Atomically dispersed iron on carbon nitride with enhanced oxygen adsorption for efficient and scalable photooxidation

Selective oxidation of C-H bonds represents a pivotal transformation for upgrading hydrocarbon feedstocks into value-added chemicals, yet achieving this under mild conditions remains a formidable challenge. We herein disclose a single-atom photocatalytic system featuring nonsymmetric Fe-N3Br sites anchored on melem that enables efficient photooxidation of C(sp3)-H bonds under mild conditions. The coordination environment facilitates Griffiths-type O2 adsorption and realizes a high toluene conversion rate of 9.27 × 104 μmol g−1 h−1. Experimental and theoretical studies indicate that the Fe-N3Br configuration reduces the Fe 3d splitting energy, enhances the O2 adsorption, and facilitates O2 activation, thereby promoting superoxide radical (•O2-) generation. The catalyst demonstrates broad functional group tolerance (43 examples, up to 97% yield), and good scalability, enabling a 1000 mmol-scale continuous-flow reaction. This work demonstrates the importance of the single-atom site coordination in governing oxygen activation and provides a scalable, green photocatalytic platform for C-H functionalization. This study reports a single-atom photocatalytic system featuring Fe-N3Br sites anchored on melem. The modified Fe 3d electron distribution and enhanced oxygen activation enable efficient, scalable toluene photooxidation under mild conditions.