E. Celasco; M. Sangermano
Abstract
Graphene (G) presents a huge variety of intriguing properties, as extraordinary electronic transport characteristics. G, thanks to its low chemical reactivity, can also be used as an active support for catalytic nanoparticles. Some possible graphene application could be: its employment in active material ...
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Graphene (G) presents a huge variety of intriguing properties, as extraordinary electronic transport characteristics. G, thanks to its low chemical reactivity, can also be used as an active support for catalytic nanoparticles. Some possible graphene application could be: its employment in active material in electronic devices such as sensors, batteries, supercapacitors, hydrogen storage systems or as fillers to produce multifunctional nanocomposite polymeric materials. In more detail we would like to examine: different approach of reduction and functionalization of in situ reduced graphene oxide obtaining an enhancement of thermal conductivity and an resistivity decrease. Surface modification and functionalization of rGO to improve its dispersion in organic solvent and also polymeric matrix. Copyright © VBRI Press.
Meng Li; Su Dou; Na Feng; Xiong Pu; Weiguo Hu
Abstract
The red phosphorus is considered as a promising anode material for sodium-ion batteries (SIBs) due to its high theoretical capacity of 2596 mAh/g. However, red phosphorus suffers from some limitations, such as low electronic conductivity, and huge volume expansion in the process of discharging. Herein, ...
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The red phosphorus is considered as a promising anode material for sodium-ion batteries (SIBs) due to its high theoretical capacity of 2596 mAh/g. However, red phosphorus suffers from some limitations, such as low electronic conductivity, and huge volume expansion in the process of discharging. Herein, we report a high-performance anode with red phosphorus (rP)/reduced graghene oxide (rGO) nanocomposite via vaporization-condensation method. The resulting nanostructured rP is uniformly distributed on the surfaces of rGO. The obtained rP/rGO anode achieves high reversibility (76.85% initial columbic efficiency), high specific discharge capacity (1582.3 mAh/g at 260 mA/g), stable cycling performances (60.2% capacity retention after 50 cycles), and high rate performances (up to 7800 mA/g current density). These high performances of our nanocomposite materials suggest that the rP/rGO anode is of great potential for future high energy SIBs.
Agnieszka Iwan; Felipe Caballero-Briones; Krzysztof A. Bogdanowicz; José D. O. Barceinas-Sánchez; Wojciech Przybyl; Adam Januszko; Javier A. Baron-Miranda; Ana P. Espinosa-Ramirez; Jesus Guerrero-Contreras
Abstract
Graphene oxide (GO) was synthesized using modified Hummers method. GO films were deposited by doctor blade onto glass slides and Ecoflex® membranes using GO suspensions, or dip-coated onto molecular functionalized glass substrates. Doctor bladed films were studied by optical transmittance, linear ...
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Graphene oxide (GO) was synthesized using modified Hummers method. GO films were deposited by doctor blade onto glass slides and Ecoflex® membranes using GO suspensions, or dip-coated onto molecular functionalized glass substrates. Doctor bladed films were studied by optical transmittance, linear sweep voltammetry and by thermal imaging under applied potential. Dip coated films were reduced with different chemical agents to produce transparent, conductive, reduced graphene oxide (rGO) films that were characterized by optical transmittance, current sensing atomic force microscopy and X-ray photoelectron spectroscopy. Doctor bladed GO films were mechanically stable, with resistances ranging 10 6 to 10 11 ohm depending on the film thickness, which in turn depended on the GO precursor solution concentration. Thermal imaging did not provided evidence of visible voltage-activated conduction. The best reduction treatment to obtain transparent and conductive rGO films comprised a primary reduction with NaBH4 followed by an air annealing at 120 ºC. Conductive atomic force microscopy indicated that rGO film conductivity is governed by the superposition of individual sheet and X-ray photoelectron spectroscopy suggested that the C/O ratio is not determinant for conduction. The better-reduced films had transmittances ca. 85% with sheet resistances around 10 3 ohm/sq, making them feasible as transparent electrodes. Finally, a short discussion about location of GO/rGO in organic solar cells is presented.
K. Hareesh; R. P. Joshi; V. N. Bhoraskar; S. D. Dhole
Abstract
Gold-reduced graphene oxide (AG) nanocomposites were synthesized by one-step gamma radiation assisted method. UV-Visible spectroscopic results showed the disappearance of 230 nm peak and appearance of a peak around 269 nm in AG nanocomposite confirming the reduction of GO, and also a peak around 534 ...
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Gold-reduced graphene oxide (AG) nanocomposites were synthesized by one-step gamma radiation assisted method. UV-Visible spectroscopic results showed the disappearance of 230 nm peak and appearance of a peak around 269 nm in AG nanocomposite confirming the reduction of GO, and also a peak around 534 nm appears confirming the formation of gold nanoparticles (AuNPs). X-ray diffractogram results of AG nanocomposite showed a broad peak around 25° corresponding to reduced graphene oxide and also it showed peak corresponding to face centered cubic structured AuNPs corroborating the UV-Visible spectroscopic results. The decoration of AuNPs of size 6 nm on reduced graphene oxide sheet was revealed by transmission electron microscopic results. X-ray photoelectron spectroscopic results confirmed the removal of oxygen functional groups from graphene oxide and formation of Au 4f in AG nanocomposite. The synthesized AG nanocomposite showed enhanced catalytic reduction of 4-Nitrophenol compared to rGO and AuNPs due to synergistic effect of individual component. Gamma radiation assisted method synthesis of Au-rGO nanocomposite may emerge as one-step synthesis that don’t require high temperature or harsh reducing agent.
Alpana Thakur; Sunil Kumar; Manjula Sharma; V. S. Rangra
Abstract
Graphite oxide (GO) and reduced graphene oxide (RGO) have been synthesized using chemical methods. Prepared graphite oxide and reduced graphene oxide were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. ...
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Graphite oxide (GO) and reduced graphene oxide (RGO) have been synthesized using chemical methods. Prepared graphite oxide and reduced graphene oxide were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. XRD patterns, Raman spectra and FTIR spectroscopy confirms significant structural changes while reducing GO to RGO. The obtained products were further analyzed for their optical and electrical properties using UV-Vis spectroscopy, photoluminescence spectroscopy and four-point probe. RGO has shown excellent electrical conductivity of 1.363×10 4 S/m. The bactericidal action of prepared GO and RGO was also studied against Escherichia coli and Staphylococcus aureus bacteria.
Velram Balaji Mohan; Manfred Stamm;Debes Bhattacharyya; Dongyan Liu; Krishnan Jayaraman
Abstract
This article focuses on the reduction of graphene oxides using different reductants and conditions systematically varying the chemical and physical structure, surface topography and chemistry and film thickness of reduced graphene oxide (rGO) films, with a focus on how these influence the property of ...
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This article focuses on the reduction of graphene oxides using different reductants and conditions systematically varying the chemical and physical structure, surface topography and chemistry and film thickness of reduced graphene oxide (rGO) films, with a focus on how these influence the property of most interest: electrical conductivity. The reduction process restores graphene oxide to a graphene-like structure, improving electrical conductivity while creating changes such as increased roughness, film thickness and new surface functionality. Films with smooth surfaces and minimal thicknesses have been shown to possess higher electrical conductivity. There have been minor changes in d-spacing and improvements in crystal perfection and orientation could be concluded from XRD patterns. Through XPS analysis, a significant decrease in the amount of oxygen functional groups at the surface has been noticed as the films get thinned.
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