scholarly journals Pell-Shear-Exfoliation of few-layer graphene nanoflakes as an electrode in supercapacitors

2018 ◽  
Vol 6 (1) ◽  
pp. 1-10
Author(s):  
Ibrahem Aziz Mohammed
Keyword(s):  
Thin Films ◽  
Low Cost ◽  
Spray Coating ◽  
High Specific Capacitance ◽  
Optical Transmittance ◽  
High Quality ◽  
Layer Graphene ◽  
Graphene Nanoflakes ◽  
Wide Range ◽  
Few Layer Graphene

Introduction: The graphene has received a great attention because of its extraordinary characteristics of high carrier mobility, excellent thermal conductivity, high optical transmittance, and superior mechanical strength. Developing a simple methods with the property of producing large quantities of high-quality graphene have become essential for electronics, optoelectronics, composite materials, and energy-storage applications. Materials and Methods: In this study, the simple one step and efficient method of grinding was used to produce few-layers graphene nanoflakes from graphite. Different microscopic (TEM, SEM, and AFM) and spectroscopics (XRD, XPS, and Raman) charactrization tools were used to test the quality of the resultant graphene nanoflakes. Results: The produced nanoflakes showed no traces of oxidation due to the grinding process. In addition, the applicability of the obtained nanoflakes as potential supercapacitor electrodes was investigated. For that purpose, thin films of the few-layer graphene nanoflakes were developed using spray coating technique. In terms of both transparency and conductivity, the prepared films showed equivalent properties compared to those prepared by more complex methods. The electrochemical properties of the prepared electrodes showed high specific capacitance of 86 F g_1 at 10 A g_1 with excellent stability. The electrodes sustained their original capacity for more than 7000 cycles and started reducing to 72 F g−1 after 10000 cycles. Conclussions: The method provides a simple, efficient, versatile, and eco-friendly approach to low-cost mass production of high-quality graphene few-layers. The electrochemical stability and flexibility of the developed thin films indicated that the films could be used as electrodes in a wide range of electronic applications.

One-step synthesis and deposition of few-layer graphene via facile, dry ball-free milling

MRS Advances ◽  
2017 ◽  
Vol 2 (15) ◽  
pp. 847-856 ◽  
Author(s):  
Abdul Hai Alami ◽  
Kamilia Aokal ◽  
Mhd Adel Assad ◽  
Di Zhang ◽  
Hussain Alawadhi ◽  
...  
Keyword(s):  
Low Cost ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Hydrophobic Surface ◽  
Graphite Powder ◽  
High Energy ◽  
Layer Graphene ◽  
Wide Range ◽  
One Step ◽  
Few Layer Graphene

ABSTRACTGraphene is a 2-D carbon material showing considerable prominence in a wide range of optoelectronics, energy storage, thermal and mechanical applications. However, due to its unique features which are typically associated with difficulty in handling (ultra-thin thickness and hydrophobic surface, to name a few), synthesis and subsequent deposition processes are thus critical to the material properties of the prepared graphene films. While existing synthesis approaches such as chemical vapor deposition and epitaxial growth can grow graphene with high degree of order, the costly high temperature and/or high vacuum process prohibit the widespread usage, and the subsequent graphene transfer from the growth substrates for deposition proves to be challenging. Herein, a low-cost one-step synthesis and deposition approach for preparing few-layer graphene (FLG) on flexible copper substrates based on dry ball-free milling of graphite powder is proposed. Different from previous reports, copper substrates are inserted into the milling crucible, thus accomplishing simultaneous synthesis and deposition of FLG and eliminating further deposition step. Furthermore, while all previously reported high energy milling processes involve using balls of various sizes, we adopt a ball-free milling process relying only on centrifugal forces, which significantly reduces the surface damage of the deposition substrates. Sample characterization indicates that the process yields FLG deposited uniformly across all tested specimens. Consequently, this work takes graphene synthesis and deposition a step closer to full automation with simple and low-cost process.

