Carbon Dots

Carbon Dots List

Carbon dots are a new type of carbon nanomaterials with the size below 10 nm, which are mainly composed of carbon, hydrogen, oxygen, nitrogen and other elements. Carbon dots are environmentally friendly fluorescent nanomaterials with similar optical properties as conventional semiconductor quantum dots. In addition, compared with the traditional semiconductor quantum dots, carbon dots have the advantages of photobleaching resistance, easy modification and low toxicity. Moreover, carbon dots also have the unique properties of adjustable excitation and emission wavelength range, large two-photon absorption cross section, good light stability and high fluorescence intensity. Therefore, carbon dots have attracted more and more attention.

Applications:

• Bioimaging and biological cell markers field: Many traditional semiconductor quantum dots and organic fluorescent dyes have been applied in the field of bioimaging and biological cell markers. Unfortunately, both traditional semiconductor quantum dots and fluorescent dyes have certain biotoxicity on cells causing cell death, which limits their application in bioimaging and biological cell markers field. Compared with traditional semiconductor quantum dots and organic fluorescent dyes, carbon dots have good optical properties and low cell toxicity, which makes them highly concerned in the bioimaging and biological cell markers field.

Figure 1. An example of carbon dots applied in living cells imaging.

• Analysis and testing field: The luminescent properties of carbon dots are related to the surface situation. When the measured substances are interacted with carbon dots, the compound efficiency of electron hole pairs on the surface can be changed, and the fluorescence signal of the system can be enhanced or quenched. Therefore, the qualitative and quantitative analysis of the measured substances can be realized.
• Photocatalytic field: With the continuous progress of nanoscience, new environment-friendly and economical photocatalysts become favorable, especially in bandgap energy, chemical composition and surface modification. The properties of carbon dots largely depend on the dimension and they have good up-conversion luminescence properties. Furthermore, the response wavelength of carbon dots extends from near-infrared region to blue visible region, which makes them have excellent photocatalytic performance.

Figure 2. An example of carbon dots applied in photocatalytic field.

• The others: In addition to the above application fields, carbon dots are also widely used in the field of solar cells, light-emitting diodes and the others. For example, with the advantages of wide absorption spectrum, narrow emission spectrum, excellent photoelectric conversion performance and high electron mobility, carbon dots have been widely used in solar cells.

Classification:

According to the solubility, carbon dots can be divided into water-soluble carbon dots and oil-soluble carbon dots.

• Water-soluble carbon dots: Water-soluble carbon dots have good water solubility, which is very suitable in aqueous environment applications.
• Oil-soluble carbon dots: Oil-soluble carbon dots have poor solubility in aqueous phase, but have excellent solubility in oil phase. This type carbon dots also have broad applications in many fields.

References

1. Wang Q, Yang H, Zhang Q, et al. Strong acid-assisted preparation of green-emissive carbon dots for fluorometric imaging of pH variation in living cells[J]. Microchimica Acta, 2019, 186(7).
2. Chang Q, Meng X, S. L. Hu, et al. Hydroxyapatite/N-doped carbon dots/Ag₃PO₄ composite for improved visible-light photocatalytic performance[J]. RSC Advances, 2017, 7(48):30191-30198.