2011


Valerini D.ab, Cretí A.c, Caricato A.P.b, Lomascolo M.c, Rella R.c, Martino M.b
(2011) Laser Beams: Theory, Properties and Applications, pp. 205-244
a Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Research Centre of Brindisi, S.S. 7 Appia - km 706, 72100 Brindisi, Italy
b Department of Physics, L3 group, University of Salento, Via Arnesano, 73100 Lecce, Italy
c IMM-CNR, Institute for Microelectronics and Microsystems, Department of Lecce, Via Arnesano, 73100 Lecce, Italy
Abstract
This chapter aims to present a brief review about a very interesting application of laser beams in the field of materials science: the growth of zinc oxide (ZnO) nanostructured films by Pulsed Laser Deposition (PLD), and in particular by means of excimer laser ablation. After an introduction giving an overview on properties and applications of ZnO and its nanostructures and on some growth techniques used to obtain these materials, this survey will present several results, obtained by different research groups in the world, about nanostructured ZnO grown by excimer laser ablation. Then this study will be focused on the results obtained by our research group in this field so far. By properly changing some deposition parameters (substrate temperature, oxygen pressure and ablation laser wavelength) we obtained nanostructured films with hexagonal pyramids, columns, hexagonal hierarchical structures and pencils, as well as smooth or rough films. In particular the different ablation laser wavelengths (248 nm of KrF and 193 nm of ArF) are shown to have a deep influence on both morphology and crystal quality of the grown samples. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and photoluminescence (PL) measurements were used to inspect the film properties. Finally, some results about our optical gas sensing tests conducted on the grown samples are presented. © 2011 by Nova Science Publishers, Inc. All rights reserved.
Document Type: Book Chapter
Source: Scopus

 

Altamura D.abd, Miccoli I.a, Prete P.c, Lovergine N.a, Tapfer L.b
(2011) Materials Research Society Symposium Proceedings, 1350, pp. 7-12
a Dipartimento di Ingegneria dell'Innovazione, Università del Salento, Via Monteroni, I-73100 Lecce, Italy
b ENEA, Unità Tecnica Tecnologia dei Materiali Brindisi (UTTMATB), S.S. 7 Appia km 706, I-72100 Brindisi, Italy
c Istituto Per la Microelettronica e Microsistemi (IMM), CNR, Via Monteroni, I-73100 Lecce, Italy
d Istituto di Cristallografia (IC), CNR, Via G. Amendola 122, I-70126 Bari, Italy
Abstract
In this work, we report on the microstructural and morphological characterization of III-V semiconductor nanowires (NWs) epitaxially grown on (111)B-GaAs substrates by Au-catalyst assisted metalorganic vapor phase epitaxy. As-grown dense (10 8-10 9 cm -2) arrays of few-micron long vertically-aligned (i.e. parallel to the 〈111〉 crystallographic axis) GaAs, Al xGa 1-xAs and core-shell GaAs-Al xGa 1-xAs NWs were investigated, carrying out HRXRD measurements on different (hkl) reflections and by recording reciprocal space maps (RSMs) around the materials (111) reciprocal lattice points (relps). We show that NW diffraction peaks are visible in the RSM by means of characteristic halos. In the case of GaAs NWs, the halo is located at the (111) relp indicating that the NWs are grown along the 〈111〉 direction and parallel to the 〈111〉 axis of the GaAs substrate. On the contrary, for Al xGa 1-xAs NWs or intentional core-shell GaAs-Al xGa 1-xAs NWs the halo is displaced (along the momentum transfer normal to the surface, Q z) with respect to the GaAs (111) relp due to the elastic lattice strain associated with the compositional variation, e.g. the Al molar fraction in the Al xGa 1-xAs alloy, within the nanostructures. © 2011 Materials Research Society.
Document Type: Conference Paper
Source: Scopus

 

Signore M.A.a , Sytchkova A.b , Rizzo A.a
(2011) Optical Materials, 34 (1), pp. 292-297.
a ENEA-Technical Unit Material Technology, Research Centre of Brindisi, S.S. 7 Appia km 706, 72100 Brindisi, Italy
b ENEA-Technical Unit Material Technology, Research Centre of Casaccia, Via Anguillarese 301, 00123 Rome, Italy
Abstract
In this paper the first results of a work concerned with the development of TiAlON selective solar absorbers with high solar absorptance and low thermal emittance are presented. These absorbers are thought for solar collectors application at operational temperature of about 300 °C. Solar absorber tandems, consisting of an absorbing TiAlON compound sputtered on a TiC buffer layer deposited on a metal (Cu) substrate, have been produced in two ways: by changing the nitrogen flux percentage in (Ar + N2 + O2) mixture at fixed thickness (300 nm) and by varying the absorber thickness at fixed nitrogen percentage (5%) in the sputtering gas. The optical response in the UV-IR range is discussed. The tuning of the nitrogen flux allows to change the metal elements ratio (Ti/Al) in the oxynitride layer, varying the reflectance intensity both in the IR and visible range. The thickness variation permits to shift the cut-off wavelength of the transition from short wavelength high absorptance to long wavelength low emittance. The tuning of these two parameters (nitrogen flux and absorber thickness) enables to control the optical response of the samples to make them suitable for photo-thermal device application. © 2011 Elsevier B.V. All rights reserved.
Author Keywords
RF magnetron sputtering; Solar absorbers; Titanium-aluminum oxynitride

