Self-assembly formation of NiCo2O4 superstructures with porous architectures for electrochemical capacitors

Abstract

Nickel cobalt oxides (NiCo₂O₄) superstructures with microsized flowers (MF), nanoflowers (NF), nanoneedles (NN), and nanospheres (NS) have been prepared by a facile self-assembly formation and subsequent conversion process. The various morphologies of the nickel cobalt precursors (NCP) are tuned by using different salts, solvents, surfactants and reaction temperatures. The as-obtained NCP can be readily converted to NiCo₂O₄ through an annealing process with their structures well retained. The electrochemical properties of the as-derived NiCo₂O₄ are assessed as the active electrode materials. The results indicate that the NiCo₂O₄ has exhibited promising pseudo-capacitive properties with high capacitance and good cycling stability. The NF has delivered the highest specific capacitance of 636 F g⁻¹ (at a rate of 1 mV s⁻¹) among all the four samples, showing its potential application for next generation electrochemical capacitors.