Synthesis, physical and semiconducting properties of SnS2 prepared by chemical route
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The present study focused on the physical and electrochemical properties of stannic sulfide SnS2 synthesized by a template-free chemical route using thiourea as a precursor. SnS2 powder was characterized by X-ray diffraction (XRD), diffuse reflectance and Raman. The XRD pattern confirmed the formation of the hexagonal phaseSnS2 (SG: P-3m1) with the lattice parameters a = 3.639 Å, c = 5.868 Å and a mean crystallite size of ~ 60 nm. The optical measurements gave a direct transition of 2.26 eV, further transition indirectly allowed was observed at 1.63 eV. The Mott-Schottky plot recorded in Na2SO4 (0.1 M) electrolyte exhibits a linear behavior, characteristic of n-type conductivity and confirmed by chronoamperometry. The flat band potential (−0.63 VSCE) is close to the photocurrent onset potential (Eon= −0.64 VSCE) and a donor density of 3.54 × 1016 cm−3 was determined. The electrochemical impedance spectroscopy measured in the range (10−2 − 5 × 104 Hz) showed two semicircles assigned to a faradic charge transfer (Rct = 2.46 kΩ cm2) and grain boundaries contribution (Rgb= 13.69 kΩ cm2). The conduction band, located at −4.02 eV below vacuum, is made up of Sn4+: 5p while the valence band (−6.28 eV) derives mainly from S2−: 3p. As an application, Rhodamine B was successfully oxidized by photocatalysis on SnS2, 93.67% of the initial concentration (10 mg L−1) disappeared after 3 h of exposure to solar light (90 mW cm−2).
This work was supported by the Faculty of Chemistry (U.S.T.H.B., Algiers) with the collaboration of the institute of Molecules & Materials of Le Mans, CNRS, University of Maine, France. The authors would like to thank Pr. A. Azaze for the XRD patterns and Dr. S. Kaizra for his help.
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