Synthesis and photoluminescence studies on catalytically grown Zn1 – xMnxS nanowires

Zn1 – xMnxS alloy nanowires with composition (x = 0.0, 0.1 and 0.3) have been successfully synthesized by a simple thermal evaporation on the silicon substrate coated with a gold film of 2 nm thickness. X-ray powder diffraction measurements reveal that as synthesized products were hexagonal wurtzite structure. The as grown nanowires have been investigated by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive Analysis of X-rays (EDAX) and photoluminescence studies. The results reveal that the as grown nanowires consist of Zn, Mn, and S material and diameter ranging from 70 - 150 nm with lengths up to several tens of micrometers. Photoluminescence studies on Zn1 – xMnxS exhibited peaks at 600 and 613 nm for x = 0.1 and 0.3 respectively. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/1053

Fabrication Of ZnxCd1 – xSe Nanowires By CVD Process And Photoluminescence Studies

ZnxCd1 – xSe alloy nanowires with composition x = 0.2, 0.5 have been successfully synthesized by a simple thermal evaporation on the silicon substrate coated with a gold film of 20 Å thickness. The as-synthesized alloy nanowires, 70 - 150 nm in diameter and several tens of micrometer in length. The nanowires are single crystalline revealed from Transmission electron microscopy (TEM) and XRD measurement. The structure of ZnxCd1 – xSe nanowires are hexagonal wurtzite with [01-10] growth direction. Energy gap of the ZnxCd1 – xSe nanowires are determined from micro photoluminescence measurements. The energy gap increases with increasing Zn concentration. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/954

Effect of Mg Doping on the Structural and Optical Properties of CdS Nanoparticles Synthesized by co-Precipitation Method

Cd1 – xMgxS (x = 0.00, 0.05, 0.10, 0.15 and 0.20) nanoparticles were synthesized by co-precipitation method for the first time. Compositional, morphological, structural and optical studies of the as prepared samples were carried out by X-ray diffraction (XRD), Energy dispersive analysis of X-rays (EDAX), Scanning electron microscopy (SEM), Diffuse reflectance spectroscopy (DRS) and Photoluminescence (PL) techniques. XRD studies revealed the structural phase transition from cubic to hexagonal and increase in the average grain size of the nanoparticles (lie in the range 1.4 nm to 2.8 nm) with increasing Mg content. EDAX spectra rules out the existence of impurities in the samples. Bandgap widening was observed in all the samples compared to bulk CdS (2.42 eV). Decrease in bandgap (3.02 eV to 2.54 eV), luminescence quenching and red shift of luminescence peak position were observed with increasing Mg in Cd1 – xMgxS. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3028

Room temperature ferromagnetism and white light emissive CdS:Cr nanoparticles synthesized by chemical co-precipitation method

Undoped and Cr (3% and 5%) doped CdS nanoparticles were synthesized by chemical co-precipitation method. The synthesized nanocrystalline particles are characterized by energy dispersive X-ray analysis (EDAX), scanning electron microscope (SEM), X-ray Diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL), Electron paramagnetic resonance (EPR), vibrating sample magnetometer (VSM) and Raman spectroscopy. XRD studies indicate that Cr doping in host CdS result a structural change from Cubic phase to mixed (cubic + hexagonal) phase. Due to quantum confinement effect, widening of the band gap is observed for undoped and Cr doped CdS nanoparticles compared to bulk CdS. The average particle size calculated from band gap values is in good agreement with the TEM study calculation and it is around 4-5 nm. A strong violet emission band consisting of two emission peaks is observed for undoped CdS nanoparticles, whereas for CdS:Cr nanoparticles, a broad emission band ranging from 420 nm to 730 nm with a maximum at similar to 587 nm is observed. The broad emission band is due to the overlapped emissions from variety of defects. EPR spectra of CdS:Cr samples reveal resonance signal at g = 2.143 corresponding to interacting Cr3+ ions. VSM studies indicate that the diamagnetic CdS nanoparticles are transform to ferromagnetic for 3% Cr3+ doping and the ferromagnetic nature is diminished with increasing the doping concentration to 5%. (C) 2015 Elsevier B.V. All rights reserved

Regulating charge carrier’s transportation rate via bridging ternary heterojunctions enabling CdS nanorods solar driven hydrogen evolution rate

Abstract Solar-driven hydrogen generation using single-semiconductor photocatalysts for hydrogen evolution seems to be challenging due to their poor solar to fuel conversion efficiency because of their fast charge carrier recombination. The ternary heterostructure constitutes an advanced approach to suppress the recombination of photogenerated charge carriers and has contributed a new platform for designing highly efficient photocatalytic system. Herein, we fabricated a ternary hetero-junction with ultrathin WS₂-SnS₂ nanosheets and CdS nanorods and the photocatalytic activity is studied. The optimized CdS/SnS₂-WS₂ (6 wt. %) nanostructures are found to be highly stable and exhibited highest hydrogen evolution rate of 232.45 mmol. g− 1.h− 1, which is almost 93 folds higher than that of the pristine CdS nanorods. Also, Density Functional Theory (DFT) calculations confirm that the favorable band alignment for charge transport and superior catalytic activity of newly fabricated ternary nanostructures makes it a potential candidate for solar driven hydrogen production

