Showing papers on "Graphene oxide paper published in 2020"

Continuous crystalline graphene papers with gigapascal strength by intercalation modulated plasticization

Abstract: Graphene has an extremely high in-plane strength yet considerable out-of-plane softness. High crystalline order of graphene assemblies is desired to utilize their in-plane properties, however, challenged by the easy formation of chaotic wrinkles for the intrinsic softness. Here, we find an intercalation modulated plasticization phenomenon, present a continuous plasticization stretching method to regulate spontaneous wrinkles of graphene sheets into crystalline orders, and fabricate continuous graphene papers with a high Hermans’ order of 0.93. The crystalline graphene paper exhibits superior mechanical (tensile strength of 1.1 GPa, stiffness of 62.8 GPa) and conductive properties (electrical conductivity of 1.1 × 105 S m−1, thermal conductivity of 109.11 W m−1 K−1). We extend the ultrastrong graphene papers to the realistic laminated composites and achieve high strength combining with attractive conductive and electromagnetic shielding performance. The intercalation modulated plasticity is revealed as a vital state of graphene assemblies, contributing to their industrial processing as metals and plastics. Strong but flexible graphene tends to wrinkle, which compromises some properties. Here the authors report a solid plasticization method to prepare continuous graphene papers with high crystalline order, achieving high strength, stiffness, electrical and thermal conductivities.

Processing and out-of-plane properties of composites with embedded graphene paper for EMI shielding applications

Abstract: This study focuses on the evaluation of the effects of incorporating a thin layer (‘paper’) of Graphene nanoplatelets (GnP) between the lamina on the processability and out-of-plane performance of glass fiber composites for EMI shielding applications. Various thicknesses of GnP paper (50, 120, and 240 µm) were embedded within layers of glass fabric for subsequent resin infusion. The out-of-plane failure surfaces were evaluated using a purpose-built fixture. In all experiments, the separation was observed within the graphene layers of the GnP paper rather than at composite/GnP interface. In comparison to pristine samples, decreases of 252%, 305%, and 386% respectively were recorded in the out-of-plane strength of embedded GnP papers. Numerical simulations were completed using a bilinear traction separation law based on the cohesive zone modeling approach. All composites were tested for electromagnetic interference (EMI) shielding properties. The EMI shielding was improved significantly by embedding GnP paper within glass fiber composites.

Light-Powered Directional Nanofluidic Ion Transport in Kirigami-Made Asymmetric Photonic-Ionic Devices.

Abstract: Nacre-mimetic 2D nanofluidic materials with densely packed sub-nanometer-height lamellar channels find widespread applications in water-, energy-, and environment-related aspects by virtue of their scalable fabrication methods and exceptional transport properties. Recently, light-powered nanofluidic ion transport in synthetic materials gained considerable attention for its remote, noninvasive, and active control of the membrane transport property using the energy of light. Toward practical application, a critical challenge is to overcome the dependence on inhomogeneous or site-specific light illumination. Here, asymmetric photonic-ionic devices based on kirigami-tailored graphene oxide paper are fabricated, and directional nanofluidic ion transport properties therein powered by full-area light illumination are demonstrated. The in-plane asymmetry of the graphene oxide paper is essential to the generation of photoelectric driving force under homogeneous illumination. This light-powered ion transport phenomenon is explained based on a modified carrier diffusion model. In asymmetric nanofluidic structures, enhanced recombination of photoexcited charge carriers at the membrane boundary breaks the electric potential balance in the horizontal direction, and thus drives the ion transport in that direction under symmetric illumination. The kirigami-based strategy provides a facile and scalable way to fabricate paper-like photonic-ionic devices with arbitrary shapes, working as fundamental elements for large-scale light-harvesting nanofluidic circuits.

Carbon Black and Reduced Graphene Oxide Nanocomposite for Binder-Free Supercapacitors with Reduced Graphene Oxide Paper as the Current Collector

Abstract: Reduced graphene oxide (rGO) is an ideal candidate for the improvement of supercapacitor (SC) performances due to its industrial-ready manufacturing process and ease of processing. In this work, rGO was used as an active binder for the manufacture of carbon black (CB) and rGO-based SCs. Being able to form a stable suspension in water, graphene oxide (GO) was initially exploited as a dispersing agent to fabricate a homogeneous slurry with CB having exclusively water as a low-cost and environment-friendly solvent. After casting on a suitable substrate, the material was subjected to thermal treatment allowing the reduction of GO to rGO, which was successively confirmed by chemical-physical analysis. An innovative current collector, consisting of high-quality rGO paper, was also proposed ensuring an improved adhesion between the active material and the substrate and a reduction of the whole weight with respect to devices fabricated using common metallic current collectors. Due to the interesting electrochemical performances, with a high specific power of 32.1 kW kg-1 and a corresponding specific energy of 8.8 Wh kg-1 at a current of 1 A g-1, and the improved manufacturing process, the described "all-graphene-based" device represents a valuable candidate for the future of SCs.

