Structural, morphological, optical, and electrochemical properties of Co-doped CeO2 thin films

Abstract

Undoped and Co-doped cerium dioxide (CeO2)thin films with different doping rates (x = 2, 4, 6%) were successfully elaborated using the spray pyrolysis (SP) technique on the glass substrate at the optimized temperature (450 ± 5) °C. Cobalt effect on microstructural, morphological, optical, and electrochemical behavior of CeO2 material was studied using X-ray diffractometer (XRD), micro-Raman spectroscopy, scanning electron microscope (SEM), energy dispersive analysis by X-ray (EDS), UV–Vis–NIR spectrophotometer, and Volta Lab system (VM4). XRD pattern shows the cubic structure fluorite type of the prepared samples, with (111) as preferred orientation. Raman spectra confirm XRD findings by the peak located at 462 cm−1 which corresponds to the active mode F2g of the cubic fluorite structure and reveal a small band after F2g mode coming from the vacancy oxygen. SEM images show densely uniform grains with some cracks and aggregates. EDS data confirm the presence of Ce, O, and Co elements in elaborated samples. The optical results show good transparency in the visual domain (≃70%) and a band gap starting from 3.18 eV for the undoped sample and decreases with increasing Co rate to attain 2.82 eV for 6%. Cyclic voltammetry results reveal that doping with Co increases the ion storage capacities of samples. The computational data obtained using WIEN2k software support our experimental results.