Controlling the morphology while retaining the unique SnS stoichiometry of bulk tin sulfide produced by the rapid method of heating Sn foil in sulfur vapor by vapor phase reaction using two-furnace chemical vapor deposition system

The SnS allotrope of tin sulfide can be beneficial for various multifunctional device applications, but its synthesis is a rather challenging task, sometimes requiring the use of toxic materials. In this work, we propose a simple and rapid method to synthesize bulk SnS. We synthesized our material by heating Sn foil with S gas originating from the sublimation of S powder. Our rapid and controllable reaction conditions allow us to obtain solely a single phase of SnS while halting the formation of additional phases. We synthesized our material by placing Sn foil and S powder at different temperatures in a two-furnace chemical vapor deposition system. The S powder was heated to reach sublimation and its vapor was carried by an inert gas flow to the Sn foil, where the reaction occurred between vapor S and liquid Sn (which was heated in the second furnace). We performed a series of experiments with a wide range of reaction durations and varying temperatures of the Sn foil. We observed the different morphologies and found smoothing of the surface with increasing reaction duration and temperature, consistent with the expected increase in material grain size. We also inspected the sulfur uptake on the surface of the forming material with increasing reaction time and temperature. We conclude that the formation of solid SnS on top of the liquid Sn gradually decelerates the S uptake due to the lower solubility of S gas in the solid material, resulting in plateauing of the S uptake. With higher temperatures, the rapid formation of the solid SnS results in lower S content. We show that our material has a basal level of oxygen evolution reaction activity. Finally, we dropcasted a few (3–4) layers of SnS on a substrate after sonication and liquid exfoliation.