Graphene Composite Materials Research Articles

Electrochemically enhanced removal of perfluorinated compounds (PFCs) from aqueous solution by CNTs-graphene composite electrode

Electrochemical removal of environmentally persistent perfluorinated compounds (PFCs) from aqueous solution by Ti/activated carbon fiber (ACF), Ti/Ebonex/carbon nanotubes (CNTs), and CNTs-graphene composite electrode was investigated. The results indicated that the CNTs with 20wt% graphene (CNTs-20% graphene composite electrode) exhibited the optimal capacitive behavior and electrochemical property for the removal of perfluorooctanoate (PFOA) from aqueous solution. The removal ratio and sorption capacity of PFOA on CNTs-20% graphene electrode were 96.9% and 2421.7μgg−1 after 4h of electrosorption, respectively. The sorption equilibriums of PFOA and perfluorooctane sulfonate (PFOS) by CNTs-20% graphene electrode were approximately 4.0h and 2.0h, respectively. The electrosorption rates were 9.7 times (PFOA) and 12.7 times (PFOS) higher than those by powder CNTs-20% graphene composite material, respectively. The maximal sorption capacities of PFOA and PFOS on CNTs-20% graphene electrode were 491.9mgg−1 and 555.8mgg−1, respectively. The results indicated that the incorporation of graphene into CNTs could effectively enhance the electrochemical removal of PFCs from aqueous solution. These results provide an effective and alternative method to remove PFCs from wastewater with low energy consumption and mild experimental conditions.

Biomimetic sensor for sweet taste detection based on graphene composite materials

Sweet taste detection is of great significance in fields of disease prevention, food safety inspection, and drug regulation. In this study, a novel biomimetic sensor was constructed for sweet taste detection by compositing graphene oxide, hemin, and 3-aminophenylboronic acid (APBA). First, optimal fabrication of the sensor was investigated by comparing different composition proportions of graphene oxide and APBA functionalized hemin in saccharide measurements. Then, typical substances of natural sugars (i.e., glucose and fructose) and artificial sweeteners (i.e., saccharin and aspartame) were measured with the sensor through optical absorption spectroscopy. The spectra displayed apparent but different absorbance changes in the presence of those two kinds of saccharides, showing different sensing mechanisms of the biomimetic sensor for sugars and sweeteners like sweet receptors. Finally, dose-dependent and specific responses of the sensor were observed by comparing with other taste substances. The results suggested that the sensor can detect and distinguish natural sugars and artificial sweeteners in a biomimetic way. The research provided a low-cost, long-lifetime, and efficient approach for sweet taste detection, indicating its promising applications in fields such as food and beverage analysis.

A new route to synthesize polyaniline-grafted carboxyl-functionalized graphene composite materials with excellent electrochemical performance

A new route to synthesize polyaniline (PANI)-grafted carboxyl-functionalized graphene (PGCG) composite material is established. In this paper, PGCG is first prepared through a two-step carboxyl-functionalized process. PANI can be grafted and grown on the surface of graphene due to the covalent bonding existing between the carboxyl-functionalized graphene and polyaniline. This method cannot only improve the mechanical performance and adaptive performance of polyaniline effectively, but also reduce the production costs and environmental pollution during the synthetic process. Therefore, a green and industrial synthetic process is achieved. X-ray diffraction (XRD) patterns, X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared (FTIR) all confirm that composite materials have been prepared successfully. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate that the as-prepared PGCG has regular structure. Thermogravimetric analysis (TGA) indicates that the addition of graphene nanosheets can significantly improve the thermostability of PANI. Moreover, the as-prepared material exhibits superior electrochemical performance. As an electrode material for supercapacitors, PGCG possesses high specific capacitance of 158 F g−1 at a scan rate of 25 mV s−1 and 147 F g−1 at 50 mV s−1 in 1 M H2SO4. The Nyquist plot also confirms that the PGCG has low charge transfer resistance and good capacitive behavior. These great properties make PGCG a novel electrode material with potential applications in high-performance energy storage devices.

