Exfoliation of Layered Topological Insulators Bi2Se3 and Bi2Te3 via Electrochemistry

Among layered materials, topological insulators such as Bi2Se3 and Bi2Te3 are lately attracting much attention due to particular electronic properties and, especially with Bi2Te3, excellent thermoelectric properties. Methods of preparation of few-layered nanosheets of Bi2Se3 and Bi2Te3 range from the bottom-up chemical vapor deposition or hydrothermal synthesis from oxide precursors to the top-down mechanical exfoliation and liquid-based exfoliation supported by sonication from the natural bulk crystals. Here, we propose a simple and rapid electrochemical approach to exfoliate natural Bi2Se3 and Bi2Te3 crystals in aqueous media to single/few-layer sheets. The exfoliated materials have been characterized by scanning transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, high-resolution transmission electron microscopy, and Raman spectroscopy in addition to evaluation of their electrochemical properties. This electrochemical procedure represents a simple, reagent-free, and scalable method for the fabrication of single/few-layer sheets of these materials.