A spatial homojunction of titanium vacancies decorated with oxygen vacancies in TiO 2 and its directed charge transfer.

The n-p homojunction design in semiconductors could enable directed charge transfer, which is promising but rarely reported. Herein, TiO 2 with a spatial n-p homojunction has been designed by decorating TiO 2 nanosheets with Ti vacancies around nanostructured TiO 2 with O vacancies. 2D 1 H TQ-SQ MAS NMR, EPR and XPS show the junction of titanium vacancies and oxygen vacancies at the interface. This spatial homojunction contributes to a significant enhancement in photoelectrochemical and photocatalytic performance, especially photocatalytic seawater splitting. Density functional theory calculations of the charge density reveal the directional n-p charge transfer path at the interface, which is proposed at the atomic-/nanoscale to clarify the generation of rational junctions. The spatial n-p homojunction provides a facile strategy for the design of high-performance semiconductors.