A benign ultrasonic route to reduced graphene oxide from pristine graphite

Soltani, Tayyebeh; Lee, Byeong Kyu

doi:10.1016/j.jcis.2016.09.075

Cited by 97 publications

(47 citation statements)

References 51 publications

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“…The effects of ultra-sonication and magnetic stirring to exfoliate the rGO sheets can also be observed from the surface SEM images (Figure 2(b,c)) and cross sectional images ( Figure 3(a,b)) where the exfoliated rGO layers homogenous dispersion on the copolymer matrix can be seen. Similar kinds of experiments to exfoliate the rGO sheets were also followed by Loryuenyong et al [22] and Soltani and Kyu Lee [23]. However, with the homogeneous dispersion an increasing of conductive channel (reduced graphene oxide fillers) throughout the copolymer matrix from Figure 2(a-e) can be observed.…”

Section: Resultssupporting

confidence: 73%

The effects of conductive nano fillers alignment on the dielectric properties of copolymer matrix

Rahaman

Yaqoob

Kim

2019

Advanced Manufacturing: Polymer & Composites Science

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This research focuses on the improvement of the dielectric and energy harvesting properties of piezoelectric P(VDF-TrFE) copolymer matrix by the alignment of conductive reduced graphene oxide nano fillers. The dispersion and the morphology of the conductive nano fillers on the co-polymer matrix were characterized by scanning electron microscopy which showed a configurational phase transition due to highly conductive nano channel formation, steric hindrance, excluded volume interaction van-der-walls forces between adjacent reduced graphene oxide sheets. Five different piezoelectric nanocomposites were prepared by varying the reduced graphene oxide contents in P(VDF-TrFE) matrix to realize its optimum concentration in the matrix. From our analysis, we observed that, an optimized morphological structure plays a vital role in the formation of polar electroactive b phase on the co-polymer matrix through the good dispersion, filler alignment and interfacial interaction of reduced graphene oxide nano fillers. The as prepared nanocomposite film showed an enhanced crystallinity (50 $ 52%), dielectric constant (72 at 1 kHz), piezoelectric charge constant (À23 pC/N) with an output power of 3.2 mW at 1.8 MX load for 2 N mechanical force. All the outputs were observed without applying poling process. We expect that our synthesized self-poled nanocomposite can be a useful candidate for energy harvesting applications.

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Section: Resultssupporting

confidence: 73%

The effects of conductive nano fillers alignment on the dielectric properties of copolymer matrix

Rahaman

Yaqoob

Kim

2019

Advanced Manufacturing: Polymer & Composites Science

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“…4. The C 1s deconvolution spectrum of PEG(aq) exhibits the characteristic peaks of a C-C chain and C-H bond at 284.8 eV and a C-O bond at 286.2 eV [32], as presented in Fig. 4(a).…”

Section: Resultsmentioning

confidence: 99%

Molecular behaviors in thin film lubrication—Part three: Superlubricity attained by polar and nonpolar molecules

Halmans

2018

Friction

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In thin-film lubrication (TFL), generally, the viscosity of the lubricant and its coefficient of friction (CoF) increase. Finding a method to reduce the CoF in TFL is a significant challenge for tribologists. In the present work, we report a robust superlubricity attained by using polyalkylene glycols (PAGs, polar molecules) and poly-α-olefins (PAOs, nonpolar molecules) as lubricants on steel/steel friction pairs that have been pre-treated by wearing-in with polyethylene glycol aqueous solution (PEG(aq)). A steady superlubricity state with a CoF of 0.0045 for PAG100 and 0.006 for PAO6 could be maintained for at least 1 h. Various affecting factors, including the sliding velocity, normal load, and viscosity of the lubricants, were investigated. Element analysis proved that composite tribochemical layers were deposited on the worn region after the treatment with PEG(aq). These layers were formed by the tribochemical reactions between PEG and steel and composed of various substances including oxides, iron oxides, FeOOH, and Fe(OH) 3 , which contributed to the superlubricity. In addition to the tribochemical layers, ordered layers and a fluid layer were formed by the PAGs and PAOs during the superlubricity periods. All the three types of layers contributed to the superlubricity, indicating that it was attained in the TFL regime. Accordingly, a mechanism was proposed for the superlubricity of the PAGs and PAOs in the TFL regime in this work. This study will increase the scientific understanding of the superlubricity in the TFL regime and reveal, in the future, the potential for designing superlubricity systems on steel surfaces for industrial applications.

