本研究之主要目的將藉燃料電池習用之由電極與固態電解質形成電化學迴路之概念，應用固態電解質於外加電位施加之氣相光觸媒催化反應系統形成電場，將外加電位施加於氣相光觸媒催化反應程序中，以減少光觸媒電極表面之電子–電洞再結合，更有效率的將揮發性有機物加以分解。本研究首先於基板上披覆TiO2形成光陽極，將光陽極與固態電解質緊密結合。針對光陽極之光電特性進行分析，包括光觸媒披覆厚度以及不同光陽極基板等，以作為後續反應器設計之依據。研究結果指出，光陽極在TiO2披覆厚度為6.28μm以及不鏽鋼基板條件下，實際光催化及光電催化分解氣相異丙醇時皆展現最好的分解效率，因此後續實驗將選用此光陽極。
將製備所得之光陽極應用於氣相光電催化分解異丙醇，並探討各項實驗操作變因(如：異丙醇初始濃度、外加電位強度、相對濕度、初始氧濃度以及外加電位形式)對異丙醇的轉化率之影響及反應動力行為。實驗結果顯示，將外加電位導入光催化反應中有效提升異丙醇分解效率，由於外加電位強制將電子導走，減少電子電洞對再結合機率；發現溼度對於光電催化程序比光催化程序來的不敏感，由於光電催化程序反應中進行電解水作用使環境中溼度減少，因而減少水分子與異丙醇競爭吸附於光觸媒活性位置；光電催化程序引入半方波外加電位形式與直流電相比，提升光電催化分解異丙醇性能。此外應用Langmuir–Hinshelwood動力學模式，建立異丙醇之反應動力模式，模擬在不同異丙醇初始濃度、外加電位強度以及氧濃度下，光催化及光電催化分解異丙醇之效率，模擬結果顯示，可有效的描述異丙醇分解效率。另外研究甲苯對於光催化及光電催化反應的濕度影響。光電催化分解氣相甲苯過程發現光觸媒失活，此外提高溼度可延緩光觸媒失活。

In this study, the photoelectrochemical reactor constructed by the structure design of PEM fuel cell was used for the photoelectrocatalytic decomposition of organics in gas phase. The photoelectrocatalytic properties of photoanodes with different TiO2 thickness are examined. The experimental results indicated that the 6.28 μm thickness of TiO2 film shows the highest photocatalytic activity among all the thickness investigated.
The effects of initial isopropanol concentration, bias potential, relatively humidity, initial oxygen concentration and driving modes of bias potential were investigated on the photocatalytic and photoelectrocatalytic processes in anode chamber of the photoelectrochemical reactor. Decomposition of gaseous isopropanol was efficiently enhanced by photoelectrocatalytic process because the photogenerated electrons were efficiently driven from TiO2-coated photoanode into external circuit be the application of bias potential, further inhibiting electron-hole recombination. Removal of isopropanol was decreased drastically with relative humidity for experiments conducted with relative humidity greater than 10%. In addition, photoelectrocatalytic decomposition of gaseous isopropanol was observed to be less sensitive to humidity for experiments applied with bias potential higher than 2.5V. The photoelectrocatalytic decomposition of isopropanol was greatly enhanced under the half-rectified square wave mode, compared to under the constant direct current mode widely used in the photoelectrochemical cells. Experimental results for the decomposition of gaseous isopropanol by photoelectrocatalytic process can be adequately described by the developed Langmuir–Hinshelwood kinetic model. Furthermore, study the effects of relative humidity on the photoelectrocatalytic decomposition of toluene in gas phase. The experimental results show that under low relative humidity conditions, the photocatalytic activity of TiO2 was steeply decreased with reaction time due to the accumulation of the partially oxidized reaction intermediates under these conditions.

Alberici, R.M. and Jardim, W.F., “Photocatalytic Destruction of VOCs in the Gas-Phase Using Titanium Dioxide,” Environ. Sci. Technol., Vol. 14, pp. 55–68 (1997).
Ampelli, C., Centi, G., Passalacqua, R. and Perathoner, S., “Synthesis of Solar Fuels by a Novel Photoelectrocatalytic Approach,” Energy Environ. Sci., Vol. 3, pp. 292–301 (2010).
Ao, C.H., Lee, S.C., Yu, J.Z., Xu, J.H., “Photodegradation of Formaldehyde by Photocatalyst TiO2: Effects on the Presences of NO, SO2 and VOCs,” Appl. Catal, B., Vol. 54, pp. 41–50 (2004).