Synthesis of High Quality Few Layer Graphene Sheets in Large Quantities by Radio Frequency Chemical Vapor Deposition

2009 ◽  
Vol 1204 ◽  
Author(s):  
Enkeleda Dervishi ◽  
Zhongrui Li ◽  
Fumiya Watanabe ◽  
Jimmy Shyaka ◽  
Abhijit Biswas ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Radio Frequency ◽  
Vapor Deposition ◽  
Low Cost ◽  
Chemical Vapor ◽  
Graphene Sheets ◽  
Scale Production ◽  
High Quality ◽  
Layer Graphene ◽  
Few Layer Graphene

AbstractThis work reports a low-cost method for large scale production of high quality graphene via radio-frequency chemical vapor deposition. High quantities of graphene were successfully synthesized on the Fe-Co/MgO (2.5:2.5:95 wt.%) catalytic system utilizing acetylene as a hydrocarbon source at 1000 °C. The as-produced graphene sheets were purified in a single step by washing with a diluted hydrochloric acid solution under sonication. Next, they were thoroughly characterized by microscopy, spectroscopy, and X-Ray diffraction. Advanced transmission electron microscopy and atomic force microscopy analyses have indicated the formation of 3-5 layered graphene nanosheets. Thorough analyses by Raman spectroscopy were also performed demonstrating the presence of high quality and few-layer graphene samples. This low cost and highly reproducible method may be applied in a straightforward way to produce large quantities of graphene for various advanced applications.

scholarly journals Growth of Ordered Graphene Ribbons by Sublimation Epitaxy

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 449
Author(s):  
Shuxian Cai ◽  
Xingfang Liu ◽  
Xin Zheng ◽  
Zhonghua Liu
Keyword(s):  
Substrate Surface ◽  
Graphene Film ◽  
Graphene Ribbon ◽  
High Quality ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Atomic Force ◽  
Few Layer Graphene

Ordered graphene ribbons were grown on the surface of 4° off-axis 4H-SiC wafers by sublimation epitaxy, and characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). SEM showed that there were gray and dark ribbons on the substrate surface, and AFM further revealed that these ordered graphene ribbons had clear stepped morphologies due to surface step-bunching. It was shown by μ-Raman that the numbers of graphene layers of these two types of regions were different. The gray region was composed of mono- or bilayer ordered graphene ribbon, while the dark region was of tri- or few-layer ribbon. Meanwhile, ribbons were all homogeneous and had a width up to 40 μm and a length up to 1000 μm, without micro defects such as grain boundaries, ridges, or mono- and few-layer graphene mixtures. The results of this study are useful for optimized growth of high-quality graphene film on silicon carbide crystal.

scholarly journals Biocarbon Meets Carbon—Humic Acid/Graphite Electrodes Formed by Mechanochemistry

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4032
Author(s):  
Lianlian Liu ◽  
Niclas Solin ◽  
Olle Inganäs
Keyword(s):  
Humic Acid ◽  
Low Cost ◽  
Graphene Sheets ◽  
Mechanochemical Method ◽  
Graphite Electrodes ◽  
Conductive Materials ◽  
Layer Graphene ◽  
Redox Active ◽  
Few Layer Graphene ◽  
Alcoholic Hydroxyl

Humic acid (HA) is a biopolymer formed from degraded plants, making it a ubiquitous, renewable, sustainable, and low cost source of biocarbon materials. HA contains abundant functional groups, such as carboxyl-, phenolic/alcoholic hydroxyl-, ketone-, and quinone/hydroquinone (Q/QH2)-groups. The presence of Q/QH2 groups makes HA redox active and, accordingly, HA is a candidate material for energy storage. However, as HA is an electronic insulator, it is essential to combine it with conductive materials in order to enable fabrication of HA electrodes. One of the lowest cost types of conductive materials that can be considered is carbon-based conductors such as graphite. Herein, we develop a facile method allowing the biocarbon to meet carbon; HA (in the form of a sodium salt) is mixed with graphite by a solvent-free mechanochemical method involving ball milling. Few-layer graphene sheets are formed and the HA/graphite mixtures can be used to fabricate HA/graphite hybrid material electrodes. These electrodes exhibit a conductivity of up to 160 S·m−1 and a discharge capacity as large as 20 mAhg−1. Our study demonstrates a novel methodology enabling scalable fabrication of low cost and sustainable organic electrodes for application as supercapacitors.

scholarly journals Reshaping Hybrid Perovskites Emission with Flexible Polymer Microcavities

