Mechanism of electrolytic reduction of SiO2 at liquid Zn cathode in molten CaCl2

Yuanjia Ma, Akifumi Ido, Kouji Yasuda, Rika Hagiwara, Takayuki Homma, Toshiyuki Nohira

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1 Citation (Scopus)

Abstract

The reaction mechanism of electrolytic reduction of SiO2 at a liquid Zn cathode in molten CaCl2 was investigated with the aim of establishing a new production process of solar-grade Si. Three types of Zn/SiO2 contacting electrodes were prepared depending on the objectives. Cyclic voltammetry suggested two reduction mechanisms of SiO2 at a Zn electrode. One is a direct electrolytic reduction that proceeds at potentials more negative than 1.55 V vs. Ca2+/Ca. The other is an indirect reduction by liquid Ca-Zn alloy at potentials more negative than 0.85 V. The both reduction mechanisms were confirmed to proceed at 0.60 V by electrolysis and immersion experiments. Impurity analysis by ICP-AES was conducted for the Si prepared by potentiostatic electrolysis at 0.60 V, and confirmed that the concentrations of the metal elements and P were lower than the target levels for primary Si before directional solidification process.

Original languageEnglish
Pages (from-to)D162-D167
JournalJournal of the Electrochemical Society
Volume166
Issue number6
DOIs
Publication statusPublished - 2019 Jan 1

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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