Supplementary information for:
Fabrication of Large-Area and High Crystalline Photoreduced
Graphene Oxide Films via Reconstructed Two-Dimensional
Multilayer Structures
1
1
Yuanlong Shao, 1Hongzhi Wang*, 1Qinghong Zhang, and 2Yaogang Li*
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of
Material Science and Engineering, Donghua University, Shanghai, 201620, China
2
Engineering Research Center of Advanced Glasses Manufacturing Technology, Ministry of
Education, Donghua University, Shanghai, 201620, China
Digital images of GO gels and GO films……………………………………………………….…...2
AFM measurement of GO sheets and PRGO film.…………………………………………….…..3
Cross-section SEM of crimped PRGO films…………………………………………………….….5
Side view SEM images of cross-section morphologies of GO films, PRGO, and CCG films……6
TEM images of GO films…………………………………………………………………………….7
Digital images of PRGO films and GO films after 30s ultrasonication…………………………...8
Raman and FTIR spectroscopy measurement of GO films, PRGO films and CCG films………9
Thermal imagery measurement of GO films under illumination………………………………..10
Dielectric constant measurement configuration……………………………………………….….11
Comparison of the capacitance performances……………………………………………….……12
References……………………………………………….……………………………….…….……15
1
Digital images of GO gels and GO films
Figure S1. (A, C) The large-area GO films directly coated on Cu foil and freestanding films peeled
from the substrate without photoreduction and exhibited bright brown. (B) The digital photograph of
GO solution and GO gels on an inclined flat plate. The phenomenon of stagnation flow indicates the
high viscosity of GO gel.
2
AFM measurement of GO sheets and PRGO films
Figure S2. (A) AFM image of GO sheets. (B) The height profile of GO sheet. (C) The height
distribution diagram of the AFM image.
3
Figure S3. (A-C and E-G) Amplitude, topography images and height profiles of PRGO films with
different area range. Figure (A-C) tested with area range of 4.2×4.2 μm, which is same as the test
area range of GO sheets. Figure (E-G) tested with area range of 8.4×8.4 μm. (D) SEM image of the
surface of PRGO films.
4
Cross-section SEM of crimped PRGO films
Figure S4. Liquid nitrogen release gas to make the PRGO sheets crimped like wave. This
phenomenon also demonstrates the intensive stack of graphene platelets in the thin films.
5
Side view SEM images of cross-section morphologies of GO films, PRGO, and
CCG films
Figure S5. Side view SEM images of cross-section morphologies of (A) GO films, (B) PRGO films
and (C) CCG films; (D, E and F) images under higher magnification.
6
TEM images of GO films
Figure S6. TEM (A-C) and HRTEM (D) images of GO films made with the same process as that of
PRGO without photoreduction.
7
Digital images of PRGO films and GO films after 30s ultrasonication
Figure S7. Digital images of PRGO films and GO films after 30s ultrasonication immersed in water.
8
Raman and FTIR spectroscopy measurement of GO films, PRGO films and CCG
films
Figure S8. (A) Comparison of FTIR spectra for GO, PRGO films and CCG. (B) Raman spectra for
GO, PRGO films and CCG.
9
Thermal imagery measurement of GO films under illumination
Figure S9. (A) The thermal image of GO film under illumination for 1h. The difference in colors is
due to IR camera automatically adjusting to relative temperature. The inset image is the digital photo
of the GO film. (B) The temperature profiles of GO films on the indicated line.
10
Dielectric constant measurement configuration
Figure S10. Schematic illustrating the dielectric constant measurement configuration.
