Characterization and Modification of UV-Vis Spectrum Solar Energy Water Splitting Material for Storable Fuel Generation

  • Jehad Abed

Student thesis: Master's Thesis

Abstract

The energy harvested from the sun is an everlasting source with minimal effect on the environment. However, due to the lack of reliability and consistency in supply, the harvested energy from the sun needs to be converted and stored into a more reliable and effective means of fuel that can be used on demand. One of the promising solarpowered technologies is the production of hydrogen fuel from an abundant source such as water. Compared to conventional forms of fuel, hydrogen can be easily stored and distributed. The overall goal is to achieve a system that produces hydrogen with minimum components and waste using water splitting technology. The produced hydrogen is suitable for use in fuel cells and thermal engines without further purification steps and massive chemical batteries for storage. In this thesis, we report on the effect of thermal annealing on the microstructure, optical properties and wettability of TiO2-based water-splitting (WS) composite using UV-Vis solar energy spectrum. The WS material used in this study is composed of a stack of three layers; SiO2, Al2O3 and TiO2, with a distribution of Localized Surface Plasmon Resonance structures (Au) formed on the TiO2 to obtain a multilayers composite material. The fabricated samples are annealed over a temperature range of 450˚C to 1100˚C under atmospheric conditions. The crystal structure and chemical composition are determined using; X-ray Diffractometer, Scanning Electron Microscope, Energy Dispersive Spectroscopy, High Resolution Scanning and Transmission Electron Microscope. UV-Vis spectroscopy is used to study the influence of thermal annealing on optical absorption spectrum. In addition, wettability alteration is assessed using both in-situ (Environmental Scanning Electron Microscope) and exsitu (sessile drop technique). Our findings reveal that thermal annealing leads to the transformation of amorphous TiO2 to its more stable phase anatase. This transformation significantly enhances the optical properties and increases the hydrophilicity of the material surface making it suitable for water-splitting activity. More importantly, the presence of plasmonic nanostructures allows the material to extend its photoactivity from UV region to visible light region. Furthermore, the gold nanocrystals are found to prefer the orientation during their evolving and growth after thermal annealing. This specific compact orientation was reported to increase the efficiency of water splitting activity.
Date of AwardMay 2017
Original languageAmerican English

Keywords

  • Harvested Energy
  • Hydrogen Fuel
  • Solar-Powered Technologies
  • Thermal Annealing
  • Titanium oxide (TiO2).

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