Effect of annealing temperature on the structural, optical and dye degradation properties of cadmium sulfide thin films

Abstract

The significant extraction of organic compound from waste water with photocatalysis has become an ecological and environmental challenge in recent years, Herein; CdS (Cadmium Sulfide) thin films with different annealing temperature i.e. 200, 300, 400 and 500 °C were prepared by using Sol-Gel dip coating technique on glass substrates. Different parameters like substrate, precursors and annealing temperature can be influence the growth of CdS thin films. The analysis of XRD pattern shows that the prepared CdS films are orthorhombic structure and SEM image shows good quality film formation on substrate surfaces and cubic like morphology was observed. An optical analysis confirm that, in the UV and visible region can have a strong absorbance and clear deposits and with increasing annealing temperature between 200 and 500 °C and the energy of the band gap is reduced from 3.75 to 3.33 eV. XPS finding show that CdS thin film annealed at 500 °C provide high intensity binding than other prepared CdS thin films. The annealing temperature between from 200 to 500 °C note that crystallinity can be increased as the temperature increases, therefore; the enhanced crystalline size may be increases the intensity of array luminescence and result in enhanced recombination processes which is more suitable for dye degradation. The photocatalytic degradation of prepared CdS thin films was evaluated for methylene blue (MB) dye under visible light irradiation and improved efficiency of MB dye degradation is observed on CdS thin film annealed at 500 °C. This result shows that the resistance to charge transfer was less than the annealing temperature between 200 and 400 °C under visible light irradiation.