Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
J Am Chem Soc. 2017 Aug 16;139(32):11055-11063. doi: 10.1021/jacs.7b01119. Epub 2017 Aug 4.
Materials that can selectively store Na and Cl ions in the bulk of their structures and release these ions with good cycle stability can enable the construction of a high capacity, rechargeable desalination cell for use in seawater desalination. In this study, the ability of a nanocrystalline Bi foam electrode to serve as an efficient and high capacity Cl-storage electrode using its conversion to BiOCl was investigated. When Bi as a Cl-storage electrode was coupled with NaTi(PO) as a Na-storage electrode, a new type of rechargeable desalination cell, which is charged during desalination and discharged during salination, was constructed. The resulting Bi-NaTi(PO) cell was tested under various salination and desalination conditions to investigate advantages and potential limitations of using Bi as a Cl-storage electrode. Slow Cl release kinetics of BiOCl in neutral conditions and an imbalance in Cl and Na storage (i.e., Cl storage requires three electrons/Cl, while Na storage requires one electron/Na) were identified as possible drawbacks, but strategies to address these issues were developed. On the basis of these investigations, optimum desalination and salination conditions were identified where the Bi/NaTi(PO) cell achieved a desalination/salination cycle at ±1 mA cm with a net potential input of only 0.20 V. The kinetics of Cl release from BiOCl was significantly improved by the use of an acidic solution, and therefore, a divided cell was used for the salination process. We believe that with further optimizations the Bi/BiOCl electrode will enable efficient and practical desalination applications.
材料可以选择性地在其结构主体中储存 Na 和 Cl 离子，并在良好的循环稳定性下释放这些离子，这可以实现构建一种高容量、可充电的脱盐电池，用于海水淡化。在这项研究中，研究了纳米晶 Bi 泡沫电极作为高效高容量 Cl 储存电极的能力，其通过转化为 BiOCl 来实现。当 Bi 作为 Cl 储存电极与 NaTi(PO) 作为 Na 储存电极结合时，构建了一种新型可充电脱盐电池，该电池在脱盐过程中充电，在盐化过程中放电。对所得的 Bi-NaTi(PO)电池进行了各种盐化和脱盐条件下的测试，以研究使用 Bi 作为 Cl 储存电极的优势和潜在局限性。在中性条件下 BiOCl 的缓慢 Cl 释放动力学和 Cl 和 Na 储存的不平衡（即，Cl 储存需要三个电子/Cl，而 Na 储存需要一个电子/Na）被认为是可能的缺点，但已开发出解决这些问题的策略。基于这些研究，确定了最佳的脱盐和盐化条件，在这些条件下，Bi/NaTi(PO)电池在±1 mA cm 的净电位输入仅为 0.20 V 的情况下实现了脱盐/盐化循环。通过使用酸性溶液，BiOCl 从 Bi 中的 Cl 释放动力学得到了显著改善，因此，为盐化过程使用了分置电池。我们相信，通过进一步优化，Bi/BiOCl 电极将能够实现高效且实用的脱盐应用。
