Galvanostatically electroplated MnO₂ nanoplate-type electrode for potential electrochemical pseudocapacitor application

A manganese oxide (MnO₂) nanoplate-type electrode has been prepared using galvanostatic electrodeposition method with an aqueous manganese sulfate solution and characterized for its structural, morphological, compositional, and surface wettability studies and afterward envisaged in pseudocapacitor applications. The MnO₂, evidenced through Raman and X-ray photoelectron spectroscopy analysis, electrode composed of nanoplate-type surface morphology is hydrophilic and amorphous in nature. The electrochemical properties of MnO₂ are examined using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements in Na₂SO₄, NaOH, and KOH electrolytes, which demonstrate the pseudocapacitive signature with higher performance in Na₂SO₄ electrolyte than the others. A maximum specific capacitance of 804 F g⁻¹ at a scan rate of 5 mV s⁻¹ within −0.3–1.0 V potential range, with 84% retention after 1000 cycles, in 1 M Na₂SO₄ is evidenced.