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Catalytic Growth of Carbon Nanotubes by Direct Liquid Injection CVD Using the Nanocluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)98-y(EtOH)y]

Department of Chemistry, Rice University, Houston, TX 77005, USA
Department of Materials Science and Nanoengineering, Rice University, Houston, TX 77005, USA
Energy Safety Research Institute, Swansea University Bay Campus, Swansea SA1 8EN, UK
Author to whom correspondence should be addressed.
Received: 8 January 2018 / Revised: 24 February 2018 / Accepted: 26 February 2018 / Published: 2 March 2018
(This article belongs to the Special Issue Carbon Nanotube and Applications)
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The growth of carbon nanotubes (CNTs) by direct liquid injection chemical vapor deposition (DLICVD) has been studied using the polyoxometalate cluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)98-y(EtOH)y] (FeMoC) as the catalyst with either ethanol or toluene as the carbon source. In order to screen different growth conditions a single large batch of FeMoC is required in order to eliminate variation in the catalyst precursor. The preparation of 6 g of FeMoC is possible by scaling (10×) literature reagent ratios. DLICVD studies of the FeMoC derived carbon product were evaluated by Raman spectroscopy and scanning electron microscopy (SEM) to determine the quality (G:D ratio) and purity of CNT content. With the use of ethanol as the carbon source, increasing the temperature in the injection zone (aspiration temperature) above 250 °C increases the yield, and results in a slight increase in the G:D ratio. The maximum yield is obtained with a growth temperature of 900 °C, while the G:D ratio is the highest at higher temperatures. Faster solution injection rates increase yield, but with a significant decrease in G:D, in fact no CNTs are observed in the product for the highest injection rate (10 mL/h). An optimum catalyst concentration of 1.25 wt.% is found, which influences both the catalyst:C and catalyst:H ratios within the system. Growth at 800 °C is far more efficient for toluene as a carbon source than ethanol. The resulting “process map” allows for large quantities of CNTs to be prepared by DLICVD. View Full-Text
Keywords: carbon nanotube; iron; molybdenum; nanocluster; CVD; direct liquid injection carbon nanotube; iron; molybdenum; nanocluster; CVD; direct liquid injection

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Esquenazi, G.L.; Brinson, B.; Barron, A.R. Catalytic Growth of Carbon Nanotubes by Direct Liquid Injection CVD Using the Nanocluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)98-y(EtOH)y]. C 2018, 4, 17.

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