Transmission FTIR Spectroscopy Research Articles

Synthesis and Characterization of Novel Graphene Silicon Oxide Nanocomposite Material

ABSTRACTThe primary objective of our work is to understand the nanocomposite structure of SiO2 coated over graphene (G) nanoplatelets. An attempt has been made to synthesize G-SiO2 nanocomposite using sol-gel technique. The G-SiO2 nanocomposite is characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Raman spectroscopy, FTIR spectroscopy, and Electrochemical and Electrical measurement technique, respectively. The G-SiO2 nanocomposite reveals platelets characteristics much larger in size than the graphene nanoplatelets. The conductivity of G-SiO2 has been found to increase with an increase in the graphene ratio to SiO2 in nanocomposite material. The G-SiO2 has revealed interesting feature vibrational bands of graphene with SiO2 by varying the precursor of SiO2 with graphene moieties. The cyclic voltammetry studies have indicated the diffusion controlled system. The G-SiO2 nanocomposite shows interesting current–voltage characteristics with variation of graphene in nanocomposite. Our result is indicative of a transformable and viable G-SiO2 material for energy and electrical relay applications.

Synthesis of xanthene derivatives by employing Fe3O4nanoparticles as an effective and magnetically recoverable catalyst in water

An efficient and environmentally adapted synthesis of xanthene derivatives by condensation of a wide range of aryl aldehydes and 1,3-cyclohexanediones in water using a catalytic amount of Fe3O4 nanoparticles is explained. The Fe3O4 nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and FT-IR spectroscopy.

Monitoring catalysts at work in their final form: spectroscopic investigations on a monolithic catalyst

A monolithic vanadia-titania based catalyst has been subjected to studies with in situ FTIR spectroscopy coupled with mass spectrometry, during the SCR (Selective Catalytic Reduction) reaction. A device based on a transmission reactor cell for monolithic samples was constructed, dedicated to the study of surface species during reaction. After analysing the steady state SCR activity under industrially relevant conditions, NH(3) chemisorption phenomena as a function of temperature and the subsequent SCR reaction of NO + O(2) with chemisorbed ammonia and ammonium ion species were also investigated. The observations reported here serve as a demonstration of the great potential for the application of operando spectroscopy on monolithic systems. This cross disciplinary approach aims to identify reaction pathways, active sites, intermediate- and spectator-species for catalytic reactions under truly industrial conditions in a shaped monolithic catalyst based on monitoring chemical profiles along its channels. In particular, by demonstrating the feasibility of the approach using the technically challenging operando transmission FTIR spectroscopy methodology, we foresee easy future adaption of this approach with other surface or bulk sensitive techniques, e.g. Raman and UV-vis spectroscopy.

Fe3O4 nanoparticles: A powerful and magnetically recoverable catalyst for the synthesis of novel calix[4]resorcinarenes

Abstract A simple synthesis of novel and known calix[4]resorcinarenes derivatives has been achieved by the condensation of resorcinol and different aromatic aldehydes in the presence of catalytic amounts of Fe 3 O 4 nanoparticles under solvent-free conditions. The experimental conditions have been thoroughly optimized and established, allowing significant rate enhancements and good to excellent yields. The reactions can be run safely without using any toxic organic solvents under mild reaction conditions. The Fe 3 O 4 nanoparticles were characterized by powdered X-ray diffraction (XRD), transmission electron microscopy (TEM) and FT-IR spectroscopy.

Effect of calcination temperature on structural, vibrational, optical, and rheological properties of zirconia nanoparticles

ZrO2 nanoparticles (NPs) were prepared by a simple, versatile, and an efficient methodology based on microwave. The synthesized NPs were calcined at temperatures ranging from 100°C to 600°C. The samples were characterized by X-ray powder diffraction (XRD), transmission electron microscope (TEM), FT-IR spectroscopy, Far-IR spectroscopy, Raman spectroscopy, and UV-vis absorption spectroscopy. The results clearly showed the presence of purely monoclinic phase of zirconia when the calcination temperature exceeds 400°C. The experimental results showed that the viscosity of zirconia NPs in ethylene glycol (EG) increases with increasing the particle volume fraction and decreases with increasing temperature.

