what a rule surfactants play in synthesis cnts array
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What a rule surfactants play in synthesis CNTs array. Shuchen Zhang, Yanhe Zhang 2013-05-27. Outline. Background. Problem. Surfactants and CNTs. Conclusion. Acknowledgement. Background. - PowerPoint PPT PresentationTRANSCRIPT
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What a rule surfactants play in synthesis CNTs array
Shuchen Zhang, Yanhe Zhang
2013-05-27
Shuchen Zhang, Yanhe Zhang
2013-05-27
Background
Problem
Surfactants and CNTs
Conclusion
Outline
Acknowledgement
Background
Fig.1 Schematic of the process from graphene to CNTs Fig.1 Schematic of the process from graphene to CNTs
Single-walled carbon nanotubes (SWNTs) have been regarded as one of the best candidates for future application in next generation integrated circuits due to their unique structures and superb properties:1)High strength;2)Excellent electrical properties ;3)Absorbtion band (infrared wavelengths ).
Single-walled carbon nanotubes (SWNTs) have been regarded as one of the best candidates for future application in next generation integrated circuits due to their unique structures and superb properties:1)High strength;2)Excellent electrical properties ;3)Absorbtion band (infrared wavelengths ).
Background
Fig.2 Schematic of CNTs Fig.2 Schematic of CNTs
Fig.3 Schematic of zigzag, armchair, and chiral CNTs
Fig.3 Schematic of zigzag, armchair, and chiral CNTs
2 2C Cad n nm m
1tan 3 / (2 )m n m
1 2n mhC a a
2n+m=3q 2n+m=3q
Background
Fig.5 Band structure of grapheneFig.5 Band structure of graphene
Fig.4 States density of different CNTs Fig.4 States density of different CNTs
1 ） the band structure of graphene is relatively simple；
2 ） but for CNT, its band structure is relatively complicated, related to diameter and chiral, etc.
1 ） the band structure of graphene is relatively simple；
2 ） but for CNT, its band structure is relatively complicated, related to diameter and chiral, etc.
Problem
Fig.6 Band structure of grapheneFig.6 Band structure of graphene
2n+m=3q 2n+m=3q
××
Surfactant and CNTs
Selective Band Structure Modulation of Single-Walled Carbon Nanotubes in Ionic Liquids
Selective Band Structure Modulation of Single-Walled Carbon Nanotubes in Ionic Liquids
Jinyong Wang, and Yan Li, J. Am. Chem. Soc., 2009Jinyong Wang, and Yan Li, J. Am. Chem. Soc., 2009
1) PFOA, SDS, LDS, PPFOS, PDS
2) They can be classified two kinds:
① PFOA, SDS, LDS；
②PPFOS, PDS.
1) PFOA, SDS, LDS, PPFOS, PDS
2) They can be classified two kinds:
① PFOA, SDS, LDS；
②PPFOS, PDS.
Fig.7 Absorbance spectrum of CNTs with different surfactants
Fig.7 Absorbance spectrum of CNTs with different surfactants
Surfactant and CNTs
Type :Ⅰ E22 transitions ( 1100 ∼nm) of S-nanotubes( 1.5-1.7 ∼nm) and E11transitions ( 750 ∼nm) of M-nanotubes( 1.5 ∼nm).
Type :Ⅱ E33 transitions( 550-∼650 nm) of S-nanotubes( 1.5-∼1.7 nm).
Type :Ⅲ E33 electronic transitions ( 400-500 nm) of ∼S-nanotubes( 1.2-1.4 nm)∼
Type :Ⅰ E22 transitions ( 1100 ∼nm) of S-nanotubes( 1.5-1.7 ∼nm) and E11transitions ( 750 ∼nm) of M-nanotubes( 1.5 ∼nm).
Type :Ⅱ E33 transitions( 550-∼650 nm) of S-nanotubes( 1.5-∼1.7 nm).
Type :Ⅲ E33 electronic transitions ( 400-500 nm) of ∼S-nanotubes( 1.2-1.4 nm)∼
Fig.8 Absorbance spectra and Raman spectraFig.8 Absorbance spectra and Raman spectra
Jinyong Wang, and Yan Li, J. Am. Chem. Soc., 2009Jinyong Wang, and Yan Li, J. Am. Chem. Soc., 2009
Surfactant and CNTs
Fig.9 Band structure of S- and M-CNTsFig.9 Band structure of S- and M-CNTs
Due to the modification, electrons should transfer from the SWCNTs to the surfactants, thus resulted in the positive charging of SWCNTs. It can be clearly seen that shift of the Fermi energy and the band structure occur as a result of charge transfer.
