Preparation and characterization of partially reduced graphene oxide aerogels doped with transition metal ions (original) (raw)
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Properties of a granulated nitrogen-doped graphene oxide aerogel
Journal of Non-Crystalline Solids, 2018
At first, a granulated aerogel of graphene oxide was obtained, which was later reduced by hydrazine vapour. The reduced aerogel was characterized through elemental analysis, infrared (IR) and Raman spectroscopy, electron paramagnetic resonance (EPR), thermogravimetric analyses (TGA), voltammetry, and X-ray photoelectron spectroscopy (XPS). Furthermore, the reduced sample was found to contain approximately 3 wt.% of nitrogen, which was present in the aerogel in three states corresponding to the photoelectron peaks N1s with binding energies of 399.5, 401.3, and 403.6 eV. In the electroreduction of oxygen, an appreciable catalytic effect was observed for the sample under study, which resulted from reducing the overvoltage of the reaction by~90 mV and changing the mechanism of reduction.
Synthesis and modification of reduced graphene oxide aerogels for biofuel cell applications
Materials Science-Poland, 2015
We have carried out the preparation of reduced graphene oxide aerogels using eco-friendly method that is based on the Hummers method of graphite oxidation without the use of NaNO3 that produces toxic gases. To obtain a porous 3D structure of reduced graphene oxide, we performed the hydrothermal reduction at elevated temperature. We also prepared the rGO aerogel/CNT composite using multiwalled carbon nanotubes as linkers. The rGO aerogels are promising materials as they possess good electrical conductivity (up to 100 S/m) and high surface area and porous structure (~500 m2/g). The main goal was to obtain the material for electrodes in enzymatic biofuel cells. Thus, the proper modification was performed using free radical functionalization. It was shown that in order to synthesize rGO aerogels modified with anthracene, the proper order of reactions needs to be provided. The morphology of anthracene modified electrodes was analyzed using scanning electron microscopy, which confirmed th...
A Facile and Green Synthesis of a MoO2-Reduced Graphene Oxide Aerogel for Energy Storage Devices
Materials, 2020
A simple, low cost, and “green” method of hydrothermal synthesis, based on the addition of l-ascorbic acid (l-AA) as a reducing agent, is presented in order to obtain reduced graphene oxide (rGO) and hybrid rGO-MoO2 aerogels for the fabrication of supercapacitors. The resulting high degree of chemical reduction of graphene oxide (GO), confirmed by X-Ray Photoelectron Spectroscopy (XPS) analysis, is shown to produce a better electrical double layer (EDL) capacitance, as shown by cyclic voltammetric (CV) measurements. Moreover, a good reduction yield of the carbonaceous 3D-scaffold seems to be achievable even when the precursor of molybdenum oxide is added to the pristine slurry in order to get the hybrid rGO-MoO2 compound. The pseudocapacitance contribution from the resulting embedded MoO2 microstructures, was then studied by means of CV and electrochemical impedance spectroscopy (EIS). The oxidation state of the molybdenum in the MoO2 particles embedded in the rGO aerogel was deeply...
Nanomaterials, 2019
Low-density three-dimensional (3D) N-doped graphene aerogels by a one-step solvothermal method in the presence of ethylenediamine (EDA) are reported. The gelation, formation, and properties of the aerogels were studied with solvothermal conditions, namely, operating temperature, time, graphene oxide (GO) concentration, and the GO/EDA w/w ratio. Two ranges of solvothermal conditions are employed: one involving an operating temperature below 100 °C and a conventional chemical reduction of GO with EDA at atmospheric pressure and a second one employing a higher temperature range up to 165 and a high pressure reduction with EDA. The results show that both solvothermal approaches allow for the fabrication of homogeneous N-doped 3D graphene aerogels with density values close to 10 mg cm−3. The measurements indicated that low values of GO concentration, temperature, and EDA are optimum for obtaining low-density 3D aerogels. N doping is improved with an EDA amount in lower temperature condit...
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Molecules, 2020
High-porosity monolithic composite aerogels of syndiotactic polystyrene (sPS) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) containing reduced graphene oxide (r-GO) were prepared and characterized. The composite aerogels obtained by supercritical carbon dioxide (scCO2) extraction of sPS/r-GO and PPO/r-GO gels were characterized by a fibrillar morphology, which ensured good handling properties. The polymer nanoporous crystalline phases obtained within the aerogels led to high surface areas with values up to 440 m2 g−1. The role of r-GO in aerogels was studied in terms of catalytic activity by exploring the oxidation capacity of composite PPO and sPS aerogels toward benzyl alcohol in diluted aqueous solutions. The results showed that, unlike sPS/r-GO aerogels, PPO/r-GO aerogels were capable of absorbing benzyl alcohol from the diluted solutions, and that oxidation of c.a. 50% of the sorbed benzyl alcohol molecules into benzoic acid occurred.
