In Situ Grown Single-Atom Cobalt on Polymeric Carbon Nitride with Bidentate Ligand for Efficient Photocatalytic Degradation of Refractory Antibiotics

Semiconductor photocatalysis is a promising technology to tackle refractory antibiotics contamination in water. Herein, a facile in situ growth strategy is developed to implant single-atom cobalt in polymeric carbon nitride (pCN) via the bidentate ligand for efficient photocatalytic degradation of oxytetracycline (OTC). The atomic characterizations indicate that single-atom cobalt is successfully anchored on pCN by covalently forming the Co-O bond and Co-N bond, which will strengthen the interaction between single-atom cobalt and pCN. This single-atom cobalt can efficiently expand optical absorption, increase electron density, facilitate charge separation and transfer, and promote OTC degradation. As the optimal sample, Co(1.28%)-pCN presents an outstanding apparent rate constant for OTC degradation (0.038 min(-1)) under visible light irradiation, which is about 3.7 times than that of the pristine pCN. The electron spin resonance (ESR) tests and reactive species trapping experiments demonstrate that the(1)O(2), h(+), center dot O-2(-), and center dot OH are responsible for OTC degradation. This work develops a new way to construct single-atom-modified pCN and provides a green and highly efficient strategy for refractory antibiotics removal.