Green synthesis of the reduced graphene oxide-CuI quasi-shell-core nanocomposite: A highly efficient and stable solar-light-induced catalyst for organic dye degradation in water

Surfactant-free, reduced graphene oxide (RGO)-CuI quasi-shell-core nanocomposites were successfully synthesized using ultra-sonication assisted chemical method at room temperature. The morphologies, structures and optical properties of the CuI and CuI-RGO nanocomposites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transformed infrared spectroscopy (FTIR), UV-visible absorption spectroscopy, and photoluminescence (PL) spectroscopy. Morphological and structural analyses indicated that the CuI-RGO core-shell nanocomposites comprise single-crystalline face-centered cubic phase CuI nanostructures, coated with a thin RGO quasi-shell. Photocatalysis experiments revealed that the as-synthesized CuI-RGO nanocomposites exhibit remarkably enhanced photocatalytic activities and stabilities for photo degradation of Rhodamine-B (RhB) organic dye under simulated solar light irradiation. The photo degradation ability is strongly affected by the concentration of RGO in the nanocomposites; the highest photodegradation rate was obtained at a graphene loading content of 2mgmL-1 nanocomposite. The remarkable photocatalytic performance of the CuI-RGO nanocomposites mainly originates from their unique adsorption and electron-accepting and electron-transporting properties of RGO. The present work provides a novel green synthetic route to producing CuI-RGO nanocomposites without toxic solvents or reducing agents, thereby providing highly efficient and stable solar light-induced RGO-CuI quasi-shell-core nanocomposites for organic dye photo degradation in water. © 2015 Elsevier B.Vclose0

Rational Synthesis of Metal–Organic Framework-Derived Noble Metal-Free Nickel Phosphide Nanoparticles as a Highly Efficient Cocatalyst for Photocatalytic Hydrogen Evolution

Facile preparation of metal–organic framework (MOF) derived earth-abundant nickel phosphide (Ni₂P) by a simple, cost-effective procedure is described. Ni₂P is recognized as a suitable replacement for expensive noble metal cocatalysts used for H₂ production by water splitting. Ni₂P nanoparticles were used to prepare a Ni₂P/CdS composite with improved photocatalytic properties. Crystal structure and surface morphology studies showed that Ni-MOF spheres readily transform into Ni₂P particles, and TEM images indicated the presence of Ni₂P nanoparticles on CdS. The optical properties and charge carrier dynamics of the composite material exhibited better visible light absorption and improved suppression of charge carrier recombination. X-ray photoelectron spectra confirmed the presence of Ni₂P on CdS. The synthesized materials were tested for photocatalytic hydrogen production with lactic acid as a scavenger under irradiation in a solar simulator. The rate of H₂ production with Ni₂P/CdS was 62 times greater than that with pure CdS. The superior activity of the composite material is attributed to the ability of Ni₂P to separate the photoexcited charge carriers from CdS and provide good electrical conductivity. The optimized composite material also exhibited better photocatalytic activity than Pt cocatalyzed CdS. Based on the experimental results, a possible electron–hole transfer mechanism is proposed

Optimization of Active Sites of MoS₂ Nanosheets Using Nonmetal Doping and Exfoliation into Few Layers on CdS Nanorods for Enhanced Photocatalytic Hydrogen Production

Transition metal dichalcogenides (TMDs) have emerged as promising nonprecious noble-metal-free catalysts for photocatalytic applications. Among TMDs, MoS₂ has been extensively studied as a cocatalyst due to its exceptional activity for photocatalytic hydrogen evolution. However, the catalytic activity of MoS₂ is triggered only by the active S atoms on its exposed edges, whereas the majority of S atoms present on the basal plane are catalytically inactive. Doping of foreign nonmetals into the MoS₂ system is an appealing approach for activation of the basal plane surface as an alternative for increasing the concentration of catalytically active sites. Herein, we report the development of earth-abundant, few-layered, boron-doped MoS₂ nanosheets decorated on CdS nanorods (FBMC) employing simple methods and their use for photocatalytic hydrogen evolution under solar irradiation, with lactic acid as a hole scavenger, under optimal conditions. The FBMC material exhibited a high rate of H₂ production (196 mmol·h^–1·g^–1). The presence of few-layered boron-doped MoS₂ (FBM) nanosheets on the surface of CdS nanorods effectively separated the photogenerated charge carriers and improved the surface shuttling properties for efficient H₂ production due to their extraordinary number of active edge sites with superior electrical conductivity. In addition, the observed H₂ evolution rate of FBMC was much higher than that for the individual few-layered MoS₂-assisted CdS (FMC) and bulk boron-doped MoS₂/CdS (BBMC) photocatalysts. To the best of our knowledge, this is the highest H₂ production rate achieved with MoS₂-based CdS photocatalysts for water splitting under solar irradiation. Considering its low cost and high efficiency, this system has great potential as a photocatalyst for use in various fields