Nitrogen-doped, carbon-rich, highly photoluminescent carbon dots from ammonium citrate

Abstract

The synthesis of water-soluble nitrogen-doped carbon dots has received great attention, due to their wide applications in oxygen reduction reaction, cell imaging, sensors, and drug delivery. Herein, nitrogen-doped, carbon-rich, highly photoluminescent carbon dots have been synthesized for the first time from ammonium citrate under hydrothermal conditions. The obtained nitrogen-doped carbon dots possess bright blue luminescence, short fluorescence lifetime, pH-sensitivity and excellent stability at a high salt concentration. They have potential to be used for pH sensors, cell imaging, solar cells, and photocatalysis.

Photobleaching and stabilization of carbon nanodots produced by solvothermal synthesis

“…Other factors influencing the fluorescence intensity of CDs are pH and ionic strength of the solvent leading to changes in the surface status of the CDs. 18,[42][43][44] It is also expected that fluorescence photobleaching View Article Online is a consequence of changes in the structure of functional groups at the surface. In contrast to fluorescence intensity changes due to variations in pH or ionic strength, fluorescence degeneration by photobleaching is irreversible.…”

“…The CDs synthesized from ''bottom-up'' are always quasi-spherical without a crystal lattice. These CDs consist of aggregated or cross-linked structures from monomers or linear polymers formed using solvothermal, [15][16][17][18][19][20][21][22] microwave, 11,23,24 or calcination 25 methods.…”

One-step Synthesis of Highly Luminescent Nitrogen-doped Carbon Dots for Selective and Sensitive Detection of Mercury(II) Ions and Cellular Imaging

“…The excitation-independent PL behavior may be the result of less surface defects. 31 Meanwhile, such behaviors can avoid the autofluorescence during practical application such as cell imaging. 31 As shown in Fig.…”

“…31 Meanwhile, such behaviors can avoid the autofluorescence during practical application such as cell imaging. 31 As shown in Fig. S2 and Table S1 (Supporting Information) using quinine sulfate as a reference, 32 the QY of N-CDs was calculated to be 40.5% in 10 mM pH 7 PBS solution with the λex of 350 nm, which was higher than those reported in the literature for N-CDs 29,33,34 and the non-doped CDs (QY = 18%) prepared under the same conditions.…”

Microwave-assisted polyol synthesis of carbon nitride dots from folic acid for cell imaging

“…The N1s spectrum ( Figure 2C) of CNDs exhibited a sole peak at 399.5 eV associated with N-C=N, verifiying the presence of nitrogen in the carbon ring. Note that the N1s spectrum of CNDs differs from that of nitrogen-doped carbon dots, which typically showed N1s peaks originated from C 3 −N and N-H. 22 The PL properties of CNDs Figure 3A presents the UV-Vis absorption and PL emission spectra of the as-prepared CNDs. The UV-Vis spectrum showed an adsorption peak at 270 nm, which was attributed to the n−π* transition.…”