Extinction Coefficients and Purity

of Single-walled Carbon Nanotubes

Bin Zhao

Haddon Research Group

Departments of Chemistry and

Chemical & Environmental Engineering

Center for Nanoscale Science and Engineering

University of California, Riverside

Applications of Carbon nanotubes

the needs of high purity

High strength light weight composites

AFM probes

Nano-electronic

devices

Field emission devices

Hydrogen storage

fuel cells

biology

carbon

nanotubes

Purity evaluation by using

electron microscopy (SEM)

Give non-quantitative

evaluation of the

purity of SWNTs.

Detect samples at 10-12 gram

scale.

a

c

b

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

Absorb

ance

(eV)

AA(S)

AA(I)

AA(N)

M11

S22

S11

Energy of Interband transition of SWNTs

-1

0

1

-1

0

1

Semiconducting

SWNTs

metallic

SWNTs

S22

S11

M11

DOS (a.u.)

DOS (a.u.)

ene

rgy (

eV

)e

ne

rgy (

eV

)

8000 10000 12000 14000 16000 180000.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

c

b

a

Abso

rban

ce

Wavenumber (cm-1)

Solution phase near-IR spectra of SWNT samples

Purity Evaluation of As-Prepared Single-Walled

Carbon Nanotube Soot by Use of Solution-Phase

Near-IR Spectroscopy

M. E. Itkis, D. E. Perea, S. Niyogi, S. M. Rickard, M. A. Hamon, H.Hu,

B. Zhao, and R. C. Haddon* Nano lett. 2003, 3, 309.

reference sample (R)

8000 10000 120000.0

0.2

0.4

REFERENCE (R)

AA(T,R)

Ab

so

rba

nce

Wavenumber (cm-1)

0.0

0.1

AA(S,R)

R

8000 10000 12000

AA(T,X)

SWNTs: 67%

CARBONACEOUS

IMPURITIES: 33%

XAA(S,X)

AA(S, R)

AA(T, R)= 0.141

AA(S, X)

AA(T, X)= 0.095

Purity of X against R = (0.095/0.141)*100% =67%

5000 10000 150000.00

0.02

0.04

0.06

0.08

0.10

0.12

Wavenumber (cm-1)

5000 10000 150000.00

0.02

0.04

0.06

0.08

0.10

0.12

M11

S22

S11

Absorb

ance

Wavenumber (cm-1)

Controlled Purification of Single-Walled Carbon

Nanotube Films by Use of Selective Oxidation and

Near-IR Spectroscopy

O2-292oC-4h

R. Sen, S. M. Rickard, M. E. Itkis, and R. C. Haddon*

Chem. Mater. 2003, 15, 4273.

AP-SWNT Oxidized SWNT

8000 9000 10000 110000.000

0.004

0.008

AA(S)=17.7

Absorb

ance

Wavenumber (cm-1)

0.00

0.02

0.04

0.06

0.08

AA(T)=278

0.00

0.02

0.04

0.06

0.08

AA(T)=67

8000 9000 10000 110000.000

0.004

0.008

AA(S) =12.8

Ab

so

rba

nce

Wavenumber (cm-1)

AA(S)/AA(T) = 0.0635 AA(S)/AA(T) = 0.191

Relative Purity (RP) = = 3.0AA(S, OX)/AA(T, OX)

AA(S, AP)/AA(T, AP)

AP-SWNT Oxidized SWNT

100

80

60

40

20

0

20

40

60

80

16M/12h16M/6h

7M/12h7M/6h3M/48h

3M/24h3M/12h

AP

Weig

ht lo

ss%

Weig

ht%

SWNT weight%

Metal weight%

Carbonaceous impurities weight%

Lost Weight%

AP-SWNT

7M/6h

15M/12hH. Hu, B. Zhao, M. E. Itkis and R. C. Haddon

J. Phys. Chem. B. 2003, 107, 13838.

Nitric Acid Purification of

Single-Walled Carbon Nanotubes

Extinction coefficient study of single-walled carbon

nanotubes and other carbonaceous materials

Solution phase NIR is a powerful tool to assess

carbonaceous purity of SWNTs.

Demonstration of the applicability of Beer’s law of

carbonaceous materials.

Effective extinction coefficient study of SWNTs and

carbonaceous materials – a way to estimate the universal

purity of SWNTs.

B. Zhou, et. al.

JPCB 2003, 107, 13588.

