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

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