GO nanosheets decorated with SnS nanoparticles: excellent photocatalytic performance under visible-light irradiation

In this study, pristine SnS and SnS/reduced graphene oxide nanostructures were synthesized using a simple and cheap co-precipitation method. To investigate the effect of graphene oxide concentration on the structural and optical properties and photocatalytic activity, SnS/graphene oxide nanocomposites were prepared with different concentrations of graphene oxide (5, 15, and 25 wt%). The synthesized nanostructures were analyzed using X-ray diffraction, FESEM, Raman spectroscopy, UV-Vis spectroscopy, photoluminescence techniques, and electrochemical impedance spectroscopy. The results of the XRD analysis confirmed the orthorhombic phase of tin sulfide for all nanostructures. The absence of a peak at 2θ = 10.21° for SnS/graphene oxide nanocomposites indicated that during the synthesis process, graphene oxide turns into reduced graphene oxide. The FESEM analysis results showed that surface cracking occurs for SnS/graphene oxide nanocomposites compared to pure graphene oxide sheets. This cracking of reduced graphene oxide sheets can act as sites for the growth of SnS nuclei on rGO. However, the presence of such nucleus sites for the growth of nanoparticles is an important factor in improving the photocatalytic efficiency of nanocomposites. The results of the Raman analysis of the nanocomposites show the highest reduction of oxygen for the SnS/rGO nanocomposite with 15 wt% concentration of graphene oxide, and this improves the conductivity and increases the separation of charge carriers. These results are confirmed by electrochemical impedance analysis with the longest lifetime (430 ns) and photoluminescence analysis with the least recombination of charge carriers for this nanocomposite. Therefore, the results of the research on the photocatalytic activity of the synthesized nanostructures for the decomposition of methylene blue under visible light irradiation show that the SnS/rGO nanocomposite has a higher efficiency than pristine SnS, and the optimal concentration of graphene oxide in the nanocomposites synthesized for 150 minutes to obtain the highest photocatalytic efficiency (more than 90%) was 15 wt%.