Transport properties of graphene quantum dots in glycerol and distilled water

Goharshadi, Elaheh Kafshdare; Niyazi, Zohreh; Shafaee, Masoomeh; Moghaddam, Monireh B.; Ludwig, Ralf; Namayandeh-Jorabchi, Majid

doi:10.1016/j.molliq.2017.06.089

Cited by 47 publications

(17 citation statements)

References 23 publications

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“…propylene glycol-water mixtures, by Amiri et al [123] for aqueous nanofluids containing 0.001 and 0.002 wt% of amine-treated graphene quantum dots (A-GQD), by Sarsam et al [132] for 0.025-0.10 wt.% dispersions of triethanolamine-treated graphene nanoplatelets in water or by Ma et al [128] for 0.01% and 0.05% loading of f-GnS in silicone oil, for example. Conversely, nanofluids that yield a nonlinear relation between shear stress and shear rate were also obtained in the literature [62,82,84,85,91,93,107,118,124]. The Newtonian or non-Newtonian behavior strongly depends on the…”

Section: Insert Here Table 6 4 Viscosity Enhancement: Impact Of Base Fluids Temperature and Graphene Derivatives Concentrationmentioning

confidence: 93%

“…Viscosity versus shear rate curves (in the range from 20 to 300 s -1 ) showed the Newtonian behavior of studied nanofluids with insignificant differences between the average viscosities of water and measured values for water-based A-GQD nanofluids. Goharshadi et al [124] studied the graphene quantum dots GQD/glycerol nanofluids where the nanoparticles were prepared by one-step green pyrolysis of citric acid. The authors worked at temperatures between 293.15 and 333.15 K, and for concentrations between 0.25 and 2 wt%.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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Graphene-based nanofluids: A comprehensive review about rheological behavior and dynamic viscosity

Hamze

Cabaleiro

Estellé

2021

Journal of Molecular Liquids

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Graphene derivatives are promising nanomaterials for producing nanofluids due to their excellent intrinsic characteristics. Among thermophysical profile, and in addition to thermal properties, relevant property to evaluate the potential of graphene-based nanofluids as efficient and reliable heat transfer fluids is viscosity, and rheological behavior in a wider sense. Therefore, the aim of this review paper is to give a comprehensive overview of the current knowledge and results about the rheological properties of graphene-based nanofluids. After a brief description of the most common methods used for fabricating or extracting graphene derivatives, the main steps of graphenebased nanofluids preparation are introduced. Then, literature results on Newtonian/non-Newtonian behavior as well as variations in apparent dynamic viscosity of suspensions containing graphene derivatives are reviewed, analyzing the effects of shear rate, concentration, base fluids and temperature. Such an analysis is performed distinguishing the different types of graphene derivatives, namely graphene oxide, reduced graphene oxide, pristine graphene, graphene quantum dots, functionalized and doped graphene. Also, the impact of base fluid, temperature, concentration and surfactant on viscosity enhancement of graphene-based nanofluids is graphically and newly presented and discussed. In addition, the current models for viscosity prediction or correlation of those nanofluids are detailed. Finally, challenges and future works are summarized.

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Section: Insert Here Table 6 4 Viscosity Enhancement: Impact Of Base Fluids Temperature and Graphene Derivatives Concentrationmentioning

confidence: 93%

Section: Accepted Manuscriptmentioning

confidence: 99%

Graphene-based nanofluids: A comprehensive review about rheological behavior and dynamic viscosity

Hamze

Cabaleiro

Estellé

2021

Journal of Molecular Liquids

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“…Herein, we designed two solar light active photocatalysts including TiO 2 NPs and TiO 2 /GQDs nanocomposite via a facile hydrothermal process to decompose an anionic azo dye, Reactive Black 5 (RB5), under sunlight irradiation. GQDs was synthesized by pyrolysis of citric acid (CA), similar to our previous work [35]. GQDs are two-dimensional sheets of graphene with a size smaller than 100 nm.…”

