Gas adsorption efficacy of graphene sheets functionalised with carboxyl, hydroxyl and epoxy groups in conjunction with Stone–Thrower–Wales (STW) and inverse Stone–Thrower–Wales (ISTW) defects

2017 ◽  
Vol 19 (45) ◽  
pp. 30895-30913 ◽  
Author(s):  
Murugan Lalitha ◽  
Senthilkumar Lakshmipathi
Keyword(s):  
Graphene Oxide ◽  
Functional Groups ◽  
Gas Adsorption ◽  
Structural Defects ◽  
Graphene Sheets ◽  
Complete Reduction ◽  
Epoxy Groups

The complete reduction of graphene oxide is difficult to achieve, and hence oxygen-containing functional groups do exist in graphene, along with structural defects.

Fabrication of Homogeneously Dispersed Nanoneedle Manganese Dioxide/Graphene Composite for High-Performance Electrode Use in Supercapacitor

2014 ◽  
Vol 894 ◽  
pp. 8-12
Author(s):  
Myeong Jin Kim ◽  
Ki Ho Kim ◽  
Myeong Yeol Yoo ◽  
Joo Heon Kim
Keyword(s):  
Graphene Oxide ◽  
Specific Capacitance ◽  
Functional Groups ◽  
High Performance ◽  
Reaction Order ◽  
Graphene Sheets ◽  
Fabrication Method ◽  
Reduction Procedure ◽  
Second Stage ◽  
Graphene Composite

Two types of graphene/MnO2 composites were synthesized by different reaction procedures. R-GO/MnO2 was synthesized as follows: first, nanoneedle MnO2 was formed on the GO sheets using various functional groups (GO/MnO2). In the second stage, GO/MnO2 was reduced to graphene/MnO2 (R-GO/MnO2) via the dipping method. rGO/MnO2 was synthesized using a different reaction order: first, graphene oxide was reduced to graphene and nanoneedle MnO2 was formed on graphene sheets. Characterization indicated that the nanoneedle MnO2 structures in the R-GO/MnO2 composite were homogeneously dispersed on graphene sheets, whereas MnO2 in the rGO/MnO2 composite formed aggregates due to absence of functional groups. The R-GO/MnO2 electrode exhibited a specific capacitance as high as 327.5 Fg-1at 10 mVs-1, which was higher than that of the rGO/MnO2 electrode (229.9 Fg-1). It is anticipated that the formation of nanoneedle MnO2 on the GO surface following the reduction procedure could be a promising fabrication method for supercapacitor electrodes.

Chemically fluorinated graphene oxide for room temperature ammonia detection at ppb levels

2017 ◽  
Vol 5 (36) ◽  
pp. 19116-19125 ◽  
Author(s):  
Yeon Hoo Kim ◽  
Ji Soo Park ◽  
You-Rim Choi ◽  
Seo Yun Park ◽  
Seon Yong Lee ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Functional Groups ◽  
Room Temperature ◽  
Gas Adsorption ◽  
Ammonia Sensing ◽  
Charge Distributions ◽  
Ammonia Detection ◽  
Adsorption Energies ◽  
Fluorinated Graphene ◽  
Fluorinated Graphene Oxide

Detection of ppb level ammonia at room temperature is demonstrated using chemically fluorinated graphene oxide (CFGO). Fluorine adatom extremely enhances ammonia sensing capabilities through the changes of the charge distributions on adjacent functional groups, resulting in the variation in gas adsorption energies.

scholarly journals Novel Structures of Functionalized Graphene Oxide with Hydrazide: Characterization and Bioevaluation of Antimicrobial and Cytocompatibility Features

Coatings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 45
Author(s):  
Irina Zarafu ◽  
Carmen Limban ◽  
Cristiana Radulescu ◽  
Ioana Daniela Dulama ◽  
Diana Camelia Nuta ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Functional Groups ◽  
Structural Defects ◽  
Functionalized Graphene ◽  
Functionalized Graphene Oxide ◽  
Cytotoxicity Activity ◽  
Disorder Degree ◽  
The Mean ◽  
Novel Structures ◽  
Scanning Electron

