Fractal characterization of flakes covered tuberose structured Cu:Sr(OH)2 thin film as supercapacitive electrode

Abstract The surface morphology plays a very important role in the performance of supercapacitive properties. The concept of fractal analysis, using the Higuchi algorithm, has been applied to study the surface morphology of Cu doped Sr(OH)2 thin films. The hierarchical tuberose with flakes structures of 1, 2 and 3 at.% Cu doped Sr(OH)2 morphologies have been synthesized by an easy and economical chemical route, namely, successive ion layer adsorption and reaction (SILAR) technique. The structural analysis and qualitative morphological studies have been done by XRD and SEM technique respectively and the relationship between crystallite size and the supercapacitive property has been explored. Higuchi algorithm has been used to study the fractal characterization of SEM micrographs of prepared samples. It has been observed that 3 at.% Cu doped sample has the highest value of fractal dimension as 1.6922 and specific capacity of 817 C g−1 for 0.4 mA current rate. The Hurst exponent for 3 at. % Cu: Sr(OH)2 is 0.3078, which is less than 0.5 that shows the anti-persistent behaviour, i.e., signifies the height variations at neighbouring pixels are negatively correlated. Further, the Bode plot and the capacitive behaviour of the electrode have been studied by the complex capacitance method. The results obtained using the fractal analysis for the deposited materials agree with the electrochemical characterization.