Showing papers on "Graphene oxide paper published in 2018"
TL;DR: The hybrid exhibits superior activity towards the hydrogen evolution reaction with low onset potentials of 11 mV (0.5 m H2 SO4 ) and 18mV (1 m KOH) as well as remarkable stability.
Abstract: An in situ catalytic etching strategy is developed to fabricate holey reduced graphene oxide along with simultaneous coupling with a small-sized Mo2 N-Mo2 C heterojunction (Mo2 N-Mo2 C/HGr). The method includes the first immobilization of H3 PMo12 O40 (PMo12 ) clusters on graphite oxide (GO), followed by calcination in air and NH3 to form Mo2 N-Mo2 C/HGr. PMo12 not only acts as the Mo heterojunction source, but also provides the Mo species that can in situ catalyze the decomposition of adjacent reduced GO to form HGr, while the released gas (CO) and introduced NH3 simultaneously react with the Mo species to form an Mo2 N-Mo2 C heterojunction on HGr. The hybrid exhibits superior activity towards the hydrogen evolution reaction with low onset potentials of 11 mV (0.5 m H2 SO4 ) and 18 mV (1 m KOH) as well as remarkable stability. The activity in alkaline media is also superior to Pt/C at large current densities (>88 mA cm-2 ). The good activity of Mo2 N-Mo2 C/HGr is ascribed to its small size, the heterojunction of Mo2 N-Mo2 C, and the good charge/mass-transfer ability of HGr, as supported by a series of experiments and theoretical calculations.
447 citations
TL;DR: The applications of organo-functionalized GO composites for the adsorption of heavy metals and some perspectives on the future research needs are offered.
315 citations
TL;DR: In this paper, the chemical exfoliation and thermal annealing methods are appraised as an inventive route towards the production of graphene at prodigious scale, which is used for the oxidation of graphite flakes having an oxidizing specialist.
265 citations
TL;DR: In this article, a high alignment of graphene nanosheets (GNSs) in GNS/Cu composites was achieved through a vacuum filtration method followed by spark plasma sintering.
217 citations
TL;DR: In this article, the authors reported an efficient route to prepare the graphene nanoplatelet (GNP)/Cu composites with highly aligned GNPs by a vacuum filtration method followed by spark plasma sintering.
206 citations
TL;DR: In this paper, a new strategy for fabricating the super-hydrophobic, electrically conductive and mechanically flexible porous GONR based composites, showing promising application in strain sensor and oil pollution remediation fields at different environmental conditions.
187 citations
TL;DR: In this paper, a single-atom catalysts (SAC) with reduced graphene oxide (RGO) as the inner shell and carbon nanospheres as the outer shell is presented.
Abstract: The maximized atomic efficiency of supported catalysts is highly desired in heterogeneous catalysis. Therefore, the design and development of active, stable, and atomic metal-based catalysts remains a formidable challenge. To tackle these problems, it is necessary to investigate the interaction between single atoms and supports. Theoretical calculations indicate that the Pd binding strength is higher on graphene/amorphous carbon (AC) than that on graphene or AC substrate. Based on these predictions, we present a facile confined-interface-directed synthesis route for the preparation of single-atom catalysts (SACs) in which Pd atoms are well-dispersed on the interface of double-shelled hollow carbon nanospheres with reduced graphene oxide (RGO) as the inner shell and AC as the outer shell. Owing to the synergetic effect of the RGO/AC confined interface and the atomically dispersed Pd, the as-made RGO@AC/Pd SAC achieves the maximum atomic efficiency (catalytic activity) of Pd species and exhibits an excellent stability in chemical catalysis. This confined-interface-directed synthesis method provides a novel direction to maximize the atomic efficiency, improve the activity, and enhance the stability of metal-based catalysts.
139 citations
TL;DR: In this paper, a multi-layer graphene embedded composite of aluminium alloys by direct exfoliation of graphite into graphene with the help of Friction Stir Alloying (FSA) was reported.