Micro/mesoporous conducting carbonized polyaniline 5-sulfosalicylate nanorods/nanotubes: Synthesis, characterization and electrocatalysis

Micro/mesoporous conducting nitrogen-containing carbon nanorods/nanotubes with high surface area, and excellent electrocatalytic activity for the oxygen reduction reaction, were synthesized by the carbonization of self-assembled polyaniline (PANI) 5-sulfosalicylate nanorods/nanotubes. Carbonization was carried out by means of gradual heating in a nitrogen atmosphere up to 800°C. The morphology of the PANI 5-sulfosalicylate was preserved after carbonization. Carbonized PANI nanostructures containing ∼10wt% of nitrogen had a conductivity of 0.8Scm−1. The influence of the carbonization on the porosity and specific surface area of the nanostructured PANI has been analyzed. The morphology, elemental composition, molecular structure, surface area, and electrical characteristics of novel carbonized nanostructured PANI were investigated by scanning and transmission electron microscopies, elemental microanalysis, FTIR and Raman spectroscopies, nitrogen adsorption–desorption and conductivity measurements, respectively. The electrocatalytic activity of carbonized PANI 5-sulfosalicylate nanorods/nanotubes material towards oxygen reduction reaction in alkaline conditions has been studied by the voltammetry with the rotating disc electrode.

Kinetic study of a complex triangular reaction system in alkaline aqueous-ethanol medium using on-line transmission FTIR spectroscopy and BTEM analysis

The kinetics of the base-catalyzed reaction of methyl 4-hydroxybenzoate in aqueous-ethanol solvent medium was studied and analyzed via combined on-line transmission FTIR spectroscopy and Band-Target Entropy Minimization (BTEM) technique. This reaction is considered complex since it involves simultaneous hydrolysis and ethanolysis reactions of methyl 4-hydrozybenzoate (MP) to form ethyl 4-hydroxybenzoate (EP) as an intermediate and sodium 4-hydroxybenzoate as a final product. The pure component spectra of the reactive species involved in the reaction were reconstructed using BTEM technique. Their corresponding real concentrations were calculated and subsequently used for analyzing the kinetics of this triangular reaction system. The effects of temperature and solvent mixture compositions were studied. In general, the results show that the rates of both hydrolysis and ethanolysis reactions increase with temperature. Addition of ethanol to the solvent mixture also reduces the rates of the hydrolysis reactions. The effect of solvent mixture on the rate of ethanolysis reaction is more complex and influenced by at least two competing factors, namely the concentration of ethoxide ion in the solution and the stabilization effect on the reactant. The enthalpy and entropy activation parameters, ΔH‡ and ΔS‡, of both the hydrolysis and ethanolysis reactions were determined using the Eyring equation and the activation parameters confirm the associative nature in the elementary steps in these reactions. Finally, it is shown that the dominant synthetic pathway in this triangular system changes from direct hydrolysis of methyl 4-hydrozybenzoate to the indirect pathway via ethanolysis and then hydrolysis depending on the solvent mixture composition.

Physicochemical and structural characteristics of chitosan nanopowders prepared by ultrafine milling

Two different molecular weights of chitosan were pulverized to nanopowders by ultrafine milling. The nanopowders were characterized by viscometry small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), FT-IR spectroscopy and UV-vis spectroscopy. Our results showed that ultrafine milling effectively reduced the particle size of chitosan to a nanoscale. The viscosity average molecular weight (Mv) of chitosan was decreased by the milling treatment. The crystalline structure of chitosan was destroyed by the milling since the nanopowder exhibited an amorphous XRD pattern. In addition, thermal stability of the low molecular weight chitosan was decreased after the milling treatment. FT-IR and UV-vis spectra showed that the milling process did not cause significant changes in the chemical structure of chitosan.

Bifunctional Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>@Eu-Polyoxometalates Nanoparticles and Study on their Magnetism and Luminescence

In this paper, we report the synthesis of the bifunctional Fe3O4@SiO2@Eu-polyoxometalates particles. The magnetite nanoparticles (Fe3O4) homogeneously coated with silica spheres prepared with the Stöber method. The so-obtained Fe3O4@SiO2 core/shell particles were modified by 3-aminopropyltriethoxysilane and finally grafted with the luminescent Europium -polyoxometalates. The core-shell particles were characterized by scanning electron microscopy, transmission electron microscopy, FT-IR, UV, magnetism and luminescence spectroscopy. The results indicated that the core-shell particles show both interesting luminescence and magnetic properties.

Synthesis and spectroscopic studies of stable aqueous dispersion of silver nanoparticles

A facile approach for the synthesis of stable aqueous dispersion of silver nanoparticles (AgNPs) using glucose as the reducing agent in water/micelles system, in which cetyltrimethylammonium bromide (CTAB) was used as capping agent (stabilizer) is described. The evolution of plasmon band of AgNPs was monitored under different conditions such as (a) concentration of sodium hydroxide, (b) concentration of glucose, (c) concentration of silver nitrate (d) concentration of CTAB, and (e) reaction time. AgNPs were characterized by UV–visible spectroscopy, transmission electron microscopy (TEM), fluorescence spectroscopy and FT-IR spectroscopy. The results revealed an easy and viable strategy for obtaining stable aqueous dispersion of AgNPs with well controlled shape and size below 30 nm in diameter.

