Synthesis of Type II Ge and Ge-Si Alloyed Clathrates Using Solid-State Electrochemical Oxidation of Zintl Phase Precursors

Andrew Dopilka, Alexander Ovchinnikov, Amanda Childs, Svilen Bobev, Xihong Peng, Candace K. Chan

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Germanium clathrates with the type II structure are open-framework materials that show promise for various applications, but the difficulty of achieving phase-pure products via traditional synthesis routes has hindered their development. Herein, we demonstrate the synthesis of type II Ge clathrates in a two-electrode electrochemical cell using Na4Ge4-ySiy (y = 0, 1) Zintl phase precursors as the working electrode, Na metal as the counter/reference electrode, and Na-ion conducting β″-alumina as the solid electrolyte. The galvanostatic oxidation of Na4Ge4 resulted in voltage plateaus around 0.34-0.40 V vs Na/Na+ with the formation of different products depending on the reaction temperature. When using Na4Ge3Si as a precursor, nearly phase-pure, alloyed type II Ge-Si clathrate was obtained at 350 °C. The Na atoms in the large (Ge,Si)28 cages of the clathrate occupied off-centered positions according to Rietveld refinement and density functional theory calculations. The results indicate that electrochemical oxidation of Zintl phase precursors is a promising pathway for synthesizing Ge clathrates with type II structure and that Si alloying of the Zintl phase precursor can promote selective clathrate product formation over other phases.

Original languageEnglish (US)
Pages (from-to)12363-12372
Number of pages10
JournalInorganic chemistry
Volume61
Issue number31
DOIs
StatePublished - Aug 8 2022

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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