Semiconductor Properties of Electrodeposited Manganese Dioxide for Electrochemical Capacitors: Mott-Schottky Analysis

Herein the semiconducting nature of electrodeposited manganese dioxide (gamma-MnO2) is examined for its effects on pseudo-capacitive electrode behaviour in neutral electrolytes. Electrochemical analysis of the manganese dioxide electrode is achieved using a combination of cyclic voltammetry (CV), step potential electrochemical spectroscopy (SPECS) and electrochemical impedance spectroscopy (EIS), in particular the combination of SPECS and EIS in a single experiment, enabling the determination of electronic properties across the full potential window. After establishing stable cycling with CV, electrode performance is examined using SPECS. EIS data, recorded under quasi-equilibrium conditions at the end of each potential step rest period, is then analyzed using the Mott-Schottky equation, leading to the identification of both n-type and p-type behaviour for the manganese dioxide electrode. Flat band potentials are determined (V-fb,V-n = -0.34 V vs SCE and V-fb,V-p = 0.98 V vs SCE), and conclusions about the electrochemically active surface area being more closed related to the geometric surface area were reached.

Automated summary

This study examined the semiconducting nature of electrodeposited manganese dioxide (gamma-MnO2) and its effects on pseudo-capacitive electrode behavior in neutral electrolytes through a combination of cyclic voltammetry, step potential electrochemical spectroscopy, and electrochemical impedance spectroscopy. The analysis of EIS data using the Mott-Schottky equation revealed both n-type and p-type behavior for the manganese dioxide electrode, with determined flat band potentials. The study concluded that the electrochemically active surface area was more closely related to the geometric surface area.