The present investigation reports new results on optical properties of graphene-metal nanocomposites. These composites were prepared by a solution-based chemical approach. Graphene has been prepared by thermal reduction of graphene oxide (GO) at 90°C by hydrazine hydrate in an ammoniacal medium. This ammoniacal solution acts as a solvent as well as a basic medium where agglomeration of graphene can be prevented. This graphene solution has further been used for functionalization with Ag, Au, and Cu nanoparticles (NPs). The samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-Vis spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to reveal the nature and type of interaction of metal nanoparticles with graphene. The results indicate distinct shift of graphene bands both in Raman and UV-Vis spectroscopies due to the presence of the metal nanoparticles. Raman spectroscopic analysis indicates blue shift of D and G bands in Raman spectra of graphene due to the presence of metal nanoparticles except for the G band of Cu-G, which undergoes red shift, reflecting the charge transfer interaction between graphene sheets and metal nanoparticles. UV-Vis spectroscopic analysis also indicates blue shift of graphene absorption peak in the hybrids. The plasmon peak position undergoes blue shift in Ag-G, whereas red shift is observed in Au-G and Cu-G. 1. Introduction Graphene is a unique allotrope of carbon characterized by honeycomb lattice of sp2-hybridized carbon atoms in which carbon atoms are packed in a two-dimensional (2D) hexagonal lattice [1]. Graphene, often considered as a “miracle material” of the 21st century, has attracted tremendous attention in the academic community [2]. Being one-atomic layer thick sheet of carbon extending infinitely in 2D, its properties encompass range of superlattices. This includes high value of Young’s modulus (~1100？GPa) [3], fracture strength (125？GPa) [3], thermal conductivity (~5000？W/mK) [4], mobility of charge carriers ( ？cm2/Vs) [5], and specific surface area 2630？(m2/g) [6]. Owing to its excellent physical and chemical properties, graphene is considered as a potential candidate for large number of applications in many technological fields such as nanoelectronics [7], composites [8], energy storage devices [6], efficient lasers, photodetectors, and biomedical applications [9]. Preparation of high quality graphene is needed to study the unique properties for applications. A number of different ways of preparing graphene have been reported in the literature
References
[1]
A. K. Geim and K. S. Novoselov, “The rise of graphene,” Nature Materials, vol. 6, no. 3, pp. 183–191, 2007.
[2]
X. Huang, Z. Yin, S. Wu et al., “Graphene-based materials: synthesis, characterization, properties, and applications,” Small, vol. 7, no. 14, pp. 1876–1902, 2011.
[3]
C. Lee, X. Wei, J. W. Kysar, and J. Hone, “Measurement of the elastic properties and intrinsic strength of monolayer graphene,” Science, vol. 321, no. 5887, pp. 385–388, 2008.
[4]
A. A. Balandin, S. Ghosh, W. Bao et al., “Superior thermal conductivity of single-layer graphene,” Nano Letters, vol. 8, no. 3, pp. 902–907, 2008.
[5]
K. I. Bolotin, K. J. Sikes, Z. Jiang et al., “Ultrahigh electron mobility in suspended graphene,” Solid State Communications, vol. 146, no. 9-10, pp. 351–355, 2008.
[6]
M. D. Stoller, S. Park, Z. Yanwu, J. An, and R. S. Ruoff, “Graphene-based ultracapacitors,” Nano Letters, vol. 8, no. 10, pp. 3498–3502, 2008.
[7]
D. A. Areshkin and C. T. White, “Building blocks for integrated graphene circuits,” Nano Letters, vol. 7, no. 11, pp. 3253–3259, 2007.
[8]
U. Khan, P. May, A. O'Neill, and J. N. Coleman, “Development of stiff, strong, yet tough composites by the addition of solvent exfoliated graphene to polyurethane,” Carbon, vol. 48, no. 14, pp. 4035–4041, 2010.
[9]
J. Y. Liu and R. H. Hurt, “Ion release kinetics and particle persistence in aqueous nano-silver colloids,” Environmental Science and Technology, vol. 44, no. 6, pp. 2169–2175, 2010.
[10]
M. Pumera, “Graphene-based nanomaterials and their electrochemistry,” Chemical Society Reviews, vol. 39, no. 11, pp. 4146–4157, 2010.
[11]
X. Lu, M. Yu, H. Huang, and R. S. Ruoff, “Tailoring graphite with the goal of achieving single sheets,” Nanotechnology, vol. 10, no. 3, pp. 269–272, 1999.
[12]
M. Eizenberg and J. M. Blakely, “Carbon monolayer phase condensation on Ni(111),” Surface Science, vol. 82, no. 1, pp. 228–236, 1979.
[13]
S. Stankovich, D. A. Dikin, R. D. Piner et al., “Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide,” Carbon, vol. 45, no. 7, pp. 1558–1565, 2007.
