Prof. Stuart Licht’s group at George Washington University recently published an article in NanoLetters on the use of high temperature electrolysis to convert CO2 into carbon nanotubes (CNTs) (and other morphologies) and O2:
The process takes place at around 800 C in a molten carbonate salt, which can easily absorb CO2 from air or a flue stream as the carbonate is converted to carbon at the cathode in the electrochemical reactor. The process could be run as a STEP process (solar thermal electrochemical process), using the sun to heat the electrolysis solution and provide electricity for the electrochemical reaction.
In addition to providing an useful means of sequestering excess CO2 in the atmosphere in the form of solid carbon, there could be great economic incentive for such a process. This article is cited as saying that CNT’s sell for about $25,000 per ton.