scholarly journals Chemical and structural properties of reduced graphene oxide—dependence on the reducing agent

2020 ◽  
Vol 56 (5) ◽  
pp. 3738-3754
Author(s):  
B. Lesiak ◽  
G. Trykowski ◽  
J. Tóth ◽  
S. Biniak ◽  
L. Kövér ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Sodium Borohydride ◽  
Reduction Rate ◽  
Graphite Powder ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Vacancy Defects ◽  
Group Reduction ◽  
Reduced Graphene

AbstractGraphene oxide (GO) prepared from graphite powder using a modified Hummers method and reduced graphene oxide (rGO) obtained from GO using different reductants, i.e., sodium borohydride, hydrazine, formaldehyde, sodium hydroxide and L-ascorbic acid, were investigated using transmission electron microscopy, X-ray diffraction, Raman, infrared and electron spectroscopic methods. The GO and rGOs’ stacking nanostructure (flake) size (height x diameter), interlayer distance, average number of layers, distance between defects, elementary composition, content of oxygen groups, C sp3 and vacancy defects were determined. Different reductants applied to GO led to modification of carbon to oxygen ratio, carbon lattice (vacancy) and C sp3 defects with various in-depth distribution of C sp3 due to oxygen group reduction proceeding as competing processes at different rates between interstitial layers and in planes. The reduction using sodium borohydride and hydrazine in contrary to other reductants results in a larger content of vacancy defects than in GO. The thinnest flakes rGO obtained using sodium borohydride reductant exhibits the largest content of vacancy, C sp3 defects and hydroxyl group accompanied by the smallest content of epoxy, carboxyl and carbonyl groups due to a mechanism of carbonyl and carboxyl group reduction to hydroxyl groups. This rGO similar diameter to GO seems to result from a predominant reduction rate between the interstitial layers. The thicker flakes of a smaller diameter than in GO are obtained in rGOs prepared using remaining reductants and result from a higher rate of reduction of in plane defects.

scholarly journals Synthesis and Characterization of Reduced Graphene Oxide (rGO) Started from Graphene Oxide (GO) Using the Tour Method with Different Parameters

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Adere Tarekegne Habte ◽  
Delele Worku Ayele
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Potassium Permanganate ◽  
Chemical Reduction ◽  
Volume Ratio ◽  
Graphite Powder ◽  
Green Approach ◽  
Synthesis Strategy ◽  
Reduced Graphene ◽  
Diffraction Patterns

A new approach to synthesize graphene is oxidizing graphite powder with a mixture of H2SO4/H3PO4 acids and potassium permanganate. Parameters such as reaction time, reaction temperature, and amount of concentration were varied to study the degree of oxidation of graphite to graphene oxide. Currently, an improved method for the preparation of graphene oxide was the most common one. A mixture of H2SO4/H3PO4 (9 : 1 volume ratio) instead of only H2SO4 resulted in increased hydrophilic and oxidized GO without the emission of toxic gas, which differs from the traditional Hummers’ method. The graphene oxide (GO) was converted to reduced graphene oxide (rGO) by chemical reduction using ascorbic acid as the reducing agent. The GO and rGO were characterized by UV-visible spectroscopy, FTIR spectroscopy, and X-ray diffraction patterns. The result showed that treating graphite powder with potassium permanganate (1 : 9) and a mixture of concentrated H2SO4/H3PO4 acids at 50°C for 12 hours resulted in a better oxidation degree. The designed synthesis strategy could be easily controlled and is an alternative green approach for the production of graphene oxide and reduced graphene oxide.

