High-Performance Supercapacitor Stability and Capacitance Enhancements Using Ultrasonic-Assisted Synthesis of Cr2O3-ZnO Nanocomposites

Abstract

An extensive examination of composite electrode materials is essential for advancing supercapacitors with elevated specific capacitance and outstanding stability. This study introduces a straightforward and effective technique that utilizes ultrasonic-assisted chemical precipitation to create a nanocomposite of Cr2O3 NPs bonded to ZnO nanosheets (Cr2O3-ZnO NCs). XRD spectra indicate that Cr2O3 is consistent with JCPDS card No. 38-1479, whilst ZnO nanosheets are in agreement with JCPDS card No. 36-1451. HR-TEM analysis reveals that the Cr2O3 NPs in the Cr2O3-ZnO NCs have diameters ranging between 14.5–16.7 nm. The CV profiles within 10–200 mV/s scan rates exhibit well-defined redox pair reactions with no distortion in the integrated area. According to the studies of Trasatti and Dunn’s, 90.94% of the charge distribution is caused by capacitance, whereas 9.05% is a result of diffusion. The GCD plots demonstrate that Cr2O3-ZnO NCs exhibit a 926.6 F/g (specific capacitance) when subjected to a current density of 1 A/g. Furthermore, these NCs retain 83.3% of their initial capacitance even after undergoing 2000 charge and discharge cycles. The improved achievement is ascribed to the existence of Cr2O3 NPs which boost conductivity, promote pseudocapacitive processes, and hinder the aggregation of ZnO nanosheets by serving as spacers. The features of Cr2O3-ZnO NCs make them highly promising for use in supercapacitor applications.