Heavily Nitrogen-Doped Dual-Phase Titanium Oxide Thin Films by Reactive Sputtering and Rapid Thermal Annealing

A novel nonequilibrium approach combining low-temperature reactive sputtering and rapid thermal annealing was developed to resolve the opposing requirements on crystallization and high dopant concentration for creating nitrogen-doped TiO2 (TiON) thin film with a mixture of anatase and rutile phases. The dual-phase TiON has a higher visible-light absorption and a smaller band gap than pure anatase TiON. Its superior photocatalytic performance was demonstrated by the highly hydrophilic conversion and faster photodegradation of organic pollutants under visible-tight illumination. Our work demonstrates that the crystal structure is a major factor in determining the visible-light photocatalytic activity of TiON.