electronic supplementary information1 electronic supplementary information co(ii)-porphyrins...
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Electronic Supplementary information
Co(II)-porphyrins decorated carbon nanotubes as catalysts for oxygen
reduction reactions: An approach for fuel cell improvement†
Piyush Kumar Sonkar1, Kamal Prakash
2, Mamta Yadav
1, Vellaichamy Ganesan*
1, Muniappan
Sankar2, Rupali Gupta
1, Dharmendra Kumar Yadav
1
1Department of Chemistry, Institute of Science
Banaras Hindu University, Varanasi-221 005, UP, India
Telephone: + 91-542-6701609; Fax: + 91-542-2368127
Email: [email protected] and [email protected]
2Department of Chemistry, Indian Institute of Technology Roorkee,
Roorkee-247667, Uttarakhand, India
* Corresponding author
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2017
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Section S1
Conversion of observed experimental potential to reversible hydrogen electrode, RHE scale
The experimentally observed potentials against Ag/AgCl or saturated calomel electrode, SCE are
converted to the reversible hydrogen electrode (RHE) scale according to the Nernst equation
[SR1-SR3]:
ERHE = EAg/AgCl + 0.059pH + E0Ag/AgCl (1)
ERHE = ESHE + 0.059pH + E0
SHE (2)
where EAg/AgCl is the experimentally measured potential against Ag/AgCl reference electrode and
E0
Ag/AgCl is 0.199 V at 25 ºC. Similarly, ESCE is the experimentally measured potential against
SCE reference and E0
SCE is 0.241 at 25 ºC.
References
[SR1] G. Ferrero, K. Preuss, A. Fuertes, M. Sevilla and M.-M. Titirici, Journal of Materials
Chemistry A, 2016, 4, 2581-2589.
[SR2] A. J. Bard, L. R. Faulkner, J. Leddy and C. G. Zoski, Electrochemical methods:
fundamentals and applications, Wiley New York, 1980.
[SR3] D. Y. Chung, S. W. Jun, G. Yoon, S. G. Kwon, D. Y. Shin, P. Seo, J. M. Yoo, H. Shin,
Y.-H. Chung and H. Kim, Journal of the American Chemical Society, 2015, 137, 15478-
15485.
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Table S1 Composition of MWCNT-CoTHPP, MWCNT-CoTCPP and MWCNT-CoTPP in
different weight ratios and amount of metal complex adsorbed.
Name of the
sample
(MWCNT (in mg)
: metal complex
(in mmoles))
Initial composition added Final composition after adsorption
MWCNT
(mg)
Cobalt
porphyrin
(mg)
% N
(obtained
from
elemental
analysis)
N
calculated
(mg)
Cobalt
porphyrin
calculated
(mg)
MWCNT-CoTHPP
(10:0.02)
10 14.70 1.11 0.266 2.94
MWCNT-CoTPP
(10:0.02)
10 13.42 4.10 1.428 10.065
MWCNT-CoTCPP
(10:0.02)
10 16.94 2.12 0.574 8.47
MWCNT-CoTHPP
(10:0.01)
10 07.35 1.07 0.184 2.205
MWCNT-CoTPP
(10:0.01)
10 06.71 4.14 1.442 6.70
MWCNT-CoTCPP
(10:0.01)
10 08.47 2.03 0.378 5.929
MWCNT-CoTHPP
(10:0.005)
10 03.68 0.65 0.088 1.1025
MWCNT-CoTPP
(10:0.005)
10 03.35 1.19 0.1596 1.878
MWCNT-CoTCPP
(10:0.005)
10 04.24 0.77 0.1092 1.6093
MWCNT (10:0.00) 10 00.00 0.00 0.00 0.000
MWCNT-CoTPP
(10:0.001)
10 0.671 0.56 0.084 0.671
MWCNT-CoTHPP
(10:0.001)
10 0.735 0.52 0.098 0.5145
MWCNT-CoTCPP
(10:0.001)
10 0.847 0.41 0.126 0.5929
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Fig. S1 IR spectra of the (a) MWCNT, (b) CoTHPP (c) MWCNT-CoTHPP, (d) CoTCPP,
(e) MWCNT-CoTCPP, (f) CoTPP, (g) MWCNT-CoTPP with the KBr pallets.
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C
N
O
Co
C
N O Co
Completespectra
Fig. S2(A) EDAX mapping of MWCNT-CoTHPP composite showing the element
distribution in the material.
6
C
N
O
Co
Completespectra
C
N O Co
Fig. S2(B) EDAX mapping of MWCNT-CoTCPP composite showing the element
distribution in the material.
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Fig. S2(C) EDAX mapping of MWCNT-CoTPP composite showing the elemental
distribution in the material.
C
N
O
Co
Completespectra
N O Co
C
8
0.1 0.2 0.3
50
60
70
Vo
lum
e @
ST
P (
cc/g
)
Relative Pressure, P/P0
MWCNT-CoTHPP
MWCNT
MWCNT-Co-TCPP
MWCNT-CoTPP
Fig. S3 Plot showing the nitrogen adsorption with MWCNT, MWCNT-CoTHPP,
MWCNT-CoTCPP and MWCNT-CoTPP materials.
