A system and process for producing carbon nano-materials is disclosed. A carbonate material such as Li2CO3 is heated via a furnace to transform into molten carbonate. CO2 is bubbled into the molten carbonate. The molten carbonate is subjected to electrolysis by passing current from an anode to a cathode. A transition metal nucleation agent is added to result in nucleation sites that grow carbon nano-materials at the cathode. This process separates oxygen at the anode and carbon nano-materials at the cathode. The characteristics of the carbon nano-material may be controlled by varying current density, feed gas, transition metal composition, temperature, viscosity and electrolyte composition.