Microplasma-enabled colloidal nitrogen-doped graphene quantum dots for broad-range fluorescent pH sensors

Kurniawan, Darwin; Chiang, Wei Hung

doi:10.1016/j.carbon.2020.05.085

Cited by 69 publications

(80 citation statements)

References 66 publications

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“…The corresponding histogram (figure 6(c)) was fitted with a normal distribution, yielding average heights of 4.49±2.21 nm and 6.00±2.35 nm to as-synthesized GQDs produced by PD and ND, respectively. These results indicate that the structure of synthesized GQDs for both cases consists of a few layers of graphene, consistent with our previous result (Kurniawan & Chiang 2020). As with TEM measurements (figure 5(d)), it is also important to note that some aggregation and particle envelopment are observed in the AFM image for the ND case (figure 6c).…”

Section: Gqds Propertiessupporting

confidence: 91%

“…The crystalline structure of the synthesized GQDs from both cases was confirmed from the fast Fourier transform (FFT) images (figure 5c). High-resolution TEM images reveal GQDs lattice spacings of 0.28 and 0.24 nm, corresponding to the (002) and (1120) planes of graphite (Kumar et al 2018) and graphene (Kurniawan & Chiang 2020) respectively for the PD case, as depicted in figure 5(c). It is difficult to obtain an accurate lattice spacing for the ND case due to particle agglomeration.…”

Section: Gqds Propertiesmentioning

confidence: 99%

“…With these advantages, microplasmas have been exploited to synthesized GQDs or carbon dots (CDs) with tunable properties using simple carbon-containing precursors (Kurniawan & Chiang 2020, Yang, Pai & Chiang 2019, Wang et al 2015, Joffrion et al 2019, Ma et al 2019. GQDs with a 4.9 nm size have been produced by treating an organosulfate aqueous solution by an atmospheric microplasma jet in ambient air (Yang, Pai & Chiang 2019).…”

Section: Introductionmentioning

confidence: 99%

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Effect of plasma polarity on the synthesis of graphene quantum dots by atmospheric-pressure microplasmas

et al. 2020

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The aim of this study is to optimize the production of colloidal graphene quantum dots (GQD) in an aqueous solution containing sodium dodecyl sulfate (SDS) treated by an argon microplasma jet operated in open ambient air. The plasma has been investigated by optical emission spectroscopy and electrical measurements, and the produced GQDs have been studied by Raman spectroscopy, photoluminescence, UV-visible absorption, transmission electron microscopy and atomic force microscopy. We mainly focus on the influence of the polarity of the voltage applied to generate the microplasma. Although the deposited power is higher when using a positive polarity, the energy efficiency is also higher thanks to a faster synthesis rate. To understand the underlying mechanisms, we reproduced the experiments with the addition of H 2 O 2 in the aqueous solution. Results show that the GQD synthesis operates in two steps with SDS fragmentation followed by an electrolysis-related process. We demonstrate that the positive polarity performs better due to higher fragmentation rate.

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Section: Gqds Propertiessupporting

confidence: 91%

Section: Gqds Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of plasma polarity on the synthesis of graphene quantum dots by atmospheric-pressure microplasmas

et al. 2020

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“…This process of varying pH is highly ascribed to the protonation and deprotonation of the free zig-zag or transmission sites of GQDs under alkaline and acidic conditions, thereby affecting the PL wavelength. 85,86 The excitation-dependent and excitation-independent PL behavior of GQDs are still in debate. In the literature, different mechanisms were reported for both excitation-dependent and independent PL emission of GQDs.…”

Section: Optical Propertiesmentioning

confidence: 99%

“…117 The doping and co-doping of GQDs generates additional coordination sites and provides more defects in the structure of prepared GQDs which eventually improves the physical and chemical properties, for example, chemical reactivity, optical properties, and electronic framework of GQDs by tuning their intrinsic properties. 85,120 These heteroatom doped GQDs based biosensors have thus provided a new platform for early diagnosis of several diseases, improved biological agents, bioenvironmental monitoring, and safety assessment. Therefore, these GQDs become suitable probes for various sensing applications.…”

Section: Sensing Applicationmentioning

confidence: 99%

Recent advances in heteroatom-doped graphene quantum dots for sensing applications

2021

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Monochromatic Blue and Switchable Blue‐Green Carbon Quantum Dots by Room‐Temperature Air Plasma Processing

Weerasinghe

Scott

Deshan

et al. 2021

Adv Materials Technologies

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Carbon quantum dots (CQDs, C‐dots or CDs) are an emerging type of nanomaterial which has received immense attention due to their numerous applications. However, most of the reported CQDs in literature typically emit single emission peak under an excitation. Multipeak emissions without any complicated techniques will be ideal for various applications in the fields of ratiometric sensing, optoelectronics, and multifunctional bio‐imaging systems. Here, a fast, effective, and single‐step method is developed for the bulk synthesis of CQDs using atmospheric pressure air plasmas. Structural, morphological, and chemical properties are characterized by advanced analytical techniques. The CQDs have an average diameter of about 3 nm with a narrow size distribution. Emission wavelengths of 470 nm for blue emissive CQDs and 515 nm for green emissive CQDs are observed. Concentration dependency of the CQDs suggests that the switchable mechanism is due to the formation of PTSA excimers. Dual‐emissive CQDs have the potential to be used in bi‐channel ratiometric determination for metal ions, pH sensing, tumor diagnosis and detection, and solid‐state lighting materials. The proof‐of‐principle demonstration of the use of dual‐emissive CQDs (DCQDs) as a fluorescent sensor of Cu2+ ions is also presented to highlight the possible applications.

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Microplasma-enabled colloidal nitrogen-doped graphene quantum dots for broad-range fluorescent pH sensors

Cited by 69 publications

References 66 publications

Effect of plasma polarity on the synthesis of graphene quantum dots by atmospheric-pressure microplasmas

Effect of plasma polarity on the synthesis of graphene quantum dots by atmospheric-pressure microplasmas

Recent advances in heteroatom-doped graphene quantum dots for sensing applications

Monochromatic Blue and Switchable Blue‐Green Carbon Quantum Dots by Room‐Temperature Air Plasma Processing

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