- Email: [email protected]
reduced graphene oxide nanocomposites with enhanced absorption and photocatalytic performance
Materials Letters 126 (2014) 220–223
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Sonochemical synthesis of CuS/reduced graphene oxide nanocomposites with enhanced absorption and photocatalytic performance Jingjing Shi, Xiaoyan Zhou, Ya Liu, Qingmei Su, Jun Zhang, Gaohui Du n Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
art ic l e i nf o
a b s t r a c t
Article history: Received 24 February 2014 Accepted 8 April 2014 Available online 16 April 2014
The CuS nanoparticle-decorated reduced graphene oxide (CuS/rGO) composites have been successfully prepared via a sonochemical method. X-ray diffraction and electron microscopy observations confirm that CuS nanoparticles of 10–25 nm are well distributed on the rGO nanosheets. Ultraviolet–visible spectroscopy reveals the CuS/rGO nonocomposites show a strong and broad light absorption. Photocatalytic performance of the CuS/rGO nanocomposites is evaluated by measuring the decomposition of methylene blue solution under natural light. The experimental results reveal that the as-prepared nanocomposites show remarkably enhanced photocatalytic activity compared with pure CuS. This can be attributed to the enhanced light adsorption, strong dyestuff absorption, and efficient charge transport after the introduction of rGO. & 2014 Elsevier B.V. All rights reserved.
Keywords: Nanocomposites Sonochemistry Electron microscopy Photocatalysis
1. Introduction In recent years, the environmental problems are becoming increasingly conspicuous, especially the organic dye pollution. Solar energy is an inexhaustible, low cost, and environmentally friendly energy resource [1]. As a result, numerous studies have been conducted on photocatalytic strategy for the removal of contamination [2]. Reduced graphene oxide (rGO) nanosheets have aroused tremendous interest as the support for anchoring nanoparticles due to the high surface area, excellent conductivity and superior electron mobility [3]. To date, various kinds of materials with different morphologies and sizes, including metals, metal oxides, metal sulfides and polymers have been integrated with rGO [4–6]. These hybrid materials show remarkably enhanced performances in catalysis, photoelectrochemistry and electrochemistry as compared with each individual component owing to the increased efficient electron transfer and active surface sites provided by rGO [7,8]. Up to now, some of the chalcogenide nanomaterials, such as SnS2, CdS, ZnS and CuS, have been successfully grafted on rGO [4,9]. As a p-type semiconductor metal chalcogenide, copper sulfides (CuS) have drawn great attention owing to their interesting optical and electrical properties, especially their photocatalytic properties [10,11].
n
Corresponding author. Tel: þ 86 579 82283897; fax: þ 86 579 82282595. E-mail address: [email protected] (G. Du).
http://dx.doi.org/10.1016/j.matlet.2014.04.051 0167-577X/& 2014 Elsevier B.V. All rights reserved.
The reported techniques to prepare CuS/rGO nanocomposites include mainly hydrothermal method or solvothermal method. For example, Zhang et al. reported the preparation of CuS/rGO using a hydrothermal method [12]. Nie et al. reported a one-pot hydrothermal synthesis of CuS/rGO with enhanced peroxidase-like catalytic activity [4]. Zhao et al. successfully prepared a CuS/rGO via a solvothermal route [10]. The development of new routes for fabrication of CuS/rGO composites is still highly desired. Here, we report a one-step sonochemical method for the synthesis of CuS/ rGO for the first time, which is a facile route operated under ambient conditions with the advantages of low cost and simplicity. In particular, the obtained CuS/rGO shows excellent photocatalytic performance.
2. Experiment Graphene oxide (GO) was synthesized from graphite powers by a modified hummers method [13]. The as-prepared GO was then heated at 200 1C in air for 10 min. CuS/rGO composites were prepared in the following procedures. Different amount of the obtained GO and 5 mmol of CuCl2 2H2O were ultrasonically dispersed in 200 mL ethylene glycol (EG); 5 mmol of thioacetamide (TAA) was then added to the solution under ultrasound irradiation (45 kHz and 60 W) at room temperature. After the solution showed an obvious color change from grey to deep black, the ultrasound irradiation continued for additional 30 min.
