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Highly Conductive Aromatic Functionalized Multi-Walled Carbon Nanotube for Inkjet Printable High Performance Supercapacitor Electrodes.

Ujjain SK, Bhatia R, Ahuja P, Attri P - PLoS ONE (2015)

Bottom Line: Carboxylic moieties (-COOH) on aromatic azide result in highly stable aqueous dispersion (max. conc. ~ 10 mg/mL H2O), making the suitable for inkjet printing.Fabricated Supercapacitors (SC) assembled using these printed substrates exhibit good electrochemical performance in organic as well as aqueous electrolytes.Capacitive retention varies from ~85-94% with columbic efficiency ~95% after 1000 charge/discharge cycles in different electrolytes, demonstrating the excellent potential of the device for futuristic power applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Indian Institute of Technology Kanpur, Kanpur, UP, India.

ABSTRACT
We report the functionalization of multiwalled carbon nanotubes (MWCNT) via the 1,3-dipolar [3+2] cycloaddition of aromatic azides, which resulted in a detangled CNT as shown by transmission electron microscopy (TEM). Carboxylic moieties (-COOH) on aromatic azide result in highly stable aqueous dispersion (max. conc. ~ 10 mg/mL H2O), making the suitable for inkjet printing. Printed patterns on polyethylene terephthalate (PET) flexible substrate exhibit low sheet resistivity ~65 Ω. cm, which is attributed to enhanced conductivity. Fabricated Supercapacitors (SC) assembled using these printed substrates exhibit good electrochemical performance in organic as well as aqueous electrolytes. High energy and power density (57.8 Wh/kg and 0.85 kW/kg) in 1M H2SO4 aqueous electrolyte demonstrate the excellent performance of the proposed supercapacitor. Capacitive retention varies from ~85-94% with columbic efficiency ~95% after 1000 charge/discharge cycles in different electrolytes, demonstrating the excellent potential of the device for futuristic power applications.

No MeSH data available.


(a) Raman spectra, (b) FTIR spectra, (c) UV-Vis spectra, and (d) Thermogravimetric curves of MWCNT and f-MWCNT.
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pone.0131475.g003: (a) Raman spectra, (b) FTIR spectra, (c) UV-Vis spectra, and (d) Thermogravimetric curves of MWCNT and f-MWCNT.

Mentions: Covalent functionalization significantly alters the Raman spectrum of pristine MWCNT and f-MWCNT, as shown in Fig 3a. Pristine MWCNTs have D and G bands, observed at 1336 cm-1 and 1561 cm-1, respectively, with an intensity ratio (ID/IG) of ~0.30. After functionalization, due to insertion reaction, a large amount of the sp2 carbon is converted to sp3, leading to an increment in the D band intensity. f-MWCNT shows increased ID/IG to 0.60 after functionalization, demonstrating the presence of the sp3 carbon network after functionalization [19]. The presence of different functionalities and the quantitative determination of aryl azide content in f-MWCNT was explored by FTIR, UV-Vis, and TGA, respectively. Fig 3b shows the FTIR spectra of pristine MWCNT and f-MWCNT. It is well known that MWCNT does not absorb a great deal of in the infrared region. In case of f-MWCNT, two important peaks were monitored: (1) the peak around the 2100 cm-1 for the azide group and (2) the peak for the carbonyl in the region of 1700–1800 cm-1. An absence of peak at 2100 cm-1 is indicative of the complete conversion of the azide into nitrene, which then attaches to the side wall of the carbon nanotubes [25]. Further, the characteristic peak observed at 1733 cm-1 is assigned to the carbonyl functional group which is present in the aryl azide unit. Peaks at 1254 and 1139 cm-1 can be assigned to C-O stretch and out of plane deformation, respectively. The strong peak observed at 1598 cm-1 is attributed to the C = C stretching of the benzene ring with C-H bending from the peak at 836 cm-1 [26,27] The UV-Vis spectrum (Fig 3c) of pristine MWCNT does not show any well defined peaks; however, background absorption is observed due to the presence of bundles of carbon nanotubes. In comparison, the UV-Vis spectrum of f-MWCNT shows an intense peak at 280 nm due to the n-π* transition in the aromatic chromophore [28]. The high intensity of the peak can be assigned to the large number of chromophores present on the carbon nanotube. The degree of functionalization on MWCNT is quantitatively determined by TGA (Fig 3d). The pristine MWCNT demonstrates an overall mass loss of ~9% at up to 800°C under N2 atmosphere, which is attributed to the organic and inorganic impurities (including organic solvents) trapped in the MWCNTs. In the case of f-MWCNTs, the first major loss between 100°C to 300°C can be attributed to the organic group attached to the side wall of the carbon nanotubes. Mass loss from 300°C to 600°C may be due to the carbonyl groups present on the aryl functional group attached to the side wall. No significant mass loss was observed after 600°C, with a total mass loss of ~54%, indicating a high level of functionalization. Consequently, f-MWCNT demonstrates high solubility in both non-polar and polar solvents. Fig 4 shows a digital photograph of the f-MWCNT dispersion in chloroform, ethanol, DMF, DMSO, and H2O before and after 1 month. The dispersions showed no change even after 1 month. f-MWCNTs form stable dispersion on mild sonication up to a maximum concentration of ~10 mg/ml in aqueous medium, which is found to be much higher than that of an existing report for functionalized CNT [20]. This dispersion was then used as ink for the inkjet printer to form f-MWCNTs film on PET and a flexible ITO substrate.