9
Fig. S4 CV response of GC/MWCNT-CoTHPP (a), GC/MWCNT-CoTCPP (b) and
GC/MWCNT-CoTPP (c) at different scan rates 20, 50, 75, 100, 200, 300, 400,
500 mVs-1
in 0.1 M HClO4. (a’-c’) represents the respective plot of anodic (Ipa)
and cathodic (Ipc) peak current vs square root of scan rate.
0.0 0.4 0.8
-40
0
40
Cu
rren
t / A
E/V (vs RHE)
0.0 0.3 0.6 0.9
-40
0
40
80
Cu
rren
t / A
E/V (vs RHE)6 9 12 15 18
-6
2
4
C
urr
en
t / A
1/2
/ (mV/s)1/2
0.0 0.4 0.8-200
-100
0
100
200
Cu
rren
t / A
E/V (vs RHE)
6 9 12 15 18
-10
0
10
20
Cu
rren
t / A
1/2
/ (mV/s)1/2
4 8 12 16 20
-8
-4
0
4
Cu
rren
t / A
1/2
/ (mV/s)1/2
a a’
b b’
c c’
10
0.0 0.3 0.6
-0.6
-0.3
0.0
0.3
j/m
Acm
-2
E/V (vs RHE)0.0 0.4 0.8
-0.6
-0.3
0.0
0.3
j/m
Acm
-2
E/V (vs RHE)0.0 0.4 0.8
-0.6
-0.3
0.0
0.3
j/m
Acm
-2
E/V (vs RHE)0.2 0.4 0.6 0.8
-0.6
-0.3
0.0
0.3
j/m
Acm
-2
E/V (vs RHE)0.0 0.3 0.6
-0.6
-0.3
0.0
0.3
j/m
Acm
-2
E/V (vs RHE)
0.0 0.5 1.0
-1.8
-1.2
-0.6
0.0
j/m
Acm
-2
E/V (vs RHE)
0.0 0.4 0.8 1.2
-1.8
-1.2
-0.6
0.0
j/m
Acm
-2
E/V (vs RHE)
0.0 0.3 0.6 0.9 1.2
-1.8
-1.2
-0.6
0.0
j/m
Acm
-2
E/V (vs RHE)0.0 0.4 0.8 1.2
-1.8
-1.2
-0.6
0.0
j/m
Acm
-2
E/V (vs RHE)
0.6 0.8 1.0
-1.6
-0.8
0.0
j/m
Acm
-2
E/V (vs RHE)0.6 0.8 1.0
-1.6
-0.8
0.0
j/m
Acm
-2
E/V (vs RHE)0.6 0.8 1.0
-1.6
-0.8
0.0
j/m
Acm
-2
E/V (vs RHE)0.6 0.8 1.0
-1.6
-0.8
0.0
j/m
Acm
-2E/V (vs RHE)
0.4 0.8 1.2 1.6
-1.6
-0.8
0.0
j/m
Acm
-2
E/V (vs RHE)
ca b d e
a’ b’ c’ d’ e’
a” b” c” d” e”
0.0 0.4 0.8 1.2
-1.8
-1.2
-0.6
0.0
j/m
Acm
-2
E/V (vs RHE)
0.2 0.4 0.6 0.8 1.0
-0.6
-0.3
0.0
0.3
E / V (vs RHE)
e
Fig. S5 CV response of GC/MWCNT-CoTHPP (a, a’ and a”), GC/MWCNT-CoTCPP (b, b’ and b”), GC/MWCNT-CoTPP (c,
c’ and c”), GC/MWCNT (d, d’ and d”) and GC/Pt-C (e, e’ and e”) electrodes in 0.1 M HClO4 (a to e), 0.1 M PBS, pH
7.0 (a’ to e’) and in 0.1 M KOH (a” to e”) solutions saturated with either nitrogen (dashed line) or oxygen (solid line).
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-0.3 0.0 0.3 0.6 0.9
-0.20
-0.10
0.00
0.10
GC/CoTPP
GC/CoTHPP
GC/CoTCPP
j/m
Acm
-2
E/V (vs RHE)
0.6 0.8 1.0
-0.3
-0.2
-0.1
0.0
GC/CoTHPP
GC/CoTCPP
GC/CoTPP
j/m
Acm
-2
E/V (vs RHE)
a b
c
0.0 0.3 0.6 0.9 1.2
-0.3
-0.2
-0.1
0.0
j/m
Acm
-2
E/V (vs RHE)
GC/CoTCPP
GC/CoTHPP
GC/CoTPP
Fig. S6 CV response of different cobalt porphyrins films based electrodes in 0.1 M HClO4
(a), 0.1 M PBS pH 7.0 (b) and 0.1 M KOH (c) in oxygen saturated condition with
the scan rate of 20 mVs-1
.
