Rational Fabrication of a Robust, Exfoliatable Catechol-Porphyrin Covalent Network for Enhanced H₂O₂ Photosynthesis

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) offer high chemical stability due to dioxin-linkages.
• Research on dioxin-based COFs is limited, hindering their practical applications.
• Developing stable and efficient COFs is crucial for advanced catalytic processes.

Purpose of the Study:

• To synthesize and characterize a novel nonplanar 2D COF with dioxin-linkages, named TCP-COF.
• To investigate the in situ exfoliation behavior of TCP-COF during photocatalysis.
• To evaluate the efficiency of TCP-COF-derived nanosheets for hydrogen peroxide generation.

Main Methods:

• Synthesis of TCP-COF from catechol-porphyrin units and 1,4-dioxin bonds.
• In situ exfoliation of TCP-COF into 2D nanosheets during photocatalysis.
• Photocatalytic hydrogen peroxide (H2O2) generation experiments in aqueous solution.
• Characterization of TCP-COF and its exfoliated nanosheets using advanced analytical techniques.
• Theoretical calculations to elucidate the reaction mechanism.

Main Results:

• A novel nonplanar 2D COF (TCP-COF) with a staggered AAA stacking pattern was successfully synthesized.
• TCP-COF undergoes spontaneous in situ exfoliation into ultrathin 2D nanosheets during H2O2 photocatalysis.
• The exfoliated TCP-COF nanosheets achieved a high photocatalytic H2O2 production rate of 3077 µmol g⁻¹ h⁻¹.
• The exfoliation process is attributed to porphyrin unit distortion and π-π interactions.

Conclusions:

• TCP-COF demonstrates exceptional stability and unique in situ exfoliation properties.
• Ultrathin COF nanosheets significantly enhance photocatalytic activity for H2O2 evolution.
• This work provides a new avenue for designing efficient COF-based photocatalysts.