本研究利用溶膠凝膠法以異丙氧鈦為起始物，在低溫下(< 80 ℃)製作出高穿透率的二氧化鈦銳鈦礦相薄膜於玻璃基板上。之後，在局部二氧化鈦薄膜表面沉積金顆粒。為增進光觸媒作用，於局部金/二氧化鈦表面化學吸附苯乙硫醇自組裝單分子層。在局部二氧化鈦薄膜表面，選擇三種不同比率的沉積金顆粒的覆蓋面積，約為3.77 %、15.58 %、以及41.97 %。金局部覆蓋於二氧化鈦表面乃考量到外露二氧化鈦的表面積。

利用低掠角X光繞射分析儀以及拉曼散射光譜儀分析薄膜晶體結構，以掃描式電子顯微鏡以及原子力顯微鏡分析薄膜表面形貌；以X光光電子能譜儀分析薄膜表面化學組成，以歐傑電子能譜儀分析薄膜深度分析，最後以亞甲基藍降解試驗評估光觸媒薄膜的效能。外露二氧化鈦表面積及苯乙硫醇自組裝單分子層的吸附量會受到金的覆蓋率改變而影響。

在金/二氧化鈦的試片，其光觸媒效能測試結果依覆蓋面積比率表示為15.58 % > 41.97 % > 3.77 %，適度的金覆蓋面積可預期地減少電子與電洞對的合併機率。另一方面，苯乙硫醇自組裝單分子層吸附於金/二氧化鈦表面，能增強光觸媒效果，依序為：3.77 % >15.58 % > 41.97 %。此顯示，苯乙硫醇自組裝單分子層吸附於金/二氧化鈦表面不同於金在二氧化鈦銳鈦礦相薄膜。

苯乙硫醇自組裝單分子層吸附愈多，受光激發出電子，電子往外傳遞給O2時生成．O2-與．OH反應，造成亞甲基藍的初始降解反應被阻斷；或是．O2-遷移到與表面電洞復合，藉由被吸附而占據二氧化鈦的活性位置，如：缺陷及氧空位，此將致使．OH的生成量減少或光觸媒效果下降。另外，苯乙硫醇將電子回傳給金時，造成金吸引二氧化鈦電子的趨動力下降，減低捕捉二氧化鈦自由電子的能力，增加電子電洞對復合的機率。經評估後，以苯乙硫醇於3.77 %金之二氧化鈦表面為最佳光觸媒反應系統，比二氧化鈦銳鈦礦相薄膜效率高約18.7 %。

High transparency TiO2–anatase thin film on glass substrate was prepared by the sol-gel method with the precursor of titanium isopropoxide (TTIP) under low temperature (< 80 ℃). Subsequently, a part of TiO2–anatase thin film was deposited with Au particles. To enhance the photo-catalytic effect, self assembled phenylethyl mercaptan monolayer was chemically adsorbed on the as-prepared partial Au/TiO2 thin film, chosen with three different Au-coverage areas, 3.77, 15.58, and 41.97 %. Au was partially deposited upon TiO2-anatase thin film for the consideration of the exposure of TiO2 surface.

GIXRD and Raman spectrometer was employed for characterizing the crystalline structure of TiO2, while SEM and AFM for measuring surface morphologies. XPS was utilized for analyzing chemical structures on the as-prepared surfaces, while AES for profiling depths. The photo-catalytic effect was then evaluated by the TiO2-anatase induced degradation of methylene blue. The exposed TiO2 surface area and the quantity of the adsorbed phenylethyl mercaptan were varied with Au coverage rates.

Photo-catalytic activities of Au/TiO2-anatase thin film were enhanced by the sequence of Au coverage areas: 15.58 % > 41.97 % > 3.77 %. An appropriate coverage of Au upon TiO2-anatase thin film was thus anticipated to reduce the recombination probability of their electron-hole pairs. On the other hand, photo-catalytic activities of the chemisorbed phenylethyl mercaptan/Au/TiO2 were enhanced by the sequence of Au coverage upon TiO2-anatase thin film: 3.77 % > 15.58 % > 41.97 %. It reveals that the photo-catalytic contribution of phenylethyl mercaptan on Au/TiO2 differs from that of Au upon TiO2-anatase thin film.

As increased the adsorbed quantity of phenylethyl mercaptan monolayer, the UV-excited electrons transferring to O2, forming．O2-, and reacting with．OH, which result in blocking the initial degradation of methylene blue. It is also probable that．O2- species move forward to TiO2 surface and recombine with photo-holes or adsorb on the surface containing TiO2 active sites such as defects and oxygen vacancies. That will lead to decrease the formation of．OH or therefore the photo-catalytic effect. In addition, it is assumable that the electrons returning to Au will cause the degradation of driving force to capture free electrons from TiO2. As a result, the recombination of electron-hole pairs tends to be increased. An optimized photo-catalytic system is thus suggested by the structure of phenylethyl mercaptan/3.77 % Au/TiO2-anatase thin film. Potentially about 18.7 % efficiency is increased as compared with the as-deposited TiO2-anatase thin film.

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