In short: graphene quantum dots are particles a few nanometers across, made from graphene sheets of pure carbon. At this size, the way they interact with light and electrons changes and they disperse easily in water, so they can be used in ways that flat graphene cannot.
1. What GQDs are
Graphene quantum dots (GQDs) are carbon materials made by breaking graphene down into particles measured in nanometers (one millionth of a millimeter). They consist of one or a few layers of graphene. In research, they are generally described as a few to a dozen or so nanometers in size; J.C. Technology’s GQDs are smaller than 5 nm.
While graphene sheets are flat, two-dimensional materials, GQDs are treated as zero-dimensional “dots” that are tiny in every direction. For graphene itself, see What is graphene?
2. Why “quantum dots”?
When a material is made only nanometers in size, the space in which its electrons can move becomes very small, and the energy levels the electrons can take change. This is called the quantum confinement effect, and particles small enough to show it are called quantum dots.
Large graphene sheets conduct electricity well but hardly glow in a particular color when exposed to light. When the particles are made very small, however, an energy gap (band gap) opens and they begin to emit fluorescence under light. The color depends on the particle size and the condition of the surface. This fluorescence is one of the main reasons GQDs attract attention in research.
3. GQDs vs. graphene
| Graphene | Graphene quantum dots | |
|---|---|---|
| Shape | Flat sheet (2D) | Nanometer-sized particles (0D) |
| Size | Lateral size from hundreds of nanometers to centimeters | A few to a dozen or so nanometers (ours: under 5 nm) |
| Electronic properties | No band gap; highly conductive | A band gap opens; emits fluorescence |
| Dispersion in water | Poor | Often good, thanks to functional groups at the edges |
| Main uses | Batteries, heat management, composites, textiles | Adding functions to materials (textiles, films, cosmetic ingredients); fluorescence research |
Although both come from the same carbon sheet, the difference in size leads to different uses. Because GQDs are tiny and easy to mix into liquids, they are well suited to being compounded into fibers and plastics or added to liquid ingredients.
4. Other quantum dots
The term “quantum dots” is also used in televisions and displays. The discovery and synthesis of quantum dots was recognized with the 2023 Nobel Prize in Chemistry (Moungi Bawendi, Louis Brus and Alexei Ekimov).
| Type | Material | Characteristics |
|---|---|---|
| Graphene quantum dots (GQD) | Carbon (with a graphene layer structure) | Carbon material without heavy metals. Disperses easily in water; chemically stable |
| Carbon dots (CD, CQD) | Carbon (including particles without a clear layer structure) | Spherical carbon nanoparticles. Closely related to GQDs in research; the boundary between the two terms is not clear-cut |
| Semiconductor quantum dots | Compounds of cadmium, selenium, indium, etc. | Bright emission; used commercially in displays. Some contain heavy metals |
Because GQDs are made of carbon, they contain no heavy metals — a key difference from semiconductor quantum dots. J.C. Technology’s GQDs are free of highly toxic metals such as chromium and lead.
5. Key properties
- Extremely small: particles only a few nanometers across mix evenly into fibers, plastics and liquids.
- Water-dispersible: oxygen-containing functional groups are often attached at the edges, making them easy to disperse in water.
- Chemically stable: with a carbon framework, they resist acids and alkalis and have a stable structure.
- Fluorescent: they glow under light, and research is exploring their use as markers and sensors.
- Large surface area: the small particle size means a large surface area per unit weight.
* Properties vary with the production method, size and surface functional groups.
6. How they are made
| Approach | How it works | Characteristics |
|---|---|---|
| Top-down (cutting) | Cutting larger carbon materials — graphene, graphene oxide, carbon fibers — into small pieces | Research often uses oxidation with strong acids, hydrothermal or electrochemical treatment |
| Bottom-up (building) | Heating small molecules such as citric acid to build up a carbon network | Easier to control size, but particles without a clear layer structure also tend to form |
J.C. Technology produces its GQDs by a purely physical method that uses no strong acids, at its own R&D and manufacturing base in China.
7. Uses
Uses being explored in research
- Fluorescent markers (bioimaging) and sensors
- Optical and electronic components such as LEDs and solar cells
- Catalysts
* Includes uses still at the research stage.
What J.C. Technology supplies
We supply GQDs as an ingredient that adds functional performance to materials.
- Fibers · Nonwovens
Functional fibers
Polyester and nylon staple fibers, fleece and nonwovens, used for underwear, children’s clothing, bedding and care linens.
- Packaging
Functional films
Compounded into films such as food cling film.
- Cosmetics
Ingredients
We are developing their use as an ingredient in shampoos, body washes and more.
In the Japanese market, textiles containing our GQDs are offered with five functions: antibacterial and odor-resistant, antiviral, anti-mite, anti-mold and far-infrared emission. The level of performance depends on the application and formulation. See our graphene quantum dots business page for details.
* These functions describe the fiber itself, as used for textile products in the Japanese market. They are not claims that the product protects people from bacteria, viruses or disease. Claims that may be made for products sold outside Japan depend on local regulations (for example, the U.S. EPA and the EU Biocidal Products Regulation). Please consult us for each market.
8. Safety
GQDs are made of carbon and, unlike semiconductor quantum dots, do not use heavy metals such as cadmium. J.C. Technology’s GQDs are an inorganic material free of highly toxic metals such as chromium and lead.
When handling the powder or dispersion in factories, ventilation and masks are recommended to avoid inhalation, as with other nanomaterials. If you are considering GQDs for your products, please contact us and we will provide information suited to your application.
9. FAQ
- What are graphene quantum dots, in simple terms?
- They are graphene sheets — carbon atoms arranged in hexagons — made into particles a few nanometers across. At this size, properties such as how they interact with light and electrons differ from those of the sheet.
- How do graphene quantum dots differ from graphene?
- Graphene is a flat sheet; graphene quantum dots are that sheet made into particles a few nanometers across. As particles, a band gap opens so they emit fluorescence, and they disperse more easily in water.
- Why are they called “quantum dots”?
- When a material is made only nanometers in size, the quantum confinement effect changes the energy levels its electrons can take. Particles small enough to show this effect are called quantum dots.
- Are they the same as the quantum dots used in TVs?
- No. Quantum dots in TVs and displays are mainly semiconductor particles containing elements such as cadmium or indium. Graphene quantum dots are made of carbon and do not use heavy metals.
- How do they differ from carbon dots?
- Both are carbon nanoparticles and are treated as closely related in research. Generally, particles with a graphene layer structure are called graphene quantum dots and spherical particles without a clear layer structure are called carbon dots, but the boundary is not clear-cut.
- What are graphene quantum dots used for?
- In research, they are being explored for fluorescent markers, sensors, LEDs, solar cells and catalysts. J.C. Technology supplies them as an ingredient that adds functional performance to fibers, nonwovens, films and cosmetic ingredients.
- Can I buy graphene quantum dots or use them in my products?
- Yes. J.C. Technology supplies graphene quantum dots as a raw material and also provides fibers, films and finished products on an OEM or private-label basis. Please contact us with your application and volume. We can communicate in English, Japanese and Chinese.
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