Ruimin Fu et.al.
Letter
SYNTHESIS AND CHARACTERIZATION OF STRUCTURE OF Fe3O4@GRAPHENE OXIDE NANOCOMPOSITES Ruimin Fu1, Mingfu Zhu2* Department of Life Science, Henan Institute of Education, Zhengzhou, Henan Province(450046),P. R. China 2 President of Hebi National Lighting Co.Ltd.,Hebi(458000),Henan Province, P.R.China
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*Author to whom correspondence should be addressed : E-mail:
[email protected] Received 2 November 2016; accepted 21 November 2016 ABSTRACT Nowadays, the hummers method for preparation of graphene oxide (GO) was improved. The grapheme oxide @ Fe3O4 magnetic nanocomposites were synthesized by co-precipitation method. After analysing the morphology and structure of obtained nanocomposites by X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared (FT-IR) spectroscopy, the result was shown as follows. The particle size of Fe3O4 in nanocomposites is 30 nm. Many functional groups are found in grapheme oxide, and such groups could be used to bind with the drug. In the test for magnetic properties, the nanocomposites gathered rapidly in the vicinity of the permanent magnet. The nanocomposites, with high superparamagnetism, can be used in the following applications: drug targeting transports, drug carrier, and diagnosis assistant system. Keywords: Graphene oxide; Fe3O4 magnetic nanocomposites; Characterization; magnetic properties
1. INTRODUCTION Nowadays, there are lots of research on graphene with good qualities, such as strongest mechanical strength, fast electron mobility rate, and specific surface [1-3]. Because of its unique structure, excellent performance, and low cost, graphene can be applied in electronic energy and biomedical material fields. However, graphene is hydrophobic, which inhibits its function in the water. To improve its dissolving property, graphene could be modified via oxidization into graphene oxide (GO) [4,5]. Many functional groups, for instance, carboxyl and hydroxyl groups, are present on the surface of hydrophilic GO, which can combine with other substance and can be used as a drug carrier [6–8]. To increase the targeting ability, graphene should be combined with some magnetic nanoparticles, such as Fe3O4 to form nanoparticle@graphene oxide (NGO) [9–12]. In a magnetic field, the NGO could migrate directly to the target position. Fe3O4, with the special magnetic properties and good biocompatibility, is considered to be an ideal candidate which used in the biological applications [1315] such as drug delivery, cell separation, and magneticresonance imaging [16-18]. Many methods have been used to prepare NGO. Yu has prepared NGO via the pyrolysis method [19-22]. Chen synthesized NGO by chemical crosslinking method[23]. However, the above-mentioned methods still have flaws such as uneven distribution of nanoparticle and poor specific magnetism; these flaws have limited the widespread application of NGO in different fields [24-28]. Based on the above-mentioned problem, an homogeneous Advanced Composites Letters, Vol. 25, Iss.6, 2016
precipitation method for preparing magnetic nanocomposites of Fe3O4 @grapheme which possess the advantages of strong magnetic properties has been developed and reported in this study. 2. EXPERIMENTAL SECTION 2.1 Materials All the chemical reagents which was used in this study were of analytical grade and were used without further purification. The crystal structure of NGO was examined by D8 Advanced X-ray diffractometer (XRD, Bruker company) and Raman spectrometer (Equinox 55 type, Bruker company). The interstructure and morphology of NGO were examined by transmission electron microscope (TEM, JEM1010 Japan). 2.2 GO Preparation GO was prepared from graphite powder by using the modified Hummer’s method. First, the graphites (2 g) was poured into a mixed solution of sodium nitrate (1 g) and concentrated H2SO4 (50 mL). The temperature was kept below 5 °C after stirring the mixture for 5 min, t. The potassium permanganate (7 g) was added into the bottle slowly. When the reaction was completed, it was treated with hydrogen peroxide (7 g). Stir and sonication lasted for 2 h, after which the mixture was heated to 40 °C and stirred for 24 h. Second, reaction system was cooled and transferred into an iced solution (400 mL) containing 30% H2O2 (3 mL), which was the graphene oxide gel. Third, the gel was stratified after 48 h of precipitation. The supernatant was discarded, and the remaining solid was washed in pure water thrice and was saved as the GO solution for further study. 143
