使用太陽能分解水乃是一種替代能源方案的方法，而其中光電化學電池為具有非常高潛力的方法，在所有光電極材料中BiVO4光電極擁有需多光電化學電池優良的特性，例如:符合水分解所需的價帶邊界範圍、狹小的能隙、在中性電解液中具有良好的穩定性等，但BiVO4本身仍具有一項非常大的缺點需要改進，就是與水間的動力學效應非常差，因此本實驗致力於改善這項缺點。

在本實驗中選用光化學有機金屬沉積法(Photochemical metal organic deposition, PMOD)，做為將金屬氧化物FeOx覆蓋於BiVO4光電極的方法，此方法不需要使用高溫、高壓及冗長的加熱時間，因此不會造成過多的能量消耗。從本實驗結過中可以發現，當覆蓋濃度太低時能夠提供的觸媒活性點相對較少，但當濃度太高時會產生光遮蔽作用，因此使用重量百分濃度為5 wt% 的iron (Ⅲ)2-ethylhexanoate製備FeOx時具有最好的效果，在施加偏壓為1.3 V vs. RHE時，光電流密度可達1.1 mA/cm2，大於原先BiVO4光電極的2.2倍，並且反應起始電位也從原先的0.65 V降到0.3 V vs. RHE，同時發現當使用PMOD法覆蓋FeOx於BiVO4光電極表面時具有保護電極表面的作用，透過計時電位法測定將反應電流固定在0.3 mA下維持2 h，其單一BiVO4光電極之電壓上升幅度約為5 wt%的iron (Ⅲ)2-ethylhexanoate塗佈所製備的FeOx/BiVO4光電極上升幅度的12倍，最後由吸收光光電子轉化效率(APCE)測試結果中得知，當入色光波長為445 nm時使用5 wt%的iron (Ⅲ)2-ethylhexanoate塗佈所製備的FeOx/BiVO4光電極其APCE效率值可達到45.5%。

Serving as a photoelectrochemical water splitting material, monoclinic BiVO4 satisfies many requirements for a highly active photoanode, such as moderate band gap (2.55eV), favorable chemical and photoelectrochemical stability, low overpotential for oxygen evolution reaction. However, it suffers from a key drawback: the slow kinetics of photon-generated charge carrier reacting with water molecules. Therefore, a layer of metal oxide oxygen evolution reaction catalyst, preparing by photochemical metal-organic deposition (PMOD), was introduced on the BiVO4 photoanode surface to enhance the efficiency of photoelectrochemical water splitting reaction.

In this study, amorphous iron oxide catalyst was deposited on the BiVO4 photoanode. It is found that there is an optimal thickness for the metal oxide catalyst due to the competition between the light sheltering effect of this catalyst layer and the amount for catalyst for reaction. With the introduction of this catalyst layer, the photocurrent density increases about two times, i.e. from 0.5 mA/cm2 for BiVO4 alone to 1.2 mA/cm2 for FeOx/BiVO4 at 1.3 V vs. RHE.

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