Systems and methods for making carbon nanostructures

Abstract

Embodiments of the present disclosure relate to methods and systems for providing an electrolysis reaction in a molten carbonate electrolyte to synthesize helical carbon nanostructures (HCNSs). The electrolyte, electrode composition, current density, temperature and additives all may have important roles in the formation of HCNS. With control of these parameters, a variety of specific, uniform high yield HCNS can be synthesized by molten carbonate electrolysis, according to embodiments of the present disclosure.

We claim: 
     
         1 - 22 . (canceled) 
     
     
         23 . A system for making a helical carbon nanostructure (HCNS), the system comprising:
 (a) an anode;   (b) a cathode;   (c) an inter-electrode space that is defined between the anode and the cathode;   (d) a source of current for applying a current density that is at least 0.2 A / cm 2  across the electrodes;   (e) a source of heat for regulating the inter-electrode space at a temperature of at least about 725° C.;   (f) a source of carbon for introducing a carbon input into the inter-electrode space,   wherein the system is configured to apply at least two of the following parameters: 
 (i) heating the inter-electrode space to at least 725° C. before the step of applying a current; 
 (ii) introducing into the inter-electrode space an electrolyte additive agent; and 
 (iii) introducing iron oxide to the inter-electrode space. 
   
     
     
         24 . The system of  claim 23 , wherein the source of carbon is carbon dioxide gas. 
     
     
         25 . The system of  claim 23 , wherein the current density is at least 0.4 A / cm 2 . 
     
     
         26 . The system of  claim 23 , wherein the temperature is at least about 750° C. 
     
     
         27 . The system of  claim 23 , further comprising an electrolyte that is received within the inter-electrode space. 
     
     
         28 . The system of  claim 23 , wherein the electrolyte is a molten carbonate. 
     
     
         29 . The system of  claim 23 , further comprising an additive within the inter-electrode space, wherein the additive is one or more of a metal oxide, a borate, a sulfate, a nitrate, a phosphate or combinations thereof. 
     
     
         30 . The system of  claim 23 , wherein the HCNS comprises a yield of at least 20% by weight of helical carbon nanotubes (HCNTs). 
     
     
         31 . The system of  claim 23 , wherein the HCNS comprises a yield of at least 20% by weight of double stranded HCNTs. 
     
     
         32 . The system of  claim 23 , wherein the HCNS comprises a yield of at least 20% by weight of braided HCNTs. 
     
     
         33 . The system of  claim 23 , wherein the HCNS comprises a yield of at least 20% by weight of helical nano-platelets (HCNPs). 
     
     
         34 . The system of  claim 33 , wherein the HCNPs comprises one or more structures with a corkscrew shape, a solid tube, a hollow tube and any combinations thereof.