Introducing Ti3+ defects based on lattice distortion for enhanced visible light photoreactivity in TiO2 microspheres

Abstract

Defective titanium dioxide (TiO₂) is of much significance due to its improved visible light photoreactivity. Generally, the existence of defects leads to imperfections in the crystal lattice, which in turn affect the dynamics of the evolution of defects and the corresponding physical properties of TiO₂. Until now, how lattice distortion affects the formation of Ti³⁺ defects as well as the corresponding visible light photoreactivity in TiO₂ has remained elusive. Herein, we have successfully introduced Ti³⁺ defects based on lattice distortion in TiO₂ microspheres and found the photocurrent of anatase TiO₂ has been significantly enhanced from 1.78 to 80 μA cm⁻² with an increase in photocatalytic activity of almost three times under visible light irradiation. Furthermore, we show that lattice distortions have minimal contribution to enhancing the visible light photocatalytic activity because the band gap cannot be narrowed due to the absence of Ti³⁺ defects, yet the existence of lattice distortions could suppress the recombination of electron–hole pairs. Moreover, the formation of Ti³⁺ defects is energetically favored in lattice-distorted TiO₂ compared to that of pristine TiO₂. This work highlights the design and development of highly efficient TiO₂ photocatalysts that operate under visible light irradiation.