In situgrowth of porous TiO2with controllable oxygen vacancies on an atomic scale for highly efficient photocatalytic water splitting

Oxygen vacancies play an important role in metal oxide semiconductors to improve the photocatalytic efficiency. Herein, we developed an effective methodviaatomic layer deposition to control the formation of oxygen vacancies in porous TiO(2)at a single atomic layer. X-ray photoelectron spectra and electron paramagnetic resonance spectra confirmed the different concentrations of oxygen vacancies which were formed by regulating the stoichiometric ratio of TiO2. Time-resolved fluorescence decay spectra and photocurrent measurement results indicated that the oxygen vacancies accelerated the separation of charge carriers and prolonged the lifetime of electrons. As a result, the porous TiO(2)with abundant oxygen vacancies exhibited a much higher photocatalytic H(2)generation rate (3.41 mmol g(-1)h(-1)), about 20 times that with fewer oxygen vacancies. Combined with density functional theory calculation, the introduced oxygen vacancies could introduce a defect level and delocalize charges around them, thus extending the light absorption region and promoting separation and transfer of photogenerated electrons and holes. This defect engineering not only opens up a way to manipulate the stoichiometric ratio at an atomic level, but also provides a flexible template to support single atom catalysts for energy conversion.