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1.
《Ceramics International》2019,45(11):13894-13902
Tailoring transition-metal oxide nanoparticles with two-dimensional carbon has become a favorite way to improve their electrochemical performance. In this study, a composite of reduced graphene oxide was anchored by Co3O4 nanocubes and easily prepared with the assistance of polydopamine (PDA), using a combination of hydrothermal reaction and pyrolysis (Co3O4@PDA-rGO). Polydopamine, which possesses abundant catechol and amine groups, could be easily grafted onto graphene oxide to reduce the aggregation of graphene particles. Furthermore, PDA provided active sites, i.e., catechol and amine groups, which coordinated with Co2+, enabling enrichment of metal ions on the surface of graphene. After the pyrolysis of Co2+-containing PDA-grafted graphene at 400 °C, the Co2+ ions were converted into Co3O4 nanocubes, while the PDA carbonized to form N-doped porous carbon on the surface of graphene. The resulting product, Co3O4@PDA-rGO, demonstrated extraordinary supercapacitive behavior with good cycling stability owing to its unique porous structure as well as the intimate contact between Co3O4 and the carbon matrix.  相似文献   

2.
The current paper focuses on synthesizing a high-efficiency microwave absorber via incorporating the nanofillers of graphene oxide-polyaniline (GO-PANI), barium-strontium titanate (BST), and soft-hard ferrite within the polyester matrix. The nanocomposite magnets of (Ba0.5Sr0.5Fe12O19)1-x hard/(CoFe2O4)x soft (x = 0.2, 0.5, and 0.8) were prepared using sol-gel auto-combustion method. The GO-PANI and BST were successfully synthesized by in situ polymerization and improved polymerization, respectively. The phase structure, chemical structure, morphology, and microwave absorption properties of the synthesized nanocomposites were characterized by X-ray diffractometer (XRD), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM), vector network analyzer (VNA) techniques, respectively. The results showed that the synergistic effects of the combination of dielectric (BST), conductive (GO-PANI), and magnetic materials (hard-soft ferrites) provided the reflection loss values of less than ?20 dB (>99% absorption) in the X-band region. The minimum reflection loss of ?35 dB (>99.99% absorption) was obtained by the optimal formulation including (Ba0.5Sr0.5Fe12O19)0.2 (CoFe2O4)0.8, and the weight ratio of 1: 2 for both BST/soft-hard ferrite and hard-soft ferrite + BST/GO-PANI with the thickness of 1 mm. According to the results, the thickness factor plays a key role in improving the impedance matching. Consequently, the proposed nanocomposite can be employed as a novel kind of microwave absorbers with good impendence matching and high absorption.  相似文献   

3.
CuO/graphene composite as anode materials for lithium-ion batteries   总被引:2,自引:0,他引:2  
CuO/graphene composite is synthesized from CuO and graphene oxide sheets following reduced by hydrazine vapor. As the electrode material for lithium-ion batteries, CuO nanoparticles with sizes of about 30 nm homogeneously locate on graphene sheets, and act as spacers to effectively prevent the agglomeration of graphene sheets, keeping their high active surface. In turn, the graphene sheets with good electrical conductivity server as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during discharge/charge process. The synergetic effect is beneficial for the electrochemical performances of CuO/graphene composite, such as improved initial coulombic efficiency (68.7%) and reversible capacity of 583.5 mAh g−1 with 75.5% retention of the reversible capacity after 50 cycles.  相似文献   

4.
In this letter, a double active layer (Zr:SiO x /C:SiO x ) resistive switching memory device with outstanding performance is presented. Through current fitting, hopping conduction mechanism is found in both high-resistance state (HRS) and low-resistance state (LRS) of double active layer RRAM devices. By analyzing Raman and FTIR spectra, we observed that graphene oxide exists in C:SiO x layer. Compared with single Zr:SiO x layer structure, Zr:SiO x /C:SiO x structure has superior performance, including low operating current, improved uniformity in both set and reset processes, and satisfactory endurance characteristics, all of which are attributed to the double-layer structure and the existence of graphene oxide flakes formed by the sputter process.  相似文献   

