Carbon Nanotube Synthesis via the Calciothermic Reduction of Carbon Dioxide with Iron Additives

Abstract

The novel fabrication of multi-walled carbon nanotube (MWCNT)/cementite (Fe3C) nanocomposites was demonstrated via the calciothermic reduction of carbon dioxide (CO2) through electrolysis in molten CaCl2/CaO with iron additives at 1173 K. In this technique, CO2 generated from a graphite anode is reduced to carbon with a metallic calcium reductant formed on a graphite cathode via electrolysis in molten salt. Calciothermic reduction without iron additives resulted in the formation of onion-like carbons (OLCs) with spherical graphite layers and thin graphite sheets. In contrast, MWCNT/Fe3C nanocomposites and OLCs were successfully fabricated via calciothermic reduction with iron additives through their catalytic activities

Overview of CO2 capture and electrolysis technology in molten salts: operational parameters and their effects

“…Overall, one possible theory is that metal oxide additives are reduced to metal and then serve as the active sites for the formation of carbon nanotubes or nanofibers. 44,55,92,94,95…”

“…44 Another interesting case is that Fe ions could successfully combine with produced carbon to synthesize MWCNT/Fe 3 C nanomaterial at 900 °C under 3.1 V with iron melt in the electrolytes. 94 GeO 2 is another example. 95 Soluble GeO 2 was electrochemically reduced to Ge and deposited on the cathode with carbon, and during this process, Ge anchored on the ends and the inner wall of formed carbon to grow carbon nanotubes.…”

“…Overall, one possible theory is that metal oxide additives are reduced to metal and then serve as the active sites for the formation of carbon nanotubes or nanofibers. 44,55,92,94,95 In addition to metal, oxygen ions in these additives need to be examined since they play a significant role in the splitting reaction and regulate the rates of many reactions, such as the evolution of oxygen on the anode surface and the conversion of CO 2 to CO 3 2− . Therefore, there exists an optimal quantity of additives that should be applied to each system.…”

(Invited) Metal Production in CaCl2-Based Melts

“…[9]. Two kinds of carbon were reported as amorphous carbon with spherical morphology and carbon nano-fiber grown from the cathode surface with the assistance of iron particles (17).…”

“…The global warming gas of CO 2 gas may be decomposed into carbon and oxygen if we can use the non-consumable anode such as 8 mol%Y 2 O 3 -stabilized zirconia (12)(13)(14)(15)(16)(17)(18). Hot CO 2 gas can be supplied directly to the molten CaCl 2 from the industrial steelmaking plant, for example.…”