Precise modification of poly(aryl ether ketone sulfone) proton exchange membranes with positively charged bismuth oxide clusters for high proton conduction performance

In the field of proton exchange membranes (PEMs), it is still a great challenge to explore new Nafion alternatives, maintaining the high proton conductivity and lowering the cost of practical application. In this work, a series of low sulfonated poly(aryl ether ketone sulfone) (SPAEKS) membranes hybridized by [Bi6O5(OH)3]2(NO3)10·6H2O (H6Bi12O16) have been successfully fabricated. When the doping amount of H6Bi12O16 reaches 5 wt%, the DS15‐Bi12‐5 showing the best proton conductive ability and mechanical properties. The proton conductivity can achieve 72.8 mS·cm−1 at 80°C and the tensile strength can reach 43.57 MPa. Confirmed by experimental data and activation energy (Ea) calculations, the existence of Bi cluster makes more hydrogen bonds, providing additional proton hopping sites and offers more proton transport vehicles, leading to a high proton conduction performance. This work proved that polyoxometalates (POMs) can replace the role of sulfonate groups in SPAEKS to a certain extent and work out the defects of high sulfonation, making a remarkable contribution to the practical application of low sulfonated SPAEKS. Combining the superiority of SPAEKS and POMs, a series of POM hybrid SPAEKS membranes were synthesized. The interaction between the host and guest solves the dissolution problem of the POMs and meanwhile the existence of Bi cluster makes more hydrogen bonds, providing additional proton hopping sites and offers more proton transport vehicles, leading to a high proton conduction performance.