Simple route to highly conductive porous graphene from carbon nanodots for supercapacitor applications

Patent metadata

Field	Value
Publication number	US-2021375559-A1
Application number	US-202117401804-A
Country	US
Kind code	A1
Filing date	Aug 13, 2021
Priority date	Jul 14, 2017
Publication date	Dec 2, 2021
Grant date	—

Abstract

Disclosed herein are methods and compositions directed to a promising class of nanomaterials called organic nanoparticles, or carbon nanodots. The present disclosure provides a facile method for the conversion of biomolecule-based carbon nanodots into high surface area three-dimensional graphene networks with excellent electrochemical properties.

First claim

What is claimed is:

1 . A method for synthesizing a carbon network comprising:
a. dissolving carbon nanodots (CNDs) in a solvent to form a CND slurry; b. casting the CND slurry onto a substrate; c. drying the CND slurry on the substrate to form a CND film; and d. irradiating the CND film with a light beam to convert at least a portion of the CND film into turbostratic graphene.

2 . The method of claim 1 , wherein irradiating the CND film with the light beam is performed at a predetermined temperature in an oxygen-free environment for a predetermined time.

3 . The method of claim 2 , wherein the predetermined temperature is about 200° C. to about 400° C.

4 . The method of claim 2 , wherein the predetermined time is about 1 hour to about 3 hours.

5 . The method of claim 1 , wherein the solvent is an organic liquid.

6 . The method of claim 5 , wherein the organic liquid is N-methyl-2-pyrrolidone (NMP).

7 . The method of claim 6 , wherein the CND slurry has a CND-to-NMP ratio of about 0.3:1 to about 0.9:1.

8 . The method of claim 1 , wherein the light beam is generated by a laser.

9 . The method of claim 8 , wherein the laser is a carbon dioxide laser or an infrared laser.

10 . The method of claim 1 , wherein the power level of the light beam is between about 8 watts (W) and about 13 W.

11 . The method of claim 1 , further comprising synthesizing the CNDs by microwave-assisted thermolysis and annealing.

12 . The method of claim 11 , wherein the thermolysis is performed with a small molecule comprising citric acid and urea.

13 . The method of claim 11 , wherein annealing is performed:
a. at temperatures up to about 400° C.; b. in an oxygen-free environment; c. under a constant argon flow; or d. any combination thereof.

14 . The method of claim 1 , wherein irradiating the CND film removes about 60% of the CND film.

15 . The method of claim 1 , wherein the carbon network is porous.

16 . The method of claim 15 , wherein the carbon network has an average pore size of about 10 nanometers (nm) to about 100,000 nm.

17 . The method of claim 1 , wherein the carbon network has an elemental composition of at least about 40% carbon.

18 . The method of claim 17 , wherein the carbon network has an elemental composition of about 89% carbon, about 8% oxygen, and nitrogen.

19 . The method of claim 1 , wherein the turbostratic graphene has a particle size of about 2 nm to about 50 nm.

20 . The method of claim 1 , wherein the turbostratic graphene has an active surface area of at least about 230 square meters per gram.

Assignees

• Univ California

Inventors

• Strauss Volker
• Kaner Richard B
• El-Kady Maher F

Classifications

• H01G11/86 Primary

  specially adapted for electrodes (carbonisation or activation of carbon for the manufacture of electrodes H01G11/34) · CPC title

• H01G11/36 Primary

  Nanostructures, e.g. nanofibres, nanotubes or fullerenes · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• C01B2204/22

  Electronic properties · CPC title

• H01G11/24

  characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor · CPC title