Synthesis and study of cerium(IV) polytungstate nanolayers

For the first time the conditions for the synthesis of cerium(IV) polytungstate nanolayers on the silicon surface by the method of ion layering were defined. The layers were studied by scanning electron microscopy, X-ray microanalysis and transmission FT-IR spectroscopy. The synthetized layer is shown to have a globular structure with the size of the globules in the range of 30–50 nm, with the ratio of cerium/tungsten atomic concentrations equal to 0.8.

Detection of biotin–avidin affinity binding by exploiting a self-referenced system composed of upconverting luminescent nanoparticles and gold nanoparticles

We demonstrate an affinity system based on the interaction of two types of nanoparticles. The first consists of upconverting luminescent NaYF4:Yb,Er nanoparticles (UCNPs) with a size of 40–100 nm, absorbing light in the infrared and showing luminescence at 521, 543 and at 657 nm. The second consists of (red) gold nanoparticles (Au-NPs) with a size of about 50 nm and capable of absorbing the green luminescence of the UCNPs. By labeling the UCNPs with avidin and the AuNPs with biotin we have established a model system for a self referenced affinity system applicable to sensing in biological samples. In the presence of avidin-modified UCNPs, the biotinylated Au-NPs can be detected in the range from 12 to 250 μg mL−1 by ratioing the intensity of the red (analyte-independent) emission to that of the green (analyte-dependent) emission band. The nanoparticles were characterized in terms of size and composition using transmission electron microscopy, thermogravimetry, and FTIR spectroscopy.

Characterization of nano-crystalline ZrO2 synthesized via reactive plasma processing

Abstract Nano-crystalline ZrO 2 powder has been synthesized via reactive plasma processing. The synthesized ZrO 2 powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and FTIR spectroscopy. The synthesized powder consists of a mixture of tetragonal and monoclinic phases of zirconia. Average crystallite size calculated from the XRD pattern shows that particles with crystallite size 20 nm or less than 20 nm are in tetragonal phase, whereas particles greater than 20 nm are in the monoclinic phase. TEM results show that particles have spherical morphology with maximum percentage of particles distributed in a narrow size from about 15 nm to 30 nm.

Effects of O3 and NO2 on the natural weathering of plasticized poly(vinyl chloride)

AbstractThe aim of this work was to study the natural aging of plasticized poly(vinyl chloride) (PVC) stabilized with epoxidized sunflower oil and Ca/Zn stearates. For that purpose, PVC samples were exposed in Algiers (hot Mediterranean climate) in two sites where the concentration of atmospheric pollutants (NO2 and O3) was known for 2 years. Site I contained NO2 and O3, and site II contained only NO2. Samples were taken off every four months and characterized (mechanical properties and chemical modifications). The results showed a drop in tensile properties and an increase in Shore D hardness. The UV–Visible spectra evidenced the formation of short polyenes. Chemical structures due to the degradation were evidenced by ATR and transmission FTIR spectroscopy. It was found that the combination of O3 and NO2 exerted the most deleterious effect. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers

Sulfur Dioxide Adsorption on ZnO Nanoparticles and Nanorods

ZnO nanomaterials, nanoparticles, and nanorods, have been synthesized over a wide range of sizes with relatively high yield (∼90–95%). The synthesis method allows for size control by varying the amount of water used and morphology control by varying the zinc precursor (zinc acetate for nanoparticles or zinc acetylacetonate for nanorods). These nanomaterials were analyzed with powder X-ray diffraction and attenuated total reflection FTIR spectroscopy. Sulfur dioxide adsorption on nanoparticles and nanorods of different size was then investigated using volumetric measurements, transmission FTIR spectroscopy, and X-ray photoelectron spectroscopy. Nanoparticles and nanorods of several different sizes were heated to 550 °C to remove surface-adsorbed organic ligands that remained after the synthesis prior to exposure to SO2. Spectroscopic analysis revealed the formation of several surface species, including sulfate, sulfite, sulfide, and weakly bound SO2. Quantifying surface speciation as well as the total amou...

Thin polymer film based rapid surface acoustic wave humidity sensors

Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of glass slides, were studied using transmission FTIR spectroscopy upon varying relative humidity (RH) from 2 to 70%. The obtained data revealed fast dynamics of water vapor adsorption–desorption with responses on the order of several seconds. Based on the fast FTIR signal intensity changes versus RH, it was proposed that a similar rapid response can be achieved for PVA and PVP coated SAW devices due to changes in mass-loading and film viscoelastic properties upon absorption of water vapor in the films. Sub-micron thickness films were spin-coated onto the surface of LiNbO 3 SAW substrates. Both PVA and PVP based humidity sensors revealed prompt reversible response to variations in humidity, although PVP-based device demonstrated better sensor parameters with total insertion loss variation of about 50 dB over the studied RH range and response time 1.5 s for the humidity step 5–95% (recovery time – 2.5 s), representing one of the fastest SAW-based humidity sensors reported to date.

