两性离子聚合物功能化电极用于电容去离子的增强的电化学稳定性,ACS Applied Materials & Interfaces

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两性离子聚合物功能化电极用于电容去离子的增强的电化学稳定性
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2018-02-12 00:00:00 , DOI: 10.1021/acsami.7b14609
Youngsuk Jung ₁ , Yooseong Yang ₂ , Taeyoon Kim ₃ , Hyun Suk Shin ₃ , Sunghoon Hong ₃ , Sungmin Cha ₄ , Soonchul Kwon ₃

Affiliation

在电容去离子中，电极的盐吸附能力对于微咸水的有效软化至关重要。为了提高水的去离子能力，碳电极表面用离子交换树脂改性。在这里，我们介绍了两性离子聚合物在活性炭上的包封，以提供一种在电化学性能期间稳定电极结构并增强电容去离子效率的阻隔层。与传统的活性炭相比，表面改性的活性炭具有显着增强的电容去离子性能，盐吸附能力约为2.0×10 ^–4mg / mL，在碱金属离子溶液中的最小电导率为〜43μS/ cm。封装活性炭表面增加了离子吸附位点的数量和电极的表面积，从而改善了电荷分离和去离子效率。另外，涂层抑制了电极和电解质之间的副反应，从而提供了稳定的循环性。我们的实验结果表明，分布均匀的涂层对增强的电化学性能产生协同作用。另外，密度泛函理论计算表明，碱金属离子与两性离子聚合物之间存在良好的结合亲和力，这支持了优选的盐离子吸附在涂层上。

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Enhanced Electrochemical Stability of a Zwitterionic-Polymer-Functionalized Electrode for Capacitive Deionization

In capacitive deionization, the salt-adsorption capacity of the electrode is critical for the efficient softening of brackish water. To improve the water-deionization capacity, the carbon electrode surface is modified with ion-exchange resins. Herein, we introduce the encapsulation of zwitterionic polymers over activated carbon to provide a resistant barrier that stabilizes the structure of electrode during electrochemical performance and enhances the capacitive deionization efficiency. Compared to conventional activated carbon, the surface-modified activated carbon exhibits significantly enhanced capacitive deionization, with a salt adsorption capacity of ∼2.0 × 10^–4 mg/mL and a minimum conductivity of ∼43 μS/cm in the alkali-metal ions solution. Encapsulating the activated-carbon surface increased the number of ions adsorption sites and the surface area of the electrode, which improved the charge separation and deionization efficiency. In addition, the coating layer suppresses side reactions between the electrode and electrolyte, thus providing a stable cyclability. Our experimental findings suggest that the well-distributed coating layer leads to a synergistic effect on the enhanced electrochemical performance. In addition, density functional theory calculation reveals that a favorable binding affinity exists between the alkali-metal ion and zwitterionic polymer, which supports the preferable salt ions adsorption on the coating layer. The results provide useful information for designing more efficient capacitive-deionization electrodes that require high electrochemical stability.

更新日期：2018-02-12

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