Benzotrithiophene-based Covalent Organic Framework Photocatalysts with Controlled Conjugation of Building Blocks for Charge Stabilization

Covalent organic frameworks have recently shown high potential for photocatalytic hydrogen production. However, their structure-property-activity relationship has not been sufficiently explored to identify a research direction for structural design. Herein, we report the design and synthesis of four benzotrithiophene (BTT)-based covalent organic frameworks (COFs) with different conjugations of building units, and their photocatalytic activity for hydrogen production. All four BTT-COFs had slipped parallel stacking patterns with high crystallinity and specific surface areas. The change in the degree of conjugation was found to rationally tune the rate of photocatalytic hydrogen evolution. Based on the experimental and calculation results, the tunable photocatalytic performance could be mainly attributed to the electron affinity and charge trapping of the electron accepting units. This study provides important insights for designing covalent organic frameworks for efficient photocatalysts.

Automated summary

In this study, four benzotrithiophene-based covalent organic frameworks (COFs) with different conjugations were designed and synthesized, and it was found that the degree of conjugation can tune the rate of photocatalytic hydrogen production. The electron affinity and charge trapping of the electron accepting units were identified as the main factors affecting the photocatalytic performance. This research provides important insights for designing efficient photocatalysts using covalent organic frameworks.