本研究利用紫外光發光二極體為光源，以間歇照光二氧化鈦光觸媒，提升水溶液中二氧化碳還原效率、光子利用率以及光量子產率。透過BET、XRD、SEM、UV-Vis DRS和界達電位，進行光觸媒的物化特性之分析。在連續操作照光的實驗中，探討各種實驗操作變因(如：水溶液pH值、氧化鎳添加量、初始二氧化碳濃度和光強度)對於光還原二氧化碳之影響。對於間歇照光操作下的實驗，探討照光時間、暗時間、佔空比以及照光週期等操作變因對於光還原二氧化碳的影響。
研究結果顯示，以過量的氧化鎳添加量進行改質的光觸媒二氧化鈦，會導致光還原效率下降。在總照光時間為60分鐘時，相較於連續照光，利用間歇照光可以有效提升光還原二氧化碳的還原效率、光子利用率、光量子產率以及甲醇產率。間歇操作可以藉由控制暗期補充觸媒表面上反應物，利用控制光期給予適量光能，進而減少電子電洞對的再結合。
相較於佔空比為1.00 (連續照光)，當光觸媒程序操作於佔空比為0.09(間歇照光)，甲醇產率從807提升到830 umol gcat–1 hr–1 。此外，在連續照光以及間歇照光下操作之光觸媒還原二氧化碳行為符合Langmuir-Hinshewood動力模式。在間歇照光下進行的實驗，能源使用明顯減少，達到節能的效果。

The application of periodic illumination with UV-LED for the enhancement of reduction efficiency, photonic efficiency and quantum yield in the process for photocatalytic reduction of CO2 was investigated. The characterizations of photocatalyst were analyzed by Brunauer-Emmett-Teller surface area measurement (BET), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), UV-Vis diffuse reflectance spectra (UV-Vis DRS) and zeta potential. For the experiment conducted at continuous illumination, the effect of solution pH, different NiO dosage, initial CO2 concentration and light intensity on CO2 reduction were studied in a batch reactor. The effect of periodic illumination, duty cycle and periodic frequency on photocatalytic reduction of CO2 in the aqueous phase was discussed by UV-LED/TiO2 process with the operation of periodic illumination.
The result showed that excessive NiO dosage would lead to a decrease in photocatalytic performance. The reduction efficiency, photonic efficiency, quantum yield and yield rate were enhanced when the experiment operated with periodic illumination in the total illumination time 60 minutes. The application of periodic illumination could provide the time for the replenishment of surface coverage and result in a decrease of carrier recombination. The yield rate increased from 807 to 830 umol gcat–1 hr–1 for the experiments operated at the duty cycle from 1.00 (continuous illumination) to 0.09 (periodic illumination). Moreover, the photocatalytic reduction of CO2 by UV-LED process under continuous and periodic illumination could be well modeled by the Langmuir-Hinshewood kinetic equation. The electric energy saving increased significantly for the experiment conducted at periodic illumination.

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