Introduction of Ti3+ ions into heterostructured TiO2 nanotree arrays for enhanced photoelectrochemical performance.

The mixed-phase heterostructured TiO 2 nanotree arrays were synthesized by a secondary hydrothermal route, and Ti3+ ions were introduced into the arrays for enhanced photoelectrochemical performance. The results show that the arrays consist of heterostructures with anatase and rutile phases. XPS results indicate that during the hydrogenation process, part of Ti4+ ions transform to Ti3+ ions. Although the band gap shifts by only 0.1 eV, introduced defects and Ti3+ ions can greatly increase the efficiency of electron-hole separation. Photocurrent of the heterostructured TiO 2 nanotree arrays with introduced Ti3+ ions increases by 41 times, and the photocurrent density enhances from 0.0055 to 0.2272 mA/cm2. • Ti3+ ions were introduced into the arrays for enhanced photoelectrochemical performance. • It is a clean and convenient way to construct the inner structure of TiO 2. • Heterostructured TiO 2 nanotree arrays with large specific surface area were fabricated successfully. [ABSTRACT FROM AUTHOR]