等离子体辅助制备炭布负载大层间距NiCoAl-LDHs及其电化学去离子性能

Plasma-assisted preparation of NiCoAl-layered double hydroxides with a large interlayer spacing on carbon cloth for electrochemical deionization

  • 摘要: 电容去离子技术近年来被认为是一种新兴的海水淡化技术,尤其在苦咸水范围内具有经济节能的特点。然而,目前关于除氯电极的研究较少,同时缓慢的除盐动力学也制约了除氯电极的发展。本工作通过在表面酸处理后的柔性炭布(ACC)上原位生长层状氢氧化物NiCoAl-LDHs纳米片阵列并进行Ar等离子体处理,制备了具有扩大层间距的Ar-NiCoAl-LDHs@ACC材料。炭布基底抑制了NiCoAl-LDHs纳米片的团聚并提高了电导率,Ar等离子体处理则进一步扩大了NiCoAl-LDHs层间距并改善了亲水性,提供了快速的氯离子扩散通道,并释放了更多的层间活性位点,实现了高除盐动力学。将Ar-NiCoAl-LDHs@ACC作为除氯电极与活性炭组装了混合式电容去离子器件。在1000 mg L−1 NaCl溶液及1.2 V工作电压下,除盐容量可达到93.26 mg g−1,除盐速率可达到0.27 mg g−1 s−1,电荷效率高达0.97。在300 mg L−1 NaCl溶液及0.8 V工作电压下,经100次循环后容量保持率仍在85%以上。本工作的制备策略为大层间距二维金属氢氧化物材料的可控制备和高性能电化学除氯电极的设计构建提供了新思路。

     

    Abstract: Capacitive deionization has been considered an emerging desalination technique in recent years, especially for its economic and energy-saving characteristics for brackish water. However, there are currently few studies on chloride ion removal electrodes, and the slow desalination kinetics limits their development. Ar-NiCoAl-layered double hydroxide (LDHs)@ACC materials with an increased interlayer spacing were prepared by the in-situ growth of NiCoAl-LDHs nanosheet arrays on acid-treated carbon cloth (ACC) and subsequent argon plasma treatment. The carbon cloth suppresses the agglomeration of the NiCoAl-LDHs nanosheets and improves the electrical conductivity, while the plasma treatment increases the interlayer spacing of NiCoAl-LDHs and improves its hydrophilicity. This provides rapid diffusion channels and more interlayer active sites for chloride ions, achieving high desalination kinetics. A hybrid capacitive deionization (HCDI) cell was assembled using Ar-NiCoAl-LDHs@ACC as the chloride ion removal electrode and activated carbon as the sodium ion removal electrode. This HCDI cell achieved a high desalination capacity of 93.26 mg g1 at 1.2 V in a 1 000 mg L1 NaCl solution, a remarkable desalination rate of 0.27 mg g1 s1, and a good charge efficiency of 0.97. The capacity retention remained above 85% after 100 cycles in a 300 mg L1 NaCl solution at 0.8 V. The work provides new ideas for the controlled preparation of two-dimensional metal hydroxide materials with a large interlayer spacing and the design of high-performance electrochemical chlorine ion removal electrodes.

     

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