Benzotrithiophene-based covalent organic frameworks as efficient catalysts for artificial photosynthesis of H2O2 in pure water.

An emerging organic structure with excellent 2e- oxygen-reduction activity in the photosynthesis of H 2 O 2 has been developed, of which the photocatalytic performance was significantly improved after anchoring the active moiety into extending conjugated covalent organic frameworks. The resulting materials rendered high H 2 O 2 productivity in pure water. [Display omitted] • An emerging organic photocatalytic structure for the photosynthesis of H 2 O 2 from oxygen and water has been developed. • Extending conjugated COFs promotes H 2 O 2 productivity in pure water. • The suitable distance of active moiety generates the highest efficiency. • An alternative strategy for constructing 2e- oxygen reduction photocatalyst. Direct synthesis of hydrogen peroxide (H 2 O 2) using oxygen and water through the photocatalytic route is a prospective approach for the on-site production of H 2 O 2. However, the limited varieties of photocatalytic sites and ambiguous structure-active relationship impede the development of environmentally friendly technology. Herein, we report a active compound (benzotrithiophene, BTT) for the photosynthesis of H 2 O 2 using oxygen and water, and design four benzotrithiophene-based 2D covalent organic frameworks (BTT-COFs) linked with aromatic amines linkers. Significant enhancement in photocatalytic activity has been observed via the introduction of BTT struct into 2D COFs. The high crystallinity of COFs increases the visible light absorption ability and photostability of BTT. The suitable distance of BTT struct in COFs and the construction of donor–acceptor (D-A) structure further promote the carrier generation and transfer. The COF-BTT-TAPT exhibited the highest H 2 O 2 production rate of 620 μmol g−1 h−1. Mechanism investigation experiments have given the validation that BTT-COFs efficiently reduce oxygen in pure water to form H 2 O 2 under visible-light irradiation. This work paves a revolutionary way for designing and fabricating high-performance metal-free photocatalysts for visible-light-driven H 2 O 2 production. [ABSTRACT FROM AUTHOR]