氧化亞銅及銀奈米粒子共修飾氧化鋅奈米線於光觸媒應用

Application of ZnO Nanowires Co-modified with Cuprous Oxide and Silver Nanoparticles in Photocatalysis

江茂源(Chiang, Mao Yuan)

指導教授 ： 林鶴南

國立清華大學/工學院/材料科學工程學系/碩士(2015年)

摘要

本實驗將氧化亞銅及銀奈米粒子修飾於氧化鋅奈米線，氧化鋅奈米線先經由熱蒸鍍法長在摻雜氟的氧化錫基板上，再經由光還原法將氧化亞銅及銀奈米粒子分別或者是同時修飾於氧化鋅奈米線上。相較於未經修飾氧化鋅奈米線，經過修飾的氧化鋅奈米線展現較佳的光觸媒表現，其中又以兩種奈米粒子共修飾的氧化鋅奈米線有最佳的光觸媒表現。
藉由掃描式電子顯微鏡與穿透式電子顯微鏡觀察到奈米粒子的表面形貌並確認結構；螢光光譜圖的分析看出修飾過後奈米線在紫外放光波段強度下降，推斷為電子電洞對的再結合率降低。吸收光譜圖顯示出修飾過後奈米線光吸收率會提升，其成因為小能隙的氧化亞銅與會產生表面電漿的銀可幫助吸收光。
在功率100W的鹵素燈下藉由分解濃度為50 µM的羅丹明B (rhodamine B)水溶液，並經由最小平方法計算其一階反應速率，共修飾的氧化鋅奈米線的反應速率最高，為0.32 µM/min，是未修飾氧化鋅奈米線的3.2倍。另外有在實際太陽光底下進行共修飾氧化鋅奈米線的光觸媒實驗，在80分鐘觀察到95%的分解效率，一階反應速率為0.73 µM/min。顯示出共修飾氧化鋅奈米線有做為光觸媒材料的實用價值與潛力。

關鍵字

氧化鋅奈米線 ； 氧化亞銅奈米粒子 ； 銀奈米粒子 ； 光觸媒

並列摘要

In this work, we report on the enhanced photocatalytic activity of ZnO nanowires (NWs) modified with cuprous oxide and silver nanoparticles (NPs). ZnO NWs were first grown on fluorine-doped tin oxide substrates by thermal evaporation without catalysts. They were then modified with cuprous oxide or silver NPs, or both, by photoreduction. The NP modified NWs show better photocatalytic performance than as-grown NWs. Furthermore, ZnO NWs co-modified with cuprous oxide and silver NPs have the best photocatalytic efficiency.
From the scanning electron microscopy and transmission electron microscopy images, the morphologies and the structures of the NPs are confirmed. The ultraviolet emissions of modified ZnO NWs decrease in the photoluminescence spectra, revealing that the recombination of electron-hole pairs is reduced. The absorption spectra show that modified ZnO NWs have higher absorption in both visible and ultraviolet regions, which is due to the narrow band gap of cuprous oxide NPs and the plasmonic effect of silver NPs.
The photocatalytic activities of the NWs were evaluated by degrading a 50 µM rhodamine B solution under the illumination of a 100 W halogen lamp. The zeroth-order kinetic constant of the co-modified ZnO NWs is 0.32 µM/min, which is 3.2 times as high as that of as-grown ZnO NWs. The co-modified NW sample has also been tested under direct sunlight illumination. A kinetic constant of 0.73 µM/min and a degradation efficiency of 95% in 80 min have been obtained.

並列關鍵字

zinc oxide nanowire ； cuprous oxide nanoparticle ； silver nanoparticle ； photocatalysis

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