J. Shi et al. / Materials Letters 126 (2014) 220–223
Subsequently, the black precipitates were centrifuged, washed with distilled water and absolute ethanol, and dried at 60 1C. Products prepared with different amount of GO (0, 0.05, 0.1 and 0.15 g) were marked as pure CuS, S1, S2, and S3. The products were characterized by XRD, SEM, TEM, FT-IR and UV–vis absorption. The photodegradation of methylene blue (MB) was used to investigate the photocatalytic properties of CuS/rGO with the assistance of hydrogen peroxide [11,14].
3. Results and discussion Our strategy for the sonochemical preparation of CuS/rGO composites is illustrated in Fig. 1. It is well known that many oxygen-containing functional groups such as hydroxyl, carboxyl and epoxy groups are attached on the basal plane of GO nanosheets. The defect sites together with the negatively charged surface are of great benefit to bind with cations [15]. With the addition of CuCl2 2H2O into GO suspension under ultrasonication, Cu2 þ was uniformly and tightly anchored on the surface of GO nanosheets via the electrostatic interaction. When the TAA is added, H2S can be released under continuous ultrasonic irradiation, which acts as a sulfide source to form CuS nanoparticles. TAA and EG are also work as reducing agents to effectively reduce GO to rGO [16,17]. As a result, CuS/rGO nanocomposites are produced. The XRD patterns of the as-prepared pure CuS and CuS/rGO (S2) composites are shown in Fig. 2(a). All the diffraction peaks of the pure CuS agree well with the hexagonal phase of CuS (JCPDS No. 06-0464). The characteristic peaks of hexagonal CuS are also observed for CuS/rGO composites. Besides, the (0 0 2) diffraction peak of rGO located at about 241 in the XRD pattern is found but not obvious because the diffraction of disorderedly stacked rGO nanosheets is much weaker as compared to the well-crystalline CuS. To further confirm the reduction of GO, FT-IR spectra were recorded as depicted in Fig. 2(b). The characteristic bands of GO are observed at 1049 cm 1 (alkoxy C–O stretching), 1398 cm 1 (carboxyl C–O stretching), 1625 cm 1 (H–O–H bending band), 1718 cm 1 (C ¼O stretching vibrations). Compared with the peaks
221
of GO, CuS/rGO has a similar spectrum but with much lower absorption intensity at 1718, 1625, 1398 and 1049 cm 1, which indicates that the oxygen-containing functional groups are partially removed. In other words, the GO has been reduced by TAA and EG during the preparation [18]. Fig. 3(a) shows a SEM image of pure CuS, which is composed of severely agglomerated particles with large size. Contrarily, CuS/ rGO (S2) composites show different morphology (Fig. 3(b)); the rGO nanosheets have been densely decorated with a large amount of small nanoparticles. The microstructure was further examined using TEM. It can be seen in Fig. 3(c) that the CuS nanoparticles are relatively well distributed on rGO sheets, and the sizes of CuS nanoparticles are around 10–25 nm. Fig. 3(d) presents a HRTEM image and FFT pattern of a CuS nanoparticle. The lattice spacing between two adjacent lattice fringes is 0.286 nm and 0.339 nm, corresponding to the interspaces of the (1 0 3) and ( 1 1 0) planes of hexagonal CuS. The HRTEM and FFT pattern reveal that each nanoparticle is single-crystalline. These results reveal that the addition of GO sheets can prevent CuS nanoparticles from aggregating in the synthesis process. Fig. 4(a) displays the UV–vis absorption spectra of CuS/rGO (S2) composites and pure CuS particles. Obviously, the addition of rGO induces the increased light absorption in both the UV and visible light regions compared to pure CuS. The strong absorption of the composites in the visible range implicates the potential application of the nanocomposites in photocurrent generation and photocatalysis. N2 adsorption–desorption isotherms of rGO and CuS/rGO (S2) were measured as shown in Fig. 4(b). It is calculated that the specific surface area of CuS/rGO is 993.5 m2/g, which is much larger than pure rGO (373.7 m2/g). The higher surface area is conducive to the increase of surface active sites and the transport of charge carriers, and is of benefit to the improvement of the adsorption and photocatalytic activity. MB is chosen as a representative organic dyestuff to evaluate the photocatalytic performance of CuS/rGO. The degradation ratio is calculated by C/Co, where Co is the initial concentration and C is the concentration of remaining MB at different time. Fig. 4 (c) shows the degradation curves of a 50 ppm MB aqueous
Fig. 1. Schematic illustration of the sonication route to CuS/rGO.
