Papers by Keyword: Intercalation

Abstract: Sensors based on clay-modified electrode have been studied extensively. They have been made from different intercalation compounds to determine both organic and inorganic species. Various analytical techniques have been applied for clay-modified electrodes. In this work, we used ZnS-montmorillonite as a sensor to construct an electrochemical electrode or potentiometric electrode by mixing ZnS-montmorillonite with graphite, polytetrafluoroethylene (PTFE) and carboxymethylcellulose (CMC) in an appropriate ratio. It was found that, the electrode gave best response to sulfide ion compared with other ions. The graph plotted between potential in mV against log[S2-] gave slope near 29.5 due to Nernst equation. The pH studied showed that the potential was almost constant at pH 4-11 and pH 4-9 in 0.01 M and 0.001 M of S2- solutions, respectively. This implied that the sensor could be used at a wide range of pH. The electrode also gave good precision.

Abstract: Au nanoparticles supported on MgAl-LDHs has been synthesized by coprecipitation method, gold colloid routs as well as intercalation and assembly method respectively. The influence of the above different preparation methods on the activity of the gold catalysts for CO oxidation was investigated, and the phase and gold particle size distribution of the catalysts were analyzed by XRD and TEM respectively. The results show that 100% conversion of CO on the fresh prepared gold catalysts synthesized by gold colloid routs and intercalation assembly method can be achieved at room temperature when the catalysts were activated at 473K for 2h in the air. The gold particle size distribution was range from 2nm to 7nm.

Abstract: Using first-principle calculations employing density functional theory (DFT) the stabilityof a (3, 3) carbon nanotube (CNT) intercalated with lithium atoms, with respect to their position aswell as Li/C ratio, is studied. On varying the distance of a lithium atom from the axis of the CNT in theradial direction, through the center of a graphitic hexagon, minimum of energy of the system occursat a distance of 3.8 °A from the axis. Keeping the distance of the lithium atom from the tube axis fixedat 3.8 °A, intercalation energy ( E) was calculated while the number of lithium atoms is varied fromone (Li1C12, −0.511 eV) to six (Li6C12, −0.615 eV). It is found that the intercalation becomes morefavorable with the increase in number of lithium atoms intercalated and increase in the symmetryof the intercalated system. The maximum intercalation energy difference between successive lithiumatom additions lay within 0.1 eV.

Abstract: The synthesis and characterisation of various organic-inorganic nanohybrids are reported in this contribution. The host material was Ca₃Fe-LDH prepared by the co-precipitation method. E-cinnamate, E-4-nitrocinnamate or E-2,5-difluorocinnamate anions were the guests. Successful intercalation occurred through the introduction of the guest anion into the interlayer region of the host materials with the dehydration-rehydration method. The obtained nanohybrids were studied by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray fluorescence (EDX) coupled to the SEM instrument and infrared spectroscopy (IR). These methods were used on one hand to prove that intercalation was successful and for the characterisation of the substances on the other. Molecular modelling was used for visualising the possible spatial arrangement of the organic anions.

Abstract: Using the preliminary research of the polymer properties, the different between the physical and chemical properties of new polymer-clays nanometer composites and clay have been studied. Different polymers are used to evaluate experiment. Based on a large number of lab experiments, the changes of rheological property and API filtration property of polymer-clay drilling fluids nanometer composites are studied. The results show that clay particles could become smaller and the composites drilling fluid have the role of controlling loss and enhancing cake quality. The prepared composites could be used to solve the technical problems in drilling fluid.

Abstract: Protein-montmorillonite composites were prepared by direct and stepwise intercalation of lysozyme(LYZ) into gallery of montmorillonite(MMT), and characterized by X-ray Diffraction (XRD), Thermal Gravimetric Analysis(TGA) and Atomic Force Microscopy(AFM). The direct intercalation experiment showed that with the increase of LYZ/MMT weight ratio from 1:1 to 4:1, the interlayer space of MMT increased from 4.2nm to 6.3nm, and the adsorption amount of lysozyme onto MMT increased from 1.05mg/mg to 1.84mg/mg. While in stepwise intercalation process, the adsorption of LYZ was obviously lower than that in direct intercalation experiment, indicating that the exchange reaction between lysozyme and POP-D2000 was incomplete in the stepwise intercalation reaction.

Abstract: Detailed studies of Li deposition on monolayer graphene grown on the Si-face SiC surface were performed using LEEM, µ- LEED, PES and ARPES. Li found to intercalate directly after the deposition at room temperature. However, excess Li was also observed on the surface and found to form a compound with carbon atoms. This compound is suggested to give rise to a new (√3x√3) R30° surface reconstruction. After annealing the (√3x√3) R30° reconstruction was vanished and only a (1x1) graphene diffraction pattern was visible. At the same time a sever change was observed on the graphene morphology, especially from the ex-situ grown graphene, i.e. extended area of cracks/wrinkles were observed. These wrinkles/cracks did not disappear even after heating at temperature of 500-1000°C when no Li signal was detected.

Abstract: Large scale, homogeneous quasi-free standing monolayer graphene is obtained on a (111) oriented cubic SiC bulk crystal. The free standing monolayer was prepared on the 3C-SiC(111) surface by hydrogen intercalation of a -reconstructed carbon monolayer, so-called zerolayer graphene, which had been grown in Ar atmosphere. The regular morphology of the surface, the complete chemical and structural decoupling of the graphene layer from the SiC substrate as well as the development of sharp monolayer p-bands are demonstrated. On the resulting sample, homogeneous graphene monolayer domains extend over areas of hundreds of square-micrometers.

Abstract: Epitaxial graphene (EG) grown on SiC(0001) resides on the so-called buffer layer. This carbon rich (6√3×6√3)R30° reconstruction is covalently bound to the topmost silicon atoms of the SiC. Decoupling the graphene buffer layer from the SiC interface is a well studied topic since successful intercalation has been shown for hydrogen [1-3]. Recently, intercalation was also shown for oxygen [4, 5]. We present ARPES, XPS and Raman spectroscopy studies to determine the quality of oxygen intercalated buffer layer samples in terms of decoupling and integrity of the transformed graphene layer. The decoupling effect is demonstrated by ARPES measurements showing a graphene-like π band. XPS shows whether the oxidation takes place in the buffer layer or at the interface. Raman spectroscopy is well suited to investigate oxygen induced defects in graphene-like material.

Abstract: Montmorillonite is usually modified with ammonium salts, in our study the selected ionic liquids were applied as modifying agents for the intercalation of montmorillonite. Surface properties of modified fillers, the zeta potential of suspended solids in the water, the oil absorption number, the impact of modifications on the tendency to agglomerate in the non-polar and polar medium were studied. The modified fillers were used in two matrices with different polarity: the ethylene-propylene copolymer EPM and hydrogenated acrylonitrile-butadiene rubber HNBR. Elastomers were crosslinked with dicumyl peroxide DCP. The influence of the variously modified fillers on the cross-linking density of the vulcanizates, rheometric and mechanical properties of filled systems were investigated. The ageing studies (thermal, atmospheric and under UV radiations) were conducted.