# US 9,751,766 B1 · One-step synthesis of graphene quantum dots

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- Number: US 9,751,766 B1
- Document ID: US9751766B1
- Status: Granted
- Kind: B1
- Application number: 15/334,695
- Filed: 2016-10-26
- Granted: 2017-09-05
- Earliest claimed: 2014-06-24
- Assignees: University of South Florida
- Applicants: Yiru Qin; Shu-Feng Zhou
- Inventors: Yiru Qin; Shu-Feng Zhou
- Web page: https://patentgrep.com/patent/US9751766B1

## CPC

- C01B 32/184: Preparation
- B82Y 40/00: Manufacture or treatment of nanostructures
- C01B 2204/22: Electronic properties
- Y10S 977/734: Fullerenes, i.e. graphene-based structures, such as nanohorns, nanococoons, nanoscrolls or fullerene-like structures, e.g. WS2 or MoS2 chalcogenide nanotubes, planar C3N4, etc.
- Y10S 977/842: for carbon nanotubes or fullerenes
- Y10S 977/915: Therapeutic or pharmaceutical composition
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

Methods of making graphene quantums dots are provided. The methods can produce graphene quantum dots with a monodisperse size distribution. The graphene quantum dots are produced, via one-pot synthesis, from a graphene source and a strong oxidizing mixture at an elevated temperature. The strong oxidizing mixture can contain one or more permanganates and one or more oxidizing acids. Exemplary permanganates include sodium permanganate, potassium permanganate, and calcium permanganate. Exemplary oxidizing acids include nitric acid and sulfuric acid. The graphene quantum dots can have an average particle size of between about 1 nm and 20 nm and a monodisperse size distribution. For example, the size distribution can have a span about 1 or less and/or a coefficient of variance of about 0.5 or less. About 40% or more of the graphene quantum dots can have a diameter within ±5 nm of the average particle size of the graphene quantum dots.

## Claims

### Claim 1

A method of making graphene quantum dots (GQDs) comprising:
combining a graphene source with a strong oxidizing mixture to form a combination; and
heating the combination to an elevated temperature with respect to room temperature to produce the GQDs,
wherein the GQDs have an average diameter of between 2.0 nm and 10.0 nm and
wherein the graphene source is selected from the group consisting of graphite, carbon black, and combinations thereof.

### Claim 2 (depends on 1)

The method of claim 1, wherein the oxidizing mixture comprises a permanganate selected from the group consisting of potassium permanganate, ammonium permanganate, calcium permanganate, sodium permanganate, and silver permanganate.

### Claim 3 (depends on 1)

The method of claim 1, wherein the strong oxidizing mixture comprises a persulfate selected from the group consisting of sodium peroxomonosulfate, sodium persulfate, potassium peroxymonosufate, and ammonium persulfate.

### Claim 4 (depends on 1)

The method of claim 1, wherein the strong oxidizing mixture comprises an oxidizing acid selected from the group consisting of nitric acid, perchloric acid, chloric acid, chromic acid, and sulfuric acid.

### Claim 5 (depends on 1)

The method of claim 1, wherein the oxidizing mixture comprises at least one permanganate and at least one oxidizing acid.

### Claim 6 (depends on 1)

The method of claim 1, wherein the oxidizing mixture comprises potassium permanganate, nitric acid, and sulfuric acid.

### Claim 7 (depends on 1)

The method of claim 1, wherein the elevated temperature is 100° C. to 200° C.

### Claim 8 (depends on 1)

The method of claim 1, wherein the GQDs have a monodisperse particle distribution.

### Claim 9 (depends on 1)

The method of claim 1, wherein the heating is for a period of time of 2 hours or less.

### Claim 10 (depends on 1)

The method of claim 1, wherein the strong oxidizing mixture comprises one or more oxidizing agents having a standard electrode potential between 1.0 V and 2.5 V.

### Claim 11

A method of making graphene quantum dots (GQDs) comprising:
combining a graphene source with a strong oxidizing mixture to form a combination; and
heating the combination to an elevated temperature with respect to room temperature to produce the GQDs,
wherein the GQDs have a monodisperse particle distribution, and
wherein the graphene source is selected from the group consisting of graphite, carbon black, and combinations thereof.

### Claim 12 (depends on 11)

The method of claim 11, wherein the oxidizing mixture comprises a permanganate selected from the group consisting of potassium permanganate, ammonium permanganate, calcium permanganate, sodium permanganate, and silver permanganate.

### Claim 13 (depends on 11)

The method of claim 11, wherein the strong oxidizing mixture comprises a persulfate selected from the group consisting of sodium peroxomonosulfate, sodium persulfate, potassium peroxymonosulfate, and ammonium persulfate.

### Claim 14 (depends on 11)

The method of claim 11, wherein the strong oxidizing mixture comprises an oxidizing acid selected from the group consisting of nitric acid, perchloric acid, chloric acid, chromic acid, and sulfuric acid.

### Claim 15 (depends on 11)

The method of claim 11, wherein the oxidizing mixture comprises at least one permanganate and at least one oxidizing acid.

### Claim 16 (depends on 11)

The method of claim 11, wherein the oxidizing mixture comprises potassium permanganate, nitric acid, and sulfuric acid.

### Claim 17 (depends on 11)

The method of claim 11, wherein the elevated temperature is 100° C. to 200° C.

### Claim 18 (depends on 11)

The method of claim 11, wherein the heating is for a period of time of 2 hours or less.

### Claim 19 (depends on 11)

The method of claim 11, wherein the strong oxidizing mixture comprises one or more oxidizing agents having a standard electrode potential between 1.0 V and 2.5 V.