Uniform α-Fe2O3 nanotubes fabricated for adsorption and photocatalytic oxidation of naphthalene

Uniform α-Fe₂O₃ nanotubes with small aspect ratio were successfully fabricated by a hydrothermal method. In situ Fourier-transform infrared spectroscopy was used to study the mechanistic details of adsorption and photocatalytic oxidation of naphthalene over theα-Fe₂O₃ nanotubes. A possible degradation mechanism of naphthalene was proposed.     

Acrylamide assisted polymeric citrate route for the synthesis of nanocrystalline ZrO2 powder

Nanocrystalline ZrO₂ powders have been prepared using acrylamide assisted polymeric citrate combustion (autoignition) route. Process parameters (i.e., total metal ions to citric acid ratio) were varied for the formation of polymeric resin in order to obtain the final product with desired properties (organic free, smaller crystallite size, etc.). The effect of three different citric acid amounts in the formation of nanocrystalline ZrO₂ powder was investigated using FTIR, XRD, TG/DTA and SEM-EDS, respectively, to identify the structural coordination, phase, thermal behavior and microstructure of the polymeric intermediates as well as the final ZrO₂ powders. Organic free ZrO₂ powder with two different phases of metastable t-ZrO₂ and m-ZrO₂ were prepared by calcining the polymeric intermediates at 600 °C. The lowest crystallite was found to be 18 and 16 nm, respectively, for the t-ZrO₂ and m-ZrO₂ phases prepared with total metal ions to citric acid ratio of 1:3.     

Synthesis and characterization of a lamellar hydroxyapatite/DNA nanohybrid

Two-dimensional layered materials exhibit desired functionalities when being used as gene delivery materials. In this study, a novel gene delivering vector, lamellar hydroxyapatite (HAp)/DNA nanohybrid was prepared. The structure of HAp/DNA nanohybrid was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared (FT-IR) spectroscopy analysis revealed that ion-exchange occurred during the process. Gel electrophoresis analysis confirmed that the lamellar HAp could protect DNA from degradation of DNase I and the protected DNA could be recovered readily under acid conditions. Furthermore, the integrity of released DNA was confirmed by UV–vis spectra.     

Studies of interaction of amines with TOPO/TOP capped CdSe quantum dots: Role of crystallite size and oxidation potential

This work reports the interaction of aliphatic (triethyl amine, butyl amine) and aromatic amines (PPD, aniline) with CdSe quantum dots of varied sizes. The emission properties and lifetime values of CdSe quantum dots were found to be dependent on the oxidation potential of amines and crystallite sizes. Smaller CdSe quantum dots (size 5 nm) ensure better surface coverage of amines and hence higher quenching efficiency of amines could be realized as compared to larger CdSe quantum dots (size 14 nm). Heterogeneous quenching of amines due to the presence of accessible and inaccessible set of CdSe fluorophores is indicated. PPD owing to its lowest oxidation potential (0.26 V) has been found to have higher quenching efficiency as compared to other amines TEA and aniline having oxidation potentials 0.66 and >1.0 V, respectively. Butyl amine on the other hand, plays a dual role: its post-addition acts as a quencher for smaller and enhances emission for larger CdSe quantum dots, respectively. The beneficial effect of butyl amine in enhancing emission intensity could be attributed to enhance capping effect and better passivation of surface-traps.     

Ag@graphene oxide nanocomposite as an efficient visible-light plasmonic photocatalyst for the degradation of organic pollutants: A facile green synthetic approach

We report a simple and effective supercritical route to decorate silver nanoparticles (Ag NPs) on graphene oxide (GO) using a commonly available and non-toxic glucose as a reducing agent. Transmission electron microscopy and energy-dispersive X-ray analysis confirmed that Ag NPs of size around 8–20 nm were coated on the GO surface under optimized experimental condition. Ag NPs on the GO surface were predominantly spherical in shape and well dispersed. The experimental results proved that the as-synthesized GO/Ag nanocomposite could be used as a highly efficient photocatalyst for the degradation of Rhodamine 123 dye and acetaldehyde under visible-light irradiation. The degradation results indicated that the photocatalytic performance of nanocomposite was greatly enhanced owing to the improved adsorption performance and separation efficiency of photo-generated carriers. The nanocomposite maintains a high level activity even after four times of recycle. Furthermore, the nanocomposite exhibited excellent antibacterial activity against gram-positive and gram-negative microorganisms.     

