本次碩論主題是透過光電化學系統產生氫氣與甲酸等經濟能源，選用的光電陽極為n型氮化鎵(n-GaN)，由於此半導體具有合適的能帶位置，足以匹配水分解所需的氧化還原電位也能將二氧化碳還原成甲酸，且n-GaN本身化學穩定性要比其餘傳統三五族半導體(GaP、GaAs…等)來得高，另外作為直接能隙半導體具有不錯的光吸收特性，也有文獻指出n-GaN確實能實行零偏壓水分解反應。
但由於n-GaN自身的分解電位介於價帶與導帶之間，因此在水分解的同時，也會遭遇光腐蝕的情形，此篇碩論即是在探討如何利用鈷(Cobalt)的相關化合物來鈍化表面，減少光腐蝕的發生，同時降低陽極反應的過電位，提升載子動力幫助載子在液半接面的傳輸，如此便能帶來效率上的提升以及增加基板的穩定性。
但後續發現儘管Co(OH)2具有上述優異的特性，但由於其本身若處在中、酸性電解液會出現不穩定的結果，可以透過穩定性量測發現Co(OH)2會逐漸脫離n-GaN表面。為了解決此現象，嘗試在進行PEC實驗前利用高溫通氧退火來將Co(OH)2轉變成更穩定的氧化鈷(Co3O4)，期望在保留上述優良特性的同時，也能大大的提升穩定性。

In recent years, hydrogen has attracted much attention as a renewable energy source. However, steam reforming, the main method of hydrogen production at present, which produces carbon dioxide while in the process of producing hydrogen. Therefore, many studies devoted to study photoelectrochemical hydrogen production as an alternative. Among them, n-GaN crosses the redox potential of water because of its energy band position, so it is suitable for solar water splitting reaction. However, the n-GaN based electrode encounters the problem of photocorrosion while in the experiment. In this study, we focused on depressing the photocorrosion by using the catalyst Co(OH)2 and Co3O4 respectively. Interestingly, these two catalysts can not only slow down the photocorrosion, but also decrease the overpotential of water oxidation. Allowing the water splitting reaction to be done under a lower applied bias and improving hydrogen production efficiency.

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