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

Abstract

Here, we present a series of organic-inorganic composite membranes using graphitic carbon nitride (gC 3 N 4 ) derivatives (porous (p-) gC 3 N 4 ) and F-doped porous (F-p-) gC 3 N 4 ) to improve the electrochemical properties and dimensional stability for anion exchange membranes (AEMs). The introduction of F-p-gC 3 N 4 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, H 2 -O 2 fuel cell performance of QPPO/F-p-gC 3 N 4 -0.5 reached a maximum peak power density of 286.2 mW cm −2 at 60 °C. In addition, the QPPO/F-p-gC 3 N 4 -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. • The F-doped porous gC 3 N 4 (F-p-gC 3 N 4 ) was prepared for anion exchange composite membranes. • The composite membrane showed superior ion conductivity of 142.1 mS cm −1 with suitable dimensional stability. • The ion conductivity of composite membrane was well-retained after alkaline stability >30 days in 1 M KOH at 80 °C. • The H 2 -O 2 fuel cell performance exhibited the highest peak power density of 286.2 mW cm −2 . • The prepared composite membrane exhibited long-term stability at 60 °C for 100 h.