Highly Consistent Atmospheric Pressure Synthesis of Carbon Nanotube Forests by Mitigation of Moisture Transients
Consistent synthesis of carbon nanotubes (CNTs) using laboratory-scale methods is essential to the development of commercial applications, particularly with respect to the verification of recipes that achieve control of CNT diameter, chirality, alignment, and density. Here, we report that transients...
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American Chemical Society (ACS)
2018
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| Online Access: | http://hdl.handle.net/1721.1/119379 https://orcid.org/0000-0003-4182-7533 https://orcid.org/0000-0002-7372-3512 |
| _version_ | 1811078253564133376 |
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| author | Polsen, Erik S. Li, Jinjing Bedewy, Mostafa White, Alvin Orbaek Tawfick, Sameh H. Hart, Anastasios John |
| author2 | Massachusetts Institute of Technology. Department of Mechanical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Mechanical Engineering Polsen, Erik S. Li, Jinjing Bedewy, Mostafa White, Alvin Orbaek Tawfick, Sameh H. Hart, Anastasios John |
| author_sort | Polsen, Erik S. |
| collection | MIT |
| description | Consistent synthesis of carbon nanotubes (CNTs) using laboratory-scale methods is essential to the development of commercial applications, particularly with respect to the verification of recipes that achieve control of CNT diameter, chirality, alignment, and density. Here, we report that transients in the moisture level and carbon concentration during the chemical vapor deposition (CVD) process for vertically aligned CNT forests can contribute significantly to run-to-run variation of height and density. Then, we show that highly consistent CNT forest growth can be achieved by physically decoupling the catalyst annealing and hydrocarbon exposure steps, to allow the gas composition to stabilize between the steps. This decoupling is achieved using a magnetically actuated transfer arm to move the substrate rapidly into and out of the CVD reactor. Compared to a reference process where the sample resides in the furnace throughout the process, the decoupled method gives 21% greater CNT forest height, reduces the run-to-run variance of height by 76%, and results in forests with improved vertical alignment (Herman's orientation parameter of 0.68 compared to 0.50). Building on this foundation, we study the influence of the moisture level during the CNT growth step and find a 30% improvement in growth rate going from the baseline condition (<15 ppm) to 40 ppm. Interestingly, however, the increased moisture concentration does not improve the catalyst lifetime or the CNT forest density, warranting further study of the role of moisture on CNT nucleation versus growth. |
| first_indexed | 2024-09-23T10:56:35Z |
| format | Article |
| id | mit-1721.1/119379 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T10:56:35Z |
| publishDate | 2018 |
| publisher | American Chemical Society (ACS) |
| record_format | dspace |
| spelling | mit-1721.1/1193792022-10-01T00:07:37Z Highly Consistent Atmospheric Pressure Synthesis of Carbon Nanotube Forests by Mitigation of Moisture Transients Polsen, Erik S. Li, Jinjing Bedewy, Mostafa White, Alvin Orbaek Tawfick, Sameh H. Hart, Anastasios John Massachusetts Institute of Technology. Department of Mechanical Engineering Massachusetts Institute of Technology. Research Laboratory of Electronics Li, Jinjing Bedewy, Mostafa White, Alvin Orbaek Tawfick, Sameh H. Hart, Anastasios John Consistent synthesis of carbon nanotubes (CNTs) using laboratory-scale methods is essential to the development of commercial applications, particularly with respect to the verification of recipes that achieve control of CNT diameter, chirality, alignment, and density. Here, we report that transients in the moisture level and carbon concentration during the chemical vapor deposition (CVD) process for vertically aligned CNT forests can contribute significantly to run-to-run variation of height and density. Then, we show that highly consistent CNT forest growth can be achieved by physically decoupling the catalyst annealing and hydrocarbon exposure steps, to allow the gas composition to stabilize between the steps. This decoupling is achieved using a magnetically actuated transfer arm to move the substrate rapidly into and out of the CVD reactor. Compared to a reference process where the sample resides in the furnace throughout the process, the decoupled method gives 21% greater CNT forest height, reduces the run-to-run variance of height by 76%, and results in forests with improved vertical alignment (Herman's orientation parameter of 0.68 compared to 0.50). Building on this foundation, we study the influence of the moisture level during the CNT growth step and find a 30% improvement in growth rate going from the baseline condition (<15 ppm) to 40 ppm. Interestingly, however, the increased moisture concentration does not improve the catalyst lifetime or the CNT forest density, warranting further study of the role of moisture on CNT nucleation versus growth. National Science Foundation (U.S.). Science and Technology Center (DMR-1120187) Pall Corporation United States. Office of Naval Research. Young Investigator Program (N000141210815) National Science Foundation (U.S.) National Institutes of Health (U.S.) (Grant No. DMR-0225180) 2018-12-03T14:00:43Z 2018-12-03T14:00:43Z 2016-05 2018-11-29T18:06:35Z Article http://purl.org/eprint/type/JournalArticle 1932-7447 1932-7455 http://hdl.handle.net/1721.1/119379 Li, Jinjing, Mostafa Bedewy, Alvin Orbaek White, Erik S. Polsen, Sameh Tawfick, and A. John Hart. “Highly Consistent Atmospheric Pressure Synthesis of Carbon Nanotube Forests by Mitigation of Moisture Transients.” The Journal of Physical Chemistry C 120, no. 20 (May 17, 2016): 11277–11287. https://orcid.org/0000-0003-4182-7533 https://orcid.org/0000-0002-7372-3512 http://dx.doi.org/10.1021/ACS.JPCC.6B02878 The Journal of Physical Chemistry C Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society (ACS) Other repository |
| spellingShingle | Polsen, Erik S. Li, Jinjing Bedewy, Mostafa White, Alvin Orbaek Tawfick, Sameh H. Hart, Anastasios John Highly Consistent Atmospheric Pressure Synthesis of Carbon Nanotube Forests by Mitigation of Moisture Transients |
| title | Highly Consistent Atmospheric Pressure Synthesis of Carbon Nanotube Forests by Mitigation of Moisture Transients |
| title_full | Highly Consistent Atmospheric Pressure Synthesis of Carbon Nanotube Forests by Mitigation of Moisture Transients |
| title_fullStr | Highly Consistent Atmospheric Pressure Synthesis of Carbon Nanotube Forests by Mitigation of Moisture Transients |
| title_full_unstemmed | Highly Consistent Atmospheric Pressure Synthesis of Carbon Nanotube Forests by Mitigation of Moisture Transients |
| title_short | Highly Consistent Atmospheric Pressure Synthesis of Carbon Nanotube Forests by Mitigation of Moisture Transients |
| title_sort | highly consistent atmospheric pressure synthesis of carbon nanotube forests by mitigation of moisture transients |
| url | http://hdl.handle.net/1721.1/119379 https://orcid.org/0000-0003-4182-7533 https://orcid.org/0000-0002-7372-3512 |
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