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

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 Cr 2 O 3 NPs bonded to ZnO nanosheets (Cr 2 O 3 -ZnO NCs). XRD spectra indicate that Cr 2 O 3 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 Cr 2 O 3 NPs in the Cr 2 O 3 -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 Cr 2 O 3 -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 Cr 2 O 3 NPs which boost conductivity, promote pseudocapacitive processes, and hinder the aggregation of ZnO nanosheets by serving as spacers. The features of Cr 2 O 3 -ZnO NCs make them highly promising for use in supercapacitor applications.