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[Lecture Notes in Electrical Engineering] Engineering Vibration, Communication and Information Processing Volume 478 (ICoEVCI 2018, India) || A Facile Synthesis of Graphene Oxide (GO) and Reduced Graphene Oxide (RGO) by Electrochemical Exfoliation of Battery Electrode
摘要： Graphene is a two-dimensional allotrope of carbon, in which carbon atoms are arranged in a hexagonal structure. All carbon atoms in graphene are sp2 hybridized due to which three atoms are bonded to neighboring atoms and one electron is unbounded. Here, we have demonstrated a facile and low-cost technique to synthesize the graphene oxide and reduced graphene oxide from readily available battery graphite by means of an electrochemical method using liquid electrolyte. The graphite in the battery electrode has been expanded using acid for effective exfoliation. This is used to increase the interlayer spacing of graphite causes the van der Waals forces to cease. Graphene oxide and reduced graphene oxide (reduction using ascorbic acid) have been synthesized using this technique. The optical microscope image has shown few layer ?akes and X-ray powder diffraction (XRD) demonstrated the reduction of oxygen content. The proposed setup is cheap and environmentally benign in nature.
关键词： Graphene oxide,Optical microscope,Electrochemical technique,Reduced graphene oxide,XRD
更新于2025-09-09 09:28:46
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Reduced Graphene Oxide–TiO2 Nanotube Composite: Comprehensive Study for Gas Sensing Applications
摘要： Graphene oxide (GO) and reduced graphene oxide (RGO) have unique properties that can revolutionize performances of functional devices. Graphene-based materials can be coupled with metal oxide nanomaterials for gas sensing applications. In this work, we report the synthesis and the gas sensing properties of a composite material based on RGO loaded TiO2 nanotubes. To properly tune the reduction of GO to RGO we adopted a gas-phase process that can be applied in situ on each gas sensor device, allowing to track the process effects through the sensor conductance. We systematically investigated the gas-response dependence from RGO loading and its reduction, showing the occurrence of an optimal RGO concentration arising from the interplay of these two parameters. Hence, these two factors should be considered in parallel to functionalize the metal oxide materials with GO for the fabrication of chemical sensor devices.
关键词： TiO2 nanotube,gas sensing,reduced graphene oxide,reduction effect,surface functionalization,Graphene oxide
更新于2025-09-09 09:28:46
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Percolating Film of Pillared Graphene Layer Integrated with Silver Nanowire Network for Transparent and Flexible Supercapacitors
摘要： Transparent and flexible supercapacitors (TFSCs) are viable power sources for next-generation wearable electronics. The ingenious design of the transparent electrode determines the performance of TFSCs. Herein, a percolating film of a pillared graphene layer integrated with a silver nanowire network as the transparent electrode was prepared, by which TFSCs devices exhibit a significantly improved performance contrastively. At the condition of the same transmittance, about 27-72% improvement in the areal capacitance can be achieved. On the one hand, the pillars of carbon nanotube (CNT) were distributed in the graphene layer uniformly, enlarging the inner distance of adjacent graphene layers and providing open structure for extra ion transport and storage of TFSCs. On the other hand, the introduced CNT could facilitate the electron transport at the direction perpendicular to the graphene basal plane, enhancing the electronic conductivity of the graphene layer. More importantly, the formed percolating film ensures an efficient transport of electron along with the silver nanowire when it encounters the obstacle within the graphene layer, resulting in a highly conductive electrode. The TFSCs device with a good compatibility indicates a reliable practicability, which provides a facile route towards the design of high performance TFSCs.
