scholarly journals Investigation of chemical reduction of graphene oxide with many reduced agents

2015 ◽  
Vol 18 (2) ◽  
pp. 197-210
Author(s):  
Tam Thanh Mai ◽  
Nhan Thuc Chi Ha ◽  
Van Thi Thanh Khuat ◽  
Huy Thuc Ha
Keyword(s):  
Graphene Oxide ◽  
Graphite Oxide ◽  
Chemical Reduction ◽  
Graphene Film ◽  
Reduction Process ◽  
Reducing Agents ◽  
Reducing Agent ◽  
X Ray Diffraction ◽  
Analysis Methods ◽  
Reducing Ability

Graphene based on graphite oxide prepared by chemical reduction method is always interesting for scientists since the early days of discovery of graphene. Many different reducing agents are recommended, however every reducing agent is only active on one type of functional groups on the structure of graphene oxide. For studying clearly the reducing ability of the chemical reducing agent, this research has focused on investigating the possibility of 3 reducing agents such as N2H4, NaBH4 and HI. Besides, polyethylene oxide is also used as modified agent to completely exfoliate of graphite oxide before continuing the reduction process. Based on spectral analysis methods such as Fourier transform infrared (FTIR), UV-Vis and Raman spectroscopy, we have demonstrated the reduced ability of each agent, and strong reducing agent is HI. Exfoliated structure of MGO-PEG and graphene is demonstrated by means of X-ray diffraction analysis and scanning (SEM) and transmittance (TEM) electron microscopy. The thermal analysis methods such as TGA and DSC also contribute to clarify the role of each reducing agent. Finally, the four-probe method was used to determine the sheets resistance of the graphene film: RGO-HI (120 Ω/square), RGO-Na (1300 Ω/square) and RGO-Hz (1500 Ω/square). This study contributes to clarify the reducing ability of N2H4, NaBH4 and HI on the same kind of graphene oxide that has not yet been studied.

scholarly journals Study of Reduced Graphene Oxide Preparation by Hummers’ Method and Related Characterization

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Ning Cao ◽  
Yuan Zhang
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Graphite Oxide ◽  
Chemical Reduction ◽  
Raw Material ◽  
Flake Graphite ◽  
X Ray Diffraction ◽  
Hummers Method ◽  
Reduced Graphene ◽  
Potential Applications

As a novel two-dimensional carbon material, graphene has fine potential applications in the fields of electron transfer agent and supercapacitor material for its excellent electronic and optical property. However, the challenge is to synthesize graphene in a bulk quantity. In this paper, graphite oxide was prepared from natural flake graphite by Hummers’ method through liquid oxidization, and the reduced graphene oxide was obtained by chemical reduction of graphene oxide using NH3·H2O aqueous solution and hydrazine hydrate. The raw material graphite, graphite oxide, and reduced graphene oxide were characterized by X-ray diffraction (XRD), attenuated total reflectance-infrared spectroscopy (ATR-IR), and field emission scanning electron microscope (SEM). The results indicated that the distance spacing of graphite oxide was longer than that of graphite and the crystal structure of graphite was changed. The flake graphite was oxidized to graphite oxide and lots of oxygen-containing groups were found in the graphite oxide. In the morphologies of samples, fold structure was found on both the surface and the edge of reduced graphene oxide.

scholarly journals Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process—TEM, XRD, Raman, IR and Surface Electron Spectroscopic Studies

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5728
Author(s):  
Beata Lesiak ◽  
Grzegorz Trykowski ◽  
József Tóth ◽  
Stanisław Biniak ◽  
László Kövér ◽  
...  
Keyword(s):  
High Pressure ◽  
Graphene Oxide ◽  
Chemical Reduction ◽  
Reduction Process ◽  
Microwave Treatment ◽  
Spectroscopic Studies ◽  
Reducing Agent ◽  
Vacancy Defects ◽  
Microwave Reactor ◽  
Oxygen Groups

