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標題: | 尖晶石結構催化劑於電催化產氧反應之研究 Investigation of Oxygen Evolution Reaction by Spinel Materials |
作者: | Hsuan-Yu Lin 林宣佑 |
指導教授: | 陳浩銘(Hao-Ming Chen) |
關鍵字: | 水分解反應,產氧反應,尖晶石, water splitting,oxygen evolution reaction,spinel, |
出版年 : | 2016 |
學位: | 碩士 |
摘要: | 隨著環境保護的意識增長,氫氣作為一種乾淨的能量來源日益受到重視。以電化學催化水分解產氫產氧是一種生產氫氣的良好方法。然而,在整個電解系統中,產氧端產氧反應因為牽涉到四電子轉移,故其過電位 (overpotential) 往往較還原端產氫反應來的高,因此整個系統之效率會受限於氧化端。故如果針對氧化端之催化劑做優化則可以提升整體之效率。在氧化端人們常用較便宜且地球蘊含量較高的過渡元素氧化物替代較昂貴的二氧化釕及二氧化銥。其中,尖晶石結構 (spinel) 是一種兼具活性以及穩定性的材料,但過去人們對其電催化產氧反應之反應機構還不甚了解,本研究希望透過研究以鈷為基底的尖晶石結構對產氧反應之反應機構有更多的認識。
本研究中,利用共沉澱法合成一系列以鈷為基底之正結構尖晶石 (normal spinel) 催化劑,以研究在晶體結構中不同位置及價數的鈷離子對電催化產氧反應的影響。利用X光繞射儀及X光吸收光譜鑑定材料結構與金屬所在位置等基本性質,並以掃描式電子顯微鏡及穿透式電子顯微鏡觀測其形貌。電化學的量測顯示,2價鈷在整體活性上優於3價鈷且於量測時發生相變的現象。同時,透過臨場X光繞射儀發現,2價之鈷原子隨施加電壓增加會逐漸生成鈷氧氫氧化物 Co(O)OH (Cobalt Oxy-hydroxide),推測此生成物是主導尖晶石活性之關鍵。 Electrochemically catalyzed water splitting reaction is a promising green energy source. The water splitting commonly involves two reactions, including Oxygen Evolution Reaction (OER) and Hydrogen Evolution Reaction (HER). However, the OER is more sluggish than HER because four electrons are involved in OER. Recently, many researches are working on spinel materials for OER because of the both high reactivity and good long-term stability. Nevertheless, the mechanism of spinel materials toward catalyzing OER is still unclear. Consequently, more studies are essential to figure out what the metal ion actually act in spinel catalyst. In this work, we synthesized a series of spinel materials (AB2O4, A = Co, Zn; B = Co, Cr) via a co-precipitation method in order to find out which part of spinel can electrochemically catalyze OER. X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning electron microscope (SEM), transmission Electron Microscopy (TEM) and Current-Voltage characterization were carried out to realize the mechanism behind the reaction. Finally, we proposed that both sites in spinel can’t catalyze OER directly. However, the Co2+ ion in spinel can transform into Co(O)OH which is a good catalyst for OER. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/49579 |
DOI: | 10.6342/NTU201602765 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學系 |
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