scholarly journals Reduction of Graphene Oxide: Controlled Synthesis by Microwave Irradiation

Molekul ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 56
Author(s):  
Endah Fitriani Rahayu ◽  
Bunnari Bunnari ◽  
Andri Hardyansyah
Keyword(s):  
Graphene Oxide ◽  
Microwave Irradiation ◽  
Reduction Process ◽  
Controlled Synthesis ◽  
Microwave Exposure ◽  
Graphite Oxidation ◽  
Reduced Graphene ◽  
Infra Red ◽  
The Fourier Transform ◽  
Modified Hummers Method

Graphene has been attracting enormous attention in the scientific community because of its unique properties and use for various applications. Graphene has been synthesized in various ways, one of which is the graphite oxidation method to form graphene oxide (GO). Reduction of GO to reduced graphene oxide (RGO) is necessary to recover the conjugated network and electrical conductivity, and for this research, this was achieved using microwave irradiation. Microwave synthesis provides an alternative method, saving more time in the reaction process. In this research, graphene was synthesized from graphite by the modified Hummers method and microwave irradiation. This research proves that graphene can be synthesized with a high-quality structure and in a shorter amount of time using microwave irradiation to reduce GO. With longer microwave exposure, less GO is present in the sample, as indicated by the absence of an n–π* electronic transition in the absorbance graph and the absence of oxide groups in the Fourier-Transform Infra-Red spectrum. With increasing microwave power, the reduction process is short-lived, and better quality RGO is produced. This study shows that the new reduction process occurs within 20 minutes with a power of 450 and 630 watts, but at 900 watts, the reduction of GO occurs within 10 minutes, as shown by UV-Vis and FTIR spectra.

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.

Chemically reduced graphene oxide-coated knitted fabric imparted conductivity and outstanding hydrophobicity

2021 ◽  
pp. 004051752199547
Author(s):  
Min Hou ◽  
Xinghua Hong ◽  
Yanjun Tang ◽  
Zimin Jin ◽  
Chengyan Zhu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Chemical Reduction ◽  
Knitted Fabric ◽  
Mesh Structure ◽  
Reduced Graphene ◽  
Chemically Reduced Graphene Oxide ◽  
Modified Hummers Method

Functionalized knitted fabric, as a kind of flexible, wearable, and waterproof material capable of conductivity, sensitivity and outstanding hydrophobicity, is valuable for multi-field applications. Herein, the reduced graphene oxide (RGO)-coated knitted fabric (polyester/spandex blended) is prepared, which involves the use of graphite oxide (GO) by modified Hummers method and in-situ chemical reduction with hydrazine hydrate. The treated fabric exhibits a high electrical conductivity (202.09 S/cm) and an outstanding hydrophobicity (140°). The outstanding hydrophobicity is associated with the morphology of the fabric and fiber with reference to pseudo-infiltration. These properties can withstand repeated bending and washing without serious deterioration, maintaining good electrical conductivity (35.70 S/cm) and contact angle (119.39°) after eight standard washing cycles. The material, which has RGO architecture and continuous loop mesh structure, can find wide use in smart garment applications.

Synthesis and Study of Reduced Graphene Oxide layers under Microwave Irradiation

2018 ◽  
Vol 5 (2) ◽  
pp. 3403-3410 ◽  
Author(s):  
D. Sreedhar ◽  
Sandhya Devireddy ◽  
Vasudeva Rao Veeredhi
Keyword(s):  
Graphene Oxide ◽  
Microwave Irradiation ◽  
Reduced Graphene Oxide ◽  
Oxide Layers ◽  
Reduced Graphene

Optical Characteristics of Multilayer Reduced Graphene Oxides Films Fabricated Using UV Oven Spraying Technique with Various Interval Irradiation Time

2021 ◽  
Vol 1028 ◽  
pp. 279-284
Author(s):  
Nur Khanifah ◽  
Diyan Unmu Dzujah ◽  
Vika Marcelina ◽  
Rahmat Hidayat ◽  
Fitrilawati ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Irradiation Time ◽  
Active Material ◽  
Reduction Process ◽  
Optical Characteristics ◽  
Graphene Oxides ◽  
Super Capacitor ◽  
Reduced Graphene ◽  
Vis Spectroscopy ◽  
Coating Method

Reduced graphene oxide (RGO) is promising candidate to be used as an active material of super capacitor electrodes. Graphene oxide (GO) is mostly used as a precursor, therefore it is needed to remove its oxygen containing functional groups. Generally, the RGO films are obtained from Graphene Oxide (GO) films which are then treated using thermal reduction or photo reduction process. We developed a spraying coating method that called as UV oven spraying by combining spraying coating method and photo reduction process. By this deposition method, we can obtain RGO films directly from the GO precursor since deposition and photo reduction steps are taken place at the same time. Level of oxygen removal of the obtained RGO film depends on irradiation intensity and length of irradiation. In this work, we report the effect of varied length of irradiation time on the RGO optical characteristics. We prepared multilayer of RGO films using UV oven spraying technique on quartz substrates from 0.5 mg/ml commercial GO dispersion (Graphenea) with varied the UV irradiation time. We used 125-Watt mercury lamp that was set at distance of 30 cm from substrates. We examined the effect of varied of length of irradiation time on its optical characteristics using UV-Vis Spectroscopy. Level of reduction by provided irradiation time was examined using SEM/EDS measurement.