Electrodeposition of Sn-Ni Alloy As Anodes for Lithium-Ion Batteries

Sn can form Li22Sn4 reversibly with Li and gets more exploration as a kind of anode materials for lithium ion batteries. Li22Sn4 has a high theoretical capacity of 994 mAh/g, however, along with a problem that the huge volume change during the Li insertion and extraction and the material’s pulverization, leading to the short cycle ability. Using Ni as the inert matrix for Sn atom can control the volume change of tin material. In this paper, Sn-Ni alloys were electrodeposited on copper foils from aqueous electrolytes containing tin dichloride, nickel sulfate, sodium citrate, disodium EDTA and ascorbic acid. When the concentration rate of [Ni2+] to [Sn2+] was 3 to 1, Ni-Sn alloy particles were 400nm in diameter. Ni3Sn4 were the main structure of the alloy, which increased the cycle life of the lithium ion batteries. The reversible specific capacity of the Sn-Ni alloy electrode can reach to 654mAh/g. By the composite deposition of graphene, the sizes of Sn-Ni grains decreased and the properties of Sn-Ni alloy anodes improved. Magnetic fields also have effect on the micromorphologies and structures of Sn-Ni alloy, which cause the improvements of the performance of lithium ion batteries.

Self‐Assembled Flower–like ZnMoO4/Graphene Composite Materials as Anode in Lithium‐Ion Batteries

AbstractZnMoO4, carbon‐coated ZnMoO4 (ZnMoO4/C) and ZnMoO4/Graphene (ZnMoO4/G) composite grown on titanium substrate were synthesized by simple hydrothermal reaction and their lithium storage properties were investigated. The results show that, when compared with ZnMoO4 electrode, ZnMoO4/G composite exhibits higher specific capacity, better cycling performance and more outstanding rate capability than those of ZnMoO4/C composite, which are mainly attributed to the excellent conductivity of graphene and unique composite structure.

Tiny crystalline grain nanocrystal NiCo 2 O 4 /N-doped graphene composite for efficient oxygen reduction reaction

Oxygen reduction reaction (ORR) plays an important role in green energy conversion, although catalysts are necessary for overcoming its sluggish kinetic. Herein, a nanocrystal NiCo2O4/N-doped graphene composite material showing high ORR electrocatalytic activity is prepared. The resulting NiCo2O4/N-doped graphene composite (NiCo2O4-NG/C) combines the advantages of both component materials and shows enhanced ORR electrocatalytic activity (i.e., more positive peak potential and half-wave potential compared with NiCo2O4) while having higher diffusion-limited current density values (−5.7 mA cm−2, 1600 rpm), better tolerance to methanol, and improved stability than 20 wt% Pt/C. NiCo2O4 anchored on N-doped graphene are demonstrated to be nanocrystal with tiny crystalline grain (diameter < 5 nm) and result in large surface area, thereby allowing more active sites to be exposed. Moreover, the potential exposure of high-index planes may be also responsible for the observed high activity of these materials.

Preparation of Advanced CuO Nanowires/Functionalized Graphene Composite Anode Material for Lithium Ion Batteries.

The copper oxide (CuO) nanowires/functionalized graphene (f-graphene) composite material was successfully composed by a one-pot synthesis method. The f-graphene synthesized through the Birch reduction chemistry method was modified with functional group “–(CH2)5COOH”, and the CuO nanowires (NWs) were well dispersed in the f-graphene sheets. When used as anode materials in lithium-ion batteries, the composite exhibited good cyclic stability and decent specific capacity of 677 mA·h·g−1 after 50 cycles. CuO NWs can enhance the lithium-ion storage of the composites while the f-graphene effectively resists the volume expansion of the CuO NWs during the galvanostatic charge/discharge cyclic process, and provide a conductive paths for charge transportation. The good electrochemical performance of the synthesized CuO/f-graphene composite suggests great potential of the composite materials for lithium-ion batteries anodes.

Dielectric Characteristics and Microwave Absorption of Graphene Composite Materials.

Nowadays, many types of materials are elaborated for microwave absorption applications. Carbon-based nanoparticles belong to these types of materials. Among these, graphene presents some distinctive features for electromagnetic radiation absorption and thus microwave isolation applications. In this paper, the dielectric characteristics and microwave absorption properties of epoxy resin loaded with graphene particles are presented from 2 GHz to 18 GHz. The influence of various parameters such as particle size (3 µm, 6–8 µm, and 15 µm) and weight ratio (from 5% to 25%) are presented, studied, and discussed. The sample loaded with the smallest graphene size (3 µm) and the highest weight ratio (25%) exhibits high loss tangent (tanδ = 0.36) and a middle dielectric constant ε′ = 12–14 in the 8–10 GHz frequency range. As expected, this sample also provides the highest absorption level: from 5 dB/cm at 4 GHz to 16 dB/cm at 18 GHz.

