Peptide-Modified Electrode Surfaces for Promoting Anion Exchange Ionomer Microphase Separation and Ionic Conductivity

Ionomer binders are critical materials for delivering ions to and from electrocatalyst surfaces in fuel cell and water electrolyzer technologies. Most studies examine these materials as bulk polymer electrolyte membranes, and comparatively little attention has been given to their behavior on electrode surfaces as thin films. This report demonstrates that sequence-defined peptides anchored to electrode surfaces, or the solvent vapor annealing processing, alters the microstructure configuration of anion exchange ionomers (AEIs). It is observed that moderately sized microphase-separated ionic domains of the AEI, obtained either by peptide-modified electrodes or solvent vapor annealing, give rise to a two- to three-fold increase in thin-film in-plane ionic conductivity. Interestingly, the use of peptide-modified electrodes, in conjunction with solvent vapor annealing, yields excessively large ionic grains that compromise ionic conductivity. Overall, the judicious use of sequence-defined peptides adsorbed to electrode surfaces, or solvent vapor annealing, encourage the appropriate microstructures of thin-film AEIs resulting in ameliorated ionic conductivity.

离聚物粘结剂（Ionomer binder）是燃料电池与水电解槽技术中，实现离子在电催化剂表面双向传输的关键材料。现有研究多将此类材料作为本体聚合物电解质膜开展探究，而针对其以薄膜形式在电极表面的行为的关注相对不足。本研究表明，锚定在电极表面的序列定制肽（sequence-defined peptides）或是溶剂蒸气退火工艺，均可改变阴离子交换离聚物（Anion Exchange Ionomers, AEIs）的微观结构构型。研究发现，通过肽修饰电极或溶剂蒸气退火工艺制备的阴离子交换离聚物，其适度尺寸的微相分离离子域可使薄膜面内离子电导率提升2至3倍。值得注意的是，若同时采用肽修饰电极与溶剂蒸气退火工艺，则会生成尺寸过大的离子晶粒，反而削弱离子电导率。综上，合理使用吸附于电极表面的序列定制肽或是采用溶剂蒸气退火工艺，可促使薄膜态阴离子交换离聚物形成适宜的微观结构，从而改善其离子电导率。