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

Electrochemical properties of MnO 2 /multiwall carbon nanotube (MWCNT) composites were investigated by using cavity microelectrodes (CME). Electrochemical kinetics of the MnO 2 /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 MnO 2 dominantly determined the rate of the overall electrochemical process. However, the faradaic reaction of Mn 3+ /Mn 4+ at the MnO 2 surface competed with mass transfer in terms of kinetics when the potential scan rate was higher than 400 mV s −1 .