Fig. 2. (a) XRD patterns of pure CuS and CuS/rGO composite. (b) FTIR spectra of GO and CuS/rGO.
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J. Shi et al. / Materials Letters 126 (2014) 220–223
Fig. 3. SEM images of pure CuS (a) and CuS/rGO composites (b). TEM images (c) and HRTEM image (d) of CuS/rGO. The inset of (d) is the corresponding FFT pattern.
Fig. 4. (a) UV–vis absorption of CuS and CuS/rGO composites. (b) Nitrogen adsorption–desorption isotherms of rGO and CuS/rGO. (c) Photodegradation behaviors of MB with rGO, CuS, and CuS/rGO composites.
solution with CuS/rGO. For comparison, the photocatalytic performances of pure CuS and rGO were also evaluated. In the beginning of the experiments, the MB solutions with 50 mg of samples were aged in the dark for 20 min under stirring to examine their adsorption abilities. We can observe that the CuS/rGO (S1, S2 and S3) composites show higher adsorption ability to MB than pure CuS particles and rGO sheets. A typical phenomenon for the rGO preparation is the re-stacking of rGO sheets during the reduction and drying processes, which leads to changes in intrinsic chemical and physical properties (e.g. the specific surface area). This can be proved by Fig. 4(b) that the surface area of CuS/rGO composites is much larger than the pure rGO. In our synthesis, the CuS nanoparticles are grown in situ on the rGO surface and can prevent effectively the rGO sheets from re-stacking. Furthermore, the degradation rate of MB with CuS/rGO composites is much higher than that of pure CuS and rGO. The improved photocatalytic activity can be attributed to several aspects. First, CuS/rGO has intensive light absorption, which can promote the excitation of electrons from the valence band to the conduction band, and thus the formation of photogenerated electrons and holes in CuS. Secondly, the enhanced adsorption of CuS/rGO nanocomposites to MB can provide a high concentration of MB near to the CuS nanoparticles on rGO, leading to highly efficient contact between
them, which can speed up the reaction between the photogenerated active species and the MB molecules. It is worth noting that S2 sample (containing 20% rGO) possesses the most outstanding photocatalitic activity, that's to say, better than S1 (containing 10% rGO) and S3 (containing 30% rGO), which may be resulted from the favorable dispersibility and the maximum synergistic interaction between rGO and CuS nanoparticles.
4. Conclusion In summary, CuS/rGO composites have been successfully prepared via a sonochemical method. XRD, SEM and TEM analyses reveal that the CuS particles with diameters of 10–25 nm are well dispersed on the surface of rGO nanosheets. The photocatalytic experiment indicates that CuS/rGO nanocomposites exhibit an enhanced photocatalytic performance compared with pure CuS or rGO, which can be attributed to the enhanced light adsorption, strong dyestuff absorption, and efficient charge transport after the introduction of rGO. The advantages of our method for the synthesis of CuS/rGO nanocomposites lie in the room temperature and mild reaction conditions, which permit large-scale production at low cost.