Graphite was oxidized to graphene oxide and activated by thionyl chloride, for further covalently linking three hydrazides with potential biological activity. The obtained materials were characterized by scanning electron microscopy with energy dispersive spectroscopy, Fourier-transform infrared and Raman spectroscopies. The presence of various functional groups specific to graphene oxide (GO) functionalized with different hydrazides was confirmed by spectral data. The ratio between D- and G-bands, observed in Raman spectra, allowed for an evaluation of the disorder degree and the mean crystallite size of the samples. The micrographs highlighted that the samples lead to the occurrence of disorders, probably caused by the sp3 carbons, the formation of oxygen-containing functional groups in the basal planes, and by various structural defects. The new graphene oxide–hydrazide derivatives were tested for their antimicrobial and cytotoxicity activity. Their antimicrobial activity against planktonic and biofilm-embedded cells was inferior to that of free hydrazides, except for GO-3 against planktonic Escherichia coli and GO-2 against Pseudomonas aeruginosa biofilm, demonstrating that further optimization is needed to be able to exploit the huge potential of GO for developing potent antimicrobials.

scholarly journals Elucidation of the function of oxygen moieties on graphene oxide and reduced graphene oxide in the nucleation and growth of silver nanoparticles

RSC Advances ◽  
2016 ◽  
Vol 6 (65) ◽  
pp. 60056-60067 ◽  
Author(s):  
Kaja Spilarewicz-Stanek ◽  
Aneta Kisielewska ◽  
Joanna Ginter ◽  
Karolina Bałuszyńska ◽  
Ireneusz Piwoński
Keyword(s):  
Silver Nanoparticles ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Functional Groups ◽  
Nucleation And Growth ◽  
Graphene Sheets ◽  
Reduced Graphene

The goal of the presented investigation was to study the differences in the decoration of graphene sheets, having various amounts of oxygen containing functional groups, with silver nanoparticles (AgNPs).

scholarly journals Mechanical Properties of Graphene Oxide Coupled by Multi-Physical Field: Grain Boundaries and Functional Groups

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 62
Author(s):  
Xu Xu ◽  
Zeping Zhang ◽  
Wenjuan Yao
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Grain Boundaries ◽  
Functional Groups ◽  
Oxygen Content ◽  
Tensile Fracture ◽  
Hydroxyl Groups ◽  
Molecular Configuration ◽  
Spatial Design ◽  
Out Of Plane

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.

scholarly journals Influence of Multidimensional Graphene Oxide (GO) Sheets on Anti-Biofouling and Desalination Performance of Thin-Film Composite Membranes: Effects of GO Lateral Sizes and Oxidation Degree

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2860
Author(s):  
Bárbara E. Rodríguez ◽  
María Magdalena Armendariz-Ontiveros ◽  
Rodrigo Quezada ◽  
Esther A. Huitrón-Segovia ◽  
Humberto Estay ◽  
...  
Keyword(s):  
Thin Film ◽  
Graphene Oxide ◽  
Size Distribution ◽  
Functional Groups ◽  
Water Flow ◽  
Size Group ◽  
Polymerization Reaction ◽  
Medium Size ◽  
Film Composite ◽  
Thin Film Composite

The influence of the lateral size and the content of graphene oxide (GO) flakes in specific oxygenate functional groups on the anti-biofouling properties and performance of thin-film composite membrane (TFC) was studied. Three different multidimensional GO samples were prepared with small (500–1200 nm), medium (1200–2300 nm), and large (2300–3600 nm) size distribution, and with different degrees of oxidation (GO3 > GO2 > GO1), varying the concentration of the hydrogen peroxide amount during GO synthesis. GO1 sheets’ length have a heterogeneous size distribution containing all size groups, whilst GO2 is contained in a medium-size group, and GO3 is totally contained within a small-size group. Moreover, GO oxygenate groups were controlled. GO2 and GO3 have hydroxyl and epoxy groups at the basal plane of their sheets. Meanwhile, GO1 presented only hydroxyl groups. GO sheets were incorporated into the polyamide (PA) layer of the TFC membrane during the interfacial polymerization reaction. The incorporation of GO1 produced a modified membrane with excellent bactericidal properties and anti-adhesion capacity, as well as superior desalination performance with high water flow (133% as compared with the unmodified membrane). For GO2 and GO3, despite the significant anti-biofouling effect, a detrimental impact on desalination performance was observed. The high content of large sheets in GO2 and small sheet stacking in GO3 produced an unfavorable impact on the water flow. Therefore, the synergistic effect due to the presence of large- and small-sized GO sheets and high content of OH-functional groups (GO1) made it possible to balance the performance of the membrane.

