One-step microwave-assisted polyol synthesis of green luminescent carbon dots as optical nanoprobes

Liu, Yi; Xiao, Ni; Gong, Ningqiang; Wang, Hao; Shi, Xin; Gu, Wei; Ye, Ling

doi:10.1016/j.carbon.2013.10.086

Cited by 311 publications

(182 citation statements)

References 29 publications

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“…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.…”

Section: à2mentioning

confidence: 99%

Photobleaching and stabilization of carbon nanodots produced by solvothermal synthesis

Wang

Damm

Walter

et al. 2016

Phys. Chem. Chem. Phys.

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In this work we performed a detailed investigation of the photostability of bottom-up produced carbon nanodots (CDs) prepared from citric acid and urea by solvothermal synthesis. Analytical ultracentrifugation (AUC) reveals that the CDs have a hydrodynamic diameter of o1 nm and a very narrow size distribution.In the community it is widely assumed that CDs are photo-stable. In contrast, we found that CDs exposed to UV-irradiation exhibit noteworthy fluorescence degeneration compared to freshly prepared CDs or CDs stored in the dark, indicating that fluorescence bleaching is caused by a photochemical process. We found that fluorescence intensity decay due to exposure to UV-irradiation is accelerated in the presence of oxygen and identified the surface status of CDs as the decisive factor of fluorescence bleaching of CDs.Based on a discussion on the underlying mechanisms we show how to avoid photobleaching of CDs.

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Section: à2mentioning

confidence: 99%

Photobleaching and stabilization of carbon nanodots produced by solvothermal synthesis

Wang

Damm

Walter

et al. 2016

Phys. Chem. Chem. Phys.

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“…[9][10][11][12][13][14][15] Two general methodologies, either top down 11,16 or bottom up 17,18 have been applied for the synthesis of C-dots. Among these reported synthetic methodologies for the preparation of fluorescent C-dots those that have attracted more attention due to their simplicity have been hydrothermal carbonisation under various conditions of suitable molecular or polymeric precursors, [19][20][21] but also laser ablation 16,22 and arc discharge 23 have been widely employed. One of the main problems in the synthesis of C-dots is the formation of particles with uniform properties and narrow particle size distribution.…”

Section: Introductionmentioning

confidence: 99%

Highly fluorescent C-dots obtained by pyrolysis of quaternary ammonium ions trapped in all-silica ITQ-29 zeolite

et al. 2015

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Abstract.C-dots obtained in homogeneous phase may exhibit a broad particle size distribution. Formation of C-dots within nanometric reaction cavities could be a methodology to gain control on their size distribution. Among the various possibilities, in the present work, the cavities of small pore size zeolites have been used to confine C-dots generated by pyrolysis of the organic structure directing agent present in the synthesis of these crystalline aluminosilicates. To explore this methodology, ITQ-29 zeolite having a Linde type A (LTA) structure was prepared as pure silica with 4-methyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3.2.1-ij]quinolinium as organic structure directing agent. Pyrolysis under inert atmosphere at 550 ºC of a pure-silica ITQ-29 sample (cubic particles of 4 m edge) renders a highly fluorescent zeolite containing about 15 wt.% of carbonised residue. While other small pore zeolite, ITQ-12 (ITW), also renders photoluminescence C-dots under similar conditions, medium or large pore zeolites, such as silicalite (MFI) or pure silica Beta (BEA), failed to produce fluorescent powders under analogous thermal treatment and only decomposition and complete removal of the corresponding quaternary ammonium ion templates was observed for these zeolites. Dissolution of the pyrolysed ITQ-29 zeolite framework and extraction of the carbon residue with ethyl acetate has allowed characterisation of C-dots with particle size between 5-12 nm and a photoluminescence quantum yield of 0.4 upon excitation at 350 nm that is among the highest reported for non surface functionalized C-dots. The photoluminescence varies with the excitation wavelength and is quenched by oxygen. Pyrolysed ITQ-29 powders can act as fluorescent oxygen sensor.

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“…In general, the synthetic methods for C-dots include arcdischarge [2], electrochemical oxidation [3][4][5], laser ablation [6][7][8][9], hydrothermal synthesis [10][11][12][13][14][15], pyrolysis [16][17][18][19], microwave-assisted heating [20][21][22][23][24][25][26], plasma treatment [27], neutralization heating [28], and sonication treatment [29] (Scheme 1). All these synthetic methods allow, up to some extent, preparing moderately high-quality C-dots with relatively high PL performance and small size.…”

Section: Introductionmentioning

confidence: 99%

Characterization and Analytical Separation of Fluorescent Carbon Nanodots

Gong

Liu

et al. 2017

Journal of Nanomaterials

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Carbon nanodots (C-dots) are recently discovered fluorescent carbon nanoparticles with typical sizes of <10 nm. The C-dots have been reported to have excellent photophysical and chemical characteristics. In recent years, the advances in the development and improvement in C-dots synthesis, characterization, and applications are burgeoning. In this review, we introduce the most commonly used techniques for the characterization of C-dots. The characterization techniques for C-dots are briefly classified, described, and illustrated with applied examples. In addition, the analytical separation methods for C-dots (including electrophoresis, chromatography, density gradient centrifugation, differential centrifugation, solvent extraction, and dialysis) are included and discussed according to their analytical characteristics. The review concludes with an outlook towards the future developments in the characterization and the analytical separation of C-dots. The comprehensive overview of the characterization and the analytical separation techniques will safeguard people to use each technique more wisely.

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One-step microwave-assisted polyol synthesis of green luminescent carbon dots as optical nanoprobes

Cited by 311 publications

References 29 publications

Photobleaching and stabilization of carbon nanodots produced by solvothermal synthesis

Photobleaching and stabilization of carbon nanodots produced by solvothermal synthesis

Highly fluorescent C-dots obtained by pyrolysis of quaternary ammonium ions trapped in all-silica ITQ-29 zeolite

Characterization and Analytical Separation of Fluorescent Carbon Nanodots

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