Atomic Scale Imaging of Defects in Solution Grown Tin Disulfide

Tin disulfide (SnS₂), a layered material, has gained substantial attention in recent years due to its applications in various fields, including broadband photodetection spanning from UV to NIR regions, selective room-temperature gas-sensing of NO₂, serving as an anode material in sodium-ion batteries, and application in supercapacitors.¹ These applications arise are a result of a synergistic interplay between SnS₂’s inherent properties and the precise engineering of defects, such as vacancies, dislocations, and grain boundaries.² Along with these, other defects such as ripplocations are also present exclusively in layered materials.³ The control of such new defects and their influence on the properties and applications of layered materials is currently a wide subject of study.<br/>In this study, we utilized the solution chemistry method to synthesize nanocrystals of SnS₂. The phase purity of these nanocrystals was confirmed through powder X-ray diffraction, and their uniform nanosheet morphology was evident from SEM images. We have conducted a comprehensive analysis of defects using advanced microscopic techniques, specifically using aberration-corrected scanning transmission electron microscope. By directly imaging the layers of SnS₂ along [100] zone axis, we identified the presence of various defects at the core of nanocrystal, including line and screw dislocations, voids and warping of layers. While dislocations and voids are well-documented in various materials, the ripplocations appears to be a unique characteristic of van der materials like SnS₂. These defects are believed to result from local variations in supersaturation during the nucleation and growth of the crystnnal. This type of investigation is expected to yield valuable insights for tailoring the properties of layered materials.<br/><b>References: </b> <br/>1. Eom, T. H. <i>et al.</i> Substantially improved room temperature NO2 sensing in 2-dimensional SnS2 nanoflowers enabled by visible light illumination. <i>J. Mater. Chem. A</i> <b>9</b>, 11168–11178 (2021).<br/>2. Liang, Q., Zhang, Q., Zhao, X., Liu, M. & Wee, A. T. S. Defect Engineering of Two-Dimensional Transition-Metal Dichalcogenides: Applications, Challenges, and Opportunities. <i>ACS Nano</i> <b>15</b>, 2165–2181 (2021).<br/>3. Gruber, J. <i>et al.</i> Evidence for Bulk Ripplocations in Layered Solids. <i>Sci. Rep.</i> <b>6</b>, (2016).