Tuning the Redox Properties of the Nanostructured CoMoO 4 Electrode: Effects of Surfactant Content and Synthesis Temperature

A systematic study was performed to examine the effects of surfactant content and synthesis temperature on the morphologies and the redox properties of cobalt molybdate (CoMoO 4 ). The results revealed that varying the concentration of surfactant (F127) varies the morphology from nanorods to nanospheres and nanoneedles. A concentration of metal‐to‐surfactant ratio of 1:1 outperformed that of 1:0.5 and 1:2 ratios in specific capacitance, energy density and cycling stability. The surfactant at the optimised ratio significantly influenced the morphology and particle size of the CoMoO 4 material and acted as a template, whereas increasing the synthetic temperature did not contribute much to the energy storage. An asymmetric supercapacitor was fabricated based on CoMoO 4 as the positive electrode and activated carbon as the negative electrode in 2  m NaOH electrolyte. The CoMoO 4 material synthesised at 300 °C in the presence of F127 (1:1) showed a specific capacitance of 79 F g −1 and an energy density of 21 W h kg −1 when tested as a hybrid device. This suggests that the redox activity and its storage capability depend on the surfactant content as well as its self‐assembly behaviour. CoMoO 4 showed excellent cycling stability retaining over 75 % of its initial capacitance after 2000 cycles, which makes it a very promising candidate for large‐scale energy‐storage applications.