Highly Conductive Aromatic Functionalized Multi-Walled Carbon Nanotube for Inkjet Printable High Performance Supercapacitor Electrodes.

Ujjain SK, Bhatia R, Ahuja P, Attri P - PLoS ONE (2015)

(a) Raman spectra, (b) FTIR spectra, (c) UV-Vis spectra, and (d) Thermogravimetric curves of MWCNT and f-MWCNT.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4496069&req=5

pone.0131475.g003: (a) Raman spectra, (b) FTIR spectra, (c) UV-Vis spectra, and (d) Thermogravimetric curves of MWCNT and f-MWCNT.
Mentions: Covalent functionalization significantly alters the Raman spectrum of pristine MWCNT and f-MWCNT, as shown in Fig 3a. Pristine MWCNTs have D and G bands, observed at 1336 cm-1 and 1561 cm-1, respectively, with an intensity ratio (ID/IG) of ~0.30. After functionalization, due to insertion reaction, a large amount of the sp2 carbon is converted to sp3, leading to an increment in the D band intensity. f-MWCNT shows increased ID/IG to 0.60 after functionalization, demonstrating the presence of the sp3 carbon network after functionalization [19]. The presence of different functionalities and the quantitative determination of aryl azide content in f-MWCNT was explored by FTIR, UV-Vis, and TGA, respectively. Fig 3b shows the FTIR spectra of pristine MWCNT and f-MWCNT. It is well known that MWCNT does not absorb a great deal of in the infrared region. In case of f-MWCNT, two important peaks were monitored: (1) the peak around the 2100 cm-1 for the azide group and (2) the peak for the carbonyl in the region of 1700–1800 cm-1. An absence of peak at 2100 cm-1 is indicative of the complete conversion of the azide into nitrene, which then attaches to the side wall of the carbon nanotubes [25]. Further, the characteristic peak observed at 1733 cm-1 is assigned to the carbonyl functional group which is present in the aryl azide unit. Peaks at 1254 and 1139 cm-1 can be assigned to C-O stretch and out of plane deformation, respectively. The strong peak observed at 1598 cm-1 is attributed to the C = C stretching of the benzene ring with C-H bending from the peak at 836 cm-1 [26,27] The UV-Vis spectrum (Fig 3c) of pristine MWCNT does not show any well defined peaks; however, background absorption is observed due to the presence of bundles of carbon nanotubes. In comparison, the UV-Vis spectrum of f-MWCNT shows an intense peak at 280 nm due to the n-π* transition in the aromatic chromophore [28]. The high intensity of the peak can be assigned to the large number of chromophores present on the carbon nanotube. The degree of functionalization on MWCNT is quantitatively determined by TGA (Fig 3d). The pristine MWCNT demonstrates an overall mass loss of ~9% at up to 800°C under N2 atmosphere, which is attributed to the organic and inorganic impurities (including organic solvents) trapped in the MWCNTs. In the case of f-MWCNTs, the first major loss between 100°C to 300°C can be attributed to the organic group attached to the side wall of the carbon nanotubes. Mass loss from 300°C to 600°C may be due to the carbonyl groups present on the aryl functional group attached to the side wall. No significant mass loss was observed after 600°C, with a total mass loss of ~54%, indicating a high level of functionalization. Consequently, f-MWCNT demonstrates high solubility in both non-polar and polar solvents. Fig 4 shows a digital photograph of the f-MWCNT dispersion in chloroform, ethanol, DMF, DMSO, and H2O before and after 1 month. The dispersions showed no change even after 1 month. f-MWCNTs form stable dispersion on mild sonication up to a maximum concentration of ~10 mg/ml in aqueous medium, which is found to be much higher than that of an existing report for functionalized CNT [20]. This dispersion was then used as ink for the inkjet printer to form f-MWCNTs film on PET and a flexible ITO substrate.

Bottom Line: Carboxylic moieties (-COOH) on aromatic azide result in highly stable aqueous dispersion (max. conc. ~ 10 mg/mL H2O), making the suitable for inkjet printing.Fabricated Supercapacitors (SC) assembled using these printed substrates exhibit good electrochemical performance in organic as well as aqueous electrolytes.Capacitive retention varies from ~85-94% with columbic efficiency ~95% after 1000 charge/discharge cycles in different electrolytes, demonstrating the excellent potential of the device for futuristic power applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Indian Institute of Technology Kanpur, Kanpur, UP, India.

ABSTRACT
We report the functionalization of multiwalled carbon nanotubes (MWCNT) via the 1,3-dipolar [3+2] cycloaddition of aromatic azides, which resulted in a detangled CNT as shown by transmission electron microscopy (TEM). Carboxylic moieties (-COOH) on aromatic azide result in highly stable aqueous dispersion (max. conc. ~ 10 mg/mL H2O), making the suitable for inkjet printing. Printed patterns on polyethylene terephthalate (PET) flexible substrate exhibit low sheet resistivity ~65 Ω. cm, which is attributed to enhanced conductivity. Fabricated Supercapacitors (SC) assembled using these printed substrates exhibit good electrochemical performance in organic as well as aqueous electrolytes. High energy and power density (57.8 Wh/kg and 0.85 kW/kg) in 1M H2SO4 aqueous electrolyte demonstrate the excellent performance of the proposed supercapacitor. Capacitive retention varies from ~85-94% with columbic efficiency ~95% after 1000 charge/discharge cycles in different electrolytes, demonstrating the excellent potential of the device for futuristic power applications.

No MeSH data available.