TiO₂ Phase Engineering by Millisecond Range Annealing for Highly Efficient Photocatalysis

Abstract

Air pollution and the energy crisis are the two main driving forces behind the development of alternative, environmentally friendly methods of energy production. Photoactive materials can be used both to clean the air and to produce green hydrogen for clean energy. Transition metal oxides are one of the most considered materials for high-performance photocatalysis. In this work, we investigate the effect of millisecond flash lamp annealing (FLA) of TiO2 on the degradation of methyl blue (MB) and methyl orange (MO). To reduce the energy consumption of the TiO2 deposition process, the layers were made using magnetron sputtering at room temperature followed by millisecond FLA. By controlling the flash energy input, we can tune the phase formation of TiO2 films from pure anatase to mixed anatase/rutile phases. Scanning electron microscopy, positron annihilation spectroscopy, photoluminescence, and X-ray diffraction studies show that the crystal size and film quality increase with increasing annealing temperature. Photocatalytic experiments demonstrate that FLA-treated TiO2 films are active in degrading both MB and MO. This makes them attractive not only for the production of green hydrogen but also for the purification of water from medical contaminants.