在不鏽鋼網上製備氧化鋅奈米棒於光催化效率增強之應用

Abstract

近年來，由於一維奈米材料具備有卓越的化性與物性，引領了一個新興的研究領域。在眾多材料之中，又以氧化鋅最受矚目，這是因為他獨特的光學、電性與壓電等特性，都可被廣泛的應用。在本研究中提出了一個製備方法使得一維氧化鋅奈米結構可以被更有效地應用。在不鏽綱網上成長出排列良好的氧化鋅奈米棒陣列，並將其應用於光催化上。此外透過生長於不銹鋼網基材的方式，使氧化鋅奈米棒具有高的面積體積比，可以更有效率的針對非生物不可分解型的染料進行光分解。 在本論文中乃是利用溶液的環境下將氧化鋅奈米棒陣列成長於不銹鋼網上。首先，利用熱分解方式沈積氧化鋅奈米核種於不銹鋼網上，並藉著水溶液法有效將氧化鋅奈米棒陣列成長於不銹鋼網上。最後將已成長好之試片置於不同反應濃度之染料中並照射三小時的紫外光（波長245 奈米）進行光催化反應，透過量測紫外、可見光光譜可以藉此得知溶液中所剩餘染料的濃度與照射紫外光時間之關係。在不銹鋼網上成長氧化鋅奈米棒陣列可以透過照射紫外光方式，針對四種不同類型的染料進行光催化，其中分別為啶染料（甲基藍）、蒽染料（羅丹明6G）、偶氮染料（酸性橙7、甲基橙）與吡啶染料（四硝基苯酚）。在研究中所使用的五種染料分別為具有顏色的甲基藍、羅丹明6G、甲基橙、酸性橙7與透明的四硝基苯酚，可以用於評估在不銹鋼網上成長氧化鋅奈米棒陣列具備有全波段的光催化效果。透過結果分析可以發現在不銹鋼網上所成長之氧化鋅奈米棒陣列可以完全將五種染料進行光分解。此外藉著不同的參數測試，如多次成長、不同孔洞的尺寸、不同大小的不鏽鋼網與不同長度的奈米棒，都可以有效增強光催化效果。除此之外，此氧化鋅奈米棒陣列的光催化能力是具備有可重複使用及良好再現性，即使經過十次實驗後，對於甲基藍與羅丹明6G的光催化分解能力也能分別維持在91% 與86%。在不鏽鋼網上成長之氧化鋅奈米棒陣列，具備有大面積成長、簡易、低成本、高表面積與高光催化效能，此一方法在汙染物的分解或是廢水處理再利用上具有極大應用的潛力。

Recently, one-dimensional nanostructures are a new class of advanced materials that have been receiving a lot of research interest due to their superior physical and chemical properties. In many different kinds of materials, zinc oxide is one of the most important materials and has attracted much attention because of its unique optical, electrical, and piezoelectric properties for versatile applications. The present study proposes a fabrication method to improve the applications of 1D ZnO nanostructures. The well-aligned ZnO nanorods array on the stainless steel mesh can be used in photocatalystic applications. The stainless steel mesh provided an extensive surface area and facilitated efficient mass transfer. The nanorods array exhibited excellent photocatalytic activity and extensive enhanced properties due to high surface to volume ratio for the photodecomposition of a non-biodegradable azo dye. In this thesis, well-aligned ZnO nanorods array were grown on the stainless steel mesh substrate using a solution-based process. First, a ZnO seeds layer was prepared on the stainless steel mesh substrate by thermal decomposition. ZnO nanorods array were grown on the substrate using an aqueous solution method. Finally, the ZnO nanorod-coated substrate was immersed in the different concentration of dye solution and irradiated the UV light (245 nm) for 3 h. The remaining dye in the solution as a function of UV irradiation time was performed by an UV-visible spectrum. The ZnO nanorods array on the stainless steel mesh substrate can be used to irradiate UV light for the photocatalytic degradation of four different models acridine-dye (methylene blue), anthracene-dye (rhodamine 6G), azo-dye (acid Orange 7, methyl orange) and pyridine-dye (4-nitrophenol). Herein, five kinds of dyes used in photocatalysis including colored methylene blue, rhodamine 6G, methyl orange, acid orange 7, and transparent 4-nitrophenol to prove that it can be photocatalyzed in all-band absorbable wavelength. The result exhibits that complete decolorization of the five kinds of dye solution may be achieved. Further tests by different parameters, such as growth times, different size of holes, different size of stainless steel mesh, and different length of nanorods can effectively enhance the photocatalytic efficiency. In addition, the repeatability of ZnO nanorods photocatalysis in dye photodecomposition has been proved. After ten cycles of photodecomposition, the photocatalytic efficiency reduced to about 91% and 86% for methylene blue and rodamine 6G, respectively. The ZnO nanorod arrays on the stainless steel mesh provides a large-scale, facile, low-cost, high surface area, and high photocatalytic efficiency, which shall be of significant value for practical applications of the decomposition of environment pollutants and reusing of wastewater treatment.