Highly efficient heterostructured stannic disulfide/stannic anhydride hybrids: Synthesis, morphology, and photocatalytic reduction of chromium (VI) under visible light.

Highly efficient heterostructured stannic disulfide/stannic anhydride (SnS/SnO) hybrids with different morphologies were fabricated via a two-step hydrothermal method. The composition and morphology of the obtained products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (DRS). The SEM images showed that core-shell structured SnS/SnO nanotubes and hierarchical SnS flowers decorated with SnO particles were fabricated under different synthetic conditions. The DRS results of the hybrids showed that the absorption edges were gradually redshifted with increasing SnS content. In the photocatalytic reduction of chromium (VI) under visible light, the SnS/SnO hybrid prepared with thioacetamide addition of 0.60 g exhibited the best photocatalytic activity, which was approximately 6.8 times higher than that of pure SnS. This increase in the reduction performance might be ascribed to the strengthened absorption of visible light, the rapid interfacial charge transfer and the promoted charge separation efficiency. Photocurrent- response measurements, electrochemical impedance spectroscopy, and photoluminescence emission tests confirmed the faster charge transfer and efficient charge separation over the heterostructured SnS/SnO hybrids. Lastly, a photocatalytic reduction mechanism for chromium (VI) over SnS/SnO hybrids was proposed.