2.2. Experimental Details

The π-SnS nanoparticles were synthesized using a simple chemical precipitation (CP) process. In a standard procedure, a 0.5 M C₂H₅NS solution and SnCl₂·2H₂O solution at a selected concentration (0.04, 0.08, 0.12, 0.16, and 0.20 M corresponding to [Sn]/[S] ratio of 0.08, 0.16, 0.24, 0.32, and 0.40) were prepared using deionized water (DI) water and acetone, respectively. The prepared SnCl₂·2H₂O precursor solution along with 0.05 M EDTA chelating agent were poured into a 100 mL beaker and stirred vigorously for 10 min at 40 °C under an ambient atmosphere until a clear solution was obtained, which indicated the formation of complex tin ions through a reaction process. Next, the C₂H₅NS precursor solution was added into the reaction mixture, which resulted in a systematic color change of the solution from white to black during the next 40 min. Throughout the reaction, the stirring speed was maintained at 250 rpm, and the reaction solution was cooled to room temperature after completion of the process. The schematic representation of π-SnS nanoparticles synthesis and thin film preparation is shown in Figure 1. The precipitates collected from the solution were washed thoroughly using DI water before centrifugation to remove residual impurities. The product was then dried at 110 °C for 6 h in an oven. The powder was collected in a vial and placed in a desiccator for characterization.

Schematic representation of tin sulfide polymorph (π-SnS) nanoparticles synthesis and π-SnS thin film preparation.