Absorptivity of Functionalized

Single-Walled Carbon Nanotubes

in Solution

J. A. Bahr, et. al.

Chem. Comm. 2001, 193.

Dissolution of small diameter

single-wall carbon nanotubes

in organic solvents

10000 15000 20000 250000.0

0.2

0.4

0.6

0.8

1.0

carbon black

Absorb

ance

10000 15000 20000 25000

Wavenumber (cm-1)

MWNT

10000 15000 20000 25000 30000

AP-SWNT (EA)

10000 15000 20000 250000.0

0.2

0.4

0.6

0.8

1.0

Absorb

ance purified SWNT (EA)

10000 15000 20000 25000

AP-SWNT (LO)

10000 15000 20000 25000 30000

AP-SWNT (HC)

The NIR spectra of carbonaceous materials

1 2 3

S11

M11

M11

S22

S22

S11

M11

S22

S11

HC

LO

EA

A

bsro

ba

nce

(a

.u.)

Energy (eV)

Electronic structures of SWNTs

produced by different methods

Purity of EA prepared SWNTs (against R-SWNT)

63

37

70

11

3932

116

133

113

0

20

40

60

80

100

120

140

Purity

(%

)

AP

1-E

AA

P2-E

A

AP

3-E

A

AP

4-E

A

AP

5-E

A

AP

6-E

A

P1-E

A

P2-E

A

P3-E

A

Sample AA(S) AA(T) Purity

(% of R-SWNT)

AP1-EA 101.9 1149.5 63

AP2-EA 50.2 962.2 37

AP3-EA 113.9 1162 70

AP4-EA 13.7 892.1 11

AP5-EA 60.4 1109.8 39

AP6-EA 43.2 960.1 32

P1-EA 158.5 971.6 116

P2-EA 252.3 1348.1 133

P3-EA 208.8 1304 113

(a) (b)

P1-EA P2-EA

The purity of LO SWNTs

Method 1:

AA(S, LO)

AA(S, LO) + AA(B, LO)= 0.066

AA(S, R)

AA(S, R) + AA(B, R)= 0.141

Purity of LO-SWNT = (0.066/0.141) 100% = 47%

0.00

0.05

0.10

0.15

0.20

Wavenumber (cm-1)

AA(B, R)

AA(S, R)

Absorb

ance

8000 9000 10000 11000 12000 130000.00

0.05

0.10

0.15

AA(B, LO)

AA(S, LO)

AA(S, LO)

AA(S, LO) + AA(B, LO)= 0.046

AA(S, R)

AA(S, R) + AA(B, R)= 0.096

Purity of LO-SWNT = (0.046/0.096) 100% = 48%

Method 2:

0.00

0.05

0.10

0.15

0.20

Wavenumber (cm-1)

AA(B, R)

AA(S, R)

Ab

so

rba

nce

8000 9000 10000 11000 12000 130000.00

0.05

0.10

0.15

AA(B, LO)

AA(S, LO)

Purity of carbonaceous materials (against R-SWNT)

Purity

(% of R-SWNT)

AP1-EA 101.9 1149.5 63

AP2-EA 50.2 962.2 37

AP3-EA 113.9 1162 70

AP4-EA 13.7 892.1 11

AP5-EA 60.4 1109.8 39

AP6-EA 43.2 960.1 32

P1-EA 158.5 971.6 116

P2-EA 252.3 1348.1 133

P3-EA 208.8 1304 113

AC 1 831.4 < 1

HC 138.5 2127.4 49~69

P-HC 165.2 2078.7 55~76

LO 62.6 1252.2 48~48

P-LO 85.4 803.8 92~110

Sample AA(S) AA(T)

63

37

70

11

3932

116

133

113

1

5966

47

101

0

20

40

60

80

100

120

140

Purity

(%

)

AP

1-E

AA

P2-E

A

AP

3-E

A

AP

4-E

A

AP

5-E

A

AP

6-E

A

P1-E

A

P2-E

A

P3-E

A

AC

HC

P

-HC

LO

P

-LO

8000 10000 12000 14000 16000

0.10

0.15

0.20

0.25

0.30

0.35

M11

S22

Absorb

ance

wavenumber (cm-1)

8000 10000 12000 14000 16000

0.10

0.15

0.20

0.25

0.30

0.35

AA(I)

AA(N)

AA(S)

M11

S22

Absorb

ance

wavenumber (cm-1)

