Synthesis, characterization, and transport properties of Nafion-polypyrrole membrane for direct methanol fuel cell (DMFC) application

Due to their distinctive chemical, electronic, and environmental properties, polypyrrole is used as a blocking barrier for methanol leakage in direct methanol fuel cells. Here, a straightforward deposition method of polypyrrole deposition on Nafion has been achieved by chemical polymerization in an aqueous medium. The chemical polymerization has been carried out during 1 h and 24 h; thus, the effect of the polypyrrole coating has been studied toward the leakage of methanol by cyclic voltammetry. It was found that the diffusion of methanol has been reduced for at least to three decades in comparison to commercial Nafion. The effect of the polypyrrole (PPy) coating on transport properties such as water uptake, ion exchange capacity, and proton conductivity has been investigated. Scanning electrochemical microscopy (SECM) has been used to investigate quantitatively the membrane proton conductivity. A potentiometric tungsten microelectrode, positioned above the membrane, was used to monitor directly the diffusion of H+. The chemical and morphological characterization of PPy coating has been characterized by Fourier transform infrared FTIR-ATR spectroscopy, X-ray photoelectron (XPS), scanning electron microscope (SEM), and atomic force microscopy (AFM).