Assadi, A.A., Bouzaza, A. and Wolbert, D., “Photocatalytic Oxidation of Trimethylamine and Isovaleraldehyde in an Annular Reactor: Influence of the Mass Transfer and the Relative Humidity,” J. Photochem. Photobiol. A-Chem., Vol. 236, pp. 61–69 (2012).
Blount, M.C. and Falconer, J.L., “Steady-State Surface Species During Toluene Photocatalysis,” Appl. Catal. B., Vol. 39, pp. 39–50 (2002).
Bouzaza, A., Vallet, C. and Laplanche, A., “Photocatalytic Degradation of Some VOCs in the Gas Phase Using an Annular Flow Reactor: Determination of the Contribution of Mass Transfer and Chemical Reaction Steps in the Photodegradation Process,” J. Photochem. Photobiol. A-Chem., Vol. 25, pp. 212–217 (2006).
Cao, L., Gao, Z., Suib, S.L., Obee, T.N., Hay, A.O. and Freihaut, J.D., “Photocatalytic Oxidation of Toluene on Nanoscale TiO2 Catalysts: Studies of Deactivation and Regeneration,” J. Catal., Vol. 196, pp. 253–261 (2000).
Chang, C.P., Chen, J.N. and Lu, M.C., “Characteristics of Photocatalytic Oxidation of Gaseous 2-Propanol Using Thin-Film TiO2 Photocatalyst,” J. Chem. Technol. Biotechnol., Vol. 79, pp. 1293–1300 (2004).
Chang, C.P., Chen, J.N., Lu, M.C. and Yang, H.Y., “Photocatalytic Oxidation of Gaseous DMF Using Thin Film TiO2 Photocatalyst,” Chemosphere, Vol. 58, pp. 1071–1078 (2005).
Chang, C.P., Chen, J.N., Lu, M.C., “Heterogeneous Photocatalytic Oxidation of Acetone for Air Purification by Near UV-Irradiated Titanium Dioxide,” J. Environ. Sci. Health Part A-Toxic/Hazard. Subst. Environ. Eng., Vol. 38, pp. 1131–1143 (2003).
Daghrir, R., Drogui, P. and Robert, D., “Photoelectrocatalytic Technologies for Environmental Applications,” J. Photochem. Photobiol. A-Chem., Vol. 238, pp. 41–59 (2012).
Diebold, U., “The Surface Science of Titanium Dioxide,” Surf. Sci. Rep., Vol. 48, pp. 53-229 (2003)
Einaga, H., Futamura, S. and Ibusuki, T., “Heterogeneous Photocatalytic Oxidation of Benzene, Toluene, Cyclohexene and Cyclohexane in Humidified Air: Comparison of Decomposition Behavior on Photoirradiated TiO2 Catalyst,” Appl. Catal, B., Vol. 38, pp. 215–225 (2002).
Friedmann, D., Mendive, C. and Bahnemann, D., “TiO2 for Water Treatment: Parameters Affecting the Kinetics and Mechanisms of Photocatalysis,”Appl. Catal. B., Vol. 99, pp. 398–406 (2010).
Gaya, U.I. and Abdullah, A.H., “Heterogeneous Photocatalytic Degradation of Organic Contaminants Over Titanium Dioxide: A Review of Fundamentals, Progress and Problems,” J. Photochem. Photobiol. C-Photochem. Rev., Vol. 9, pp. 1-12 (2008).
Georgieva, J., Armyanov, S., Poulios, I. and Sotiropoulos, S., “An All-Solid Photoelectrochemical Cell for the Photooxidation of Organic Vapours Under Ultraviolet and Visible Light Illumination,” Electrochem. Commun., Vol. 11, pp. 1643–1646 (2009).
Georgieva, J., Valova, E., Armyanov, S., Philippidisa, N., Pouliosa, I. and Sotiropoulos, S., “Bi-Component Semiconductor Oxide Photoanodes for the Photoelectrocatalytic Oxidation of Organic Solutes and Vapours: A Short Review with Emphasis to TiO2–WO3 Photoanodes,” J. Hazard. Mater., Vol. 211-212, pp. 30–40 (2012).