Reduced graphene oxide (rGO) was prepared by chemical reduction of graphene oxide (GO) (with a modified Hummers method) in aqueous solutions of hydrazine (N2H4), formaldehyde (CH2O), formic acid (HCO2H) accompanied by a microwave treatment at 250 °C (MWT) by a high pressure microwave reactor (HPMWR) at 55 bar. The substrates and received products were investigated by TEM, XRD, Raman and IR spectroscopies, XPS, XAES and REELS. MWT assisted reduction using different agents resulted in rGOs of a large number of vacancy defects, smaller than at GO surface C sp3 defects, oxygen groups and interstitial water, interlayer distance and diameter of stacking nanostructures (flakes). The average number of flake layers obtained from XRD and REELS was consistent, being the smallest for CH2O and then increasing for HCO2H and N2H4. The number of layers in rGOs increases with decreasing content of vacancy, C sp3 defects, oxygen groups, water and flake diameter. MWT conditions facilitate formation of vacancies and additional hydroxyl, carbonyl and carboxyl groups at these vacancies, provide no remarkable modification of flake diameter, what results in more competitive penetration of reducing agent between the interstitial sites than via vacancies. MWT reduction of GO using a weak reducing agent (CH2O) provided rGO of 8 layers thickness.

Efficient reduction of graphene oxide nanosheets using Na2C2O4 as a reducing agent

2015 ◽  
Vol 08 (02) ◽  
pp. 1550026 ◽  
Author(s):  
Mohamad Fahrul Radzi Hanifah ◽  
Juhana Jaafar ◽  
Madzlan Aziz ◽  
A. F. Ismail ◽  
M. H. D. Othman ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Chemical Reduction ◽  
Single Layer ◽  
Reduction Process ◽  
Atomic Ratio ◽  
Reducing Agent ◽  
Sodium Oxalate ◽  
Transmission Electron ◽  
Efficient Reduction

The efficient synthesis of reduced graphene oxide (RGO) nanosheets via chemical reduction process of exfoliated graphene oxide (GO) nanosheets was performed by introducing sodium oxalate ( Na 2 C 2 O 4) as a reducing agent. To study the effects of the reduction time on the synthesized RGO, the GO was reduced within -1/2, 1 and 2 h for RGO-1, RGO-2 and RGO-3, respectively. The C/O atomic ratio of the synthesized RGO-3 has increased from 2.16 to 6.32 after reduction as determined by X-ray photoelectron spectroscopy (XPS). The morphology analysis of the RGO-3 was determined by high-resolution transmission electron microscopy (HRTEM) almost revealed the formation of single layer. The number of RGO layers decreases as the time of the reduction increases. Based on these analysis results, sodium oxalate plays an important role in the efficient removal of the oxygen containing groups in the GO to produce high quality of RGO.

scholarly journals Synthesis and Characterization of Graphene Thin Films by Chemical Reduction of Exfoliated and Intercalated Graphite Oxide

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
F. T. Thema ◽  
M. J. Moloto ◽  
E. D. Dikio ◽  
N. N. Nyangiwe ◽  
L. Kotsedi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Chemical Reduction ◽  
Reduction Process ◽  
Colloidal Dispersion ◽  
Functionalized Graphene ◽  
X Ray Diffraction ◽  
Functionalized Graphene Oxide ◽  
Force Microscopy ◽  
Atomic Force ◽  
Polar Aprotic Solvent

Commercial flakes of graphite were prepared into functionalized graphene oxide (GO) by chemical treatment. After the exfoliation and intercalation of graphene into functionalized graphene oxide that formed stable colloidal dispersion in polar aprotic solvent, the reduction process was undertaken by continuous stirring with hydrazine hydrate. The reduced material was characterized by X-ray diffraction (XRD), attenuated total reflectance (ATR) FT-IR, ultraviolet visible (UV-vis), atomic force microscopy (AFM) and Raman spectroscopy which confirm the oxidation of graphite and reduction of graphene oxide into graphene sheet.

