Recent Progress in Pyridinyl-Based Ion Exchange Membranes for Sustainable Energy Applications

Polymer-electrolyte membrane fuel cells (PEMFCs) deliver high efficiencies and leading power densities, making them a promising cornerstone technology for decarbonization across transportation, stationary power, and emerging distributed energy systems. The ion exchange membrane (IEM) dictates proton transport, governs water and gas management, and eventually constrains durability and feasibility. Although perfluorosulfonic acid membranes have long defined the state-of-the-art, their environmental footprint, supply-chain limitations, and intrinsic performance trade-offs have intensified efforts to develop sustainable, high-performance alternatives. Among the most compelling candidates to emerge are pyridinyl-based IEMs, a rapidly expanding materials family distinguished by exceptional oxidative and hydrolytic stability, versatile molecular design, and competitive ionic conductivity. This review critically evaluates progress across the diverse landscape of pyridinyl-based IEMs, including pyridinyl- and pyridinium-functionalized hydrocarbon backbones, and hybrid architectures and discusses how molecular design principles translate into macroscopic transport properties and cell performance. We further outline the growing relevance of these materials beyond PEMFCs, highlighting their integration into electrochemical and separation platforms. Finally, we identify the key scientific and engineering challenges that remain, ranging from achieving long-term chemical durability under realistic operating conditions to scaling synthetic routes and integrating membranes into commercial architectures, and propose research directions to accelerate the maturation of pyridinyl-based IEMs.