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In a recently published paper in Science Advances, Feng Ding of the Center for Multidimensional Carbon Materials, within the Institute of Basic Science (IBS, South Korea) and colleagues, have achieved the creation of a specific type of carbon nanotubes (CNTs) with a selectivity of 90%, and expanded the current theory that explains the synthesis of these promising nano-cylinders. CNTs are incredibly strong and light nanomaterials made of carbon with superior current carrying capacity and very high thermal conductivity, making them ideal for electronic applications. Although CNTs are considered as some of the most interesting materials for the future, scientists are still struggling for their controllable synthesis.

Interestingly, the new theory of CNT growth leads to a new mechanism to selectively grow a specific type of CNTs, denoted as (2n, n) CNTs, which is characterized by the maximum number of active sites at the interface between the CNT and the catalyst. This CNT structure would correspond to rolling a sheet of graphite diagonally at an angle of around 19 degrees.

"If there is no carbon etching and the carbon nanotubes growth is slow, carbon atoms on the catalyst surface will accumulate," says Jin Zhang, co-author of the study and professor of Peking University, China. "This may lead to the formation of graphitic or amorphous carbon, which are established mechanisms of carbon nanotube growth termination. In this case, only carbon nanotubes which are able to add carbon atoms on their walls, that is with the highest number of active sites, can survive."

Guided by the new theoretical understanding, the researchers were able to design experiments that produced (2n, n) CNTs with a selectivity of up to 90%: the highest selective growth of this type of CNT was achieved in the absence of any etching agent and with a high feedstock concentration.

Source: https://www.ibs.re.kr/cop/bbs/BBSMSTR_000000000738/selectBoardArticle.do

Maoshuai He, Xiao Wang, Shuchen Zhang, Hua Jiang, Filippo Cavalca, Hongzhi Cui, Jakob B. Wagner, Thomas W. Hansen, Esko Kauppinen, Jin Zhang, Feng Ding. Growth kinetics of single-walled carbon nanotubes with a (2n, n) chirality selection. Science Advances, 2019; 5 (12): eaav9668 DOI: 10.1126/sciadv.aav9668

Original Submission