An insight into the electrochemical performance of cobalt-doped ZnO quantum dot for supercapacitor applications

摘要

Although ZnO QD has high energy density, higher surface-to-volume ratio, rapid charge transportation, and superior chemical and thermal stability, its poor electronic and ionic conductivity limits its opportunities as a supercapacitor device. In this study, Zn1-xCoxO (x = 0, 0.02, 0.04) samples were synthesized via the wet-precipitation method. The charge transfer between the doping metal element and the ZnO results in more active sites, a larger surface area, and more efficient diffusion pathways for both electron transfer and ion diffusion. Furthermore, doping causes oxygen vacancies in the host lattice, resulting in an increase in electrical conductivity. As a result, the x = 0.04 electrode demonstrated exceptional electrochemical supercapacitor performance, with a high specific capacitance of 697 F/g, excellent power and energy density (1026 W/kg and 24Wh/kg, respectively), and good cycling stability (capacitance retention of 97% after 2000 cycles). These results imply that cobalt-doped ZnO will be a suitable addition for next-generation supercapacitor applications.