphous Carbon Impurities Play an Active Role in Redox Processes of Carbon Nanotubes

2011 ◽  
Vol 115 (51) ◽  
pp. 25281-25284 ◽  
Author(s):  
Adriano Ambrosi ◽  
Martin Pumera
Keyword(s):  
Carbon Nanotubes ◽  
Amorphous Carbon ◽  
Active Role ◽  
Redox Processes ◽  
Carbon Impurities

A Hierarchical Approach to Purify and Functionalize Pristine Carbon Nanotubes

2012 ◽  
Vol 510-511 ◽  
pp. 118-123
Author(s):  
M. Mansoor
Keyword(s):  
Carbon Nanotubes ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Wet Oxidation ◽  
Hierarchical Approach ◽  
Experimental Conditions ◽  
Aspect Ratios ◽  
Carbon Impurities ◽  
Metallic Catalyst ◽  
Surfactant Assisted

A step-by-step, hierarchical approach is explored in the present work to purify and functionalize carbon nanotubes synthesized by chemical vapor deposition. Attempts are made to purify and functionalize CNTs without extinguishing their aspect ratios. The carbon impurities are removed by thermal oxidation, whilst the unprotected metallic catalyst particles are eliminated by wet oxidation, subsequently; CNT bundles are de-roped by surfactant assisted sonication. Finally, protected metallic catalyst particles are removed and functional groups (hydroxyl and carboxyl) are attached by acid treatment and wet oxidation, respectively. The derivate CNTs are characterized using zeta potential measurements, TGA, XRD, FTIR and SEM. The characterization showed that in optimum experimental conditions the catalytic particles are removed upto 80%, the carbon impurities are eliminated upto 95% and chemical functionalities of hydroxyl and carboxyl is occurred with noticeable de-roping of the CNT bundles.

Opposite effects of self-growth amorphous carbon and carbon nanotubes on the reforming of toluene with Ni/α-Al 2 O 3 for hydrogen production

2017 ◽  
Vol 42 (21) ◽  
pp. 14439-14448 ◽  
Author(s):  
Limo He ◽  
Song Hu ◽  
Long Jiang ◽  
Syed Shatir A. Syed-Hassan ◽  
Yi Wang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Production ◽  
Amorphous Carbon

Preferential Growth of Carbon Nanotubes/Nanofibers Using Lithographically Patterned Catalysts

2001 ◽  
Vol 675 ◽  
Author(s):  
K. B. K. Teo ◽  
M. Chhowalla ◽  
G. A. J. Amaratunga ◽  
W. I. Milne ◽  
G. Pirio ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Amorphous Carbon ◽  
Deposition Process ◽  
High Yield ◽  
Full Potential ◽  
Carbon Nanofibres ◽  
Preferential Growth ◽  
Plasma Decomposition

ABSTRACTIn order to utilise the full potential of carbon nanotubes/nanofibers, it is necessary to be able to synthesize well aligned nanotubes/nanofibres at desired locations on a substrate. This paper examines the preferential growth of aligned carbon nanofibres by PECVD using lithographically patterned catalysts. In the PECVD deposition process, amorphous carbon is deposited together with the nanotubes due to the plasma decomposition of the carbon feed gas, in this case, acetylene. The challenge is to uniformly nucleate nanotubes and reduce the unwanted amorphous carbon on both the patterned and unpatterned areas. An etching gas (ammonia) is thus also incorporated into the PECVD process and by appropriately balancing the acetylene to ammonia ratio, conditions are obtained where no unwanted amorphous carbon is deposited. In this paper, we demonstrate high yield, uniform, ‘clean’ and preferential growth of vertically aligned nanotubes using PECVD.

Low temperature growth of carbon nanotubes on tetrahedral amorphous carbon using Fe–Cu catalyst

Carbon ◽  
2015 ◽  
Vol 81 ◽  
pp. 639-649 ◽  
Author(s):  
R. Cartwright ◽  
S. Esconjauregui ◽  
D. Hardeman ◽  
S. Bhardwaj ◽  
R. Weatherup ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Low Temperature ◽  
Amorphous Carbon ◽  
Temperature Growth ◽  
Low Temperature Growth ◽  
Tetrahedral Amorphous Carbon ◽  
Cu Catalyst

Spontaneous formation of carbon nanotubes and polyhedra from cesium and amorphous carbon

1998 ◽  
Vol 292 (3) ◽  
pp. 352-356 ◽  
Author(s):  
Mark G. Stevens ◽  
Shekhar Subramoney ◽  
Henry C. Foley
Keyword(s):  
Carbon Nanotubes ◽  
Amorphous Carbon ◽  
Spontaneous Formation

Growth of high-quality single-wall carbon nanotubes without amorphous carbon formation

2004 ◽  
Vol 84 (2) ◽  
pp. 269-271 ◽  
Author(s):  
R. G. Lacerda ◽  
A. S. Teh ◽  
M. H. Yang ◽  
K. B. K. Teo ◽  
N. L. Rupesinghe ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Amorphous Carbon ◽  
Single Wall Carbon Nanotubes ◽  
Carbon Formation ◽  
High Quality ◽  
Single Wall Carbon
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