2020 ◽  
Vol 230 ◽  
pp. 00006
Author(s):  
Paola Lova ◽  
Paolo Giusto ◽  
Francesco Di Stasio ◽  
Giovanni Manfredi ◽  
Giuseppe M. Paternò ◽  
...  
Keyword(s):  
Thin Films ◽  
Photonic Crystals ◽  
Low Cost ◽  
Scale Production ◽  
Large Area ◽  
Light Emitting Devices ◽  
Flexible Polymer ◽  
Hybrid Perovskite ◽  
Wide Range ◽  
Solution Processable

Thanks to versatile optoelectronic properties solution processable perovskites have attracted increasing interest as active materials in photovoltaic and light emitting devices. However, the deposition of perovskite thin films necessitates wide range solvents that are incompatible with many other solution-processable media, including polymers that are usually dissolved by the perovskite solvents. In this work, we demonstrate that hybrid perovskite thin films can be coupled with all polymer planar photonic crystals with different approaches to achieve emission intensity enhancement and reshaping using different approaches. The possibility to control and modify the emission spectrum of a solution processable perovskite via a simple spun-cast polymer structure is indeed of great interest in optoelectronic applications requiring high color purity or emission directionality. Furthermore, thanks to the ease of fabrication and scalability of solution-processed photonic crystals, this approach could enable industrial scale production of low-cost, large area, lightweight and flexible polymer-perovskite lighting devices, which may be tuned without resorting to compositional engineering.

Effect of Flexible Substrates on the Structural and Optical Properties of ZnO Films Deposited by Sputtering Method

2015 ◽  
Vol 1107 ◽  
pp. 678-683 ◽  
Author(s):  
Lam Mui Li ◽  
Azmizam Manie Mani ◽  
Saafie Salleh ◽  
Afishah Alias
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Low Cost ◽  
Argon Plasma ◽  
Optical Transmittance ◽  
Zno Thin Films ◽  
Plastic Substrate ◽  
Zno Films ◽  
X Ray Diffraction ◽  
X Ray

Zinc Oxide (ZnO) has attracted much attention because of its high optical transmittance approximately ~80 % with a wide band gap of (3.3 eV at 300 K) and a relatively low cost material. ZnO thin films were deposited on plastic substrate using RF powered magnetron sputtering method. The target used is ZnO disk with 99.99 % purity. The sputtering processes are carried out with argon gas that flow from 10-15 sccm. Argon is used to sputter the ZnO target because the ability of argon that can remove ZnO layer effectively by sputtering with argon plasma bombardment. The deposited ZnO thin films are characterized using X-Ray Diffraction (XRD) and UV-Vis Spectrometer. The analysis of X-ray diffraction show that good crystalline quality occurs at nominal thickness of 400 nm. The optical studies showed that all the thin films have high average transmittance of approximately 80 % and the estimated value of optical band gap is within 3.1 eV-3.3 eV range.

Photoconductivity Measurements of Organic Polymer/Nanostructure Blends

2010 ◽  
Vol 1270 ◽  
Author(s):  
David Black ◽  
Shashi Paul
Keyword(s):  
Low Cost ◽  
Spectroscopic Studies ◽  
Organic Polymer ◽  
Photovoltaic Devices ◽  
Solar Simulator ◽  
High Quality ◽  
Polymer Nanoparticle ◽  
Wide Range ◽  
Coated Film ◽  
Polymer Nanostructure

AbstractIn an attempt to produce low cost and high quality polymer/nanoparticle blends for use in hybrid organic/inorganic photovoltaic devices we prepared blends of dihexylsexithiophene and tetragonal barium titanate particles. These polymer nanoparticle blends were deposited as films by spin coating and sublimation. The films were characterised and compared using a wide range of techniques; The electrical photoconductivity analysis of these structures carried out using an HP4140B picoammeter and a solar simulator after aluminium gap cell electrodes had been deposited on the films by sublimation, spectroscopic studies (FTIR and UV-VIS) were carried out to understand the photoconductivity measurements and ellipsometry was used to determine the thickness of the films. The photoconductivity of the spin coated films was the highest reaching 8.5x 10-10A at 20 V, the sublimed films reached ~4 x 10-10A at 40V. This is thought to be due to the thinness of the sublimed films combined with the inhomogeneous distribution of nanoparticles compared with the spin coated film. Sublimed films have been shown by others to be better structured than spin coated films, if this property can be utilized with further optimization of the sublimation process then this technique offers the potential to produce very thin high quality films for use in organic and hybrid photovoltaic devices.

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