Showing papers on "Graphene oxide paper published in 2017"
TL;DR: Here, cationic control of the interlayer spacing of graphene oxide membranes with ångström precision is demonstrated using K+, Na+, Ca2+, Li+ or Mg2+ ions, suggesting that other ions could be used to produce a wider range of interlayer spacings.
Abstract: Graphene oxide membranes-partially oxidized, stacked sheets of graphene-can provide ultrathin, high-flux and energy-efficient membranes for precise ionic and molecular sieving in aqueous solution. These materials have shown potential in a variety of applications, including water desalination and purification, gas and ion separation, biosensors, proton conductors, lithium-based batteries and super-capacitors. Unlike the pores of carbon nanotube membranes, which have fixed sizes, the pores of graphene oxide membranes-that is, the interlayer spacing between graphene oxide sheets (a sheet is a single flake inside the membrane)-are of variable size. Furthermore, it is difficult to reduce the interlayer spacing sufficiently to exclude small ions and to maintain this spacing against the tendency of graphene oxide membranes to swell when immersed in aqueous solution. These challenges hinder the potential ion filtration applications of graphene oxide membranes. Here we demonstrate cationic control of the interlayer spacing of graphene oxide membranes with angstrom precision using K+, Na+, Ca2+, Li+ or Mg2+ ions. Moreover, membrane spacings controlled by one type of cation can efficiently and selectively exclude other cations that have larger hydrated volumes. First-principles calculations and ultraviolet absorption spectroscopy reveal that the location of the most stable cation adsorption is where oxide groups and aromatic rings coexist. Previous density functional theory computations show that other cations (Fe2+, Co2+, Cu2+, Cd2+, Cr2+ and Pb2+) should have a much stronger cation-π interaction with the graphene sheet than Na+ has, suggesting that other ions could be used to produce a wider range of interlayer spacings.
1,082 citations
10 Jan 2017
TL;DR: In this article, a modified Hummers method was used to synthesize reduced graphite oxide (rGO), which was then used as a precursor for graphene synthesis by thermal reduction processes.
Abstract: Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one of the oldest techniques yet it is one of the most suitable methods for the formation of bulk graphene. Graphene can be obtained in the form of reduced Graphite oxide, sometimes also referred as Graphene oxide. The effectiveness of this oxidation process can be evaluated by the magnitude of carbon/oxygen ratio of the obtained graphene. Here, graphene oxide (GO) was prepared by oxidizing the purified natural flake graphite (NFG) by a modified Hummers method. The attempts have been made to synthesize GO having few layers by using a modified Hummers method where the amount of NaNO3 has been decreased, and the amount of KMnO4 is increased. The reaction has been performed in a 9:1 (by volume) mixture of H2SO4/H3PO4. This modification is successful in increasing the reaction yield and reducing the toxic gas evolution while using a varied proportion of KMnO4 and H2SO4 as those required by Hummers method. A new component of K2S2O8 has been introduced to the reaction system to maintain the pH value. Reduced graphene oxide (rGO) was thereafter extracted by thermal modification of GO. Here, GO has been used as a precursor for graphene synthesis by thermal reduction processes. The results of FTIR and Raman spectroscopy analysis show that the NFG when oxidized by strong oxidants like KMnO4 and NaNO3, introduced oxygen atoms into the graphite layers and formed bonds like C=O, C-H, COOH and C-O-C with the carbon atoms in the graphite layers. The structure and morphology of both GO and rGO were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).
665 citations
TL;DR: In this article, the growth of a single-crystal graphene film of 5 × 50 cm2 dimension with > 99% ultra-highly oriented grains was achieved by using a temperature gradient-driven annealing technique.
