Eumelanin-Sensitized TiO2 Photoelectrode and its Application in Hydrogen Generation by Photo-catalytic Water Splitting

• Main Authors: Hung,Anhao, 洪安豪
• Other Authors: Lin,Jiunnyuan
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/64818424137475007871

碩士 === 國立中正大學 === 物理學系暨研究所 === 99 === In this thesis, we utilize the eumelanin-sensitized TiO2 photoelectrode in generation of hydrogen by photo-catalytic water splitting. TiO2 photoelectrode is first fabricated by using Sol-Gel and Doctor blade methods, and then sensitized by electropolymerized eumelanin film. All the photoeletrodes is characterized by a home-made photocurrent measurement system, and then used in another home-made hydrogen collection system for measuring hydrogen production rate and efficiency. TiO2 photoelectrode only absorbs ultraviolet light energy, and ultraviolet radiation only accounts for 5% of the total solar spectrum. Therefore, a sensitizer with broadband absorption is often used for extending the photoelectrode absorption spectrum to the visible region. Eumelanin is known as a broadband absorber from ultraviolet to infrared light, and is used as a photosensitizer for TiO2 photoelectrode in this experiment. It is found that the photoelectrode indeed absorbs more radiation energy in the visible region with the eumelanin sensitizer. The photocurrent conversion efficiency of TiO2 photoelectrode is about 0.07% at the optimal condition, while that of eumelanin-sensitized photoelectrode is only 0.007%, which is one order of magnitude smaller. The reason for low efficient in sensitized electrode may be due to the poor control capability in eumelanin deposition. Eumelanin cannot be uniformly covered on the TiO2 surface with single layer by using electropolymerization method and also cannot have good contact with TiO2 molecules, making photoelectrons substantially lost after transportation in eumelanin and the junction between eumelanin and TiO2. The hydrogen production is also successfully measured with hydrogen collection system. The hydrogen production rate is only qualitatively determined with current setup.