关键词： reduced graphene oxide,silver nanowire,transparent supercapacitor,percolating film,flexible supercapacitor
更新于2025-09-09 09:28:46
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Role of reduced graphene oxide in dielectric enhancement of ferroelectric polymers composites
摘要： Flexible polymer composites with high dielectric constant are highly desirable for electrical and electronic applications. This work demonstrated the preparation of high-dielectric-constant (high-k) and low-dielectric-loss flexible composites by incorporating reduced graphene oxide (rGO) and the colossal-dielectric-constant CaCu3Ti4O12 (CCTO) particles in poly(vinylidene fluoride) matrix via solution processing. The three-phase composites combine the merits of each two-phase composite while avoiding the demerits of the two-phase composites. A high dielectric constant (～40.4) and relatively low dielectric loss tangent (～0.08) at 1 kHz were achieved when rGO and functionalized CCTO were 0.61 vol% of 12.5 vol%, respectively. The enhanced dielectric properties of the composites may originate from both induced polarization effect and intrinsic high dielectric constant of rGO, and the tunneling effect between rGO sheets play an important role in electrical conductivity and dielectric loss of the composites. It is believed that the ceramic/rGO/polymer three-phase hybrid strategy can be used to design and fabricate high-k composites with desirable flexibility and dielectric applications.
关键词： poly(vinylidene fluoride),CaCu3Ti4O12,reduced graphene oxide,dielectric constant
更新于2025-09-09 09:28:46
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Simultaneous reduction and surface functionalization of graphene oxide for highly conductive and water dispersible graphene derivatives
摘要： A simple and effective preparation method for the simultaneous reduction and functionalization of graphene oxide (rGO) by 2,4-diamino benzene sulfonic acid has been developed. The derivatives exhibit excellent conductivity and high dispersibility in various solvents. The successful preparation of rGO and the presence of the sulfonated aromatic diamine on rGO surface has been confirmed by infrared and X-ray photoelectron spectroscopy, while, the analysis by micro-Raman spectroscopy indicated that the reduction/functionalization alters the lattice structure of GO by the increment the defect density when the 2,4-diamino benzene sulfonic acid is used. Moreover, the study of the dried products by X-ray diffraction spectroscopy suggested the turbostratic restacking of the exfoliated rGO into graphite-like nanostructures. The obtained derivative of simultaneous reduction and functionalization of GO was used for the preparation of highly conductive water-based gravure ink, which in turn, was successfully applied in printing on various flexible substrates, demonstrating its great potentiality in graphene-based flexible and printed electronics applications.
关键词： Conductive inks,Printed electronics,Surface functionalization,Gravure,Reduced graphene oxide
更新于2025-09-09 09:28:46
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Reduced Graphene Oxide Nanostructures by Light: Going Beyond the Diffraction Limit
摘要： Graphene oxide (GO) offers excellent possibilities that are recently demonstrated in many applications ranging from biological sensors to optoelectronic devices. The process of thermal annealing aids in removing the oxygen-containing groups in GO, making GO more graphene-like, or the so-called reduced graphene oxide (rGO). Thermal reduction can also be achieved by intense light. Here, we demonstrate a scalable, inexpensive, and environmentally friendly method to pattern graphene oxide films beyond the diffraction limit of light using a conventional laser. We show that contrary to previous reports, non-linear effects that occur under high intensity conditions of laser irradiation allow the fabrication of highly conductive carbon nanowires with dimensions much smaller than the laser spot size. The potential of this method is illustrated by the fabrication of several devices on flexible and transparent substrates, including hybrid plasmonic/rGO sensors.
关键词： reduced graphene oxide,optoelectronic devices,laser reduction,Graphene oxide,diffraction limit
更新于2025-09-04 15:30:14
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Preparation of reduced Graphene Oxide (rGO) assisted by microwave irradiation and hydrothermal for reduction methods
摘要： Graphite is a natural carbon source that can be used for graphene synthesis because of its abundant availability and relatively low cost. In this research, Graphene Oxide (GO) and reduced Graphene Oxide (rGO) have been prepared through modified Hummers method that uses microwave irradiation and hydrothermal process as reduction methods. This research can be divided into two main steps, i.e. preparation of GO and preparation of rGO. The preparation of GO was done using modified Hummers method that refers to graphite powder oxidation for five days. Then, preparation of rGO was done using two methods, i.e. microwave irradiation for 8 minutes at 1,000 watts and hydrothermal process for 10 hours at 200°C. The characterization of the samples was observed by Fourier-Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Ultraviolet-Visible Spectroscopy (UV-Vis). XRD pattern of GO sample shows a peak at 2θ = 10.63°, rGO sample from hydrothermal process at 2θ = 25.94°, and rGO sample from microwave irradiation method at 2θ = 25.94° with low intensity and at 2θ = 10.63° that indicates the presence of GO. IR spectroscopy data shows an absorption peak of aromatic C=C at 1,573 cm-1 that indicates rGO formation. SEM images of GO illustrates a structure of stacked flakes. While the morphology of rGO has a structure of stacked flakes that is more transparent than GO. According to UV-Vis spectroscopy, GO and rGO of samples show absorption peak at λmax = 225 nm and λmax = 274 nm, respectively, which indicates π→π* transition of aromatic C=C bond. Based on the results of this study, the preparation of rGO using modified Hummers that combined with hydrothermal reduction method is more effective than microwave irradiation reduction method.