The effect of the presence of Ag nanoparticles on the photocatalytic degradation of oxalic acid adsorbed on TiO2 nanoparticles monitored by ATR-FTIR

Photocatalytic degradation of oxalic acid adsorbed on the Ag/P25 TiO₂ composite nanoparticle films were investigated using ATR-FTIR technique under UV irradiation. Ag/P25 TiO₂ composite nanoparticle films with various Ag content were tested. Topography and chemical structure/composition of the composite nanoparticle films were analyzed by AFM and XPS respectively. It was found that in the degradation reaction of the oxalic acid, the presence of only 2% Ag nanoparticles leads to six times more oxalic acid degradation compared to that degraded in the presence of pure P25 TiO₂ nanoparticles. The degradation rate of the oxalic acid is three times higher in the case of Ag/TiO₂ composite nanoparticle film than in the case of pure TiO₂ nanoparticles. It was observed that both the rate of oxalic acid degradation and the degraded amount of the oxalic acid were significantly affected by Ag incorporation.     

Ethyl acetoacetate ligand distribution in the course of titanium n-butoxide chelation

Sols obtained by chelation of titanium n-butoxide with ethyl acetoacetate, Eaa, in various ratios have been subjected to FTIR, ¹H and ¹³C NMR, HSQC and UV–Vis spectroscopy in order to provide insight in the compounds obtained, their structure and quantitative relationships. Three compounds, the bis-chelated monomer, Ti(OⁿBu)₂(Eaa)₂, bis-chelated dimer, (Ti(OⁿBu)₃Eaa)₂ and monochelated dimer, Ti₂(OⁿBu)₇Eaa have been established. As the molar ratio Eaa/Ti(OⁿBu)₄ increases, the coordination changes from the monochelated and bis-chelated dimer to the bis-chelated monomer. Additionally, the transesterification reaction, influencing the chemical composition of the compounds was noted. The hydrolysis of the prepared sols was partial, leaving some residual butoxy and ethyl acetoacetate groups attached to titanium. Thermal treatment of the prepared amorphous gels at 350 °C yielded with the formation of nanocrystalline anatase. It was noted that high Eaa/Tnb ratio slightly retards the anatase formation.     

An IR and XPS spectroscopy assessment of the physico-chemical surface properties of alumina–YAG nanopowders

Well-dispersed nano-crystalline transition alumina suspensions were mixed with yttrium chloride aqueous solutions, with the aim of producing by spray-drying Al₂O₃–Y₃Al₅O₁₂ (YAG) composite powders of increasing YAG vol.%. Two samples were prepared, with different Y content, corresponding to 5 and 20 YAG vol.%, respectively. Both samples were then treated at either 600 or 1150 °C. The obtained powders were characterized by X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infra Red (FT-IR) spectroscopy and compared to three reference samples: commercial nano-crystalline transition alumina, YAG and Y₂O₃. YAG powders were obtained by co-precipitation route whereas Y₂O₃ powders were yielded by spray-drying of a yttrium chloride aqueous solution. Modification of physico-chemical properties of the surface of alumina nanoparticles were assessed by combining XPS and FT-IR spectroscopies. On the basis of the results obtained, a possible model is proposed for the structure of the obtained composites, in which Y basically reacts with more acidic hydroxyls of alumina, by forming Y-rich surface grains, the extension of which depends on the thermal treatment.     

Investigation of irradiated graphene oxide/ultra-high-molecular-weight polyethylene nanocomposites by ESR and FTIR spectroscopy

Graphene oxide/ultra-high-molecular-weight polyethylene (GO/UHMWPE) nanocomposite has a potential application for artificial joints. However, free radicals and antioxidative properties of irradiated GO/UHMWPE were not clearly clarified. In this paper, GO/UHMWPE nanocomposites were prepared and irradiated by gamma-irradiation with a dose of 100 kGy. Afterward, test samples were aged in air. Free radicals and molecular structures of test samples were investigated by electron spin resonance (ESR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy, respectively. These studies indicated that irradiation enhanced GO radical concentrations. And GO radicals were stable in air and even could not be quenched after accelerated aging. GO radicals were superimposed on free radicals of irradiated UHMWPE. Although GO showed free radical-scavenging capacity, the influence of GO on free radicals of irradiated UHMWPE was too weak to be observed in ESR spectroscopy. Free radicals concentrations of irradiated GO/UHMWPE nanocomposites were gradually decayed with aging time evolving in air. Observing the oxidation index values of test samples, it was proposed that irradiated GO/UHMWPE might show very weak antioxidative properties.     

