Hydrothermally synthesised novel α-Bi2O3-ZnO heterojunctions for high performance supercapacitor application

Abstract

Supercapacitors are a viable alternativefor next-generation sustainable energy storage systems, but their capacitance muststill be improved by selecting an appropriate electrode material. Hereinwe devised a cost effective, one-step hydrothermal technique to fabricateporous α-Bi2O3-ZnO heterojunction composites with a high aspect ratio. The prepared materials were systematically characterized through X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analysis. Electrochemical measurements revealed that in contrast to pristine α-Bi2O3 and ZnO nanostructured electrodes, the proposed α-Bi2O3-ZnO heterojunctions demonstrated robust pseudocapacitance performance owing to the synergistic effect, convenient ion transport channels and more exposed surface area. At a scan rate of 10 mVs−1, the α-Bi2O3-ZnO supercapacitor electrode exhibited a high specific capacitance of 582.5 Fg−1 and outstanding long-term cycling stability by maintaining approximately 86.3% of its original charge after 3000 cycles. Furthermore, an asymmetric supercapacitor based on α-Bi2O3-ZnO positive electrode and activated carbon was constructed whichdemonstrated high specific capacitance (74.03 Fg−1 at 8 mAcm−2) and renderedmaximum energy densityof 23.13 Whkg−1 at 607.5 Wkg−1, making it a useful and promising material for electrochemical energy storage applications.