Tuning solid–air interface of porous graphene paper for enhanced electromagnetic interference shielding

Abstract: Electromagnetic interference (EMI) shielding materials with high performance and low density are urgently needed with the rapid development of electronic communications. In this work, tuning solid–air interface of graphene paper was carried out to enhance multiple reflections of incident electromagnetic waves for high-performance EMI shielding. The large amount solid–air interface (57.8 m2 g−1) endowed the porous graphene paper with a high EMI shielding effectiveness (SE) of 31.0 dB, 50% enhancement from its counterpart of solid graphene paper. This porous graphene paper also showed an ultralow density of 0.02 g cm−3, an 18.5-fold decrease from its counterpart of solid graphene paper. Moreover, the EMI SE of obtained graphene papers exhibited proportional relationship with their specific surface area, further confirming the vital role of solid–air interface in the enhancement of EMI shielding. This work quantitatively demonstrates the significance of solid–air interface area for enhancing the EMI shielding performance and proposes an efficient guideline for the design of high-performance and low-density EMI shielding materials.

Surface-tailored graphene oxide paper: an efficient filter for dye pollutants

Abstract: The potential application of graphene as a filter paper for selectively removing cationic and anionic dyes from aqueous solutions is demonstrated herein. A surface-tailored graphene paper was fabricated by the vacuum filtration technique on a microporous substrate to remove two different classes of dyes. A negatively charged graphene paper was fabricated from graphene oxide (GO) solution, and a positively charged graphene paper was fabricated from polyallylamine-functionalized GO solution. The solutions of methylene blue (MB) and methyl orange (MO) were filtered through the negatively charged graphene paper (GO−) and positively charged graphene paper (GO+). The stacking structure of the GO− and GO+ paper successfully removed the MB and MO mixtures from the solution. The GO− and GO+ paper demonstrated a high retention rate of 99.8% for MB dye and 99.5% for MO dye. The pore size of the paper was found to be less than 7 nm, providing more insights into the rejection mechanism. The rejection mechanism involves the adsorption and electrostatic interaction (i.e., cationic–anionic interaction) between the dye and graphene sheets, which result in the fast and efficient removal of the dye. The GO paper displayed adsorption capacities as high as 311 and 340 mg g−1 for MB and MO dyes, respectively. The results indicate that the surface-tailored graphene paper is a great alternative for the next generation cost-effective filters in practical water purification applications.

Coordination polymer nanowires/reduced graphene oxide paper as flexible anode for sodium-ion batteries

Abstract: 构建基于有机材料的高性能柔性储钠电极面临诸多挑战. 本 工作通过可控组装及还原的方式, 实现了铁基配位聚合物纳米线/还原氧化石墨烯柔性薄膜的构筑. 多维复合薄膜可直接用作钠离 子电池自支撑负极, 且具有较高的储钠容量(200 mA g−1电流密度 下可逆容量为319 mA h g−1)和优异的倍率性能(3000 mA g−1大电 流密度下比容量可保持在∼120 mA h g−1). 研究表明有机配体(氨 三乙酸)中的羧基及氨基为储钠活性位点, 而配位金属离子(Fe2+)不 参与电化学反应.

Dense integration of graphene paper positive electrode materials for aluminum-ion battery

Abstract: Although Al-ion battery is attracting researchers’ attention worldwide, its volumetric energy density was not so promising due to low density of graphite-based positive electrodes in the current published literatures. Thus, defect-free yet densely packed graphene electrodes with high electronic conductivity and fast ionic diffusion are crucial to the realization of compacted Al-ion batteries with high volumetric energy density. In the present work, a self-supported and defect-free graphene-positive electrode (RHG-P-2850) was successfully produced by a hydriodic acid reduction of the graphene oxide (GO) method, followed by an ultrahigh temperature (2850 °C) annealing treatment. The density of the RHG-P-2850 (0.32 g cm−3) is currently the highest positive electrode material in the preparation of graphene-positive electrodes from GO. RHG-P-2850 positive electrode enables to deliver considerably high specific capacity 27.1 mAh cm−3 (85 mAh g−1) at the current density 2 A g−1. More importantly, a remarkably stable performance was achieved with 20% fading over 8000 cycles. The results enlighten and promote the design and preparation of densely packed graphene-positive electrode to develop high-performance Al/graphene battery.

Synthesis of reduced graphene oxide paper for EMI shielding by a multi-step process

Abstract: A multi-step reduction process was developed to produce reduced graphene oxide (rGO) paper for electromagnetic interference (EMI) shielding. First step reduction was achieved by hydroiodic acid to ...

Experimental and theoretical studies of a thermal switch based on shape-memory alloy cladded with graphene paper

Abstract: Thermal switches control thermal circuits and are widely used in electronics and engineering. Shape-memory alloys can be deformed by heating, which is widely used as a driving part for ther...

