Upload
others
View
3
Download
0
Embed Size (px)
Citation preview
Supporting information for
Remarkably improved oxygen evolution reaction activity of
cobalt oxides by Fe ion solution immersion process
Shencheng Pan1, Xin Mao2, Juan Yu1, Lin Hao5, Aijun Du2, Bing Li1,3,4,5,*
1. School of Physics and Electronic Information, Huaibei Normal University, Huaibei
235000, P. R. China
2. School of Chemistry and Physics and Center for Material Science, Queensland University
of Technology, Gardens Point Campus, Brisbane, QLD 4001, Australia
3. Anhui Province Key Laboratory of Pollutant Sensitive Materials and Environmental
Remediation, Huaibei Normal University, Huaibei 235000, P. R. China
4. Information College, Huaibei Normal University,Huaibei 235000, P. R. China
5. Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee
37996, USA
* Corresponding author. E-mail: [email protected]
200 400 600 800 1000 200 400 600 800 1000
(b)
Inte
nsi
ty (
a.u
.)
Raman shift (cm-1)
Co3O4
Fe-Co3O
4
(a)
Inte
nsi
ty (
a.u
.)
Raman shift (cm-1)
CoO
Fe-CoO
Fig. S1. Raman spectra of Co3O4, CoO, Fe-Co3O4 and Fe-CoO.
Electronic Supplementary Material (ESI) for Inorganic Chemistry Frontiers.This journal is © the Partner Organisations 2020
Fig. S2. TEM images of -Co(OH)2 nanoflower.
Fig. S3. TEM images of Co3O4 nanoparticles before Fe ion treatments.
Fig. S4. TEM images of CoO nanoparticles before Fe ion treatments.
Fig. S5. (a) High resolution TEM images of Fe-Co3O4, (b) the SAED pattern of Fe-Co3O4.
Fig. S6. (a) High resolution TEM images of Fe-CoO, (b) the SAED pattern of Fe-CoO.
Fig. S7. SEM image (a), elemental mapping of Co (b), O (c) and Fe (d) element in Fe-Co3O4.
Fig. S8. SEM image (a), elemental mapping of Co (b), O (c) and Fe (d) element in Fe-CoO.
810 800 790 780 810 800 790 780
810 800 790 780810 800 790 780
(d)(c)
Co3O
4
Fe-Co3O
4
Co 2p1/2
Co 2p3/2
Co 2p
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
(b)
Co 2p1/2
Co 2p3/2
Co 2p
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
CoO
Fe-CoO(a)
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
CoO
Co2+
Co2+
Co 2p3/2
Co 2p1/2
sat.
sat.
Co3+
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
Co3O
4
Co2+
Co3+
sat.sat.
Co2+
Co 2p3/2
Co 2p1/2
Co3+
Ratio: 56.5%
Fig. S9. (a) High resolution XPS spectrum of Co3O4 and Fe-Co3O4. (b) High resolution XPS
spectrum of CoO and Fe-CoO. (c) Fitting of Co 2p XPS spectrum for Co3O4, (d) fitting of Co 2p
XPS spectrum for CoO.
1.2 1.4 1.6 1.8
0
100
200
300
1.45
1.50
1.55
1.60
1.65
1.70
0.5 1.0 1.5
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. RHE)
Fe-Co3O
4
Fe-CoO
RuO2
NF
Log[J/(mA/cm2)]
Pote
nti
al (
V v
s. R
HE
)
Fe-Co3O
4
Fe-CoO
RuO2
NF
152 mV/dec
142 mV/dec
55 mV/dec
55 mV/dec
1 2 3 4200
300
400
500
(c)
(b)J=10 mA/cm
2
Over
po
ten
tial
(m
V)
Samples
280 mV296 mV
306 mV
451 mV
(a)
Fig. S10. (a) LSV curves of Fe-Co3O4, Fe-CoO, RuO2 and no-load Ni foam. (b) Overpotential
comparison histogram of Fe-Co3O4, Fe-CoO, RuO2 and no-load Ni foam at a current density of
10 mA/cm2. (c) Corresponding Tafel plots of the four prepared catalysts.
