Anion-exchange membranes (AEMs) with high hydroxide conductivity,
strong alkaline stability, and outstanding single-cell performance
are in great demand for use in fuel cells and water electrolyzer applications.
In this study, carboxylic acid-functionalized graphene nanofibers
(c-GNF) were used as an effective filler to improve the electrochemical
and physicochemical characteristics of the commercial FAA3 for anion-exchange
membrane fuel-cell (AEMFC) application. The effects of c-GNF incorporation
on the structural, morphological, and electrochemical performances
of the composite membrane were systematically investigated. Introducing
c-GNF into the FAA3 matrix increased the electrochemical performance
and physicochemical stability of FAA3 membranes. Notably, the nanocomposite
membrane containing 1.70 wt % of c-GNF reached a maximum hydroxide
conductivity of 58.8 mS cm–1 at 90 °C, whereas
the pristine FAA3 presented only 28.7 mS cm–1. In
addition, the maximum peak power density (PPD) of 115.9 mW cm–2 was observed for the FAGNF at 1.70 wt % in a H2/O2 AEMFC at 60 °C. Moreover, the alkaline
stability test demonstrated that c-GNF inclusion had a significant
influence on membrane chemical stability by retaining the conductivity
up to 71% after 500 h of immersion in 5 M NaOH at 60 °C. Overall,
this study demonstrates the enhancement of properties of a commercial
membrane for AEMFC application.