Reactivity of Trapped and Accumulated Electrons in Titanium Dioxide Photocatalysis

Electrons, photogenerated in conduction bands (CB) and trapped in electron trap defects (Ti-ds) in titanium dioxide (TiO2), play crucial roles in characteristic reductive reactions. This review summarizes the recent progress in the research on electron transfer in photo-excited TiO2. Particularly, the reactivity of electrons accumulated in CB and trapped at Ti-ds on TiO2 is highlighted in the reduction of molecular oxygen and molecular nitrogen, and the hydrogenation and dehalogenation of organic substrates. Finally, the prospects for developing highly active TiO2 photocatalysts are discussed.