in this research graphene oxide was synthesized by two methods. these methods were achieved by changing the improved hummers’ and modified hummers’ methods. structure of graphene oxide was characterized by scanning electron microscopy (sem) images, x-ray diffraction (xrd) patterns, raman spectroscopy and fourier transform infrared (ftir) spectra. according to sem image, the thickness of graphen...

We studied the local voltage drop in functionalized graphene sheets of subμm size under external bias conditions by Kelvin probe force microscopy. Using this noninvasive experimental approach, we measured ohmic current-voltage characteristics and an intrinsic conductivity of about 3.7 × 10(5) S/m corresponding to a sheet resistance of 2.7 kΩ/sq under ambient conditions for graphene produced via...

Carbon-supported precious metal catalysts are widely used in heterogeneous catalysis and electrocatalysis, and enhancement of catalyst dispersion and stability by controlling the interfacial structure is highly desired. Here we report a new method to deposit metal oxides and metal nanoparticles on graphene and form stable metal-metal oxide-graphene triple junctions for electrocatalysis applicat...

Synthesis of composite materials for an improved lithium-ion battery anode with the necessary attributes for a high performance anode prompted the examination of cobalt-manganese oxide because of its high capacity for lithium ions, and graphene oxide because of its high surface-tovolume ratio and high conductivity. Mixing these materials in a controlled manner is challenging at the nanoscale. T...

bending analysis of multilayer graphene sheets (mlgss) subjected to non-uniform shear and normal tractions is presented. the constitutive relations are considered to be non-classical based on nonlocal theory of elasticity. based on the differential transformation method, numerical illustrations are carried out for circular and annular geometries. the effects of nano scale parameter, radius of c...

The distribution of potential, electric field, and gradient of square of electric field was simulated via a finite element method for dielectrophoresis (DEP) assembly. Then reduced graphene oxide sheets (RGOS)- and graphene oxide sheets (GOS)-based electrical circuits were fabricated via DEP assembly. The mechanically exfoliated graphene sheets (MEGS)-based electrical circuit was also fabricate...

Optimized concentration of reduced graphene oxide (rGO) in the lube is one of the important factors for effective lubrication of solid body contacts. At sufficiently lower concentration, the lubrication is ineffective and friction/wear is dominated by base oil. In contrast, at sufficiently higher concentration, the rGO sheets aggregates in the oil and weak interlayer sliding characteristic of g...

A facile method to produce conformal coated reduced graphene oxide (rGO) on vertically aligned titanium oxide (TiO2) nanotubes three dimensional (3D) arrays (NTAs) is demonstrated for enhanced field emission display applications. These engineered nano arrays exhibit efficient electron field emission properties such as high field emission current density (80 mA/cm(2)), low turn-on field (1.0 V/μ...

The abrasion is a significant issue, especially in machining of rigid steels. A functional and suitable approach for enhancing the heat transfer from machining area is using an intermediate fluid with higher heat transfer potential instead of common fluids. The objective of this experimental study is to discuss production, stability and thermal conductivity examination of water/graphene oxide n...

in this study, an efficient and facile technique for preparing graphene oxide in suspension and powder forms was presented based on a modification on hummers' method followed by an additional ultrasonic process. the method involved the provision of graphene oxide from graphite by reaction of potassium permanganate and sulfuric acid with stabilizing the medium complex. furthermore, this stu...