From a microscopic point of view, the increase capacitance is generated from the polarization of the
medium in which positive and negative charges are displaced with respect to their equilibrium
positions. After photoreduction, the conductivity of PRGO films was increased. The higher
conductivity of PRGO films increase the density of the accumulated charge carriers at the interfaces
between conductive PRGO platelets and neighboring partical reduced nonconductive PRGO films
with remaining oxygen-containing groups, leading to an increased interfacial polarization that would
contribute to an increased dielectric constant. The dielectric constant was studied with the
measurement configuration shown in Figure S10 at a driving voltage of 0.1 V and a frequency of 1
kHz. The dielectric constant of these films can be calculated according to the following equation:
=
(1)
where C is the measured capacitance, d is the distance between the Cu foil and FTO electrode, A is
the overlapping surface area of the two conductive plates, and ε0, the vacuum permittivity, is
8.85×10-12 F m-1. As shown in Table S1, the dielectric constants (εr) of the graphene, GO, and PRGO
films were approximate 0.9, 9 and 18, respectively, at 1 kHz. Furthermore, from a device perspective,
11
the PRGO films can be viewed as dielectric medium between the parallel current collectors.
According to the familiar parallel plate capacitor equation, the dielectric constant of PRGO films as
it should be an important parameter to determine the capacitance of the electrode materials. Thus, we
believe that the increase of dielectric constant, which induced by interfacial polarization inside the
PRGO film is another crucial factor to enhance the electrochemical performance of PRGO films.
Table S1 Comparison of the dielectric constant of the PRGO, GO, and CCG films.
Sample
C(nF)
εr
PRGO
1.6-2.2
13.6-18.6
GO
0.7-1.1
5.9-9.3
GR
0.094-0.11
0.8-0.93
12
Comparison of the capacitance performances
Table S2. Comparison of the capacitance performances of the supercapacitors based on the PRGO films and those
of other pure chemically converted graphene-based electrodes.
Materials
Specific Capacitance (F/g)
Rate
(electrolyte)
Capability
Photoreduced graphene oxide 275 (Na2SO4)
61% (1V/s)
films
Ref.
Present
work
3D Graphene hydrogel films
186 (H2SO4)
70% (20A/g)
[S1]
Pillared graphene paper
138 (KOH)
58% (0.5V/s)
[S2]
Self-stacked, solated
215 (H2SO4)
72.6%
[S3]
graphene films
Functionalized reduced
(1080A/g)
118.5 (Nafion)
90% (30A/g)
[S4]
120 (TEABF4/AN)
~
[S5]
110 (H2SO4)
~
[S6]
172 (H2SO4)
64% (100A/g)
[S7]
203.2 (H2SO4)
61% (200A/g)
[S8]
265 (organic electrolyte)
43%
[S9]
graphene oxide thin films
Activated reduced graphene
oxide films
Reduced graphene oxide
foam
Folded structured graphene
paper
Liquid electrolyte-mediated
chemically converted
graphene films
Laser-scribed graphene
(1000A/g)
Graphene–cellulose paper
120 (H2SO4)
~
[S10]
Macroporous ‘bubble’
92.7 (KOH)
67.9% (1V/s)
[S11]
~
[S12]
graphene film
Reduced multilayer graphene 247.3 (H3PO4)
oxide
13
Ultrathin, transparent, and 111 (KCl)
75% (0.2 V/s)
[S13]
~
[S14]
flexible graphene films
Graphene-cellulose paper
120 (H2SO4)
14
Table S3. Comparison of the capacitance performances of the supercapacitors based on the PRGO films and those
of doped graphene-based electrodes.
Materials
Specific Capacitance (F/g)
Rate
(electrolyte)
Capability
Photoreduced graphene oxide 275 (Na2SO4)
61% (1V/s)
films
Ref.
Presen
t work
Hydroquinone functionalized 441 (H2SO4)
80% (20A/g)
[S15]
84% (0.5 V/s)
[S16]
58% (33 A/g)
[S17]
56% (0.1 V/s)
[S18]
74% (1 V/s)
[S19]
53% (10 A/g)
[S20]
graphene hydrogels
Nitrogen doped 3D graphene 454 (LiClO4)
framework
Nitrogen-doped graphene
282 (KOH)
Nitrogen and boron co-doped 237 (H2SO4)
graphene hydrogels
Crumpled
Nitrogen-Doped 248.4 ([Bu4N]BF4/AC)
Graphene
Nitrogen-doped graphene
326 (KOH)
15
References:
[S1] Y. X. Xu, Z. Y. Lin, X. Q. Huang, Y. Liu, Y. Huang, X. F. Duan, ACS Nano 2013 , 7, 4042.
