Morphology evolution in anodically electrodeposited manganese oxide nanostructures for electrochemical supercapacitor applications—Effect of supersaturation ratio

Abstract

An in-depth study of morphology-controlled growth of manganese oxide nanostructures from acetate-containing aqueous solutions was carried out. By varying the deposition parameters, including solution composition, pH value, deposition temperature and current density, a series of manganese oxide nanostructures, including continuous coatings with equiaxed and fibrous features, petal- and flower-like morphologies, discrete oxide clusters, columnar structures and interconnected nanosheets, were anodically deposited on Au-coated glass. Detailed results on the morphology, chemistry and crystal structure of the as-deposited manganese oxide nanostructures suggest that the rich morphology of manganese oxide obtained is primarily determined by the influence of supersaturation ratio on reaction kinetics in the aqueous solutions. The electrochemical properties (specific capacitance, rate capacity and electrochemical impedance response) of manganese oxide nanostructures are carefully examined. The experimental results show that manganese oxide electrodes with oriented nanostructures, such as a columnar structure and an interconnected nanosheet architecture, exhibit enhanced electrochemcial performance by improving manganese oxide utilization.