Influence of Graphene Oxide on the Ethanol Permeability and Ionic Conductivity of QPVA-Based Membrane in Passive Alkaline Direct Ethanol Fuel Cells

摘要

Passive alkaline–direct ethanol fuel cells (alkaline–DEFCs) appear to be suitable for producing sustainable energy for portable devices. However, ethanol crossover is a major challenge for passive alkaline–DEFC systems. This study investigated the performance of a crosslinked quaternized poly (vinyl alcohol)/graphene oxide (QPVA/GO) composite membrane to reduce ethanol permeability, leading in enhancement of passive alkaline–DEFC performance. The chemical and physical structure, morphology, ethanol uptake and permeability, ion exchange capacity, water uptake, and ionic conductivity of the composite membranes were characterized and measured to evaluate their applicability in fuel cells. The transport properties of the membrane were affected by GO loading, with an optimal loading of 15 wt.% and doped with 1 M of KOH showing the lowest ethanol permeability (1.49 × 10⁻⁷ cm² s⁻¹ and 3.65 × 10⁻⁷ cm² s⁻¹ at 30 °C and 60 °C, respectively) and the highest ionic conductivity (1.74 × 10⁻² S cm⁻¹ and 6.24 × 10⁻² S cm⁻¹ at 30 °C and 60 °C, respectively). In the passive alkaline–DEFCs, the maximum power density was 9.1 mW cm⁻², which is higher than commercial Nafion 117/KOH (7.68 mW cm⁻²) at 30 °C with a 2 M ethanol + 2 M KOH solution. For the 60 °C, the maximum power density of composite membrane achieved was 11.4 mW cm⁻².