1.2 1.4 1.6 1.8
0
50
100
150
200
0 10 20 30 40 50 60 700
10
20
30
40
50 Initial
After 1000 cycles CV
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. RHE)
326 mV 343 mV
(b)
-Z"
(oh
m)
Z' (ohm)
Initial
After 1000 cycles CV
(a)
Fig. S11. Electrochemical testing of Fe-Co3O4 while the immersion concentration is 0.01 M (a)
LSV curves, (b) Nyquist plots with an initial and after 1000 cycles CV test.
1.2 1.4 1.6 1.8
0
50
100
150
200
0 10 20 30 40 500
5
10
15
20
25
30(b) Initial
After 1000 cycles CV
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. RHE)
314 mV325 mV
(a) Initial
After 1000 cycles CV
-Z"
(oh
m)
Z' (ohm) Fig. S12. Electrochemical testing of Fe-Co3O4 while the immersion concentration is 0.03 M (a)
LSV curves, (b) Nyquist plots with an initial and after 1000 cycles CV test.
1.2 1.4 1.6 1.8
0
50
100
150
200
0 10 20 30 40 50 60 700
10
20
30
40
(b) Initial
After 1000 cycles CV
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. RHE)
323 mV331 mV
(a) Initial
After 1000 cycles CV
-Z"
(oh
m)
Z' (ohm) Fig. S13. Electrochemical testing of Fe-Co3O4 while the immersion concentration is 0.04 M (a)
LSV curves, (b) Nyquist plots with an initial and after 1000 cycles CV test.
1.2 1.4 1.6 1.8
0
50
100
150
200
0 10 20 30 40 50 60 70 800
10
20
30
40
50
60(b) Initial
After 1000 cycles CV
Cu
rren
t D
en
sity
(m
A/c
m2)
Potential (V vs. RHE)
381 mV 387 mV
(a)
Initial
After 1000 cycles CV
-Z"
(ohm
)
Z' (ohm)
Fig. S14. Electrochemical testing of Fe-CoO while the immersion concentration is 0.1 M (a) LSV
curves, (b) Nyquist plots with an initial and after 1000 cycles CV test.
1.2 1.4 1.6 1.8
0
50
100
150
200
0 10 20 30 40 50 60 700
10
20
30
40
50(b)
340 mV
Initial
After 1000 cycles CV
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. RHE)
319 mV
(a) Initial
After 1000 cycles CV
-Z"
(oh
m)
Z' (ohm)
Fig. S15. Electrochemical testing of Fe-CoO while the immersion concentration is 0.03 M (a)
LSV curves, (b) Nyquist plots with an initial and after 1000 cycles CV test.
-0.6 -0.4 -0.2 0.0 1.2 1.4 1.6 1.8-400
-200
0
200
400
0.4 0.6 0.8 1.0 1.2 1.4
-0.25
-0.20
-0.15
-0.10
HER
=168 mV
HER
=224 mV
OER
=296 mV
Fe-Co3O
4
Fe-CoOC
urr
ent
Den
sity
(m
A/c
m2)
Potential (V vs. RHE)
OER
=280 mV
Pote
nti
al (
V v
s. R
HE
)
Log[J/(mA/cm2)]
Fe-Co3O
4
Fe-CoO
114 mV/dec
160 mV/dec
Tafel slope of HER(a) (b)
Fig. S16. (a) OER and HER curve of Fe-Co3O4 and Fe-CoO, (b) Tafel plots of Fe-Co3O4 and
Fe-CoO.
