| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 97 === These studies utilize the method of chemical bath deposition (CBD) to assemble, CdS and CdSe onto porous TiO2 films as sensitizer for photoelectrochemical hydrogen generation. The sensitizer incorporated amount and co-sensitized effect on photoelectrochemical conversion efficiency were discussed in this study. The results show that the CdS/CdSe co-sensitized photoelectrode has not only a complementary effect in light harvest and the cascade structure, TiO2/CdS(4)/CdSe(4), but leads to a stepwise structure of band-edge levels which is advantageous to the electron injection and hole-recovery of the system. The energy conversion efficiency (ECE) achieved by the TiO2/CdS(4)/CdSe(4) electrode under illumination (AM1.5, UV cut-off, 100 mW/cm2) is 7.4%. Zinc Sulfide (ZnS) was further deposited as passivation layer to improve the photoelectrode stability and reduce leakage current. The corresponding hydrogen evolved rate measured for the TiO2/CdS(4)/ CdSe(4)/ZnS electrode is 210 µmol．cm-2．h-1. Further, thermal-treatment process was used to improve TiO2/sensitizer interface and increase sensitizer crystallinity, the electron transfer ability of photoelectrodes and decrease the electrode defects. At the temperature of 300℃ and 150℃, the electrode TiO2/CdS(4)300℃/CdSe(4)150℃ had the highest photocurrent density about 17 mA/cm2 and ECE is 10.6%.
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