Comparative Study of Electrochemical Methods for Determination of Methanol Permeation Through Proton-Exchange Membranes

In this work, methanol permeation rates were measured using various electrochemical techniques, namely, cyclic voltammetry, chronoamperometry and potentiometry. For all the methods, a Nafion(A (R)) 117 membrane was used to measure and evaluate methanol crossover rates. The purpose of this study is to compare the methanol permeation data obtained using the above-mentioned techniques under identical conditions, compare the data with the literature data, and then suggest the most accurate and reliable method for the determination of methanol crossover rates. The permeability values using these techniques were found to be in the range 1.11 x 10(-6) to 1.27 x 10(-6) cm(2)/s. The permeability values obtained using these techniques are close to one another and also compare well with the literature data for similar conditions; however, after careful screening of the data, it was found that the potentiometric technique is the easiest in terms of experimentation, reproducibility of results and accuracy, and gives more data points. This technique is suggested to be the best and most accurate for studying methanol permeation rates through membranes for direct methanol fuel cell applications.