5.
《Ceramics International》2023,49(4):5997-6005
Due to the escalating demand for electronic dependability and defense security, there has been a surge in research into broadband and lightweight microwave absorbers. Porous composites that are lightweight and plentiful in interfaces have the potential to be high-performance absorbers due to their ability to attenuate waves in a balanced manner and match impedance. “Using a solvothermal technique we generated FeSe2/rGO composites with a porous topology. By varying the weight of rGO, the electromagnetic properties of FeSe2/rGO composites may be finely tuned. Impedance matching and attenuation capability are both improved as a direct result of the porous structure and the appropriate electromagnetic parameters. FeSe2/rGO composites benefit from the tunable composition, porous structure, and strong synergistic effect between FeSe2 and rGO sheets and display outstanding microwave absorption performance with an ultrabroad bandwidth approaching 5.2 GHz with a thin thickness of 1.6 mm which covers 75% of the studied frequency range. At the same thickness, a significant reflection loss of ?43.7 dB is attained. This work not only enables the tuning of electromagnetic parameters but also expands the use of high-performance microwave absorption devices. Remarkable microwave absorption ability, of the porous composites FeSe2/rGO can be utilized as a high-performance microwave absorber.”  相似文献   

6.
The Co0.33Ni0.33Mn0.33Fe2O4/graphene nanocomposite for electromagnetic wave absorption was successfully synthesized from metal chlorides solutions and graphite powder by a simple and rapid microwave-assisted polyol method via anchoring the Co0.33Ni0.33Mn0.33Fe2O4 nanoparticles on the layered graphene sheets. The Fe3+, Co2+, Ni2+ and Mn2+ ions in the solutions were attracted by graphene oxide obtained from graphite and converted to the precursors Fe(OH)3, Co(OH)2, Ni(OH)2, and Mn(OH)2 under slightly alkaline conditions. After the transformations of the precursors to Co-Ni-Mn ferrites and conversion of graphene oxide to graphene under microwave irradiation at 170?°C in just 25?min, the Co0.33Ni0.33Mn0.33Fe2O4/graphene nanocomposite was prepared. The composition and structure of the nanocomposite were characterized by X-ray diffraction (XRD), inductive coupled plasma emission spectroscopy (ICP), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), transmission electron microscopy (TEM), etc. It was found that with the filling ratio of only 20?wt% and the thickness of 2.3?mm, the nanocomposite showed an ultra-wide effective absorption bandwidth (less than ?10?dB) of 8.48?GHz (from 9.52 to 18.00?GHz) with the minimum reflection loss of ??24.29?dB. Compared to pure graphene sheets, Co0.33Ni0.33Mn0.33Fe2O4 nanoparticles and the counterparts reported in literature, the nanocomposite exhibited much better electromagnetic wave absorption, mainly attributed to strong wave attenuation, as a result of synergistic effects of dielectric loss, conductive loss and magnetic loss, and to good impedance matching. In view of its thin thickness, light weight and outstanding electromagnetic wave absorption property, the nanocomposite could be used as a very promising electromagnetic wave absorber.  相似文献   

7.
《Ceramics International》2022,48(7):9579-9594
In the field of orthopaedic implants, post-surgery infections and biocompatibility are the most challenging obstacles. Sustained and controlled antibiotic release is a key factor in novel drug delivery systems. A novel drug delivery system combined with vaterite microsphere, graphite oxide (GO), reduced graphene oxide (rGO) incorporated in a polycaprolactone (PCL) matrix on TiO2 nanotube coated Ti (TNT-Ti) is established. Anodization was employed to develop TiO2 nanotubular arrays on Ti. Ciprofloxacin hydrochloride (CPF–HCl) loaded vaterite microspheres were synthesized by in situ precipitation method. Deposition of vaterite/PCL, vaterite-GO/PCL and vaterite-rGO/PCL composite coating on TNT-Ti was carried out by dip coating method. The composite coatings were characterized for their phase content, morphological features and functional groups. Among the three types of composite coatings, vaterite-rGO/PCL composite coating is found to be capable of encapsulating CPF-HCl to a level of 75.14 μg. The drug release profile of CPF-HCl from the vaterite-rGO/PCL composite coating exhibits a controlled release amounting to only 35.02 % of release at the end of 120 h. The vaterite-rGO/PCL composite coating exhibits a low dissolution rate and possesses adequate bioactivity in HBSS and SBF solutions at 37 °C for 14 and 10 days, respectively. The in situ loaded CPF-HCL drug on vaterite microspheres, PCL polymer matrix and GO/rGO nanofillers does not affect the cytocompatibility and all the composite coatings supported cell viability and proliferation. The ability of vaterite-rGO/PCL composite coating to provide a slow and steady release of antibiotics with sufficient bioactivity and biocompatibility at the tissue implant interface makes it a promising for osteomyelitis infection of bone tissue implant materials.  相似文献   