Wrinkled reduced graphene oxide nanosheets for highly sensitive and easy recoverable NH3 gas detector

RSC Advances ◽  
2014 ◽  
Vol 4 (87) ◽  
pp. 46930-46933 ◽  
Author(s):  
Su Zhang ◽  
Di Zhang ◽  
Vitaly I. Sysoev ◽  
Olga V. Sedelnikova ◽  
Igor P. Asanov ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
High Sensitivity ◽  
Graphite Powder ◽  
Gas Detection ◽  
Graphene Oxide Nanosheets ◽  
Chemical Exfoliation ◽  
Reduced Graphene ◽  
Highly Sensitive ◽  
Gas Detector

Highly wrinkled reduced graphene oxide nanosheets were prepared by chemical exfoliation of ball-milled graphite powder. This material showed high sensitivity and simple recovery ability for NH3 gas detection.

VOCs Sensing Property of Graphene Oxide Thin Film by Reduction Rate

2013 ◽  
Vol 440 ◽  
pp. 64-68 ◽  
Author(s):  
Ho Sang Ahn ◽  
Hye Jin Park ◽  
Ju Hyun Oh ◽  
Jin Chul Joo ◽  
Dong Joo Kim
Keyword(s):  
Thin Film ◽  
Graphene Oxide ◽  
Thermal Treatment ◽  
Reduced Graphene Oxide ◽  
Gas Sensing ◽  
Reduction Rate ◽  
Oxide Thin Film ◽  
Film Sensor ◽  
Reduced Graphene ◽  
Different Temperatures

We demonstrate a combinatorial graphene oxide (GO) and reduced graphene oxide (rGO) thin film sensor fabricated by spin coating and dip casting method. Thermal treatment was followed to convert graphene oxide into reduced graphene oxide at different temperatures. 100ppm of evaporated methanol was utilized to examine the resistance profile of graphene oxide thin film and reduced graphene oxide thin film. Crystalline phase of GO and rGO were characterized by XRD. Surface roughness was observed by FE-SEM. Obvious opposite sensing property of GO and rGO were observed according to drying conditions.It was attributed to the change in number of radicals and type attached to the edge and surface of graphene oxide during reduction. Authors suggest that control of reduction rate by thermal treatment would be the one of the readiest approaches to enhance the selectivity of gas sensing in terms of direction of reaction.

Synthesis and Characterization of Zinc Oxide-Reduced Graphene Oxide Hybrid Materials and their Application for Nitrogen Dioxide Detection

2020 ◽  
Vol 302 ◽  
pp. 45-50
Author(s):  
Worawut Muangrat ◽  
Thanawee Chodjarusawad ◽  
Akapong Suwattanamala ◽  
Chaisak Issro
Keyword(s):  
Electron Microscopy ◽  
Zinc Oxide ◽  
Graphene Oxide ◽  
Nitrogen Dioxide ◽  
Reduced Graphene Oxide ◽  
Hybrid Materials ◽  
Graphite Powder ◽  
Ethanol Solution ◽  
Step Method ◽  
Reduced Graphene

Herein, we report a facile synthesis of zinc oxide-reduced graphene oxide (ZnO-rGO) hybrid materials by two-step method. Firstly, rGO was synthesized by using graphite powder mixed with sodium nitrate, sulfuric acid and potassium permanganate via Hummers method. Synthesized rGO were dispersed in ethanol by ultra-sonication for a designated time period. Then, zinc oxide (ZnO) powder was added into rGO-ethanol solution and transferred into Teflon-lined stainless steel autoclave. The ZnO-rGO was produced by hydrothermal method at 180 °C for 120 and 180 min (here after referred to as ZnO(120)-rGO and ZnO(180)-rGO, respectively). The morphological and crystalline structures of synthesized rGO and ZnO-rGO were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Synthesized ZnO-rGO was exposed to 100 parts per million (ppm) nitrogen dioxide (NO2) gas at room temperature, 50 °C and 75 °C for testing its sensing performance. The results show that ZnO(180)-rGO hybrid materials exhibit high response to NO2 gas at 50 °C and 75 °C. The electrical resistance of ZnO-rGO sensors decreased when the sensors responded to NO2 gas, indicating a p-type behavior. Moreover, the ZnO-rGO hybrid materials can detect 100 ppm NO2 gas with an operating temperature limit at 50 °C. The results imply that synthesized ZnO-rGO hybrid materials could be used as gas sensing device for ppm-level NO2 detection at low temperature and consume low power.

