Optical characterization of CdS nanorods capped with starch

• Preparation of CdS nanorods with assistance of maize starch.
• The size of the nanorods has been controlled by changing the concentration of maize starch.
• CdS nanorods are uniform and of well crystalline.
• Absorbance peaks and emission peaks are shifted significantly for different samples.
• The optical band gap is being tuned by the size modification of the nanorods.

Well crystalline uniform CdS nanorods were grown by changing the concentration of maize starch. The highly polymeric (branched) structure of starch enhances the growth of CdS nanorods. The average diameter of the nanorods is 20–25 nm while length is of 500–600 nm as verified from SEM and XRD observations. The optical band gaps of the CdS nanorods are varying from 2.66 eV to 2.52 eV depending on concentration of maize starch. The photoluminescence (PL) emission bands are shifted from 526 nm to 529 nm with concentration of maize starch. We have also observed the enhanced PL intensity in CdS nanorods capped with starch. The Fourier transform infrared (FTIR) spectroscopy shows the significant effect of starch on CdS nanorods.