Unveiling the role of temperature on structural, compositional, morphological, thermal and optical properties of hydrothermally synthesized SnS2 nanostructures

Recently, the layered metal dichalcogenides (LMDs) such as tin disulfide (SnS₂) has engrossed significant attention because of their n-type semiconducting tunable properties. A hydrothermal method was employed for the synthesis of SnS₂ nanostructures by varying reaction temperatures i.e. 160, 170 and 180 °C. To determine the crystallographic, micro-structural, morphological, elemental compositions, thermal and optical properties of the prepared samples, various characterizations such as XRD, Raman spectroscopy, FTIR, FESEM, EDS XPS, TGA, PL and UV spectroscopy were employed. The structural analysis revealed the hexagonal phase formation of prepared SnS₂ nanostructures with space group symmetry of P6₃mc (layer group no.: 186) in all the prepared samples. The sample prepared at 160 °C also exhibit orthorhombic crystal phase of SnS along with SnS₂ crystal phase. The intensity of diffraction peaks increased with rise in growth temperature which infers the crystallinity improvement and crystallite size growth. Raman and FTIR spectroscopy also confirm the formation of SnS₂ phase in synthesized samples. FESEM analysis showed the development of hexagonal shaped nanostructures for all the prepared samples. Elemental analysis showed the improvement of stoichiometry of SnS₂ with increase in reaction temperature. XPS results inferred the existence of Sn and S with +4 and −2 energy states respectively, confirmed the formation of SnS₂. The optical property analysis shows the emission in visible region. Furthermore, the band gap values get decreased i.e. 2.42 eV–2.34 eV with increase in growth temperature. Also, the refractive index of the synthesized samples was determined by various empirical models. The improvement of linear optical susceptibility (χ⁽¹⁾), nonlinear refractive index (n₂) and nonlinear optical susceptibility (χ⁽³⁾) suggest the usefulness of synthesized nanostructures in optical and photonic applications. Engineering of different properties of SnS₂ nanostructures with reaction temperatures suggests the potential usage of these nanostructures for optoelectronic applications.