Synthesis of Nafion/CeO2 hybrid for chemically durable proton exchange membrane of fuel cell

• Published in: Journal of membrane science 2012-12, Vol.421-422, p.201-210
• Main Authors: Wang, Zhao, Tang, Haolin, Zhang, Huijie, Lei, Ming, Chen, Rui, Xiao, Pan, Pan, Mu
• Format: Article
• Language: English
• Subjects: artificial membranes; ceric oxide; Chemical durability; corrosion; dimensional stability; durability; electrolytes; ferrous chloride; fuel cells; hydrogen peroxide; hydroxyl radicals; nanoparticles; PEM fuel cell; Proton exchange membrane; Radical scavenge; Self-assembly; sol-gel processing
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2012.07.014

Nafion/CeO2 hybrid composites prepared through a self-assemble route are proposed for chemically durable electrolyte membrane of fuel cell. Self-assembly of Nafion and CeO2 nanoparticles between the positively charged CeO2 and the negatively charged SO3− end groups of Nafion ionomers gives the composite structure a good compatibility on the interface. As a result, the Nafion/CeO2 hybrid proton exchange membranes present conductivities slightly lower than that of the pristine Nafion membrane at 100RH% condition, whereas much higher than the later when humidification is below 75RH%. The Nafion/CeO2 hybrid membranes also display excellent radical scavenge ability under hydroxyl radical corrosion condition. With Fenton reagent of 30wt% H2O2 solution containing 20ppm FeCl2 at 85°C, the fluoride emission rates for the self-assembled Nafion/CeO2 membranes with ceria content of 1, 3, 5, 10wt% are 43.05, 8.67, 6.01, 4.47mgh−1, respectively, much lower than that for pristine Nafion membrane (55.78mgh−1) and Nafion/CeO2 membrane prepared from the conventional sol–gel method (11.64mgh−1). Another important aspect of the self-assembled Nafion/CeO2 membrane contributed to the durability is the low humidity-induced stress and dimensional stability. The humidity-induced stress of the self-assembled Nafion/CeO2 membranes with ceria content of 1–10wt% was 1.22–1.93MPa, in comparison to 2.25MPa of pristine Nafion membrane. Thus, the proton exchange membranes prepared from self-assembled Nafion/CeO2 present high durability under the fuel cell operating conditions. In the open circuit voltage accelerated test under in situ accelerating RH cyclic test, the OCV reduction rate of self-assembled Nafion/CeO2 membrane with ceria content of 5wt% is 1.13×10−4mV/s, much lower than 11.7×10−4mV/s of the pristine Nafion membrane and 5.78×10−4mV/s of the Nafion/CeO2 hybrid membrane prepared from the conventional sol–gel method. Nafion/CeO2 nanocomposites through a self-assemble route are proposed for chemically durable electrolyte membrane of fuel cell. The nanoelectrolyte membranes display excellent radical resistance ability because of the radical scavenge of well-dispersed ceria due to the electrostatic self-assembly between the positively charged CeO2 and the negatively charged SO3− end groups of Nafion ionomers [Display omitted] . ► Chemically durable proton exchange membrane. ► Radical scavenge of Nafion/CeO2 nanocomposites. ► Low humidity-induced stress and water retention.