表面電漿子增益光碟片污水處理系統

對於生活在21世紀的人類而言，環境保護是文明發展所必須面對的一大課題；而在水資源有限的台灣，水資源的維護與污水處理更是環保議題中不可忽視的部份。本研究中所探討的是以電漿子增益之半導體光觸媒分解水中有機污染物。近代半導體光觸媒之研究約始於1969年，由日本的K. Honda和A. Fujishima兩位教授首先以實驗證明二氧化鈦光觸媒可應用在氫燃料生成的技術。自此之後，許多研究人力與資源投入了光觸媒的研究，也包含了利用光觸媒進行污水處理；其中，氧化鋅光觸媒以高光敏感度、高物理穩定性、低成本與大能隙等優勢，成為最受歡迎的光觸媒材料之一。　　光觸媒以光作為啟動化學反應的能量源，而研究人員的終極目標為研發出可直接在地表以太陽光驅動之架構。然而，具應用價值之半導體光觸媒通常擁有高能隙，使之只能吸收紫外光的光子；對於太陽光譜佔了90%以上能量的可見光與進紅外光而言，半導體光觸媒是無法直接運用的。研究人員提出了許多方法，嘗試去改變光觸媒的光學性質，主要分成添加其他物質和在半導體中製作缺陷等兩種方法。本研究主要探討的方法就是添加具侷域表面電漿共振特性之奈米金屬粒子至光觸媒中，以其熱電子效應使整個光觸媒系統可利用可見光進行化學反應，並提升整體反應效率。　　本研究開發了一個大面積製作含有奈米金屬粒子之氧化鋅奈米柱，此結構是生長於光碟片基板上，並可結合特殊設計之旋轉反應器進行高效率的污水分解程序。樣品成長過程中，氧化鋅奈米柱的生長是以水熱法達成，水熱法可以相對低的成本與溫度成長徑直的奈米柱，使奈米柱合成過程保持光碟片基板的完整性。光碟片基板雖然不耐熱，但是擁有可高速旋轉的物理結構以及耐衝擊等優勢，非常適合應用於本研究。本研究中使用的奈米金屬粒子為銀粒子，擁有非常強的侷域表面電漿共振。本研究中使用濺鍍法在氧化鋅奈米柱表層形成銀奈米顆粒。氧化鋅奈米柱以及銀奈米粒子的表面形貌由掃描式電子顯微鏡進行觀測。本研究中以甲基橙水溶液模擬污水，而其濃度可由穿透光譜系統進行監控。在樣本參數最佳化的情況下，本系統可在20分鐘內分解溶液中90%以上之甲基橙分子。

關鍵字

光催化；氧化鋅；表面電漿子學；旋轉反應器；廢水處理

並列摘要

Environmental protection is one of the most crucial issues of the human civilization in the 21st century. Researchers have been working on using semiconductor photocatalyst for organic chemical decomposition since 1969, the year when Honda-Fujishima effect was experimentally demonstrated. Among the photocatalytic materials, zinc oxide (ZnO) has attracted much attention due to its high photosensitivity, stability, low cost, and wide band gap. However, the wide band gap of semiconductor photocatalysts results in low absorption in the visible and infrared region. This property limits the possibility of the ultimate goal of photocatalysts: using solar energy for direct chemical reaction, since the over 90% of solar power is carried by photons in visible or infrared region. Researchers have been working on artificial defects and additives to modify optical properties of photocatalyst. The localized surface plasmon resonance, together with its induced hot electron effect, is one of the most promising strategies to solve the enigma. In this work, a process of growing large-area plasmonic-nano-particles-decorated ZnO nanorods on the polycarbonate optical disk substrate was developed, while a corresponding photocatalytic rotational reactor was fabricated. Hydrothermal process was adapted to grow ZnO nanorods perpendicular to the optical disk substrate at relatively lower temperature. The optical disk substrate has advantages of durable property in fast rotation and high impact-resistance. The plasmonic nano-particles, in this case, silver nano-particles, were deposed on the ZnO nanorods by direct sputtering. The morphology of ZnO nanorods and plasmonic nano-particles was investigated by Scanning Electron Microscope (SEM). The photocatalytic activity of the sample was evaluated by the degradation of methyl orange (MO) as a model compound in aqueous solution, and the decomposition rate of MO molecules is monitored by the optical spectroscopy measurements. In the optimized condition, less than 10% of the MO remained in the aqueous solution after a 20-minute treatment in the rotational reactor with our sample.

並列關鍵字

Photocatalysis ； Zinc Oxide ； Plasmonics ； Hot Electrons ； Rotational Reactor ； Wastewater Treatment

參考文獻

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[2] S. Al-Qaradawi and S. R. Salman, "Photocatalytic degradation of methyl orange as a model compound," J Photochem Photobiol A 148, 161 (2002).

[3] C. A. Gueymard, D. Myers, and K. Emery, "Proposed reference irradiance spectra for solar energy systems testing," Sol Energy 73, 443 (2002).

[4] H. A. Atwater and A. Polman, "Plasmonics for improved photovoltaic devices," Nat Mater 9, 205 (2010).

[5] Y. L. Chen, L. C. Kuo, M. L. Tseng, H. M. Chen, C. K. Chen, H. J. Huang, R. S. Liu, and D. P. Tsai, "ZnO nanorod optical disk photocatalytic reactor for photodegradation of methyl orange," Optics express 21, 7240 (2013).

國際替代計量

表面電漿子增益光碟片污水處理系統

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