Enhanced electrochemical performance of ZnO modified by Y2O3 for application in supercapacitors

Abstract

Zinc oxide (ZnO) is a non-toxic semiconductor known for its broad optical band gap and versatility in industrial and medical applications. This study explores the electrochemical properties of pure ZnO modified by making its composite with Y₂O₃. Three composite samples were prepared by adding 2 %, 5 %, and 8 % Y₂O₃ in pure ZnO. X-ray diffraction was used to characterize each sample for phase and structural investigation. The ZnO sample is found in its pure hexagonal phase, while the composites exhibit phases of both ZnO and Y₂O₃. Crystallite size calculations from XRD indicated that all samples are bulk in nature. Galvanostatic charging and discharging (GCD) curves at varying current densities, electrochemical impedance spectroscopy (EIS), and cyclic voltammetric study (CV) at various scan rates were used to investigate the electrochemical characteristics. CV plots of all samples show clear redox peaks and changes in capacitance with scan rate. The charge storage mechanism in all samples involves a mixture of double-layer capacitance and pseudocapacitive behaviour. According to the GCD curve, composites have higher specific capacitance than pure ZnO. The specific capacitance rises from 277 F/g to 449 F/g as the Y₂O₃ concentration is increased from 2 % to 5 % at a current density of 2A/g and for 8 % Y₂O₃ it becomes 467 F/g. Lower charge transfer resistance is demonstrated by ZnO after incorporation of 5 % and 8 % Y₂O₃, suggesting improved electrochemical stability and enhanced performance for supercapacitor applications.