摘要
利用光電化學電池(PEC cell)系統分解水產生氫氣，為提供乾淨且可再生之能源的一種新穎方法。由於太陽光中約有45%屬於可見光波段，PEC系統中之光觸媒材料，也以朝製備可見光應答型光觸媒之方向最為蓬勃發展。和粉體光觸媒相較下，以半導體薄膜作為光電極，利用PEC系統產氫的二大優點分別是：1. 可直接在陰極及陽極分別收集氫氣和氧氣，無須另外分離；2. 當光催化活性衰退時便於回收。在目前發現之各種半導體光觸媒薄膜之中，又以硫化物系列半導體之光催化性能優於氧化物系列半導體。
本研究製備保護層材料以兩部分為主：第一部分，先以化學水浴沉積法(CBD)於氧化銦錫(ITO)導電玻璃基材表面製備銀銦硫(Ag-In-S)三元半導體薄膜，並藉由改變[Ag]/[In]之莫耳數比，利用低掠角XRD (GIXRD）分析，可分別得到AgInS2、AgIn5S8與AgInS2/AgIn5S8之混相薄膜結構。以三極式光電化學系統配合恆電位儀量測光電流值，在光強度為100 mW/cm2之可見光照射下，以AgInS2/AgIn5S8之混相薄膜結構，可得到之最大光電流值約為10 mA/cm2 at bias 1V vs. SCE ，而將此光電極薄膜置於犧牲試劑中進行穩定性測試，於照光一段時間後會發生光侵蝕的現象，並導致光電流之衰退。因此，本研究於第二部分即為了延長此銀銦硫光觸媒薄膜之使用壽命，而於此薄膜表面鍍一層保護層材料，最後選用硫化鋅為此保護層之材料，並分別使用濺鍍法與化學水浴法製備硫化鋅之半導體薄膜，並藉由調整硫化鋅之薄膜厚度，量測其物理、光學與光電流等特性，以篩選出最佳參數，最後測試其光電化學穩定性。

ABSTRACT
Hydrogen production by water splitting with photoelectrochemical cell (PEC cell) is one of novel ways to provide clean and renewable energy. Due to that visible light accounts for about 45% in sunlight, the visible light responded photocatalyst materials have been developed widely. Thin film as electrode in photoelectrochemical cell take advantage of that no need to separate hydrogen and oxygen and easy to recover, compared to powder materials. Among them, the performance of sulfide semiconductor is better than that of oxide semiconductor.
In this study, Ag-In-S ternary semiconductor thin film prepared by chemical bath deposition (CBD) is the mixture phase of AgInS2/AgIn5S8, deposited on the surface of indium tin oxide conductive glass. The photoelectric conversion efficiency could be estimated with a photocurrent density test by a three-electrode system and a potentiostat. Under the visible light irradiation with intensity of 100 mW/cm2, the photocurrent density could be up to about 10 mA/cm2. However, photocorrosion of the thin film occurs in sacrificial reagents as electrolyte after irradiation for a while, and results in a photocurrent decay. To enhance the durability of the thin film, we attempts to coat a zinc sulfide (ZnS) film, which has a higher stability and absorbs no visible light, as a protective layer on the surface of Ag-In-S film. ZnS protective layer is prepared by sputtering and CBD respectively in this study. Thus, the effect of photocorrosion in Ag-In-S thin film could be reduced. The modified photocatalyst thin film with the protective layer shows an obvious enhancement in the durability without a serious decay in photocurrent.

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