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標題: | 鈦亞磷酸鹽應用於光催化海水生產氫氣 Titanium Phosphite for photocatalytic hydrogen evolution from sea water |
作者: | Cheng-Ting Lee 李承庭 |
指導教授: | 吳紀聖 |
關鍵字: | 光催化,鈦亞磷酸鹽,海水產氫,太陽能, photocatalysis,titanium phosphite,hydrogen evolution from seawater,solar energy, |
出版年 : | 2018 |
學位: | 碩士 |
摘要: | 本研究旨在探討鈦亞磷酸鹽材料(以M1代稱之)應用於光催化海水生產氫氣的能力。M1為一種從水熱法製得之新穎材料,由單晶X射線繞射 (SXRD)及X射線光電子能譜 (XPS)等分析方法定義出M1之化學式為Mg0.5(H2O)3[TiIIITi2IV(HPO3)6]‧x(H2O) (x ≅ 0.4)。此材料的特點為結構中的鈦是Ti3+/Ti4+的混價,具有優越的可見光吸收能力,且在三極式電化學系統中證實M1材料對太陽光會產生光電流之響應,因此可以做為吸收太陽光行光催化反應的光觸媒材料。本研究將M1材料應用於光催化產氫,發現在純水環境及2 mM FeCl2 (pH 2.4, adjusted by H2SO4) 犧牲試劑環境皆具有產氫能力,且犧牲試劑的存在可以有效地提升M1產氫速率為純水環境的1.27倍。為了進一步提升M1之產氫速率,本研究亦嘗試以光沉積法負載不同數量的奈米Pt顆粒於M1材料表面,經測試發現,M1_1.0Pt材料具有最佳光催化產氫活性,其產氫速率約為原本M1材料的三倍。
收集反應後的M1材料,以XPS分析之後發現M1材料若於純水環境進行光催化產氫反應,M1材料會被光激發之電洞光腐蝕,即材料結構中的Ti3+會被氧化成Ti4+。在光催化系統中加入2 mM FeCl2犧牲試劑則可吸收電洞,避免光腐蝕現象發生,因此,FeCl2犧牲試劑同時具有提升氫氣產量及避免光腐蝕現象發生的功能。然而,消耗犧牲試劑來進行光催化產氫會使此反應之經濟效益降低,因此本研究嘗試以天然海水(取自淡水河出海口與三仙台海濱)及人工調配海水(溶解鹽類於純水)進行光催化產氫反應,使用海水中豐富的氯離子作為犧牲試劑。研究發現在純水中添加海水內含的離子,可以提升光催化氫氣產量及避免觸媒受到電洞光腐蝕。與純水相比,使用天然的淡水河出海口海水進行長時間光催化產氫反應,M1了展現更佳的穩定性。 This research was dedicated to investigating the potential application of titanium phosphite, denoted as M1, in the photocatalytic hydrogen evolution from sea water. The M1 was a novel material synthesized by the hydrothermal method. By means of single-crystal X-ray diffraction (SXRD) and X-ray photoelectron spectroscopy (XPS), the chemical formula of M1 was found to be Mg0.5(H2O)3[TiIIITi2IV(HPO3)6]‧x(H2O) (x ≅ 0.4), which featured composed-valence Ti3+/Ti4+. The M1 could absorb visible light mostly, which might result from Ti3+ atoms in M1’s structure, and showed photocurrent response in a 3-electrode system under simulated sunlight irradiation. Therefore, M1 was applied in sunlight-driven photocatalytic hydrogen evolution reaction. M1 showed the activity of photocatalytic hydrogen evolution in both pure water and solution of 2 mM FeCl2 (pH 2.4, adjusted by H2SO4). In addition, with the presence of 2 mM FeCl2, which was a sacrificial agent, the hydrogen evolution rate could be enhanced to 1.27 times compared with the pure water. In order to further improve the photocatalytic activity of M1, photo-deposition method was used to load different numbers of Pt nanoparticles onto M1 surface. The M1_1.0Pt gave the highest photocatalytic activity for hydrogen evolution, and its hydrogen evolution rate tripled after loaded with Pt. The M1 was collected after photocatalytic hydrogen evolution, then was analyzed by XPS. The results showed that Ti3+ in M1 structure was oxidized to Ti4+ by photo-induced holes in pure water environment. This phenomenon was called hole-induced photocorrosion. If the sacrificial agent, 2mM FeCl2, was present in photocatalytic system, holes could be neutralized by FeCl2. Thus photocorrosion could be avoided. Therefore, the sacrificial agent FeCl2, could both enhance hydrogen evolution and prevent photocorrosion of M1. However, the consumption of sacrificial agent to conduct hydrogen evolution reaction would decrease economic profit. To solve this problem, this research tried to conduct the reaction of photocatalytic hydrogen evolution using seawater, which is an unlimited and free resource. Two sources of seawater were taken from the estuary of Tamsui River, and east coast of Taiwan. The ions in seawater could act as sacrificial agent. The experimental result showed that adding the ions of seawater into pure water could enhance photocatalytic hydrogen evolution of M1 as well as prevent M1 from photocorrosion. Furthermore, photocatalytic hydrogen evolution from natural seawater (estuary of Tamsui river, Taiwan) showed better stability than that of pure water in a long-term test. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/69118 |
DOI: | 10.6342/NTU201801781 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學工程學系 |
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