Tailoring the Interfacial Microenvironment of Atomically Dispersed Zinc to Boost Electron Transfer Process for Water Purification

Introducing environmentally benign Zn single-atom catalysts (SACs) in Fenton-like reactions to induce electron transfer processes (ETP) holds great potential in advanced water remediation technologies. However, precise coordination of Zn SACs is highly required to selectively trigger the ETP pathway. Herein, under the guidance of density functional theory (DFT) predictions, we constructed asymmetric Zn-N₃Cl sites on N-doped carbon (NC) to unlock the electron-transfer reactivity of redox-inert Zn while maintaining structural robustness. Compared with the symmetric Zn-N₄ system, the Zn-N₃Cl system achieved a higher sulfamethoxazole (SMX) removal rate and PMS utilization efficiency by 4.4 and 2.3 times, respectively. Mechanism studies revealed that Cl doping significantly altered the electronic structure of Zn sites, thereby promoting their electron transfer capacity. The strongly polarized Zn-N₃Cl sites exhibited a notably enhanced interaction with PMS, facilitating the formation of Zn-N₃Cl/PMS* with high redox potential and lowering the energy barrier of the rate-determining step (RDS) for ETP. The Zn-N₃Cl system demonstrated outstanding catalytic reactivity toward various environmental interferences over a wide pH range. Notably, this system remained effective for the continuous flow-through treatment of pharmaceutical wastewater, coupling high catalytic reactivity and structural robustness. Our rational design of environmentally benign materials offers a blueprint for sustainable water remediation.