The formation of a SiOx interfacial layer on low-k SiOCH materials fabricated in ULSI application

The characterizations of SiOCH films using oxygen plasma treatment depends linearly on the O₂/CO flow rate ratio. According to the results of Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses, it was found that the carbon composition decreases with increasing O₂/CO flow rate ratio, because more carbon in the Si–O–C and Si–CH₃ bonds on the film surface would be converted by oxygen radicals. It was believed that the oxygen plasma could oxidize the SiOCH films and form a SiO_x interfacial capping layer without much porosity. Moreover, the result of FTIR analysis revealed that there was no water absorbed on the film. A SiO₂-like capping layer formed at the SiOCH film by the O₂/CO flow rate ratio of 0.75 had nearly the same dielectric properties from the result of capacitance–voltage (C–V) measurement in our research.     

Polyaniline/Vanadium oxide composites: An effective control in morphology by varying reactant concentrations

A one pot synthesis protocol is presented for the realization of organic/inorganic hybrid nanostructures comprised of polyaniline and vanadium oxide. The polyaniline/vanadium oxide hybrid morphology is tailored by controlling the relative concentration of reactants which resulted in diverse morphologies ranging from nanorods, combined nano/microrods to porous nano/microspheres. Temporal evolution of morphology is investigated to elucidate the formation mechanism in detail. The prepared composites exhibit enhanced thermal stability in comparison to pure polyaniline which may be attributed to the strong chemical combination of vanadium oxide and polyaniline within the composites as prevailed by FTIR and TGA analysis of the products. This simple and controllable approach for synthesizing the organic/inorganic hybrid material should have future applications in energy storage devices, sensors and many more.     

Effects of oxygen percentage on the growth of copper oxide thin films by reactive radio frequency sputtering

Copper oxide thin films were deposited onto glass substrates by reactive radio frequency magnetron sputtering at various oxygen percentage flow rates R(O₂). X-ray diffraction analysis revealed that nanocrystallite copper oxide thin films with cubic, tetragonal, and monoclinic structure were formed at R(O₂) values of 10%, 20%, and ≥30%, respectively. Energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy were used to verify the copper oxides phases. With increased R(O₂), the root mean square surface roughness of the deposited films decreased from 4.82 nm to 1.78 nm. Moreover, both the band gap type and value changed with increased R(O₂). For R(O₂) at 20%, single phase tetragonal Cu₄O₃ thin film with a direct band gap of 2.20 eV was formed. For R(O₂) ≥ 30%, single phase monoclinic CuO thin films with an indirect band gap of 1.20 eV–1.25 eV were formed. In addition, conductive copper oxide thin films tended to form for R(O₂) < 30%, whereas insulator oxide thin films tended to form for R(O₂) ≥ 30%. Through this study, the crystallization behavior, the band gap, and the resistivity properties of the deposited copper oxide thin films as a function of the R(O₂) were obtained.     

Bio-templated CdSe quantum dots green synthesis in the functional protein,lysozyme, and biological activity investigation

Bifunctional fluorescence (CdSe Quantum Dots) – protein (Lysozyme) nanocomposites were synthesized at room temperature by a protein-directed, solution-phase, green-synthetic method. Fluorescence (FL) and absorption spectra showed that CdSe QDs were prepared successfully with Lyz. The average particle size and crystalline structure of QDs were investigated by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD), respectively. With attenuated total reflection-fourier transform infrared (ATR-FTIR) spectra and thermogravimetric (TG) analysis, it was confirmed that there is interaction between QDs and amide I, amide II groups in Lyz. FL polarization was measured and FL imaging was done to monitor whether QDs could be responsible for possible changes in the conformation and activity of Lyz. Interestingly, the results showed Lyz still retain the biological activity after formation of QDs, but the secondary structure of the Lyz was changed. And the advantage of this synthesis method is producing excellent fluorescent QDs with specifically biological function.     

