Photoluminescence from amino functionalized graphene quantum dots prepared by electrochemical exfoliation method in the presence of ammonium ions

Hsieh, Chien‐Te; Tzou, Dong-Ying; Hsieh, Keng-Yen; Yin, Ken‐Ming

doi:10.1039/c6ra28742e

Cited by 28 publications

(14 citation statements)

References 36 publications

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“…These peaks confirm the presence of various functional groups such as carbonyl, carboxylic, etc. over the surface of as-synthesized WS 2 -QDs, which is also in good agreement with the FTIR analysis. Further, the BE of O 1s core level peak in the region 528–535 eV can be fitted into doublet peaks at 530.1 and 531.4 eV (shown in Figure d).…”

Section: Resultssupporting

confidence: 87%

In Situ Functionalized Fluorescent WS₂-QDs as Sensitive and Selective Probe for Fe³⁺ and a Detailed Study of Its Fluorescence Quenching

Singh

Mishra

Ali

et al. 2018

ACS Appl. Nano Mater.

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Most of the reports suggest that liquid exfoliated WS2-QDs are unstable; therefore the need of present day is to develop a novel synthesis route for producing long-term stable WS2-QDs. Herein, we report a bottom-up single-step hydrothermal growth of in situ functionalized blue fluorescent WS2-QDs with stable fluorescence in aqueous media without subsequent treatments. Presence of various functional groups over the surface of f-WS2-QDs provides high solubility and stability to f-WS2-QDs in aqueous media preserving its fluorescence. Further, photoluminescence property of f-WS2-QDs has been employed to devise an optical sensor with a high sensitivity (K D ∼ 104 M–1) and selectivity for ferric (Fe3+) ions. Under the optimal condition, response of the sensor is found to be linear in the range of 0–55 μM with a limit of detection (LOD) of 1.32 μM, which is within the maximum permissible level of Fe3+ (∼5.4 μM) in human drinking water by the USEPA. Further, we have also carried out a detailed evaluation on fluorescence quenching kinetics of f-WS2-QDs. Nonlinear behavior of S–V plot and TRPL measurements suggest that quenching is a mixed phenomenon of dynamic as well as static processes. Finally we have proposed a mechanism for fluorescence quenching of f-WS2-QDs in the presence of Fe3+.

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Section: Resultssupporting

confidence: 87%

In Situ Functionalized Fluorescent WS₂-QDs as Sensitive and Selective Probe for Fe³⁺ and a Detailed Study of Its Fluorescence Quenching

Singh

Mishra

Ali

et al. 2018

ACS Appl. Nano Mater.

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“…The PL QYs of the O-NGQDs and B-NGQDs samples were 22.9% and 1% for the emission at 380 nm, respectively. The prominent increase of QY is due to the existence of surface functional species, which has been proven by many studies. ,, The quantum yield (φ) of O-NGQDs is higher than in some previous reports (shown in Table S1). , The average lifetimes were 6.67 and 4.78 ns, respectively.…”

Section: Results and Discussionmentioning

confidence: 72%

Redox Induced Fluorescence On–Off Switching Based on Nitrogen Enriched Graphene Quantum Dots for Formaldehyde Detection and Bioimaging

Sun

Xue

et al. 2018

ACS Sustainable Chem. Eng.

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Tunable optical and fluorescent properties of graphene quantum dots (GQDs) by heteroatom doping and surface functionalization provide tremendous advantages for practical applications. One of these notable issues is the construction of stimuli-responsive GQDs which can be used as smart green nonmetal materials in the field of sensor and biotechnology. In this work, N-doped graphene quantum dots (NGQDs) encapsulated by organic species were obtained through hydrothermal method, of which the quantum yield achieved 22.9%, much higher than that of bare NGQDs (1%). Interestingly, it was found that the functionalized NGQDs exhibited a color oscillation in open air and its fluorescence emission can be reversibly switched "on−off" via redox reactions. Meanwhile, the PL emission would be transformed from excitation-independent to excitation-dependent through modifying the surface states of NGQDs. The origin of PL is then studied, emphatically distinguishing the role of different C−N configurations and surface functional groups. The NGQDs of distinct optical and luminescent characteristic can serve as fluorescent sensors for detection of CH 2 O and probes for bioimaging.

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“…The graphene nanosheets (GN) were separated by size using polymeric filters, and NGQDs were collected through centrifugation. The resulting NGQDs displayed greater amination levels when synthesized with lower applied potentials, as the rate of GN exfoliation was slower, allowing sufficient in situ functionalization with the ammonium ions in the solution 87. Zhang et al.…”

Section: Synthesis Methodsmentioning

confidence: 99%

“…The resulting NGQDs displayed greater amination levels when synthesized with lower applied potentials, as the rate of GN exfoliation was slower, allowing sufficient in situ functionalization with the ammonium ions in the solution. [87] Zhang et al demonstrated the synthesis of boron-functionalized GQDs by doping graphite rods; XPS spectra verified the presence of boron functional groups on the synthesized GQDs. [88] Electrochemical synthesis provides a pathway for more precise synthesis of GQDs compared to hydro/solvothermal methods, by selectively oxidizing the precursor material according to the applied electric potential.…”

