Preparation of CuFe₂O₄/In₂S₃ composite for photocatalytic degradation of tetracycline under visible light irradiation

The CuFe2O4/In2S3 composite was prepared by a simple mechanical grinding process and used for the photocatalytic degradation of tetracycline (TC) under visible light irradiation. The results showed that the photocatalytic degradation activity for tetracycline on the CuFe2O4/In2S3 composite photocatalyst with a mass ratio of 1:3 was 95.2%, which was higher than that of 12 and 63% on pure CuFe2O4 and In2S3 alone, as well as 89% on CuFe2O4/In2S3(1:1) and 79% on CuFe2O4/In2S3(3:1). Tetracycline photodegradation on CuFe2O4/In2S3 was a first-order reaction, and the rate constant of the tetracycline degradation reaction under visible light irradiation was 0.02162 min(-1), which was 38 and 3.1 times higher than that of CuFe2O4 and In2S3 alone, respectively. This characterization results showed that CuFe2O4/In2S3(1:3) composites showed the high photodegradation efficiency and the highest photogenerated carrier separation efficiency. In addition, on the optimal reaction condition, an optimal photodegradation of 95.2% for tetracycline would achieved. The stable construction of the CuFe2O4/In2S3 heterojunction and the narrow band gap of CuFe2O4 or In2S3 enhance the light absorption capacity of the catalyst. The mechanism study shows that CuFe2O4 and In2S3 are excited by visible light to produce electrons, which transfer to the conduction band of CuFe2O4 and In2S3. Subsequently, the separation and transfer of photogenerated holes and photogenerated electrons are effectively improved by the Z-scheme photogenerated carrier transfer mechanism. The photogenerated electrons can reduce O-2 to produce O-2(-), which together with h(+) on the valence band becomes the main oxidation active species in the reaction system, and efficient oxidative degradation of tetracycline can be achieved.