The chemical stability of proton exchange membranes (PEMs) is a pivotal factor to effectuate reliable and practical durability in proton exchange membrane fuel cells (PEMFCs). Recently, we discovered unexpectedly robust chemical stability of PEMs, which was demonstrated to be attributable to the radical scavenging ability of the ferrocyanide‒ferricyanide (Fc (II)‒Fc (III)) redox cycle. In these previous studies, the Fc (II)‒Fc (III) redox species were introduced into polymer matrices using a strategy of ligand exchange, which somewhat restricts the applicable scope of available polymers. Herein, via an alternative route of physical incorporation, Fc (II)/Fc (III) species are introduced into a variety of perfluorosulfonic acid (PFSA) and sulfonated hydrocarbon PEM matrices. The resulting composite membranes display enhanced durability in PEMFC evaluations, compared with pristine membranes, even considerably beyond the composite membranes using US Department of Energy approved state-of-the-art antioxidant Ce ions. Moreover, the incorporation of Fc (II)/Fc (III) species simultaneously introduces additional proton sites after membrane acidification, thereby increasing both ex situ conductivity and in situ power output. In addition, due to hydrogen bonding between the less ionized protons on Fc (II)/Fc (III) species and the sulfonic groups of the polymer matrices, these additives show adequate retention in the composite membranes. The strategy proposed in the present work appears promising as a universal method to greatly improve the chemical oxidative stability of both PFSA and hydrocarbon-based PEMs.

质子交换膜（PEM）的化学稳定性是实现质子交换膜燃料电池（PEMFC）可靠且实用的耐用性的关键因素。最近，我们发现PEM具有出乎意料的强大化学稳定性，这被证明归因于亚铁氰化物‒铁氰化物（Fc（II）‒Fc（III））氧化还原循环的自由基清除能力。在这些先前的研究中，使用配体交换策略将Fc（II）‒Fc（III）氧化还原物质引入聚合物基质，这在一定程度上限制了可用聚合物的适用范围。本文中，通过物理掺入的替代途径，将Fc（II）/ Fc（III）物质引入各种全氟磺酸（PFSA）和磺化烃PEM基质中。与原始膜相比，所得复合膜在PEMFC评估中显示出增强的耐久性，甚至大大超出了使用美国能源部批准的最先进抗氧化剂Ce离子的复合膜。而且，Fc（II）/ Fc（III）物种的结合会在膜酸化后同时引入其他质子位点，从而增加两者异位电导率和原位功率输出。此外，由于Fc（II）/ Fc（III）物种上离子化程度较低的质子与聚合物基质的磺酸基之间的氢键结合，这些添加剂在复合膜中显示出足够的保留能力。当前工作中提出的策略有望作为一种通用方法来大大提高PFSA和烃基PEM的化学氧化稳定性。