[14]
S. Niyogi, E. Bekyarova, M. E. Itkis, J. L. McWilliams, M. A. Hamon, and R. C. Haddon, “Solution properties of graphite and graphene,” Journal of the American Chemical Society, vol. 128, no. 24, pp. 7720–7721, 2006.
[15]
L.-X. Li, B.-G. An, H. Nishihara et al., “Water-dispersible “carbon nanopods” with controllable graphene layer orientation,” Chemical Communications, no. 30, pp. 4554–4556, 2009.
[16]
Y.-K. Kim, H.-K. Na, and D.-H. Min, “Influence of surface functionalization on the growth of gold nanostructures on graphene thin films,” Langmuir, vol. 26, no. 16, pp. 13065–13070, 2010.
[17]
K. Jasuja and V. Berry, “Implantation and growth of dendritic gold nanostructures on graphene derivatives: electrical property tailoring and Raman enhancement,” ACS Nano, vol. 3, no. 8, pp. 2358–2366, 2009.
[18]
J. Li and C.-Y. Liu, “Ag/Graphene heterostructures: synthesis, characterization and optical properties,” European Journal of Inorganic Chemistry, no. 8, pp. 1244–1248, 2010.
[19]
N. Tian, Z.-Y. Zhou, S.-G. Sun, Y. Ding, and L. W. Zhong, “Synthesis of tetrahexahedral platinum nanocrystals with high-index facets and high electro-oxidation activity,” Science, vol. 316, no. 5825, pp. 732–735, 2007.
[20]
B. Lim, M. Jiang, P. H. C. Camargo et al., “Pd-Pt bimetallic nanodendrites with high activity for oxygen reduction,” Science, vol. 324, no. 5932, pp. 1302–1305, 2009.
[21]
S. Chu, L. Hu, X. Hu, M. Yang, and J. Deng, “Titanium-embedded graphene as high-capacity hydrogen-storage media,” International Journal of Hydrogen Energy, vol. 36, no. 19, pp. 12324–12328, 2011.
[22]
D. Astruc, F. Lu, and J. R. Aranzaes, “Nanoparticles as recyclable catalysts: the frontier between homogeneous and heterogeneous catalysis,” Angewandte Chemie—International Edition, vol. 44, no. 48, pp. 7852–7872, 2005.
[23]
A. Y. Stakheev and L. M. Kustov, “Effects of the support on the morphology and electronic properties of supported metal clusters: modern concepts and progress in 1990s,” Applied Catalysis A, vol. 188, no. 1-2, pp. 3–35, 1999.
[24]
W. Yuana, Y. Gua, and L. Li, “Green synthesis of graphene/Ag nanocomposites,” Applied Surface Science, vol. 261, pp. 753–758, 2012.
[25]
K. S. Subrahmanyam, A. K. Manna, S. K. Pati, and C. N. R. Rao, “A study of graphene decorated with metal nanoparticles,” Chemical Physics Letters, vol. 497, no. 1–3, pp. 70–75, 2010.
[26]
W. S. Hummers Jr. and R. E. Offeman, “Preparation of graphitic oxide,” Journal of the American Chemical Society, vol. 80, no. 6, p. 1339, 1958.
[27]
A. Mao, D. Zhang, X. Jin et al., “Synthesis of graphene oxide sheets decorated by silver nanoparticles in organic phase and their catalytic activity,” Journal of Physics and Chemistry of Solids, vol. 73, pp. 982–986, 2012.
[28]
H.-S. Zhang and K. Komvopoulos, “Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization,” Review of Scientific Instruments, vol. 79, no. 7, Article ID 073905, 2008.
[29]
A. C. Ferrari and J. Robertson, “Interpretation of Raman spectra of disordered and amorphous carbon,” Physical Review B, vol. 61, no. 20, pp. 14095–14107, 2000.
[30]
F. Tuinstra and J. L. Koenig, “Raman spectrum of graphite,” Journal of Chemical Physics, vol. 53, no. 3, pp. 1126–1130, 1970.
[31]
N. Tian, Z.-Y. Zhou, S.-G. Sun, Y. Ding, and L. W. Zhong, “Synthesis of tetrahexahedral platinum nanocrystals with high-index facets and high electro-oxidation activity,” Science, vol. 316, no. 5825, pp. 732–735, 2007.
[32]
I. A. Wani, S. Khatoon, A. Ganguly, J. Ahmed, A. K. Ganguli, and T. Ahmad, “Silver nanoparticles: Large scale solvothermal synthesis and optical properties,” Materials Research Bulletin, vol. 45, no. 8, pp. 1033–1038, 2010.
[33]
I. Pastoriza-Santos and L. M. Liz-Marzán, “Reduction of silver nanoparticles in DMF. Formation of monolayers and stable colloids,” Pure and Applied Chemistry, vol. 72, no. 1-2, pp. 83–90, 2000.