J. Shi et al. / Materials Letters 126 (2014) 220–223
References [1] Xie D, Chang L, Wang FX, Du GH, Xu BS. J Alloy Compd 2012;545:176–81. [2] Rauf MA, Ashraf SS. Chem Eng J 2009;151:10–8. [3] Meyer JC, Geim AK, Katsnelson MI, Novoselov KS, Booth TJ, Roth S. Nature 2007;446:60–3. [4] Nie GD, Zhang L, Lu XF, Bian XJ, Sun WN, Wang C. Dalton Trans 2013;42: 14006–13. [5] Chi XN, Chang L, Xie D, Zhang J, Du GH. Mater Lett 2013;106:178–81. [6] Xu C, Wang X, Zhu JW. J Phys Chem C 2008;112:19841–5. [7] Yoo E, Okata T, Akita T, Kohyama M, Nakamura J, Honma I. Nano Lett 2009;9:2255–9. [8] Zhou GM, Wang DW, Li F, Zhang LL, Li N, Wu ZS, et al. Chem Mater 2010;22:5306–13.
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[9] Liu FZ, Shao X, Li HY, Wang M, Yang SR. Mater Lett 2013;108:125–8. [10] Zhao XJ, Zhang FY, Lu DB, Du YL, Ye WC, Wang CM. Anal Methods 2013;5:3992–8. [11] Li F, Wu JF, Qin QH, Li Z, Huang XT. Powder Technol 2010;198:267–74. [12] Zhang YW, Tian JQ, Li HY, Wang L, Qin XY, Asiri AM, et al. Langmuir 2012;28:12893–900. [13] Hummers WS, Offeman RE. J Am Chem Soc 1958;80:1339 (9). [14] Ding TY, Wang MS, Guo SP, Guo GC, Huang JS. Mater Lett 2008;62:4529–31. [15] Ye TF, Su JM, Cheng C, Chang TH, Teng H. Adv Funct Mater 2010;20:2255–62. [16] Zeng B, Chen XH, Chen CS, Ning XT, Deng WN. J Alloy Compd 2014;582:774–9. [17] Chang K, Chen WX. ACS Nano 2011;5:4720–8. [18] Li BJ, Cao HQ, Yin G, Lu YX, Yin JF. J Mater Chem 2011;21:10645–8.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Sonochemical synthesis of CuS/reduced graphene oxide nanocomposites with enhanced absorption and photocatalytic performance Jingjing Shi, Xiaoyan Zhou, Ya Liu, Qingmei Su, Jun Zhang, Gaohui Du n Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
art ic l e i nf o
a b s t r a c t
Article history: Received 24 February 2014 Accepted 8 April 2014 Available online 16 April 2014
The CuS nanoparticle-decorated reduced graphene oxide (CuS/rGO) composites have been successfully prepared via a sonochemical method. X-ray diffraction and electron microscopy observations confirm that CuS nanoparticles of 10–25 nm are well distributed on the rGO nanosheets. Ultraviolet–visible spectroscopy reveals the CuS/rGO nonocomposites show a strong and broad light absorption. Photocatalytic performance of the CuS/rGO nanocomposites is evaluated by measuring the decomposition of methylene blue solution under natural light. The experimental results reveal that the as-prepared nanocomposites show remarkably enhanced photocatalytic activity compared with pure CuS. This can be attributed to the enhanced light adsorption, strong dyestuff absorption, and efficient charge transport after the introduction of rGO. & 2014 Elsevier B.V. All rights reserved.
Keywords: Nanocomposites Sonochemistry Electron microscopy Photocatalysis
1. Introduction In recent years, the environmental problems are becoming increasingly conspicuous, especially the organic dye pollution. Solar energy is an inexhaustible, low cost, and environmentally friendly energy resource [1]. As a result, numerous studies have been conducted on photocatalytic strategy for the removal of contamination [2]. Reduced graphene oxide (rGO) nanosheets have aroused tremendous interest as the support for anchoring nanoparticles due to the high surface area, excellent conductivity and superior electron mobility [3]. To date, various kinds of materials with different morphologies and sizes, including metals, metal oxides, metal sulfides and polymers have been integrated with rGO [4–6]. These hybrid materials show remarkably enhanced performances in catalysis, photoelectrochemistry and electrochemistry as compared with each individual component owing to the increased efficient electron transfer and active surface sites provided by rGO [7,8]. Up to now, some of the chalcogenide nanomaterials, such as SnS2, CdS, ZnS and CuS, have been successfully grafted on rGO [4,9]. As a p-type semiconductor metal chalcogenide, copper sulfides (CuS) have drawn great attention owing to their interesting optical and electrical properties, especially their photocatalytic properties [10,11].
