Fabrication of plate-on-plate Z-scheme SnS2/Bi2MoO6 heterojunction photocatalysts with enhanced photocatalytic activity

A class of direct plate-on-plate Z-scheme heterojunction SnS 2 /Bi 2 MoO 6 photocatalysts was synthesized via a two-step hydrothermal method. The materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectra, Fourier transform infrared photoluminescence emission spectra, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity was estimated via the degradation of crystal violet (CV) and ciprofloxacin (CIP). The experimental results indicated that the 5 wt% SnS 2 /Bi 2 MoO 6 composites exhibited significantly enhanced performance in contrast to pure Bi 2 MoO 6 or SnS 2 nanoflakes, and were also superior to the popular TiO 2 (P25). The degradation reaction accorded well with the first-order reaction kinetics equation; the rate constant of CV using a SnS 2 content of 5 wt% photocatalyst was ~ 3.6 times that of the Bi 2 MoO 6 and 2.4 times that of SnS 2 . Furthermore, a SnS 2 content of 5 wt% exhibited a 1.7 times higher photocatalytic activity of CIP than that of pure Bi 2 MoO 6 , and 1.3 times that of pure SnS 2 . Radical trapping experiments and an electron spin resonance technique indicated that h + and ·OH were the dominant active species involved in the degradation process. A plasmonic Z-scheme photocatalytic mechanism was proposed to explain the superior photocatalytic activities and efficient separation of photogenerated electrons and holes.