Green Reduction of Graphene Oxide Coated Polyamide Fabric Using Carob Extract

2020 ◽  
Vol 7 (6) ◽  
pp. 33-40
Author(s):  
Nergis Gültekin ◽  
İsmail Usta ◽  
Bahattin Yalçin
Keyword(s):  
Graphene Oxide ◽  
Chemical Reduction ◽  
Reduction Process ◽  
Dip Coating ◽  
X Ray Diffraction ◽  
Reduced Graphene ◽  
Structure Morphology ◽  
Coating Method ◽  
Polyamide Fabric ◽  
Dip Coating Method

A green reduction processes for graphene oxide using carob extract is reported in this work. In this study, graphene oxide (GO) nanosheets were synthesized using the improved Hummer's method and applied to polyamide fabric thorough the simple dip coating method. Then, the graphene oxide was reduced with a chemical reduction process using carob extract as a green reducing agent to give the reduced graphene oxide (RGO) material. The reduction time was studied. The structure, morphology, and thermal behavior of the material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), respectively. The electrical resistivity results clearly revealed that the GO coated polyamide fabric was successfully converted to the RGO coated polyamide fabric with the effective elimination of oxygen containing functional groups.

scholarly journals Low Surface Roughness Graphene Oxide Film Reduced with Aluminum Film Deposited by Magnetron Sputtering

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1428
Author(s):  
Xiaowei Fan ◽  
Xuguo Huai ◽  
Jie Wang ◽  
Li-Chao Jing ◽  
Tao Wang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Electron Transfer ◽  
Graphene Oxide ◽  
Magnetron Sputtering ◽  
Chemical Reduction ◽  
Graphene Film ◽  
Conductivity Measurement ◽  
Electrical Conductivity Measurement ◽  
Vis Spectroscopy ◽  
Hcl Solution

Graphene film has wide applications in optoelectronic and photovoltaic devices. A novel and facile method was reported for the reduction of graphene oxide (GO) film by electron transfer and nascent hydrogen produced between aluminum (Al) film deposited by magnetron sputtering and hydrochloric acid (HCl) solution for only 5 min, significantly shorter than by other chemical reduction methods. The thickness of Al film was controlled utilizing a metal detection sensor. The effect of the thickness of Al film and the concentration of HCl solution during the reduction was explored. The optimal thickness of Al film was obtained by UV-Vis spectroscopy and electrical conductivity measurement of reduced GO film. Atomic force microscope images could show the continuous film clearly, which resulted from the overlap of GO flakes, the film had a relatively flat surface morphology, and the surface roughness reduced from 7.68 to 3.13 nm after the Al reduction. The film sheet resistance can be obviously reduced, and it reached 9.38 kΩ/sq with a high transmittance of 80% (at 550 nm). The mechanism of the GO film reduction by electron transfer and nascent hydrogen during the procedure was also proposed and analyzed.

scholarly journals Magnetization of Ultraviolet-Reduced Graphene Oxide Flakes in Composites Based on Polystyrene

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2519
Author(s):  
Alexander N. Ionov ◽  
Mikhail P. Volkov ◽  
Marianna N. Nikolaeva ◽  
Ruslan Y. Smyslov ◽  
Alexander N. Bugrov
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Reduction Process ◽  
X Ray Diffraction ◽  
Mesoscopic Structure ◽  
Reduced Graphene ◽  
Study Results ◽  
Edge Defects ◽  
Mesoscopic Level ◽  
Ferromagnetic Hysteresis

This work presents our study results of the magnetization of multilayer UV-reduced graphene oxide (UV-rGO), polymer matrix (polystyrene), and a conjugated composite based on them. The mesoscopic structure of the composites synthesized in this work was studied by such methods as X-ray diffraction, SEM, as well as NMR-, IR- and Raman spectroscopy. The magnetization of the composites under investigation and their components was measured using a vibrating-sample magnetometer. It has been shown that the UV-reduction process leads to the formation of many submicron holes distributed inside rGO flakes, which can create edge defects, causing possibly magnetic order in the graphite samples under investigation on the mesoscopic level. This article provides an alternative explanation for the ferromagnetic hysteresis loop in UV-rGO on the base of superconductivity type-II.

scholarly journals Size Control of Synthesized Silver Nanoparticles by Simultaneous Chemical Reduction and Laser Fragmentation in Origanum majorana Extract: Antibacterial Application