Existence of optical phonons in the room temperature ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate

The technologically important properties of room temperature ionic liquids (RTILs) are fundamentally linked to the ion-ion interactions present among the constituent ions. These ion-ion interactions in one RTIL (1-ethyl-3-methylimidazolium trifluoromethanesulfonate, [C(2)mim]CF(3)SO(3)) are characterized with transmission FTIR spectroscopy and polarized attenuated total reflection (ATR) FTIR spectroscopy. A quasilattice model is determined to be the best framework for understanding the ionic interactions. A novel spectroscopic approach is proposed to characterize the degree of order that is present in the quasilattice by comparing the dipole moment derivative calculated from two independent spectroscopic measurements: (1) the TO-LO splitting of a vibrational mode using dipolar coupling theory and (2) the optical constants of the material derived from polarized ATR experiments. In principle, dipole moment derivatives calculated from dipolar coupling theory should be similar to those calculated from the optical constants if the quasilattice of the RTIL is highly structured. However, a significant disparity for the two calculations is noted for [C(2)mim]CF(3)SO(3), indicating that the quasilattice of [C(2)mim]CF(3)SO(3) is somewhat disorganized. The potential ability to spectroscopically characterize the structure of the quasilattice, which governs the long-range ion-ion interactions in a RTIL, is a major step forward in understanding the interrelationship between the molecular-level interactions among the constituent ions of an ionic liquid and the important physical properties of the RTIL.

Synthesis and characterization of brush-like ZnO nanorods using albumen as biotemplate

Crystalline ZnO nanorods with wurtzite-like structure and average diameter of 90 nm and length >1 µm, was prepared by calcination (700 ºC) of a Zn(II)/albumen hybrid obtained by sol-gel method, by the reaction of Zn(II) acetate and egg white (albumen), in aqueous solution. The material was characterized by powder X-ray diffraction (XRD), scanning electron (SEM) and transmission electron microscopy (TEM), thermogravimetric analysis (TGA/DTA), N2 adsorption/desorption (BET method), FT-IR and photoluminescence (PL) spectroscopy. The surface area was determined to be 6.91 m² g-1 by BET method. The TGA/DTA thermal events were consistent with the decomposition of albumen at 300 ºC and final formation of ZnO at 578.5 ºC. The results showed that albumen act as template playing essential role on defining the formation of ZnO nanorods with brush-like morphology.

Reactive Adsorption of NO2 at Ambient Conditions on Iron‐Containing Polymer‐Based Porous Carbons

Adsorption of NO(2) and retention of NO (the product of NO(2) reduction by carbon) on iron-containing materials prepared from polystyrenesulfonic acid-co-maleic acid iron salt were studied. The surface of the materials was characterized using nitrogen adsorption, XRD, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and FTIR spectroscopy, and thermogravimetric analysis (TGA). The results showed the positive effects of the pore volume and well-dispersed iron species (Fe(2)O(3), FeSO(4), and FeS) on the performance of carbons as NO(2) adsorbents at room temperature. The retention of NO(2) on the carbon surface takes place either through its reduction to NO by carbon and/or by Fe(2)O(3), FeSO(4), and FeS, or through its reaction with Fe(2)O(3) and/or Fe(OH)(3), leading to the formation of Fe(NO(3))(3). The retention of NO is enhanced on carbons containing iron in the form of α-FeOOH, α-Fe(2)O(3), or γ-FeOOH. The best performance was found on the carbon with α-Fe(2)O(3). Dispersion and the particle size of iron compounds on the carbon surface affect both the adsorption/reduction process of NO(2) and the retention process of NO.

Direct synthesis and stabilization of Bi-sized cysteine-derived gold nanoparticles: Reduction catalyst for methylene blue

Bi-sized and separable gold nanoparticles (AuNps) with smaller sizes were synthesized by treatment of cysteine with tetrachloroauric acid solution. These nanoparticles were made stable with further reduction in size after adding very small volume of NaOH solution before controlled heating. In NaOH treated solution the AuNps stopped precipitation as compared to untreated solution. Various methods such as UV-Vis spectroscopy, Transmission Electron Microscopy (TEM), X-ray Diffractometry (XRD), FTIR and Raman spectroscopy were used for characterization of surface properties and interaction between AuNps and cysteine. The results showed good correlation with literature regarding the interaction but interesting differences in size distribution as evident from high resolution TEM micrograph. Zeta potential studies revealed that these particles are negatively charged. Surprisingly, the Raman of the cysteine-derived AuNps without NaOH showed tremendous enhancement as compared to pure cysteine and cysteine-derived AuNps treated with NaOH. The NaOH treated Cyst-AuNps sol proved as excellent homogeneous catalyst for reduction of methylene blue (MB).