Fabrication of MOF-derived tubular In 2 O 3 @SnIn 4 S 8 hybrid: Heterojunction formation and promoted photocatalytic reduction of Cr(VI) under visible light.

Tubular In ₂ O ₃ @SnIn ₄ S ₈ hierarchical hybrid photocatalyst was firstly fabricated by a two-step method. The morphology and composition were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The XRD results show that the obtained In ₂ O ₃ microtubes were highly crystallized, while the SnIn ₄ S ₈ flakes prepared at low temperature were poorly crystallized. The SEM image of the hybrid shows that numerous SnIn ₄ S ₈ nanoflakes were assembled over the surface of In ₂ O ₃ microtubes. In ₂ O ₃ served as dispersing-templates have reduced the agglomeration of SnIn ₄ S ₈ flakes. Meanwhile, the heterojunctions formed at the interfaces between In ₂ O ₃ and SnIn ₄ S ₈ could facilitate the interfacial charge transfer, as well as promote the photocatalytic activity of the hybrid. In the treatment of Cr(VI)-containing wastewater, the In ₂ O ₃ @SnIn ₄ S ₈ hybrid not only exhibited strong adsorption ability, but also showed remarkably enhanced photocatalytic activity compared with pure SnIn ₄ S ₈ . The photocatalytic reaction constant k for In ₂ O ₃ @SnIn ₄ S ₈ was approximately 2.54 times higher than that of SnIn ₄ S ₈ . The efficient activity of this hybrid photocatalyst should be ascribed to the promoted separation efficiency of electron/hole pairs, which was proved by the following three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs), photocurrent responds, and EIS characterizations.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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