Direct Synthesis of Graphene Dendrites on SiO 2 /Si Substrates by Chemical Vapor Deposition

Abstract: The long-standing interest in graphene has recently brought graphene-derived materials including graphene hydrogel, graphene fiber and graphene paper into sharp focus. These graphene-derived materials show outstanding properties in mechanics and physics. In this paper, for the first time, we demonstrate the novel synthesis of graphene dendrites on SiO2/Si substrates by chemical vapor deposition. The tree-like graphene dendrites with well-controlled morphology can be directly grown on both the Si and the SiO2 surfaces of the substrates by using methane and hydrogen as precursors. The graphene dendrites on SiO2/Si substrates can be directly used in the fabrication of the electronic device. The conductivity and the Hall mobility of graphene dendrites are ~ 286 Scm−1 and ~ 574 cm2(Vs)−1, respectively. Young’s modulus of graphene dendrites is up to 2.26 GPa. The developed method avoids the need for a metal substrate and is scalable and compatible with the existing semiconductor technology, making graphene dendrites be very promising in nanoelectronic applications.

The enhanced thermal transport properties of a heat spreader assembled using non-covalent functionalized graphene

Abstract: Though graphene paper consisting of layer-by-layer stacked graphene nanosheets (GNs) has been widely used as a heat spreader due to the high in-plane thermal conductivity, the drawback of graphene paper is that it shows low through-plane thermal conductivity at the same time. In this study, polyamine-functionalized perylene bisimide derivative (APBI)/graphene nanosheet hybrid paper (AGP) samples with a “brick-and-mortar” structure were fabricated via the noncovalent functionalization of GNs and APBI. APBI can not only greatly improve the through-plane thermal transport but it also improves the mechanical properties of AGP. The through-plane thermal conductivity of AGP reaches 6.67 W m−1 K−1 with 42.36 wt% APBI and the tensile strength of AGP reaches 47.9 MPa with 14.22 wt% APBI. AGP, with both good thermal transport properties and mechanical properties, is expected to be used for thermal management applications as a heat spreader in industry.

Method capable of obtaining flexible graphene current collectors in batches

Abstract: The invention discloses a method capable of obtaining flexible graphene current collectors in batches. The method comprises the following steps: (1) mixing concentrated sulfuric acid and crystalline flake graphite so as to prepare a mixed solution; (2) adding hydrogen peroxide with a concentration of 30% into the mixed solution, carrying out stirring, then carrying out standing at a normal temperature, carrying out washing with water, and carrying out drying so as to obtain graphene powder; and (3) rolling the graphene powder into paper by using a rolling technology, then carrying out annealing, and carrying out rolling again so as to obtain flexible graphene paper. According to the preparation method for the flexible graphene current collectors provided by the invention, the flexible graphene current collectors with high conductivity, light weight and hydrophilicity can be obtained in batches by using rolling equipment through simple and low-cost puffing stripping and rolling technologies and preparation from powder to paper.

The Influence of Laser Ablation Parameters on the Holes Structure of Laser Manufactured Graphene Paper Microsieves.

Abstract: The graphene paper microsieves can be applied in the filtration of biological fluids or separation of solid particles from exploitation fluids. To produce graphene paper microsieves for specific applications, good control over fabrication should be achieved. In this study, a laser ablation method using a picosecond laser was applied to fabricate graphene paper microsieves. Holes in the microsieves were drilled using pulsed laser radiation with a pulse energy from 5 to 100 µJ, a duration of 60 ps, a wavelength of 355 nm, and a repetition rate of 1 kHz. The impact method was applied using 10 to 100 pulses to drill one hole. To produce holes of a proper diameter which could separate biological particles of a certain size (≥10 µm), optimum parameters of graphene paper laser ablation were defined using the MATLAB software taking into account laser pulse energy, repetition rate, and a desired hole diameter. A series of structural tests were carried out to determine the quality of an edge and a hole shape. Experimental results and Laguerre-Gauss calculations in MATLAB were then compared to perform the analysis of the distribution of diffraction fringes. Optimum experimental parameters were determined for which good susceptibility of the graphene paper to laser processing was observed.

Flexible and free-standing MnO x /reduced graphene oxide paper with excellent cycling stability for Li-ion battery anode

Abstract: In this study, the performance of manganese oxide nanorods/reduced graphene oxide (MnOx/rGO) composite papers as anode for lithium-ion battery is investigated. The self-supporting and flexible composite papers are fabricated via traditional vacuum filtration. The crystal structure, chemical state and morphology are determined by XRD, XPS and SEM, respectively. And the electrochemical performance is measured by means of cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) techniques. It is proved that the MnOx/rGO papers exhibit layer-by-layer structure in which rod-shaped MnOx is sandwiched among the rGO sheets. As anode for lithium-ion batteries, the capacity of MnOx/rGO paper can be stabilized at 518 mAh g−1 for 1500 charge/discharge cycles.