フレームワーク材料におけるポリアニリン媒介による水分遮断と活性部位増強を通じた二価イオン抽出の促進

Framework materials offer abundant ion-intercalation sites; however, their desalination performance is often limited by structural instability and low site utilization due to water molecule cointercalation. Herein, we employ interface engineering by coating the framework material with a compact polymer mediator layer. This approach facilitates ion transport while blocking water molecules and synergistically introduces supplementary active sites. Exemplifying this strategy, a composite material (denoted PCN) is fabricated using NiHCF (a Prussian blue analogue) and polyaniline (PANI). PCN enables efficient dual-ion (Na⁺ and Cl^-) extraction in symmetric flow-electrode capacitive deionization (FCDI) systems for seawater desalination. Mechanistic investigation reveals that the enhanced performance is not primarily attributed to improved electronic/ionic conductivity from PANI. Instead, the PANI layer forms a hydrophobic interface and introduces nitrogen sites, enabling synergistic dual-ion extraction. This compact mediator layer effectively prevents water molecule coinsertion, incorporates nitrogen-rich active sites, and ensures structural stability, thereby enhancing site utilization efficiency. This work demonstrates that modulating material interfaces to suppress H₂O-induced side reactions and augment active site availability advances electrochemical ion extraction for water purification.