Cobalt Hydroxide/Oxide Hexagonal RingâGraphene Hybrids through ...
Supporting Information
Cobalt Hydroxide/Oxide Hexagonal Ring–Graphene Hybrids through Chemical Etching of Metal Hydroxide Platelets by Graphene Oxide: Energy Storage Applications C. Nethravathi,†,* Catherine R. Rajamathi,‡ Michael Rajamathi,‡,* Xi Wang, †,* Ujjal K. Gautam,# Dmitri Golberg,†,* Yoshio Bando† †
World Premier International (WPI) Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan ‡
Materials Research Group, Department of Chemistry, St. Joseph’s College, 36 Lalbagh Road, Bangalore 560 027, India
#
New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
Corresponding authors: [email protected], [email protected], [email protected], [email protected]
Figure S1 High magnification bright field TEM images of Co3O4 hexagonal ring–graphene hybrid.
Figure S2 Bright field TEM image (a) and HRTEM image (SAED shown as inset) (b) of the CoO hexagonal ring–graphene hybrid.
Figure S3 XRD patterns of pristine β-Ni0.33Co0.66(OH)2 hexagonal platelets (a), βNi0.33Co0.66(OH)2 hexagonal ring–GO hybrid (b) and NiCo2O4 hexagonal ring–graphene hybrid (c) obtained by heating the hydroxide hybrid at 500 oC in air.
Figure S4 Electron energy loss (EELS) spectrum of Co3O4 hexagonal ring–graphene hybrid.
Binding Energies (eV)
Sample
graphene oxide
β-Co(OH)2 hexagonal rings – graphene oxide hybrid Co3O4 hexagonal rings – graphene hybrid
C 1s
Co 2p 2
284.50 286.07 287.46 289.14
[-C-C-(sp )] [-C-OH] [-C=O] [-COOH]
284.50 286.27 287.35 288.82
[-C-C-(sp )] [-C-OH] [-C=O] [-COOH]
2
781.19 & 797.43
2
284.50 [-C-C-(sp )] 286.00 [-C-OH] 288.28 [-COOH]
780.44 & 796.11
Figure S5 Core level Co 2p XPS spectrum of β-Co(OH)2 hexagonal ring–graphene oxide (a) and Co3O4 hexagonal ring–graphene (b) hybrids. The binding energies are summarized in the table. In the case of (a), Co 2p3/2 (781.19 eV) and Co 2p1/2 (797.43 eV) parts accompanied by satellite lines are characteristic of brucite like β-Co(OH)2.65 The spin-orbit splitting value is calculated to be 16.24 eV. In the case of (b), Co 2p3/2 (780.44 eV) and Co 2p1/2 (796.11 eV) with weaker satellite lines and a spin-orbit splitting value of 15.67 eV confirm the presence of Co3O4.65
Figure S6 SEM image of the β-Co(OH)2 hexagonal platelet–graphite mixture.
Table S1 The amount of GO used and the pH of the supernatant in the formation of β-Co(OH)2– graphene oxide hybrids. β-Co(OH)2 mass (mg)
~ 80
GO
pH of the pH of the pH of the supernatant mass (mg) dispersion dispersion 100 3.6 7.4 200 3.0 6.8 7.5 300 2.9 6.6 400 2.7 6.2
(d) pristine oxides
BET surface area (m2/g)
pore volume average pore (cc/g) diameter (Å)
Co3O4 porous hexagons
221.6
0.24
43.37
CoO porous hexagons
65.14
0.18
113.6
NiCo2O4 porous hexagons
97.18
0.26
35.27
Figure S7 Nitrogen adsorption–desorption curves of pristine porous hexagons of Co3O4 (a) CoO (b) and NiCo2O4 (c). The BET surface area analysis of the oxides is summarized in table (d)
Table S2 Comparison of specific capacity of Co3O4 hexagonal ring–graphene hybrid with literature results on Co3O4–graphene hybrids.