Abstract: The paper reports manufacturing of a multi-layer graphene embedded composite of aluminium alloys by direct exfoliation of graphite into graphene with the help of Friction Stir Alloying (FSA). The formation of this nano composite and optimization of the process parameters led to an approximately two-fold increase in the strength, without loss in ductility, due to the dispersion of the graphene in aluminium. The manufacturing process is scalable and cost effective as it uses graphite powder and aluminium sheets as the raw materials. The presence of graphene layers in the metal matrix was confirmed using Raman spectroscopy as well as TEM. The graphene sheet thickness was measured using AFM after extracting it from the composite. Molecular dynamic simulation results reveal the evolution of newer structures and defects that have resulted in the enhanced properties of the nano-composite. These findings open up newer possibilities toward efficient and scalable manufacturing of high strength high-ductility metal matrix based graphene nano-composites.
123 citations
118 citations
TL;DR: In this article, PdAg@ZrO2/C/rGO was successfully immobilized on zirconia/porous carbon/reduced graphene oxide, which has tremendous application prospects in various catalytic fields.
Abstract: Ultrafine PdAg nanoparticles (NPs) are successfully immobilized on zirconia/porous carbon/reduced graphene oxide (ZrO2/C/rGO) nanocomposite derived from metal organic framework/graphene oxide. Monodispersed PdAg NPs (diameter ≤2.5 nm) can be facilely anchored on the ZrO2/C/rGO and the aggregation of metal NPs can be avoided utmostly. By virtue of the synergistic effect between metal NPs and support, the resulting PdAg@ZrO2/C/rGO exhibits excellent activity (turnover frequency, 4500 h−1 at 333 K) for the dehydrogenation of formic acid. As an effective strategy, it provides an opportunity to immobilize ultrafine metal NPs on metal oxide/porous carbon/reduced graphene oxide, which has tremendous application prospects in various catalytic fields.
98 citations
TL;DR: A novel strategy is reported for production of freestanding GP through LIG technology and it is determined that the unique spatial configuration of polyimide (PI) paper is critical for the preparation of GP without the appearance of intense shape distortion.
Abstract: The recently emergent laser-induced graphene (LIG) technology has endowed the fabrication of smart devices with one-step processing and scalable/designable features. Graphene paper (GP), an important architecture of 2D layered carbon, however, is never produced through LIG. Herein, a novel strategy is reported for production of freestanding GP through LIG technology. It is first determined that the unique spatial configuration of polyimide (PI) paper is critical for the preparation of GP without the appearance of intense shape distortion. Benefiting from the mechanism, the as-produced laser-induced graphene paper (LIGP) is foldable, trimmable, and integratable to customized shapes and structures with the largest dimension of 40 × 35 cm2 . Based on the processing-structure-property relationship study, one is capable of controlling and tuning various physical and chemical properties of LIGPs, rendering them unique for assembling flexible electronics and smart structures, e.g., human/robotic motion detectors, liquid sensors, water-oil separators, antibacterial media, and flame retardant/deicing/self-sensing composites. With the key findings, the escalation of LIGP for commercialization, roll-to-roll manufacturing, and multidisciplinary applications are highly expected.
TL;DR: In this paper, the authors used Scanning-Raman-Microscopy (SRM) to characterize films of graphene derived from flakes of graphene oxide with an almost intact carbon framework (ai-GO).
Abstract: Graphene oxide can be used as a precursor to graphene but the quality of graphene flakes is highly heterogeneous. Scanning-Raman-Microscopy (SRM) is used to characterize films of graphene derived from flakes of graphene oxide with an almost intact carbon framework (ai-GO). The defect density of these flakes is visualized in detail by analyzing the intensity and full-width at half-maximum of the most pronounced Raman peaks. In addition, we superimpose the SRM results with AFM images and correlate the spectroscopic results with the morphology. Furthermore, we use SRM technique to display the amount of defects in a film of graphene. Thus, an area of 250 x 250 {\my}m2 of graphene is probed with a step-size increment of 1 {\mu}m. We are able to visualize the position of graphene flakes, edges and the substrate. Finally, we alter parameters of measurement to analyze the quality of graphene fast and reliable. The described method can be used to probe and visualize the quality of graphene films.
