Structural, Morphological and Tensile Study of CdS/Polystyrene (PS) Nanocomposite

Thick film of CdS/Polystyrene (PS) nanocomposite was synthesized by dispersing nanofiller particles of CdS in PS matrix. The nanostructure of the CdS particles has been ascertained through X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Small angle x-ray scattering analysis has been performed in order to ascertain nanocomposite character of the PS/CdS sample. Scanning Electron Microscopy (SEM) analyses of these samples have been carried out to establish the surface morphology. The Tensile studies of prepared samples have been ascertained through Dynamic Mechanical Analyzer (DMA). This study reveals that the young's modulus and the toughness of the material are greatly influenced by the existence of interfacial energetic interaction between dispersed CdS nanofiller particles and matrix of PS

Enhanced photodegradation of methylene blue by silica coated ZnSe nanoparticles

Herein, we report synthesis of silica-coated ZnSe nanoparticles (SZNPs), by varying the mass to volume ratio of ZnSe : TEOS i.e. mass to mass ratio of ZnSe : SiO2 ranging from 0.0267 to 0.1071. These SZNPs showed enhanced photodegradation of methylene blue (MB) solution under visible light. Silica coating on ZnSe NPs  reduces the toxicity concerns for its wide use as photocatalyst. XRD of bare ZnSe NPs confirms hexagonal crystal structure, and TEM depicts size range of SZNPs around 7 nm. FTIR and Raman measurements confirm the presence of different chemical and silanol groups attached to bare ZnSe and SZNPs. Optical absorption and photoluminescence (PL) show a red shift due to silica coating on ZnSe NPs compared to bare ZnSe. This is due to silanization of ZnSe, as silica shell reduces the recombination of photon-generated electron and hole pairs. Photocatalytic experiments on methylene blue (MB) by bare and SZNPs have been conducted, optimal SZNPs i.e. 0.0535 sample (mass ratio of ZnSe:SiO2) exhibits enhanced photo-generated free radicals. An increase in photodegradation of SZNPs, i.e. from 35 to 46% has been observed compared to bare counterparts (ZnSe). Stability decreased by only 7% after 4th cycle of reuse, depicting efficacy of the SZNPs photocatalyst in the degradation of MB. A pseudo-first-order reaction kinetics has been observed for photodegradation of MB with highest rate constant of 8.6 × 10-3 min-1 for SZNPs (1.0000:0.0535) sample

Synthesis, characterization and optical properties of CdSe/CdS and CdSe/ZnS core-shell nanoparticles

Controlled organic synthesis method used for the preparation of cadmium selenide (CdSe) quantum dots, which are covered with cadmium sulfide (CdS) and zinc sulfide (ZnS) using TOP mediated has been presented in this paper. The size, shape, internal structure, chemical composition and functional groups of the core-shell nanoparticles were analyzed using X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, energy dispersive spectra and FTIR. These studies show that the particle size is in 2-10 nm range with hexagonal phase. The optical properties were analyzed through UV-visible spectroscopy, photoluminescence spectroscopy and micro-Raman spectroscopy. Photoluminescence blue shift and broadening of Raman spectrum further confirm the narrow size of particles

Synthesis, characterization and electrical properties of GO/PANI/NPs (NPs = CdSe, CdSe/CdS, CdSe/ZnS) nanocomposites

In this paper, GO/PANI/NPs (NPs = CdSe, CdSe/CdS, CdSe/ZnS) nanocomposites have been prepared using chemical method. The electrical properties of CdSe quantum dots, core shell nanoparticles (CdSe@CdS and CdSe@ZnS), graphene oxide/polyaniline nanocomposite (GO/PANI) and graphene oxide/polyaniline/nanoparticles (GO/PANI/NPs) nanocomposites have been measured using electrometer/high resistance meter (Keithley 6517A) at different wt% ratio. The above obtained nanoparticles (CdSe, CdSe@CdS and CdSe@ZnS) show the electrical current in nano ampere (nA) range while GO/PANI nanocomposites show the electrical current in miliampere (mA) range in the I-V measurement. The results of this study have been expected to reveal the effect of finite particle size on the conductivity of nanoparticles. The observed electrical conductivity of GO/PANI/NPs nanocomposites has been significantly reduced after the mixing of above obtained nanoparticles in different wt% ratio with GO/PANI nanocomposites. The knowledge of electrical conductivity and the effective mechanism for the conduction in nanocomposite is important for the fabrication of an electronic device such as solar cell

