Construction of Fe2O3/g-C3N5 heterojunction and photocatalytic degradation of antibiotics and mechanism analysis.

The widespread use of antibiotics has led to significant water pollution. Photocatalysis can effectively degrade antibiotics, but the performance is greatly limited by the photogenerated carrier recombination in the photocatalytic material g-C₃N₅. Constructing heterojunctions can enhance interfacial charge transfer, leading to more stable and efficient photocatalysis. This study synthesized a Fe₂O₃/g-C₃N₅ heterojunction using the solvothermal method. The Z-scheme charge transfer mechanism facilitated efficient separation of photogenerated carriers, preserving photoelectrons and holes with high redox activity. This process generated a substantial amount of highly reactive free radicals such as ·O₂^- and ·OH, enabling the efficient degradation of tetracycline (TC). Under the optimal conditions of initial concentration of TC was 200 mg/L, the quality ratio of Fe₂O₃ and g-C₃N₅ was 1:2, the catalyst dosage was 50 mg and pH = 7.0, the TC degradation rate reached 92.46% within 60 min of visible light irradiation. The photocatalytic activity's enhancement was attributed to broad spectral absorption and effective photogenerated carrier separation. Furthermore, the photocatalytic performance can be affected by the presence of inorganic salt ions such as HCO₃^- and CO₃^2-.