Photoluminescence from SWCNT/Cu Hybrid Nanostructure Synthesized by a Soft Chemical Route

We report a simple wet chemical technique to coat single wall carbon nanotubes (SWCNTs) with Cu nanoparticles. The SWCNT/Cu hybrid nanostructure has been characterized using field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD) study, and Raman spectroscopy. Characteristic optical properties of the nanohybrid structure have been identified through UV-Vis and photoluminescence (PL) spectroscopy. When excited by a radiation of 400？nm wavelength, PL emission in the visible range of 480–620？nm was observed due to charge transfer. This property may be exploited in photovoltaic cells, solar energy conversion, and sensor devices. 1. Introduction Carbon nanotubes (CNTs), with their exceptional electrical, mechanical, and optical properties [1–3], have drawn much attention of the researchers in the field of nanotechnology. On the other hand nanoparticles have attracted the researchers because of their unique chemical and physical properties [4, 5]. CNTs hybridized with metal nanoparticles bring forth a new class of nanostructured materials into focus [6–8] because of their unique resultant physical properties. Such CNT/metal nanohybrid materials find wide application in sensor devices [9], as catalysts for fuel cells [10, 11], in solar cells [12, 13], as fillers [14, 15], and so forth. Composites of metal nanoparticles and CNTs have been synthesized by various techniques, which include direct coating or deposition on CNTs of metal nanoparticles, such as Ag, Au, Cu, Pd, and Pt. Several methods such as solid-state reactions, capillary action, radiolysis, physical evaporation, electroless deposition, physisorption, self-assembly, and colloidal chemistry combined with electrostatic interactions or with sonication in aqueous solution [16] have been adopted. Zhang et al. [17] fabricated carbon nanotubes with totally filled Cu-nanowires by methane decomposition using Cu-microgrid as a catalyst. Reddy et al. [16] developed a new method for the synthesis of Cu2O-coated multiwall carbon nanotubes (MWCNTs) on the basis of Fehling’s reaction. Fabrication of MWCNT-reinforced Cu matrix composite for heat sink application was reported [18]. But only a few reports have been made on simple and efficient routes for strongly attaching noble metal nanoparticles or nanospheres to CNTs [19, 20]. Decoration of SWCNTs with extremely tiny (2-3？nm) monodispersed noble metal nanoparticles by cost-effective lucid chemical process is still a challenging task [21]. Here,