Electro-deposition and re-oxidation of carbon in carbonate containing molten salts

• Main Authors: Happiness V. Ijije, Richard C. Lawrence, Nancy Julius Siambun, Sang, Mun Jeong, Daniel A. Jewell, Di, Hu, Chen, George Zheng
• Format: Article
• Language: English
• Published: Royal Society of Chemistry 2014
• Subjects: QD Chemistry
• Online Access: https://eprints.ums.edu.my/id/eprint/19472/1/Electro.pdf; https://eprints.ums.edu.my/id/eprint/19472/; https://doi.org/10.1039/c4fd00046c

The electrochemical deposition and re-oxidation of solid carbon were studied in CO3(2-) ion-containing molten salts (e.g. CaCl2-CaCO3-LiCl-KCl and Li2CO3-K2CO3) at temperatures between 500 and 800 °C under Ar, CO2 or N2-CO2 atmospheres. The electrode reactions were investigated by thermodynamic analysis, cyclic voltammetry and chronopotentiometry in a three-electrode cell under various conditions. The findings suggest that the electro-reduction of CO3(2-) is dominated by carbon deposition on all three tested working electrodes (Ni, Pt and mild steel), but partial reduction to CO can also occur. Electro-re-oxidation of the deposited carbon in the same molten salts was investigated for potential applications in, for example, direct carbon fuel cells. A brief energy and cost analysis is given based on results from constant voltage electrolysis in a two-electrode cell.