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2019
UV-Vis technique is a compulsory technique for the optical study of the materials. Optical study helps the researcher for the application s of nanomaterials for different uses. Different devices are fabricated on the basis of optical properties of the materials especially solar cells. With the help of this technique optical band gap can be calculated which helps to choose the materials for the energy conversion purpose like light energy to electrical energy in solar cell. Also, from this technique purity of the sample can be measured by comparison with the reference solution. Here results of different materials are described which can help to better understand the analysis of Uv-Vis spectroscopy results.
Colloids and Interfaces
In this article we report the production of metal oxide (TiFe2O4, ZnFe2O4) nanoparticles by pulsed laser ablation technique in a liquid environment. We used nanosecond Nd: YAG laser systems working at 532 nm and 1064 nm of wavelength and the energy of the laser beam was kept constant at 80 mJ. Absorbance spectra, surface plasmon resonance, optical band-gap, and nanoparticle morphology were investigated using ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Changing the wavelength of the laser for growth, nanoparticles showed shift between the absorbance and surface plasmon resonance peaks in their UV-Vis spectra, which implies that the optical properties of the colloid nanoparticles depend on laser parameters. This was confirmed with the variation of the band gap energy. Furthermore, redshift for the absorbance peak was observed for samples as-grown at 532 nm around 150 nm as a function of time prepara...
Silver nanoparticles were synthesized using Euphorbia Confinalis stem extract which is an eco-friendly and cost effective method compared to other synthesis protocols like chemical and physical methods. Euphorbia Confinalis which is used traditionally for therapeutic uses was responsible for capping and reducing silver ions to silver nanoparticles. Silver was of a particular interest for this process due to its evocative physical and chemical properties. The silver nanoparticles synthesized were quantified and characterized using visual examination of the color changes, UV-Visible spectros-copy and Fourier Transform Infrared spectroscopy. The antimicro-bial activity of the synthesized nanoparticles was done by agar disc diffusion method tested against Escherichia coli (Gram-Negative) and Staphylococcus aureus (Gram-Positive). The synthesis of silver nanoparticles was confirmed by color change of AgNO 3 to reddish brown upon addition of the Euphorbia Confinalis stem extract. The UV-Vis spectrum showed broad absorption band at 433nm corresponding to that of Surface Plasmon Resonance of silver nanoparti-cles. The FTIR analysis showed the presence of aromatic, aliphatic and amines and these observations suggested the presence and binding of organic compounds with silver nanoparticles. ranging from bio sensing and catalysis to optics, antimicrobial activity, computer transistors, electrometers, chemical sensors, and wireless electronic logic and memory schemes [2]. The chemical, physical and biological properties of the nanoparticles in this range changes in fundamental ways from the properties of both individual atoms/molecules and of the corresponding bulk materials. Nanoparticles are present in several different morphologies such as spheres, cylinders, platelets, tubes and can be made of materials of varied chemical nature, the most common being metals, metal oxides, silicates, non-oxide ceramics, polymers, organics, carbon and biomolecules. Silver nanoparticles are of interest because of the unique properties (size and shape depending optical, electrical, and magnetic properties) which can be incorporated into antimicrobial applications, biosensor materials, composite fibers, cryogenic superconducting materials, cosmetic products, and electronic components. Several physical and chemical methods have been used for synthesizing and stabilizing silver nanoparticles [3]. The most popular chemical approaches, including chemical reduction using a variety of organic and inorganic reducing agents, electrochemical techniques, physicochemical reduction, and radiolysis are widely used for the synthesis of silver nanoparticles. Recently, nanoparticle synthesis is among the most interesting scientific areas of inquiry, and there is growing attention to produce nanoparticles using environmentally friendly methods (green chemistry). Green synthesis approaches include mixed-valence polyoxometalates, polysaccharides, Tollens, biological, and irradiation methods which have advantages over conventional methods involving chemical agents associated with environmental toxicity. Green synthesis of silver AgNPs is cost effective and environmentally friendly relative to chemical and physical methods. This involves the synthesis of AgNPs by plant extracts and silver nitrate solution. In this synthesis phytochemical compounds in the plant extracts are responsible for the bio reduction of Ag + ions to AgNPs. The main phytochemicals involved are terpenoids, flavones, ketones, aldehydes, amides, and carboxylic acids. In this work, Euphorbia Confinalis (chikondekonde) stem extracts were used for the first time to synthesize AgNPs. We selected Euphorbia Confinalis because it has been reported that the Euphorbia family's (Euphorbiaceae) white latex contain oils, keto steroids, glycosides, couroupitine, indirubin, isatin, phenolic compounds, flavonoids, and terpenoids [4]. We exploited the presence of these compounds to perform the reduction of Ag + ions to form AgNPs. Furthermore, Euphorbia Confinalis is an indigenous plant in Zimbabwe and is readily found in rocky hills in deciduous woodland but without any current commercial application. Again, the tree has varied traditional medicinal uses in Zimbabwean communities which include treatment of lesions, wounds on cattle, treating warts, tumors, skin diseases and tooth ache. By synthesizing AgNPs using Euphorbia Confinalis plant extracts we also envisage the addition of these medicinal properties/ functionalities to the AgNPs, resulting in combinational antimicrobial activity. A drug with such combinational or synergistic properties can result in combating incidences of drug resistance against pathogenic
Aggregation kinetics of gold nanoparticles (Au NPs) interaction in the presence of some diolefinic dyes, namely 1,4-bis (β-pyridyl-2-vinyl)benzene (P2VB), 1,4 bis(2-methylstyryl) benzene (MSB) and 2,5 distyrylpyrazine (DSP), were studied in methanol using steady state UV-Vis spectrophotometry and stopped-flow spectrophotometry. All three dyes induced the aggregation of Au NPs, but with different rates. The rate of interaction of P2VB and MSB with Au NPs were in time-scale of milliseconds, 6 ms-1 and 3.25 ms-1, respectively, while the interaction between DSP and Au NPs occurred in time-scale of minutes. The rates of interaction between Au NPs and these dyes go in the order of P2VB > MSB » DSP. The density functional theory (CAM-B3LYP) predicted that the dye with higher group charge on the terminal moieties possess higher affinity toward the aggregation as it strengthen its electrostatic interactions with the citrate-capped Au NPs.
We report the production of metal oxide (TiFe2O4, ZnFe2O4) nanoparticles by pulsed laser ablation technique in liquid environment. We used nano second Nd: YAG laser systems working at 532 nm and 1064 nm of wavelength, the energy of the laser beam was kept constant at 80 mJ. Absorbance spectra, surface plasmon resonance, optical band-gap and nanoparticle morphology were investigated using ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Changing the wavelength of the laser for growth, nanoparticles shown shift between the absorbance and surface plasmon resonance peaks in their UV-Vis spectra, this implies that the optical properties of the colloid nanoparticles depends on laser parameters, this was confirmed with the variation of the band gap energy. Furthermore, red shift for the absorbance peak was observed for samples as-growth at 532 nm around the 150 nm as function of time preparation. ...
Nanomaterials
The photochemical synthesis of two-dimensional (2D) nanostructured from semiconductor materials is unique and challenging. We report, for the first time, the photochemical synthesis of 2D tin di/sulfide (PS-SnS2-x, x = 0 or 1) from thioacetamide (TAA) and tin (IV) chloride in an aqueous system. The synthesized PS-SnS2-x were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), a particle size distribution analyzer, X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), thermal analysis, UV–Vis diffuse reflectance spectroscopy (DR UV–Vis), and photoluminescence (PL) spectroscopy. In this study, the PS-SnS2-x showed hexagonally closed-packed crystals having nanosheets morphology with the average size of 870 nm. Furthermore, the nanosheets PS-SnS2-x demonstrated reusable photo-degradation of methylene blue (MB) dye as a water pol...
