Developing a Gas-Phase Photoelectrocatalytic (Pec) Process and Applying It to Organic Vapor Removal

[[abstract]]本研究規劃連續三年之研究計畫，旨在研發「氣相光電催化分解反應系統(gas-phase photoelectrocatalytic(PEC) reaction process)」，研究中將應用磁控濺鍍技術，製備多種光 觸媒薄膜電極晶片，並於相關間片的製備前，先利用「雷射乾蝕刻技術」在擬作為光觸 媒底材之氧化鋁陶瓷片上，鍍上銀膠梳型電路。其後，再分別濺鍍以單純二氧化鈦 (TiO2)、可見光可作用之摻雜碳 TiO2、或複合氧化亞銅(Cu2O)之 TiO2 等薄膜電極，同時 藉由外加電動勢的協助，希望能增加相關光觸媒晶片的活性與反應的量子效率。本研究 分別選擇甲基第三丁基醚(MtBE)、丙酮(Acetone)、苯(Benzene)等三類典型揮發性有機物 為目標污染物，探討它們在不同實驗條件下的分解速率與反應產物的差異，本研究特別 嘗試探討外加電壓對於揮發性有機物蒸氣分解效能之影響。在擬定的系列實驗中，將藉 由不同反應環境條件的測試實驗(如：改變施加電壓、觸媒配方、水蒸氣含量、污染物 種類與濃度、反應溫度、光源種類與強度等)，探討不同環境操作因子，對光觸媒電子/ 電洞再結合速率與污染物分解速率的影響；另外，在反應機制的探討方面，本研究將分 別經由半導體晶相與結晶表面形貌等物理特性的分析、平帶電位的檢測、半導體氧化/ 還原電位的測定、觸媒表面氫氧自由基的定量分析、以及半導體晶片有機物吸附量及其 導電特性改變行為等資訊，深入探討光電催化分解反應機制，以提供作為未來光觸媒材 質製備或程序改善的參考依據。針對本計畫之執行，各分年的工作重點包括：第一年研 究主要在於光觸媒電極晶片之製備，並進行觸媒物理特性、光電特性、污染物光電催化 分解速率等特性的測定，並希望能初步篩選較佳的觸媒配方；第二年研究重點則在於探 討環境因子和導電電路型式，對於光生電子傳的速率與污染物分解速率之影響，探討兩 者之相關性；第三年研究將根據先前的研究經驗，建置標準化光觸媒活性檢測設施，探 討污染物分解路徑與光電催化反應機制。[[abstract]]A continuous 3-yrs study is proposed here to investigate gas-phase photoelectrocatalytic (PEC) oxidation process to control typical volatile organic pollutants (MtBE, acetone and benzene). Three kinds of thin-film photocatalysts including simple TiO2, carbon-doped TiO2 and Cu2O-composited TiO2 will be prepared with sputtering technologies in the study. They are prepared by depositing thin layer of TiO2 onto porous Al2O3 plates which are pre-assembled with Ag comb-pattern wires. The Ag comb-pattern wires can conduct photo-generated electrons off the photocatalysts, which can retard the recombination rate of electron-hole pairs of photocatalysts. An external bias will be also applied to the proposed PEC reaction system for achieving high oxidation rates of the tested pollutants. Some major tusks will be worked on in this proposed study, which includes to prepare thin-film photocatalyst probes via sputtering processes, to qualify and semi-quantify surface characteristics (i.e., crystalline structure, roughness, energy gap….) of prepared samples, to determine photocatalytic activities and electrochemical properties of photocatalysts, and to establish the relationships among degradation rates of pollutants with process operation parameters such as, bias, humidity, types of photocatalysts, types and concentration of reactants, reaction temperature, light sources. In addition, reaction intermediates and products will be quantified for establishing their degradation pathways. The role of the external bias playing in the PEC reaction for pollutant oxidation will be particularly discussed for investigating reaction mechanisms. Finally, based upon the achieved results in this study, a standard activity testing setup for photocatalysts will be proposed.[[note]]NSC102-2221-E327-002-MY