A spatial homojunction of titanium vacancies decorated with oxygen vacancies in TiO2 and its directed charge transfer

Abstract

The n–p homojunction design in semiconductors could enable directed charge transfer, which is promising but rarely reported. Herein, TiO₂ with a spatial n–p homojunction has been designed by decorating TiO₂ nanosheets with Ti vacancies around nanostructured TiO₂ with O vacancies. 2D ¹H 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.