Murugan Saranya

Co9S8 nanoflakes on graphene (Co9S8/G) nanocomposites for high performance supercapacitors

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.

A template-free facile approach for the synthesis of CuS–rGO nanocomposites towards enhanced photocatalytic reduction of organic contaminants and textile effluents

Copper sulfide–reduced graphene oxide nanocomposites were synthesized hydrothermally from copper nitrate and thiourea as precursor materials. In the hydrothermal route, rGO is formed by the reduction of GO with simultaneous formation of CuS–rGO nanocomposites. The CuS–rGO nanocomposites was investigated using powder XRD, FE-SEM, HR-TEM, DRS UV-vis spectroscopy, photoluminescence (PL) measurements, infra-red spectroscopy and photoelectron spectroscopy (XPS). DRS UV-vis measurements of CuS–rGO nanocomposites feature a strong absorption in the range 400–800 nm, which suggests that they have photocatalysis applications. Three different composites were prepared with different loadings of rGO to study the effect of loading on methylene blue (MB) dye degradation. The photocatalytic properties of the composites were tested in a visible light photoreactor chamber. The CuS–rGO nanocomposites were found to exhibit high photocatalytic activities with a maximum efficiency of 99.27% after 60 min in a visible source. These interesting and enhanced catalytic properties of CuS–rGO-x nanocomposite was further tested for organic contaminant and textile effluents collected from two different sites situated in the Thirupur textile industries, India. Results showed the CuS–rGO-x nanocomposite is an efficient photocatalyst.

Synthesis of Cobalt Sulfide–Graphene (CoS/G) Nanocomposites for Supercapacitor Applications

Cobalt sulfide (CoS) and graphene nanocomposites were prepared from cobalt nitrate, thioacetamide, and graphene as starting materials in the presence of poly(vinylpyrrolidone) as surfactant. Furthermore, its morphology and properties were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope, diffusive reflectance ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and electrochemical measurements. The XRD reveals the amorphous nature of the nanocomposites. The as-prepared nanocomposites were tested for its supercapacitance property by cyclic voltammetric (CV) experiment in 6M KOH electrolyte. CV was performed at a potential range of 0 to -0.8 V at different scan rates, and results show an excellent capacitive behavior of the nanocomposites. A maximum specific capacitance of 2423.3 F/g was obtained at a scan rate of 5 mV/s.

MnS nanocomposites based on doped graphene: simple synthesis by a wet chemical route and improved electrochemical properties as an electrode material for supercapacitors

Nanocomposites of MnS anchored on graphene, nitrogen-doped graphene and boron-doped graphene have been prepared by a simple wet chemical process. The effect of graphene concentration in MnS and the effect of doping type in the composites are studied through the use of various characterization techniques. An electrochemical performance better than that of pure MnS has been observed in the graphene based composites. The doping of N and B atoms in graphene can further enhance the electrochemical activities of the nanocomposites. The present study demonstrates that MnS with doped graphene has large electrode/electrolyte interfaces, which offers more active sites and ensures a high charge storage capacity of the composite. A maximum specific capacitance of 696.6 and 353.8 F g−1 are measured for MnS/BG-9 and MnS/NG-9 composite, respectively, at a 5 mV s−1 scan rate, whereas the pure graphene composite (MnS/G-9) exhibits only a maximum specific capacitance of 156 F g−1.

Growth of CuS Nanostructures by Hydrothermal Route and Its Optical Properties

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.

Graphene/Gold Nanocomposites-Based Thin Films as an Enhanced Sensing Platform for Voltammetric Detection of Cr(VI) Ions

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.

Hydrothermal Synthesis of CuS Nanostructures with Different Morphology

Cus Nanostructures Have Been Successfully Prepared from Copper Chloride with Two Different Sulfur Sources Like Thiourea and Sodium Thiosulphate by Hydrothermal Route at 150oC. The Growth of Cus Nanostructures Were Investigated for Different Reaction Time Periods of 5 Hrs and 24 Hrs Respectively Using Water as Solvent. the as-Synthesized Cus Nanostructures Are Characterized by X-Ray Diffraction (XRD) and Field-Emission Scanning Electron Microscopy (FE-SEM). XRD Pattern Indicates that the Prepared Cus Nanomaterials Are in Pure Hexagonal Phase. Results Show that Cus Nanomaterials with Different Hierarchical Structures Like Urchins, Nanoplates Etc,. Were Obtained at Different Experimental Conditions. A Systematic Investigation of the Final End Products Has Been Done to Elucidate the Formation Mechanism at Different Experimental Parameters. The Optical Properties of the Cus Structures Were Studied by UV-Vis Absorption Analysis, which Showed Broad Absorption in the Visible Region. The Optical Band Gap of the Cus Nanomaterials Were Found as 2.2 Ev and 2.18 Ev for Different Sulfur Sources.

Synthesis and characterisation of CuS nanomaterials using hydrothermal route

Copper sulphide (CuS) nanomaterials with interesting morphology were synthesised using copper nitrate trihydrate, thiourea and water as a solvent by a simple hydrothermal route. A systematic investigation was carried out to investigate the effect of reaction time (5, 16 and 24 h) at 150°C on the morphology of the materials. Without the use of any template or additives, shape controlled synthesis of CuS nanocrystallites were achieved. The possible mechanism for the formation of the various nanostructures of CuS in this system is discussed. The prepared materials were characterised by X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and DRS-UV–Vis absorption analysis. The UV–Vis spectrum shows that it is the promising material which can absorb in the visible region and hence could be used for photocatalytic applications. In addition, the electrochemical characteristic of the synthesised material was investigated by cyclic voltammetric analysis, which shows that CuS could be used for electrocatalytic applications.

Growth of Carbon Nanotubes Using MgO Supported Mo-Co Catalysts by Thermal Chemical Vapor Deposition Technique

A simple method is developed for the synthesis of carbon nanotubes (CNTs) using Mo-Co/MgO catalyst by a thermal chemical vapor deposition (CVD) technique. Acetylene was used as the source of carbon and nitrogen as carrier gas. A series of MgO supported Mo-Co catalysts were prepared by the combustion route using urea as the fuel at different stoichiometric ratios. It was found that a higher yield of carbon nanotubes was obtained by the developed catalysts. Also, the addition of molybdenum to Co/MgO catalysts could remarkably increase the yield and also improve the quality of CNTs from thermal CVD with acetylene as precursor gas. The morphology of the catalysts and CNTs obtained was studied by field emission scanning electron microscope (FE-SEM). Other techniques like Raman spectroscopy and XRD were also employed to know the physico-chemical properties of the samples.