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For application in a supercapacitor as electrodes, nano-scaled manganese oxide films were deposited on titanium substrates in manganese acetate solution using the hydrothermal electrochemical process. The effects of synthesis temperature, pH, and the concentration of manganese acetate on the material characteristics and capacitive behavior of manganese oxide film were investigated. The complex tri- and divalent hydrous manganese oxides examined using X-ray photoelectron spectroscopy (XPS) and Raman scattering spectroscopy were obtained at 60 °C in 0.2 M neutral solution. A maximum specific capacitance (SC) of 244 F g-1 was measured using cyclic voltammetry (CV) at 25 °C in 0.1 M Na2SO4 within the range of 0–1 V. The nanometer scale surface morphology of the film was altered by varying the synthesis temperature, pH, and the concentration of the solution. In addition to the surface morphology, the extent of hydration in the manganese oxide film also affected the capacitive properties.

Nanometer-scale manganese oxide films were synthesized at various temperatures in the range of 60–150 °C using the hydrothermal electrochemical deposition method. Field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to verify that the deposits were tri- and divalent hydrous manganese oxides. The electrochemical performance of manganese oxide films was examined by cyclic voltammetry (CV) in the range of 0.0–1.0 V [versus saturated calomel electrode (SCE)] in 0.1 M Na2SO4 solution at 25 °C. The specific capacitance (SC) increased with decreasing synthesis temperature, with a maximum value of approximately 244 Fg-1 at 60 °C. Crystalline manganese oxide prepared at 150 °C improved stability of capacitive performance, which only decreased by 4% after 800 cycles. The SC depended not only on the surface morphology but also on the amount of hydration in the manganese oxide structure. The deposited manganese oxide has the chemical formula Mn3O4nH2O (n~1.2), as established using thermogravimetric and differential thermal analysis (TG/DTA).