Qiuyun Ouyang, Hailong Yu, Zheng Xu, Yue Zhang, Chunyan Li,
Lihong Qi, and Yujin Chen
a) a) Authors to whom correspondence should be addressed. Electronic addresses: chenyujin@hrbeu.edu.cn
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Graphene sheets used in this work were purchased from Nanijng XFNano
Material Tech Co., Ltd, and their thickness and length are in the range of 0.8 nm and
0.5–2 μm, respectively.
1, 2
G/CdS nanocomposite was fabricated by a hydrothermal method. Simply, 3.0 mg of graphene was dispersed in 30 ml of ethanol/distilled water solution under ultrasonic conditions. Then 0.13 g of thioacetamide (CH
3
CSNH
2
) and
0.15 g of cadmium acetate ((CH
3
COO)
2
Cd∙H
2
O) were added, respectively. After sonication for 10 min, the mixture was transferred into a Teflon-lined stainless steel autoclave with a capacity of 50 ml for hydrothermal treatment at 180 o
C for 12 h. As the autoclave cooled to room temperature naturally, the precipitates were separated by centrifugation, washed with distilled water and absolute ethanol, and then dried for 24 h at 40 o
C under vacuum.
The G/CdS/PMMA organic glass was fabricated with the following steps.
Simply, 0.03 g of 2’2-azobis(isobutyronitrile) as an initiator was dispersed in 10.35 g of methyl methacrylate, then appropriate amount of G/CdS was added to the above solution. After sonication for 10 min and stirring for 40 min at room temperature, the mixture was heated to 75 o
C in a water bath under nitrogen atmosphere, and kept at the temperature for 30–35 min under stirring to obtain the jelly. The jelly was casted onto the cleaned glass mode. Then the glass mode was sealed well and dried at 45 o
C for 10 h. After cooling to room temperature naturally, the G/CdS/PMMA organic glass with thickness of 1 mm was obtained by ejecting. According to different amount
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of G/CdS, the obtained samples were denoted as (G/CdS)
3.9
/PMMA (3.9 mg),
(G/CdS)
7.8
/PMMA (7.8 mg) and (G/CdS)
11.7
/PMMA (11.7 mg), respectively. The
G/PMMA and CdS/PMMA organic glass as compared samples were also fabricated according to the above process.
Figure S1(a) shows X-ray diffraction (XRD) pattern of G/CdS nanocomposite.
The peaks indicated by Miller indices can be indexed to hexagonal CdS (JPCDs
41-1049). Due to poor crystallization of graphene, its broad diffraction peak located at
2
θ
of 22.5–27.5
o
, was not observed. Figure S1(b) shows a top-view scanning electron microscopy (SEM) image of the nanocomposite. It can be found that CdS nanoparticles are deposited on the surface of graphene uniformly. The side-view SEM image (the inset of Fig.
S1 (b) ) shows that the thickness of graphene is increased, implying that both sides of the graphene are coated with CdS nanoparticles. It should be noted that CdS nanoparticles are aggregated seriously if graphene sheets are not added in the reaction system, as shown in Fig. S 1(c) . Transmission electron microscopy (TEM) image of G/CdS nanocomposite displays that CdS nanoparticles have an average diameter of 25 nm, as shown in Fig. S1(d) . The inset in Fig.
S1(d) is a high-resolution TEM image of CdS nanoparticles. The clear lattice fringes were observed, indicating the single crystal nature of CdS nanoparticles. The spacing between two adjacent lattice planes is 0.336 nm, corresponding to (002) plane of CdS.
The results above demonstrate that G/CdS nanocomposite can be successfully obtained by the present method.
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FIG. S1. (a) XRD pattern of G/CdS nanocompostie, (b) a top-view SEM image of
G/CdS nanocompostie, and the inset shows its side-view SEM image, (c) SEM image of CdS obtained as graphene was not added in the reaction system, and (d) TEM image of G/CdS nanocompostie, and the inset shows HRTEM image of CdS nanoparticles deposited on the surface of graphene.
Figure S2 shows X-ray photoelectron spectroscopy (XPS) spectra of G/CdS nanocomposite and CdS nanoparticles. It can be clearly found that the binding energies of two Cd 3d and S 2p in G/CdS nanocomposite shift to higher energy and lower energy compared to CdS nanoparticles, respectively. It reveals that a charge transfer process occurs between CdS and graphene.
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FIG. S2.
XPS spectra of Cd 3d (a) and S 2p (b) of G/CdS nanocomposite, and XPS spectra of Cd 3d (c) and S 2p (d) of CdS nanoparticles.
References
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Y. J. Chen, Q. S. Wang, C. L. Zhu, P. Gao, Q. Y. Ouyang, T. S. Wang, Y. Ma, and C.
W. Sun, J. Mater. Chem.
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W. Sun, and M. S. Cao, J. Mater. Chem.
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