Bandgap engineering of nanosized carbon dots through electron-accepting functionalization

Choi, Jongwan; Kim, Nakjoong; Oh, Jin‐Woo; Kim, Felix Sunjoo

doi:10.1016/j.jiec.2018.04.018

Cited by 28 publications

(24 citation statements)

References 52 publications

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“…Choi et al prepared nano-sized C-Dots via oxidation and hydrothermal reaction followed by the introduction of an electron-accepting functional group of nitro (-NO 2 ) and nitrile (-CN) to the C-Dots to control the band-gap energy and frontier molecular orbital energy levels (Choi et al, 2018). The functionalized process was reported not affecting the particle size of the C-Dots because the diameter of the C-Dots can be easily manipulated by the reaction time and pore size of the filters.…”

Section: Surface-related Defective Sitesmentioning

confidence: 99%

A Review on Multifunctional Carbon-Dots Synthesized From Biomass Waste: Design/ Fabrication, Characterization and Applications

et al. 2021

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Carbon-Dots (C-Dots) have drawn much attention in recent years owing to their remarkable properties such as high biocompatibility, low toxicity, nano-scale size, and ease of modification with good tuneable photoluminescence performance. These unique properties have led C-Dots to become a promising platform for bioimaging, metal ion sensing and an antibacterial agent. C-Dots can be prepared using the top-down and bottom-up approaches, in which the latter method is commonly used for large scale and low-cost synthesis. C-Dots can be synthesized using sustainable raw materials or green biomass since it is environmentally friendly, in-expensive and most importantly, promotes the minimization of waste production. However, using biomass waste to produce high-quality C-Dots is still a matter of concern waiting for resolution, and this will be the main focus of this review. Fundamental understanding of C-Dots such as structure analysis, physical and chemical properties of C-Dots, various synthesis methodology and type of raw materials used are also discussed and correlated comprehensively. Additionally, factors affecting the bandgap of the C-Dots and the strategies to overcome these shortcomings are also covered. Moreover, formation mechanism of C-Dots focusing on the hydrothermal method, option and challenges to scale up the C-Dots production are explored. It is expected that the great potential of producing C-Dots from agricultural waste a key benefit in view of their versatility in a wide range of applications.

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Section: Surface-related Defective Sitesmentioning

confidence: 99%

A Review on Multifunctional Carbon-Dots Synthesized From Biomass Waste: Design/ Fabrication, Characterization and Applications

et al. 2021

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“…High‐resolution XPS spectra of N1s (Figure D) shows three characteristic peaks at 399.0, 401.6, and 405.8 eV. The intensities of the peaks at 399.9 and 401.6 eV is lower, corresponding to graphite nitrogen, which is formed by the substitution of some carbon atoms in the products by nitrogen atoms, and the peak at 405.8 eV corresponds to ─NO 2 .…”

Section: Resultsmentioning

confidence: 99%

“…However, there are slight differences on this performance: the emission relations of the peak red‐shift magnitude is FCNPs‐HE > FCNPs‐OS > FCNPs‐AO and the relations of fluorescence intensity at the maximum emission wavelength is FCNPs‐AO > FCNPs‐HE > FCNPs‐OS (FI FCNPs‐AO /FI FCNPs‐HE /FI FCNPs‐OS = 3.35/3.04/1). The possible reason is, on one hand, the content of N and O in FCNPs‐AO is significantly higher than that of FCNPs‐HE and FCNPs‐OS, which has a higher degree of graphitization and defect rate, and may lead to changes in its band gap; on the other hand, the size and surface state of samples prepared by mixed acid/ultrasonic oxidation method may be relatively consistent, therefore the emission wavelength and intensity of FCNPs‐AO are not as dependent on the excitation wavelength as the samples FCNPs‐HE and FCNPs‐OS.…”

Section: Resultsmentioning

confidence: 99%

A comparative study on the preparation methods and properties of coal‐based fluorescent carbon nanoparticles

Awati

Maimaiti

et al. 2019

Surface & Interface Analysis

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Fluorescent carbon nanoparticles (FCNPs) have broad application prospects in the fields of bioimaging, ion detection, and photocatalysis. In this paper, coal-based FCNPs were prepared by using mixed acid oxidation, hydrogen peroxide etching, and organic solvent extraction methods (marked as FCNPs-AO, FCNPs-HE, and FCNPs-OS, respectively), and the structures and properties of the as-prepared products were compared. It was found that the coal-based FCNPs obtained by three kinds of methods are all aromatic structural nanomaterials linked with oxygen-containing groups. Among them, FCNPs-AO is a kind of hollow annular spherical particles and FCNPs-HE and FCNPs-OS are solid spherical particles. These FCNPs not only have similar fluorescence properties as traditional quantum dots, but also can be photoexcited to generate photogenerated electrons and holes, and it can also suppress the recombination of photogenerated electrons and holes by using its own surface defects. In particular, the electron transport capability of the FCNPs-AO is stronger than that of FCNPs-HE and FCNPs-OS because of its lower charge transfer impedance, so it can be excited to generate more photogenerated electrons and has the best photogenerated carrier separation efficiency. KEYWORDScoal, fluorescent carbon nanoparticles, H 2 O 2 etching method, mixed acid oxidation method, organic solvent extraction method

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“…The adsorption of CQDs-N30-G occurs mainly in the UV region (< 400 nm). However, the absorption regions of YCQDs-N10-Y and CQDs-N20-G extend to the visible region (400-650 nm), and the adsorption is more prominent for CQDs-N10-Y, suggesting more narrowing of the bandgap (Choi et al, 2018).…”

Section: Optical Properties Of Bandgap Tunable Cqdsmentioning

confidence: 97%

Facile and Efficient Fabrication of Bandgap Tunable Carbon Quantum Dots Derived From Anthracite and Their Photoluminescence Properties

et al. 2020

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Low-cost and earth-abundant coal has been considered to have a unique structural superiority as carbon sources of carbon quantum dots (CQDs). However, it is still difficult to obtain CQDs from raw coal due to its compactibility and lower reactivity, and the majority of the current coal-based CQDs usually emit green or blue fluorescence. Herein, a facile two-step oxidation approach (K 2 FeO 4 pre-oxidation and H 2 O 2 oxidation) was proposed to fabricate bandgap tunable CQDs from anthracite. The K 2 FeO 4 pre-oxidation can not only weaken the non-bonding forces among coal molecules which cause the expansion of coal particles, but also form a large number of active sites on the surface of coal particles. The above effects make the bandgap tunable CQDs (blue, green, or yellow fluorescence) can be quickly obtained from anthracite within 1 h in the following H 2 O 2 oxidation by simply adjusting the concentration of H 2 O 2 . All the as-prepared CQDs contain more than 30 at% oxygen, and the average diameters of which are <10 nm. The results also indicate that the high oxygen content only can create new energy states inside the band gap of CQDs with average diameter more than 3.2 ± 0.9 nm, which make the as-prepared CQDs emit green or yellow fluorescence.

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Bandgap engineering of nanosized carbon dots through electron-accepting functionalization

Cited by 28 publications

References 52 publications

A Review on Multifunctional Carbon-Dots Synthesized From Biomass Waste: Design/ Fabrication, Characterization and Applications

A Review on Multifunctional Carbon-Dots Synthesized From Biomass Waste: Design/ Fabrication, Characterization and Applications

A comparative study on the preparation methods and properties of coal‐based fluorescent carbon nanoparticles

Facile and Efficient Fabrication of Bandgap Tunable Carbon Quantum Dots Derived From Anthracite and Their Photoluminescence Properties

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