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“…The physical phenomenon occurring during ultrasonic processes is acoustic cavitation where the formation, growth, and implosive collapse of the bubbles in liquid takes place. During this process, extremely high temperatures (up to 5000 K) and pressures (≤20 MPa) are produced from the collapse of the generated bubbles, which takes place in less than a nanosecond, achieving extremely high cooling rates . Such unique reaction conditions result in materials with unique properties, good yields, and high crystallinity and homogeneity, under minimal reaction times in comparison to most chemical approaches .…”

Section: Introductionmentioning

confidence: 99%

“…Such unique reaction conditions result in materials with unique properties, good yields, and high crystallinity and homogeneity, under minimal reaction times in comparison to most chemical approaches . Herein, the ultrasonically assisted preparation of rGO/TiO 2 composites at room temperature and under ambient pressure, in the absence of reducing agents, is presented . The as‐prepared composites are then tested for their efficiency in the decomposition and mineralization of a pesticide from the chemical class of pyridine compounds, as well as on the inactivation of highly resistant biological targets.…”

Section: Introductionmentioning

confidence: 99%

“…During this process, extremely high temperatures (up to 5000 K) and pressures (≤20 MPa) are produced from the collapse of the generated bubbles, which takes place in less than a nanosecond, achieving extremely high cooling rates. 35 Such unique reaction conditions result in materials with unique properties, good yields, and high crystallinity and homogeneity, under minimal reaction times in comparison to most chemical approaches. 36 Herein, the ultrasonically assisted preparation of rGO/TiO 2 composites at room temperature and under ambient pressure, in the absence of reducing agents, is presented.…”

Section: Introductionmentioning

confidence: 99%

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Photocatalytic disinfection and purification of water employing reduced graphene oxide/TiO₂ composites

Berberidou

Kyzas

Paspaltsis

et al. 2019

J of Chemical Tech & Biotech

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BACKGROUND Recombination of photogenerated carriers in titanium dioxide (TiO2)‐mediated semiconducting photocatalysis is considered to be the principal obstacle in its unlimited exploitation in practical applications. Hybridization of TiO2 with graphene‐based materials appears to be a highly promising alternative. In this context, reduced graphene oxide (rGO)/TiO2 composites were prepared using a simple ultrasonically assisted route under mild reaction conditions. RESULTS The as‐prepared composites were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectrometry (EDS), Fourier‐transform infrared spectroscopy (FTIR) and nitrogen adsorption–desorption isotherms. Photocatalytic efficiencies of the as‐prepared composites were evaluated employing the pesticide clopyralid as a model pollutant. Initial degradation and mineralization rates obtained in the presence of the as‐prepared composites were, in all cases, higher than the one obtained in the presence of the bare TiO2, with 5% rGO/TiO2 achieving the highest r0 and rDOC values. The as‐prepared composites also were evaluated based on their potential to inactivate bacterial endospores of the Bacillus stearothermophilus species, well‐known for their extraordinary resistance to most inactivation processes. Prevalence of 5% rGO/TiO2 in the inactivation of B. stearothermophilus among all as‐prepared materials was evident, accomplished within 120 min of UV‐A illumination. Real‐time PCR experiments enabled the detection of genomic DNA released during photocatalytic oxidation, in the presence of 5% rGO/TiO2 and UV‐A, suggesting lysis of the outer and inner spore coat caused by the generated ROS. CONCLUSIONS These findings demonstrate the potential of rGO, a low‐cost, nontoxic material to serve as a reliable alternative in the enhancement of TiO2 photocatalytic efficiency in water processing applications. © 2019 Society of Chemical Industry

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A benign ultrasonic route to reduced graphene oxide from pristine graphite

Cited by 97 publications

References 51 publications

The effects of conductive nano fillers alignment on the dielectric properties of copolymer matrix

The effects of conductive nano fillers alignment on the dielectric properties of copolymer matrix

Molecular behaviors in thin film lubrication—Part three: Superlubricity attained by polar and nonpolar molecules

Photocatalytic disinfection and purification of water employing reduced graphene oxide/TiO₂ composites

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A benign ultrasonic route to reduced graphene oxide from pristine graphite

Cited by 97 publications

References 51 publications

The effects of conductive nano fillers alignment on the dielectric properties of copolymer matrix

The effects of conductive nano fillers alignment on the dielectric properties of copolymer matrix

Molecular behaviors in thin film lubrication—Part three: Superlubricity attained by polar and nonpolar molecules

Photocatalytic disinfection and purification of water employing reduced graphene oxide/TiO2 composites

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Photocatalytic disinfection and purification of water employing reduced graphene oxide/TiO₂ composites