Ce-Metal Organic Frameworks for Enhanced Chemical Stability and Durability of Sulfonated Polyether Ether Ketone for Proton Exchange Membranes

Abstract

Proton exchange membrane fuel cells (PEMFCs) face challenges related to limited lifespan and operational reliability, hindering their commercial adoption. Sulfonated polyether ether ketone (SPEEK) has emerged as a promising alternative to Nafion due to its superior thermal stability, chemical resilience, and cost-effectiveness. SPEEK membranes were sulfonated using concentrated sulfuric acid (98%), introducing sulfonic acid (−SO₃H) groups to enhance proton conductivity. To mitigate chemical degradation while maintaining conductivity, Ce(III)-benzene dicarboxylic acid metal–organic frameworks (Ce-MOFs) were incorporated. These Ce-MOFs scavenge radicals, improving the membrane’s durability and stability. Comprehensive analysis of the physicochemical, thermal, and mechanical properties showed that Ce-MOF addition enhanced conductivity and reduced degradation. The Ce-MOF/SPEEK (1 wt%) nanocomposite membrane achieved 0.215 S/cm at 80 °C and 95% relative humidity, outperforming pristine SPEEK (0.140 S/cm). These findings highlight the potential of Ce-MOF composite PEMs as durable, high-performance materials for next-generation PEMFCs.