光電化學水分解系統被視為一可持續產生氫氣的環境友善製程，然而許多銅基光陰極因電化學腐蝕問題而面臨了極大的水溶液不穩定性。因此，利用物化性相對穩定的二氧化鈦進行電極修飾，是提高光電極穩定性最有用的策略之一。
本研究演示了一種簡單且可調控厚度的保護層形成方法，因生物礦化法製程僅需利用材料本身的靜電力吸引進行逐層自組裝，因此適合應用於銅基光陰極的保護層修飾。眾所周知，氧化亞銅面臨著嚴重的電化學腐蝕問題，而生物礦化法所形成的二氧化鈦保護層可以有效的防止電解液與材料直接接觸，降低了氧化亞銅因電化學腐蝕所產生的電流下降；在退火製程的選擇上，我們分別使用管狀爐進行傳統退火和家用微波爐進行混合微波退火，因微波退火條件於大氣環境，氧原子除了參與有機物的熱裂解，也會與氧化亞銅反應形成氧化銅。
在第一部分中，本研究利用化學腐蝕與電化學方法，探討了生物礦化法與管狀爐退火產生的TiO2 保護層對於電極穩定性的提升。在第二部份我們利用生物礦化法與混合微波退火修飾了平面結構氧化亞銅，修飾後的平面結構氧化亞銅在0.2 V (vs. RHE)偏壓下照光一小時後，其光電流衰減大幅降低；且在循環伏安法中的腐蝕電流也隨之降低，顯示光電化學穩定性的提升。本研究利用穿透式電子顯微鏡證實了TiO2保護層的存在；此外，由光激發光譜可以觀察出修飾後的電極具有低缺陷且光生載子複合降低的特性，與莫特-肖特基結果中的載子濃度上升可以相呼應。此種方法為價格昂貴的原子層沉積技術提供了一個有前景的替代方法。

Photoelectrochemical(PEC) water splitting system is regarded as an environmentally friendly process for sustainable hydrogen production. However, many copper-based photocathodes suffer from severe instability due to electrochemical corrosion issue. Therefore, modification of chemically and physically stable materials, such as TiO2, is one of the most useful strategies to improve the stability of photoelectrodes.
In this study, we demonstrate a simple and thickness adjustable method of protection layers formation. The biomineralization technique only needs the electrostatic attraction between materials for layer-by-layer self-assemble, so it can be easily applied to the protection layers modification of copper-based photocathode. As we all know, cuprous oxide faces severe electrochemical corrosion issue. The titanium dioxide protection layers formed by biomineralization can efficiently prevent the electrode from contacting the electrolyte directly and reduce the current losses from electrochemical corrosion. In the selection of the annealing process, we use tube furnace to perform a conventional annealing process and household microwave oven to perform a hybrid microwave annealing, respectively. Because of the atmospheric microwave annealing condition, the oxygen atoms are not only involved in the pyrolysis of organic compounds but also react with cuprous oxide to form cupric oxide.
In the first part, chemical corrosion and electrochemical methods were used to study the electrode stability improvement of TiO2 protection layers formed by the biomineralization method and a tube furnace annealing process. In the second part, we modified the planar Cu2O by the biomineralization method and a hybrid microwave annealing process. The photocurrent reduction of modified Cu2O greatly reduces after one hour irradiation at a 0.2 V(vs. RHE) bias and the corrosion current in cyclic voltammetry results is also reduced. In this study, the transmission electron microscope(TEM) is used to confirm the existence of TiO2 protection layers. In addition, low defect states and the reduction of photogenerated carrier recombination of modified Cu2O can be observed from the photoluminescence spectroscopy(PL), which are consistent with the increase of carrier concentration in Mott-Schottky results. This developed technique offers a promising alternative way to expensive atomic layer deposition technique.

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