Synthesis of Ag/polyaniline nanocomposite via an in situ photo-redox mechanism

Silver/polyaniline nanocomposites are prepared via in situ reduction of silver salt in aniline by mild photolysis performed with 8 W long wavelength (365 nm) and short wavelength (254 nm) radiation from UV lamp. Reduction of the silver salt in aqueous aniline leads to the formation of silver nanoparticles which in turn catalyze oxidation of aniline to polyaniline. Systematic observation of the progress of the reaction by means of absorption spectroscopy revealed that the reaction completes faster under the UV light of 254 nm wavelength than the visible source of 365 nm. The absorption bands of the reaction solution revealed that the bands at about 400-420 nm due to benzonoid ring of the polyaniline are overlapped and red-shifted due to the presence of nano-silver in powdered state. A slightly broadened X-ray diffraction (XRD) pattern indicating, small particle size (∼30 nm), is consistent with cubic silver. Scanning electron microscopy (SEM) of the nanocomposite showed a uniform size distribution with spherical and granular morphology. Thermogravimetric analysis (TGA) showed that the composites have a higher degradation temperature than polyaniline alone.