hybrid
current density capacity (mAhg-1) (mAg-1) after (x) cycles
reference
Co3O4 porous nanosheets – graphene
143
630 (50)
1
Co3O4 hollow nanoparticles – graphene
74
760 (20)
2
Co3O4 nanoparticles – graphene
74
1000 (130)
3
Co3O4 nanoparticles – graphene
40
860 (120)
4
Co3O4 nanoparticles – graphene
200
740 (60)
5
Co3O4 rings – graphene
178
748 (50)
present work
1. Sun, H.; Liu, Y.; Yu, Y.; Ahmade, M.; Nan, D.; Zhu, J. Mesoporous Co3O4 Nanosheets3D Graphene Networks Hybrid Materials for High-Performance Lithium Ion Batteries. Electrochim. Acta 2014, 118, 1-9. 2. Yang, S.; Cui, G.; Pang, S.; Cao, Q.; Kolb, U.; Feng, X.; Maier, J.; Mullen, K. Fabrication of Cobalt and Cobalt Oxide/Graphene Composites: Towards HighPerformance Anode Materials for Lithium Ion Batteries. ChemSusChem 2010, 3, 236239. 3. Yang, S.; Feng, X.; Ivanovici, S.; Mullen, K. Fabrication of Graphene-Encapsulated Oxide Nanoparticles: Towards High-Performance Anode Materials for Lithium Storage. Angew. Chem. Int. Ed. 2010, 49, 8408 –8411. 4. Pan, L.; Zhao, H.; Shen, W.; Dong, X.; Xu, J. Surfactant – Assisted Synthesis of a Co3O4 / Reduced Graphene Oxide Composites as A Superior Anode Material for Li-Ion Batteries. J. Mater. Chem. A, 2013, 1, 7159-7166. 5. Li, B.; Cao, H.; Shao, J.; Li, G.; Qu, M.; Yin, G. Co3O4@Graphene Composites as Anode Materials for High-Performance Lithium Ion Batteries. Inorg. Chem. 2011, 50, 1628– 1632.
Table S3 Comparison of specific capacity of CoO hexagonal ring–graphene hybrid with literature results on CoO–graphene hybrids.
hybrid
current density capacity (mAhg-1) reference (mAg-1) after (x) cycles 1592 (50)
1
CoO quantum dots – graphene
50
CoO nanosheets – graphene
100
640 (150)
2
CoO rings – graphene
143
644 (50)
present work
1. Peng, C.; Chen, B.; Qin, Y.; Yang, S.; Li, C.; Zuo, Y.; Liu, S.; Yang, J. Facile Ultrasonic Synthesis of CoO Quantum Dot / Graphene Nanosheet Composites With High Lithium Storage Capacity. ACS Nano, 2012, 6, 1074-1081. 2. Huang, X.-l.; Wang, R.-Z.; Xu, D.; Wang, Z.-l.; Wang, H.-G.; Xu, J.-J.; Wu, Z.; Liu, Q. C.; Zhang, Y.; Zhang, X.-B. Homogeneous CoO on Graphene for Binder-Free and Ultralong-Life Lithium Ion Batteries. Adv. Funct. Mater. 2013, 23, 4345-4353.
Table S4 Comparison of specific capacity of NiCo2O4 hexagonal ring–graphene hybrid with literature results on NiCo2O4–graphene hybrids.
hybrid
current specific reference density (Ag-1) capacitance (Fg-1)
NiCo2O4 nanowires – graphene
1
737
1
NiCo2O4 nanorods – graphene
1
1002
2
NiCo2O4 nanowires – graphene
1
1050
3
0.5
1222
4
1
1337
present work
NiCo2O4 nanocrystals – graphene NiCo2O4 rings – graphene
1. He, G.; Wang, L.; Chen, H.; Sun, X.; Wang, X. Preparation and Performance of NiCo2O4 Nanowires-Loaded Graphene As Supercapacitor Material. Mater. Lett. 2013, 98, 164-167. 2. Zhang, G.; Lou, X. W. Controlled Growth of NiCo2O4 Nanorods and Ultrathin Nanosheets on Carbon Nanofibers for High-performance Supercapacitors. Sci. Rep. 2013, 3, 1470-1476. 3. Wang, H.; Wang, H.; Hu. Z.; Chang, Y.; Chen, Y.; Wu, H.; Zhang, Z.; Yang, Y. Design and Synthesis of NiCo2O4–Reduced Graphene Oxide Composites for High Performance Supercapacitors. J. Mater. Chem. 2011, 21, 10504-10511. 4. Wang, X.; Liu, W. S.; Lu, S.; Lee, P. S. Dodecyl Sulfate-Induced Fast Faradic Process In Nickel Cobalt Oxide–Reduced Graphite Oxide Composite Material and Its Application For Asymmetric Supercapacitor Device. J. Mater. Chem. 2012, 22, 23114-23119.
