Electrochemical modification and characterization of topological insulator single crystals

Chaolong Yang, Mattia Cattelan, Neil Fox, Yingkai Huang, Mark Golden, Walther Schwarzacher

Research output: Contribution to journalArticle (Academic Journal)peer-review

3 Citations (Scopus)
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Abstract

We compare electrochemically modified or thiol functionalized single-crystal samples of the topological insulator (TI) Bi2Te0.9Se2.1 to freshly cleaved/air exposed control samples, and use X-ray photoelectron spectroscopy (XPS) to investigate the extent of any surface oxidation. XPS spectra for a TI sample maintained at an appropriate potential for 2 hours demonstrate the feasibility of protecting the TI surface from oxidation while working in an electrochemical environment. Deliberate electrochemical oxidation, in contrast, generates prominent Bi, Te and Se peaks associated with oxidation. However, this change is reversible, as further XPS spectra following electrochemical reduction are similar to those measured for an in-situ cleaved sample. XPS also shows that adsorption of pentanedithiol (PDT) protects the TI surface from oxidation. Cyclic voltammetry shows that PDT adsorption suppresses electrochemical oxidation and reduction, while electrochemical impedance spectroscopy shows that it increases the charge transfer resistance significantly. Our work demonstrate the ability to control and characterize the surface chemistry of single-crystal TIs in an electrochemical environment for the first time.
Original languageEnglish
Number of pages14
JournalLangmuir
Early online date29 Jan 2019
DOIs
Publication statusE-pub ahead of print - 29 Jan 2019

Keywords

  • TOPOLOGICAL INSULATOR
  • Electrochemistry

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