Showing papers by "Andrews Nirmala Grace published in 2014"
TL;DR: In this article, the effect of cationic surfactant viz. cetyl trimethyl ammonium bromide on the morphology of as-prepared CuS nanostructures was investigated.
123 citations
TL;DR: Graphene-Fe3O4 (G-Fe 3O4) composite was prepared from graphene oxide (GO) and FeCl3·6H2O by a one-step solvothermal route as discussed by the authors.
Abstract: Graphene–Fe3O4 (G–Fe3O4) composite was prepared from graphene oxide (GO) and FeCl3·6H2O by a one-step solvothermal route. The as-prepared composite was characterized by field-emission scanning electron microscopy, transmission electron microscopy, dynamic light scattering and X-ray powder diffraction. SEM analysis shows the presence of Fe3O4 spheres with size ranging between 200 and 250 nm, which are distributed and firmly anchored onto the wrinkled graphene layers with a high density. The resulting G–Fe3O4 composite shows extraordinary adsorption capacity and fast adsorption rates for the removal of Pb metal ions and organic dyes from aqueous solution. The adsorption isotherm and thermodynamics were investigated in detail, and the results show that the adsorption data was best fitted with the Langmuir adsorption isotherm model. From the thermodynamics investigation, it was found that the adsorption process is spontaneous and endothermic in nature. Thus, the as-prepared composite can be effectively utilized for the removal of various heavy metal ions and organic dyes. Simultaneously, the photodegradation of methylene blue was studied, and the recycling degradation capacity of dye by G–Fe3O4 was analyzed up to 5 cycles, which remained consistent up to ∼97% degradation of the methylene blue dye. Although iron oxide has an affinity towards bacterial cells, its composite with graphene still show antibacterial property. Almost 99.56% cells were viable when treated with Fe3O4 nanoparticle, whereas with the composite barely 3% cells survived. Later, the release of ROS was also investigated by membrane and oxidative stress assay. Total protein degradation was analyzed to confirm the effect of the G–Fe3O4 composite on E. coli cells.
104 citations
TL;DR: In this article, an electrochemical reduction of CO 2 using Cu 2 O nanoparticle decorated polyaniline matrix (PANI/Cu 2 O) in 0.1 M tetrabutylammonium perchlorate and methanol electrolyte was investigated under ambient conditions.
104 citations
TL;DR: In this article, the structural, morphological and physical properties of Co9S8/graphene nanocomposites were analyzed by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), XPS, and thermogravimetric analysis (TGA).
Abstract: Co9S8/graphene nanocomposites (Co9S8/G) at various concentrations of graphene and Co9S8 were prepared by a simple chemical route from cobalt nitrate and graphene as precursors in the presence of PVP as surfactant and thioacetamide (TAA) as sulfur source. To gain knowledge about the structural, morphological and physical properties, the composite material was analyzed by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric Analysis (TGA). SEM measurements showed the presence of well dispersed, ∼300 nm sized Co9S8 nanoflakes. To assess the properties of the nanocomposites for their applicability in supercapacitors, electrochemical analysis was carried out in 6 M KOH electrolyte. A maximum specific capacitance of 808 F g−1 was observed for Co9S8/G-d at 5 mV s−1 scan rate. Galvanostatic charge–discharge curves showed the excellent cyclic stability of Co9S8/G-d composite with higher charge–discharge duration than pure Co9S8. The excellent electrochemical performance of the composite could be due to the better electrical conductivity behavior of graphene on Co9S8 nanoflakes.
98 citations
TL;DR: In this article, a CoFe2O4 + 20% reduced graphene oxide (rGO) composite with alginate was synthesized by a simple solvothermal process and the electrochemical properties of the composite were evaluated using polyvinylidene fluoride and Na-alginate as binder materials.
Abstract: Porous CoFe2O4 nanoclusters with different concentrations of graphene based composites were synthesized by a simple solvothermal process. The electrochemical properties of prepared CoFe2O4–reduced graphene oxide (rGO) composites were evaluated using polyvinylidene fluoride and Na-alginate as binder materials. The CoFe2O4 + 20% rGO composite with alginate exhibited a high stable capacity of 1040 mA h g−1 at 0.1 C (91 mA g−1) rate with excellent rate capability. The observed enhancement in electrochemical properties of the CoFe2O4 + 20% rGO composite with alginate is due to the high stability and good transportation network while charging–discharging.
69 citations
TL;DR: In this paper, the supercapacitive properties of the Co3S4-NG-7 composite were evaluated with cyclic voltammetry and galvanostatic charge discharge techniques.
Abstract: Nanocomposites of Co3S4 grown on nitrogen-doped graphene (NG) (Co3S4-NG) have been prepared at various concentrations of NG. The supercapacitive behaviors of the developed nanocomposites were assessed with cyclic voltammetry and galvanostatic charge discharge techniques. The nanocomposites exhibit excellent capacitive behavior with a high specific capacitance of 2427 F/g at 2 mV/s in Co3S4-NG-7 composite (7 indicates the percentage weight ratio of NG). The superior electrochemical performances could be due to synergistic effects between Co3S4 and NG, high charge mobility and good flexibility of graphene structures. These results indicate that the developed hybrid materials are promising candidates for high performance energy applications.
62 citations
TL;DR: In this paper, a direct electrocatalytic activity of glucose oxidation on cuprous oxide modified glassy carbon electrode was reported, which was synthesized by a simple wet chemical route in the absence of surfactants.
