Integrative Approach toward Uncovering the Origin of Photoluminescence in Dual Heteroatom-Doped Carbon Nanodots

Abstract

Carbon nanodots (CDs) were initially synthesized by dehydrating carbohydrates using a commercial household microwave (700 W). To prepare BN-CD, 960 mg of citric acid (5.0 mmol, Aldrich) and 310 mg of boric acid (5.0 mmol) were dissolved in 10 mL of water. To this transparent solution, 347 µL of EDA (5.0 mmol) was added under vigorous stirring for 2 min. The solution was placed into a microwave oven and heated for 2 min, and a yellow solid was obtained after cooling to room temperature. The solid was diluted in 5.0 mL of water. The yellow suspension was dialyzed (SpectraPore MWCO 500 -1,000) for 2 days to remove salts and unreacted chemicals. To synthesize N-CD, microwave pyrolysis was performed in the absence of boric acid. BN-CD0.5 and BN-CD2 were prepared with 2.5 mmol (0.5 equiv. of citric acid and ethylene diamine) and 10 mmol (2 equiv. of citric acid and ethylene diamine) of boric acid, with the same concentrations of other precursors as described above. Non-doped plain CD was synthesized with 5 mmol of citric acid through hydrothermal method at 180 o C for 6 hr. B-CD was synthesized with 5 mmol of boric acid and citric acid.

The Role of Glutathione and Ethanol in Dictating the Emission Dynamics of Natural Resources‐Derived Highly Luminescent Carbon Nanodots

“…At the first place, the inspection of the Kohn‐Sham orbital contours for the frontier MOs, which are depicted in Figure S3 for pyrrolopyridine and Figure S4 for imidazopyridine along with the corresponding energies reveal that they are mainly π ‐type orbitals delocalized over the pyrrolopyridine and imidazopyridine units respectively. In the both cases, the highest intensity transitions are found to be a π−π* type, predominantly between the HOMO and LUMO, which supports the observation of π−π* nature for the main absorption band, contrary to common assignment of n−π* transition . Interestingly, LUMO of either pyrrolopyridine or imidazopyridine the charge density over pyrrolic/imidazolium nitrogen(s) is decreased significantly in comparison to HOMO, which suggest that within increase solvent polarity the hypsochromic shift may be observed, which is experimentally also observed and termed as n−π* absorption band.…”

Excitons in Carbonic Nanostructures

“…However, their properties can be modified dramatically if different heteroatoms are included into their structures as the components of precursors during their synthesis (doping) or by binding after the synthesis (passivation). Doping with nitrogen [87,95], sulfur [96], and, less frequently, by phosphorous [97] and boron [98,99] atoms is shown to increase dramatically the fluorescence quantum yield. The most popular nitrogen-doped structures are formed of citric acid as a carbon source with the addition of ethylene diamine, urea, and amino acids as the source of nitrogen.…”

Customizing the Electrochemical Properties of Carbon Nanodots by Using Quinones in Bottom‐Up Synthesis

“…CNDs have already been employed in biological applications and (photo)catalysis and for preparing inexpensive environmentally friendly mesoscopic solar cells and light emitting diodes . However, although much effort has been put into improving their (optical) performance, especially in the blue and green spectral regions, there is much room for improvement before CNDs catch up with inorganic quantum dots (CdSe, CdS, and PbTe) . Nonetheless, CNDs hold great potential for the following reasons: 1) They can be synthesized from a variety of starting materials through different procedures, 2) their surface can be easily modified through various post‐synthetic procedures, and 3) they are highly soluble in water (and in most organic solvents) .…”