0.00 0.02 0.04 0.06 0.08 0.10-0.2
-0.1
0.0
0.1
0.2
0.00 0.02 0.04 0.06 0.08 0.10
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.00 0.02 0.04 0.06 0.08 0.10-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.00 0.02 0.04 0.06 0.08 0.10-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. AgCl)
Scan rate Scan rate
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. AgCl)
Scan rate
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. AgCl)
Scan rate(d)(c)
(b)
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. AgCl)
(a)
Fig. S17. CVs of Co3O4 (a), Fe-Co3O4 (b), CoO (c) and Fe-CoO (d) with increasing scan rates.
Fig. S18. SEM image (a), elemental mapping of Co (b), O (c) and Fe (d) element in Fe-Co3O4
after i-t test.
Fig. S19. SEM image (a), elemental mapping of Co (b), O (c) and Fe (d) element in Fe-CoO after
i-t test.
735 730 725 720 715 710 705 810 800 790 780 534 532 530 528
735 730 725 720 715 710 705 810 800 790 780 534 532 530 528
Fe 2p
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
After
Before
Co 2p
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
After
Before
O 1s
(d)
(c)(b)
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
After
Before
(a)
Fe 2p(f)(e)
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
After
Before
Co 2p
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
After
Before
O 1s
Inte
nsi
ty (
a.u.)
Binding Energy (eV)
Before
After
Fig. S20. High-resolution XPS spectrum of Fe 2p (a), Co 2p (b) and O 1s (c) for Fe-Co3O4 and Fe
2p (d), Co 2p (e) and O 1s (f) for Fe-CoO before (black line) and after (red line) i-t test.
0 5 10 15 20 25 300
5
10
15
20
0 10 20 30 400
5
10
15
20
25
30 Initial
After 1000 cycles CV
-Z"
(oh
m)
Z' (ohm)
Fe-Co3O
4 Fe-CoO
(b) Initial
After 1000 cycles CV
-Z"
(oh
m)
Z' (ohm)
(a)
Fig. S21. Nyquist plots of Fe-Co3O4 (a) and Fe-CoO (b) for initial and after 1000 cycles CV test.
0.00 0.02 0.04 0.06 0.08 0.10
-0.8
-0.4
0.0
0.4
0.8
20 40 60 80 100 120 140 160
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. AgCl)
Scan rate (b)
J
(mA
/cm
2)
Scan rate (mV/s)
3.92 mF/cm2
(a)
Fig. S22. (a) CV of Fe-Co3O4 with increasing scan rates after CV cycles (b) Cdl calculated value
of Fe-Co3O4 after CV cycles.
0.00 0.02 0.04 0.06 0.08 0.10
-0.8
-0.4
0.0
0.4
0.8
20 40 60 80 100 120 140 1600.2
0.4
0.6
0.8
1.0(b)
Scan rate
Cu
rren
t D
ensi
ty (
mA
/cm
2)
Potential (V vs. AgCl)
(a)
2.6 mF/cm2
J
(mA
/cm
2)
Scan rate (mV/s)
Fig. S23. (a) CV of Fe-CoO with increasing scan rates after 1000 CV cycles (b) Cdl calculated
value of Fe-CoO after CV cycles.