TL;DR: In this paper, a flexible asymmetric supercapacitor using a 3D porous reduced graphene oxide/manganese dioxide@polyaniline (RGO/MnO2@PANI) hybrid film as the positive electrode and a self-assembled 3D pillared graphene aerogel as the negative electrode material with a polyvinyl alcohol/potassium hydroxide (PVA/KOH) gel electrolyte was presented.
Abstract: There is an increasing demand for safe, environmentally benign energy storage devices in portable electronic appliances, wearable gadgets, flexible displays, and other personal multimedia devices. In this study, we have fabricated an all-solid-state flexible asymmetric supercapacitor using a novel 3D porous reduced graphene oxide/manganese dioxide@polyaniline (RGO/MnO2@PANI) hybrid film as the positive electrode and a self-assembled 3D pillared graphene aerogel as the negative electrode material with a polyvinyl alcohol/potassium hydroxide (PVA/KOH) gel electrolyte. The flexible composite film was synthesized by vacuum filtration of GO and a MnO2@PANI mixture followed by chemical reduction of the resulting film in a hydrothermal autoclave. The 3D graphene aerogel was synthesized by a hydrothermal route using a solution of the nonionic triblock copolymer Pluronic F-68 as a soft template and vitamin C as a reducing agent. Herein, the Pluronic copolymer played dual roles: first, it enabled the effective dispersion of graphene oxide in water, and second, it assisted the formation of a stable 3D pillared hydrogel assembly. The RGO/MnO2@PANI-based symmetric supercapacitor shows a high energy density of 18.33 W h kg−1 at a power density of 0.388 kW kg−1. An asymmetric supercapacitor (graphene aerogel//RGO/MnO2@PANI), which was fabricated by optimizing the individual electrode materials, exhibited a very high energy density of 38.12 W h kg−1 at a power density of 1.191 kW kg−1 utilizing a large potential window of 1.5 V. Moreover, 3 cells connected in series successfully lit up a red LED for 45 s and displayed similar performance under bending conditions.
TL;DR: In this paper, a hybrid nanocomposite of cellulose fiber/multi-walled carbon nanotube (MWCNT)/reduced graphene oxide (rGO)/Cobalt oxide (Co3O4)/tin oxide (SnO2) is synthesized via a hydrothermal method for supercapacitor applications and characterized for their electrochemical performance and thermal stability.
Abstract: In this paper, a hybrid nanocomposite of cellulose fiber/multi-walled carbon nanotube (MWCNT)/reduced graphene oxide (rGO)/Cobalt oxide (Co3O4)/tin oxide (SnO2) is synthesized via a hydrothermal method for supercapacitor applications and characterized for their electrochemical performance and thermal stability. The morphology of the nanocomposites was characterized by using scanning electron microscope (SEM) and transmission electron microscope (TEM). Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy were used to determine the chemical groups and crystal structure. Energy dispersive X-ray spectroscopy (EDX) confirmed the constitutional proportions of various elements in the composite. The electrode was fabricated from the nanocomposite and characterized by cyclic voltammetry (CV) that showed good cyclic stability with 88% capacitance retention after 1000 cycles and a capacitance of 215 F g−1 and 181 F g−1at a current density of 0.2 A g−1and 0.4 A g−1, respectively. The hybrid nanocomposite showed higher thermal stability than cellulose fiber/MWCNT and cellulose fiber/MWCNT/rGO composites. This simple, scalable and low-cost approach could open new opportunities for next-generation energy storage devices.
