Synthesis, physical and semiconducting properties of SnS₂ prepared by chemical route

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 V_SCE) is close to the photocurrent onset potential (E_on= −0.64 V_SCE) 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 (R_ct = 2.46 kΩ cm²) and grain boundaries contribution (R_gb= 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).