Study on the Electrochemical Kinetics of Manganese Dioxide/Multiwall Carbon Nanotube Composite by Voltammetric Charge Analysis

Electrochemical properties of MnO2/multiwall carbon nanotube (MWCNT) composites were investigated by using cavity microelectrodes (CME). Electrochemical kinetics of the MnO2/MWCNT composites were studied by analyzing the scan rate dependence of voltammetric charge, which was measured by cyclic voltammetry (CV) at various scan rates ranging from 20 mV s−1 to 1000 mV s−1. Based on several mathematical models, the relationship between voltammetric charge and scan rate was interpreted systematically. At slow scan rates, ion diffusion in MnO2 dominantly determined the rate of the overall electrochemical process. However, the faradaic reaction of Mn3+/Mn4+ at the MnO2 surface competed with mass transfer in terms of kinetics when the potential scan rate was higher than 400 mV s−1.