The current work demonstrates the first reported successful synthesis of unique alpha-TeO2 hybrid microstructures through thermal oxidation of Te microtubes in a horizontal tube furnace at different temperatures in the range 220-470 degrees C, under oxygen flow. The obtained microstructures were carefully characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy. They exhibited characteristic morphologies with porous scaffold microtubes covered along their whole length with pearl-like microwires. The possible formation mechanism of the obtained microstructures was also discussed.

GaS single crystal layers have been thermally treated under argon flow for 4 h at two different temperatures (700 degrees C and 900 degrees C). The starting GaS sample and the annealed ones have been characterized by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy. It was found that GaS transformed into beta-Ga2S3 through the formation of Ga2S3 intermediate phase. Moreover, such an oxidation process involved the growth of dense Ga2S3 sub-micron crystallites at a temperature of 700 degrees C and relatively long beta-Ga2S3 nanowires (up to 4 mu m) at a temperature of 900 degrees C. Experiments also evidenced that an intentional supply of oxygen was unfavourable both to the formation of Ga2S3 phase and to the growth of sub-micron crystallites and nanowires.

In this paper, we report the obtention of In2O3 nanostructured microwires by the decomposition thermal treatment of InSe single crystal in two-steps under an oxygen-ammonia flow without the presence of any catalyst. Long In2O3 microwires with uniform shape and homogeneous surface were first synthesized through thermal treatment of InSe single crystal at temperature of about 640 degrees C; then, furnace temperature was increased to 750 degrees C and, as annealing time proceeded, the obtained microwires served as substrates on which nanorod branches grew. The shape and the structure of the microarchitectures were characterized by means scanning electron microscopy, transmission electron microscopy, selected area diffraction pattern, X-Ray diffraction and Raman spectroscopy. Our results indicated that In2O3 primary wires with a clean surface grew in the [100] direction and that the secondary protuberances grew in the [011] direction. A possible growth mechanism of the hierarchical microwires was also proposed. (C) 2012 Elsevier B.V. All rights reserved.

In this work the results of the thermal oxidation of GaSe thin films in air at different temperatures are presented. The structural and morphological characteristics of the thermally annealed products were studied by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The as-deposited GaSe films were amorphous and they transformed into polycrystalline GaSe films with a hexagonal crystal structure at a temperature around 400°C. Thermal oxidation at 650°C resulted in the formation of mixed Ga2Se3 and Ga2O3compounds both in the monoclinic phase. At higher temperatures, Ga2Se 3 disappeared and complete oxidation of the initial compound occurred. The optical energy gaps of products were determined at room temperature by transmittance measurements using UV-vis-NIR spectroscopy.

A non-enzymatic amperometric sensor for glucose detection based on a Pt electrodemodified with Te microtubes (Te-MTs), by direct drop casting of Te-MTs dispersed in ethanol, is proposed. The spectroscopic characterization of as synthesized Te-MTs and Pt/Te-MTsmodified electrodes was performed by scanning electronmicroscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Moreover electrochemical characterization of Pt/Te-MTs modified electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH=7 I=0.2). Electrochemical results indicate that the proposed sensor exhibits very strong and sensitive amperometric responses to glucose and explains a good anti-interference ability.

Mass concentrations of PM2.5, mineral dust, organic carbon (OC) and elemental carbon (EC), water-soluble organic carbon (WSOC), sea salts and anthropogenic metals have been studied in a city-port of south Italy (Brindisi). This city is characterized by different emission sources (ship, vehicular traffic, biomass burning and industrial emissions) and it is an important port and industrial site of the Adriatic sea. Based on diagnostic ratios of carbonaceous species we assess the presence of biomass burning emissions (BBE), fossil fuel emissions (FFE) and ship emission (SE). Our proposed conversion factors from OC to OM are higher than those reported in the literature for urban site: the reason of this could be due to the existence of aged combustion aerosols during the sampling campaign (WSOC/OC = 0.6 ± 0.3).

