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

In the previous study of ZnIn2S4 and SrTiO3 composite, there is only ZnIn2S4/SrTiO3 interface for the charge transfer. To obtain more kinds of charge transfer channels, a new hydrothermal method is used to promote ZnIn2S4 reacting with Cl-+OH- to produce In(OH)3, resulting into ZnIn2S4/SrTiO3/In(OH)3-x formation. Except for a type-Z migration path on the interface of ZnIn2S4/SrTiO3, a new type-II transfer path is obtained on interface of SrTiO3/In(OH)3 to further accelerate the charge separation. Moreover, the valence band holes of SrTiO3, the conduction band electrons of ZnIn2S4 and In(OH)3 are preserved to use in the photocatalytic reaction. After 30 min of ultraviolet light irradiation, the ZnIn2S4/SrTiO3/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 H2 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 ZnIn2S4/SrTiO3/In(OH)3-21 sample is used for the detoxification of wastewater and generation of renewable energy source. [Display omitted] •ZnIn2S4 reacts with Cl-+OH- to generate In(OH)3 in preparation of SrTiO3.•The optimal sample displays the activity of fast degradation, H2 evolution and CO2 reduction.•Accurate rate attains 95 % for efficiency prediction by neural network model calculation.•The excellent photocatalytic activity comes from a type-Z+II energy band configuration.•Final products are non-toxicity based on TEST calculation and bacterial growth test.