Cu nanoparticles induced structural, optical and electrical modification in PVA

Abstract

Cu nanoparticles were synthesized in PVA matrix by chemical reduction of cupric nitrate with hydrazine hydrate. Structural characterization of synthesized Cu–PVA nanocomposite was carried out using UV–Visible Spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Appearance of characteristic surface plasmon resonance peak of Cu nanoparticles at 591 nm in absorption spectra of Cu–PVA colloidal solution confirms the formation of Cu nanoparticles. TEM investigation indicates that Cu nanoparticles of size 16 nm are formed in PVA matrix which are in agreement with the size obtained using X-ray diffraction. Morphology of Cu–PVA nanocomposite was further confirmed using SEM. Analysis of UV–Visible absorption and reflection data indicates towards the reduction in optical band gap and increase in refractive index of the resulting nanocomposite. The synthesized Cu–PVA nanocomposite has been found to be more conducting than PVA as ascertained using I–V studies. The decrease in band gap and increase in conductivity can be correlated due to the formation of localized electronic states in PVA matrix due to insertion of Cu nanoparticles. Photoluminescence measurements showed strong blue visible emission peak at 450 nm at different excitation wavelengths in the range of 220–245 nm.