Lee, Cheol-Hun Lee, Jaegeun Park, Junbeom Lee, Eunyoung Kim, Seung Min Lee, Kun-Hong 2024-01-19T19:01:32Z 2024-01-19T19:01:32Z 2021-09-04 2019-11 0008-6223 https://pubs.kist.re.kr/handle/201004/119408 To increase the length and coherence of carbon nanotube (CNT) forests that are grown by chemical vapor deposition, we implant Fe ions into an Al2O3 supporting layer to weaken the gradient of Fe concentration when Fe catalyst layer is deposited on it. The weakened gradient slows loss of Fe catalyst nanoparticles (NPs) by sub-surface diffusion into the Al2O3 layer. Therefore, Fe catalyst NPs were well maintained on the Fe-implanted substrates after growth for up to 660 min, whereas significant loss of Fe NPs occurred due to sub-surface diffusion into the Al2O3 supporting layer on the non-implanted substrates. The lifetime of the catalyst was extended to 660 min (Fe-implanted substrate) from 540 min (non-implanted substrate), and the lengths of CNTs in the forest were increased to 20.3 +/- 1.0 mm (Fe-implanted substrate, maximum 21.5 mm) from 15.8 +/- 1.9 mm (non-implanted substrate). This study clearly demonstrates that sub-surface diffusion of Fe catalyst NPs into the supporting layer is the mechanism that limits CNT forest growth and may provide insights into development of methods to design an "immortal" catalyst to grow CNT forests. (C) 2019 Elsevier Ltd. All rights reserved. English PERGAMON-ELSEVIER SCIENCE LTD FIBERS EVOLUTION STRENGTH WATER FILM DIFFUSION KINETICS Rationally designed catalyst layers toward "immortal" growth of carbon nanotube forests: Fe-ion implanted substrates Article 10.1016/j.carbon.2019.06.030 1 CARBON, v.152, pp.482 - 488 CARBON 152 482 488 scie scopus 000483384900052 2-s2.0-85067418780 Chemistry, Physical Materials Science, Multidisciplinary Chemistry Materials Science Article FIBERS EVOLUTION STRENGTH WATER FILM DIFFUSION KINETICS CNT forest sub-surface diffusion ion implantation catalyst layer