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

Abstract Covalent organic frameworks (COFs) containing dioxin‐linkages are highly valued for their exceptional chemical stability, which is essential for practical use. However, research on dioxin‐based COFs remains limited. Herein, a unique nonplanar 2D COF, designated as TCP‐COF, constructed from catechol‐porphyrin units interconnected by 1,4‐dioxin bonds, exhibiting a staggered AAA stacking pattern, is presented. Remarkably, TCP‐COF can undergo in situ exfoliation to produce ultrathin 2D nanosheets when it is utilized as a photocatalyst for hydrogen peroxide (H₂O₂) generation in water and air, without the need for additives. This exfoliation process is primarily driven by the distortion of porphyrin units and weak π–π interaction between adjacent layers in TCP‐COF. The resultant ultrathin nanosheets significantly reinforce catalytic activity, achieving a photocatalytic H₂O₂ production rate of 3077 µmol g⁻¹ h⁻¹. The mechanism underlying H₂O₂ photosynthesis is further explored through a combination of experimental analyses and theoretical calculations. This study provides valuable insights for the development of efficient COF‐based photocatalysts for H₂O₂ evolution.