Preparation and performance study of SPEEK/S-GO/NH2–SiO2/PPS composite proton exchange membrane based on acid–base cooperative topological conductive network

This study uses polyphenylene sulfide (PPS) fiber paper as a skeletal support to fabricate a high-density, porous nonwoven support layer with excellent mechanical stability via wet papermaking. Sulfonated polyether ether ketone (SPEEK) is then cast onto its surface to form a continuous proton-conducting phase. Building on this foundation, synergistic doping with sulfonated graphene oxide (S-GO) and amino-modified silica (NH 2 –SiO 2 ) constructs a topologically interconnected proton exchange membrane structure exhibiting acid-base synergistic effects. The sulfonic acid groups on the S-GO surface act as high-density proton donors, providing continuous proton conduction sites. Meanwhile, the basic amino groups in NH 2 –SiO 2 form stable acid-base interactions and hydrogen-bond networks with sulfonic acids, effectively anchoring proton migration pathways, reducing disordered swelling, and extending proton hopping distances. This topologically interconnected acid-base synergistic network significantly enhances proton transport dominated by the Grotthuss mechanism while effectively suppressing methanol permeation. Performance testing reveals that the composite membrane with optimized doping ratio achieves proton conductivity up to 0.2 S cm −1 at 80 °C, with methanol permeability significantly lower than commercial Nafion-117 membranes. In direct methanol fuel cell testing, the composite membrane exhibited an open-circuit voltage of approximately 770 mV and a peak power density approaching 170 mW cm −2 , while demonstrating excellent thermal stability, oxidation resistance, and mechanical strength. These results demonstrate that constructing a topologically interconnected structure with synergistic acid-base interactions can effectively balance proton conductivity and fuel barrier performance, providing a viable new strategy for developing high-performance, low-cost proton exchange membrane materials.