Synthesis of carbon nitride powder by selective etching of TiC0.3N0.7 in chlorine-containing atmosphere at moderate temperature

We reported the synthesis of carbon nitride powder by extracting titanium from single inorganic precursor TiC_0.3N_0.7 in chlorine-containing atmosphere at ambient pressure and temperature not exceeding 500 °C. The TiC_0.3N_0.7 crystalline structure acted as a template, supplying active carbon and nitrogen atoms for carbon nitride when it was destroyed in chlorination. X-ray diffraction data showed that the obtained carbon nitride powders were amorphous, which was in good agreement with transmission electron microscope analysis. The composition and structure of carbon nitride powders were analyzed by employing Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Results indicated that disorder structure was most likely for the carbon nitride powders and the N content depended greatly on the chlorination temperature. Thermal analysis in flowing N₂ indicated that the mass loss started from 300 °C and the complete decomposition occurred at around 650 °C, confirming the low thermal stability of the carbon nitride material.     

Investigation of kinetics and morphology development for polyurethane-urea extended by DMTDA

The relationship between the reactions kinetics and morphology development during the polyurethaneurea (PUU) curing process has been investigated simultaneously by in situ Fourier transform infrared spectroscopy (FTIR). The data of the FTIR spectra showed that with the increase of conversion, the absorbance of NH bands increases and its band sites shifts to lower wavenumbers; the absorbance of free urethane carbonyl kept nearly constant at low conversion, and then decreased much because of the interaction of the formed urea links, and then changed little at high conversion owing to the diffuse control. The band sites of hydrogen bonded urea carbonyl similarly shifted to lower wavenumbers and the absorbance of the hydrogen bonded urea carbonyl, associated with the phase separation of hard segments, became stronger with buildup of hydrogen bond between urea links. The carbonyl bands available during curing process were further assigned. Both interactions, such as hydrogenised effect and phase separation, played a major role in the matrix formation of the PUU polymer.     

Synthesis,characterization and flocculation activity of novel Fe(OH)3–polyacrylamide hybrid polymer

A novel Fe(OH)₃–polyacrylamide inorganic–organic hybrid polymer (FHPAM) was synthesized via free radical solution polymerization initiated by a redox initiation system ((NH₄)₂S₂O₈–NaHSO₃) in an aqueous medium. Reaction parameters influencing the intrinsic viscosity and the yield of the hybrid polymer, such as initiator concentration, monomer mass fraction, temperature and reaction time were investigated and optimized. The results show that the maximum intrinsic viscosity and up to 94% yields of the hybrid polymer can be achieved using initiator concentration of 0.3% with acrylamide monomer mass fraction of 20% under solution polymerization at 40 °C for 7 h. The physicochemical properties of this hybrid flocculant were characterized with TEM, FTIR spectra, TGA, and conductivity. It was found that a chemical bond exists between Fe(OH)₃ colloid and polyacrylamide chains in the FHPAM. The application of the hybrid polymer for the treatment of 2.5 g L⁻¹ kaolin suspension indicates that it had an excellent flocculation capacity and its flocculation efficiency was much better than that of commercial available polyacrylamide (PAM) and polymeric ferric sulfate (PFS). The optimal conditions for the flocculation treatment of kaolin suspension were the FHPAM dosage of 40 mg L⁻¹ at pH 7.0. The thermodynamic parameters for the flocculation process were calculated based on a statistical model. Interpretation of the results was given.     

Synthesis and super capacitance of goethite/reduced graphene oxide for supercapacitors

We report a one-step fabrication of α-iron oxyhydroxide/reduced graphene oxide (α-FeOOH/rGO) composites, in which the ferrous sulfate (FeSO₄·7H₂O) are used as the iron raw and reducing agent to grow goethite (α-FeOOH) and reduce graphite oxide (GO) to rGO in the same time. The morphology, composition and microstructure of the as-obtained samples are systematically characterized by thermogravimetric (TG) analysis, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and FT-IR. Moreover, their electrochemical properties are investigated using cyclic voltammetry and galvanostatic charge/discharge techniques. The specific capacitance of 452 F g⁻¹ is obtained at a specific current of 1 A g⁻¹ when the mass ratio of α-FeOOH to rGO is up to 80.3:19.7. In addition, the α-FeOOH/rGO composite electrodes exhibit the excellent rate capability (more than 79% retention at 10 A g⁻¹ relative to 1 A g⁻¹) and well cycling stability (13% capacitance decay after 1000 cycles). These results suggest the importance and great potential of α-FeOOH/rGO composites in the applications of high-performance energy-storage.     

