Premium
Electrochemically Driven Three‐Phase Interlines into Insulator Compounds: Electroreduction of Solid SiO 2 in Molten CaCl 2
Author(s) -
Xiao Wei,
Jin Xianbo,
Deng Yuan,
Wang Dihua,
Hu Xiaohong,
Chen George Z.
Publication year - 2006
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600149
Subject(s) - overpotential , passivation , electrochemistry , electrolyte , silicon , quartz , analytical chemistry (journal) , materials science , dissolution , inorganic chemistry , chemistry , chemical engineering , electrode , metallurgy , layer (electronics) , nanotechnology , chromatography , engineering
The electrochemical reduction of solid SiO 2 (quartz) to Si is studied in molten CaCl 2 at 1173 K. Experimental observations are compared and agree well with a novel penetration model in relation with electrochemistry at the dynamic conductor|insulator|electrolyte three‐phase interlines. The findings show that the reduction of a cylindrical quartz pellet at certain potentials is mainly determined by the diffusion of the O 2− ions and also the ohmic polarisation in the reduction‐generated porous silicon layer. The reduction rate increases with the overpotential to a maximum after which the process is retarded, most likely due to precipitation of CaO in the reaction region (cathodic passivation). Data are reported on the reduction rate, current efficiency and energy consumption during the electroreduction of quartz under potentiostatic conditions. These theoretical and experimental findings form the basis for an in‐depth discussion on the optimisation of the electroreduction method for the production of silicon.