XANES analysis and structural properties of CdS-doped TiO2

The present paper reports on fabrication of the undoped and cadmium sulphide (CdS) doped titanium dioxide (TiO2) samples (1 wt% CdS-TiO2 and 2 wt% CdS-TiO2) and their characterization. Effect of the dopant on microstructural, optical and electronic properties of the fabricated samples are presented by X-ray diffraction (XRD), atomic force microscope (AFM), Raman spectra, UV-visible absorption spectra and X-ray absorption near edge spectroscopy (XANES). XANES spectra of the Ti L edges and O K edges of the CdS-TiO2 films revealed that with 2 wt% CdS doping in the TiO2, crystal structure changes from the anatase type to the rutile type. Ti L edges as well as O K edges both exhibits that 2 wt% CdS doping in TiO2 has modified the electronic structure of TiO2. Results of XRD and AFM show that crystallite size and roughness of the TiO2 significantly reduces with the CdS doping. It is observed from Raman spectra that the peaks shift towards higher wave number with increasing CdS contents indicating decrease in bond lengths. Optical band-gap for the undoped TiO2 is 3.33 eV and 2.71eV with 2 wt% CdS doped and it is found that absorption band-gap of TiO2 is red shifted to visible region.