Morphologically modified CuO nanorod structure @ stainless steel as high performing supercapacitor electrode prepared by spray pyrolysis

Abstract

Copper oxide (CuO) nanorods are successfully grown onto the stainless steel substrates through varying different concentrations of non-aqueous Cu(NO3)2.3H2O by using the spray pyrolysis technique. Structural information and phase formation confirmation are carried out using X-ray diffraction. The as-grown nanorods possess a monoclinic crystal structure with the CuO phase. The growth of nanorods and morphological modifications with different molar concentrations are viewed through field emission scanning electron microscopy. It confirms morphological modifications from randomly oriented nanostructures to well oriented nano-cuboids with the increase in molar concentration of precursor solution. Further transmission electron microscopy confirms the agglomeration of interconnected nanograins to form nano-cuboids. It is observed that specific capacitance increases with an increase in the CuO nanorod size with the molar concentration of the precursor solution. As-prepared CuO electrode exhibits outstanding electrochemical performances with a capacitance of 827.40Fg-1. Encouragingly, morphologically modified CuO nanorod electrode achieves a maximum specific energy of 108.18Whkg−1 and outstanding cycling stability with 87.78% capacitive retention after 5000 cycles, which indicates a great potential for practical application. The diffusion coefficient of the electrolyte ions for the high performing CuO electrode is 2.75 × 10−17 cm2s−1, which is suitable for the supercapacitor application.