臺灣博碩士論文加值系統

利用溶膠凝膠法製備TiO2和NiO/TiO2之p-n接面光觸媒，分別探討溶劑和摻雜氧化鎳對製備出的觸媒之顆粒結構、特性及光催化活性的影響。當使用不同醇類當溶劑所製備出的二氧化鈦光觸媒，發現銳鈦礦結晶量隨著所使用醇類的碳鏈越長而減少。這是因為使用長碳鏈的醇類當溶劑在溶膠凝膠的過程中其水解和縮合的速度較慢而所導致。而且使用長碳鏈的醇類當溶劑所製備出的二氧化鈦顆粒凝聚較為嚴重，導致比表面積相對較小。因此實驗結果證明用短碳鏈的醇類當溶劑所製備出的二氧化鈦光觸媒有較佳的光催化活性。
然而在NiO/TiO2之p-n接面光觸媒，可得知當摻雜氧化鎳後，其二氧化鈦銳鈦礦晶相轉變成金紅石晶相的轉換溫度提高。NiO/TiO2光觸媒顆粒也隨著煅燒溫度的提高而增加。由實驗結果證明當摻雜0.1%和0.5%之氧化鎳所形成的NiO/TiO2之p-n接面光觸媒比純TiO2光觸媒有較佳的光還原活性。將此結果歸因於三個原因。第一，摻雜氧化鎳會抑制了二氧化鈦之銳鈦礦晶相轉變成金紅石晶相。第二，摻雜氧化鎳會抑制二氧化鈦顆粒的成長，使得觸媒有較大的比表面積。第三，氧化鎳扮演電洞捕捉的角色，抑制了光產生電子-電洞對的再結合。

The effects of solvent used in sol-gel process for TiO2 synthesis and doping of NiO formed p-n junction photocatalyst on the particle structure, characteristics and photocatalytic activity were studied. The anatase phases of TiO2 prepared with different alcohols as solvent by sol-gel method and calcined at 500 oC for 2 hours were decreased with alcohols of more carbons because addition of alcohols of more carbons might reduce the rates of hydrolysis and condensation. The aggregation of prepared TiO2 was more serious for using alcohols of more carbons as solvent; therefore, specific surface area was decreased. The photoreduction activity of TiO2 prepared with alcohols of fewer carbons was higher than more carbons.
On the p-n junction NiO/TiO2 photocatalyst, the transformation temperature from anatase to rutile crystal phase was enhanced greatly for NiO-doped TiO2. The particle size of NiO/TiO2 photocatalyst increased with the increasing of calcining temperature. The photoreduction activity of NiO/TiO2 photocatalysts doped with 0.1 % and 0.5 % NiO were higher than pure TiO2. The results can be ascribed to three possible reasons. First, the crystal phase transformation of TiO2 from anatase to rutile was prevented with doped NiO. Second, NiO doped could inhibit the growth of the TiO2 grains to increase the specific surface area of the catalysts. Third, NiO doped act as trap for holes to inhibit the recombination of photogenerated electron-hole pairs.

Chapter 1 Introduction
1.1 Background
1.2 Objectives and Scope

Chapter 2 Literature Review
2.1 Introduction of Photocatalyst
2.2 Modification of Photocatalyst
2.2.1 Metal-Doped Photocatalyst
2.2.2 Non-Metal-Doped Photocatalyst
2.2.3 Metal Oxide-Doped Photocatalyst
2.3 Introduction of p-n Junction Photocatalyst
2.3.1 p-n Junction Theory
2.3.2 Design of p-n Junction Photocatalysts
2.3.3 NiO and p-n Junction Photocatalyst
2.4 Preparation of p-n Junction Photocatalyst
2.4.1 Solid-State Reaction
2.4.2 Incipient Wetness Impregnation
2.4.3 Photodeposition
2.4.4 Sol-gel Method
2.5 Operation Factors on Photocatalyst Preparation by Sol-gel Method
2.5.1 Metal Alkoxides
2.5.2 pH Value
2.5.3 Hydrolysis Temperature
2.5.4 Calcined Temperature
2.5.5 Type of Solvent

Chapter 3 Experimental Procedures and Equipments
3.1 Instruments
3.2 Materials
3.3 Apparatus
3.4 Experimental Procedures
3.4.1 Experimental Framework
3.4.2 Catalyst Preparation
3.4.3 Characterization Analysis of Photocatalysts
3.4.4 Decomposition of Cr(Ⅵ) in photocatalytic process
3.4.5 Background Experiments

Chaper 4 Results and Discussion
4.1 Characterizations of TiO2 Catalysts Prepared with Different Solvents
4.1.1 Thermal Analysis
4.1.2 X-ray Diffraction (XRD) Analysis
4.1.3 UV-vis Diffuse Reflectance Spectra (DRS) Analysis
4.1.4 Scanning Electron Microscopy (SEM) Analysis
4.1.5 Specific Surface Area Measurement
4.1.6 Zeta Potential Analysis
4.2 Characterizations of NiO/TiO2 Catalysts Calcined at Various Temperatures
4.2.1 X-ray Diffraction (XRD) Analysis
4.2.2 Scanning Electron Microscopy (SEM) Analysis
4.2.3 Specific Surface Area Measurement
4.3 Characterizations of TiO2 Catalysts Doped Various NiO Dosages
4.3.1 Thermal Analysis
4.3.2 X-ray Diffraction (XRD) Analysis
4.3.3 UV-vis Diffuse Reflectance Spectra (DRS) Analysis
4.3.4 X-ray Photoelectron Spectroscope (XPS) Analysis
4.3.5 Surface Photovoltage Spectroscopy (SPS) Analysis
4.3.6 Specific Surface Area Measurement
4.3.7 Zeta Potential Analysis
4.4 Photocatalytic Reduction of Cr(VI) in Aqueous Solutions using TiO2 and NiO/TiO2 Photocatalysts
4.4.1 Background Experiments of Photocatalysis
4.4.2 Effect of TiO2 Catalysts Prepared with Different Solvents
4.4.3 Effect of TiO2 Catalysts Doped Various NiO Dosages
4.4.4 Effect of NiO/TiO2 Catalysts Calcined at Various Temperatures
4.4.5 Addition of Hole Scavenger

Chaper 5 Conclusions and Recommendations
5.1 Conclusions
5.2 Recommendations

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