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2.3 Synthesis of Fe3O4 nanoparticles According to hydrothermal synthesis method, the monodispersed Fe3O4 nanoparticles were prepared with minor modifications. In order to prepare monodispersed iron oxide, after dissolving FeCl3·6H2O (1 g) in ethylene glycol (40 mL) to form a clear solution, sodium acetate (3.6 g) and PEG (1 g) were added into the solution to form the mixture. After stirring mixture vigorously for 30 min at room temperature, it was sealed in a Teflon-lined stainlesssteel autoclave (50 mL capacity). After heating the autoclave to 200 °C and maintaining at this temperature for 8 h, it was cooled to room temperature. The black products were washed several times with ethanol and dried at 60 °C for 6 h. 2.4 Homogeneous synthesis of the Fe3O4@graphene nanoparticles The mixture was formed by adding 0.016g of monodispersed Fe3O4 nanoparticles into 1.139g GO solution with the concentration of 1mg/mL. After sonicating the mixture (1 g) for 20 min, it was heated to 90 °C and maintained at this temperature for 6 h under vigorous mechanical stirring. Ethanol and water were used to wash the solution several times. After drying at 60 °C overnight, the resultant precursor was separated with a magnet. After calcinating the residues for 2 h at 700 °C, Fe3O4@graphene nanocomposites were prepared. 3. RESULTS AND DISCUSSION 3.1 XRD analysis of nanocomposites The obtained products were analysed by using XRD to investigate the structure and composition of the nanocomposites. Results of XRD patterns of the Fe3O4 and Fe3O4@ graphene oxide nanoparticles(JCPDS No.65–3107) were shown in Fig 1. In Fig. 1a, we can see the magnetite material are indexed to the structure of Fe3O4 which have good crystallinity. In Fig. 1b which shows Fe3O4@graphene oxide, not only the characteristic diffraction peaks of cubic spinel Fe3O4 but also obvious diffraction peaks indexed to the cubic phase of grapheme were visible, thereby suggesting the successful crystallization of graphene oxide. Moreover, there was no peak in other phases in XRD results which indicated that no reaction occurred during the synthesis process.
Fig..1: XRD patterns of the samples: Fe3O4 (a) and Fe3O4@ graphene oxide (b). Advanced Composites Letters, Vol. 25, Iss.6, 2016
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3.2 TEM analysis of nanocomposites The samples were analysed by using TEM to investigate the morphology and size details of the nanocomposites and the results were shown in Fig. 2. From the TEM images, the magnetite consists of monodispersed particles with a mean particle size of 200 nm, with not closely compact structure, could be observed. The distribution size between the visible particles are narrow. The mean particle size of Fe3O4@graphene oxide nanoparticles was 250 nm and their non-aggregation and rough surface was maintained. The results suggest that GO nanoparticles deposits on the surface of Fe3O4.
Fig.2: TEM images of Fe3O4@graphene oxide
3.3 Magnetic properties of nanocomposites Using VSM and a SQUID magnetometer, the magnetic properties of the nanoparticles were investigated. The magnetic properties of Fe3O4 (a) and Fe3O4@graphene oxide(b) nanocomposites measured at 300 K were shown in Fig. 3. The saturation magnetization (Ms) value of Fe3O4 was 86.59 emu g-1. Nevertheless, the Ms value of the Fe3O4@GO nanocomposites was 11.5 emu g-1, which was much lower than that of Fe3O4 (86.59 emu g-1). It is probably because the percentage of Fe3O4 in the Fe3O4@GO is small. The nanocomposite with saturation magnetization was about 13.3%, which was very close to the theoretical concentration of the magnetite in nanocomposite(12.6% by mass). The inset graph in Fig. 3 illustrated the magnified hysteresis loops. The remanent magnetization (Mr) of the core-shell nanocomposites was 2.0 emu g-1. Meanwhile, the coercivity (Hc) of the core-shell nanocomposites was 160 Oe (at 300 K).These results further confirm the typical ferromagnetism of the nanoparticles. Moreover, the magnetization of Fe3O4@GO nanocomposites was sufficiently strong to permit bioseparation and magnetic resonance imaging. 3.4 FT-IR spectra of nanocomposites The chemical structures of Fe3O4 nanoparticle and graphene oxide were characterized. The oxygen-containing functional group of Fe3O4@graphene oxide were performed by FTIR. The result is shown in Fig. 4. Several 144
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characteristic peaks were identified in GO and Fe3O4@ graphene oxide. The absorbance peak nearby (434 cm-1) belongs to the stretching vibration of OH bands. The absorbance peak near the CH2 bands (2926 cm-1) belongs to stretching vibration of OH bands. The absorbance peak near CH2 bands (1632 cm-1) belongs to the stretching vibration of c=o bands. The absorbance peak near the C-O-C bands (1385 cm-1) belongs to the stretching vibration of OH bands. Results illustrated that when the graphite is oxidized, it will modify at least four functional groups, such as OH, COOH, C=O, and C-O-C. These polar groups contributed to the good hydrophilicity of GO. Moreover, compared with Fig. 4a, one stronger absorption peak was found at 580 cm-1, and this belongs to Fe-O-Fe stretching vibration, thereby illustrating that b in the Figure should be Fe3O4@graphene oxide nanocomposites with high purity.
