Abstract
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.
Highlights
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]
No peaks corresponding to oxides of Ag, Au, or Cu are observed within the detectable limit of X-ray diffraction (XRD)
(a) Fine nanoparticles (Ag, Au, and Cu) decorated graphene can be prepared by chemical synthesis
Summary
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]. 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 (2 × 105 cm2/Vs) [5], and specific surface area 2630 (m2/g) [6]. A number of different ways of preparing graphene have been reported in the literature [10]. This includes micromechanical exfoliation of graphite [11], chemical vapor deposition [12], and chemical methods to create colloidal suspension [13]. Unless these sheets are well separated from each other, the graphene sheets tend to form
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