TL;DR: In this paper, a surfactant-free colloidal solution comprised of copper (II)-ethylene diamine tetra acetic acid ([CuIIEDTA]2−) complexes and graphene oxide (GO) sheets is proposed to electrodeposit reduced graphene oxide/copper (RGO/Cu) composite coatings.
TL;DR: In this article, a rapid, one-step electron-beam based method for both reduction of graphene oxide (GO) and co-doping of nitrogen and sulfur to prepare N, S-codoped graphene layers (NSG) has been achieved.
TL;DR: In this article, a quasi-isotropic graphene framework (QIGF) was used as a filler to reduce the lateral size of filtrated graphene sheets, which achieved a thermal conductivity of 10.0 and 5.4 W mK−1, respectively.
Abstract: Vacuum filtration is a highly effective and easy scale-up approach and has been widely used to fabricate graphene monoliths, such as graphene paper and graphene frameworks for various applications. In general, the microstructure of filtrated monoliths exhibits layer-by-layer stacking of graphene sheets due to the directional flow-induced assembly process. In this work, we found that the horizontally oriented structure of filtrated graphene frameworks can be modulated to an approximately isotropic arrangement by lowering the lateral size of graphene sheets. This size-dependent microstructure transition from anisotropic to isotropic was further confirmed by measuring the in- and through-plane thermal conductivity of the graphene/epoxy composites with different arrangements of graphene frameworks as a filler. Optimally, we obtained an epoxy composite embedded with a quasi-isotropic graphene framework (QIGF) by a simple two-step process: vacuum filtration of small graphene sheets to obtain the framework followed by the infiltration of epoxy resin. Based on the interconnected graphene sheets with an approximately isotropic arrangement, QIGF provides heat channels of graphene–graphene along both the in- and through-plane directions within epoxy. With a low graphene loading of 5.5 wt%, QIGF/epoxy (QIGF/EP) presents in- and through-plane thermal conductivities of 10.0 and 5.4 W mK−1, respectively, which are equivalent to ∼55 and 29 times higher than those of neat epoxy. As compared to the current graphene/epoxy composites prepared by various methods, our QIGF/EP has the highest thermal conductivity value with this level of filler loading. Our findings provide an insight for the development of polymer composites for thermal management applications in industry.
TL;DR: The laminated structure of graphene oxide (GO) confers unique interactions with water molecules which may be utilised in a range of applications that require materials with tuneable hygroscopic properties.
Abstract: The laminated structure of graphene oxide (GO) confers unique interactions with water molecules which may be utilised in a range of applications that require materials with tuneable hygroscopic properties. The precise role of the expandable interlayer spacing and functional groups in GO laminates has not completely been understood to date. Herein, we report the experimental and theoretical investigations on the adsorption and desorption behaviour of water in GO laminates as a function of relative pressure. We observed that GO imparts high water uptake capacity of up to 0.58 gram of water per gram of GO (g g−1), which is significantly higher than silica gel as a conventional desiccant material. More interestingly, the adsorption and desorption kinetics of GO is five times higher than silica gel. The observed extraordinary adsorption/desorption rate can be attributed to the high capillary pressure in GO laminates as well as micro meter sized tunnel-like wrinkles located at the surface.
TL;DR: In this article, a facile synthesis of reduced graphene oxide (RGO)/copper(Cu) composite with hierarchical layered structure based on molecular level mixing and self-assembly was investigated.
TL;DR: Li et al. as mentioned in this paper proposed a self-assembly method to fabricate high-performance, large-area graphene oxide/electrochemically exfoliated graphene hybrid films for heater applications.
TL;DR: In this article, a non-electrified electrochemical exfoliation method was proposed to produce high quality graphene (NEEG) sheets by direct electrochemical reaction between graphite powders and metallic Li in 1M LiPF6/propylene carbonate electrolyte.
TL;DR: In this article, the authors combined both electrical characterization and Raman spectroscopy to study the contact resistance issue in graphene field effect transistor (FET) and found that the graphene-metal contact resistance is a significant contributor to the total resistance.
