Effect of growth time of hydrothermally grown cobalt hydroxide carbonate on its supercapacitive performance

• Hydrothermal synthesis of cobalt hydroxide carbonate by variation of growth time.
• Cobalt hydroxide carbonate exhibited nanorods morphology.
• Specific surface area of the cobalt hydroxide carbonate increases with reaction time.
• The composites exhibit good electrochemical performances as electrode for electrochemical capacitors.

We present the time-dependent synthesis of cobalt hydroxide carbonate nanorods by hydrothermal method with a systematic increase of different parameters such as specific surface area and specific capacitance as a function of different synthesis time. Morphological characterization of the cobalt hydroxide carbonate nanorods were carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that variation of the time of reaction plays a crucial role in the transformation of samples’ morphology. Cobalt hydroxide carbonate nanorods synthesized with 12 h reaction time, which is the reaction just before the materials transforms into cobalt oxide under the same synthesis conditions exhibited the highest specific capacitance of 466 F g−1 at a current density of 1 A g−1 in 6 M KOH electrolyte and also showed excellent stability with ∼99% capacitance retention after 2000 cycles at a current density of 10 A g−1. Based on the above results, the cobalt hydroxide carbonate nanorods show a considerable potential as electrodes materials for supercapacitor applications.