Process for the facile electrosynthesis of graphene from co2

Patent metadata

Field	Value
Publication number	US-2020378014-A1
Application number	US-202016886409-A
Country	US
Kind code	A1
Filing date	May 28, 2020
Priority date	May 28, 2019
Publication date	Dec 3, 2020
Grant date	—

Abstract

The present invention relates to the production of graphene from CO2 through electrolysis and exfoliation processes. One embodiment is a method for producing graphene comprising (i) performing electrolysis between an electrolysis anode and an electrolysis cathode in a molten carbonate electrolyte to generate carbon nanomaterial on the cathode, and (ii) electrochemically exfoliating the carbon nanomaterial from a second anode to produce graphene. The exfoliating step produces graphene in high yield than thicker, conventional graphite exfoliation reactions. CO2 can be the sole reactant used to produce the valuable product as graphene. This can incentivize utilization of CO2, and unlike alternative products made from CO2 such as carbon monoxide or other fuels such as methane, use of the graphene product does not release this greenhouse gas back into the atmosphere.

First claim

1 . A method for producing graphene comprising:
(i) performing electrolysis between an electrolysis anode and an electrolysis cathode in a molten carbonate electrolyte to generate carbon nanomaterial on the cathode; (ii) electrochemically exfoliating the carbon nanomaterial from a second anode to produce graphene.

2 . The method of claim 1 , wherein step (i) is performed without a transition metal on or adjacent to the surface of the cathode.

3 . The method of claim 1 , wherein the electrolysis anode and molten carbonate electrolyte in step (i) do not include a transition metal.

4 . The method of claim 1 , wherein the electrolysis in step (i) is performed in the absence of (a) a transition metal, (b) lithium oxide, or (c) both.

5 . The method of claim 1 , wherein step (i) comprises
(a) heating a carbonate electrolyte to obtain a molten carbonate electrolyte; (b) disposing the molten carbonate electrolyte between an electrolysis anode and an electrolysis cathode in a cell; (c) applying an electrical current to the electrolysis cathode and the electrolysis anode in the cell to electrolyze the carbonate and generate carbon nano-platelets on the electrolysis cathode.

6 . The method of claim 1 , wherein step (ii) comprises performing electrolysis where the electrolysis cathode from step (i) having the carbon nanomaterial is used as an anode to produce graphene.

7 . The method of claim 6 , wherein the electrolysis cathode having the carbon nanomaterial is cooled prior to performing the exfoliation.

8 . The method of claim 1 , wherein step (ii) comprises (a) placing the cathode having carbon nanomaterial from step (i) from the electrolysis cathode as an exfoliation anode in an electrochemical cell containing an exfoliation cathode and an exfoliation electrolyte, (b) applying an electrical voltage between the exfoliation anode and the exfoliation cathode to exfoliate graphene from the exfoliation anode, and (c) optionally, collecting graphene exfoliated from the exfoliation anode.

9 . The method of claim 1 , wherein the electrolyzed carbonate in step (i) is replenished by addition of carbon dioxide.

10 . The method of claim 9 , wherein the source of the added carbon dioxide is one of air, pressurized CO 2 , concentrated CO 2 , a power generating industrial process, an iron generating industrial process, a steel generating industrial process, a cement formation process, an ammonia formation industrial process, an aluminum formation industrial process, a manufacturing process, an oven, a smokestack, or an internal combustion engines.

11 . The method of claim 1 , wherein the electrolysis cathode stainless steel, cast iron, a nickel alloy, or a material that resists corrosion in the presence of the molten carbonate electrolyte, or any combination of the foregoing.

12 . The method of claim 1 , wherein the electrolysis cathode is coated with zinc.

13 . The method of claim 1 , wherein in step (i), electrical current is applied with stepwise increases.

14 . The method of claim 1 , wherein the carbon nanomaterial comprises carbon nanoplatelets.

15 . The method of claim 14 , wherein the carbon nanoplatelets comprise less than about 125 graphene layers.

