Synthesis of Cadmium Sulphide nanoparticles

Nanoparticles form a link between molecular and bulk state of matter and exhibit size dependent physical and chemical properties. A novel technique of synthesizing nanoparticle films on biological membrane substrates is presented here. Cadmium Sulphide (CdS) nanoparticles were prepared by the chemical reaction of aqueous solutions of Cadmium Acetate and Thiourea. The reacting solutions were allowed to diffuse across the membrane for different periods to control the deposition time. The optical absorption spectra of the membrane after the reaction were recorded with bare membrane as reference. The optical absorption spectra show a clear shift in the absorption edge for films with different deposition times at a fixed concentration. The band gaps calculated from the absorption spectra for films with smaller deposition time were higher than that for the bulk CdS. The particle size, estimated from the band gaps, lie in the nanometer range showing that the particle size and band gap can be tailored by controlling the deposition time and concentration of the precursors.