Highly crystalline and water-wettable benzobisthiazole-based covalent organic frameworks for enhanced photocatalytic hydrogen production

Semiconducting benzobisthiazole-based covalent organic frameworks were prepared and reported. Its high crystallinity, great water-wettability and fast charge separation dynamics cooperatively endow the material with an extraordinary H2 evolution rate of 48.7 mmol g1 h1 under visible light irradiation. Two-dimensional covalent organic frameworks are promising for photocatalysis by virtue of their structural and functional diversity, but generally suffer from low activities relative to their inorganic competitors. To fulfill their full potential requires a rational tailoring of their structures at different scales as well as their surface properties. Herein, we demonstrate benzobisthiazole-based covalent organic frameworks as a superior photocatalyst for hydrogen production. The product features high crystallinity with ordered 2.5-nm-wide cylindrical mesopores and great water wettability. These structural advantages afford our polymeric photocatalyst with fast charge carrier dynamics as evidenced by a range of spectroscopic characterizations and excellent catalytic performances when suspended in solution or supported on melamine foams. Under visible-light irradiation, it enables efficient and stable hydrogen evolution with a production rate of 487 mu mol h(-1) (or a mass-specific rate of 48.7 mmol g(-1) h(-1))-far superior to the previous state of the art. We also demonstrate that hydrogen production can be stoichiometrically coupled with the oxidation conversion of biomass as exemplified by the conversion of furfuryl alcohol to 2-furaldehyde.

Automated summary

Semiconducting benzobisthiazole-based covalent organic frameworks with high crystallinity, great water-wettability, and fast charge separation dynamics were developed as a superior photocatalyst for hydrogen production. The material exhibited an extraordinary H2 evolution rate of 48.7 mmol g1 h1 under visible light irradiation. The polymeric photocatalyst featured ordered cylindrical mesopores and excellent catalytic performances, outperforming previous state-of-the-art photocatalysts.