Polyelectrolyte Membranes Based on Nafion/Chitosan Blends for Direct Methanol Fuel Cell Application

In this study, polyelectrolyte membranes (PEMs) were fabricated by blending chitosan and Nafion with various compositions for direct methanol fuel cell (DMFC) application. The incorporation of Nafion caused increasing the glass transition temperature (T_g), as well as decreasing the crystallinity of chitosan based matrix, which has roots in the attractive interaction between -SO₃H groups in Nafion and -NH₂ groups in chitosan structure. In addition, the proton conductivity, as well as the methanol permeability of the studied membranes increased with an increase in the loading weight of Nafion. The selectivity parameter (the ratio of proton conductivity to methanol permeability) of the membrane containing 25 wt% of Nafion was comparable to neat Nafion. In parallel, the results of the DMFC performance test showed a maximum power density of 39 mW cm⁻² at 319 mA cm⁻² current density (at 5 M methanol concentration and 75 °C) for the mentioned membrane which is near to that for recast Nafion. The results showed that the chitosan/Nafion complex can be considered as a PEM for DMFC application.