Optical investigation of starch capped cadmium sulfide nanoparticles

Abstract Green synthesis using soluble starch as stabilizing agent in aqueous medium is an approach towards to develop an eco friendly method for synthesis of nanoparticles. It has advantages over conventional method involving toxic reagents. Cadmium sulfide is a suitable material among the II-VI compounds for optoelectronic and solar applications. We report a study on the optical properties of CdS nanocrystals prepared by green synthesis method. Cadmium sulfide nanoparticles were prepared using starch as stabilizing agent. The sample was characterized by X-ray diffraction, Scanning electron microscope, UV–Visible absorption spectroscopy, and photoluminescence spectroscopy. From the study, the blue shift in absorption wavelength with respect to bulk CdS indicate the increased in effective energy band gap and formation of nano sized CdS particles. The estimated size confirms the weak confinement regime as the size comparable to exciton Bohr radius. Photoluminescence spectrum shows band edge emission and deep trap states emission. The CdS nanoparticles exhibit photo catalytic activity against methyl orange under visible light irradiation. The 75% photo degradation was observed for 90 min irradiation time.