Transfer-free in-situ synthesis of high-performance polybenzimidazole grafted graphene oxide-based proton exchange membrane for high-temperature proton exchange membrane fuel cells

The preparation of traditional graphene oxide (GO)-based proton exchange membrane (PEM) composites asks for multiple transfer steps due to the different solvent requirements of GO preparation and polymer synthesis . Moreover, GO is easy to agglomerate in polymer matrix , it is difficult to give full play to the excellent proton conductivity of single/few-layered nanosheets . Herein, a novel transfer-free in-situ method is developed to prepare poly(2,5-benzimidazole) (ABPBI)-grafted electrolytic graphene oxide (EGO) composites (ABPBI-EGO) for high-temperature (HT) PEM fuel cells applications . The process involves the in-situ electrochemical oxidation and exfoliation of graphite foil into single/few-layered EGO in Eaton's reagent and followed by in-situ synthesis of ABPBI-grafted-EGO composites in the same reagent. This strategy leads to a single or few-layered dispersion of EGO nanosheets in ABPBI matrix, thus significantly improving the physicochemical performance. By constructing fast proton-conducting channels through single/few-layered GO nanosheets , composite membranes without free phosphoric acid exhibit superior proton conductivities over the whole temperature range of 120–180 °C. ABPBI-0.5EGO composite membrane-based fuel cell achieves a power density of 349 mW/cm 2 at 180 °C, which is nearly 2.3 times higher than the original ABPBI membrane. Thus, this transfer-free in-situ strategy shows great promise for developing high-performance HT-PEMs.