化學浴沉積法衍生複合型和固溶體型ZnO光觸媒膜的製備與特性分析

Preparations and characterizations of coupling type and solid-solution type of ZnO photocatalytic films via chemical bath deposition method

張庭瑀(Ting-Yu Chang)

指導教授 ： 余宣賦

淡江大學/工學院/化學工程與材料工程學系碩士班/碩士(2021年)

https://doi.org/10.6846/TKU.2021.00260

摘要

本研究利用化學浴沉積技術(chemical bath deposition；CBD)將具有優異光催化能力之氧化鋅膜均勻且連續地被覆在經過KMnO4(aq)活化處理的玻璃管表面，並結合光化學還原法(photochemical reduction)將銀離子還原至氧化鋅表面上，再經過適當地熱處理，製備出複合型Ag/ZnO光觸媒膜和固溶體型Ag-ZnO光觸媒膜。製得之ZnO膜、複合型Ag/ZnO膜與固溶體Ag-ZnO膜藉由X光繞射儀、掃描式電子顯微鏡、能量色散X-射線譜、漫反射光譜圖和紫外光-可見光光譜儀等進行分析以瞭解其特性。研究中探討基材活化步驟、CBD溶液中氨水及乙醇胺體積比、熱處理程序對ZnO光觸媒膜特性及光催化能力的影響；複合型Ag/ZnO膜和固溶體型Ag-ZnO膜則探討AgNO3(aq)濃度與光照還原時間和熱處理程序對其光催化活性的影響。
使用適當的氨水和乙醇胺比例下，可在經KMnO4(aq)活化處理的玻璃管表面均勻生成CBD衍生之ZnO膜。CBD溶液中氨水及乙醇胺之配比及熱處理程序會影響其衍生之ZnO膜的結晶度、膜厚及光催化能力。CBD衍生ZnO膜光催化降解水中亞甲基藍的視反應級數為一階。光催化測試中，以氨水及乙醇胺體積比為4：10且經500℃煆燒1小時所製得之ZnO膜光催化效能最佳，其k值為37.033 L/(m^2∙h)。利用光化學還原法成功在CBD衍生的ZnO表面上附著金屬銀顆粒，製備過程中AgNO3(aq)濃度與光照還原時間會影響表面銀顆粒的尺寸和其光催化效能。光催化降解測試中，不同參數條件下所製備的複合型Ag/ZnO膜之光催化能力皆比純ZnO膜高（提升13%~25.5%），以硝酸銀水溶液濃度為0.2mM光照還原時間1小時之複合型Ag/ZnO光觸媒膜表現出最佳的光催化效能（k值為50.092 L/(m^2∙h)）；金屬材料與半導體光觸媒的異質接合結構對於提升光催化效能具有正向的結果。另外，以光化學還原法將Ag+還原至未經熱處理之ZnO膜表面後，藉由高溫煆燒的方式，給予能量使Ag進入到ZnO的結構中，可製備出固溶體型Ag-ZnO光觸媒膜，並且改變ZnO之能隙。由於Ag摻入ZnO晶體結構中，造成固溶體型Ag-ZnO光觸媒之能隙變大，且導致對Ag-ZnO膜的光催化效能有負面的影響。

關鍵字

氧化鋅 ； 複合型 ； 固溶體型 ； 光觸媒膜 ； 化學浴沉積技術

並列摘要

In this study, zinc oxide films were uniformly deposited on the KMnO4-activated surface of glass tubes by chemical bath deposition method (CBD). A photochemical reduction method was used to reduce the Ag+ in water to form metallic Ag nanoparticles on the ZnO surface. The ZnO films so obtain were then thermally treated to produce the coupling type (Ag/ZnO) and the solid-solution type (Ag-ZnO) photocatalyst films. The obtained ZnO films, composite Ag/ZnO films and solid-solution Ag-ZnO films were characterized using X-ray diffractometer, scanning electron microscope, energy dispersive spectroscopy, diffuse reflectance spectrum and ultraviolet-visible spectrophotometer. Effects of the substrate activation step, the volume ratio of ammonia to ethanolamine in the CBD solution, and the heat treatment process on characteristics and photocatalytic abilities of the prepare ZnO photocatalytic films were investigated and discussed. Then, effects of AgNO3(aq) concentration, reduction time and heat treatment process on photocatalytic activities of the Ag/ZnO films and the Ag-ZnO films were investigated.
The CBD-derived ZnO films were uniformly coated on the KMnO4(aq)-activated surfaces of glass tubes with appropriate ratios of ammonia to ethanolamine. The crystallinity, film thickness and photocatalytic ability of the CBD-derived ZnO films were affected by the ratio of ammonia and ethanolamine in the CBD solution and the heat treatment process. The apparent reaction order of photocatalytic degradation of methylene blue in water by the CBD-derived ZnO films was first order. The CBD-derived ZnO film prepared using a volume ratio of ammonia to ethanolamine of 4:10 and calcined at 500 ℃ for 1 hour possessed high photocatalytic activity with its k = 37.033 L/(m2‧h).
Silver nanoparticles were attached to the surface of ZnO columns by photochemical reduction method. The sizes of silver nanoparticles attached to ZnO columns and photocatalytic abilities of the produced Ag/ZnO films were affected by the concentration of AgNO3(aq) and reduction time used during preparation. The photocatalytic abilities of Ag/ZnO films prepared under different condition ave 1~1.5 times of that of the pure ZnO films. The Ag/ZnO photocatalyst film with 0.2mM AgNO3(aq) and light reduction time of 1 hour gave the best photocatalytic ability (k=50.092 L/(m^2‧h)), indicating that the heterojunction structure of metal materials and semiconductor photocatalyst had positive results for improving photocatalytic ability. In addition, after Ag+ was reduced to Ag on the surface of uncalained ZnO films, the attached Ag nanoparticles diffused into the crystallites of ZnO, by high temperature calaination (300 or 400), to form Ag-ZnO photocatalytic films. The energy gap of the Ag-ZnO photocatalyst was increased. The incoporation of Ag elements into ZnO crystals to form solid-solution type of ZnO photocatalytic films did not, in general, have a positive effect on photocatalytic ability of the films.

並列關鍵字

ZnO ； coupling ； solid-solution ； photocatalytic films ； chemical bath method

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