Fig. 3: Magnetization curves of the Fe3O4 (a)and Fe3O4@ graphene oxide nanocomposites (b) at room temperature (300 K).
Fig.4: FTIR spectra of the graphene oxide (a)and Fe3O4@ graphene oxide nanocomposites (b) at room temperature (300 K).
Advanced Composites Letters, Vol. 25, Iss.6, 2016
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4. CONCLUSIONS In conclusion, an easy homogeneous precipitation method for magnetic Fe3O4@graphene nanocomposites was demonstrated in this study. The nanocomposites offer two distinct functionalities, which were shown as follows. Firstly, Fe3O4 gave strong magnetic properties to nanocomposites, which made them easy to manipulate and to observe by using various techniques, such as magnetic-resonance imaging. Secondly, graphene has a large specific surface area for carrying drugs [29]. Therefore, the magnetic Fe3O4@graphene nanocomposites have great potential for applications in drug carrier, drug targeting transports, and diagnosis assistant system. ACKNOWLEDGMENTS This work was kindly supported by the National Natural Science Foundation of China (No. 50372013). References: 1. Gu W, Deng X, Gu X, et al. Stabilized, superparamagnetic functionalized graphene/Fe3O4@Au nanocomposites for a magnetically-controlled solid-state electrochemiluminescence biosensing application[J]. Analytical chemistry, 2015, 87/3: 1876-1881. 2. Zhao L, Gao M, Yue W, et al. Sandwich-Structured Graphene-Fe3O4@ Carbon Nanocomposites for High-Performance Lithium-Ion Batteries[J]. ACS applied materials & interfaces, 2015, 7/18: 9709-9715. 3. Muthukrishnaraj A, Manokaran J, Vanitha M, et al. Equilibrium, kinetic and thermodynamic studies for the removal of Zn (II) and Ni (II) ions using magnetically recoverable graphene/Fe3O4 composite[J]. Desalination and Water Treatment, 2015, 56/9: 2485-2501. 4. Zhao G, Mo Z, Zhang P, et al. Synthesis of graphene/ Fe3O4/NiO magnetic nanocomposites and its application in photocatalytic degradation the organic pollutants in wastewater[J]. Journal of Porous Materials, 2015, 22/5: 1245-1253. 5. Lee J W, Kim J D. In Situ Chemical Synthesis of Fe3O4 Nanoparticles on Reduced Graphene Oxide Sheets in Polyol Medium and Magnetic Properties[J]. Journal of nanoscience and nanotechnology, 2015, 15/1: 215-219. 6. Zhou L, Peng X, Wang X, et al. Preparation and Characterization of Graphene/Fe3O4 Composites by Solvothermal Method[J]. Journal of nanoscience and nanotechnology, 2015, 15/6: 4380-4384. 7. Mehdinia A, Rouhani S, Mozaffari S. Microwave-assisted synthesis of reduced graphene oxide decorated with magnetite and gold nanoparticles, and its application to solid-phase extraction of organochlorine pesticides[J]. Microchimica Acta, 2016, 183/3: 1177-1185. 8. Wang L, Huang Y, Li C, et al. Hierarchical composites of polyaniline nanorod arrays covalently-grafted on the surfaces of graphene@ Fe3O4@C with high microwave absorption performance[J]. Composites Science and Technology, 2015, 108: 1-8. 9. He D X, Qiu Y, Li L L, et al. Large-scale solvent-thermal synthesis of graphene/magnetite/conductive oligomer ternary composites for microwave absorption[J]. Science China Materials, 2015, 58/7: 566-573. 10. Sharafeldin M, Bishop G W, Bhakta S, et al. Fe3O4 on 145
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