▎ 摘　　要

Promising proton exchange membranes comprising a nitrogen-rich and a high molecular weight poly[2,2'-(bipyridyl)-bibenzimidazole] (BipyPBI) polymer as a substrate and graphene oxide (GO) as a filler were successfully fabricated. The synergism of GO on the membrane physicochemical properties, including the acid doping level, acid retention capability, water uptake, swelling degree, mechanical properties, proton conductivity, oxidative stability, and the hydrogen permeability was studied. The results of the study confirmed the fabrication of mechanically robust and highly conductive proton exchange membranes. Regarding the phosphoric acid (PA) doping level, the BipyPBI/GO membrane reached 17 mol of PA per monomeric unit of BipyPBI (an increase of around 69% in PA-doping level compared to the bare BipyPBI membrane). The proton conductivity at 60 degrees C under anhydrous conditions increased from 0.002 S cm(-1) to 0.019 S cm(-1) (around 10-folds increase) when 4 wt% of GO was incorporated into the BipyPBI matrix. In addition, the conductivity reached 0.045 S cm(-1) at 140 degrees C. The activation energy of the proton conduction decreased from 45.6 kJ mol(-1) for the bare BiPyPBI to 12 kJ mol(-1) for the composite membranes, indicating an improved proton mobility where the GO worked as a carrier-bridge for a smooth proton transfer into the polymer matrix. Furthermore, the H-2 permeability reached 1.3 Barrer at 140 degrees C, indicating the fabrication of tightly-packed membranes. These results provide a very promising membrane for fuel cell applications.