Preparation of Blue TiO2 for Visible-Light-Driven Photocatalysis

Abstract

Titanium dioxide (TiO2), which is regarded as a semiconductor photocatalyst, has drawn attention in the applications of photocatalysis, including hydrogen evolution reaction, carbon dioxide reduction, pollutant degradation, and biocatalytic or dye-sensitized solar cells due to its low toxicity, superior photocatalytic activity, and good chemical stability. However, there are still some disadvantages such as too large energy bandgap (~3.34 eV and ~3.01 eV for anatase and rutile phases, respectively) in the absorbance of all ranges of lights, which limits the photoelectrochemical performance of TiO2. Herein, we like to introduce photocatalytic blue TiO2 that is obtained by the reduction of TiO2. The blue TiO2 consists of Ti3+ state with high oxygen defect density that can absorb the visible and infrared as well as ultraviolet light due to its low energy bandgap, leading to enhance a photocatalytic activity. This chapter covers the structure and properties of blue TiO2, its possible applications in visible-light-driven photocatalysis, and mainly various synthetic methods even including phase-selective room-temperature solution process under atmospheric pressure.