8.
The rising production of produced water from oilfields had been proven to bring detrimental environmental effects. In this study, an efficient, recyclable, and environmental-friendly reduced graphene oxide immobilized κ-Carrageenan hydrogel composite(κCa GO) was fabricated as an alternative sorbent for crude oil-in-water demulsification. Polyethyleneimine(PEI) was employed to form a stable hydrogel composite. The conditions for the immobilization of graphene oxide(GO) on PEI-modified κ-Carrageenan(κC) beads were optimized appropriately. An immobilization yield of 77% was attained at 2% PEI, 2 h immobilization activation time, and p H6.5. Moreover, the synthesized κCa GO is capable of demulsification with an average demulsification efficiency of 70%. It was found that the demulsification efficiency increases with salinity and κCa GO dosage, and it deteriorates under alkaline condition. These phenomena can be attributed to the interfacial interactions between κCa GO and the emulsion. Furthermore, the κCa GO can be recycled to use for up to six cycles without significant leaching and degradation. As such, the synthesized κCa GO could be further developed as a potential sorbent substitute for the separation of crude oil from produced water.  相似文献   

9.
Graphene nanosheet (GNS)/Co3O4 composite has been rapidly synthesized by microwave-assisted method. Field emission scanning electron microscopy and transmission electron microscopy observation reveals the homogeneous distribution of Co3O4 nanoparticles (3-5 nm in size) on graphene sheets. Electrochemical properties are characterized by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. A maximum specific capacitance of 243.2 F g−1 has been obtained at a scan rate of 10 mV s−1 in 6 M KOH aqueous solution for GNS/Co3O4 composite. Furthermore, the composite exhibits excellent long cycle life along with ∼95.6% specific capacitance retained after 2000 cycle tests.  相似文献   

10.
Graphene is considered a promising active electrode material due to a large surface area, high electronic conductivity, and chemical and mechanical stabilities for supercapacitor (SC) applications. However, the current bottleneck is the fabrication of restacking-inhibited graphene on an electrode level which otherwise loses the capability to achieve the aforementioned properties. Herein, we demonstrate the synthesis of restacking-inhibited nitrogen (N)-incorporated mesoporous graphene for high energy SCs. The melamine-formaldehyde acts as a restacking inhibitor by forming a bonding with reduced graphene oxide (RGO) through a condensation reaction and as an N precursor to be decomposed to create open pores and N sources upon heat treatment. The d-spacing increases up to 0.352 nm and the surface area is as high as 698 m2 g?1 with high mesoporosity, confirming restacking inhibition by N incorporation decomposed by melamine-formaldehyde. The restacking-inhibited RGO-based SC cells in organic electrolyte show the specific capacitance of 25.8 F g?1, the energy density of 21.8 kW kg?1 and 85% of capacitance retention for 5000 cycles, which are better than those of pristine RGO-based cells. These improved SC performances are attributed to the fast ion transport through a mesoporous channel in crumpled structure and the doping effect of N incorporation. This work provides a simple yet effective chemical approach to fabricate restacking-inhibited RGO electrodes for improved SC performances.  相似文献   

11.
《Ceramics International》2021,47(18):25505-25513
Herein, (Co0.5Ni0.5)Cr0.3Fe1.7O4/graphene oxide nanocomposites were fabricated by ultrasonication technique, using pure spinel ferrite and graphene oxide synthesized by sol-gel method and modified Hummers' method, respectively. The effect of graphene incorporation with ferrite nanoparticles was studied by X-ray diffraction (XRD), electrical and dielectric measurements. XRD analysis revealed the spinel phase for the ferrite sample and confirmed the formation of graphene oxide. The crystallite size was found in the range of 3743 nm and the porosity increased with the increase in the concentration of graphene oxide in the composites. The DC electrical resistivity of spinel ferrite was found equal to 3.83×109 Ω.cm and it substantially decreased with the increase in the percentage of graphene oxide at room temperature. The real and imaginary part of relative permittivity followed the Maxwell-Wagner type of interfacial polarization. AC conductivity confirmed the conduction by hopping mechanism and increased on increasing the GO content. The coupling of magnetic ferrite with graphene oxide tunes the magneto-electrical properties for potential applications at high frequencies.  相似文献   

12.
Mn3O4 nanoparticles (NPs) are decorated with reduced graphene oxide nanosheets (rGO-Mn3O4) through a facile and eco-friendly hydrothermal method. The as-synthesized composite was characterized by XRD, SEM, TEM and Raman spectroscopy. The electrochemical properties of (rGO-Mn3O4) nanocomposite were studied as electrode materials for supercapacitors. The rGO-Mn3O4 nanocomposite exhibit high specific capacitance of 457 Fg?1 at 1.0 A/g in 1 M Na2SO4 aqueous electrolyte. The rGO-Mn3O4 exhibits good capacitance retention by achieving 91.6% of its initial capacitance after 5000 cycles. The excellent electrochemical performance is attributed to the increased electrode conductivity in the presence of graphene network.  相似文献   