Abstract: A foundation of the modern technology that uses single-crystal silicon has been the growth of high-quality single-crystal Si ingots with diameters up to 12 inches or larger. For many applications of graphene, large-area high-quality (ideally of single-crystal) material will be enabling. Since the first growth on copper foil a decade ago, inch-sized single-crystal graphene has been achieved. We present here the growth, in 20 min, of a graphene film of (5 × 50) cm2 dimension with >99% ultra-highly oriented grains. This growth was achieved by: (1) synthesis of metre-sized single-crystal Cu(1 1 1) foil as substrate; (2) epitaxial growth of graphene islands on the Cu(1 1 1) surface; (3) seamless merging of such graphene islands into a graphene film with high single crystallinity and (4) the ultrafast growth of graphene film. These achievements were realized by a temperature-gradient-driven annealing technique to produce single-crystal Cu(1 1 1) from industrial polycrystalline Cu foil and the marvellous effects of a continuous oxygen supply from an adjacent oxide. The as-synthesized graphene film, with very few misoriented grains (if any), has a mobility up to ∼23,000 cm2 V−1 s−1 at 4 K and room temperature sheet resistance of ∼230 Ω/□. It is very likely that this approach can be scaled up to achieve exceptionally large and high-quality graphene films with single crystallinity, and thus realize various industrial-level applications at a low cost.
411 citations
TL;DR: Graphene film with large-area multifunctional GFs can be easily integrated into high-power flexible devices for highly efficient thermal management and render GF superflexible with a high fracture elongation up to 16%, enabling it more than 6000 cycles of ultimate folding.
Abstract: Electrical devices generate heat at work. The heat should be transferred away immediately by a thermal manager to keep proper functions, especially for high-frequency apparatuses. Besides high thermal conductivity (K), the thermal manager material requires good foldability for the next generation flexible electronics. Unfortunately, metals have satisfactory ductility but inferior K (≤429 W m−1 K−1), and highly thermal-conductive nonmetallic materials are generally brittle. Therefore, fabricating a foldable macroscopic material with a prominent K is still under challenge. This study solves the problem by folding atomic thin graphene into microfolds. The debris-free giant graphene sheets endow graphene film (GF) with a high K of 1940 ± 113 W m−1 K−1. Simultaneously, the microfolds render GF superflexible with a high fracture elongation up to 16%, enabling it more than 6000 cycles of ultimate folding. The large-area multifunctional GFs can be easily integrated into high-power flexible devices for highly efficient thermal management.
382 citations
TL;DR: In this paper, the authors used poly(2-butylaniline) (P2BA) as a dispersing agent to achieve stable dispersion of graphene in organic solvents via non-covalent π-π interactions between P2BA and graphene.
336 citations
TL;DR: In this article, a mixture of concentrated H2SO4/H3PO4 and ascorbic acid was used to produce reduced graphene oxide, which was then used for graphite powder synthesis.
Abstract: In this work, graphene oxide was synthesized by treating graphite powder with KMnO4 and a mixture of concentrated H2SO4/H3PO4 and reduced with ascorbic acid to produce reduced graphene oxide. The e...
314 citations
TL;DR: In this article, the Fe 3 O 4 /nitrogen-doped graphene nanosheets were fabricated by solvothermal method as synergistic microwave absorbers, and the results indicated that the hybrid was ideal candidate to be used as a microwave absorber with antioxidation, light weight, high efficiency and broad frequency bandwidth.
310 citations
TL;DR: Graphene nanoribbons on highly porous 3D graphene foam as the binder-free cathode for flexible Al-ion batteries exhibit low charge voltage, high capacity, excellent cycling ability, and fast charging and slow discharging performance.
Abstract: Graphene nanoribbons on highly porous 3D graphene foam as the binder-free cathode for flexible Al-ion batteries exhibit low charge voltage, high capacity, excellent cycling ability (even after 10 000 cycles there is no capacity decay), and fast charging and slow discharging performance (the battery can be fully charged in 80 s and discharged in more than 3100 s).
307 citations
TL;DR: Two-dimensional hexagonal boron nitride (h-BN) has similar lattice structure to graphene and has a lattice mismatch with graphene of less than 1.7%. At the same time, h-BN has an atomic level of flat surface, B atoms and N atoms saturated into the bond, which was considered the highest among the insulating substrates as discussed by the authors.
