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Graphene oxide (GO) and reduced graphene oxide (RGO) presents great potential applications in various fields due to their extraordinary properties. However, to synthesize GO and RGO environmental friendly and inexpensive still is a big challenge for large scale production. Although chemical synthesis method is the easiest, low cost, and large amount production compares to the other methods but there are some disadvantages using chemical such as toxicity, hazardous and corrosive which are harmful to the environment and human health. Therefore, it is recommended to using green reduction agent to replace the chemical agent. This paper presents a summary and discussion of the green reduction of GO to RGO using Oolong Tea extract. It also reviews the characterization of GO and RGO using of X-ray diffiaction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet- visible spectroscopy (UV-Vis). [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is known has some unique properties for various applications. GO is the oxidation form of graphene. It is synthesized from graphite through chemical oxidation. The structure of GO is different with graphite and graphene where the plane of the GO is attached with oxygen functional groups. In this research, GO was prepared by using improved Hummers' method from natural graphite powder. In addition, the effects of different reaction time of 24 hours, 48 hours, 72 hours and 96 hours on the yields of GO were studied. Results indicated that different samples of GO possessed different morphologies, attachment of functionalized groups, crystallinity and absorption peaks in Ultraviolet Visible (UV-Vis) spectroscopy. GO was characterized by using a Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and UV-Vis. SEM result showed platelet-like surface that appeared on the surface of GO (48 hours) as compared with GO (72 hours) where wavy wrinkled and layered-flakes, and crumpled structures were seen on GO (96 hours) surface respectively. In FTIR results, the existence of higher amount of abundant oxygen-containing functional groups was confirmed in GO (96 hours) as compared with GO (24 hours) due to the longer oxidation time. Furthermore, the absorption peak of GO was noticed at around 230 nm and the intensity of peak was increased with reaction time. By comparing these results, the oxidation of graphite to form GO can be determined accurately. Therefore, this study is a great beneficial to provide more understanding for many researchers about how to control the quality and amount of GO by varying reaction times for various applications. [ABSTRACT FROM AUTHOR]

Researchers studied graphene oxide (GO) and reduced graphene oxide (rGO), to explore its usefulness in different fields and applications. To produce rGO using conventional method at low-cost and environmental-friendly is a huge challenge because it involves harmful and hazardous chemicals such as hydrazine hydrate. Therefore, scientists proposed several green reducing agents as an alternative method to produce a same product. This research presents an outline and discussion of green synthesis of rGO using green tea extract as the reducing agents by manipulating their reaction time. Besides, it also gives an overview on the characterization of GO and rGO by analysing them using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy-dispersive X-ray spectroscopy (EDX), Fourier Transmission Infrared (FTIR) and Ultraviolet-visible Spectroscopy (UV-Vis). XRD spectra has proven the GO and rGO were successfully synthesised by exhibiting the peak at 9.75 nm and 25.42 nm respectively. In SEM images, wrinkled and flaky structures were observed in both GO and rGO while the EDX showed the composition of them. Moreover, the FTIR analysis suggested that the amount of oxygen functional groups in GO were decreased when it was reduced to rGO whereas the UV-Vis spectra proved the presence of absorption peak of GO (230 nm) and rGO (280 nm) accurately at different locations. Thus, the objectives of this research were achieved, and this green method can be a substitution to lower down the rely on chemical substances. [ABSTRACT FROM AUTHOR]

Magnetite nanoparticles were synthesized through co-precipitation method, in which surfactant such as polyvinylpyrrolidone (PVP) and sodium dodecyl benzene sulfonate (SDBS) were applied as stabilizing agent. Various techniques were employed to characterize the synthesized magnetite nanoparticles. Magnetite nanoparticles with spinel structure are successfully synthesized and confirmed by X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results proved that surface of magnetite nanoparticles were successfully coated with PVP and SDBS. From the transmission electron microscope (TEM), it showed that surfactant coated magnetite nanoparticles possess smaller particle size than that of bare magnetite nanoparticles. In comparison with SDBS, PVP has a better capping efficiency and the PVP coated magnetite nanoparticles have an average particle size of 10.8 nm. In addition, surfactant coated magnetite nanoparticles also exhibited lower value of saturation magnetization (Ms). Lower value of Ms might be attributed to the small sized nanoparticles. All magnetite nanoparticles synthesized with and without surfactant showed superparamagnetic behaviour. Bare and surfactant coated magnetite nanoparticles have been utilized as a demulsifier for crude oil in water emulsion. Those nanoparticles that produced using SDBS (ED=87%) showed higher efficiency than that of PVP coated (ED=80%) and bare magnetite nanoparticles (ED=85%) in demulsification tests. [ABSTRACT FROM AUTHOR]

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 characteristic peaks at 26.62°, 9.03° and 24.10° for graphite, GO and RGO, respectively, can be detected from X-Ray diffraction (XRD). Furthermore, the reduction also caused red shift at 279nm from 238nm, as obtained from ultraviolet visible (UV-Vis) analysis. The results proved that GO was successfully oxidized from graphite whereas RGO was effectively reduced from GO. [ABSTRACT FROM AUTHOR]

This work describes the effect of hydrazine hydrate on the formation of the raspberry-like morphology of the cobalt nanomaterials in a polyol route. In the synthesis, the molar ratio of N2H4 to Co2+ was varied from 2.5 to 10. At the beginning with low molar ratio, spherical microspheres were formed. When the molar ratio was increased to 5 and above, final morphology of the cobalt nanomaterials became raspberry-like. This might be attributed to the absorption of the hydrazine complex of cobalt nanoparticles at certain facets during their growth stage and later self-assembled into the raspberry shaped microparticles. The plausible formation mechanism were proposed. [ABSTRACT FROM AUTHOR]

To produce thin-walled plastic items, injection molding process is one of the most widely used application tools. However, to set optimal process parameters is difficult as it may cause to produce faulty items on injected mold like shrinkage. This study aims at to determine such an optimum injection molding process parameters which can reduce the fault of shrinkage on a plastic cell phone cover items. Currently used setting of machines process produced shrinkage and mis-specified length and with dimensions below the limit. Thus, for identification of optimum process parameters, maintaining closer targeted length and width setting magnitudes with minimal variations, more experiments are needed. The mold temperature, injection pressure and screw rotation speed are used as process parameters in this research. For optimal molding process parameters the Response Surface Methods (RSM) is applied. The major contributing factors influencing the responses were identified from analysis of variance (ANOVA) technique. Through verification runs it was found that the shrinkage defect can be minimized with the optimal setting found by RSM. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of the mesoporous silica-supported gold (Au@mSiO2) nanoparticles compatibilized with the outer shelled superhydrophobic fluorous (F) "tails" was described. The concept of fluorous biphasic separation was applied in the recycling of the synthesized fluorous material during hydroamination reactions of various alkynes. In the presence of perfluoromethylcyclohexane and heptane as a biphasic liquid system, the F-Au@mSiO2 was found to be a highly active catalyst for hydroamination of various alkynes with anilines, and a near quantitative yield for an imine product and produced a relatively minimal formation of a corresponding hydrolyzed ketone by-product. If perfluoromethylcyclohexane and heptane was used as a biphasic solvent, hydroamination at a lower reaction temperature can also be realized leading to an improved recyclability and conversion. [ABSTRACT FROM AUTHOR]