Anchoring Bi2S3 quantum dots on flower-like TiO2 nanostructures to boost photoredox coupling of H2 evolution and oxidative organic transformation.

ABSTRACT

The rational integration of semiconductor quantum dots (QDs) with anatase TiO2 nanostructures is a promising strategy to develop efficient photocatalysts. Herein, Bi2S3QD/TiO2 photocatalyst was constructed by controllably depositing Bi2S3 QDs on flower-like TiO2 nanostructures and used for the photocatalytic redox-coupling reaction of H2 evolution and oxidative transformation of benzyl alcohol. The abundant amino groups in TiO2 nanostructures served as the anchoring sites for uniform growth of Bi2S3 QDs. The anchoring of Bi2S3 QDs onto TiO2 nanostructures not only enhanced the photoabsorption ability and the photogenerated charge separation efficiency but also afforded powerful photogenerated charge carriers and abundant active sites for the photocatalytic reaction. As a result, the Bi2S3QD/TiO2 photocatalyst exhibited a favorable performance in the redox-coupling reaction, providing the high production rates of H2 up to 4.75 mmol·gcat-1·h-1 and benzaldehyde up to 6.12 mmol·gcat-1·h-1, respectively, as well as an excellent stability in the long-term photocatalytic reaction. Meanwhile, a trace amount of water in the reaction system could act as a promoter to accelerate the photocatalytic redox-coupling reaction. The photocatalytic mechanism following S-scheme heterojunction was proposed according to the systematic characterizations and experimental results. This work offers some insight into the rational construction of efficient and cost-effective photocatalysts for the conversion of solar to chemical energy.