scholarly journals Investigation of Graphene Derivatives on Electrical Properties of Alkali Activated Slag Composites

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4374
Author(s):  
Wu-Jian Long ◽  
Xuanhan Zhang ◽  
Biqin Dong ◽  
Yuan Fang ◽  
Tao-Hua Ye ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electrical Properties ◽  
Mechanical Performance ◽  
Structural Defects ◽  
Alkali Activated Slag ◽  
Mechanical And Electrical Properties ◽  
Reduced Graphene ◽  
Graphene Derivatives ◽  
Activated Slag ◽  
Alkali Activated

Reduced graphene oxide (rGO) has been widely used to modify the mechanical performance of alkali activated slag composites (AASC); however, the mechanism is still unclear and the electrical properties of rGO reinforced AASC are unknown. Here, the rheological, mechanical, and electrical properties of the AASC containing rGO nanosheets (0, 0.1, 0.2, and 0.3 wt.%) are investigated. Results showed that rGO nanosheets addition can significantly improve the yield stress, plastic viscosity, thixotropy, and compressive strength of the AASC. The addition of 0.3 wt.% rGO nanosheets increased the stress, viscosity, thixotropy, and strength by 186.77 times, 3.68 times, 15.15 times, and 21.02%, respectively. As for electrical properties, the impedance of the AASC increased when the rGO content was less than 0.2 wt.% but decreased with the increasing dosage. In contrast, the dielectric constant and electrical conductivity of the AASC containing rGO nanosheets decreased and then increased, which can be attributed to the abundant interlayer water and the increasing structural defects as the storage sites for charge carriers, respectively. In addition, the effect of graphene oxide (GO) on the AASC is also studied and the results indicated that the agglomeration of GO nanosheets largely inhibited the application of it in the AASC, even with a small dosage.

scholarly journals Functionalized Reduced Graphene Oxide Thin Films for Ultrahigh CO2 Gas Sensing Performance at Room Temperature

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 623
Author(s):  
Monika Gupta ◽  
Huzein Fahmi Hawari ◽  
Pradeep Kumar ◽  
Zainal Arif Burhanudin ◽  
Nelson Tansu
Keyword(s):  
Thin Films ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Gas Sensor ◽  
Functional Groups ◽  
Recovery Time ◽  
Room Temperature ◽  
Co2 Gas ◽  
Reduced Graphene ◽  
Response And Recovery

The demand for carbon dioxide (CO2) gas detection is increasing nowadays. However, its fast detection at room temperature (RT) is a major challenge. Graphene is found to be the most promising sensing material for RT detection, owing to its high surface area and electrical conductivity. In this work, we report a highly edge functionalized chemically synthesized reduced graphene oxide (rGO) thin films to achieve fast sensing response for CO2 gas at room temperature. The high amount of edge functional groups is prominent for the sorption of CO2 molecules. Initially, rGO is synthesized by reduction of GO using ascorbic acid (AA) as a reducing agent. Three different concentrations of rGO are prepared using three AA concentrations (25, 50, and 100 mg) to optimize the material properties such as functional groups and conductivity. Thin films of three different AA reduced rGO suspensions (AArGO25, AArGO50, AArGO100) are developed and later analyzed using standard FTIR, XRD, Raman, XPS, TEM, SEM, and four-point probe measurement techniques. We find that the highest edge functionality is achieved by the AArGO25 sample with a conductivity of ~1389 S/cm. The functionalized AArGO25 gas sensor shows recordable high sensing properties (response and recovery time) with good repeatability for CO2 at room temperature at 500 ppm and 50 ppm. Short response and recovery time of ~26 s and ~10 s, respectively, are achieved for 500 ppm CO2 gas with the sensitivity of ~50 Hz/µg. We believe that a highly functionalized AArGO CO2 gas sensor could be applicable for enhanced oil recovery, industrial and domestic safety applications.

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