The present work describes the preparation and the characterization of a composite nanomaterial obtained by the electrochemical deposition of copper nanoparticles (CuNPs) on an electrosynthesized film of poly-3-methylthiophene (P3MT). Copper electrodeposition was achieved by applying a potential pulse program both on Pt and on screen-printed electrodes (SPEs). The microscopic characterization of the composite film by scanning electron microscopy (SEM) suggested that the applied pulse width is correlated to the amount of the deposited particles but it does not influence CuNPs size. The nanocomposite was analyzed also by X-ray Photoelectron Spectroscopy (XPS) confirming the influence of the pulse width on the amount of electrodeposited copper and evidencing the presence of Cu(I) and Cu(II) species in each sample. For a comparison, CuNPs were prepared from solutions of both CuCl2 and Cu(ClO4)2. XPS analysis evidenced the stabilizing effect of Cl− ions on CuNPs promoting their entrapment in P3MT film also when the composite film is exposed to carrier solution in a flow system, contrarily to what observed in the presence of ClO4− ions. Performed electrochemical tests showed that CuNPs/P3MT exhibited a remarkable electrocatalytic activity for glucose oxidation. The composite film deposited on SPEs was successfully used for glucose electrochemical detection in a flow system. The effect of the applied potential and of the flow rate of carrier stream was evaluated: under the selected optimal condition the composite film exhibited a satisfactory response in terms of detection limit, linear range and repeatability. The sensitivity of CuNPs/P3MT to other compounds (ascorbic acid, uric acid, sorbitol, fructose, dopamine) was verified evidencing that the proposed system could be effectively used as an electrochemical detector coupled to a chromatographic system for the simultaneous detection of biomolecules.

Long α-TeO2 microwires were synthesized in high yield on quartz substrate by vapor transport process, using Te powder as the source material and oxygen (O2) as a carrier gas. Scanning electron microscope (SEM), X-Ray diffraction (XRD), transmission electron microscopy (TEM) and selected area diffraction patterns (SAD) were employed to characterize the microstructures obtained at different growth time steps in order to propose a possible growth mechanism of microwires. Irregular microparticles were first formed on the quartz substrate surface and then they acted as self-catalytic center for the growth of smooth microwires with diameters in the range 2–4 μm and lengths up to 300 μm. As heating time proceeded, the surface of the microwires was gradually covered by microparticles, till they covered the wires along their whole length. Interestingly, microwires with a segmented morphology were also observed.

In2O3 microrods were grown by thermal oxidation of InSe single crystal under a mixture of argon−oxygen flow without the presence of a catalyst. Microrods were obtained at the temperature of about 640 °C after a thermal treatment of 180 min. The morphology, structure, and composition of the prepared materials were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction spectroscopy (XRD). The microrods had a hexagonal cross-section with a diameter range of 1−3 μm and a length of between 20 and 30 μm. Structural analysis showed that the microstructures were cubic In2O3 crystal with a lattice constant of a = 10.115 Å. The possible mechanism of the formation of In2O3 microstructures is also discussed in this work

In this work a new original amperometric sensor forH2O2 detection based on a Pt electrode modified with Te-microtubes was developed. Te-microtubes, synthesized by the simple thermal evaporation of Te powder, have a tubular structure with a hexagonal cross-section and are open ended. Modified electrode was prepared by direct drop casting of the mixture of Te-microtubes dispersed in ethanol on Pt surface. The spectroscopic characterization of synthesized Te-microtubes and Pt/Te-microtubes modified electrodes was performed by scanning electron microscopy (SEM), energy-dispersive X-rays microanalysis (EDX), X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS). Moreover a complete electrochemical characterization of the new composite material Pt/Te-microtubes was performed by cyclic voltammetry (CV) and cronoamperometry (CA) in phosphate buffer solution (PBS) at pH 7. Electrochemical experiments showed that the presence of Te-microtubes on modified electrode was responsible for an increment of both cathodic and anodic currents in presence of H2O2 with respect to bare Pt. Specifically, data collected from amperometric experiments at −150mV vs. SCE in batch and −200mV vs. SCE in flow injection analysis (FIA) experiments show a remarkable increment of the cathodic current. The electrochemical performances of tested sensors make them suitable for the quantitative determination of H2O2 substrate both in batch and in FIA.

Abstract Angström exponents (Å) and dust concentrations from the Barcelona Supercomputing Center-Dust REgional Atmospheric Model (BSC-DREAM) were used to infer the impact of long-range transported desert dust particles at the ground level and evaluate their role on the chemical composition of PM1 and PM10 samples. Å values were calculated from the scattering coefficients at 450 and 635 nm, retrieved from integrating nephelometer measurements. Nephelometer measurements were performed at a coastal site (Lecce, 40.33° N, 18.11° E) of south-eastern Italy from December 2011 till November 2012. Days characterized by Å daily mean values smaller than 0.95 and modelled daily dust concentrations larger than 0.1 μg m−3 at 86 m above the ground level were considered representative of days affected by African dust particles up to the ground level (dusty days). Both criteria have allowed identifying 86 dusty days during the investigated period. The analysis of 24-h simultaneously collected PM10 and PM1 samples revealed that the PM1 mass concentrations increased linearly with PM10 both in dusty and dustfree days, which were identified as the ones characterized by Å daily mean values larger than 1.3 and PM1/PM10 ratios larger than 0.35. These results suggested that the PM1 samples were also affected by desert particles on dusty days. In fact, chemical analyses revealed that the Al and Fe mean mass concentrations were larger in dusty day PM1 and PM10 samples. Then, we found that the crustal matter contribution was nearly twice and more than twice larger in dusty PM1 and PM10 samples, respectively, than in corresponding dust-free samples. Mass contributions of organic and elemental carbon, sulfates, and ammonium even if smaller in dusty samples than in dust-free PM1 and PM10 samples revealed the significant role of the anthropogenic pollution also on dusty days.