12
-0.2 0.0 0.2 0.4 0.6
-100
0
100 dc
ba
Cu
rren
t / µ
A
Potential / V (vs Ag/AgCl)
Fig. S7 CV response in 0.1 M KCl with 10.0 mM K3[Fe(CN)6]/K4[Fe(CN)6] (1:1) for
active surface area determination. Where, a, b, c and d stands for GC/MWCNT-
CoTHPP, GC/MWCNT-CoTCPP, GC/MWCNT-CoTPP, and GC/MWCNT,
respectively.
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0.0 0.3 0.6
-4
-3
-2
-1
0
j/m
Acm
-2
E/V (vs RHE)
0.0 0.3 0.6 0.9-4
-3
-2
-1
0
j/m
Acm
-2
E/V (vs RHE)
0.0 0.3 0.6
-4
-3
-2
-1
0
j/m
Acm
-2
E/V (vs RHE)
0.02 0.04 0.06 0.08 0.100.2
0.4
0.6
0.8
1.0
1.2
j-1/m
Acm
-2
1/1/2
(rpm)1/2
0.02 0.04 0.06 0.08 0.10
0.4
0.8
1.2
1.6
j-1/m
Acm
-2
1/
(rpm)1/2
0.02 0.04 0.06 0.08 0.10
0.4
0.8
1.2
1.6
j-1/m
Acm
-2
1/1/2
(rpm)1/2
A B C
DE F
0
2500 rpm
0
2500 rpm
0
2500 rpm
Fig. S8 Current-potential curves at different rotation rates in 0.1 PBS pH 7.0 at a scan rate
of 10 mVs-1
in oxygen saturated condition (A-C) and the respective Koutecky-
Levich plots (D-F) for GC/MWCNT-CoTHPP (A, D), GC/MWCNT-CoTCPP (B,
E) and GC/MWCNT-CoTPP (C, F).
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0.4 0.6 0.8
-4
-2
0
j / m
Acm
-2
E/V (vs RHE)0.4 0.6 0.8 1.0
-4
-2
0
j/m
Acm
-2
E/V (vs RHE)
0.025 0.030 0.035 0.040
0.35
0.40
0.45
0.50
j-1/m
Acm
-2
1/
(rpm)1/2
0.02 0.03 0.04
0.3
0.4
0.5
j-1/m
Acm
-2
1/
(rpm)1/2
0.03 0.06 0.09
0.3
0.6
0.9
j-1/m
Acm
-2
1/1/2
(rpm)1/2
A B
D E
0.4 0.6 0.8 1.0 1.2
-4.0
-2.0
0.0
j/m
Acm
-2
E/V (vs RHE)
F
C
300
2500 rpm
300
2500 rpm
300
2500 rpm
Fig. S9 Current-potential curves at different rotation rates in 0.1 M KOH at a scan rate of
10 mVs-1
in oxygen saturated condition (A-C) and the respective Koutecky-
Levich plots (D-F) for GC/MWCNT-CoTHPP (A, D), GC/MWCNT-CoTCPP (B,
E) and GC/MWCNT-CoTPP (C, F).
15
-0.3 0.0 0.3 0.6
-4
-3
-2
-1
0
j/m
Acm
-2
E/V (vs RHE)
-0.3 0.0 0.3 0.6-4
-2
0
j/m
Acm
-2
E/V (vs RHE)
-0.4 -0.2 0.0 0.2 0.4 0.6
-3
-2
-1
0
j/m
Acm
-2
E/V (vs RHE)
0.0 0.2 0.4 0.6 0.8 1.0-4
-3
-2
-1
0
j/m
Acm
-2
E / V (vs RHE)
a b
c d
Fig. S10 LSV response for the stability of GC/MWCNT-CoTHPP (a), GC/MWCNT-
CoTCPP (b), GC/MWCNT-CoTPP (c) and GC/Pt-C (d) electrodes for ORR (at
1600 rpm) in 0.1 M HClO4 at the scan rate of 100 mVs-1
. Dotted lines represent
the first LSV response while solid lines represent LSV response after 3000 CV
cycles under the same conditions.
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2θ / degree 2θ / degree
2θ / degree
A B
20 40 600
400
800
a'
a
Inte
nsit
y
20 40 600
400
800
b'
b
Inte
nsit
y
C
20 40 600
400
800
c'
c
Inte
nsit
y
Fig. S11 XRD patterns of MWCNT-CoTHPP (A), MWCNT-CoTCPP (B) and MWCNT-
CoTPP (C) on ITO plates (thin film of the respective material is coated on ITO
plates) before (a, b, c) and after (a’, b’, c’) stability test (3000 CV cycles).
17
a b c
a’ b’ c’
1 μm
1 μm
1 μm
1 μm
1 μm
1 μm
Fig. S12 SEM images of MWCNT-CoTHPP (a, a’), MWCNT-CoTCPP (b, b’) and
MWCNT-CoTPP (c, c’) on ITO plates (thin film of the respective material is
coated on ITO plates) before (a, b, c) and after (a’, b’, c’) stability test (3000 CV
cycles).