Rational Design of Multi‐Color‐Emissive Carbon Dots in a Single Reaction System by Hydrothermal

Abstract

As an emerging building unit, carbon dots (CDs) have been igniting the revolutionaries in the fields of optoelectronics, biomedicine, and bioimaging. However, the difficulty of synthesizing CDs in aqueous solution with full‐spectrum emission severely hinders further investigation of their emission mechanism and their extensive applications in white light emitting diodes (LEDs). Here, the full‐color‐emission CDs with a unique structure consisting of sp3‐hybridized carbon cores with small domains of partially sp2‐hybridized carbon atoms are reported. First‐principle calculations are initially used to predict that the transformation from sp3 to sp2 hybridization redshifts the emission of CDs. Guided by the theoretical predictions, a simple, convenient, and controllable route to hydrothermally prepare CDs in a single reaction system is developed. The prepared CDs have full‐spectrum emission with an unprecedented two‐photon emission across the whole visible color range. These full‐color‐emission CDs can be further nurtured by slight modifications of the reaction conditions (e.g., temperature, pH) to generate the emission color from blue to red. Finally a flexible LEDs with full‐color emission by using epoxy CDs films is developed, indicating that the strategy affords an industry translational potential over traditional fluorophores.

Carbon-Based Quantum Dots for Supercapacitors: Recent Advances and Future Challenges

“…In some cases, the X-ray diffractometer results of the CDs show the typical graphite peak centered at approximately 20 • dominated by sp 3 hybridization. Surprisingly, it was reported computationally that the hybridization degree of CDs plays a crucial role in bandgap engineering of CDs [75,76]. Thus, the optical and electronic properties of CDs rely on the surface functional groups that can easily be modified through a preparation method.…”

Assembly of Carbon Dots into Frameworks with Enhanced Stability and Antibacterial Activity

“…The high-resolution transmission electron microscopy (HR-TEM) (Fig. 2 b2) analysis revealed that the building block of CDFs exhibited lattice fringes with a d-spacing of 0.21 nm, corresponding to the (100) plane lattice of graphite, which was similar to the classical CDs [ 23 – 25 ]. Therefore, the assembly CDFs do not lose the feature of CDs, which may combine the advantages of both the entire large frameworks and the interior small building blocks.…”

Facile and Sensitive Detection of Nitrogen-Containing Organic Bases with Near Infrared C-Dots Derived Assays

“…Next, we studied the spectroscopic behaviors of the obtained C-dots. The absorption peaks at 235 and 280 nm in the UV–vis spectral are attributed to the n-π* transition of C-NH 2 , and the π-π* transition of C=C/C=N, respectively; while the peaks above 300 nm are attributed to core absorptions of C-dots [ 14 , 15 ] ( Figure 2 d). Compared to the carbon precursor (o-PDA), it is obvious that the UV–vis absorption peak of C-dots at 235 nm significantly decreased, while that at 280 nm greatly increased.…”