The effect of ultrasonic treatment and deposition time on nanoflake-like Co(OH)2 thin films were prepared using the potentiostatic mode of electrodeposition method on stainless steel substrates by a nitrate reduction reaction. After ultrasonic treatment, we used stainless steel substrates for deposition of the nanoflakes like Co(OH)2 thin films. The effect of deposition times and electrolytes on different physico-chemical properties of Co(OH)2 was investigated in detail, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and electrochemical testing. After ultrasonic treatment Co(OH)2 thin films had devolvement of the uniform and interconnected formation of nanoflakes nanostructures. Supercapacitor performance of the Co(OH)2 electrodes suggest that, specific capacitance are depends on the surface morphology, and Co(OH)2 electrodes after ultrasonic treatment exhibited higher performance than without ultrasonication. The maximum specific capacitance of the 30 min. deposited Co(OH)2 nanoflakes exceeded 276 Fg-1 in 0.5M KOH electrolyte at 5 mVs-1 scan rate.

The manganese oxide graphene oxide (Mn ₃ O ₄ /rGO) composite heterojunction with copper oxide is useful for the production of an electrochemical supercapacitor. The graphene oxide and manganese oxide composite have been synthesized by adopting a method of co-precipitation. The composite of Mn ₃ O ₄ /rGO was synthesized with different concentrations of Mn ₃ O ₄ and rGO. The structural, morphological, electrochemical and supercapacitive properties of Mn ₃ O ₄ /rGO composite have been examined. The electrochemical and supercapacitive properties have been studied with regard to different substrates. The Mn ₃ O ₄ /rGO composite was deposited on different substrates such as steel, copper and brass. The CuO/Mn ₃ O ₄ /rGO shows relatively better specific capacitance (856 F g ⁻¹ ) and better stability (82% retention after 2000 cycles) than other substrates used. The present work describes the development of cost-effective and high-performance CuO/Mn ₃ O ₄ /rGO-based nanomaterials for supercapacitors. The CuO/Mn ₃ O ₄ /rGO composite can be used as a flexible supercapacitor device.