| Abstract: | 異質半導體光觸媒主要是藉由兩種不同半導體界面，來提升單一半導體光觸媒的光催化性能，因異質結能有效增加電子電洞對的分離能力，降低複合率。在本研究中藉由sol-gel法成功合成了YFeO3/CeO2複合材料，且提升了YFeO3的光催化特性。在瞬時光電流檢測中，YFeO3/30%CeO2複合材料能將YFeO3的光電流密度從12.8 µA/cm2 增加為156.3 µA/cm2，提升大約12倍，也有著比純CeO2好的光電催化特性。此外，在其他比例下的複合材料的光電流密度也會隨著CeO2含量增加，可得知YFeO3/CeO2異質結確實能提升光電化學表現。
而在本研究也進行了光催化降解RB5和光電催化降解RB5的比較。在光催化系統中。YFeO3、CeO2、YFeO3 /30 %CeO2光降解效率分別18.5 %、37.4 %和48.0 %；而在光電催化降解系統中，YFeO3、CeO2和YFeO3 / 30%CeO2光電催化降解RB5效率為32.6%、47.9 %和75.6 %，從結果可知藉由外加電壓的幫助，能有效地將電子傳輸於對電極，降低電子電洞對複合率，使降解效率大大提升。最後將YFeO3、CeO2分別進行了Mott-Schottky測量，得知其平帶位置。再經由計算得知YFeO3和CeO2的導帶位置和價帶位置，推論出了YFeO3/CeO2複合材料光催化降解RB5反應機制。
;Heterogeneous semiconductor photocatalysts mainly use two different semiconductor interfaces to improve the photocatalytic performance of a single semiconductor photocatalyst, because the heterojunction can effectively increase the separation ability of electron-hole pairs and reduce the recombination rate. In this study, YFeO3/CeO2 composites were successfully synthesized by the sol-gel method, and the photocatalytic properties of YFeO3 were improved.
In the instantaneous photocurrent detection, the YFeO3/30%CeO2 composite can increase the photocurrent density of YFeO3 from 12.8 µA/cm2 to 156.3 µA/cm2, an increase of about 12 times, and it also has better photocatalytic properties than pure CeO2. In addition, the photocurrent density of the composites at other ratios also increases with the CeO2 content, indicating that the YFeO3/CeO2 heterojunction can indeed improve the photoelectrochemical performance.
In this study, the photocatalytic degradation and the photoelectrocatalytic degradation of RB5 were also compared. In the photocatalytic system, the photodegradation efficiencies of YFeO3, CeO2, and YFeO3/30 %CeO2 were 18.5%, 37.4% and 48.0%, respectively. On the other hand, in the photoelectrocatalytic degradation system, the degradation efficiencies of YFeO3, CeO2, YFeO3/30 %CeO2 for RB5 were 32.6%, 47.9% and 75.6%, respectively. It can be seen from the results that with the help of the applied voltage, electrons are effectively transferred to the counter electrode, the recombination rate of electron-hole pairs can be reduced, and the degradation efficiency can be greatly improved. Finally, the Mott-Schottky measurements were performed on YFeO3 and CeO2, respectively, and the position of the flat band was obtained. Then the conduction band position and valence band position of YFeO3 and CeO2 were obtained by calculation. Furthermore, the mechanism of photocatalytic degradation of RB5 by YFeO3/CeO2 composites was deduced. |