Background: Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied on PM10 particle data in order to: identify particle clusters that can be differentiated on the bases of their chemical composition and morphology, investigate the relationship among the chemical and morphological parameters and evaluate differences among the sampling sites. PM10 was collected in 3 different sites in central Italy characterized by different conditions: yard, urban and rural sites. The concentration of 20 chemical parameters (C, O, Na, Mg, Al, Si, P, Cd, Cl, K, Ca, Sn, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn) were determined by Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy (SEM-EDS) and the particle images were processed by an image analysis software in order to measure: Area, Aspect Ratio, Roundness, Fractal Dimension, Box Width, Box Height and Perimeter. Result: Results revealed the presence of different clusters of particles, differentiated on the bases of chemical composition and morphological parameters (aluminosilicates, calcium particles, biological particles, soot, cenosphere, sodium chloride, sulphates, metallic particles, iron spherical particles). Aluminosilicates and Calcium particles of rural and urban sites showed a similar nature due to a mainly natural origin, while those of the yard site showed a more heterogeneous composition mainly related to human activity. Biological particles and soot can be differentiated on the bases of the higher loads of Fractal Dimension, which characterizes soot, and content of Na, Mg, Ca, Cl and K which characterize the biological ones. The soot of the urban site showed higher loadings of Roundness and Fractal Dimension than the soot belonging to the yard and rural sites, this was due to the different life time of the particles. The metal particles, characterized mainly by the higher loading of iron, were present in two morphological forms: spherical and angular particles. The first were generated by a fusion process at high temperature, while the second one had crustal origin (those characterized by typical terrigenous elements) and also human origin. Conclusion: In this work a protocol for the morphological-chemical characterization of single particles has been developed. SEM analysis allows to classify particles in 10 different families and PCA and HCA have provided information about the sources of PM and similarities and differences among the sites.

Indium monoselenide (InSe) nanowires were grown by the thermal evaporation method in argon atmosphere without the presence of any catalysts using InSe polycrystalline powder as the source material. No nanostructure growth was observed at deposition temperatures below 580 °C. The nanostructures were discernable at temperatures above 620 °C. Pure InSe nanowires were obtained at the deposition temperature of 660 °C for 50 min. The diameters of the nanowires were from 50 to 240 nm and their lengths were up to several micrometers. X-ray diffraction spectrum reveals that the synthesized products were single-crystalline of the β-phase hexagonal structure of InSe with lattice constants a = 4.006 Å and c = 16.642 Å. The strong peak due to the reflection from the (004) crystal plane reveals that most nanowires grow with a strong preferred orientation

The synthesis of new β-Ga2O3 microstructures was achieved through rapid annealing of GaSe single crystal at 850 °C in oxygen-ammonia co-flow for 30-120 min duration. The obtained micro-flowers and micro-leaves were carefully characterized through X-ray diffraction, scanning electron microscopy and Raman spectroscopy. SEM images demonstrated that the product consisted of flower-shaped microstructures, which as time elapsed evolved into leaves-like dendritic microstructures. These microstructures started off directly from oxidized single crystal. A possible growth mechanism was also proposed. Experimental results evidenced that synthesized microstructures exhibited good photocatalytic activity, better than commercial TiO2 powder (Degussa P25).

ABSTRACT A new nonenzymatic platinum Te oxide nanowires modified electrode (Pt/TeO2-NWs) for amperometric detection of hydrogen peroxide (H2O2) is proposed. The modified electrode has been developed by direct drop casting, with TeO2 nanowires (TeO2-NWs), synthesized by thermal evaporation of Te(0) in an oxygen atmosphere. The morphological and spectroscopic characterization of the TeO2-NWs as synthesized on Pt foil was performed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. XPS and XRD analysis are especially involved to gain information on the chemical environment of TeO2-NWs in contact with Pt surface. Moreover electrochemical characterization of these new modified Pt/TeO2-NWs modified electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH = 7; I = 0.2) to investigate the sensing properties of this material against H2O2. The proposed sensor exhibits a wide linear and dynamic range from 2 μM to 16 mM (R2 = 0.9998) and the detection limit is estimated to be 0.6 μM (S/N = 3). Moreover, this sensor shows a rapid amperometric response time of less than 5 s and possessed good reproducibility. These results indicate that Pt/TeO2-NWs composite is suitable to be used as material for sensing applications.