[S2] G. K. Wang, X. Sun, F. Y. Lu, H. T. Sun, M. P. Yu, W. L. Jiang, C. S. Liu, J. Lian, Small 2012, 8,
452.
[S3] X. W. Yang, J. W. Zhu, L. Qiu, D. Li, Adv. Mater. 2011, 23, 2833.
[S4] B. G. Choi, J. Hong, W. H. Hong, P. T. Hammond, H. Park, ACS Nano 2011, 5, 7205.
[S5] L. L. Zhang, X. Zhao, M. D. Stoller, Y. Zhu, H. Ji, S. Murali, Y. Wu, S. Perales, B. Clevenger,
R. S. Ruoff, Nano Lett. 2012, 12, 1806.
[S6] Z. Niu, J. Chen, H. H. Hng, J. Ma, X. Chen, Adv. Mater. 2012, 24, 4144.
[S7] F. Liu, S. Song, D. Xue, H. Zhang, Adv. Mater. 2012, 24, 1089.
[S8] X. Yang, C. Cheng, Y. Wang, L. Qiu, D. Li, Science 2013, 341, 534.
[S9] M. F. El-Kady, V. Strong, S. Dubin, R. B. Kaner, Science 2012, 335, 1326.
[S10] Z. Weng, Y. Su, D. W. Wang, F. Li, J. Du, H. M. Cheng, Adv. Energy Mater. 2011, 1, 917.
[S11]C. M. Chen, Q. Zhang, C. H. Huang, X. C. Zhao, B. S. Zhang, Q. Q. Kong, M. Z. Wang, Y. G.
Yang, R. Cai and D. Sheng Su, Chem. Commun. 2012, 48, 7149.
[S12] J. J. Yoo, K. Balakrishnan, J. Huang, V. Meunier, B. G. Sumpter, A. Srivastava, M. Conway,
A. L. Mohana Reddy, J. Yu, R. Vajtai and P. M. Ajayan, Nano Lett. 2011, 11, 1423.
[S13] A. Yu, I. Roes, A. Davies and Z. Chen, Appl. Phys. Lett. 2010, 96, 253105.
[S14] Z. Weng, Y. Su, D. W. Wang, F. Li, J. Du and H. M. Cheng, Adv. Energy Mater. 2011, 1, 917.
[S15] Y. Xu, Z. Lin, X. Huang, Y. Wang, Y. Huang and X. Duan, Adv. Mater. 2013, 25, 5779.
[S16] Y. Zhao, C. G. Hu, Y. Hu, H. H. Cheng, G. Q. Shi, L. T. Qu, Angew. Chem. Int. Ed. 2012, 51,
11371.
[S17] H. M. Jeong, J. W. Lee, W. H. Shin, Y. J. Choi, H. J. Shin, J. K. Kang, J. W. Choi, Nano Lett.
2011, 11, 2472.
[S18] Z. S. Wu, A. Winter, L. Chen, Y. Sun, A. Turchanin, X. L. Feng, K. Müllen, Adv. Mater. 2012,
24, 5130.
[S19] Z. H. Wei, X. C. Wang, S. Mao, Z. Bo, H. Kim, C. M. Cui, G. H. Lu, X. L. Feng, J. H. Chen.
Adv. Mater. 2012, 24, 5610.
[S20] L. Sun, L. Wang, C. G. Tian, T. X. Tan, Y. Xie, K. Y. Shi, M. T. Li, H. G. Fu, RSC Adv. 2012,
16
2, 4498.
17