Nanohybrids of RGO nanosheets and 2-dimensional porous Co3O4 nanoflakes working as highly efficient counter electrodes for dye-sensitized solar cells

2016 ◽  
Vol 4 (43) ◽  
pp. 10323-10328 ◽  
Author(s):  
Feng Du ◽  
Xueqin Zuo ◽  
Qun Yang ◽  
Guang Li ◽  
Zongling Ding ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Solar Cells ◽  
Dye Sensitized Solar Cells ◽  
Reduction Process ◽  
Graphene Oxide Nanosheets ◽  
Counter Electrodes ◽  
Dye Sensitized ◽  
Reduced Graphene ◽  
Sensitized Solar Cells ◽  
Hydrothermal Reduction

In this paper, nanohybrids (Co3O4@RGO) of 2-dimensional (2D) porous Co3O4 nanoflakes anchored on reduced graphene oxide nanosheets have been fabricated by a facile hydrothermal reduction process.

Rapid Nucleation of Reduced Graphene Oxide-Supported Palladium Electrocatalysts for Methanol Oxidation Reaction

2019 ◽  
Vol 19 (11) ◽  
pp. 7236-7243
Author(s):  
Jen Chao Ng ◽  
Chou Yong Tan ◽  
Boon Hoong Ong ◽  
Atsunori Matsuda ◽  
Wan Jefrey Basirun ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Microwave Irradiation ◽  
Reduced Graphene Oxide ◽  
Oxidation Reaction ◽  
Room Temperature ◽  
Methanol Oxidation Reaction ◽  
Ph Adjustment ◽  
Reduced Graphene ◽  
High Supersaturation ◽  
Supported Palladium

Small sized electrocatalysts, which can be obtained by rapid nucleation and high supersaturation are imperative for outstanding methanol oxidation reaction (MOR). Conventional microwave synthesis processes of electrocatalysts include ultrasonication, stirring, pH adjustment, and microwave irradiation of the precursor mixture. Ethylene glycol (EG), which serves as a reductant and solvent was added during the ultrasonication or stirring stage. However, this step and pH adjustment resulted in unintended multi-stage gradual nucleation. In this study, the microwave reduction approach was used to induce rapid nucleation and high supersaturation in order to fabricate small-sized reduced graphene oxide-supported palladium (Pd/rGO) electrocatalysts via the delayed addition of EG, elimination of the pH adjustment step, addition of sodium carbonate (Na2CO3), prior microwave irradiation of the EG mixed with Na2CO3, and addition of room temperature precursor mixture. Besides its role as a second reducing agent, the addition of Na2CO3 was primarily intended to generate an alkaline condition, which is essential for the high-performance of electrocatalysts. Moreover, the microwave irradiation of the EG and Na2CO3 mixture generated highly reactive free radicals that facilitate rapid nucleation. Meanwhile, the room temperature precursor mixture increased supersaturation. Results showed improved electrochemically active surface area (78.97 m2 g−1, 23.79% larger), MOR (434.49 mA mg−1, 37.96% higher) and stability.

The Addition of Reduced Graphene Oxide Layer to TiO2 Photoanode of DSSC Using UV Oven Spraying Method

2020 ◽  
Vol 860 ◽  
pp. 15-21
Author(s):  
Lusi Safriani ◽  
Annisa Aprilia ◽  
Sri Suryaningsih ◽  
Fitri Yuliasari ◽  
Muhammad Rizki Nurawan ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Short Circuit ◽  
Dye Sensitized Solar Cells ◽  
Reduction Process ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Reduced Graphene ◽  
Sensitized Solar Cells ◽  
Spraying Method

The third generation of photovoltaic, called as dye-sensitized solar cells (DSSC) have attracted much attention and currently become an interesting research topics. One important part of DSSC that determines its performance is photoanodes. Recently, graphene has been used to enhance the efficiency of DSSC through the increasing of electronic transportation. Introduction of graphene into DSSC is realized by changing the form of graphene oxide (GO) into reduced graphene oxide (rGO) through the reduction process. In this work, DSSC based on TiO2 photoanodes modified by rGO were fabricated. rGO layer was deposited on TiO2 mesoporous layer using UV-oven spraying method. We found that parameters of DSSC such as open circuit voltage, short circuit current and fill factor increase with the incorporation of rGO layer in TiO2photoanodes. DSSC with TiO2/rGO photoanodes has the highest power conversion efficiency of 11.01% which contributed from the enhancement of short circuit current. The rGO layer found to be an effective layer to block charge recombination in photoanode.

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