Storage and re-release of photoelectrons to enhance the photocatalytic activity of TiO2

As for the structural design of photocatalytic materials, it is possible to prolong the recombination time by constructing heterojunctions to drive photogenerated carriers due to the preference between energy levels. However, the separation of transported electrons and holes appears only for the underlying physical properties and photocatalytic activity of the catalyst. The synergistic design of heterojunctions, including surface defect engineering as well as electron storage and delayed release in catalysts, has been rarely reported. In this work, a photocatalyst that loading TiO 2 on multilayer CoOOH was reported, achieving the modulation of the oxygen vacancies existing on the TiO 2 surface based on the heterojunctions. Compared with TiO 2 loading on Co 3 O 4 , more oxygen vacancies are available, and the stored photogenerated electrons are released one after another through the multilayer structure. In the photocatalytic oxidation of rhodamine-B (Rh-B), the activity is enhanced to four times comparing with that of TiO 2 . As a novel and unique structural design, the extraordinary performance deserves to be approved, and it is promising to be further investigated in the future. • CoOOH completes the modulation of oxygen vacancies on the TiO 2 surface. • TiO 2 photoelectrons are migrated for multiple times through CoOOH. • CoOOH possesses the ability to store photogenerated electrons. • TiO 2 -CoOOH realizes the gradual release of photoelectrons to prolong the recombination time of carriers.