沸石咪唑酯骨架-8衍生氮掺雜孔洞碳材之改質在高效電容去離子化上的應用

Modification of ZIF-8 Derived, N-doped Porous Carbon Electrodes for High Performance Capacitive Deionization

李洋(Yang Li)

指導教授 ： 吳嘉文

國立臺灣大學/工學院/化學工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201701098

摘要

水作為生命之源,在人們的生活中扮演著必不可少的角色。然而,隨著人口數目的增長以及工農業活動的擴張，水資源短缺成為了21世紀最嚴峻的問題。由于地球上絕大部分的水都是鹽水，無法被人類生產生活直接使用，因此脫鹽技術作為生產淡水的方法具有非常廣闊的應用前景。電容去離子化，也被稱為電吸附，因其可以對低濃度的鹽水進行有效的脫鹽，並且成本很低而受到了廣泛的關注。
首先，我們採用在溫度分別為600,800以及900 °C的條件下，碳化沸石咪唑酯骨架-8來製備孔洞碳材料。在這三種樣品當中，NC800電極具有最大的比表面積（975.40 m2/g）以及最大的微孔體積（0.14 cm3/g）。我們並沒有否認以此方式製備的孔洞碳材作為CDI電極的效用，但是在此種氮摻雜孔洞碳材中仍然存在一些嚴重的問題（例如：導電度差，孔的尺寸狹小，孔體積比較小等），將會影響它們作為CDI電極的表現。
為了解決上述問題，我們想到兩種方法提升氮掺雜孔洞碳材的導電性。首先，我們將金奈米顆粒嵌入到沸石咪唑酯骨架-8當中，隨後再將此物質碳化。第二種方法當中，由於PEDOT是一種導電高分子，具有良好的導電性，因此我們將NC800顆粒與PEDOT奈米管結合在一起製備一種新的孔洞電極材料以提升CDI表現。NC800-PEDOT具有非常優異的電吸附表現，在濃度為1 mM的氯化鈉溶液中，其電吸附容量可以達到16.18 mg/g,高於NC800 (8.36 mg/g)和Au@NC800 (14.31 mg/g)。總的來說，由於NC800-PEDOT和Au@NC800能夠顯著提升NC800的導電性，NC800-PEDOT和Au@NC800作為CDI的電極材料使用具有非常好的應用前景。

關鍵字

電容去離子化 ； 沸石咪唑酯骨架-8 ； 氮掺雜 ； Au@NC800 ； NC800-PEDOT

並列摘要

Water is the source of life and the lifeblood of human survival and development. Nevertheless, the rapid population growth coupled with the expansion of industrial and agricultural activities, caused water shortages the most serious problem to humanity in the 21st century. The desalination of sea or brackish water is a promising approach to generate fresh water because most of earth’s water is saline water, which is not suitable for direct consumption. Capacitive deionization (CDI), also known as electrosorption, is emerging as a separation technology for removing salt ions and ionic species from aqueous solutions using an electrosorption process due to its less energy consumption and environmental friendliness compared to traditional desalination technologies.
We firstly prepared the nitrogen-doped porous carbon particles by carbonizing zeolitic imidazolate framework (ZIF-8) at 600, 800 and 900 °C. Among these three samples, NC800 electrode exhibits the largest specific surface area and micropore volume of 975.40 m2/g and 0.14 cm3/g. There is no denying the fact that such resultant porous carbon particles should be an ideal electrode material for CDI application. However, some serious issues (e.g. low electrical conductivity, narrow pore size, relatively low pore volume, etc.) still remain in the nitrogen-doped porous carbon particles, which harm their CDI performance. In order to solve the above-mentioned problems, we herein report the de novo synthesis of metal-nanoparticle-embedded zeolitic imidazolate frameworks (ZIF-8) with gold ions introduced inside ZIF-8 upon the formation of ZIF-8 in aqueous solutions. The gold-nanoparticle-embedded ZIF-8 (Au@ZIF-8) was then carbonized into a nitrogen-containing porous carbon (Au@NC).
PEDOT is a transparent conducting polymer based on 3,4-ethylenedioxythiophene or EDOT monomer. We also combine NC800 powder and PEDOT NTs together to create a new generation of porous electrode for highly efficient capacitive deionization. NC800-PEDOT achieves an excellent electrosorption performance with a high electrosorption capacity of 16.18 mg/g when the initial NaCl concentration is 1 mM, higher than those of NC800 (8.36 mg/g) and Au@NC800 (14.31 mg/g). All in all, NC800-PEDOT and Au@NC800 should be promisingly applicable as highly efficient CDI electrode materials since they have notably increased the conductivity of parent NC800.

並列關鍵字

capacitive deionization ； ZIF-8 ； nitrogen doping ； Au@NC800 ； NC800-PEDOT

參考文獻

[1] Y. Liu, X.T. Xu, M. Wang, T. Lu, Z. Sun, L.K. Pan, Metal-organic framework-derived porous carbon polyhedra for highly efficient capacitive deionization, Chemical Communications, 51 (2015) 12020-12023.

[3] R. Semiat, Energy issues in desalination processes, Environmental Science & Technology, 42 (2008) 8193-8201.

[4] Y.H. Liu, H.C. Hsi, K.C. Li, C.H. Hou, Electrodeposited manganese dioxide/activated carbon composite as a high-performance electrode material for capacitive deionization, Acs Sustainable Chemistry & Engineering, 4 (2016) 4762-4770.

[5] Z. Wang, T.T. Yan, J.H. Fang, L.Y. Shi, D.S. Zhang, Nitrogen-doped porous carbon derived from a bimetallic metal-organic framework as highly efficient electrodes for flow-through deionization capacitors, J. Mater. Chem. A, 4 (2016) 10858-10868.

[6] S. Porada, R. Zhao, A. Van Der Wal, V. Presser, P.M. Biesheuvel, Review on the science and technology of water desalination by capacitive deionization, Progress in Materials Science, 58 (2013) 1388-1442.