n
Corresponding author. Tel: þ 86 579 82283897; fax: þ 86 579 82282595. E-mail address: [email protected] (G. Du).
http://dx.doi.org/10.1016/j.matlet.2014.04.051 0167-577X/& 2014 Elsevier B.V. All rights reserved.
The reported techniques to prepare CuS/rGO nanocomposites include mainly hydrothermal method or solvothermal method. For example, Zhang et al. reported the preparation of CuS/rGO using a hydrothermal method [12]. Nie et al. reported a one-pot hydrothermal synthesis of CuS/rGO with enhanced peroxidase-like catalytic activity [4]. Zhao et al. successfully prepared a CuS/rGO via a solvothermal route [10]. The development of new routes for fabrication of CuS/rGO composites is still highly desired. Here, we report a one-step sonochemical method for the synthesis of CuS/ rGO for the first time, which is a facile route operated under ambient conditions with the advantages of low cost and simplicity. In particular, the obtained CuS/rGO shows excellent photocatalytic performance.
2. Experiment Graphene oxide (GO) was synthesized from graphite powers by a modified hummers method [13]. The as-prepared GO was then heated at 200 1C in air for 10 min. CuS/rGO composites were prepared in the following procedures. Different amount of the obtained GO and 5 mmol of CuCl2 2H2O were ultrasonically dispersed in 200 mL ethylene glycol (EG); 5 mmol of thioacetamide (TAA) was then added to the solution under ultrasound irradiation (45 kHz and 60 W) at room temperature. After the solution showed an obvious color change from grey to deep black, the ultrasound irradiation continued for additional 30 min.
J. Shi et al. / Materials Letters 126 (2014) 220–223
Subsequently, the black precipitates were centrifuged, washed with distilled water and absolute ethanol, and dried at 60 1C. Products prepared with different amount of GO (0, 0.05, 0.1 and 0.15 g) were marked as pure CuS, S1, S2, and S3. The products were characterized by XRD, SEM, TEM, FT-IR and UV–vis absorption. The photodegradation of methylene blue (MB) was used to investigate the photocatalytic properties of CuS/rGO with the assistance of hydrogen peroxide [11,14].
3. Results and discussion Our strategy for the sonochemical preparation of CuS/rGO composites is illustrated in Fig. 1. It is well known that many oxygen-containing functional groups such as hydroxyl, carboxyl and epoxy groups are attached on the basal plane of GO nanosheets. The defect sites together with the negatively charged surface are of great benefit to bind with cations [15]. With the addition of CuCl2 2H2O into GO suspension under ultrasonication, Cu2 þ was uniformly and tightly anchored on the surface of GO nanosheets via the electrostatic interaction. When the TAA is added, H2S can be released under continuous ultrasonic irradiation, which acts as a sulfide source to form CuS nanoparticles. TAA and EG are also work as reducing agents to effectively reduce GO to rGO [16,17]. As a result, CuS/rGO nanocomposites are produced. The XRD patterns of the as-prepared pure CuS and CuS/rGO (S2) composites are shown in Fig. 2(a). All the diffraction peaks of the pure CuS agree well with the hexagonal phase of CuS (JCPDS No. 06-0464). The characteristic peaks of hexagonal CuS are also observed for CuS/rGO composites. Besides, the (0 0 2) diffraction peak of rGO located at about 241 in the XRD pattern is found but not obvious because the diffraction of disorderedly stacked rGO nanosheets is much weaker as compared to the well-crystalline CuS. To further confirm the reduction of GO, FT-IR spectra were recorded as depicted in Fig. 2(b). The characteristic bands of GO are observed at 1049 cm 1 (alkoxy C–O stretching), 1398 cm 1 (carboxyl C–O stretching), 1625 cm 1 (H–O–H bending band), 1718 cm 1 (C ¼O stretching vibrations). Compared with the peaks
