Supplementary Information
Stable dispersions of graphene and highly conducting graphene films: a new approach to creating colloids of graphene monolayers Yao Chen, Xiong Zhang, Peng Yu and Yanwei Ma*
Institute of Electrical Engineering, Chine Academy of Sciences, Beijing 100190, People’s Republic of China.
1. Synthesis of Graphite Oxide (GO)
Graphite oxide (GO) was prepared by natural graphite as the modified Hummers’ method. In a typical reaction, 1 g of natural graphite, 1 g of NaNO3 and 46 mL of concentrated H2SO4were stirred together in an ice bath for 4 h. Next, 6 g of KMnO4 was added slowly. Once mixed, the ice bath was removed and the suspension was stirred for 2 h. After adding 92 mL of pure water dropwi, the suspension was heated in a water bath at 98 o C for 15 min. Then the suspension was further treated with 200 mL of warm water and 20 mL of H2O2 (30%) in quence. The mixture was centrifuged at 4000 rpm and washed with HCl and water. Finally, GO was dried at 50 o C for 48 h.
2. Instruments
灯笼制作X-ray diffraction (XRD) analys were performed using a X' Pert Pro system with Cu KĮ radiation (Ȝ =1.54060 Å) operated at 40 kV and 40 mA. The
morphologies of the graphene film were investigated by JSM 6700-F FESEM (JEOL). Transmission electron microscopy (TEM) and lected area electron diffraction (SAED) studies were carried out using a TECNAI F30 TEM operating at an accelerating voltage of 300 kV. Atomic force microscopic (AFM) images were taken out using a Nanoscope III MultiMode SPM (Digital Instruments) operated in tapping mode in conjunction with a V-shaped tapping tip (Applied Nanostructures SPM model: ACTA). The images were taken at a scan rate of 2 Hz. X-rays photoelectron spectroscopy (XPS) spectrums were recorded on a PHI Quantear SXM (ULV AC-PH INC) which ud Al as anode probe in 6.7×10-8 Pa. Raman spectra were obtained on a RM 2000 microscopic confocal Raman spectrometer (Renishaw in Via Plus, England) employing a 514 nm lar beam. Fourier transform infrared spectroscopy (FTIR) spectrums were measured using a Nicolet IR100 FT-IR spectrometer with pure KBr as the background. UV-vis spectrums were detected using Ultraviolet spectrophotometer (Hitachi UV2800).
3. XRD
The XRD patterns of GO, cleaned G and G film on ITO are shown in Fig. S1. The peak of GO at 10-11° disappears and the board peaks are obrved in both G and its film on ITO, confirming that GO was reduced. The remained peaks in the graphene film are consistent with the ones of the ITO.
4. XPS
Fig. S2a shows the full XPS spectrums of GO and cleaned G. Through analyzing the N1s of the cleaned G in Fig. S2b, the main peak of N is attributed to “graphene N” (398.1 eV) according to the standard spectrums and the other peak is possibly associated with N-H (399.3 eV) from absorption of oxidation product of para-phenylene diamine (OPPD).臂部减肥
Fig. S1
XRD patterns of GO, cleaned G and G film on ITO.
Fig. S2 XPS spectrums and analysis.
(a) the full XPS spectrums of GO and cleaned G ,
(b) N1s XPS of cleaned G
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5. FTIR
The FTIR spectrum of cleaned G and GO are prented in Fig. S3. As we know, GO is compod of hydroxyl and aether groups on both sides and carboxyl ones on the edge. The bands at 1049 cm -1 and 1727 cm -1 are attributed to C–O in hydroxyl and C=O in carboxyl groups. The bands at 1224 cm -1 and 833 cm -1 are associated with symmetrical and asymmetrical stretching vibration of aether groups. However, no absorption bands obrved suggests that the function groups in the cleaned G are below the detection limit of FTIR.
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6. Raman
The Raman spectrums of Graphite, GO and cleaned G are shown in Fig. S4a. The Raman spectrum of GO is intervened by fluorescence. The Raman peaks of cleaned G are obtained by fitting (Fig. S4b). The peaks from left to right are signed as P1, P2, P3, P4 and P5. P2 and P5 are fixed as D band (1356cm -1) and G band (1580cm -1). P1 (1262cm -1) may be caud by C-N in graphene. P3 and P4 are possibly attributed to small domains of aromaticity and symmetry C=C respectively. The D/G ratio in Fig. S3
FTIR spectrum of cleaned G and GO.
intensity of G is 0.65 and it is lower than 0.78 of GO.
7. Film
The film deposited on ITO can be taken off from the substrate to become a freestanding film after it i
s dipped in 1 M HCl aqueous solution. Fig. S5 shows the photos of the graphene film on the ITO glass and the freestanding film. Scheme S1 is a diagram of the electrophoretic deposition process to prepare graphene films.
Fig. S4 Raman spectrums and analysis.
(a) Raman spectrums of graphite, GO and cleaned G ,销售招聘要求
(b) the fitting result of Raman of cleaned G
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Fig. S5
Photo of the graphene film on ITO and the freestanding film.
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Scheme S1 Diagram of electrophoretic deposition process.