Hiroyuki, M., Katsuyoshi, I., Kazuhito, H., Katsuhiro, A., Masao, M. and Akira, F., “Microscopic Observation of TiO2 Photocatalysis Using Scanning Electrochemical Microscopy,” J. Phys. Chem. B., Vol. 103, pp. 3213–3217 (1999).
Hou, W.M. and Ku, Y., “Photoelectrocatalytic Decomposition of Gaseous Isopropanol in a Polymer Electrolyte Photoreactor,” J. Solid State Electrochem., Vol. 17, pp. 737-741 (2012).
Ichikawa, S., “Chemical Conversion of Carbon Dioxide by Catalytic Hydrogenation and Room Temperature Photoelectrocatalysis,” Energy Convers. Manage., Vol. 36, pp. 613–616 (1995).
Itoh, N., Xu, W.C., Hara, s. and Sakaki, K., “Electrochemical Coupling of Benzene Hydrogenation and Water Electrolysis,” Catal. Today, Vol. 56, pp. 307–314 (2000)
Jeong, J., Sekiguchi, K. and Sakamoto, K., “Photochemical and Photocatalytic Degradation of Gaseous Toluene Using Ahort-Wavelength UV Irradiation with TiO2 Catalyst: Comparison of Three UV Sources,” Chemosphere, Vol. 57, pp. 663–671 (2004).
Jiang, D., Zhao, H., Jia, Z., Cao, J. and John, R., “Photoelectrochemical Behaviour of Methanol Oxidation at Nanoporous TiO2 Film Electrodes,” J. Photochem. Photobiol. A-Chem., Vol. 144, pp. 197–204 (2001).
Kim, S.B. and Hong, S.C., “Kinetic Study for Photocatalytic Degradation of Volatile Organic Compounds in Air Using Thin Film TiO2 Photocatalyst,” Appl. Catal. B., Vol. 35, pp. 305–315 (2002).
Kim, S.B., Hwang, H. T. and Hong, S.C., “Photocatalytic Degradation of Volatile Organic Compounds at the Gas–solid Interface of a TiO2 Photocatalyst,” Chemosphere, Vol. 48, pp. 437–444 (2002).
Larson, S.A., Widegren, J.A. and Falconer, J.L., “Transient Studies of 2-Propanol Photocatalytic Oxidation on Titania,” J. Catal., Vol. 157, pp. 611–625 (1995).
Li, X. Z. and Liu, H. S., “Development of an E-H2O2/TiO2 Photoelectrocatalytic Oxidation System for Water and Wastewater Treatment,” Environ. Sci. Technol., Vol. 39, pp. 4614–4620 (2005).
Li, X.Z., Li, F.B., Fan, C.M. and Sun, Y.P., “Photoelectrocatalytic Degradation of Humic Acid in Aqueous Solution Using a Ti/TiO2 Mesh Photoelectrode,” Water Res., Vol. 36, pp. 2215–2224 (2002).
Liu, Y., Xie, C., Li, H., Chen, Liao, Y. and Zeng, D., “Low Bias Photoelectrocatalytic (PEC) Performance for Organic Vapour Degradation Using TiO2/WO3 Nanocomposite,” Appl. Catal., B., Vol. 102, pp. 157–162 (2011).
Liu, Y., Xie, C., Zou, T., Li, J., Chen, H. and Zeng, D., “Applied Low Bias with High Frequency for Enhancing Mineralization Ability of WO3 as Visible-Light-Driven Photocatalyst in Gas Phase,” Catal. Commun., Vol. 16, pp. 180–183 (2011).
Liu, Z., Zhang, X., Nishimoto, S., Jin, M., Tryk, D.A., Murakami, T. and Fujishima, A., “Highly Ordered TiO2 Nanotube Arrays with Controllable Length for Photoelectrocatalytic Degradation of Phenol,” J. Phys. Chem. C, Vol. 112, pp. 253–259 (2008)
Ma, C. M., Ku, Y., Kuo, Y. L., Chou, Y. C. and Jeng, F. T. , “Effects of Silver on the Photocatalytic Degradation of Gaseous Isopropanol,” Water Air Soil Pollut., Vol. 197, pp. 313–321 (2008).
Ma, C.M. and Ku, Y., “Photocatalytic Oxidation of Gaseous Trichloroethylene by UV/TiO2 Process,” React. Kinet. Mech. Catal., Vol. 89, pp. 293–301 (2006).
Ma, Y., Qiu, J.b., Cao, Y.A., Guan, Z.S. and Yao, J.N., “Photocatalytic Activity of TiO2 Films Grown on Different Substrates,” Chemosphere, Vol. 44, pp. 1087–1092 (2001).
