Simultaneous improvement of anion conductivity and cell durability through the formation of dense ion clusters of F-doped graphitic carbon nitride/quaternized poly(phenylene oxide) composite membrane

Here, we present a series of organic-inorganic composite membranes using graphitic carbon nitride (gC₃N₄) derivatives (porous (p-) gC₃N₄) and F-doped porous (F-p-) gC₃N₄) to improve the electrochemical properties and dimensional stability for anion exchange membranes (AEMs). The introduction of F-p-gC₃N₄ onto a quaternized poly(phenylene oxide) (QPPO) matrix induced the expansion of the ion channel by promoting nanophase separation, and the composite membranes possess high ion conductivity (>142.1 mS cm⁻¹ at 90 °C, i.e., 1.75 times as high as the pristine membrane) and suitable alkaline durability (>74% ion conductivity in 1 M KOH at 80 °C for 30 days) with enhanced dimensional change. Importantly, H₂-O₂ fuel cell performance of QPPO/F-p-gC₃N₄-0.5 reached a maximum peak power density of 286.2 mW cm⁻² at 60 °C. In addition, the QPPO/F-p-gC₃N₄-0.5-based membrane electrode assembly can be operated under 0.15 A cm⁻² current density at 60 °C for 100 h. Thus, this strategy could be suitable for future work on AEM applications.