Atomic and Electronic Structure of the Edges of multilayer and Monolayer Tin disulfide (SnS₂)

Because of its two-dimensional structure and semiconducting properties, tin disulfide (SnS₂) is of interest for applications in electrochemical catalysis and sensing, as an electron transport layer for photovoltaics, and as an active material in photodetectors and thin film transistors. While the atomic and electronic structure of the basal planes of bulk and monolayer SnS₂ are well known, the same is not known for the edges, which could have a major influence on the performance of SnS₂ in the aforementioned applications. This paper reports on density functional theory (DFT) simulations and experimental measurements of the atomic and electronic structure of the edges of multilayer and monolayer SnS₂ under different chemical conditions. We found that the band gap of the SnS₂ edges becomes smaller with increasing sulfur coverage, and thereby determined the influence of chemical synthesis conditions on the electronic structure of the edges. We also found that as-synthesized SnS₂ has unpaired electrons at the edges, which suggests a direction to solve the degradation issue of SnS₂ as a catalyst in aqueous electrolytes.