Photoenzyme Coupling System: Covalent Organic Frameworks In Situ Production of Hydrogen Peroxide Cascaded with Unspecific Peroxygenase to Achieve C–H Bonds Selective Activation

As an efficient, sustainable, and environmentally friendly semiconductor material, covalent organic frameworks (COFs) can generate hydrogen peroxide (H₂O₂) by photocatalysis, attracting wide attention in recent years. Herein, the effects of hydroxyl, methoxyl, and vinyl groups of imide-linked two-dimensional (2D) COFs on the photocatalytic production of H₂O₂ were studied theoretically and experimentally. The introduction of vinyl groups greatly promotes the photogenerated charge separation and migration of COFs, providing more oxygen adsorption sites, stronger proton affinity, and lower intermediate binding energy, which effectively facilitates the rapid conversion of oxygen to H₂O₂. Further, we have integrated the properties of the photocatalytic in situ generation of H₂O₂ by COFs and the continuous consumption of H₂O₂ by unspecific peroxygenases (UPOs) to construct a mild and simple photoenzyme coupling system that can achieve selective activation of C-H bonds without the need of any external oxidants or sacrificial agents. This simple, stable, and compatible photoenzyme system avoids irreversible enzyme damage caused by excessive exogenous H₂O₂ and the utilization of sacrificial agents, thus providing an efficient and green pathway for fine chemical synthesis. This system not only breaks the restriction of continuous exogenous H₂O₂ supplementation on the UPO catalytic system but also provides a new practical application direction for semiconductor photocatalytic H₂O₂ production.