An effective alkaline electrolyte with magnetic field-aligned Fe3O4–GO nanofillers in a polybenzimidazole membrane for methanol fuel cells
In this work, alkaline-doped polybenzimidazole/magnetite–graphene oxide (PBI/Fe3O4–GO)
nanocomposite membranes are successfully synthesized for enhanced ion
conduction and suppressed alcohol permeation for use in direct methanol
alkaline fuel cells (DMAFCs). The structural, morphological, and magnetic properties of Fe3O4–GO nanofillers are thoroughly investigated. During the membrane drying step, the Fe3O4–GO
nanofillers are aligned in a polymeric PBI matrix using an applied
magnetic field (MF). Without an MF, the nanofillers are randomly
distributed in the PBI matrix. The composite membrane with the MF demonstrates a 2- to 3-fold increase in hydroxide conductivity (7.6 × 10−2 S cm−1) and a one-order of magnitude reduction in fuel permeability (9.96×10−7 cm2 s−1) compared to the other samples. The potassium hydroxide (KOH)-doped PBI/Fe3O4–GO composite with MF achieves a higher maximum power density (Pmax) of 226 mW cm−2 at 80 °C than the other samples. The composite membrane with an MF
demonstrates good long-term durability of 107 h with low voltage decay
(6.5 × 10−4 V h−1) at high alkaline concentrations (6 M KOH). The results indicate that a small amount (0.5 wt%) of Fe3O4–GO nanofillers has an extensive effect on membrane properties in DMAFCs.