关键词： Graphene Oxide,hydrothermal process,Hummers method,reduced Graphene Oxide,microwave irradiation
更新于2025-09-04 15:30:14
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Synthesis and Characterizations of Zinc Oxide on Reduced Graphene Oxide for High Performance Electrocatalytic Reduction of Oxygen
摘要： Electrocatalysts for the oxygen reduction (ORR) reaction play an important role in renewable energy technologies, including fuel cells and metal-air batteries. However, development of cost effective catalyst with high activity remains a great challenge. In this feature article, a hybrid material combining ZnO nanoparticles (NPs) with reduced graphene oxide (rGO) is applied as an efficient oxygen reduction electrocatalyst. It is fabricated through a facile one-step hydrothermal method, in which the formation of ZnO NPs and the reduction of graphene oxide are accomplished simultaneously. Transmission electron microscopy and scanning electron microscopy profiles reveal the uniform distribution of ZnO NPs on rGO sheets. Cyclic voltammograms, rotating disk electrode and rotating ring disk electrode measurements demonstrate that the hierarchical ZnO/rGO hybrid nanomaterial exhibits excellent electrocatalytic activity for ORR in alkaline medium, due to the high cathodic current density (9.21 × 10?5 mA/cm2), positive onset potential (?0.22 V), low H2O2 yield (less than 3%), and high electron transfer numbers (4e from O2 to H2O). The proposed catalyst is also compared with commercial Pt/C catalyst, comparable catalytic performance and better stability are obtained. It is expected that the ZnO/rGO hybrid could be used as promising non-precious metal cathode in alkaline fuel cells.
关键词： reduced graphene oxide,zinc oxide,non-precious-metal catalyst,oxygen reduction reaction
更新于2025-09-04 15:30:14
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Structure of a Graphene-Modified Electroactive Polymer for Membranes of Biomimetic Systems: Simulation and Experiment
摘要： A model is proposed that describes the structure of water filled Nafion-graphene composite forming the body of an electroactive polymer membrane for actuators of biomimetic systems able to work in air and a liquid medium. The model predicts the growth of the ionic conductivity with increasing concentration of a graphene modifier, which is due to that the size of a part of clusters of the Nafion framework containing hydrophobic graphene flakes enlarges together with the pore size. Then the optimal concentration of the graphene modifier is reached, which provides the maximum ionic conductivity and actuation ability of the membrane as well as its elastic properties. The possibility of introducing into Nafion the modifier amount needed to improve the actuator operation is experimentally tested.
关键词： reduced graphene oxide,biomimetic systems,artificial muscle,graphene,electroactive polymers
更新于2025-09-04 15:30:14
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Electrical Conductivity of Reduced Graphene Oxide Thin-Film Layers
摘要： This work deals with the research of the electric properties of thin film layer of reduced graphene oxide. A structure of graphene oxide (GO) is represented by randomly distributed on a surface of substrate small islets of graphene with sp2 hybridized bonds surrounded by wide areas with sp3 bonds functionalized by oxygen groups. When electrons are confined in two-dimensional materials, quantum-mechanically enhanced transport phenomena such as the quantum Hall effect can be observed. Reduced graphene oxide, consisting of an isolated single atomic layer of graphite, is an ideal realization of such a two-dimensional system, therefore the partly semiconductive properties could be observed.
关键词： electrical conductivity,quantum Hall effect,reduced graphene oxide,thin-film layers,sp2 hybridized bonds
更新于2025-09-04 15:30:14