13.
With the aim to obtain microwave absorbers simultaneously possessing broad absorption bandwidth, strong absorption intensity and thin matching thickness, nitrogen-doped reduced graphene oxide decorated by cerium oxide particles (NRGO/CeO2) hybrid nanocomposite was prepared through a hydrothermal and calcination two-step route. Results of micromorphology analysis showed that numerous hexagonal CeO2 nanoparticles were evenly anchored on the crumpled surfaces of NRGO. Moreover, both nitrogen doping and hybridization with RGO could notably strengthen the microwave absorption capacity of CeO2. Remarkably, the NRGO/CeO2 hybrid nanocomposite exhibited the minimum reflection loss of ?57.2 dB at 13.4 GHz (Ku band) under a matching thickness of 1.66 mm and maximum absorption bandwidth of 4.6 GHz (from 13.2 to 17.8 GHz) at an ultrathin thickness of only 1.5 mm. Meanwhile, the hybrid nanocomposites displayed strong absorption intensity (≤-20 dB, 99% absorption) in almost the whole measured thicknesses range. Furthermore, the relationship between absorption intensity and filler loadings was uncovered. The potential microwave absorption mechanisms were further revealed. Therefore, this work opened a novel idea for designing RGO-based hybrid nanocomposites as high-performance microwave absorbers.  相似文献   

14.
《Ceramics International》2019,45(11):14376-14383
Zero-dimensional cadmium sulfide (CdS) nanoparticles with small size (∼50 nm) were grafted on the two-dimensional reduced graphene oxide (RGO) nanosheet via a facile hydrothermal method without any surfactant to synthesize CdS@RGO nanocomposites in this paper. The structural analysis confirms the strong attachment and interaction between CdS and RGO in CdS@RGO photocatalyst, which leads to a higher photocatalytic efficiency (95.3%) with superior anti-corrosion stability (almost no change of efficiency over three repeated experiments) to that of pure CdS in visible light. The unique hybrid nanostructure of CdS@RGO can effectively prevent the self-corrosion of CdS and facilitate the separation of electron-hole pairs. Consequently, these outstanding photocatalytic performances of CdS@RGO endow it with a promising prospect for the degradation of organic pollutants and this work can be extended to other graphene-based inorganic semiconductor composites.  相似文献   

15.
The role of graphene oxide (GO) as an oil-based additive on the tribological behavior of Ti/Al-DLC films and its dependence on GO concentration were systematically investigated. The results revealed that, compared to the additive-free case, the system with a GO concentration of 0.003 wt% achieved remarkable friction reduction and wear resistance, which were decreased by 38.4% and 23.5%, respectively. This is attributed to the synergistic effect of tribo-induced graphitization and the adsorption of GO on the worn surface. However, when the GO concentration was further increased, it induced the clumping of the GO additive, causing increased friction coefficient and severe abrasive wear of the worn surface.  相似文献   

16.
《Ceramics International》2021,47(18):26082-26091
Ultralight graphene/phenolic resin composite aerogels (GPFs) were prepared through the chemical reduction and self-assembly of graphene oxide (GO) in water-soluble phenolic resin, followed by a freeze-drying process; carbonized foams (GPFs(T)) were obtained by the subsequent heat treatment of GPFs at a relatively low temperature (500–700 °C). Although GPFs do not show the qualified reflection loss value of below −10dB, GPFs(T) achieve the greatly enhanced electromagnetic-wave absorbing performance. Specifically, the minimum reflection loss value of GPF1 (500) reaches −22.7 dB at 14.4 GHz with the absorber thickness of 2.0 mm and the effective absorption bandwidth is up to 5.4 GHz (12.4–17.8 GHz). The evolution of electromagnetic-wave absorbing properties from GPFs to GPFs(T) at different temperatures related with different graphene content is explored. GPFs(T) are expected to exhibit high thermal stability and excellent corrosion resistance property, and especially still maintain ultralight nature (e.g the density of GPF1 (500) is only 24.3 mg/cm3). Most importantly, little graphene (as low as 7.5 wt% of GO addition for GPF1(T)) in GPFs(T) guarantees the facile formation of three-dimension (3D) skeleton network and greatly cut downs the carbonization temperature of phenolic resin to achieve the required electromagnetic-wave energy losing ability. The present work provides an effective method to fabricate an ultralight material with exceptional performances including the good electromagnetic-wave absorbing property and the high stability.  相似文献   