Cobalt Hydroxide/Oxide Hexagonal Ring–Graphene Hybrids through Chemical Etching of Metal Hydroxide Platelets by Graphene Oxide: Energy Storage Applications C. Nethravathi,†,* Catherine R. Rajamathi,‡ Michael Rajamathi,‡,* Xi Wang, †,* Ujjal K. Gautam,# Dmitri Golberg,†,* Yoshio Bando† †
World Premier International (WPI) Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan ‡
Materials Research Group, Department of Chemistry, St. Joseph’s College, 36 Lalbagh Road, Bangalore 560 027, India
#
New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
Corresponding authors: [email protected], [email protected], [email protected], [email protected]
Figure S1 High magnification bright field TEM images of Co3O4 hexagonal ring–graphene hybrid.
Figure S2 Bright field TEM image (a) and HRTEM image (SAED shown as inset) (b) of the CoO hexagonal ring–graphene hybrid.
Figure S3 XRD patterns of pristine β-Ni0.33Co0.66(OH)2 hexagonal platelets (a), βNi0.33Co0.66(OH)2 hexagonal ring–GO hybrid (b) and NiCo2O4 hexagonal ring–graphene hybrid (c) obtained by heating the hydroxide hybrid at 500 oC in air.
Figure S4 Electron energy loss (EELS) spectrum of Co3O4 hexagonal ring–graphene hybrid.
Binding Energies (eV)
Sample
graphene oxide
β-Co(OH)2 hexagonal rings – graphene oxide hybrid Co3O4 hexagonal rings – graphene hybrid
C 1s
Co 2p 2
284.50 286.07 287.46 289.14
[-C-C-(sp )] [-C-OH] [-C=O] [-COOH]
284.50 286.27 287.35 288.82
[-C-C-(sp )] [-C-OH] [-C=O] [-COOH]
2
781.19 & 797.43
2
284.50 [-C-C-(sp )] 286.00 [-C-OH] 288.28 [-COOH]
780.44 & 796.11
Figure S5 Core level Co 2p XPS spectrum of β-Co(OH)2 hexagonal ring–graphene oxide (a) and Co3O4 hexagonal ring–graphene (b) hybrids. The binding energies are summarized in the table. In the case of (a), Co 2p3/2 (781.19 eV) and Co 2p1/2 (797.43 eV) parts accompanied by satellite lines are characteristic of brucite like β-Co(OH)2.65 The spin-orbit splitting value is calculated to be 16.24 eV. In the case of (b), Co 2p3/2 (780.44 eV) and Co 2p1/2 (796.11 eV) with weaker satellite lines and a spin-orbit splitting value of 15.67 eV confirm the presence of Co3O4.65
Figure S6 SEM image of the β-Co(OH)2 hexagonal platelet–graphite mixture.
Table S1 The amount of GO used and the pH of the supernatant in the formation of β-Co(OH)2– graphene oxide hybrids. β-Co(OH)2 mass (mg)
~ 80
GO
pH of the pH of the pH of the supernatant mass (mg) dispersion dispersion 100 3.6 7.4 200 3.0 6.8 7.5 300 2.9 6.6 400 2.7 6.2
(d) pristine oxides
BET surface area (m2/g)
pore volume average pore (cc/g) diameter (Å)
Co3O4 porous hexagons
221.6
0.24
43.37
CoO porous hexagons
65.14
0.18
113.6
NiCo2O4 porous hexagons
97.18
0.26
35.27
Figure S7 Nitrogen adsorption–desorption curves of pristine porous hexagons of Co3O4 (a) CoO (b) and NiCo2O4 (c). The BET surface area analysis of the oxides is summarized in table (d)
Table S2 Comparison of specific capacity of Co3O4 hexagonal ring–graphene hybrid with literature results on Co3O4–graphene hybrids.
