Chemical stability of proton exchange membranes synergistically promoted by organic antioxidant and inorganic radical scavengers

The synergistic effects between organic antioxidants with metal ion chelation ability and inorganic radical scavengers were investigated. The different perfluorosulfonic acid (PFSA) composite membranes were prepared by single doping and codoping of alizarin (AZR) and cerium ions. AZR and cerium ion codoping not only significantly enhanced the oxidative stability of the membrane but also lessened both the migration of cerium ions from the membrane and the ionic cross-linkages of cerium ions with sulfonic acid groups. AZR/Ce codoping of the PFSA composite membrane exhibited a maximum power density of 966 mW cm −2 at 75 °C under 80% RH, which was 89.45% of that of the pristine PFSA membrane, whereas only 79.37% remained for cerium ion single doping of the membrane under the same conditions. The AZR/Ce-codoped PFSA composite membrane released much less fluoride than the single-doped PFSA, AZR, or cerium ion composite membranes. The antioxidation effects of AZR/Ce codoping of the PFSA composite membrane were also studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical hydrogen crossover analysis, and cell performance analysis. Notably, the open-circuit voltage (OCV) test indicated that the AZR/Ce-codoped PFSA composite membrane was still viable after 456 h of testing, whereas the other membranes were seriously damaged. • Promote chemical stability of the membrane by co-doping organic antioxidant and inorganic radical scavenger. • Synergy effects of alizarin and cerium ions on scavenging free radicals. • About 89.45% of the original power density is retained after co-doping alizarin and cerium ions. • PFSA/AZR4/Ce2 composite membrane is still very alive after 456h OCV test.