Preparation of Fe-doped In₂S₃/In₂O₃ Composite for Photocatalytic Degradation of Tetracycline

Tetracycline (TC) is not only a threat to aquatic ecosystems and the health of organisms but also a crucial contributor to the drug resistance of bacteria. The photodegradation of TC is an effective strategy for overcoming antibiotic pollution in the water environment. Fe–In2O3/In2S3 composites were successfully synthesized via a hydrothermal method for the photocatalytic degradation of TC under visible light illumination. When the Fe doping content was 2%, the degradation rate of TC by the 2% Fe–In2O3/In2S3 composite under visible light irradiation reached 92.4%, which was higher than that of 41.5% for In2O3/In2S3, 86.7% for 1% Fe–In2O3/In2S3 and 79% for 3% Fe–In2O3/In2S3. The photodegradation of tetracycline on Fe–In2O3/In2S3 was a first-order reaction under visible light. The rate constant of photocatalytic tetracycline degradation was 5.12 × 10–3 min–1, which was 4.1 times greater than the rate constant of In2O3/In2S3. The characterization results revealed the excellent separation efficiency of the 2% Fe–In2O3/In2S3 composites for photogenerated electron–hole pairs, which increased the photodegradation efficiency. Furthermore, under the most suitable reaction conditions, the photodegradation rate of tetracycline was 92.4%. A mechanistic study revealed that the doping of Fe ions effectively improved the transfer efficiency of photoproduced charges and inhibited the combination of photoproduced electron–hole pairs, thereby improving the photocatalytic performance of the material and achieving efficient oxidative degradation of tetracycline.