multifunctional water soluble carbon nano onions from...
TRANSCRIPT
9-June-20171
Multifunctional Water Soluble Carbon NanoOnions from Flaxseed Oil for Visible Light Induced
Photocatalytic Applications and Label FreeDetection of Al(III) Ions
Trends in Nanotechnology
Dr. Kumud Malika Tripathi (Ph.D)Assistant Professor
Prof. TaeYoung Kim GroupGachon Bionano Research InstituteDepartment of BionanotechnologyGachon University, South Korea
What are Carbon Nano Onions
In the electron microscope we only see the shell contours
Multilayer giant fullerenes, which consist of multiple concentric graphitic shells to form encapsulated structures
Japanese Scientist, S. Iijima (1980) D. Ugarte (1992) Coined the word “Carbon Onions”
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Cost Effective Synthesis of Carbon Nano Onions Generally used sophisticated synthetic procedures are expensive, time
consuming and often lead to the formation of metaldeposited/contaminated nano-carbons.
Our approach here is very simple, green and utilizes cost effectivetechnique of wick pyrolysis.
High yield synthesis with ease in reproducibility.
Further oxidation with nitric acid leads to the formation of water solubleversion of carbon nano onions and impart fluorescent.
Amenable to surface modification/functionalization.
Aqueous solubility makes these nano-carbons a potential candidate toexplore their potentials in both environment and biomedical applications.
Wick
Pyrolysis
[O]
HNO3
CO OH
OHO
O
O O
CO
HO
CO
HO
COHO
CO
OH
C
O
OH
HO
OH
Flaxseed oil Carbon Nano OnionsWater soluble
Carbon Nano Onions
Wick Pyrolysis of
Flaxseed Oil & soot was collected
Refluxed in Conc. HNO3 for
10 h
Purified by washing with
water viacentrifugation
Filter with 0.45, 0.2 & 0.1 µ membrane
Yield 85 %
RepeatedEvaporation on water bath till
pH = 7
Fabrication of Carbon Nano Onions
ACS Sustainable Chem. Eng., 2017, 5 , 3982–3992. 4
Microscopic Characterization
10 nm
(b)
10 nm
(a)
5 nm
(c)
5
Spectroscopic Characterization
500 1000 1500 2000 2500 3000 3500
Inte
nsity
(a.u
.)
Wavenumber (cm-1)
15861341
15911335 wsCNOs As-synthesized CNOs
4000 3500 3000 2500 2000 1500 1000 500
3017
123615951720
5501222
1607
3430 As-synthesized CNOs wsCNOs
Tran
smitt
ance
[%]
Wavenumber cm-1
3430
100 200 300 400 500 600 700 800 90050
60
70
80
90
100
Weig
ht (%
)
Temperature (oC)
As-synthesized CNOs wsCNOs
(a) (b)
(c) (d)
10 20 30 40 50 60 70 80
Inte
nsity
(a.u
.)
Angle (2θ)
44
44
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wsCNOs As-synthesized CNOs
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(a) FTIR (b) Raman (c) TGA and (d) XRD spectra of CNOs (black line) & wsCNOs (blueline) 6
Optical Characterization
200 300 400 500 600 700 800 900
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Abso
rban
c e
Wavelength (nm)
246
510 520 530 540 550 560 570 580
Inten
sity
Wavelength (nm)
380 390 400
300 310 320 330 340 350 360
Inten
sity
Wavelength (nm)
335
(a) (b)
(c) (d)
(1) (2)
(a) UV-Vis absorption spectrum and digital image of an aqueous solution of wsCNOs under daylight, (2) under 385 nm λex; (b) PL emission spectra at different wavelengths; (c) PL excitation spectrum at a 523 nm emission wavelength; (d) Fluorescence image of wsCNOs at 488 nm band pass filter, scale bar 20 µm. 7
Utility of Water Soluble Carbon Nano Onions
In highly selective sensing of trace amount of Al(III) in homogenous aqueous medium with low detection limit.
Photocatalytic degradation of toxic organic dyes for water remediation
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Application in photocatalytic dye degradation
(a)(1) (2)
AfterBefore
Green fluorescentwsCNOs /hν
Visible light
UV-Vis absorbance spectra of methylene blue at set 10 minutes of time intervals with (a)wsCNOs and (b) CNOs. Extent of (c) MB photodegradation at different visible lightirradiation time with CNOs and wsCNOs; (d) Plot of ln(C/Co) for MB photodegradationwith CNOs and wsCNOs .
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LUMO
HOMO
O2.
O2
Visible light
wsCNOs
h+ h+ h+ h+
e- e- e- e-
H2O
HO.
MBMB
MB .O2
Degradation
ACS Sustainable Chem. Eng., 2017, 5 , 3982–3992.
Visible Light Induced Dye Degradation
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CO OH
OHO
O
O O
CO
HO
CO
HO
COHO
CO
OH
C
O
OH
HO
OH
CO OH
OHO
O
O O
CO
O
CO
O
COHO
CO
O
C
O
O
O
O
Al(III)Al(III)
Al(III)
Al(III)
Al(III)
Al(III)
Al(III)
Al(III)
Green fluorescentwsCNOs Fluorescence “Turn-off”
Excitation 390 nm
Emission 531 nm
Al(III)
Fluorescence Quenched
Application in Al(III) Sensing
ACS Sustainable Chem. Eng., 2017, 5 , 3982–3992. 11
510 520 530 540 550 560 570
Inte
nsity
(a.u
.)
Wavelength (nm)
wsCNOs 10 µL 20 µL 30 µL 40 µL 50 µL 60 µL 70 µL 80 µL 90 µL 100µL
wsCNOs Cl- I-NO3-
SO4--
CH3COO-0.0
0.2
0.4
0.6
0.8
1.0
Rel
ativ
e flu
ores
cenc
e in
tens
ity
wsCNOsNa+ K+
Mg2+Ca2+Ba2+Cr2+Cr3+Cr6+Fe2+Fe3+Cu+Cu2+Al3+Ag+
Cd2+Co2+Hg+
Hg2+Mn2+Ni2+Pb2+Zn2+
0.80
0.85
0.90
0.95
1.00
Relat
ive flu
oresc
ence
inten
sity
510 520 530 540 550 560 570
Inte
nsity
(a.u
.)
Wavelength (nm)
wsCNOs 10 µL 20 µL 30 µL 40 µL 50 µL 60 µL 70 µL 80 µL 90 µL 100µL
(a) (b) (c)
(d) (e)
0 5 10 15 20 25 30 351.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
Concentration of Al(III) (µm)I o
/I
Application in Al(III) Sensing
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Conclusion Facile synthetic route for the synthesis of homogenous wsCNOs by traditional
pyrolysis of flaxseed oil as the carbon precursor.
Further oxidation with HNO3 leads to the formation of water soluble version ofCNOs via functionalization with –COOH (surface defects) and further impartfluorescent.
wsCNOs were characterized by TEM, HRTEM, FTIR, Raman, TGA, XRD and zetapotential studies .
Interestingly synthesized CNOs displayed multifunctional applications in sensingand photocatalysis.
wsCNOs used as a fluorescent probe for the sensitive detection of Al(III) ions basedupon florescence “turn-off” technique with a 0.77 µm detection limit.
wsCNOs exhibited excellent visible light driven photocatalytic performancetowards degradation of organic dyes.
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