Reconfiguring the Proton Transport Channels in Proton Exchange Membranes via Phytic Acid-Functionalized Graphene Oxide for Enhanced Performance

Abstract

Precise regulation of the hydrophilic channels within perfluorosulfonic acid (PFSA) proton exchange membranes is critical for their performance. Here, we present a high-performance composite membrane in which phytic acid-functionalized graphene oxide (PhyGO) is introduced into the PFSA matrix to reconfigure the hydrophilic channels. At an optimal loading of 1 wt %, PhyGO nanosheets are well-dispersed in the PFSA matrix, and their phosphate groups establish an additional hydrogen-bonding network. This network bridges and reconfigures the original hydrophilic channels into more continuous pathways for proton transport. Consequently, the composite membranes exhibit enhanced proton conductivity (1.23 times at 80 °C), improved dimensional stability (0.94 times at 80 °C), suppressed hydrogen crossover (0.91 times), and increased power density (1.21 times) compared to pristine PFSA membranes. Furthermore, the composite membrane also demonstrates superior chemical durability, which is attributed to the combined hydrogen-barrier effect and radical-quenching ability of PhyGO nanosheets. In contrast, excessive PhyGO loading leads to severe filler aggregation, disrupting the continuity of proton transport channels and mechanical integrity, thus degrading the overall performance. This work demonstrates that employing functionalized 2D nanomaterials to reconstruct the hydrophilic proton-conducting pathways is an effective strategy for developing high-performance composite membranes.