THE EFFECT OF TITANIUM DIOXIDE FILLER IN POLYBENZIMIDAZOLE-SULFONATED GRAPHENE OXIDE COMPOSITE MEMBRANE FOR HIGH- TEMPERATURE PEMFC APPLICATIONS

The polybenzimidazole (PBI) membrane shows significant potential as an alternative membrane for high-temperature PEMFC. However, PBI membranes exhibit low proton conductivities under low humidity conditions and have drawbacks related to acid leaking and phosphoric acid degradation over 160 degrees C. Notably, metal oxide particles exhibit a strong affinity for phosphoric acid. Therefore, titanium dioxide (TiO2) was introduced to investigate its impact on self -humidified PBI-SGO membrane at different mass ratios, utilizing a sonication technique. The hygroscopic properties of TiO2 on PBI-SGO composite membranes are tested for proton conductivity at varied temperatures (25-150 degrees C), acid doping levels, as well as ion exchange capacity to evaluate their potential as an electrolyte for high-temperature PEMFC application. The PBI-SGO-TiO2 with the mass ratio of 2:1.5 exhibited the highest proton conductivity (0.0128 S cm-1 at 25 degrees C and 0.0207 S cm-1 at 150 degrees C) and achieves a higher level of acid doping level and ion exchange capacity with a value of 10.23 ADL and 1.72 mmol g-1, respectively. The composite membranes are also physically characterized by using FTIR, XRD, and FESEM. The PBI-SGO-TiO2 (2:1.5) displayed a good distribution of TiO2 powder, thus contributing to the maximum proton conductivity value. The results of the study prove that the PBI-SGO-TiO2 composite membrane is a potential membrane for applications in HT-PEMFC.