Encapsulation of ferro- and ferricyanide complexes inside ZSM-5 zeolite synthesized from rice straw: Implications for synthesis of Prussian blue pigment

Encapsulation of [Fe(CN)₆]⁴⁻ and [Fe(CN)₆]³⁻ complexes in the intracrystalline pores of ZSM-5 zeolite, Fe^IIL/Z and Fe^IIIL/Z respectively, by the zeolite synthesis method was reported. The modified zeolites were characterized by powder XRD, FT-IR and UV–vis spectroscopy. The nitrogen adsorption isotherms allow for the evaluation of pore structure of the complex-modified zeolites, whereas the thermal analysis (TGA/DTA) measurements provide insight into the decomposition products of the immobilized complexes. The modified zeolites exhibited smaller pore volumes and surface areas as compared with those of unpromoted ZSM-5, suggesting the inclusion of iron cyanides inside the interconnecting channels of ZSM-5. While the ferricyanide complex enhanced the formation of highly crystalline zeolite, the ferrocyanide one resulted in a lesser effect. The electronic spectra of the colloidal species developed when Fe^IIIL/Z brought in contact with an aqueous solution of [Fe(CN)₆]³⁻ exhibit absorptions attributed to CN⁻ → iron charge-transfer. New bands at 294 and 319 nm due to d–d transitions of Fe^III tetrahedral monomeric moieties were emitted concurrently under successive adsorption of _[Fe₍CN_)6]aq³⁻${{\left[\text{Fe}{\left(\text{CN}\right)}_6\right]}_{\text{aq}}}^{3-}$ over Fe^IIIL/Z, along with a broad band at 555 nm assigned to polymeric [Fe^II–C–N–Fe^III] of Prussian blue (PB). The FT-IR spectra of Fe^III/IIL/Z devoted to the adsorption of an aqueous solution of [Fe(CN)₆]³⁻ showed a band at 2092 cm⁻¹ assigned to the C–N stretch in the Fe^II–CN–Fe^III linkages. The vibrations attributable to Fe–O–Si bonding along with hydrocarbon and nitroprusside appeared only in the spectrum of Fe^IIIL/Z, thus was found to be strong evidence for the mutual interaction between [Fe(CN)₆]³⁻ and the latter sample.     

The effect of chelating/combustion agent on catalytic activity and magnetic properties of Dy doped Ni–Zn ferrite

The spinel ferrite Ni_0.8Zn_0.2Fe_1.98Dy_0.02O₄ was prepared by sol–gel low temperature autocombustion method using four different chelating/combustion agents: citric acid, tartaric acid, urea and cellulose. Infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) specific surface area measurement, the catalytic H₂O₂ decomposition and the magnetic behavior were employed to investigate the influence of the combustion agents on structural characteristics, catalytic activity and magnetic properties. Spinel-type phase in the nano-scale domain was accomplished during sol–gel synthesis and was confirmed by XRD and IR. The best catalytic activity is belonging to the sample obtained using urea, which shows the smallest grain size (SEM), the highest specific surface area (BET measurements) and DyFeO₃ phase (XRD), while ferrimagnetic behavior prevails for all the samples independently of fuel agent.     

Synthesis,crystal growth,thermal studies and scaled quantum chemical studies of structural and vibrational spectra of the highly efficient organic NLO crystal: 1-(4-Aminophenyl)-3-(3,4-dimethoxyphenyl)-prop-2-en-1-one

A new chalcone derivative, 1-(4-aminophenyl)-3-(3,4-dimethoxyphenyl)-prop-2-en-1-one (DMAC) was synthesized and single crystals were grown by slow evaporation technique. The FT-Raman and FT-IR spectra of the sample were recorded in the region 3700–100 cm⁻¹ and 4000–400 cm⁻¹, respectively. The spectra were interpreted with the aid of normal coordinate analysis following structure optimizations and force field calculations based on density functional theory (DFT) at the B3LYP/6-311+G(d,p) level of theory. Normal coordinate calculations were performed using the DFT force field, corrected by a recommended set of scaling factors, yielding fairly good agreement between the observed and calculated wavenumbers. DMAC is thermally stable up to 220.0 °C and optically transparent in the visible region. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with electrostatic potential surfaces (ESP). The SHG efficiency of DMAC is observed to be 10 times that of standard urea crystal of identical particle size.