Self-assembled and highly faceted growth of Mo and V doped ZnO nanoflowers for high-performance supercapacitors

The rational design of metal ion-doped transition metal oxides has been considered as a novel electrode material for the development of high-performance asymmetric supercapacitors (ASCs). Herein, we facilely synthesized molybdenum and vanadium doped zinc oxide (Mo- and V-doped ZnO) lotus flower-like hierarchical structures using the co-precipitation method for use as a high capacity cathode material for ASCs. The formation mechanism during the self-assembly growth and highly faceted Mo- and V-doped ZnO lotus flowers were examined. Utilizing the beneficial properties of high electrochemical conductivity and excellent electroactive area, Mo- and V-doped ZnO lotus flowers demonstrated maximum specific capacities of 336 C g−1 and 362 C g−1 with good cycling stability. Furthermore, the ASC has been fabricated with V-doped ZnO as a cathode and activated carbon as a negative electrode, which shows a high specific capacitance of 111 F g−1, an energy density of 32.4 Wh kg−1, and a power density of 5.16 kW kg−1, respectively. The fabricated device also demonstrated excellent electrochemical capacitance retention of 85% and Coulombic efficiency of 98% after 2000 cycles. These superior characteristics indicate the promising potentiality of the new materials reporting for low-cost and high-performance supercapacitors.