Electrochemical Production of Si without Generation of CO2 Based on the Use of a Dimensionally Stable Anode in Molten CaCl2. (26th September 2019)

• Record Type: Journal Article
• Authors: Ge, Jianbang; Zou, Xingli; Almassi, Soroush; Ji, Li; Chaplin, Brian P.; Bard, Allen J.
• Is Part Of: Angewandte Chemie. Volume 131:Number 45(2019)
• Page Start: 16369
• Page End: 16374
• Publication Date: 2019-09-26
• Subjects: Inerte Anoden -- Photoelektrochemie -- Salzschmelzen -- Siliciumabscheidung -- TinO2n−1-Oxide; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201905991
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The current Si production process is based on the high‐temperature (1700 °C) reduction of SiO2 with carbon that produces large amounts of CO2 . We report an alternative low‐temperature (850 °C) process based on the reduction of SiO2 in molten CaCl2 that does not produce CO2 . It utilizes an anode material (Ti4 O7 ) capable of sustained oxygen evolution. Two types of this anode material, dense Ti4 O7 and porous Ti4 O7, were tested. The dense anode showed a better performance. The anode stability is attributed to the formation of a protective TiO2 layer on its surface. In situ periodic current reversal and ex situ H2 reduction could be used for extending the lifetime of the anodes. The findings show that this material can be applied as a recyclable anode in molten CaCl2 . Si wires, films, and particles were deposited with this anode under different cathodic current densities. The prepared Si film exhibited ≈30–40 % of the photocurrent response of a commercial p‐type Si wafer, indicating potential use in photovoltaic cells. Abstract : Filmförderung : Eine hoch elektrisch leitfähige Anode, Ti4 O7, wurde in geschmolzenem CaCl2 ‐CaO‐SiO2 angewendet und produzierte dabei elementares Si ohne Emission von CO2 . In‐situ‐ oder Ex‐situ‐Methoden können genutzt werden, um die Anode zu regenerieren und ihre Lebensdauer zu verlängern. Die abgeschiedenen Si‐Filme zeigen gute photoelektrochemische Eigenschaften.