AA(T)=AA(S) + AA(N) + AA(I)

AA(T)

A(T) = A(S) + A(N) + A(I)

C(T) = C(NS) + C(I)

A(I) = (I) C(I) l

A(N) = (N) C(NS) l

A(S) = (S) C(NS) l

effective spectral absorbance: A =spectral width of cutoff

AA

The applicability of Beer’s law of carbonaceous materials

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

0

10

20

30

40

50

AP1-EA

AP2-EA

AP4-EA

P1-EA

P2-EA

Absorb

ance/C

oncentr

ation

Concentration (mg/mL)

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.140

10

20

30

40

50

AP1-EA

AP2-EA

AP4-EA

P1-EA

P2-EA

AC

CB

MWNT

Absorb

ance/C

oncentr

ation

Concentration (mg/mL)

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

0

10

20

30

40

50

AP1-EA

AP2-EA

AP4-EA

P1-EA

P2-EA

AC

CB

MWNT

HC(S11

)

HC(S22

)

P-HC(S11

)

P-HC(S22

)

Absorb

ance/C

oncentr

ation

Concentration (mg/mL)

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

0

10

20

30

40

50

AP1-EA

AP2-EA

AP4-EA

P1-EA

P2-EA

AC

CB

MWNT

HC(S11

)

HC(S22

)

P-HC(S11

)

P-HC(S22

)

LO

P-LO

AP-C60

P-C60

Absorb

ance/C

oncentr

ation

Concentration (mg/mL)

(S) (T)

(Lmol-1cm-1) (Lmol-1cm-1)

AP1-EA 31 345

AP2-EA 15 289

AP3-EA 34 349

AP4-EA 4 268

AP5-EA 18 333

AP6-EA 13 288

P1-EA 48 292

P2-EA 76 405

P3-EA 63 391

AC 0 261

CB - 437

MWNT - 364

HC (S11) 118 382

HC (S22) 32 496

P-HC (S11) 129 386

P-HC (S22) 39 487

LO 15 301

P-LO 20 194

AP-C60 - 143

P-C60 - 2

Sample

Beer’s Law: A = C l

C = 0.01mg/mL 8.3 10-4 mol/LAP

1-E

A

AP

2-E

A

AP

3-E

A

AP

4-E

A

AP

5-E

A

AP

6-E

A

P1-E

A

P2-E

A

P3-E

A

AC

CB

MW

NT

HC

(S11)

HC

(S22)

P-H

C (S11)

P-H

C (S22)

LO

P-L

O

AP

-C60

P-C

60

345

289

349

268

333

288 292

405

391

261

437

364382

496

386

487

301

194

143

2

31

15 344 18 13

4876

63

0.1

118

32

129

39

15 20

0

50

100

150

200

250

300

350

400

450

500

(S)

(T)

A(T) = (I) C(I) + [(N) + (S)] C(NS)

A(T) = (I) C(T) + [(N) + (S) – (I)] (S) -1 A(S)

A(T)=A(S) + A(N) + A(I)

C(T)=C(NS) + C(I)

the intercept is (I) C(T)

the gradient is [(N) + (S) – (I)] (S) -1.

A(I) = (I) C(I)

A(N) = (N) C(NS)

A(S) = (S) C(NS)

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

0.22

0.24

0.26

0.28

0.30

0.32

0.34

A(T

)

A(S)

C = 0.01mg/mL 8.3 10-4 mol/L

(I) = 270 10 L mol-1 cm-1

the gradient is [(N) + (S) – (I)] (S) -1 2

(N) (S) + (I) = (S) + 270 L mol-1 cm-1

Conclusion

Solution phase NIR is a powerful tool to assess

carbonaceous purity of SWNTs.

The Effective extinction coefficient of EA produced

SWNTs falls in the range of 268 ~ 391 L mol-1 cm-1 .

The effective extinction coefficient of carbonaceous

impurities in SWNTs is 270 10 L mol-1 cm-1 (calculation).

The relationship of extinction coefficient of carbonaceous

contents in EA-SWNTs is:

(N) (S) + (I) = (S) + 270 L mol-1 cm-1

Acknowledgement

Haddon research group

Dr. Robert C. Haddon (advisor)

Dr. Mikhail E. Itkis

Hui Hu

Dr. Rahul Sen

Daniel Perea

Sandip Niyogi

Dr. Elena Bekyarova

James Love

Jingtao Zhang

Shawna M. Rickard