A novel polybenzimidazole composite modified by sulfonated graphene oxide for high temperature proton exchange membrane fuel cells in anhydrous atmosphere

A novel functional graphene with high ion exchange capacity (IEC) was prepared by grafting reaction induced by 60Co γ‐ray irradiation using graphene oxide. Then, polybenzimidazole/radiation grafting graphene oxide (PBI/RGO) composite membranes were prepared by the solution‐casting method and doped with phosphoric acid (PA) to improve their proton conductivity. The properties of PBI/GO/PA and PBI/RGO/PA membranes including the PA doping level, chemical stability, proton conductivity and mechanical properties were evaluated and compared. The tensile strength of PBI/RGO/PA membranes (ranging from 27.3 to 38.5 MPa) increases at first and then decreases with the increase of the RGO content, and is significantly higher than that of other PA doped PBI‐based membranes. The proton conductivity of PBI/RGO‐3/PA membrane is 28.0 mS cm−1 at 170 °C without humidity, with an increase of 72.0% compared with that of PBI/PA membrane. These results suggest that PBI/RGO/PA membranes have the potential to be used as high‐temperature proton exchange membranes.