High-temperature proton exchange membrane systems (HT-PEM) based on polybenzimidazole (PBI) membranes are a promising technology offering significant advantages over their low-temperature counterparts. A key challenge limiting its long-term durability is the leaching of phosphoric acid (PA) from the membrane during operation. This work introduces, for the first time, the strategy of modifying polybenzimidazole (PBI) membranes with amino-functionalized porous aromatic frameworks (PAF-20-NH₂) to fundamentally enhance their PA retention and operational stability, a critical challenge for high-temperature PEM technologies. We propose that the synergistic combination of the framework’s nanoscale porosity and the specific interaction of its amino groups create an unprecedented network for acid immobilization via reinforced hydrogen bonding. A comprehensive study of the membranes’ physicochemical and structural properties reveals that PAF-20-NH₂ modification results in a significant and quantitatively demonstrated improvement in acid retention capacity, directly translating into a notable increase in proton conductivity compared to both pristine PBI and membranes modified with the non-functionalized PAF-20. These findings establish a new, highly effective pathway for the rational design of next-generation high-performance PBI-based membranes.

Proton exchange membrane fuel cells (PEMFCs) are a promising technology for electric transport; however, their anode and cathode electrocatalysts are susceptible to poisoning by airborne impurities (CO, NOx, SO2, H2S) in urban environments. In this review, modification strategies aimed at enhancing poison tolerance while preserving the electrochemically active surface area and activity are organized according to the dominant protective mechanism, namely: electronic modulation of Pt via heteroatom incorporation, alloying, or strong metal-support interaction (SMSI) effects; bifunctional and cocatalytic pathways enabled by transition metal oxides; geometric and physical blocking through core-shell architectures and barrier layers; and synergistic multicomponent systems that integrate several of these mechanisms. The SMSI effect is demonstrated to be pivotal in weakening the bond between Pt active sites and impurity intermediates. Multicomponent systems combining an oxophilic component with an electrically conductive additive have been shown to provide the optimal balance between stability, activity, and the conversion rate of catalytic poisons at typical PEMFC operating temperatures.

The thermal stability of proton exchange membranes is one of the crucial aspects that should be considered during the optimization, design, and formulation of proton exchange membrane fuel cells (PEMFCs) adapted to varying and high temperatures. In this work, the effect of thermal cycling in the temperature range of 25–150 ℃ on the structural and transport properties of pristine and SiO2-modified (5 wt.%) Nafion® solution-cast membranes was investigated. Thermogravimetric analysis and impedance spectroscopy revealed that the incorporation of pre-formed nanoparticles leads to a decrease in thermal stability and does not prevent the degradation of proton conductivity, which declines by 85% after 120 heating-cooling cycles. Fourier-transform infrared spectroscopy during thermal cycling identified chemical degradation of the polymer chains for both membrane samples. Quantitative analysis of small-angle X-ray scattering data established that the degradation of transport properties is caused by an irreversible restructuring of the membranes. A decrease in the size of ionic domains and in the mean distance between neighboring domains was observed, indicating fragmentation of ionic clusters during thermal cycling and a reduction in their connectivity while the overall water uptake capacity of the samples was preserved. The obtained results demonstrate that membrane modification by the incorporation of pre-formed SiO2 nanoparticles does not ensure stabilization of the ionomer nanostructure, pointing to the need to adopt alternative modification approaches.

In this work, a multicomponent platinum electrocatalyst supported on carbon (Pt^X/(Sb^Y + SnO₂^Z)/C) was synthesized for the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) for a proton exchange membrane fuel cell (PEMFC). Specific surface area analysis and scanning electron microscopy studies confirmed the incorporation of antimony and tin dioxide nanoparticles into the electrocatalyst structure. Electrochemical studies made it possible to differentiate the contribution of the modifiers to the characteristics of the modified electrocatalyst. Due to the incorporation of tin dioxide, the specific activity values in the oxygen reduction and methanol oxidation reactions exceed those of the unmodified samples by 40 and 36%, respectively. The introduction of antimony contributed to the retention of high electrochemical characteristics (20% less loss of active surface area) upon exposure to catalytic poisons by increasing electrical conductivity. The multicomponent electrocatalyst is also characterized by a 2.8-fold increase in stability and an electrochemically active surface area comparable to that of a commercial sample.