Graphene oxide — Nafion composite membrane for effective methanol crossover reduction in passive direct methanol fuel cells

摘要

Direct methanol fuel cells (DMFC) are promising candidates for small-scale portable applications. They are characterized by their high energy density that is ten times higher than that of the lithium ion batteries. Hence, they have the potential to be prosperous alternatives to replace secondary batteries. However, their performance is limited by the Methanol crossover (MCO) through the electrolyte membranes especially at high methanol concentration. Consequently, the development of a new membrane to minimize MCO is considered to be a crucial improvement toward commercialization of DMFC. In this study, a composite membrane of graphene oxide (GO)/Nafion 117 was synthesized. The performance of this composite membrane in a DMFC was studied. This composite membrane was prepared by depositing a thin film of GO on Nafion 117 membrane. GO was synthesized in the laboratory from graphite using modified Hummer's method. The composite membrane was characterized using X-ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and Electrochemical Impedance Spectroscopy (EIS). The Nafion-GO membranes were tested in a direct methanol fuel cell with 2 M and 5 M methanol concentrations. Preliminary results showed an improvement in the fuel cell performance and a decrease in methanol crossover when GO-Nafion membranes were used.