Abstract: A direct electrocatalytic activity of glucose oxidation on cuprous oxide modified glassy carbon electrode is reported. Cu2O nanocubes were synthesized by a simple wet chemical route in the absence of surfactants. Purity, shape and morphology of Cu2O are characterized by XRD, SEM, XPS and DRS-UV. The Cu2O nanocubes-modified glassy carbon electrode (GCE) exhibited high electrocatalytic activity towards glucose oxidation compared with bare GCE electrode. At an applied potential of +0.60 V, the Cu2O electrode presented a high sensitivity of 121.7 μA/mM. A linear response was obtained from 0 to 500 μM, a response time less than 5 s and a detection limit of 38 μM (signal/noise=3). The Cu2O nanocubes modified electrode was stable towards interfering molecules like uric acid (UA), ascorbic acid (AA) and dopamine (DA). In short, a facile chemical preparation process of cuprous oxide nanocubes, and the fabricated modified electrode allow highly sensitive, selective, and fast amperometric sensing of glucose, which is promising for the future development of non-enzymatic glucose sensors.
56 citations
TL;DR: In this article, the effect of cationic surfactant, namely, Cetyltrimethylammonium bromide (CTAB), on the morphology of the products was investigated.
Abstract: CuS nanostructures have been successfully synthesized by hydrothermal route using copper nitrate and sodium thiosulphate as copper and sulfur precursors. Investigations were done to probe the effect of cationic surfactant, namely, Cetyltrimethylammonium bromide (CTAB) on the morphology of the products. A further study has been done to know the effect of reaction time on the morphology of CuS nanostructures. The FE-SEM results showed that the CuS products synthesized in CTAB were hexagonal plates and the samples prepared without CTAB were nanoplate like morphology of sizes about 40–80 nm. Presence of nanoplate-like structure of size about 40–80 nm was observed for the sample without CTAB. The synthesized CuS nanostructures were characterized by X-ray diffraction (XRD), FE-SEM, DRS-UV-Vis spectroscopy, and FT-IR spectroscopy. A possible growth mechanism has been elucidated for the growth of CuS nanostructures.
52 citations
TL;DR: In this article, a highly sensitive and selective Cr(VI) sensor with graphene-based nanocomposites film as an enhanced sensing platform is reported, which combines the advantages of AuNPs and graphene nanosheets because of the synergistic effect between them.
Abstract: A highly sensitive and selective Cr(VI) sensor with graphene-based nanocomposites film as an enhanced sensing platform is reported. The detection of chromium species is a challenging task because of the different possible oxidation states in which the element can occur. The sensing film was developed by homogenously distributing Au nanoparticles (AuNPs) onto the two-dimensional (2D) graphene nanosheet matrix by electrochemical method. Such nanostructured composite film platforms combine the advantages of AuNPs and graphene nanosheets because of the synergistic effect between them. This effect greatly facilitates the electron-transfer processes and the sensing behavior for Cr(VI) detection, leading to a remarkably improved sensitivity and selectivity. The interference from other heavy metal ions is studied in detail. Such sensing elements are very promising for practical environmental monitoring applications.
23 citations
TL;DR: In this article, the authors reported the behavior of higher magnetization values for zero field cooled condition to that of Field Cooled for the reduced graphene oxide-Nickel/NiFe2O4 (RGO-Ni/NF) nanocomposite.
Abstract: Magnetic Reduced Graphene Oxide-Nickel/NiFe2O4 (RGO-Ni/NF) nanocomposite has been synthesized by one pot solvothermal method. Respective phase formations and their purities in the composite are confirmed by High Resolution Transmission Electron Microscope and X Ray Diffraction, respectively. For the RGO-Ni/NF composite material finite-size effects lead to the anomalous magnetic behavior, which is corroborated in temperature and field dependent magnetization curves. Here, we are reporting the behavior of higher magnetization values for Zero Field Cooled condition to that of Field Cooled for the RGO-Ni/NF nanocomposite. Also, the observed negative and positive moments in Hysteresis loops at relatively smaller applied fields (100 Oe and 200 Oe) are explained on the basis of surface spin disorder.
21 citations
19 Jun 2014
TL;DR: Graphene supported palladium electrocatalysts (Pd/G) is prepared using a facile microwave reduction method; which assists reduction of graphene oxide and further leads to formation of palladium nanoparticles as discussed by the authors.
Abstract: Graphene found to be one of the best alternative to carbon nanotubes due to its superior properties and distinctive nanostructure. Graphene supported palladium electrocatalysts (Pd/G) is prepared using a facile microwave reduction method; which assists reduction of graphene oxide and further leads to formation of palladium nanoparticles. The structural characteristics of the prepared materials are characterized using FE-SEM, EDAX, XRD, FTIR spectroscopy and Raman spectroscopy. Electrocatalytic activity of the prepared electrocatalysts with respect to Methanol Oxidation Reaction (MOR) is analyzed using cyclic voltammetry. In addition, Vulcan carbon supported palladium electrocatlyst (Pd/G) is also prepared via same method for the evaluation of Pd/G. Further, electrocatalytic performance of prepared materials is investigated. Experiments are also carried out at different loading of palladium onto graphene matrix. This prepared graphene supported electrocatalysts having high electrocatalytic can be considered to be a better substitute for fuel cells anode material.