scholarly journals Gum Kondagogu/Reduced Graphene Oxide Framed Platinum Nanoparticles and Their Catalytic Role

Molecules ◽  
2019 ◽  
Vol 24 (20) ◽  
pp. 3643 ◽  
Author(s):  
Venkateshaiah ◽  
Silvestri ◽  
Ramakrishnan ◽  
Wacławek ◽  
Padil ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Platinum Nanoparticles ◽  
Environmentally Benign ◽  
Hydroxyl Groups ◽  
Average Particle ◽  
Face Centered Cubic ◽  
Reduced Graphene ◽  
Gum Kondagogu

This study investigates an environmentally benign approach to generate platinum nanoparticles (Pt NP) supported on the reduced graphene oxide (RGO) by non-edible gum waste of gum kondagogu (GK). The reaction adheres to the green chemistry approach by using an aqueous medium and a nontoxic natural reductant—GK—whose abundant hydroxyl groups facilitate in the reduction process of platinum salt and helps as well in the homogenous distribution of ensued Pt NP on RGO sheets. Scanning Electron Microscopy (SEM) confirmed the formation of kondagogu gum/reduced graphene oxide framed spherical platinum nanoparticles (RGO-Pt) with an average particle size of 3.3 ± 0.6 nm, as affirmed by Transmission Electron Microscopy (TEM). X-ray Diffraction (XRD) results indicated that the Pt NPs formed are crystalline with a face-centered cubic structure, while morphological analysis by XRD and Raman spectroscopy revealed a simultaneous reduction of GO and Pt. The hydrogenation of 4-nitrophenol could be accomplished in the superior catalytic performance of RGO-Pt. The current strategy emphasizes a simple, fast and environmentally benign technique to generate low-cost gum waste supported nanoparticles with a commendable catalytic activity that can be exploited in environmental applications.

scholarly journals Preparation and Characterization of Reduced Graphene Oxide Sheets via Water-Based Exfoliation and Reduction Methods

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Vorrada Loryuenyong ◽  
Krit Totepvimarn ◽  
Passakorn Eimburanapravat ◽  
Wanchai Boonchompoo ◽  
Achanai Buasri
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Graphite Oxide ◽  
Low Cost ◽  
Graphite Powder ◽  
Chemical Oxidation ◽  
Distilled Water ◽  
Manufacturing Method ◽  
Ultrasound Frequency ◽  
Reduced Graphene

This research studied the synthesis of graphene oxide and graphene via a low-cost manufacturing method. The process started with the chemical oxidation of commercial graphite powder into graphite oxide by modified Hummer’s method, followed by the exfoliation of graphite oxide in distilled water using the ultrasound frequency from a laboratory ultrasonic bath. Finally, the oxygen functional groups on exfoliated graphite oxide or graphene oxide were eliminated by stirring in hot distilled water at 95°C, as a replacement for highly toxic and dangerously unstable hydrazine. The results assured that stirring in hot distilled water could give the product of graphene or reduced graphene oxide. The samples were characterized by FTIR, XRD, TGA, Raman spectroscopy, SEM, and TEM methods.

Chlorine-functionalized reduced graphene oxide for methylene blue removal

RSC Advances ◽  
2015 ◽  
Vol 5 (65) ◽  
pp. 52466-52472 ◽  
Author(s):  
Chubei Wang ◽  
Jianwei Zhou ◽  
Liangliang Chu
Keyword(s):  
Methylene Blue ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Mild Condition ◽  
Sulfuryl Chloride ◽  
Hydroxyl Group ◽  
Reduced Graphene ◽  
Methylene Blue Removal

Hydroxyl group in graphene oxide can be substituted by chlorine in sulfuryl chloride at mild condition.

scholarly journals Performances of Reduced Graphene Oxide/Iron (III) Oxide/Silica Dioxide (rGO/Fe3O4/SiO2) as a Potential Oxygen Reduction Electrocatalyst in Fuel Cell

