Magnetism of graphene quantum dots

Sun, Yuanyuan; Pan, Hao; Chen, Jie; Zhang, Weili; Fu, Lin; Zhang, Kaiyu; Tang, Nujiang; Du, Youwei

doi:10.1038/s41535-017-0010-2

Cited by 68 publications

(61 citation statements)

References 50 publications

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“…To perform the theoretical study, it was considered CQDs exhibiting the following features: quasi‐spherical morphology with diameters in the range of 1.2‐2.8 nm (AFM), presence of stacked graphitic layers, as well as of disordered carbon (Powder X‐ray Diffraction (PXRD), Raman), presence of oxygenated functional groups (FTIR), and elemental composition typical of CQDs synthesized from CA . Previous studies in the literature have suggested that CQDs are composed of stacked graphene nanoflakes (all layers with same diameter or layers with varying diameter), with functional groups attached to external surface. It was used this relatively simplified picture to create more realistic atomic configurations, exhibiting the observed characteristics in the experiments.…”

Section: Resultsmentioning

confidence: 99%

Fluorescence Based Platform to Discriminate Protein Using Carbon Quantum Dots

et al. 2019

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There is an urgent demand to develop a cheap, fast and robust methodology to sense proteins, since these biomolecules are often used as biomarker responsible for diagnosing of some diseases, such as cancer. In this regard, we report a theoretical and experimental study, as well as a cheap and effective ‘chemical‐nose’ strategy based on carbon quantum dots (CQDs) and metallic cations (M) to discriminate proteins at concentration as low as 50 nM. Thus, the CQDs were firstly synthesized through citric acid thermolysis and their characteristics were fully investigated by UV‐Vis absorption, fluorescence, infrared (FTIR), XPS and Raman spectroscopies and atomic force microscopy (AFM). These results pointed out for quasi‐spherical CQDs with diameters in the range of 1.2‐7 nm, presence of stacked graphitic layers and oxygenated functional groups, as well as disordered carbon. Based on the structural and morphological features, computational simulations were carried out to obtain a better understanding of the atomic structure. Our results evidenced a carbon‐based nanoparticle formed by stacked graphene nanoflakes containing defects due to the presence of functional groups within the graphene layers. Afterwards, a ‘tongue’‐based approach was developed by using three distinct CQDs – M (M=Fe3+, Cu2+ or Ni2+) ensembles, which allowed us to acquire different and reproducible fluorescence patterns for four proteins (bovine serum albumin, hemoglobin, myoglobin and cytochrome C) at 50 nM. Subsequently, the pattern recognition was performed using linear discriminant analysis and 36 samples were correctly identified affording 100% of accuracy.

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Section: Resultsmentioning

confidence: 99%

Fluorescence Based Platform to Discriminate Protein Using Carbon Quantum Dots

et al. 2019

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“…The bond lengths 10C‐7C and 7C‐3C are with same values 1.412 Å in the more stable triplet ground state than the same corresponding length 10C‐7C (1.422 Å) and 7C‐3C (1.40 Å) in singlet ground state. These can be attributed to the stability of the FM structure as well as confirm that the shapes and edges which depends on the bond lengths and angles in the benzene ring affect magnetism in triangulene like other GQDs . Figure presents the optimized structures of triangulene with four transition metals.…”

Section: Resultsmentioning

confidence: 99%

Tailoring the Electronic and Magnetic Properties of Peculiar Triplet Ground State Polybenzoid “Triangulene”

et al. 2018

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In the present work we have studied the structural and electronic properties of recently synthesized elusive free standing triangulene using density functional theory. Triangulene, which is a type of graphene quantum dot, is a molecule with an even number of electrons and atoms but the structure of molecule is such that it is impossible to pair all these electrons. The spins of these two unpaired electrons have two possible orientations: triplet (ferromagnetic) and singlet (antiferromagnetic) state. From the first principles study of free standing triangulene, we found energetically, by koopman's theory of global reactivity descriptors and frequency calculations that triplet (ferromagnetic) is more stable than singlet (antiferromagnetic) which is in good agreement with the previous results. These elementary studies are technologically compatible as open shell graphene quantum dots could be useful in spintronic and magnetic carbon materials. Further we have also studied the influence of magnetic elements Fe, Co, Ni and Cu on triangulene for their applications in spintronics. Our results suggest that the transitional metal (TM) doped graphene quantum dot is interesting for information readout devices where the TM‐ion spin states can be used to store information.

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“…We applied (2) to fit data shown in Figure 4 , and pure GQD (curve c, data factorized with factor 800), respectively. It was shown by Sun et al [27] that pure GQDs demonstrate diamagnetic and paramagnetic properties at low temperature. In their case, the magnetization curve measured at 2 K demonstrated a saturation effect, and it was fit with high accuracy by (1) where the value of the fitting parameter J was about 0.5, that is, with high accuracy equal to the electron spin angular momentum.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Optical, and Magnetic Properties of Graphene Quantum Dots and Iron Oxide Nanocomposites

Sajjad

Makarov

Sultan

et al. 2018

Advances in Materials Science and Engineering

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e combination of nanomaterial graphene quantum dots (GQDs) with magnetic nanoparticles offers a unique set of optical and magnetic properties for future energy and medical applications. We report on the synthesis and engineering of GQDs and iron oxide (Fe 3 O 4 ) nanocomposites (NCs) by using a pulsed laser discharge technique. High-resolution transmission electron microscopy (HRTEM) images showed a high yield of pure GQDs with 2-10 nm diameter. e hexagonal structures and lattice fringes associated with the C-C bond in GQDs were clearly identifiable. e structural and optical changes in GQDs and GQDsFe 3 O 4 NC samples induced by UV light were investigated by the absorption and emission spectroscopy over the deep UV-visible spectral range. e photoluminescence spectra have shown subband π→π * transitions in GQDs-Fe 3 O 4 NC. Magnetic properties of the GQDs-Fe 3 O 4 NC samples have shown room temperature ferromagnetism induced by pure Fe 3 O 4 nanoparticles and from the substantial spin polarized edges of GQD nanoparticles. It is concluded that the observed optical and magnetic properties could be further tailored in the studied nanocomposites for prospective medical applications.

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Magnetism of graphene quantum dots

Cited by 68 publications

References 50 publications

Fluorescence Based Platform to Discriminate Protein Using Carbon Quantum Dots

Fluorescence Based Platform to Discriminate Protein Using Carbon Quantum Dots

Tailoring the Electronic and Magnetic Properties of Peculiar Triplet Ground State Polybenzoid “Triangulene”

Synthesis, Optical, and Magnetic Properties of Graphene Quantum Dots and Iron Oxide Nanocomposites

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