Effect of simultaneous electrochemical deposition of manganese hydroxide and polypyrrole on structure and capacitive behavior

Publication date: Available online 7 January 2020Source: Journal of Electroanalytical ChemistryAuthor(s): Tamene Tamiru Debelo, Masaki UjiharaAbstractNanocomposite electrodes were prepared by single-phase galvanostatic electrodeposition on a stainless-steel mesh in an aqueous solution of manganese nitrate and pyrrole. On the anode, the deposited film (anodic film) was composed of spherical particle aggregates of almost pure polypyrrole, which strongly adhered to the stainless steel. In contrast, highly porous nanosheets of Mn(OH)2 effectively formed on the cathode and became Mn oxides with a trace of carbon material after calcination at 200 °C (calcined cathodic film). Both the obtained anode and calcined cathodic films on the stainless-steel meshes were characterized as capacitive materials. The anodic film showed capacitive behavior, while the calcined cathodic film exhibited a more pseudocapacitive nature. The specific capacitance of the anodic and calcined cathodic films was analyzed from the CV curves (510 and 270 F/g at 5 mV/s) and galvanostatic charge-discharge curves (430 and 220 F/g at current densities of 0.27 A/g and 0.23 A/g, respectively). During the cycle test, the calcined cathodic film gradually increased the capacitance due to ion diffusion into the MnO2 nanostructures over time, while the polypyrrole in the anodic film repeated adsorption/desorption of dopant ions during the redox processes, which led to degradation of the capacitive properties.Grap...
Source: Journal of Electroanalytical Chemistry - Category: Chemistry Source Type: research