Formation Of Graphene Nanosheets Research Articles

Facile and Benign Method to Produce Large Scale Graphene Nano Sheets

The large scale production of Graphene Nano Sheets (GNS) has fascinated many researchers. GNS was produced base on a sustainable raw material namely coconut fruit. Coconut fruit was converted directly to be GNS with ethanol assisted. Then, it was characterized by XRD and TEM. Interestingly, XRD data show the C(002) peak is broad and weak appear, indicating GNS was formed. This data is also consistent with TEM data. Therefore, the formation of GNS may definitely be affected by the immersing process of coconut fruit by ethanol. Base on this research, the large scale GNS may be produced with the facile and benign method.

Against Overcharring Design of Flame-Retardant Electromagnetic Absorbing Composites with Graphene Nanosheets and Manganese Oxides in Modified Epoxy Resin

Flame-retardant composites for fireproof application of electromagnetic (EM) absorption are produced from the dispersion and formation of graphene nanosheets (GNS) and exfoliated manganese oxides (EMOs) in diphenyl amidophosphate (DAP)-modified epoxy resin. The DAP-modified composite can be a friendly type of high-performance EM absorbing material in practical application, because of its halogen-free merits and high reflection loss in EM absorbance. An overcharring phenomenon is discovered in the retardants with multicomponents embedded in a resin matrix. The flame retardancy of the DAP composite is exhibited from thermogravimetric analysis (TGA). Kinetics analysis presents the difference of composites before and after modification in thermal decomposition. Improvement of multicomponents wrapped system can result from dissociation of P–O bonds during the course of burning. A cone calorimeter is utilized to evaluate the combustion performance to learn about the retardancy of composites. Guarding against overcharring between components, synergistic effect of flame retardancy can be achieved in improving the performance of resin-based absorbers.

Role of Peroxide Ions in Formation of Graphene Nanosheets by Electrochemical Exfoliation of Graphite

This study demonstrates a facile, mild and environmentally-friendly sustainable (soft processing) approach for the efficient electrochemical exfoliation of graphite using a sodium hydroxide/hydrogen peroxide/water (NaOH/H2O2/H2O) system that can produce high-quality, anodic few-layer graphene nanosheets in 95% yield at ambient reaction conditions. The control experiment conducted using NaOH/H2O revealed the crucial role of H2O2 in the exfoliation of graphite. A possible exfoliation mechanism is proposed. The reaction of H2O2 with hydroxyl ions (HO−) leads to the formation of highly nucleophilic peroxide ions (O22−), which play a crucial role in the exfoliation of graphite via electrochemical-potential-assisted intercalation and strong expansion of graphite sheets.

Controlled synthesis of graphene sheets with tunable sizes by hydrothermal cutting

We report a hydrothermal method that directly reduces graphene oxide (GO) into graphene nanosheets (GNs) with different sizes. In the presence of NaOH and hydrazine, the hydrothermal reaction at 80 °C resulted in the formation of GNs with a lateral size of ~1 μm but the size of GNs decreased to ~300 and ~100 nm upon increasing the reaction temperature to 150 and 200 °C, respectively. The morphology of the resulting GNs was observed by atomic force microscopy and transmission electron microscopy. The thickness of GNs is basically <3 nm, indicates the GNs stack together in a few-layer manner. XRD, XPS, FTIR, and Raman spectroscopy were used to characterize the structural changes before and after reduction. The results suggested that the defect stability in GO and reduced GNs could be responsible for the temperature dependence of the size of reduced GNs. A hydrothermal method is proposed to simultaneously reduce and cut graphene oxide into graphene sheets with different sizes in a controlled manner, in which the reaction temperature as a critical parameter is used to control the size of resulting graphene sheets.