Inside Back Cover: A Graphene Composite Material with Single Cobalt Active Sites: A Highly Efficient Counter Electrode for Dye‐Sensitized Solar Cells (Angew. Chem. Int. Ed. 23/2016)

Inside Back Cover: A Graphene Composite Material with Single Cobalt Active Sites: A Highly Efficient Counter Electrode for Dye‐Sensitized Solar Cells (Angew. Chem. Int. Ed. 23/2016)

A Graphene Composite Material with Single Cobalt Active Sites: A Highly Efficient Counter Electrode for Dye‐Sensitized Solar Cells

AbstractThe design of catalysts that are both highly active and stable is always challenging. Herein, we report that the incorporation of single metal active sites attached to the nitrogen atoms in the basal plane of graphene leads to composite materials with superior activity and stability when used as counter electrodes in dye‐sensitized solar cells (DSSCs). A series of composite materials based on different metals (Mn, Fe, Co, Ni, and Cu) were synthesized and characterized. Electrochemical measurements revealed that CoN4/GN is a highly active and stable counter electrode for the interconversion of the redox couple I−/I3−. DFT calculations revealed that the superior properties of CoN4/GN are due to the appropriate adsorption energy of iodine on the confined Co sites, leading to a good balance between adsorption and desorption processes. Its superior electrochemical performance was further confirmed by fabricating DSSCs with CoN4 /GN electrodes, which displayed a better power conversion efficiency than the Pt counterpart.

A Graphene Composite Material with Single Cobalt Active Sites: A Highly Efficient Counter Electrode for Dye-Sensitized Solar Cells.

The design of catalysts that are both highly active and stable is always challenging. Herein, we report that the incorporation of single metal active sites attached to the nitrogen atoms in the basal plane of graphene leads to composite materials with superior activity and stability when used as counter electrodes in dye-sensitized solar cells (DSSCs). A series of composite materials based on different metals (Mn, Fe, Co, Ni, and Cu) were synthesized and characterized. Electrochemical measurements revealed that CoN4 /GN is a highly active and stable counter electrode for the interconversion of the redox couple I(-) /I3 (-) . DFT calculations revealed that the superior properties of CoN4 /GN are due to the appropriate adsorption energy of iodine on the confined Co sites, leading to a good balance between adsorption and desorption processes. Its superior electrochemical performance was further confirmed by fabricating DSSCs with CoN4 /GN electrodes, which displayed a better power conversion efficiency than the Pt counterpart.

Thermal Conductivity on the Nanofluid of Graphene and Silver Nanoparticles Composite Material.

The composite material consisted of graphene (GN) and silver nanoparticles (AgNPs) has been essential topic in science and industry due to its unique thermal, electrical and antibacterial proper- ties. However, there are scarcity studies based on their thermal properties of nanofluids. Therefore, GN-AgNPs composite material was synthesized using facile and environment friendly method and further nanofluids were prepared by ultrasonication in this study. The morphological and structural investigations were carried out using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) as well as ultra violet (UV)-visible spectroscopy. Furthermore, thermal conductivity measurements were performed for as-prepared nanofluids. As a result of thermal conductivity study, GN-AgNPs composite material was considerably enhanced the thermal conductivity of base fluid (water) by to 6.59% for the nanofluid (0.2 wt% GN and 0.4 wt% AgNPs).

Supercapacitors Based on Three-Dimensional Hierarchical Graphene Aerogels with Periodic Macropores.

Graphene is an atomically thin, two-dimensional (2D) carbon material that offers a unique combination of low density, exceptional mechanical properties, thermal stability, large surface area, and excellent electrical conductivity. Recent progress has resulted in macro-assemblies of graphene, such as bulk graphene aerogels for a variety of applications. However, these three-dimensional (3D) graphenes exhibit physicochemical property attenuation compared to their 2D building blocks because of one-fold composition and tortuous, stochastic porous networks. These limitations can be offset by developing a graphene composite material with an engineered porous architecture. Here, we report the fabrication of 3D periodic graphene composite aerogel microlattices for supercapacitor applications, via a 3D printing technique known as direct-ink writing. The key factor in developing these novel aerogels is creating an extrudable graphene oxide-based composite ink and modifying the 3D printing method to accommodate aerogel processing. The 3D-printed graphene composite aerogel (3D-GCA) electrodes are lightweight, highly conductive, and exhibit excellent electrochemical properties. In particular, the supercapacitors using these 3D-GCA electrodes with thicknesses on the order of millimeters display exceptional capacitive retention (ca. 90% from 0.5 to 10 A·g(-1)) and power densities (>4 kW·kg(-1)) that equal or exceed those of reported devices made with electrodes 10-100 times thinner. This work provides an example of how 3D-printed materials, such as graphene aerogels, can significantly expand the design space for fabricating high-performance and fully integrable energy storage devices optimized for a broad range of applications.

