Facile fabrication of 3D flower-like heterostructured g-C3N4/SnS2 composite with efficient photocatalytic activity under visible light

Abstract

3D flower-like heterostructured g-C₃N₄/SnS₂ composites were fabricated by a facile solvothermal method. The obtained g-C₃N₄/SnS₂ composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), N₂ sorption–desorption, and ultraviolet-visible diffuse reflection spectroscopy (DRS). The SEM results showed that the SnS₂ nanoflakes assembled into hierarchical flowers when g-C₃N₄ was introduced into the system. The elemental mapping images revealed that g-C₃N₄ and SnS₂ nanoflakes uniformly assembled together to form the hierarchical flowers. The HRTEM image showed clear heterojunction structure at the interfaces between g-C₃N₄ and SnS₂ nanoflakes. The DRS characterization showed that the light absorption exhibited regular red-shifts upon the increase of the g-C₃N₄/SnS₂ mass ratio. In the photocatalytic reduction of aqueous Cr(VI) under visible-light irradiation, g-C₃N₄/SnS₂ composites exhibited enhanced activities, which were much higher than that for pure SnS₂, SnS₂/TiO₂, and PM-g-C₃N₄/SnS₂ (a physical mixture of g-C₃N₄ and SnS₂). The photoelectrochemical measurement confirmed that the separation efficiency of electron–hole pairs was greatly improved for the formation of heterojunction structure. It was also shown that the formate or hydrogen ions added systematically accelerated the photo-reduction rates of Cr(VI). A possible photocatalytic mechanism for g-C₃N₄/SnS₂ composites was proposed.