Phosphoric acid doped composite membranes from poly (2,5-benzimidazole) (ABPBI) and CsxH3−xPW12O40/CeO2 for the high temperature PEMFC

Poly (2,5-benzimidazole) (ABPBI) was prepared from 3,4-diaminobenzoic acid via a polymerization reaction. This benzimidazole polymer has a good thermal stability at the desired temperatures of 140–200 °C. The membranes of ABPBI are readily to be doped with phosphoric acid at room temperature show very promising proton conductivity. A multifunctional catalyst CsxH3−xPW12O40/CeO2 was prepared to mitigate the free radical attack to improve the chemical stability in fuel cell environment. CsxH3−xPW12O40/CeO2 nanoparticles synthesized by solution-based hydrothermal method and two-step impregnation method were dispersed uniformly into the resin, and then the composite membrane was prepared using solution-cast method. The particles prepared were characterized by X-ray powder diffraction (XRD) and SEM evaluates the crystallite size, distribution of the nanoparticles and the crystal structure. The chemical stability of membrane was investigated via ex situ Fenton test. In the durability tests, the weight loss rate (WLR) reduced 75% by adding CsxH3−xPW12O40/CeO2 nanoparticles into the ABPBI membrane, besides, it could improve proton conductivity up to 0.2 S cm−1 in a temperature range of 140–180 °C under different relative humidity. The power density of the cell with the composite membrane was up to 530 mW cm−2.