Electrochemical Production of Si without Generation of CO 2 Based on the Use of a Dimensionally Stable Anode in Molten CaCl 2

The current Si production process is based on the high‐temperature (1700 °C) reduction of SiO 2 with carbon that produces large amounts of CO 2 . We report an alternative low‐temperature (850 °C) process based on the reduction of SiO 2 in molten CaCl 2 that does not produce CO 2 . It utilizes an anode material (Ti 4 O 7 ) capable of sustained oxygen evolution. Two types of this anode material, dense Ti 4 O 7 and porous Ti 4 O 7 , were tested. The dense anode showed a better performance. The anode stability is attributed to the formation of a protective TiO 2 layer on its surface. In situ periodic current reversal and ex situ H 2 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 CaCl 2 . 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.