2021 ◽  
Vol 50 (7) ◽  
pp. 2017-2024
Author(s):  
Farhanini Yusoff ◽  
Karthi Suresh
Keyword(s):  
Graphene Oxide ◽  
Oxygen Reduction ◽  
Reduced Graphene Oxide ◽  
Modified Electrode ◽  
Electrochemical Analysis ◽  
Hydroxyl Group ◽  
Current Response ◽  
Reduced Graphene ◽  
Bet Analysis ◽  
Silica Dioxide

Synthesis of the nanocomposite comprises reduced graphene oxide, iron (III) oxide and silica dioxide nanocomposites which were denoted as rGO/Fe3O4/SiO2. The acquired nanocomposite was determined to be a substitute for platinum electrode in oxygen reduction reaction (ORR) to catalyze reaction, as usage of platinum causes disadvantages in production. The nanocomposite was analyzed physically and electrochemically to ensure the quality of the synthesized compound. Fourier transform-infrared spectroscopy (FTIR) shows the presences of functional groups such as O-H hydroxyl group, C=C, C=O and existence of silica peak in the spectra of rGO/Fe3O4/SiO2, where the data is also supported by SEM-EDS. Raman Spectrophotometer shows the structural change of three different graphene related materials as modification took place and X-Ray Diffraction (XRD) analysis confirms the reduction of GO into rGO, where the crystalline structure decreased significantly approximately about 10 nm. This data supported with Brunauer-Emmett-Teller (BET) analysis through surface area examination. The compound of rGO/Fe3O4/SiO2 was drop-casted onto glassy carbon electrode (GCE) for modification into rGO/Fe3O4/SiO2/GCE to carry out electrochemical analysis where Cyclic Voltammetry (CV) shows current response by modified electrode is greater than bare GCE while Electron Impedance Spectroscopy (EIS) of same modified electrode affirms the sample underwent reversible process with stable and rapid electron transfers with minimal resistance charge transfer (RCT). The study of ORR was carried out and observed a good electrochemical response of the nanocomposite when purged with oxygen gas.

Functionalization and Chemical Linking of Reduced Graphene Oxide or Graphite onto Polyurethane and the Impact on the Tensile Strength and Sheet Resistance of Polymer Composites

2018 ◽  
Vol 26 (2) ◽  
pp. 141-153
Author(s):  
Yong-Chan Chung ◽  
Ho-Sung Kim ◽  
Byoung Chul Chun
Keyword(s):  
Tensile Strength ◽  
Graphene Oxide ◽  
Shape Memory ◽  
Reduced Graphene Oxide ◽  
Sheet Resistance ◽  
Sharp Decrease ◽  
Hydroxyl Groups ◽  
Functionalized Graphene Oxide ◽  
Reduced Graphene ◽  
The Impact

Reduced graphene oxide (RGO) or graphite is functionalized with hydroxyl groups for linking to the sides of polyurethane (PU) chains. Blended PU with RGO or graphite is prepared as a control for comparison. The PU composites are compared with respect to their spectroscopic, thermal, mechanical, shape memory, and sheet resistance properties. Scanning electron microscopy images demonstrate the good distribution of functionalized graphene oxide (FGO) or functionalized graphite (FG) particles on the inner surface of the PU. The linking of FGO or FG onto PU does not significantly affect the thermal behavior or shape memory properties but sharply improves the tensile strength of the PU composites without a noticeable decrease in tensile strain. The shape recovery of PU composites remains at approximately 90%, regardless of the FGO or FG content. The FG-linked PU composites exhibit a sharp decrease in sheet resistance as the FG content increases, whereas the sheet resistance of the FGO-linked PU composites does not decrease with increasing FGO content. The control PU composites with blended RGO or graphite show significant reductions in their sheet resistance. Considering the ease of functionalization of the graphite surface and the significant improvement in tensile strength, linking FG onto PU is advantageous for the development of PU composites with low sheet resistance.

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