H2O2-modified biochar for BC-g-C3N4/COF heterojunction toward efficient tetracycline degradation

The growing severity of environmental pollution demands the development of efficient photocatalytic material systems for the degradation of aquatic pollutants, such as tetracycline (TC) antibiotics. In this work, BC-g-C 3 N 4 /COF was modified via 30% NaOH, 30% HNO 3 , and 30% H 2 O 2 treatments to regulate its structure and photocatalytic performance. The H 2 O 2 -modified sample exhibits the highest activity, achieving 72.72% TC degradation within 120 min and reaching 92.73% under optimized conditions (10% H 2 O 2 ), significantly outperforming other modification strategies. Mechanistic studies reveal that ·O 2 − is the dominant reactive species. The enhanced performance is attributed to a favorable band structure, improved charge separation, and reduced charge-transfer resistance. Photocatalytic efficiency is strongly influenced by environmental factors. Neutral pH (pH = 7), low TC concentration, and higher catalyst dosage promote degradation, while coexisting ions and humic acid inhibit the process via competitive adsorption and reactive species consumption. This study clarifies the synergistic photocatalytic mechanism of BC-g-C 3 N 4 /COF systems and provides theoretical support for their application in complex aqueous environments.