Composite Proton Exchange Membranes with Interlayer Structure Containing Functional Catalyst Particles for Water Electrolysis

The development of more cost-effective and efficient proton exchange membrane (PEM) water electrolysis cells requires the use of thinner membranes with extended lifetimes and reduced gas crossover. One approach to address these challenges involves the incorporation of radical scavengers to mitigate radical-induced ionomer degradation and gas recombination catalysts to promote the conversion of crossover hydrogen and oxygen to water. The positioning effects of these two catalyst interlayers in composite membranes were investigated. Results reveal that placing a Ce_0.5Zr_0.5O₂ radical scavenger interlayer near the cathode notably reduces the ionomer degradation rate, compared to its placement near the anode. The Ce content in cerium-zirconium oxide was optimized, with Ce_0.25Zr_0.75O₂ demonstrating the highest radical scavenging activity. The Pt gas recombination interlayer is confirmed to be more effective when positioned near the anode. This Pt interlayer, however, was found to induce additional ionomer degradation and was replaced by a bi-functional catalyst interlayer of Pt/Ce_0.25Zr_0.75O₂. Consequently, the composite membrane with a Ce_0.25Zr_0.75O₂ interlayer near the cathode and a Pt/Ce_0.25Zr_0.75O₂ interlayer near the anode yields the lowest rates of both ionomer degradation and hydrogen crossover, demonstrating a projected membrane lifetime 7.4 times longer and a H₂ in O₂% 4.4 times lower compared to the blank membrane.