Sulfur-Doped COF for Electrochemical H₂O₂ Production and Synergistic Tetracycline Degradation

Covalent organic frameworks (COFs) have shown promising potential in electrochemical applications due to their highly tunable chemical structures and large surface areas. However, the limited charge-transfer properties of conventional COFs restrict their electrocatalytic performance. In this work, sulfur species were introduced into the COF framework via sulfurization to enhance the electrochemical properties. The effects of sulfurization on the electrochemical performance of COFs were systematically evaluated in both cathodic and anodic systems, revealing significant improvements in cathodic H₂O₂ generation and anodic tetracycline degradation. Furthermore, sulfurization markedly optimized the interfacial properties of the electrodes, leading to enhanced charge accumulation at the electrode-electrolyte interface and facilitating electron transport within the framework, thereby improving overall electrocatalytic efficiency and activity. When applied in a practical two-electrode system, the sulfurized COF enabled synergistic tetracycline degradation and hydrogen peroxide production, achieving approximately 93% tetracycline removal in 4 h at 2.4 V while maintaining excellent electrode stability. These results demonstrate its potential for sustainable water treatment applications.