Journal of Nanomaterials & Molecular Nanotechnology, 2016
This work, conducted biological synthesis and characterization of gold nanoparticles (AuNPs) through environmentally friendly technology using plant extracts: cactus (Opuntia sp.), onion (Allum sp.), pear (Pyrus sp.), coffee (Coffea sp.) and laurel (Laurus sp.), as a reducing agent and stabilizers. The methodology consists in merging Turkevich et al., 1951 and Rico-Moctezuma et al., 2010 techniques. The characterization with UV-Visible spectrophotometry determined maximum absorbance at 527-537 nm, corresponding with previously reported AuNPs absorbance, while transmission electron microscopy (TEM) and Atomic Force Microscopy (AFM) confirmed that the gold nanoparticles biosynthesis produced different shapes, including spheres, cubes, cones, cylinders and others with a size of 5-100 nm depending on the extract used, so that the proposed method is useful, eco-friendly, quick and inexpensive to synthesize AuNPs. Furthermore these AuNPs can be functionalized.
Journal of Chemistry
Even though the photocatalytic processes are a good technology for treatment of toxic organic pollutants, the majority of current photocatalysts cannot utilize sunlight sufficiently to realize the decomposition of these organic pollutants. As stated by various researchers, metal oxide nanoparticles have a significant photocatalytic performance under visible light source. Among various chemical and physical methods used to synthesize nanostructured silver oxide, green synthetic route is a cheaper and environmental friendly method. To confirm the optimum production of Ag2O NPs, effect of pH, extract concentration, metal ion concentration, and contact time were optimized. The structure, morphology, crystallinity, size, purity, elemental composition, and optical properties of obtained Ag2O NPs were characterized by different techniques, such as scanning electron microscopy (SEM), transmission electron microscope (HRTEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-r...
International Journal for Research in Applied Science & Engineering Technology, 2020
Biofuels are progressing rapidly as alternative renewable energy sources because of their non-polluting traits and their low cost compared to fossil fuels. However, the main focus is the use of novel techniques to maximize the yields in order to effectively commercialize biofuel. Nanotechnology is an enormous and intensifying field of research owing to its broad area of application in various fields, particularly in the biomedical and pharmaceutical fields. The various unique properties of nanoparticles have attracted the scientists to investigate their role in biofuel production processes. The application of nanoparticles in biofuel production is still in infancy stage. The present review analytically discusses the different studies that have been carried out to explore the role of nanoparticles in biofuel production i.e. in the production of biohydrogen, biogas, biodiesel and bioethanol. The review also deals with the nanomaterials characterization techniques.
Indones. J. Chem., 2019
The aim of this manuscript was to modify the ZnS surface by incorporating with CdS photocatalyst. This manner led to depressing the recombination process and increasing the activity. The X-ray Powder Diffraction (XRD) data were proved that the CdS incorporated with ZnS and formed ZnS-CdS nanocomposite by observing new peaks at 26.92 o , 28.62 o , 30.52 o , and 47.26°. Based on the Atomic Force Microscopy (AFM) analysis and Tauc equation, the particle sizes for all samples were raised with decreased the band gap values. The activation energy for decolorization of Congo red with the using ZnS is found to be more than that value for the using prepared ZnS-CdS nanocomposite. The percentage of efficiency was found to be increased with modified the ZnS surface.
Materials, 2019
International Journal of Chemistry, 2019
Journal of Fashion Technology & Textile Engineering, 2015
Evincepub Publishing, 2020
Journal of Luminescence , 2020
Nanomaterials
2019
Journal of Nanomedicine & Nanotechnology, 2015
Journal of Alloys and Compounds, 2013
Central European Journal of Chemistry, 2014
Journal of Industrial and Engineering Chemistry, 2014
Bulletin of Materials Science, 2015
Materials Chemistry and Physics, 1988
Surfaces and Interfaces, 2020
Scientific Reports , 2020
Journal of Composites Science
International journal of nanomedicine, 2020
Biogenesis of ZnO nanoparticles: RSC, 2019