Shape‐Controlled Synthesis of NiCo2O4 Microstructures and Their Application in Supercapacitors

The shape‐controlled synthesis of NiCo₂O₄ microstructures through a facile hydrothermal method and subsequent calcinations was explored. By employing CoSO₄, NiSO₄, and urea as the starting reactants, flower‐like NiCo₂O₄ microstructures were obtained at 100 °C after 5 h without the assistance of any additive and subsequent calcination at 300 °C for 2 h; dumbbell‐like NiCo₂O₄ microstructures were prepared at 150 °C after 5 h in the presence of trisodium citrate and subsequent calcination at 300 °C for 2 h. The as‐prepared NiCo₂O₄ microstructures were characterized by X‐ray powder diffraction, field‐emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and (high‐resolution) transmission electron microscopy. Both the flower‐like and dumbbell‐like NiCo₂O₄ microstructures could be used as electrode materials for supercapacitors, and they exhibited excellent electrochemical performance, including high specific capacitance, good rate capability, and excellent long‐term cycle stability. Simultaneously, the shape‐dependent electrochemical properties of the product were investigated.