[DavidThorne]

CO2 liquifies at modest pressure, even at room temperature.  Using a carbon electrode and a relatively inert electrode would it be possible to decompose CO2 into carbon and oxygen by electrolysis?

[jdurg]

Nope.  CO2 does not conduct electricity.  You need to have a movement of electrons in order to electrolyse something.  That's why when they make fluorine gas, they have to have some potassium-hydrogen-fluoride in the anhydrous HF in order to carry out the electrolysis.  (Because pure HF does NOT conduct electricity).