Nano-structured black TiO2 photo-anodes for photo-electrochemical water-splitting

Photo-electrochemical catalytic water-splitting refers to the use of catalytic materials to split water into its constituents, hydrogen (H2) and oxygen (O2). Titanium dioxide is the most used material in this field, however the conversion efficiencies are still too low due to the low absorption in the visible range and the inevitable electron-hole recombination. In literature TiO2 nano-structures appear to be the most promising due to the supposed reduction of the recombination phenomenon and the high-opened configuration that increased the surface which faces the light. The main purpose of this thesis work was to study nano-ordered structures of TiO2 thermally treated in oxidizing, reducing and vacuum atmosphere, to be used as photo-anodes in a photo-electrochemical cell. The nano-hierarchical structures investigated are called tree-like nano-structures and are made using the Pulsed Laser Deposition (PLD) technique. In the following thesis work, we have changed different parameters during the synthesis of the photo-anodes in order to find the best combination of them in terms of resulting photo-activity. The various investigated parameters are: - initial materials used for the formation of titanium dioxide film on the photo-anodes through the pulsed laser deposition method; - the deposition atmosphere of the photo-anode in the pulsed laser deposition method; - the atmosphere and the thermal treatments.