Document Type: Article
Source: Scopus

 

Penza M.a, Suriano D.a, Cassano G.a, Rossi R.a, Alvisi M.a, Pfister V.a, Trizio L.b c , Brattoli M.bc, Amodio M.bc, De Gennaro G.b c
(2011) AIP Conference Proceedings, 1362, pp. 234-235.
a Brindisi Technical Unit of Technologies for Materials, ENEA-Italian National Agency for New Technologies, Energy and Sustainable Economic Development, SS 7 Appia Km 712, Brindisi, Italy
b Chemistry Department, University of Bari, via Orabona 4, Bari, Italy
c Lenviros Srl, Spin-off from University of Bari, via Orabona 4, Bari, Italy
Abstract
A portable sensor-system based on solid-state gas sensors has been designed and implemented as proof-of-concept for environmental air-monitoring applications, malodours olfactometric control and landfill gas monitoring. Commercial gas sensors and nanotechnology sensors are arranged in a configuration of array for multisensing and multiparameter devices. Wireless sensors at low-cost are integrated to implement a portable and mobile node, that can be used as early-detection system in a distributed sensor network. Real-time and continuous monitoring of hazardous air-contaminants (NO 2, CO, PAH, BTEX, etc.) has been performed in field measurements by comparison of chemical analyzers from environmental protection governmental agency (ARPA-Puglia). In addition, experimental campaigns of the integrated portable sensor-system have been realized for assessment of malodours emitted from an urban waste site. The results demonstrate that the sensor-system has a potential capacity for real-time measurements of air-pollutants, malodours from waste site, and control of landfill gas. © 2011 American Institute of Physics.
Author Keywords
Air quality control;  Electronic nose;  Gas sensors;  Malodours control;  Wireless sensors
Document Type: Conference Paper
Source: Scopus

 

Penza M.a, Suriano D.a, Cassano G.a, Rossi R.a, Alvisi M.a, Pfister V.a, Trizio, L.bc, Brattoli M.bc, De Gennaro G.bc
(2011) AIP Conference Proceedings, 1362, pp. 205-206.
a Brindisi Technical Unit of Technologies for Materials, ENEA-Italian National Agency for New Technologies, Energy and Sustainable Economic Development, SS 7 Appia Km 712, Brindisi, Italy
b Chemistry Department, University of Bari, via Orabona 4, Bari, Italy
c Lenviros Srl, Spin-off from University of Bari, via Orabona 4, Bari, Italy
Abstract
An array of commercial gas sensors and nanotechnology sensors has been integrated to quantify gas concentration of air-pollutants. A variety of chemoresistive gas sensors, commercial (Figaro and Fis) and developed at ENEA laboratories (metal-modified carbon nanotubes) were tested to implement a database useful for applied artificial neural networks (ANNs). The ANN algorithm used is the common perceptron multi-layer feed-forward network based on error back-propagation. Electronic Noses based on various sensor arrays related to mammalian olfactory systems have been largely reported [1,2]. Here, we reported on the perceptron-based ANNs applied to a large database of 3875 datapoints for environmental air monitoring. The ANNs performance has been individually assessed for any targeted gas. The response of the classifier has been measured for NO2, CO, CO2, SO2, and H2S gas. The NO2 characteristics exhibit that real concentrations and predicted concentrations are very close with a normalized mean square error (NMSE) in the test set as low as 6%. © 2011 American Institute of Physics.
Author Keywords
Carbon nanotubes; E-Nose; Environmental monitoring; Gas sensors; Neural networks
Document Type: Conference Paper
Source: Scopus

 

