利用鐵酸鎳/還原氧化石墨烯做為高效能離子選擇性電極應用在電容去離子技術之研究

Nickel Ferrite-reduced Graphene Oxide as a High-Performance IOn Selective Electrode for Capacitive Deionization

葉北辰

指導教授 ： 張淑閔 ； 董瑞安

國立交通大學/工學院/環境工程系所/碩士(2020年)

摘要

混和金屬氧化物(Mixed transition metal oxide)為一具有高度潛力的導電材料，其擁有比單組分之金屬氧化物高之比電容能力，透過與碳材結合應用於電容去離子，並提升其脫鹽能力。
本研究利用水熱法合成鐵酸鎳(Nickel Ferrite, NiFe2O4)，並添加不同重量氧化石墨烯(GO)進行水熱法還原成還原氧化石墨烯(rGO)並與之結合，形成NiFe2O4/rGO(NFG)複合材料並應用於電容去離子技術。首先利用SEM、TEM、EDX、Raman、XRD、XPS、TGA等分析方法對NFG進行特性的鑑定，接著透過循環伏安法(CV)以及定電流充放電法(GCD)觀察其電化學表現。根據結果顯示，本研究利用水熱法所製備之rGO於1M Na2SO4電解液下電流密度為0.6 A/g時比電容值為104.9 F/g，而鐵酸鎳(NiFe2O4)之比電容值在電流密度為0.6 A/g時為27.9 F/g。此外，NFG複合材料於1M Na2SO4電解液電流密度為0.6 A/g時比電容值提升至221.0 F/g，證明兩者的結合能夠有效地提升其比電容能力，所製備之奈米複合材料將應用於電容去離子技術之電極材料。
本研究探討了不同施加電壓下(0.8 V、1.0 V、1.2 V、1.4 V)其電吸附的能力，NFG∥NFG之電吸附能力會隨著施加電壓增加而隨之上升，在1.4 V 時有著最佳SEC(salt electrosorption capacity)為29.6 mg/g，高於NFO∥NFO電極之SEC 21.5 mg/g。另外也探討了不同初始NaCl濃度(100 mg/L、200 mg/L、500 mg/、1000 mg/L)對電容去離子效率之影響，當初始濃度為1000 mg/L時SEC為28.1 mg/g，且根據Langmuir吸附模式，NFG∥NGO電極之最大SEC可達30.2 mg/g。總結來說，鐵酸鎳/還原氧化石墨烯複合材料可以有效提升電化學性能及比電容值，進而提升其電吸附能力。

關鍵字

鐵酸鎳 ； 還原氧化石墨烯 ； 電容去離子

並列摘要

Mixed transition metal oxide is a highly potential conductive material. It has a higher specific capacitance than single-component metal oxides. It can be used in capacitive deionization by combining with carbon materials and enhance its desalination ability.
In this study, Nickel ferrite (NiFe2O4) was synthesized by hydrothermal method, and graphene oxide (GO) of different weights was added and reduced to reduced graphene oxide (rGO) through hydrothermal method and combine with it to form NiFe2O4/rGO(NFG) nanocomposite and applied to capacitive deionization technology. First, we use SEM, TEM, EDX, Raman, XRD, XPS, TGA and other analytical methods to identify the characteristics of NFG, and then its electrochemical performances were evaluated through cyclic voltammetry (CV) and Galvanostatic charge/discharge (GCD). According to the results, the specific capacitance of rGO prepared by the hydrothermal method in the 1M Na2SO4 electrolyte is 104.9 F/g when the current density is 0.6 A/g, while the specific capacitance of nickel ferrite (NiFe2O4) is 27.9 F/g. In addition, the specific capacitance of the NFG composite material increases to 221.0 F/g when the current density is 0.6 A/g in 1M Na2SO4 electrolyte, which proves that the combination of the two materials can effectively improve its specific capacitance. The prepared nanocomposite material has been use in capacitive deionization technology.
This study discusses its electro-adsorption capacity under different applied voltages (0.8 V, 1.0 V, 1.2 V, 1.4 V). The electro-adsorption capacity of NFG∥NFG will increase with the increase of applied voltage. At 1.4 V, it has the best SEC (salt electrosorption capacity) is 29.6 mg/g, which is higher than the SEC of NFO∥NFO electrode of 21.5 mg/g. In addition, the influence of different initial NaCl concentrations (100 mg/L, 200 mg/L, 500 mg/, 1000 mg/L) on the deionization efficiency is also discussed. When the initial concentration is 1000 mg/L, the SEC is 28.1 mg/g, and according to the Langmuir adsorption mode, the maximum SEC of NFG∥NFG electrode can reach 30.2 mg/g. In summary, the nickel ferrite/reduced graphene oxide nanocomposite can effectively improve the electrochemical performances and specific capacitance, and then enhance its electrosorption capacity.

並列關鍵字

Nickel ferrites ； Reduced graphene oxide ； Capacitive deionization

參考文獻

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