N-doping SrTiO3@SrCO3 heterostructure electrode: Synthesis, electrochemical characterization, and varistor application

Abstract

Optical traditional techniques, such as diffusive reflectance spectroscopy, are used to confirm absorption behavior modification after anion doping process. However, the doping process in some materials as a SrTiO3 semiconductor was not clearly proved in different anions doping cases through traditional techniques. In this case, supporting technique as electrochemical measurements could prove a great help in elucidating the doping process modifications in the semiconductor material. In this paper, the electrochemical characterization was applied to analyze changes in energy bands produced by N-doping in SrTiO3@SrCO3 composite thin film electrodes. SrTiO3@SrCO3 and N-doped SrTiO3@SrCO3 nanoparticles were first characterized by X-ray diffraction to confirm a perovskite crystalline structure in both materials, whereas diffusive reflectance spectroscopy was used to demonstrate that no modification in the absorption spectrum is evident after doping. The thin films were observed by FESEM/SEM, and its deposition parameters were electrochemically evaluated. The electrochemical profiles of SrTiO3@SrCO3 and N doped SrTiO3@SrCO3 thin film electrodes were compared in dark and under UV-C light to determine the photocurrent. These measurements presented distinct results for the undoped and the doped materials, such as modification in photocurrent under UV-C illumination. SrTiO3@SrCO3 composite electrodes show important characteristics which could be classified as a potential candidate in varistor uses, especially in the low-voltage protection system. The presented results confirm that electrochemical methods are useful to analyze the synthesis efficiency to produce N-doped structures.