Mo, J., Zhang, Y. and Xu, Q., “Effect of Water Vapor on the By-Products and Decomposition Rate of PPb-Level Toluene by Photocatalytic Oxidation,” Appl. Catal., B., Vol. 132, pp. 212–218 (2013).
Mo, J., Zhang, Y., Xu, Q., Lamson, J.J. and Zhao R., “Photocatalytic Purification of Volatile Organic Compounds in Indoor Air: A Literature Review,” Atmos. Environ., Vol. 43, pp. 2229–2246 (2009).
Obee, T.N. and Hay, S.O., “Effects of Moisture and Temperature on the Photooxidation of Ethylene on Titania,” Environ. Sci. Technol., Vol. 31, pp. 2034–2038 (1997).
Sawada, S., Yamaki, T., Maeno, T., Asano, M., Suzuki, A., Terai, T. and Maekawa, Y., “Solid Polymer Electrolyte Water Electrolysis Systems for Hydrogen Production Based on Our Newly Developed Membranes, Part I: Analysis of Voltage–Current Characteristics,” Prog. Nucl. Energy, Vol. 50, pp. 443–448 (2008)
Shang, J., Xie, S., Zhu, T. and Li, J., “Solid-State, Planar Photoelectrocatalytic Devices Using a Nanosized TiO2 Layer,” Environ. Sci. Technol., Vol. 41, pp. 7876–7880 (2007).
Shang, J., Zhang, Y., Zhu, T., Wang, Q. and Song, H., “The Promoted Photoelectrocatalytic Degradation of Rhodamine B Over TiO2 Thin Film Under the Half-Wave Pulsed Direct Current,” Appl. Catal. B., Vol. 102, pp. 464–469 (2011).
Vildozo, D., Ferronato, C., Sleiman, M. and Chovelon, J.M., “Photocatalytic Treatment of Indoor Air: Optimization of 2-Propanol Removal Using a Response Surface Methodology (RSM),” Appl. Catal. B., Vol. 94, pp. 303–310 (2010).
Vinodgopal, K., Hotchandani, S. and Kamat P.V., “Electrochemically Assisted Photocatalysis1: TiO2 Particulate Film Electrodes for Photocatalytic Degradation of 4-Chlorophenol,” J. Phy. Chem., Vol. 97, pp. 9040-9044 (1993).
Vinodgopal, K., Stafford, U., Gray, K.A. and Kamat, P.V., “Electrochemically Assisted Photocatalysis 2: The Role of Oxygen and Reaction Intermediates in the Degradation of 4-Chlorophenol on Immobilized TiO2 Particulate Films,” J. Phy. Chem, Vol. 98, pp. 6797-6803 (1994).
Waldner, G., Pourmodjib, M., Bauer, R. and Spallart, M.N., “Photoelectrocatalytic Degradation of 4-Chlorophenol and Oxalic Acid on Titanium Dioxide Electrodes,” Chemosphere, Vol. 50, pp. 989–998 (2003).
Wang, W. and Ku, Y., “Photocatalytic Degradation of Gaseous Benzene in Air Atreams by Using an Optical Fiber Photoreactor,” J. Photochem. Photobiol. A-Chem., Vol. 159, pp. 47–59 (2003)
Xu, W. and D. Raftery, “Photocatalytic Oxidation of 2-Propanol on TiO2 Powder and TiO2 Monolayer Catalysts Studied by Solid-State NMR,” J. Phys. Chem. B, Vol. 105, pp. 4343-4349 (2001).
Xu, Y., Xu, W., Huang, F. and Wei, Q., “Preparation and Photocatalytic Activity of TiO2-Deposited Fabrics,” Int. J. Photoenergy, Vol. 2012, pp. 1–5 (2012).
Zhang, J., Tang, Y., Song, C., Xia, Z., Li, H. and Wang, H., “PEM Fuel Cell Relative Humidity (RH) and Its Effect on Performance at High Temperatures,” Electrochim. Acta, Vol. 53, pp. 5315–5321 (2008).
Zhao, X. and Zhu, Y., “Synergetic Degradation of Rhodamine B at a Porous ZnWO4 Film Electrode by Combined Electro-Oxidation and Photocatalysis,” Environ. Sci. Technol., Vol. 40, pp. 3367–3372 (2006).