Investigation of Electrochemical Performance of NiO Nano Rods/Plates Prepared by Cathodic Electrochemical Deposition—Heat-treatment (CEDHT) Method

In pseudocapacitors, the structure of electrode materials plays an important role in determining the electrolyte accessibility and electrode stability, and thus the device performance. To this end, extensive research efforts have been devoted to the control of structures of NiO electrode materials. Uniform NiO structures in a variety of forms, such as nanocapsules and nanoparticles have been found that exhibit superior supercapacitive performance [1,2]. Up now, nanostructured NiO has been produced by electrochemical deposition (ED) methods including anodic and cathodic routes. In this research, cathodic electrochemical deposition-heat treatment (CED-HT) was used as an effective method for synthesis of nanostructured NiO. In this way, nickel hydroxide precursor was first deposited through CED step. Then, the final oxide was obtained by applying the HT procedure. The structural and morphological evaluations by XRD and SEM revealed that the prepared oxide has crystalline NiO structure (Fig. 1a) with mixed rod/plate texture at nanoscale (Fig. 1b). The supercapacitive performance of the prepared NiO nanoplates/rods was studied by techniques of cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) within the potential window of -0.1 to 0.5V in 1 M KOH electrolyte. The measurements (Figs. 1c and d) revealed that the prepared sample have high reversibility (ΔEp =15 mV), high specific capacitance (1265 F g–1 at 1 A g–1) and proper long-term cycling stability of 92.4% capacity retention after 3000 cycling at the current density of 1 A g–1. 237