Donor-acceptor engineered ultrathin carbon nitride nanosheets with spatially separated redox sites for enhancing photocatalytic O2 activation and antibiotics degradation

Photocatalytic 1 O 2 generation has emerged as a promising technology for environmental remediation and organics synthesis. Nevertheless, the efficiency of photocatalytic 1 O 2 generation via O 2 activation through charge-transfer mechanism remains challenging in carbon nitride due to the weak dielectric screening effect. Herein, series of uric acid (UA)-modified ultrathin carbon nitride nanosheets (UCN-x) were fabricated by the simple supramolecular self-assembly process. Comprehensive characterizations revealed that the incorporation of UA pigment would induce purine structure into heptazine skeleton. Photocatalytic experiments showed that the modification of UA greatly enhanced photocatalytic 1 O 2 generation ability. The optimal UCN-2 exhibited superior photocatalytic degradation of tetracycline (TC) with the normalized TC degradation rate up to 10.03 mg TC g cat −1  min −1 , which was 2.1–31.1 times as high as that of reported photocatalysts. What's more, UCN-2 exhibited excellent photocatalytic TC degradation across diverse aqueous conditions, demonstrating significant potential in environmental remediation. Time-dependent density functional theory (TD-DFT) calculation revealed that the doping of UA could trigger the spatial separation of h + /e − distribution, with h + concentrated in UA pigment and e − concentrated in adjacent heptazine ring. The engineered adjacent redox sites were precisely tailored to align with the charge-transfer mechanism for photocatalytic 1 O 2 generation. This work established a fundamental framework for designing highly efficient photocatalysts with manipulated O 2 activation.