Section: Introductionmentioning

confidence: 99%

“…GQDs are two-dimensional sheets of graphene with a size smaller than 100 nm. They are non-toxic, free of heavy metals, having high thermal and electrical conductivity, good dispersibility in different solvents, and photoinduced-electron transfer properties [35].…”

Section: Introductionmentioning

confidence: 99%

Highly efficient solar photocatalytic degradation of a textile dye by TiO2/graphene quantum dots nanocomposite

Niazi

Goharshadi

Mashreghi

et al. 2021

Photochem Photobiol Sci

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Herein, two sunlight responsive photocatalysts including TiO 2 nanoparticles (NPs) and TiO 2 /graphene quantum dots (GQDs) nanocomposite for degrading a textile dye, Reactive Black 5 (RB5), were prepared. The results showed that 100% of 50 ppm RB5 could be degraded by TiO 2 NPs and TiO 2 /GQDs within 60 and 30 min sunlight irradiation, respectively. Hence, much better photocatalytic activity in degradation of RB5 was achieved by TiO 2 /GQDs under sunlight irradiation compared with pure TiO 2 NPs due to its lower band gap (2.13 eV) and electron/hole recombination rate. The photocatalytic degradation mechanism of RB5 by TiO 2 NPs was elucidated by adding some scavengers to the solution. The main reactive species contributing to RB5 degradation were surface hydroxyl radicals. The first-order solar degradation rate constant of RB5 for TiO 2 / GQDs is greater than that of TiO 2 NPs under sunlight illumination.

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“…Moreover, in the applications of transparent conductors or smart windows, the low visible transparency of graphene and graphene oxide is also a serious limitation that needs to be resolved. These drawbacks can be solved by using other graphene‐derived materials, such as GQDs or graphene nanoplatelets, which have similarly excellent properties as graphene or GO, but with significantly improved optical properties . In addition, with their smaller size and lighter weight, the use of GQDs may reduce the applied voltage and improve the yield of EPD.…”

Section: Introductionmentioning

confidence: 99%

Additive‐Free Electrophoretic Deposition of Graphene Quantum Dots Thin Films

Nguyen

Geuli

Yeo

et al. 2019

Chemistry A European J

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The electrophoretic deposition (EPD)o fg raphenebased materials on transparent substrates is highly potential for many applications. Several factorsc an determine the yield of the EPD process,s uch as applied voltage, deposition time and particularly the presence of dispersion additives (stabilisers) in the suspension solution. This study presents an additive-free EPD of graphene quantum dot( GQD) thin films on an indium tinoxide (ITO) glass substrate and studies the deposition mechanism with the variation of the applied voltage (10-50 V) and deposition time (5-25 min). It is found that due to the small size ( % 3.9nm) and high content of deprotonatedc arboxylic groups,the GQDs form as table dis-persion (zeta-potential of about À35 mV) without using additives.T he GQD thin films can be deposited onto ITO with optimal surfacem orphologya t3 0Vin 5min (surfacer oughness of approximately (3.1 AE1.3) nm). In addition, as-fabricated GQD thin films also possess some interesting physico-optical properties, such as ad ouble-peak photoluminescence at about l = 417 and 439 nm, with approximately 98 %v isible transmittance. This low-cost and eco-friendly GQD thin film is ap romisingm aterialf or various applications,f or example,t ransparent conductors, supercapacitors and heat conductive films in smart windows.

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Transport properties of graphene quantum dots in glycerol and distilled water

Cited by 47 publications

References 23 publications

Graphene-based nanofluids: A comprehensive review about rheological behavior and dynamic viscosity

Graphene-based nanofluids: A comprehensive review about rheological behavior and dynamic viscosity

Highly efficient solar photocatalytic degradation of a textile dye by TiO2/graphene quantum dots nanocomposite

Additive‐Free Electrophoretic Deposition of Graphene Quantum Dots Thin Films

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