Reactive nanoenergetic graphene aerogel synthesized by one-step chemical reduction
Combustion and Flame, 2018
Adoption of nanoenergetic materials into large-scale applications is hindered by problems associated with scalability, particle aggregation, stability, and electrostatic discharge (ESD) sensitivity. We report a macroscale energetic graphene aerogel that simultaneously overcomes each of these problems while increasing the energy production and flame speed with respect to neat nanothermite sample. The aerogel is comprised of reduced graphene oxide (RGO), aluminum (Al) nanoparticles, and bismuth oxide (Bi 2 O 3) nanoparticles. Synthesis of the aerogel requires chemical reduction and gelling that preserves the reactivity of embedded fuel and oxide nanoparticles. A new gelation process is adopted in which ethylenediamine was added to a propylene carbonate dispersion to gel and reduce RGO while retaining material reactivity. The energetic aerogel enhances the heat of reaction to 967 J/g, which is 36% higher than that from loose Al/Bi 2 O 3 powder. A combustion speed of 960 ± 190 m/s under open ambient is measured for RGO/Al/Bi 2 O 3 gel, which is the highest value reported for an Al/Bi 2 O 3 system. Further, the underlying reduced graphene oxide scaffold reduces ESD sensitivity of the aerogel by three orders of magnitude.
Synthesis of Graphene Aerogel with High Electrical Conductivity
We report the synthesis of ultra-low-density threedimensional macroassemblies of graphene sheets that exhibit high electrical conductivities and large internal surface areas. These materials are prepared as monolithic solids from suspensions of single-layer graphene oxide in which organic sol-gel chemistry is used to cross-link the individual sheets. The resulting gels are supercritically dried and then thermally reduced to yield graphene aerogels with densities approaching 10 mg/cm 3 . In contrast to methods that utilize physical cross-links between GO, this approach provides covalent carbon bonding between the graphene sheets. These graphene aerogels exhibit an improvement in bulk electrical conductivity of more than 2 orders of magnitude (∼1 × 10 2 S/m) compared to graphene assemblies with physical cross-links alone (∼5 × 10 -1 S/m). The graphene aerogels also possess large surface areas (584 m 2 /g) and pore volumes (2.96 cm 3 /g), making these materials viable candidates for use in energy storage, catalysis, and sensing applications.
Reduced graphene oxide and inorganic nanoparticles composites – synthesis and characterization
Graphene – novel 2D material, which possesses variety of fascinating properties, can be considered as a convenient support material for the nanoparticles. In this work various methods of synthesis of reduced graphene oxide with metal or metal oxide nanoparticles will be presented. The hydrothermal approach for deposition of platinum, palladium and zirconium dioxide nanoparticles in ethylene glycol/water solution was applied. Here, platinum/ reduced graphene oxide (Pt/RGO), palladium/reduced graphene oxide (Pd/RGO) and zirconium dioxide/reduced graphene oxide (ZrO 2 /RGO) nanocomposites were prepared. Additionally, manganese dioxide/reduced graphene oxide nanocomposite (MnO 2 /RGO) was synthesized in an oleic-water interface. The obtained nanocomposites were investigated by transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), Raman spectroscopy and thermogravimetric analysis (TGA). The results shows that GO can be successfully used as a template for direct synthesis of metal or metal oxide nanoparticles on its surface with a homogenous distribution.
Synthesis and Characterization of Reduced Graphene Oxide
Advanced Materials Research, 2013
Reduced graphene oxide is an excellent candidate for various electronic devices such as high performance gas sensors. In this work Graphene oxide was prepared by oxidizing graphite to form graphite oxide. From XRD analysis the peak around 11.5o confirmed that the oxygen was intercalated into graphite. By using hydrazine hydrate, the epoxy group in graphite oxide was reduced then the solution of reduced graphite oxide (rGO) is exfoliated. Raman spectrum of rGO contains both G band (1580 cm-1), D band (1350 cm-1). The remarkable structural changes reveals that reduction of graphene oxide from the values of ID/IG ratio that increase from 0.727 (GO) to 1.414 (rGO). The exfoliated reduced graphite oxide solution is spin coated on to the SiO2/Si substrates.