S. Annapurna, Y. Suresh, B. Sreedhar, A.K. Singh, G. Bhikshamaiah
Osmania University College for Women, India
pp. 265 - 268
Keywords: green synthesis, photoluminescence, copper, nanoparticles, potato starch, Ocimum sanctum
Copper nanoparticles are prepared using a two stage chemical reduction method. Potato starch and Ocimum Sanctum leaf extract are used to stabilize the copper nanoparticles. This approach is proved to be an efficient method for preparation of copper nanoparticles at room temperature and without using any inert atmosphere. The resulted powder samples were well characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Small Angle X-Ray Scattering (SAXS), UV-Visible Spectroscopy, X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. The prepared copper nanoparticles are found to be FCC crystalline, monodispersed and stable in air for around 25 days. The visible photoluminescence from metal nanoparticles is usually due to the interband transition between the sp conduction bands and the d bands. In the case of copper, its electronic structure can explain the photoluminescence behavior where 3d valence and 4sp conduction electrons play the role for fluorescence. Photoluminescence spectra of copper nanoparticles show an emission peak at 430 nm when illuminated at 325 nm. It has been found that the emission properties of the fluorescent molecules near a metal nanoparticle change significantly. The fluorescence of molecules in direct contact with the metal gets enhanced. Here adsorbed natural extract on the surface of copper nanoparticles can enhance the emission peak.