High temperature superconducting materials based on Graphene / YBCO nanocomposite

New route synthesis of YBCO / graphene composite material is described in the present work. The oxide mixture and graphene were obtained separately and then mixed together by ball milling in the mass ratio graphene: YBCO = 1: 100. The oxide mixture was prepared by modified auto combustion reaction starting from stoichiometric amounts of yttrium acetate and barium and copper nitrates without any other organic compound addition. Graphene materials were prepared by reducing GO (i.e. oxidation of graphite powder by a modified Hummers method) with hidrazine sulphate. The final material resulted by applying the ball-milling method was investigated by XRD, SEM, Raman and HRTEM.

Electro-synthesized Ni coordination supermolecular-networks-coated exfoliated graphene composite materials for high-performance asymmetric supercapacitors

A Ni supermolecular-networks-coated exfoliated graphene composite is prepared via a facile “two-in-one” electrosynthesis and exhibits excellent supercapacitive performance.

Two polymolybdate-based complexes and their graphene composites with visible-light photo-responses

Two polymolybdate-based complexes with different band gaps show different visible-light photo-responses, and their graphene composite materials possess improved electrocatalytic activities for HER.

Influences of Lateral Size on the Properties of Graphene Based Materials and Poly(vinylbutyral)/Graphene Composite Materials

Influences of Lateral Size on the Properties of Graphene Based Materials and Poly(vinylbutyral)/Graphene Composite Materials

Ultrathin graphitic carbon nitride nanosheets and graphene composite material as high-performance PtRu catalyst support for methanol electro-oxidation

Graphitic carbon nitride (g-C3N4) has been demonstrated as an advanced support material for Pt nanoparticles (NPs) due to its excellent stability and abundant Lewis acid for anchoring metal NPs. However, its non-conductive nature and low surface areas still impede its application in electrochemical fields. Herein, a π–π stacking method is presented to prepare graphene/ultrathin g-C3N4 nanosheets composite support for PtRu catalyst. The weaknesses of g-C3N4 are greatly overcome by establishing a 2D layered structure. The significantly enhanced performance for this novel PtRu catalyst is ascribed to reasons as follows: the homogeneous dispersion of PtRu NPs on g-C3N4 nanosheets due to its abundant Lewis acid sites for anchoring PtRu NPs; the excellent mechanical resistance and stability of g-C3N4 nanosheets in acidic and oxidative environments; the increased electron conductivity of support by forming a layered structure and the strong metal-support interaction (SMSI) between metal NPs and g-C3N4 NS.

Synthesis of Metal Oxides/Graphene Nanocomposites for Applications in Lithium-Ion Battery

Over the past few years, lithium-ion battery has become a research spot due to its high voltage, high energy density and long cycle life. Traditional lithium-ion batteries employed graphite as anode material. However, graphite suffers from several shortcomings, such as low specific capacity, sluggish discharge current density, and relatively low cycle life. The discovery of graphene makes it possible to improve the performance of lithium-ion batteries significantly. Graphene with excellent electrochemical performance has attracted more and more attention. Graphene is a single layer of honeycomb sp2-hybridized carbon atoms with large surface area, high electrical conductivity and high thermal conductivity. In this report, we employed graphene and graphene-based composite material as anode materials for lithium-ion battery to improve their performance. Stannic oxide (SnO2), cobalt oxide (Co3O4), and vanadium pentoxide (V2O5) were synthesized respectively on graphene surfaces. The incorporation of metal oxides can further improve electron mobility of graphene and lithium-ion battery charge/ discharge stability. The performance of lithium-ion batteries was tested by charge-discharge experiments, and their charge-discharge current density, charge-discharge voltages, charging rate, and cycle stability were measured and discussed.

Facile large scale synthesis of Bi2S3 nano rods–graphene composite for photocatalytic photoelectrochemical and supercapacitor application

Bi2S3 nano rods–graphene (BG) composite material was synthesized by a simple one step precipitation method. The crystallanity, structural and morphological properties were studied by the X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy techniques. The photocatalytic activity of BG was evaluated by the photocatalytic degradation of malachite green dye (MG) aqueous solution under the visible light irradiation. The effect of graphene content on the photoelectrochemical property of Bi2S3 nano rods was also studied. The enhancement of photocurrent and photocatalytic properties of BG composite attributed to the synergistic effect between the Bi2S3 nano rods and graphene sheets which improves the charge separation efficiency in Bi2S3 nano rods. The supercapacitor behavior was studied using cyclic voltametry and galvanostatic charge discharge studies. The BG composite exhibits a maximum specific capacitance of 290Fg−1 at a current density of 1Ag−1. The present study may provide as a new approach in improving the performance of BG composite in supercapacitor, solar cells and photocatalytic applications.