Table S1 The electrocatalytic OER activity of Fe-Co3O4 by different Fe ion concentrations in
soak solution
Fe ion concentrations in
soak solution
Overpotential
(mV)
Current density
@1.8 V (mA/cm2)
Charge transfer
resistance (Ω)
0.01 M (Initial) 343 (10 mA/cm2) 294 45.7
0.01 M (After 1000 CV) 326 (10 mA/cm2) 296 62.5
0.02 M (Initial) 280 (10 mA/cm2) 542 22.6
0.02 M (After 1000 CV) 263 (10 mA/cm2) 597 26.6
0.03 M (Initial) 325 (10 mA/cm2) 303 27.8
0.03 M (After 1000 CV) 314 (10 mA/cm2) 349 43.8
0.04 M (Initial) 331 (10 mA/cm2) 285 35.2
0.04 M (After 1000 CV) 323 (10 mA/cm2) 303 60.4
Table S2 The electrocatalytic OER activity of Fe-CoO by different Fe ion concentrations in soak
solution
Fe ion concentrations in
soak solution
Overpotential
(mV)
Current density
@1.8 V (mA/cm2)
Charge transfer
resistance (Ω)
0.01 M (Initial) 387 (50 mA/cm2) 365 41.9
0.01 M (After 1000 CV) 381 (50 mA/cm2) 398 63.8
0.02 M (Initial) 296 (10 mA/cm2) 480 29.6
0.02 M (After 1000 CV) 272 (10 mA/cm2) 539 33.1
0.03 M (Initial) 340 (10 mA/cm2) 269 51.4
0.03 M (After 1000 CV) 319 (10 mA/cm2) 354 62.5
Table S3 Comparison of OER performance of some cobalt oxide based electrocatalysts in
recently work.
Sample Electrolyte Current density
(mA/cm2) (mV)
Tafel slope
(mV/dec)
Fe-Co3O4 (This work) 1 M KOH 10 mA/cm2 280 55
Fe-CoO (This work) 1 M KOH 10 mA/cm2 296 55
RuO2 (This work) 1 M KOH 10 mA/cm2 306 142
Co3O4-MWCNT1 1 M KOH 10 mA/cm2 320 69
Co3O4-B2 1 M KOH 10 mA/cm2 318 57.6
S-CoO/Co3O43 1 M KOH 10 mA/cm2 275 92
Hemoglobin modified
Co3O4-g-C3N44
0.5 M KOH 10 mA/cm2 370 66
Co3O4 nanoflowers5 1 M KOH 10 mA/cm2 297 79.1
Co3O4/CoO6 1 M KOH 10 mA/cm2 302 68.6
References
1. X, Zhang, Y. S. Chen, P. V. Kamat, S Ptasinska, Probing Interfacial Electrochemistry on a
Co3O4 Water Oxidation Catalyst Using Lab-Based Ambient Pressure X-Ray Photoelectron
Spectroscopy. J. Phys. Chem. C 2018, 122, 13894-13901.
2. R. Wei, M. Fang, G. Dong, C. Lan, L. Shu, H. Zhang, X. Bu, J. C. Ho, High-Index Faceted
Porous Co3O4 Nanosheets with Oxygen Vacancies for Highly Efficient Water Oxidation. ACS Appl.
Mater. Interfaces 2018, 10, 7079-7086.
3. T. Sun, P. Liu, Y. Zhang, Z. Chen, C. Zhang, X. Guo, C. Ma, Y. Gao, S. Zhang, Boosting the
Electrochemical Water Splitting on Co3O4 through Surface Decoration of Epitaxial S-Doped Coo
Layers. Chem. Eng. J. 2020, 390, 124591.
4. C. Leal-Rodriguez, D. Rodriguez-Padron, Z. A. Alothman, M. Cano, J. J. Giner-Casares, M. J.
Munoz-Batista, S. M. Osman, R. Luque, Thermal and Light Irradiation Effects on the
Electrocatalytic Performance of Hemoglobin Modified Co3O4-g-C3N4 Nanomaterials for the
Oxygen Evolution Reaction. Nanoscale 2020, 12, 8477-8484.
5. J. Du, C. Li, Q. Tang, Oxygen Vacancies Enriched Co3O4 Nanoflowers with Single Layer
Porous Structures for Water Splitting. Electrochim. Acta 2020, 331, 135456.
6. Z. Liu, Z. Xiao, G. Luo, R. Chen, C. L. Dong, X. Chen, J. Cen, H. Yang, Y. Wang, D. Su, Y.
Li, S. Wang, Defects-Induced in-Plane Heterophase in Cobalt Oxide Nanosheets for Oxygen
Evolution Reaction. Small 2019, 15, 1904903.