221
of GO, CuS/rGO has a similar spectrum but with much lower absorption intensity at 1718, 1625, 1398 and 1049 cm 1, which indicates that the oxygen-containing functional groups are partially removed. In other words, the GO has been reduced by TAA and EG during the preparation [18]. Fig. 3(a) shows a SEM image of pure CuS, which is composed of severely agglomerated particles with large size. Contrarily, CuS/ rGO (S2) composites show different morphology (Fig. 3(b)); the rGO nanosheets have been densely decorated with a large amount of small nanoparticles. The microstructure was further examined using TEM. It can be seen in Fig. 3(c) that the CuS nanoparticles are relatively well distributed on rGO sheets, and the sizes of CuS nanoparticles are around 10–25 nm. Fig. 3(d) presents a HRTEM image and FFT pattern of a CuS nanoparticle. The lattice spacing between two adjacent lattice fringes is 0.286 nm and 0.339 nm, corresponding to the interspaces of the (1 0 3) and ( 1 1 0) planes of hexagonal CuS. The HRTEM and FFT pattern reveal that each nanoparticle is single-crystalline. These results reveal that the addition of GO sheets can prevent CuS nanoparticles from aggregating in the synthesis process. Fig. 4(a) displays the UV–vis absorption spectra of CuS/rGO (S2) composites and pure CuS particles. Obviously, the addition of rGO induces the increased light absorption in both the UV and visible light regions compared to pure CuS. The strong absorption of the composites in the visible range implicates the potential application of the nanocomposites in photocurrent generation and photocatalysis. N2 adsorption–desorption isotherms of rGO and CuS/rGO (S2) were measured as shown in Fig. 4(b). It is calculated that the specific surface area of CuS/rGO is 993.5 m2/g, which is much larger than pure rGO (373.7 m2/g). The higher surface area is conducive to the increase of surface active sites and the transport of charge carriers, and is of benefit to the improvement of the adsorption and photocatalytic activity. MB is chosen as a representative organic dyestuff to evaluate the photocatalytic performance of CuS/rGO. The degradation ratio is calculated by C/Co, where Co is the initial concentration and C is the concentration of remaining MB at different time. Fig. 4 (c) shows the degradation curves of a 50 ppm MB aqueous
Fig. 1. Schematic illustration of the sonication route to CuS/rGO.
Fig. 2. (a) XRD patterns of pure CuS and CuS/rGO composite. (b) FTIR spectra of GO and CuS/rGO.
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J. Shi et al. / Materials Letters 126 (2014) 220–223
Fig. 3. SEM images of pure CuS (a) and CuS/rGO composites (b). TEM images (c) and HRTEM image (d) of CuS/rGO. The inset of (d) is the corresponding FFT pattern.
Fig. 4. (a) UV–vis absorption of CuS and CuS/rGO composites. (b) Nitrogen adsorption–desorption isotherms of rGO and CuS/rGO. (c) Photodegradation behaviors of MB with rGO, CuS, and CuS/rGO composites.