289 citations
TL;DR: Experimental results and molecular dynamic simulations revealed that the presence of deoxycholate enhances NaCl rejection in these graphene-based membranes, and these novel hybrid-layered membranes exhibit better chlorine resistance than pure graphene oxide membranes.
Abstract: Carbon nanomaterials are robust and possess fascinating properties useful for separation technology applications, but their scalability and high salt rejection when in a strong cross flow for long periods of time remain challenging. Here, we present a graphene-based membrane that is prepared using a simple and environmentally friendly method by spray coating an aqueous dispersion of graphene oxide/few-layered graphene/deoxycholate. The membranes were robust enough to withstand strong cross-flow shear for a prolonged period (120 h) while maintaining NaCl rejection near 85% and 96% for an anionic dye. Experimental results and molecular dynamic simulations revealed that the presence of deoxycholate enhances NaCl rejection in these graphene-based membranes. In addition, these novel hybrid-layered membranes exhibit better chlorine resistance than pure graphene oxide membranes. The desalination performance and aggressive shear and chlorine resistance of these scalable graphene-based membranes are promising for use in practical water separation applications. Scalable graphene-based membranes reject more than 80% NaCl under aggressive shear for more than 20 h and exhibit chlorine resistance.
280 citations
TL;DR: The one-step direct synthesis of 2D Mo2 C-on-graphene film by molten copper-catalyzed chemical vapor deposition (CVD) is reported, showing a much lower onset voltage for hydrogen evolution reactions as compared to Mo 2 C-only electrodes.
Abstract: As a new member of the MXene group, 2D Mo2 C has attracted considerable interest due to its potential application as electrodes for energy storage and catalysis. The large-area synthesis of Mo2 C film is needed for such applications. Here, the one-step direct synthesis of 2D Mo2 C-on-graphene film by molten copper-catalyzed chemical vapor deposition (CVD) is reported. High-quality and uniform Mo2 C film in the centimeter range can be grown on graphene using a Mo-Cu alloy catalyst. Within the vertical heterostructure, graphene acts as a diffusion barrier to the phase-segregated Mo and allows nanometer-thin Mo2 C to be grown. Graphene-templated growth of Mo2 C produces well-faceted, large-sized single crystals with low defect density, as confirmed by scanning transmission electron microscopy (STEM) measurements. Due to its more efficient graphene-mediated charge-transfer kinetics, the as-grown Mo2 C-on-graphene heterostructure shows a much lower onset voltage for hydrogen evolution reactions as compared to Mo2 C-only electrodes.
TL;DR: It turns out that composite coating with 0.5 wt % graphene additive exhibits superior anticorrosive ability and is proved by the identification of corrosion products and the scanning vibrating electrode technique.
Abstract: Dispersion of graphene in water and its incorporation into waterborne resin have been rarely researched and hardly achieved owing to its hydrophobicity. Furthermore, it has largely been reported that graphene with impermeability contributed to the improved anticorrosion property. Here, we show that highly concentrated graphene aqueous solution up to 5 mg/mL can be obtained by synthesizing hydrophilic polypyrrole (PPy) nanocolloids as intercalators and ultrasonic vibration. On the basis of π–π interaction between PPy and graphene, stacked graphene sheets are exfoliated to the thickness of three to five layers without increasing defects. The corrosion performance of coatings without and with PPy and graphene is obtained by potential and impedance measurements, Tafel curves, and fitted pore resistance by immersing in a 3.5 wt % NaCl solution. It turns out that composite coating with 0.5 wt % graphene additive exhibits superior anticorrosive ability. The mechanism of intercalated graphene-based coating is int...
TL;DR: An N-superdoped 3D graphene network structure with an N-doping level up to 15.8 at% for high-performance supercapacitor is designed and synthesized, in which the graphene foam with high conductivity acts as skeleton and nested with N- superdoped reduced graphene oxide arogels.
