Titanium dioxide based materials for solar light driven hydrogen production
Li Cheng Kao1, Sofia Ya Hsuan Liou1*
1Department of Geosciences, National Taiwan University, Taipei, Taiwan
* Presenter:Sofia Ya Hsuan Liou, email:yhliou@ntu.edu.tw
Finding sustainable alternative energy sources has become necessary because of the increasing cost of fossil fuels and the drastic effects of global climate change. In 1972, Fujishima and Hondal reported that TiO2 as a semiconductor photoanode can split water into hydrogen and oxygen; this reaction is caused by UV light illumination. Solar light and water are abundant and sustainable resources on the earth. To combine these two abounding resources, using solar light to split water and obtain hydrogen would be an environmentally friendly method to produce sustainable and clean energy. One dimensional structure provides easy access of electron transport to the surface, which permit light scattering and enhances photocatalytic activities. TiO2 with 1 dimensional nanostructured arrays have extensive applications for photovoltaic and PEC hydrogen generation. A transparent, large-scale, free-standing 1D mixed phase TiO2 nanorod array films are successfully synthesized by adding solid-state Ti foils as precursors. The dynamic changes in the acidity and the titanium and chloride ion concentrations, as well as their photocatalytic performances, are investigated. This method is the first approach to synthesize densely packed mixed phase TiO2 nanorod array films, and has opened a promising route for tuning the reaction conditions to fabricate materials with different Ti growth units. A doublesided tandem structure for quantum dot (QD) cosensitized photoelectrodes with excellent solar PEC hydrogen generation is presented in this study. Given the transparent substrates, a double-sided tandem structure could be achieved for photoelectrode design. These two different QD, Cd and CdSe were sequentially deposited on TiO2 to form a cosensitized tandem structure. The cosensitized double-sided structure exhibited superior ability compared with single or cosensitized one-sided photoelectrode. The double-sided CdS and CdSe cosensitized 1D TiO2 photoelectrode exhibited the highest solar-to-hydrogen conversion efficiency of 2.78% and pronounced enhancement of simulated photoconversion efficiency. This success in fabricating a double-sided tandem structure 1D TiO2 photoelectrode provides the opportunity for composite material design based on different band gaps, and this photoelectrode could be applied to other PEC applications.

Keywords: Titanium Dioxide, Nanorod, Photocatalytic, Hydrogen generation