solution with CuS/rGO. For comparison, the photocatalytic performances of pure CuS and rGO were also evaluated. In the beginning of the experiments, the MB solutions with 50 mg of samples were aged in the dark for 20 min under stirring to examine their adsorption abilities. We can observe that the CuS/rGO (S1, S2 and S3) composites show higher adsorption ability to MB than pure CuS particles and rGO sheets. A typical phenomenon for the rGO preparation is the re-stacking of rGO sheets during the reduction and drying processes, which leads to changes in intrinsic chemical and physical properties (e.g. the specific surface area). This can be proved by Fig. 4(b) that the surface area of CuS/rGO composites is much larger than the pure rGO. In our synthesis, the CuS nanoparticles are grown in situ on the rGO surface and can prevent effectively the rGO sheets from re-stacking. Furthermore, the degradation rate of MB with CuS/rGO composites is much higher than that of pure CuS and rGO. The improved photocatalytic activity can be attributed to several aspects. First, CuS/rGO has intensive light absorption, which can promote the excitation of electrons from the valence band to the conduction band, and thus the formation of photogenerated electrons and holes in CuS. Secondly, the enhanced adsorption of CuS/rGO nanocomposites to MB can provide a high concentration of MB near to the CuS nanoparticles on rGO, leading to highly efficient contact between
them, which can speed up the reaction between the photogenerated active species and the MB molecules. It is worth noting that S2 sample (containing 20% rGO) possesses the most outstanding photocatalitic activity, that's to say, better than S1 (containing 10% rGO) and S3 (containing 30% rGO), which may be resulted from the favorable dispersibility and the maximum synergistic interaction between rGO and CuS nanoparticles.
4. Conclusion In summary, CuS/rGO composites have been successfully prepared via a sonochemical method. XRD, SEM and TEM analyses reveal that the CuS particles with diameters of 10–25 nm are well dispersed on the surface of rGO nanosheets. The photocatalytic experiment indicates that CuS/rGO nanocomposites exhibit an enhanced photocatalytic performance compared with pure CuS or rGO, which can be attributed to the enhanced light adsorption, strong dyestuff absorption, and efficient charge transport after the introduction of rGO. The advantages of our method for the synthesis of CuS/rGO nanocomposites lie in the room temperature and mild reaction conditions, which permit large-scale production at low cost.
J. Shi et al. / Materials Letters 126 (2014) 220–223
References [1] Xie D, Chang L, Wang FX, Du GH, Xu BS. J Alloy Compd 2012;545:176–81. [2] Rauf MA, Ashraf SS. Chem Eng J 2009;151:10–8. [3] Meyer JC, Geim AK, Katsnelson MI, Novoselov KS, Booth TJ, Roth S. Nature 2007;446:60–3. [4] Nie GD, Zhang L, Lu XF, Bian XJ, Sun WN, Wang C. Dalton Trans 2013;42: 14006–13. [5] Chi XN, Chang L, Xie D, Zhang J, Du GH. Mater Lett 2013;106:178–81. [6] Xu C, Wang X, Zhu JW. J Phys Chem C 2008;112:19841–5. [7] Yoo E, Okata T, Akita T, Kohyama M, Nakamura J, Honma I. Nano Lett 2009;9:2255–9. [8] Zhou GM, Wang DW, Li F, Zhang LL, Li N, Wu ZS, et al. Chem Mater 2010;22:5306–13.
223
[9] Liu FZ, Shao X, Li HY, Wang M, Yang SR. Mater Lett 2013;108:125–8. [10] Zhao XJ, Zhang FY, Lu DB, Du YL, Ye WC, Wang CM. Anal Methods 2013;5:3992–8. [11] Li F, Wu JF, Qin QH, Li Z, Huang XT. Powder Technol 2010;198:267–74. [12] Zhang YW, Tian JQ, Li HY, Wang L, Qin XY, Asiri AM, et al. Langmuir 2012;28:12893–900. [13] Hummers WS, Offeman RE. J Am Chem Soc 1958;80:1339 (9). [14] Ding TY, Wang MS, Guo SP, Guo GC, Huang JS. Mater Lett 2008;62:4529–31. [15] Ye TF, Su JM, Cheng C, Chang TH, Teng H. Adv Funct Mater 2010;20:2255–62. [16] Zeng B, Chen XH, Chen CS, Ning XT, Deng WN. J Alloy Compd 2014;582:774–9. [17] Chang K, Chen WX. ACS Nano 2011;5:4720–8. [18] Li BJ, Cao HQ, Yin G, Lu YX, Yin JF. J Mater Chem 2011;21:10645–8.