Electrical Study of Al/n-ZnS Schottky Junction on Polymer Substrate

A study has been made on the behaviour of Al/n-ZnS thin film junction on Polyethylene terephthalate (PET) grown using thermal evaporation method. Current-Voltage (I-V) characteristics of this junction show that the Aluminium (Al) makes Schottky contact with n-ZnS (Zinc Sulfide). Intrinsic and contact properties such as saturation current, barrier height, ideality factor and series resistance were calculated from the I-V characteristics. The conduction seems to be predominantly due to thermoionic emission-diffusion mechanism. An effort has also been made to carry out the optical study of ZnS thin film using spectrophotometer. Band gap of n-ZnS thin film is determined through absorption spectra using the Tauc's extrapolation. A band diagram of Al/n-ZnS has been proposed using the so obtained data

Measurement of structural and optical band gaps of Cd_1-xZn_xS (<i style="">x</i> = 4 and 6)<b style=""> </b>nanomaterials

125-128The sulphides of cadmium and zinc are widely used materials due to their suitable energy band gaps. Their energy band gap depends on the particle size. The materials have been prepared using a simple solution of CdCl2 and ZnCl2 mixed in proper ratio without use of thiophenol. Precipitate of CdZnS is obtained by passing H2S, liberated from heated thiourea through this solution. It is confirmed by X-ray diffraction (XRD) and optical band gap estimation that materials prepared are nano-materials. The optical band gap of these materials has been determined in order to establish a relationship between energy band gap of bulk and nanomaterial. It has been noticed that optical band increases with the increase of Zn concentration in CdZnS

Temperature dependence of <i style="">dc </i>conductivity in polyaniline-metal halide composites

767-770Polyaniline (PANI) and its metal halide composites of trivalent metal ions of Ni and Co have been synthesized with various compositions (0, 50, 100 M%) by chemical oxidative polymerization technique with ammonium peroxydisulphate in aqueous hydrochloric acid medium. I-V characteristics of these materials at room temperature as well as function of temperature (313-393K) have been studied. The temperature and composition dependence of dc conductivity for these materials has been investigated. The dependence of conductivity on temperature is suggestive of the metallic nature of the composites and shows positive temperature coefficient of resistance. The variation of electrical conductivity in the composition shows the lowest conductivity for Co-Ni (50-50) over the values obtained for Ni (100) and Co (100) separately. This interesting result can be explained on the basis of bonding of cobalt and nickel with polyaniline matrix during their polymerization

Optical and structural properties of CdS thick film

729-731Cadmium sulphide film has been prepared in open-air atmosphere by sintering technique-using ZnCl2 as an adhesive source and glycol as a binder. The reflection spectra of covered sintered film of CdS are recorded by a spectrophotometer at room temperature in the wavelength range 300-700 nm. From reflection spectra, energy band gap has been determined. It is found that energy band gap of this film is 2.57 eV, which is the energy band gap of Cd0.8Zn0.2S. This is suggestive of the fact that Cd0.8Zn0.2S is a wide band gap semiconducting material. X-ray diffraction patterns also confirm the formation of Cd0.8Zn0.2S

Structural and thermal characterization of metal halides doped polypyrrole

414-416Polypyrrole and its metal halide composites have been synthesized by chemical oxidation polymerization technique with ammonium peroxisulphate (oxidant) in aqueous hydrochloric acid medium. structural characterization of polypyrrole samples S1 (100% Co), S2 (25%Ni -75%Co), S3 (50%Ni -50%Co), S4 (75%Ni - 25%Co) and S5 (100%Ni) has been made by XRD and FTIR spectroscopy. Thermal transport properties such as effective thermal conductivity (λe) and effective thermal diffusivity (χe) of these samples have been measured simultaneously at room temperature and normal pressure using transient plane source (TPS) technique. The values of effective thermal conductivity and effective thermal diffusivity are found higher in all the above-mentioned samples except sample S3 (50%Ni-50%Co). This result can be explained on the basis of bonding of cobalt and nickel with polypyrrole matrix during their polymerization