Construction of ZnIn2S4/SrTiO3/In(OH)3 heterojunction for antibiotic removal, H2 evolution and CO2 reduction

In the previous study of ZnIn ₂S ₄ and SrTiO ₃ composite, there is only ZnIn ₂S ₄/SrTiO ₃ interface for the charge transfer. To obtain more kinds of charge transfer channels, a new hydrothermal method is used to promote ZnIn ₂S ₄ reacting with Cl ^-+OH ^- to produce In(OH) ₃, resulting into ZnIn ₂S ₄/SrTiO ₃/In(OH) ₃-x formation. Except for a type-Z migration path on the interface of ZnIn ₂S ₄/SrTiO ₃, a new type-II transfer path is obtained on interface of SrTiO ₃/In(OH) ₃ to further accelerate the charge separation. Moreover, the valence band holes of SrTiO ₃, the conduction band electrons of ZnIn ₂S ₄ and In(OH) ₃ are preserved to use in the photocatalytic reaction. After 30 min of ultraviolet light irradiation, the ZnIn ₂S ₄/SrTiO ₃/In(OH) ₃-21 sample degrade 87 % of lomefloxacin and 89 % of ofloxacin. The photodegradation rates of the lomefloxacin and ofloxacin reach 0.06 min ⁻¹ and 0.05 min ⁻¹, respectively. In addition, the photo-removal efficacies of the total organic carbon also attain 73 % and 62 % for these antibiotics degradation. Using the Back Propagation neural network model, The accurate rate achieves 95 % for the training of the photocatalytic efficiency. The rates of H ₂ and CO production are 2.749 mmol/g/h and 39.37 μmol/g/h. The concentrations of Escherichia coli are 0.79×10 ⁻⁶ CFU/mL and 0.83×10 ⁻⁶ CFU/mL in the solutions after photodegradation to indicate non-toxicity of the final products. The ZnIn ₂S ₄/SrTiO ₃/In(OH) ₃-21 sample is used for the detoxification of wastewater and generation of renewable energy source.