Abstract: An N-superdoped 3D graphene network structure with an N-doping level up to 15.8 at% for high-performance supercapacitor is designed and synthesized, in which the graphene foam with high conductivity acts as skeleton and nested with N-superdoped reduced graphene oxide arogels. This material shows a highly conductive interconnected 3D porous structure (3.33 S cm−1), large surface area (583 m2 g−1), low internal resistance (0.4 Ω), good wettability, and a great number of active sites. Because of the multiple synergistic effects of these features, the supercapacitors based on this material show a remarkably excellent electrochemical behavior with a high specific capacitance (of up to 380, 332, and 245 F g−1 in alkaline, acidic, and neutral electrolytes measured in three-electrode configuration, respectively, 297 F g−1 in alkaline electrolytes measured in two-electrode configuration), good rate capability, excellent cycling stability (93.5% retention after 4600 cycles), and low internal resistance (0.4 Ω), resulting in high power density with proper high energy density.
TL;DR: It is demonstrated that the selectivity/flux trade-off can be broken by self-assembly of SLGO via simple deposition rate control and thus may greatly facilitate the development of ultrathin GO membranes for high flux, high selectivity water purification.
Abstract: Single-layer graphene oxide (SLGO) is emerging as a new-generation membrane material for high-flux, high-selectivity water purification, owing to its favorable two-dimensional morphology that allows facile fabrication of ultrathin membranes with subnanometer interlayer channels. However, reliable and precise molecular sieving performance still necessarily depends on thick graphene oxide (GO) deposition that usually leads to low water flux. This trade-off between selectivity and flux significantly impedes the development of ultrathin GO membranes. In this work, we demonstrate that the selectivity/flux trade-off can be broken by self-assembly of SLGO via simple deposition rate control. We find GO membranes, prepared by slow deposition of SLGO flakes, exhibit considerably improved salt rejection, while counterintuitively having 2.5–4 times higher water flux than that of membranes prepared by fast deposition. This finding has extensive implications of designing/tuning interlayer nanostructure of ultrathin GO ...
TL;DR: In this paper, a large volume, high-concentration, plane-defect-free, few-layer graphene dispersion is fast produced from graphite at high yield through ball milling.
Abstract: Due to low density, extremely high electrical and thermal conductivities, graphene has great potential to construct lightweight thermal conductive paper for high-power electric devices. However, the remarkable properties of graphene are on a molecular level and difficult to achieve when processed into macroscopic paper. Here, an effective route to construct ultrahigh conductive graphene paper is developed. First, large-volume, high-concentration, plane-defect-free, few-layer graphene dispersion is fast produced from graphite at high yield through ball milling. The exfoliated graphene dispersion is further processed into graphene paper through fast filtration, thermal treatment, and mechanical compression. The electrical and thermal conductivities of the resultant graphene paper are as high as 2231 S cm−1 and 1529 W m−1 K−1, superior to previously reported graphene papers. Structural analyses confirm that the ultrahigh conductivities are attributed to high quality of graphene sheets, their compact ordered stacking, and large graphitic crystalline domain size, which improve electron and phonon transport within basal plane of graphene sheet and between graphene sheets.
16 Oct 2017
TL;DR: In this paper, the authors compared the properties of reduced graphene oxide (RGO) and graphite with graphite using Fourier Transform Infra-Red (FTIR) analysis and showed the presence of abundant oxygen-containing functional groups in GO as compared to graphite.
Abstract: Graphene oxide (GO) and reduced graphene oxide (RGO) are known to have superior properties for various applications. This work compares the properties of GO and RGO with graphite. GO was prepared by using Improved Hummer’s method whereas the produced GO was subjected to chemical reduction with the use of hydrazine hydrate. Graphite, GO and RGO had different morphologies, quality, functionalized groups, UV-Vis absorption peaks and crystallinity. With the removal of oxygen-containing functional group during reduction for RGO, the quality of samples was decreased due to higher intensity of D band than G band was seen in Raman results. In addition, platelet-like surface can be observed on the surface of graphite as compared to GO and RGO where wrinkled and layered flakes, and crumpled thin sheets were observed on GO and RGO surface respectively. Fourier Transform Infra-Red (FTIR) analysis showed the presence of abundant oxygen-containing functional groups in GO as compared to RGO and graphite. The characteris...