Due to the modification, electrons should transfer from the SWCNTs to the surfactants, thus resulted in the positive charging of SWCNTs. It can be clearly seen that shift of the Fermi energy and the band structure occur as a result of charge transfer.
Jinyong Wang, and Yan Li, J. Am. Chem. Soc., 2009Jinyong Wang, and Yan Li, J. Am. Chem. Soc., 2009
Surfactant and CNTs
Fig.10 Possible interaction mechanismFig.10 Possible interaction mechanism
The possible interaction mechanism:
Because of the large positive charge density of the cations, the high-energy electrons of the SWCNTs near the Fermi level transfer to the lowest unoccupied orbitals of the cations. A stable “cation-π” complex is formed at the nanotube surface.
The possible interaction mechanism:
Because of the large positive charge density of the cations, the high-energy electrons of the SWCNTs near the Fermi level transfer to the lowest unoccupied orbitals of the cations. A stable “cation-π” complex is formed at the nanotube surface.
Jinyong Wang, and Yan Li, J. Am. Chem. Soc., 2009Jinyong Wang, and Yan Li, J. Am. Chem. Soc., 2009
Surfactant and CNTs
Sorting out Semiconducting Single-Walled CarbonNanotube Arrays by Washing off Metallic Tubes Using
SDS Aqueous Solution
Sorting out Semiconducting Single-Walled CarbonNanotube Arrays by Washing off Metallic Tubes Using
SDS Aqueous Solution
Yue Hu , Yabin Chen , Pan Li , a nd Jin Zhang *, Small., 2013Yue Hu , Yabin Chen , Pan Li , a nd Jin Zhang *, Small., 2013
Fig.11 Schematic illustration of sorting out s- SWNT arraysFig.11 Schematic illustration of sorting out s- SWNT arrays
Surfactant and CNTs
Yue Hu , Yabin Chen , Pan Li , a nd Jin Zhang *, Small., 2013Yue Hu , Yabin Chen , Pan Li , a nd Jin Zhang *, Small., 2013
Fig.12 SEM and AFM of CNTs before sortingFig.12 SEM and AFM of CNTs before sorting Fig.13 Compare the AFM and Raman before and after sorting
Fig.13 Compare the AFM and Raman before and after sorting
Surfactant and CNTs
Yue Hu , Yabin Chen , Pan Li , a nd Jin Zhang *, Small., 2013Yue Hu , Yabin Chen , Pan Li , a nd Jin Zhang *, Small., 2013
Fig.14 SEM and AFM to character the variation of CNTsFig.14 SEM and AFM to character the variation of CNTs
Statistical result indicates that the SWNTs with bigger average diameter changes are mostly disappeared after separation while SWNTs with smaller average diameter changes.
Statistical result indicates that the SWNTs with bigger average diameter changes are mostly disappeared after separation while SWNTs with smaller average diameter changes.
Surfactant and CNTs
Yue Hu , Yabin Chen , Pan Li , a nd Jin Zhang *, Small., 2013Yue Hu , Yabin Chen , Pan Li , a nd Jin Zhang *, Small., 2013
Fig.15 SEM for separation and the FET of CNTs after sortingFig.15 SEM for separation and the FET of CNTs after sorting
Conclusion
In order to get a perfect array only made by s-CNTs, we have made great effort to sorting out the s-CNTs from to the CNTs mixture by their difference, especially the density of state. However, these methods still retain some problems:
1) Sorting out the s-CNTs in the solution will bring about a great question, making an array is difficult;
2) Sorting out the s-CNTs on the substrate will lead to a low product of s-CNTs to hard to be an array;
3) A good method to separate the s-CNTs with the m-CNTs also lead to defect on the CNTs and hard to get a pure CNTs.
In order to get a perfect array only made by s-CNTs, we have made great effort to sorting out the s-CNTs from to the CNTs mixture by their difference, especially the density of state. However, these methods still retain some problems:
1) Sorting out the s-CNTs in the solution will bring about a great question, making an array is difficult;
2) Sorting out the s-CNTs on the substrate will lead to a low product of s-CNTs to hard to be an array;
3) A good method to separate the s-CNTs with the m-CNTs also lead to defect on the CNTs and hard to get a pure CNTs.
Acknowledgements
Pro. YanAll the audiences
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