16 . The method of claim 1 , wherein the molten carbonate electrolyte comprises an alkali metal carbonate, an alkali earth metal carbonate, or any combination thereof.

17 . The method of claim 16 , wherein the alkali metal carbonate or alkali earth metal carbonate is lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, francium carbonate, beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, radium carbonate, or any mixture thereof.

18 . The method of claim 1 , wherein the molten carbonate electrolyte comprises lithium carbonate.

19 . The method of claim 1 , wherein the molten carbonate electrolyte further comprises one or more oxides, and/or one or more oxygen, sulfur, halide, nitrogen or phosphorous containing inorganic salts.

20 . The method of claim 1 , wherein step (ii) is performed in the presence of an exfoliation electrolyte, and the exfoliation electrolyte comprises an aqueous or nonaqueous solution.

21 . The method of claim 20 , wherein the exfoliation electrolyte comprises an aqueous solution of ammonium sulfate.

22 . The method of claim 20 , wherein the exfoliation electrolyte comprises a nonaqueous solution.

23 . The method of claim 20 , wherein the exfoliation electrolyte further comprises a carbonate dissolving solution.

24 . The method of claim 1 , wherein the exfoliation is performed by electrolysis between an exfoliation anode and the exfoliation cathode in an exfoliation electrolyte, where the exfoliation anode and the exfoliation cathode are separated by a membrane, filter, diaphragm or porous separator to isolate the graphene produced within the vicinity of the anode.

25 . The method of claim 1 , wherein the graphene produced comprises less than 10 graphene layers.

26 . The method of claim 1 , wherein the graphene produced comprises less than 5 graphene layers.

27 . The method of claim 1 , wherein the graphene carbon comprises a single layer of graphene.

28 . The method of claim 1 , wherein the coulombic efficiency is greater than about 80%.

29 . The method of claim 1 , wherein the coulombic efficiency is about 100%.

30 . The method of claim 1 , wherein the electrolysis reaction is performed at a current density of between about 5 and about 1000 mA cm 2 .

31 . The method of claim 1 , wherein the graphene carbon nanomaterial has a purity greater than about 95%.

32 . The method of claim 1 , wherein the graphene carbon nanomaterial exhibits a 2D peak in the Raman spectrum at less than 2720 cm 1 .

33 . The method of claim 1 , wherein the graphene produced exhibits a 2D peak in the Raman spectrum between 2679 and 2698 cm −1 .

34 . The method of claim 1 , wherein the graphene produced exhibits a 2D peak in the Raman spectrum at 2679 cm −1 .

35 . The method of claim 1 , wherein step (i) also produces molecular oxygen (O 2 ).

36 . A method for producing carbon nano-platelets comprising:
(a) heating a carbonate electrolyte to obtain a molten carbonate electrolyte; (b) disposing the molten carbonate electrolyte between an electrolysis anode and an electrolysis cathode in a cell, wherein the electrolysis anode and the molten carbonate electrolyte; and (c) applying an electrical current to the electrolysis cathode and the electrolysis anode in the cell to electrolyze the carbonate and generate carbon nano-platelets on the electrolysis cathode without the formation of transition metal nucleation sites on the cathode.

37 . A method for producing carbon nano-onions comprising:
(a) heating a carbonate electrolyte comprising an oxide additive to obtain a molten carbonate electrolyte; (b) disposing the molten carbonate electrolyte between an electrolysis anode and an electrolysis cathode in a cell, wherein the electrolysis anode and the molten carbonate electrolyte do not include a transition metal nucleating agent; (c) applying an electrical current to the electrolysis cathode and the electro

Assignees

• C2Cnt Llc

Inventors

• Licht Stuart

Classifications

• C25B1/135 Primary

  Carbon · CPC title

• Y02C20/40

  of CO2 · CPC title

• C25B15/021

  of heating or cooling · CPC title

• C25B9/09

  Fused bath cells · CPC title

• C25B11/075

  consisting of a single catalytic element or catalytic compound · CPC title