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

doi:10.1149/2.1211904jes

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

School of Advanced Science and Engineering

Research output: Contribution to journal › Article › peer-review

11 Citations (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 language	English
Pages (from-to)	D162-D167
Journal	Journal of the Electrochemical Society
Volume	166
Issue number	6
DOIs	https://doi.org/10.1149/2.1211904jes
Publication status	Published - 2019

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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title = "Mechanism of electrolytic reduction of SiO2 at liquid Zn cathode in molten CaCl2",

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.",

author = "Yuanjia Ma and Akifumi Ido and Kouji Yasuda and Rika Hagiwara and Takayuki Homma and Toshiyuki Nohira",

note = "Funding Information: This study was partially supported by Core Research for Evolutionary Science and Technology (CREST) from the Japan Science and Technology Agency (JST); Grant-in-Aid for Scientific Research A, Grant Number 16H02410, from the Japan Society for the Promotion of Science (JSPS); the Kato Foundation for Promotion of Science; and The Joint Usage/Research Center for Zero Emission Energy Research (ZE28A12), Institute of Advanced Energy, Kyoto University. Publisher Copyright: {\textcopyright} 2019 The Electrochemical Society.",

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doi = "10.1149/2.1211904jes",

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T1 - Mechanism of electrolytic reduction of SiO2 at liquid Zn cathode in molten CaCl2

AU - Ma, Yuanjia

AU - Ido, Akifumi

AU - Yasuda, Kouji

AU - Hagiwara, Rika

AU - Homma, Takayuki

AU - Nohira, Toshiyuki

N1 - Funding Information: This study was partially supported by Core Research for Evolutionary Science and Technology (CREST) from the Japan Science and Technology Agency (JST); Grant-in-Aid for Scientific Research A, Grant Number 16H02410, from the Japan Society for the Promotion of Science (JSPS); the Kato Foundation for Promotion of Science; and The Joint Usage/Research Center for Zero Emission Energy Research (ZE28A12), Institute of Advanced Energy, Kyoto University. Publisher Copyright: © 2019 The Electrochemical Society.

PY - 2019

Y1 - 2019

N2 - 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.

AB - 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.

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

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