Development of anion-doped semiconducting oxides for solar hydrogen conversion
The photoelectrochemical production of hydrogen from water using solar energy has drawn considerable attention due to the importance of using hydrogen as a clean and renewable source. Wide band-gap semiconductors are the most promising materials for this purpose due to their good stability and catalytic activity; however, their wide band gap corresponds to the absorption of UV light only. The focus of this thesis is on the improvement in semiconductor metal oxides by anion doping. In particular, the solar absorption of In 2O3, WO3 and CdIn2O4 could be improved by carbon doping. The doped materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis, scanning electron microscopy, and solid-state nuclear magnetic resonance. The photoelectrochemical activity for water splitting was evaluated under near UV-visible light and visible light only irradiation conditions. Carbon doping improves the photocurrent densities of In2O3, WO3 and CdIn2O 4 electrodes. A high contribution (>40%) of the photocurrent density was observed to result from visible light. Different synthetic parameters, including dopant concentration, calcination temperature and film thickness, were optimized to achieve the best photoelectrochemical performance. The analyses presented in this thesis shows that In2O3, WO3 and CdIn2O4 are promising photocatalysts and can be suitably doped to improve the electrochemical properties for solar conversion applications.
Raftery, Purdue University.
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