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2326
Author(s):  
Entesar Ali Ganash ◽  
Reem Mohammad Altuwirqi
Keyword(s):  
Silver Nanoparticles ◽  
Irradiation Time ◽  
Chemical Reduction ◽  
Size Control ◽  
Reduction Process ◽  
Laser Wavelength ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Transmission Electron ◽  
Origanum Majorana

In this work, silver nanoparticles (Ag NPs) were synthesized using a chemical reduction approach and a pulsed laser fragmentation in liquid (PLFL) technique, simultaneously. A laser wavelength of 532 nm was focused on the as produced Ag NPs, suspended in an Origanum majorana extract solution, with the aim of controlling their size. The effect of liquid medium concentration and irradiation time on the properties of the fabricated NPs was studied. While the X-ray diffraction (XRD) pattern confirmed the existence of Ag NPs, the UV–Vis spectrophotometry showed a significant absorption peak at about 420 nm, which is attributed to the characteristic surface plasmon resonance (SPR) peak of the obtained Ag NPs. By increasing the irradiation time and the Origanum majora extract concentration, the SPR peak shifted toward a shorter wavelength. This shift indicates a reduction in the NPs’ size. The effect of PLFL on size reduction was clearly revealed from the transmission electron microscopy images. The PLFL technique, depending on experimental parameters, reduced the size of the obtained Ag NPs to less than 10 nm. The mean zeta potential of the fabricated Ag NPs was found to be greater than −30 mV, signifying their stability. The Ag NPs were also found to effectively inhibit bacterial activity. The PLFL technique has proved to be a powerful method for controlling the size of NPs when it is simultaneously associated with a chemical reduction process.

scholarly journals Green Synthesis of Novel Jasmine Bud-Shaped Copper Nanoparticles

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Malathi Sampath ◽  
Ramya Vijayan ◽  
Ezhilarasu Tamilarasu ◽  
Abiraman Tamilselvan ◽  
Balasubramanian Sengottuvelan
Keyword(s):  
Copper Nanoparticles ◽  
Isonicotinic Acid ◽  
Chemical Reduction ◽  
Average Particle Size ◽  
Acid Hydrazide ◽  
Reducing Agent ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Atomic Force ◽  
Transmission Electron

Novel jasmine bud-shaped copper nanoparticles were synthesized by a green chemical reduction method using polyvinylpyrrolidone (PVP) as a capping agent, L-ascorbic acid (AA) as a reducing agent as well as antioxidant agent, isonicotinic acid hydrazide (INH) as a reducing agent, and water as a solvent at 60–70°C (pH-7) in the presence of air. The UV-Vis absorption maximum obtained is 573 nm. The crystal lattice (fcc) structure of Cu Nps was confirmed by X-ray diffraction (XRD). The novel jasmine bud shape was visualized in a transmission electron microscope (TEM). The height of single copper nanobud was 6.41 nm as measured by atomic force microscope (AFM). The average particle size 6.95 nm is obtained by XRD results. Antibacterial activity of the Cu nanobuds was evaluated by testing against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria.

Shape-Controlled Synthesis and Formation Mechanism of Cobalt Nanopowders by a PVP-Assisted Method

2010 ◽  
Vol 654-656 ◽  
pp. 1186-1189 ◽  
Author(s):  
Bing Cong Zhang ◽  
Hong Ying Yu ◽  
Dong Bai Sun
Keyword(s):  
Hydrazine Hydrate ◽  
Chemical Reduction ◽  
Reducing Agent ◽  
Soft Template ◽  
Basic Solution ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Nucleation Sites ◽  
Shape Controlled

Three different kinds of morphologies including spherical, chainlike and wirelike cobalt nanopowders, have been synthesized by chemical reduction of coblat chloride solution with hydrazine hydrate in basic solution. The products were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). It was revealed that the morphologies of the nanopowders depend on the concentration of Co2+ and the way of adding reducing agent (hydrazine hydrate). These two features affected the nucleation sites and the number of nucleuses. When the concentration of Co2+ was low, nucleuses formed in the soft template, while the reducing of the reducing agent added drop wise, a little number of nucleuses was formed. Based on that, a mechanism of formation, as a basis of gram-scale syntheses, was proposed.

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