Minimalist preparation and photocatalysis properties of a spinyball-like indium-based composite suitable for different light conditions

The CdIn2S4/In2S3/CaIn2S4 composites were successfully prepared by an extremely simple programmed temperature hydrothermal method, which present a spinyball-like structure with a micro-sphere diameter of about 2.5–3 µm. X-ray diffraction analysis (XRD) results show that CaIn2S4 and CdIn2S4 exist in the form of cubic phase, and In2S3 exists in the form of cubic β-In2S3 in the composites. By discussing the relationship between the change of strain gravity and the change of cell parameters of CaIn2S4 after compounding In2S3 and CaIn2S4, the effects of crystal lattice change, crystal face growth and inhibition on the photocatalytic activity were studied. Meanwhile, through the photoluminescence spectra (PL), electrochemical impedance spectra (EIS), and transient photocurrent response analysis, the recombination of CaIn2S4, In2S3, and CdIn2S4 can accelerate the charge transfer and inhibit the recombination of electron–hole pairs in the CdIn2S4/In2S3/CaIn2S4 composites, so that higher photocatalytic performance can be obtained. Using methyl orange (MO) as the degradation object, the photo-degradation properties of the as-composites were studied and compared, and the results show that spinyball-like In2S3/CaIn2S4 and CdIn2S4/In2S3/CaIn2S4 exhibit high photocatalytic activity for degradation of MO under visible light and simulated sunlight, respectively. Furthermore, with Pt loaded as a co-catalyst, in Na2S aqueous solution, the hydrogen production rate of CdIn2S4/In2S3/CaIn2S4 photocatalysts is 74.9 μmol·g−1 (8 h), which is 8 times that of the commercially available TiO2. Furthermore, based on the results of the trapping experiment of CdIn2S4/In2S3/CaIn2S4, a possible photocatalytic mechanism was proposed, and the effect of multi-path photo-generated electron migration in the photocatalytic process was explained.