hybrid
current density capacity (mAhg-1) (mAg-1) after (x) cycles
reference
Co3O4 porous nanosheets – graphene
143
630 (50)
1
Co3O4 hollow nanoparticles – graphene
74
760 (20)
2
Co3O4 nanoparticles – graphene
74
1000 (130)
3
Co3O4 nanoparticles – graphene
40
860 (120)
4
Co3O4 nanoparticles – graphene
200
740 (60)
5
Co3O4 rings – graphene
178
748 (50)
present work
1. Sun, H.; Liu, Y.; Yu, Y.; Ahmade, M.; Nan, D.; Zhu, J. Mesoporous Co3O4 Nanosheets3D Graphene Networks Hybrid Materials for High-Performance Lithium Ion Batteries. Electrochim. Acta 2014, 118, 1-9. 2. Yang, S.; Cui, G.; Pang, S.; Cao, Q.; Kolb, U.; Feng, X.; Maier, J.; Mullen, K. Fabrication of Cobalt and Cobalt Oxide/Graphene Composites: Towards HighPerformance Anode Materials for Lithium Ion Batteries. ChemSusChem 2010, 3, 236239. 3. Yang, S.; Feng, X.; Ivanovici, S.; Mullen, K. Fabrication of Graphene-Encapsulated Oxide Nanoparticles: Towards High-Performance Anode Materials for Lithium Storage. Angew. Chem. Int. Ed. 2010, 49, 8408 –8411. 4. Pan, L.; Zhao, H.; Shen, W.; Dong, X.; Xu, J. Surfactant – Assisted Synthesis of a Co3O4 / Reduced Graphene Oxide Composites as A Superior Anode Material for Li-Ion Batteries. J. Mater. Chem. A, 2013, 1, 7159-7166. 5. Li, B.; Cao, H.; Shao, J.; Li, G.; Qu, M.; Yin, G. Co3O4@Graphene Composites as Anode Materials for High-Performance Lithium Ion Batteries. Inorg. Chem. 2011, 50, 1628– 1632.
Table S3 Comparison of specific capacity of CoO hexagonal ring–graphene hybrid with literature results on CoO–graphene hybrids.
hybrid
current density capacity (mAhg-1) reference (mAg-1) after (x) cycles 1592 (50)
1
CoO quantum dots – graphene
50
CoO nanosheets – graphene
100
640 (150)
2
CoO rings – graphene
143
644 (50)
present work
1. Peng, C.; Chen, B.; Qin, Y.; Yang, S.; Li, C.; Zuo, Y.; Liu, S.; Yang, J. Facile Ultrasonic Synthesis of CoO Quantum Dot / Graphene Nanosheet Composites With High Lithium Storage Capacity. ACS Nano, 2012, 6, 1074-1081. 2. Huang, X.-l.; Wang, R.-Z.; Xu, D.; Wang, Z.-l.; Wang, H.-G.; Xu, J.-J.; Wu, Z.; Liu, Q. C.; Zhang, Y.; Zhang, X.-B. Homogeneous CoO on Graphene for Binder-Free and Ultralong-Life Lithium Ion Batteries. Adv. Funct. Mater. 2013, 23, 4345-4353.
Table S4 Comparison of specific capacity of NiCo2O4 hexagonal ring–graphene hybrid with literature results on NiCo2O4–graphene hybrids.
hybrid
current specific reference density (Ag-1) capacitance (Fg-1)
NiCo2O4 nanowires – graphene
1
737
1
NiCo2O4 nanorods – graphene
1
1002
2
NiCo2O4 nanowires – graphene
1
1050
3
0.5
1222
4
1
1337
present work
NiCo2O4 nanocrystals – graphene NiCo2O4 rings – graphene
1. He, G.; Wang, L.; Chen, H.; Sun, X.; Wang, X. Preparation and Performance of NiCo2O4 Nanowires-Loaded Graphene As Supercapacitor Material. Mater. Lett. 2013, 98, 164-167. 2. Zhang, G.; Lou, X. W. Controlled Growth of NiCo2O4 Nanorods and Ultrathin Nanosheets on Carbon Nanofibers for High-performance Supercapacitors. Sci. Rep. 2013, 3, 1470-1476. 3. Wang, H.; Wang, H.; Hu. Z.; Chang, Y.; Chen, Y.; Wu, H.; Zhang, Z.; Yang, Y. Design and Synthesis of NiCo2O4–Reduced Graphene Oxide Composites for High Performance Supercapacitors. J. Mater. Chem. 2011, 21, 10504-10511. 4. Wang, X.; Liu, W. S.; Lu, S.; Lee, P. S. Dodecyl Sulfate-Induced Fast Faradic Process In Nickel Cobalt Oxide–Reduced Graphite Oxide Composite Material and Its Application For Asymmetric Supercapacitor Device. J. Mater. Chem. 2012, 22, 23114-23119.
