Molecular Heterostructures of Covalent Triazine Frameworks for Enhanced Photocatalytic Hydrogen Production

Conjugated polymers have emerged as promising candidates for photocatalytic H 2 production owing to their structural designability and functional diversity. However, the fast recombination of photoexcited electrons and holes limits their H 2 production rates. We have now designed molecular heterostructures of covalent triazine frameworks to facilitate charge‐carrier separation and promote photocatalytic H 2 production. Benzothiadiazole and thiophene moieties were selectively incorporated into the covalent triazine frameworks as electron‐withdrawing and electron‐donating units, respectively, by a sequential polymerization strategy. The resulting hybrids exhibited much improved charge‐carrier‐separation efficiency as evidenced by photophysical and electrochemical characterization. An H 2 evolution rate of 6.6 mmol g −1 h −1 was measured for the optimal sample under visible‐light irradiation ( λ >420 nm), which is far superior to that of most reported conjugated‐polymer photocatalysts.