17.
Currently, SnC2O4 is considered as one of the most promising anode materials for high-energy lithium-ion batteries (LIBs) because its charge capacity is higher than that of metal oxides. Herein, a facile microwave-assisted solvothermal method was employed to obtain SnC2O4/GO composites within only 30?min, which is time-efficient. The amount of SnC2O4 was increased to 95.3?wt% to improve the capacity of the composite. Pure SnC2O4 with a high specific surface area of 19.6?m2 g?1 without any other tin compound was used for fabrication. The SnC2O4/GO composite exhibited excellent electrochemical performance, with reversible discharge/charge capacity of 657/659?mA?h?g?1 after 100 cycles at 0.2?A?g?1. Furthermore, at high current densities of 1.0 and 2.0?A?g?1, the SnC2O4/GO composite anode exhibited high reversible discharge/charge capacities of 553/552 and 418/414?mA?h?g?1, respectively, after 200 cycles at room temperature. These improvements were likely obtained because SnC2O4 was well composited with graphene, which not only offered rapid electron transfer but also released the tension produced by the volumetric effect during repeated lithiation/delithiation. Cyclic voltammetry (CV) was also performed to further study the electrochemical reactions of SnC2O4/GO. The facile microwave-assisted solvothermal method used herein is considered as a highly efficient method to fabricate metal oxalate/graphene composites for use as anode materials in LIBs.  相似文献   

18.
Carbon nanotubes/graphene composites have superior mechanical, electrical and electrochemistry properties with carbon nanotubes as a hydrophobicity boosting agent. Their extraordinary hydrophobic performance is highly suitable for electrode applications in lithium ion batteries and supercapacitors which often employ organic electrolytes. Also the hydrophobic features enable the oil enrichment for the crude oil separation from seawater. The ever reported synthesis routes towards such a composite either involve complicated multi-step reactions, e.g., chemical vapor depositions, or lead to insufficient extrusion of carbon nanotubes in the chemical reductions of graphene oxide, e.g., fully embedding between the compact graphene oxide sheets. As a consequence, the formation of standalone carbon nanotubes over graphene sheets remains of high interests. Herein we use the facile flash light irradiation method to induce the reduction of graphene oxides in the presence of carbon nanotubes. Photographs, micrographs, X-ray diffraction, infrared spectroscopy and thermogravimetric analysis all indicate that graphene oxides has been reduced. And the contact angle tests confirm the excellent hydrophobic performances of the synthesized carbon nanotube/reduced graphene oxide composite films. This one-step treatment represents a straightforward and high efficiency way for the reduction of carbon nanotubes/graphene oxides composites.
  相似文献   

19.
A duplex coating composed of electrophoretic deposited graphene oxide (GO) inner-layer and electrodeposited GO/Mg substituted hydroxyapatite (MH) outer-layer was prepared on carbon/carbon composites (CC). The morphology and microstructure of GO-GO/MH coating were researched by Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The bonding strength between GO-GO/MH coating and CC substrate was investigated by shear test. The in-vitro bioactivity of GO-GO/MH coating was analyzed by simulated body fluid (SBF) immersion test. The results demonstrated that electrophoretic deposited GO inner-layer was successfully introduced on CC and could serve as an interlayer between CC and following electrodeposited GO/MH outer-layer. GO/MH outer-layer presented a flake morphology with 150–250?nm in thickness and 1.5–2.5?µm in width, exhibiting porous three-dimensional networks structure uniformly. The shear test showed that the bonding strength between the duplex coating and CC reached 7.4?MPa, which was 80.49% higher than that of single-layered MH coating without GO. The duplex coating could induce the formation of flocculent and chapped apatite after SBF immersion, which demonstrated the in-vitro bioactivity of the duplex coating. These results suggested that GO-GO/MH coating might be a promising candidate in the field of biomaterials, especially for implant coatings.  相似文献   

20.
《Ceramics International》2017,43(5):4475-4482
Porous carbon spheres (PCSs) with high surface area were fabricated by the reaction of D-Glucose monohydrate precursor with sodium molybdate dihydrate (Na2MoO4·2H2O) via a facile hydrothermal method followed by carbonization and aqueous ammonia solution (NH3·H2O) treatment. The as-prepared PCSs exhibit a highly developed porous structure with a large specific surface area and show an excellent electrochemical performance as anode material of sodium-ion batteries (SIBs). A reversible capacity of 249.9 mA h g−1 after 50 cycles at a current density of 50 mA g−1 and a long cycling life at a high current density of 500 mA g−1 are achieved. The excellent cycling performance and high capacity make the PCSs a promising candidate for long cycling SIBs.  相似文献   

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