Conjugated microporous poly(benzothiadiazole)/TiO2 heterojunction for visible-light-driven H2 production and pollutant removal

- BBT is an organic semiconductor for photocatalytic H2 production and CIP degradation.
- BBT/TiO2 heterojunction improves H2 evolution and CIP degradation activity.
- The heterojunction interface enhances the photogenerated e−/h+ separation efficiency.
- The catalyst can work under broad visible light region up to ∼700 nm.

A π-conjugated microporous poly(benzothiadiazole) (hereafter denoted as BBT) is synthesized through palladium-catalyzed Sonogashira-Hagihara cross-coupling polycondensation, and used as a novel organic semiconductor photocatalyst for both photocatalytic H2 production and pollutant degradation under visible light (λ > 420 nm) irradiation. Furthermore, BBT/TiO2 heterojunction is conveniently fabricated through an in-situ polycondensation procedure of 4,7-dibromobenzo[c][1,2,5]thiadiazole and 1,3,5-triethynylbenzene in the presence of commercial TiO2. After optimizing the composition ratio, the resultant BBT/TiO2 heterojunction exhibited dramatically enhanced visible-light-responsive photocatalytic activities (∼18.0 and 20.4 times higher activity for H2 evolution and ciprofloxacin degradation, respectively) as compared BBT alone. Detailed investigations revealed that the BBT/TiO2 heterojunction interface can accelerate the photogenerated electron transferring from BBT to TiO2, and then improve the photoactivity. The present work exhibits some interesting points and dramatic improvement of photoactivity when an organic semiconductor is combined with an inorganic one, which provides a novel direction to exploit and fabricate photocatalyst for solar energy conversion and pollutant degradation.

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