Oxygen-vacancies-engaged efficient carrier utilization for the photocatalytic coupling reaction.

An oxygen-vacancies-engaged photocatalytic mechanism was proposed to address the poor photo absorption and sluggish electron-hole separation of TiO 2. Electrons and holes are fully utilized for nitrobenzene reduction coupled with benzyl alcohol oxidation under visible light irradiation. • Oxygen vacancies (OVs) were generated through surface complexation under mild condition. • Fully making use of the photogenerated charge carriers rapidly promoted its separation and transfer efficiency. • Disclosing photoinduced electron transfer among photocatalysis. • The prepared TiO 2 exhibited good recyclability. Defects can greatly optimize the solar light harvesting capability and electronic structure of oxide materials. However, it remains challenging to achieve a defect engineering strategy under mild conditions. Meanwhile, the simultaneous exploitation of photogenerated holes (h+) and electrons (e−) to promote both photooxidation and photoreduction in a coupled system has rarely been reported. For the first time, we reveal an oxygen-vacancies-mediated photocatalytic strategy in which the electrons and holes are fully utilized for nitrobenzene reduction coupled with benzyl alcohol oxidation. The oxygen vacancies (OVs) generated in situ on the surface of TiO 2 greatly extend light absorption into the visible region and promote the photogenerated electron transport for efficient photocatalysis. The experimental and theoretical results together indicate that chemisorption on the TiO 2 surface decreases the oxidation potential of benzyl alcohol and causes an upward shift in its HOMO, which facilitates the oxidation reaction of benzyl alcohol to benzaldehyde. The in situ generated surface OVs also act as a bridge to enable the trapping and transferring of the photoinduced electrons to the nitrobenzene. This work provides a new perspective of utilizing the chemisorption between the reactant and catalyst to achieve a defect engineering strategy for synergetic photocatalysis. [ABSTRACT FROM AUTHOR]