Fig. 9

Optical properties of the samples. a PL spectrum of rod-like CdS crystallites. b PL spectrum of flower-like CdS crystallites. c Diffuse reflectance spectra of rod-like CdS, flower-like CdS, and CdO@CdS heterostructure. d Tauc plots of rod-like CdS, flower-like CdS, and CdO@CdS heterostructure for evaluating the optical band gap values