TL;DR: Highly optimized nickel cobalt mixed oxide has been derived from zeolite imidazole frameworks, which has given an extremely high and unprecedented specific capacitance and shows a significant improvement in the cyclic stability with 81% capacitance retention after 5000 cycles.
Abstract: Highly optimized nickel cobalt mixed oxide has been derived from zeolite imidazole frameworks. While the pure cobalt oxide gives only 178.7 F g-1 as the specific capacitance at a current density of 1 A g-1 , the optimized Ni:Co 1:1 has given an extremely high and unprecedented specific capacitance of 1931 F g-1 at a current density of 1 A g-1 , with a capacitance retention of 69.5% after 5000 cycles in a three electrode test. This optimized Ni:Co 1:1 mixed oxide is further used to make a composite of nickel cobalt mixed oxide/graphene 3D hydrogel for enhancing the electrochemical performance by virtue of a continuous and porous graphene conductive network. The electrode made from GNi:Co 1:1 successfully achieves an even higher specific capacitance of 2870.8 F g-1 at 1 A g-1 and also shows a significant improvement in the cyclic stability with 81% capacitance retention after 5000 cycles. An asymmetric supercapacitor is also assembled using a pure graphene 3D hydrogel as the negative electrode and the GNi:Co 1:1 as the positive electrode. With a potential window of 1.5 V and binder free electrodes, the capacitor gives a high specific energy density of 50.2 Wh kg-1 at a high power density of 750 W kg-1 .
TL;DR: LGO has a much lower density of defects than GO prepared using the conventional Hummers' method and can be readily transformed into graphene by chemical reduction, and the unique advantages of using LGO sheets as a performance enhancer are discussed.
Abstract: Graphene oxide (GO) can be considered as one of the most visible outcomes of graphene research in terms of large scale production and commercialization prospects. Although GO can be easily prepared by oxidation-exfoliation of graphite in agitated solutions, the size of these sheets is generally limited due to fragmentation along fault lines during chemical oxidation and exfoliation in agitated solutions. In this account, we discuss recent strategies which have been developed for the preparation of large sized graphene oxide (LGO) sheets with lateral sizes >10 μm, using chemically expanded graphite as the starting material. LGO has a much lower density of defects than GO prepared using the conventional Hummers' method and can be readily transformed into graphene by chemical reduction. In addition, the unique advantages of using LGO sheets as a performance enhancer are discussed. Finally, this review also discusses recent advances in the chemical and electrochemical reduction of graphene oxide.
TL;DR: To enable excellent strain-dependent performance of transparent graphene conductors, graphene nanoscrolls in between stacked graphene layers, referred to as multilayer graphene/graphene scrolls (MGGs) were created.
Abstract: Two-dimensional materials, such as graphene, are attractive for both conventional semiconductor applications and nascent applications in flexible electronics. However, the high tensile strength of graphene results in fracturing at low strain, making it challenging to take advantage of its extraordinary electronic properties in stretchable electronics. To enable excellent strain-dependent performance of transparent graphene conductors, we created graphene nanoscrolls in between stacked graphene layers, referred to as multilayer graphene/graphene scrolls (MGGs). Under strain, some scrolls bridged the fragmented domains of graphene to maintain a percolating network that enabled excellent conductivity at high strains. Trilayer MGGs supported on elastomers retained 65% of their original conductance at 100% strain, which is perpendicular to the direction of current flow, whereas trilayer films of graphene without nanoscrolls retained only 25% of their starting conductance. A stretchable all-carbon transistor fabricated using MGGs as electrodes exhibited a transmittance of >90% and retained 60% of its original current output at 120% strain (parallel to the direction of charge transport). These highly stretchable and transparent all-carbon transistors could enable sophisticated stretchable optoelectronics.
TL;DR: In this article, a bio-inspired nanolaminated architecture was used to enhance the efficiencies of two-dimensional (2D) graphene in mechanical strengthening and electrical conducting by aligning graphene to maximize performance for required loading and carrier transporting conditions.