Section: Electrochemical Exfoliationmentioning

confidence: 99%

Graphene Quantum Dots and Their Applications in Bioimaging, Biosensing, and Therapy

2019

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the bandgap of graphene may be tunably increased by decreasing the size of the graphene fragment. These graphene particles have been dubbed graphene quantum dots (GQDs), and this tunable electronic structure has been exploited for applications in electronics, energy harvesting, and medicine. [2] One of the most utilized properties of GQDs is their photoluminescence (PL), which describes the emission of light by graphene caused by the excitation of electrons within a GQD upon the absorption of incident photons and the subsequent emission of photons when those excited electrons relax back to a lower energy level. Through various studies, it has been shown that the PL excitation and emission wavelengths can be altered by controlling the size of GQDs, changing the surface properties, or through the introduction of dopants, such as nitrogen or boron, into the carbon lattice. [3][4][5] The tunable PL of GQDs makes them an effective platform for application in bioimaging and biosensing systems since the optimal wavelengths of light dictated by the situation at hand may be harnessed by synthesizing GQDs of appropriate size and/or dopant concentration to elicit the desired PL properties. In addition to dopants within the lattice, oxygen-rich functional groups such as hydroxyl and carboxyl groups exist on the edge of GQDs. These functional groups are a result of oxidation and self-passivation at the surface of GQDs during synthesis, and these polar constituents confer excellent aqueous solubility onto the GQDs, which is beneficial for biological applications. [6] Furthermore, functional groups allow for the facile surface conjugation of useful moieties such as tumor-targeting ligands or chemotherapeutics for use in anticancer drug delivery systems. [7][8][9][10] In many other nanoparticle-based drug delivery systems, a solid core is stabilized by coating the core with polymers, which restricts the number of sites available for chemotherapeutic conjugation on the surface of the nanoparticle. Conversely, GQDs have a large surface area to volume ratio, owing to their planar structure; this allows for higher drug loading and more efficient delivery of chemotherapeutics. Furthermore, π-orbitals that are present throughout the sp 2 -hybridized GQD lattice can bind chemotherapeutics that have an aromatic ring in their structure through π-stacking, without covalent conjugation, further enhancing their ability for drug delivery. [8,11,12] The potential for GQDs to make a substantial impact in medicine has been demonstrated by a myriad of recent developments. Many studies have been aimed at developing novel Graphene quantum dots (GQDs) are carbon-based, nanoscale particles that exhibit excellent chemical, physical, and biological properties that allow them to excel in a wide range of applications in nanomedicine. The unique electronic structure of GQDs confers functional attributes onto these nanomaterials such as strong and tunable photoluminescence for use in fluorescence bioimaging and biosensing, a high loading capacity of aroma...

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Photoluminescence from amino functionalized graphene quantum dots prepared by electrochemical exfoliation method in the presence of ammonium ions

Abstract: This study elucidates how the nitrogen functionalities affect the UV-visible absorption and photoluminescence (PL) emission of N-modified graphene quantum dots (NGQDs).

Cited by 28 publications

References 36 publications

In Situ Functionalized Fluorescent WS₂-QDs as Sensitive and Selective Probe for Fe³⁺ and a Detailed Study of Its Fluorescence Quenching

In Situ Functionalized Fluorescent WS₂-QDs as Sensitive and Selective Probe for Fe³⁺ and a Detailed Study of Its Fluorescence Quenching

Redox Induced Fluorescence On–Off Switching Based on Nitrogen Enriched Graphene Quantum Dots for Formaldehyde Detection and Bioimaging

Graphene Quantum Dots and Their Applications in Bioimaging, Biosensing, and Therapy

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Photoluminescence from amino functionalized graphene quantum dots prepared by electrochemical exfoliation method in the presence of ammonium ions

Abstract: This study elucidates how the nitrogen functionalities affect the UV-visible absorption and photoluminescence (PL) emission of N-modified graphene quantum dots (NGQDs).

Cited by 28 publications

References 36 publications

In Situ Functionalized Fluorescent WS2-QDs as Sensitive and Selective Probe for Fe3+ and a Detailed Study of Its Fluorescence Quenching

In Situ Functionalized Fluorescent WS2-QDs as Sensitive and Selective Probe for Fe3+ and a Detailed Study of Its Fluorescence Quenching

Redox Induced Fluorescence On–Off Switching Based on Nitrogen Enriched Graphene Quantum Dots for Formaldehyde Detection and Bioimaging

Graphene Quantum Dots and Their Applications in Bioimaging, Biosensing, and Therapy

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Resources

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In Situ Functionalized Fluorescent WS₂-QDs as Sensitive and Selective Probe for Fe³⁺ and a Detailed Study of Its Fluorescence Quenching

In Situ Functionalized Fluorescent WS₂-QDs as Sensitive and Selective Probe for Fe³⁺ and a Detailed Study of Its Fluorescence Quenching