TL;DR: In this paper, a high-yield, scalable electrochemical exfoliation method in a ternary deep eutectic melts containing acetamide, urea and ammonium nitrate was proposed.
TL;DR: Wang et al. as discussed by the authors used high temperature CVD without the use of metal catalysts to fabricate a sapphire-based G-FET, which was patterned and made into a DNA biosensor.
TL;DR: In this article, the authors presented a novel graphene fabric gas sensor composed of reduced graphene oxide (RGO) nanosheets and electrospun nylon-6 nanofibers.
Abstract: Flexible gas sensors with high-sensitivity and good stability are essential components of wearable electronic devices. In this paper, we present a novel graphene fabric gas sensor composed of reduced graphene oxide (RGO) nanosheets and electrospun nylon-6 nanofibers. By combination the RGO with nanofiber, the graphene electronic fabrics show sensitive response to NO 2 (13.6%@1 ppm) at room temperature, and excellent mechanical reliability against repeated deformation during 5000 bending cycles with an extreme bending radius of 1.0 mm.
TL;DR: In this article, a new method based on scanning atmospheric plasma for an ultrafast reduction of graphene oxide (GO) and preparation of highly conductive graphene films and patterns is presented, which can provide a direct and scalable fabrication of graphene films on flexible and shaped substrates with a variety of patterns for broad applications.
TL;DR: In this article, the optoelectronic characterization of graphene/silicon Schottky junctions is presented, fabricated by transferring CVD-graphene on flat and nanotip-patterned n-and p-type Si substrates.
Abstract: We present the optoelectronic characterization of graphene/silicon Schottky junctions, fabricated by transferring CVD-graphene on flat and nanotip-patterned n- and p-type Si substrates. We show that medium n-type doping results in the highest rectification. We demonstrate high photoresponsivity, exceeding 2.5 A/W under white light, which we attribute to the contribution of charges photogenerated in the surrounding region of the flat junction or to the internal gain by impact ionization caused by the enhanced field on the nanotips.
TL;DR: In this article, the authors presented a cost-effective and low-temperature (600°C) synthesis of edge-rich graphene paper for the cathode of Al batteries, which could effectively improve its performance in Al batteries.
TL;DR: Graphene is emerged as a highly sought after reinforcing filler for epoxy matrix in view of its superior electrical, mechanical and thermal properties as discussed by the authors. Dispersion of low concentration of graphene c...
Abstract: Graphene is emerged as a highly sought after reinforcing filler for epoxy matrix in view of its superior electrical, mechanical and thermal properties. Dispersion of low concentration of graphene c...
TL;DR: In this paper, zinc oxide nanowires (ZnO NWs) were successfully functionalized with reduced graphene oxide (rGO) by successive ionic layer adsorption and reaction (SILAR) method on a glass substrate.
Abstract: Zinc oxide nanowires were deposited by successive ionic layer adsorption and reaction (SILAR) method on a glass substrate. Graphene oxide powders were electrochemically exfoliated from graphite. The presence of peaks at 20.42°, 22.69°, 25.61° and 43° in the XRD pattern confirms the formation of reduced graphene oxide. Raman peak ratio (I D /I G ) was found to be 1.051 for the synthesized powder and it confirms the formation of reduced graphene oxide. Finally, zinc oxide nanowires (ZnO NWs) were successfully functionalized with reduced graphene oxide (rGO). The basic characterization studies such as morphological, structural, and compositional analyses were carried out for rGO/ZnO NWs. It confirmed the formation of ZnO NWs and rGO functionalization over it. The sensing response of ZnO and rGO/ZnO NWs towards the ammonia vapour were studied at ambient temperature (32 °C). The obtained results revealed that the sensitivity and selectivity of the ZnO NWs were increased after functionalization. The adsorption mechanism was studied through FTIR and the corresponding results were discussed.