Impact of Oxygen Vacancies on TiO2 Charge Carrier Transfer for Photoelectrochemical Water Splitting

Oxygen vacancies are recognized as the most prevalent defect in oxide materials. The effect of oxygen vacancies on the physicochemical properties of metal oxide semiconductors has attracted considerable attention in photocatalysis field. But so far, the impact of oxygen vacancies on charge carrier transfer for photoelectrochemical water splitting was unclear. In this work, TiO2 photoanodes with various oxygen vacancy concentrations was studied as a metal oxide model to clarify the impact of oxygen vacancies on charge carriers transfer behaviors. The potential distribution and electrochemical impedance spectroscopy results indicate that oxygen vacancies facilitate the charge carries diffusion in the TiO2, but are disadvantage of the charge carries drift in the TiO2/electrolyte interface. TiO2-400 photoanode with intermediate oxygen vacancy concentration exhibits the highest photocurrent density. It is expected that this work provides references to design and fabricate oxide semiconductors photoanodes for higher charge carrier utilization in the fields of solar-to-chemical energy conversion.