Molecular Heterostructures of Covalent Triazine Frameworks for Enhanced Photocatalytic Hydrogen Production

• Published in: Angewandte Chemie International Edition Vol. 58; no. 26; pp. 8676 - 8680
• Main Authors: Huang, Wei, He, Qing, Hu, Yongpan, Li, Yanguang
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 24-06-2019
• Edition: International ed. in English
• Subjects: Charge efficiency; Covalence; covalent triazine frameworks; Current carriers; Electrochemical analysis; Electrochemistry; Electron recombination; Heterostructures; Hybrids; hydrogen evolution; Hydrogen production; Irradiation; Light irradiation; Photocatalysis; Polymerization; Polymers; Radiation; Recombination; Separation; sequential polymerization; Structure-function relationships; Triazine
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201900046

Conjugated polymers have emerged as promising candidates for photocatalytic H2 production owing to their structural designability and functional diversity. However, the fast recombination of photoexcited electrons and holes limits their H2 production rates. We have now designed molecular heterostructures of covalent triazine frameworks to facilitate charge‐carrier separation and promote photocatalytic H2 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 H2 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.
Happily separated: Molecular heterostructures of covalent triazine frameworks were constructed by sequential polymerization to facilitate charge‐carrier separation and photocatalytic H2 evolution (see picture; TEOA=triethanolamine). The selective incorporation of electron‐withdrawing benzothiadiazole and electron‐donating thiophene moieties led to a remarkable H2 evolution rate of 6.6 mmol g−1 h−1 under visible‐light irradiation for the optimal hybrid.