TL;DR: In this article, the rational design and in situ synthesis of hierarchical porous nanocomposite sheets of nitrogen-doped graphene oxide (NGO) and nickel sulfide (Ni7S6) derived from a hybrid of a well-known nickel-based metal-organic framework (NiMOF-74) using thiourea as a sulfur source are reported.
Abstract: Engineering of controlled hybrid nanocomposites creates one of the most exciting applications in the fields of energy materials and environmental science. The rational design and in situ synthesis of hierarchical porous nanocomposite sheets of nitrogen-doped graphene oxide (NGO) and nickel sulfide (Ni7S6) derived from a hybrid of a well-known nickel-based metal-organic framework (NiMOF-74) using thiourea as a sulfur source are reported here. The nanoporous NGO/MOF composite is prepared through a solvothermal process in which Ni(II) metal centers of the MOF structure are chelated with nitrogen and oxygen functional groups of NGO. NGO/Ni7S6 exhibits bifunctional activity, capable of catalyzing both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with excellent stability in alkaline electrolytes, due to its high surface area, high pore volume, and tailored reaction interface enabling the availability of active nickel sites, mass transport, and gas release. Depending on the nitrogen doping level, the properties of graphene oxide can be tuned toward, e.g., enhanced stability of the composite compared to commonly used RuO2 under OER conditions. Hence, this work opens the door for the development of effective OER/HER electrocatalysts based on hierarchical porous graphene oxide composites with metal chalcogenides, which may replace expensive commercial catalysts such as RuO2 and IrO2.
TL;DR: SnS2 nanoparticles anchored onto reduced graphene oxide are produced via a chemical route and demonstrate an impressive capacity of 350 mA h g-1, exceeding the capacity of graphite.
TL;DR: The graphene-coated contact lens would provide a healthcare and bionic platform for wearable technologies in the future and reduce the exposure to EM waves and dehydration.
Abstract: Recently, smart contact lenses with electronic circuits have been proposed for various sensor and display applications where the use of flexible and biologically stable electrode materials is essential. Graphene is an atomically thin carbon material with a two-dimensional hexagonal lattice that shows outstanding electrical and mechanical properties as well as excellent biocompatibility. In addition, graphene is capable of protecting eyes from electromagnectic (EM) waves that may cause eye diseases such as cataracts. Here, we report a graphene-based highly conducting contact lens platform that reduces the exposure to EM waves and dehydration. The sheet resistance of the graphene on the contact lens is as low as 593 Ω/sq (±9.3%), which persists in an wet environment. The EM wave shielding function of the graphene-coated contact lens was tested on egg whites exposed to strong EM waves inside a microwave oven. The results show that the EM energy is absorbed by graphene and dissipated in the form of thermal ra...
TL;DR: In this article, large-sized graphene sheets and doping strategy were employed to fabricate lightweight and flexible graphene paper with exceptional electromagnetic interference (EMI) shielding performance, which resulted in higher electrical conductivity and strength of graphene paper.
TL;DR: It is shown that graphene paper supercapacitor electrodes containing aramid nanofibers as guest materials exhibit extraordinarily high tensile strength and excellent electrochemical stability, nearly rivaling those of graphene-based pseudocapacitors.
Abstract: Structural energy and power systems offer both mechanical and electrochemical performance in a single multifunctional platform. These are of growing interest because they potentially offer reduction in mass and/or volume for aircraft, satellites, and ground transportation. To this end, flexible graphene-based supercapacitors have attracted much attention due to their extraordinary mechanical and electrical properties, yet they suffer from poor strength. This problem may be exacerbated with the inclusion of functional guest materials, often yielding strengths of <15 MPa. Here, we show that graphene paper supercapacitor electrodes containing aramid nanofibers as guest materials exhibit extraordinarily high tensile strength (100.6 MPa) and excellent electrochemical stability. This is achieved by extensive hydrogen bonding and π–π interactions between the graphene sheets and aramid nanofibers. The trade-off between capacitance and mechanical properties is evaluated as a function of aramid nanofiber loading, w...
