本研究是利用製成簡單的陽極氧化法製備n型半導體氮化鉭薄膜，能隙大小約為2.0 eV，適合作為吸收可見光的半導體材料以及光分解水的陽極電極。經由X光繞射儀以及掃描式電子顯微鏡的分析，氮化鉭為斜方晶相的結構，大小約為20~50 nm 的奈米顆粒，顆粒之間有相互交連而形成孔洞的結構。藉由浸泡氮化鉭薄膜於硝酸鈷溶液中，經過高溫氮化反應後，可在薄膜上形成p型的氮化鈷。並利用Mott-Schottky分析、UV-Visble及循環伏安法鑑定了氮化鉭和氮化鈷的半導體特性，包括有導帶、價帶以及費米能階的位置。
由研究結果顯示，氮化鈷負載於氮化鉭薄膜上所形成的p-n界面可以提升氮化鉭薄膜的光電化學性質。在AM1.5的太陽模擬光照射下，0.5M的氫氧化鉀水溶液中，可於偏壓0.5V vs. Ag/AgCl下有2.5 mA/cm2的光電流應答，比相同條件下單純氮化鉭薄膜的光電流30μA/cm2來的更為優異。經交流阻抗和IMPS(Intensity Modulated Photocurrent Spectroscopy)的分析也發現，利用此p-n界面，可以改善電荷分離的效果，減少再結合反應的發生，讓電子可以快速的通過薄膜傳到電極，使得在光電化學反應的效率能夠大幅提升。
另外，本研究將二極式光電極系統結合氣相層析儀，於300W氙燈的可見光(λ>420nm)照射下，施加固定電位所得到光電流對時間應答的曲線，利用法拉第定律求得理論的產生氣體量；而真實的氣體產生量，則藉由氣相層析儀的量測而得到，透過此系統，也能證實所得之光電流為照光後分解水時所產生之電流應答。

In the present work, a n-type semiconductor tantalum nitride(Ta3N5) film is fabricated by anodization. Ta3N5 with a band gap of 2.0 eV, which can absorb visible light and is suitable to be a good photoanode. From XRD and SEM analysis, which can know that Ta3N5 belong to orthorhombic phase, has the porous structure and the particle size of about 20~50 nm. In addition, immersing the Ta3N5 film in Co(NO3)2 solution then take it to nitride, can form a p-type cobalt nitride(Co5.47N) on it. By using Mott-Schottky, UV-Vis absorption and CV to check their conduction band, valance band and fermi level.
With the p-n interface on Co5.47N-Ta3N5 film, it can greatly enhance the performance for photoelectrochemical water oxidation. Under AM 1.5 G simulated sunlight illumination, the photocurrent density of Co5.47N-Ta3N5 can reach 2.5mA/cm2, which is more larger than 30μA /cm2 of bare Ta3N5 film at 0.5V vs. Ag/AgCl in 0.5M KOH solution . From EIS and IMPS analysis, it is established that the intimate contact between Co5.47N and Ta3N5 can improve the electron-hole separation, decrease the recombination and reduce the resistance to the transport of electrons.
By combining the photoelectrode system with GC, it can calculate the theoretical electron moles from current-time curve and detect the real gas evolution from GC at the same time, under 300W Xe lamp visible light illumination, at fixed potential. Through this system, which can prove that the water splitting gas evolution is form the photocurrent response.

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