Bismuth telluride topological insulator synthesized using liquid metal alloys: Test of NO2 selective sensing

Abstract

Nanostructured topological insulators (TIs), with high surface area and peculiar charge transport, can be advantageous for gas sensing applications. Here interfaces of liquid gallium alloys are used as reaction media to synthesize highly crystalline bismuth telluride (Bi2Te3), which is a well-known TI. The synthesis via these interfaces is self-driven due to the presence of an autogenous interfacial potential on the liquid gallium-indium alloy (EGaIn). Introducing metal-based cations (Bi3+–HTeO2+ in acidic media) into the interfacial Helmholtz zone results in highly crystalline Bi2Te3 platelets. Due to the non-polar surface of EGaIn liquid, the deposited films can be readily exfoliated. The films exhibit unique morphologies of nanostructured platelet-like branches. Sensors fabricated using Bi2Te3 feature selective and sensitive nitrogen dioxide (NO2) physisorption at low operating temperatures. Overall, utilizing liquid metal interfaces as media to drive reactions, which take advantage of their autogenous surface potential, represents a fast and direct protocol that can be further explored to synthesize a variety of functional nanomaterials. Particularly, the approach offers an opportunity for the creation of TIs which are challenging to achieve using traditional potentiostatic methods.