TL;DR: It is shown that homogeneous stable dispersions of single-layer graphene (SLG) in water can be obtained by mixing graphenide (negatively charged graphene) solutions in tetrahydrofuran with degassed water and evaporating the organic solvent.
Abstract: Dispersing graphite in water to obtain true (single-layer) graphene in bulk quantity in a liquid has been an unreachable
goal for materials scientists in the past decade. Similarly, a diagnostic tool to identify solubilized graphene in situ has been
long awaited. Here we show that homogeneous stable dispersions of single-layer graphene (SLG) in water can be obtained
by mixing graphenide (negatively charged graphene) solutions in tetrahydrofuran with degassed water and evaporating
the organic solvent. In situ Raman spectroscopy of these aqueous dispersions shows all the expected characteristics of
SLG. Transmission electron and atomic force microscopies on deposits confirm the single-layer character. The resulting
additive-free stable water dispersions contain 400 m2 l–1 of developed graphene surface. Films prepared from these
dispersions exhibit a conductivity of up to 32 kS m–1.
TL;DR: The present bifunctional graphene paper possesses high durability against bending cycles over 500 times and wash time over 1500 min, suggesting its great potential in wearable PTM.
Abstract: Freestanding, flexible/foldable, and wearable bifuctional ultrathin graphene paper for heating and cooling is fabricated as an active material in personal thermal management (PTM) The promising electrical conductivity grants the superior Joule heating for extra warmth of 42 °C using a low supply voltage around 32 V Besides, based on its high out-of-plane thermal conductivity, the graphene paper provides passive cooling via thermal transmission from the human body to the environment within 7 s The cooling effect of graphene paper is superior compared with that of the normal cotton fiber, and this advantage will become more prominent with the increased thickness difference The present bifunctional graphene paper possesses high durability against bending cycles over 500 times and wash time over 1500 min, suggesting its great potential in wearable PTM
TL;DR: It is demonstrated that hybrid metal carbide MXene/reduced graphene oxide nanosheets could be a promising cathode host material for lithium-sulfur batteries.
Abstract: Three-dimensional metal carbide MXene/reduced graphene oxide hybrid nanosheets are prepared and applied as a cathode host material for lithium–sulfur batteries. The composite cathodes are obtained through a facile and effective two-step liquid-phase impregnation method. Owing to the unique 3 D layer structure and functional 2 D surfaces of MXene and reduced graphene oxide nanosheets for effective trapping of sulfur and lithium polysulfides, the MXene/reduced graphene oxide/sulfur composite cathodes deliver a high initial capacity of 1144.2 mAh g−1 at 0.5 C and a high level of capacity retention of 878.4 mAh g−1 after 300 cycles. It is demonstrated that hybrid metal carbide MXene/reduced graphene oxide nanosheets could be a promising cathode host material for lithium–sulfur batteries.
TL;DR: In this paper, a novel technique of preparing Zn2GeO4 nanostructures has been developed by using chemical precipitation method of GeCl4 as a Ge precursor and acacen as a capping agent.
TL;DR: A facile and versatile approach to bond graphene foam (GF) with polydimethylsiloxane (PDMS) is proposed, and the corresponding composite with considerable improvement in TC and insulativity is fabricated.
Abstract: To meet the increasing demands for effective heat management of electronic devices, a graphene-based polymeric composite is considered to be one of the candidate materials owing to the ultrahigh thermal conductivity (TC) of graphene. However, poor graphene dispersion, low quality of exfoliated graphene, and strong phonon scattering at the graphene/matrix interface restrict the heat dissipation ability of graphene-filled composites. Here, a facile and versatile approach to bond graphene foam (GF) with polydimethylsiloxane (PDMS) is proposed, and the corresponding composite with considerable improvement in TC and insulativity is fabricated. First, three-dimensional GF was coated with polydopamine (PDA) via π–π stack and functional groups from PDA reacted with 3-aminopropyltriethoxysilane (APTS). Then, the modified GF was compressed (c-GF) to enhance density and infiltrated with PDMS to get the c-GF/PDA/APTS/PDMS composite. As a result, these processes endow the composite with high TC of in-plane 28.77 W m–1...