Di Benedetto F.ab , Camposeo A.a , Persano L.a , Laera A.M.c , Piscopiello E.c , Cingolani R.d , Tapfer L.c , Pisignano D.ab
(2011) Nanoscale, 3 (10), pp. 4234-4239.
a NNL, National Nanotechnology Laboratory, CNR-Istituto Nanoscienze, Università Del Salento, via Arnesano, I-73100 Lecce, Italy
b Dipartimento di Ingegneria dell'Innovazione, Università Del Salento, via Arnesano, I-73100, Lecce, Italy
c ENEA, Technical Unit for Material Technologies, Brindisi Research Centre, Strada Statale 7, I-72100 Brindisi, Italy
d Istituto Italiano di Tecnologia (I.I.T.), via Morego 30, I-16163 Genova, Italy
Abstract
We report on the simple, in situ generation of CdS nanocrystals inside electrospun polymer fibres by thermal decomposition of a cadmium thiolate precursor, leading to nanocomposite light-emitting fibres. The modifications induced in the precursor by the thermal decomposition are investigated by a morphological, structural and spectroscopic analysis of the resulting nanocomposite fibres. This approach allows us to overcome nanofabrication difficulties related to disfavoured micro- or nanofluidic molecular flow as given by the direct incorporation of particles in the electrospinning solution. This method therefore enables the synthesis of luminescent, CdS-based composite fibres with emission peaked in the visible range, suitable as building blocks for nanophotonic devices based on light-emitting nanomaterials. © 2011 The Royal Society of Chemistry.
Document Type: Article
Source: Scopus

 

Penza M.a, Rossi R.a, Alvisi M.a, Valerini D.a, Serra E.a, Martinelli E.b, Di Natale C.b, D'Amico A.b
(2011) Lecture Notes in Electrical Engineering, 91 LNEE, pp. 73-79.
a Brindisi Technical Unit for Technologies of Materials, ENEA, PO Box 51, Postal Office Br4, 72100 Brindisi, Italy
b Department of Electronic Engineering, University of Rome Tor Vergata, Via di Tor Vergata 110, 00133 Rome, Italy
Abstract
Thermoelectric power (TEP) of the carbon nanotubes (CNTs) films, grown by radiofrequency plasma-enhanced chemical vapor technology onto silicon substrates, has been measured. Two different metal contacts of Cr-Al and Cr-Au have been fabricated for the CNTs-based thermocouples and preliminarily investigated. The CNTs-based thermocouples exhibit large values of TEP due to the Schottky barriers at semiconducting CNTs-metal junctions. The highest TEP of 40.7 μV/K has been achieved for the thermocouple CNTs/Cr-Al. This value is enhanced of about 2 times compared to single-walled CNTs bundles reported in literature (Collins et al. Science 287:1801-1804, 2000), and comparable to isolated suspended single-walled carbon nanotubes with Pt-electrodes reported in literature (Yu et al. Nano Lett 5(9):1842-1846, 2005) as well. The CNTs-thermocouples exhibit linear relationship for the output voltage versus temperature in the range from 20 to 70°C by providing an interesting nanomaterial for energy applications and temperature and/or radiation microsensors. © 2011 Springer Science+Business Media B.V.
Document Type: Conference Paper
Source: Scopus

 

Penza M.a, Rossi R.a, Alvisi M.a, Valerini D.a, Cassano G.a, Serra E.a, Paolesse R.b, Martinelli E.c, Di Natale C.c, D'Amico A.c
(2011) JoLecture Notes in Electrical Engineering, 91 LNEE, pp. 105-111.
a ENEA, Brindisi Technical Unit for Technologies of Materials, PO Box 51, Postal Office Br4, 72100 Brindisi, Italy
b Department of Electronic Engineering, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
c Department of Electronic Engineering, University of Rome Tor Vergata, Via di Tor Vergata 110, 00133 Rome, Italy
Abstract
Networked carbon nanotubes (CNTs) films have been grown by chemical vapor deposition (CVD) technology onto miniaturized Co-coated alumina substrates for NO2 and NH3 gas sensing applications, at a sensor temperature of 150°C. The sidewalls of the CNTs films have been modified by spray-coating with two different metalloporphyrins (MPPs) consisting of a TetraPhenylPorphyrin coordinated by a central metal of zinc (Zn-TPP) and manganese (Mn-TPP) for enhanced sensitivity and tailored specificity. It was demonstrated that the gas sensitivity of the MPPs-modified CNTs-sensors significantly improved by a factor up to four-times through a catalytic effect of the MPPs. The gas sensing properties of CNTs-sensors, including MPPs-modified CNTs, are characterized by a change of the electrical conductivity in a model of charge transfer with a semiconducting p-type character. A response of the CNTs-sensor functionalized with 2 spray-layers of Mn-TPP has been measured as 0.43% to 0.5 ppm NO2, and as 0.09% to 10 ppm NH3, at 150°C. The MPPs-functionalized CNTs-sensors exhibit high sensitivity, fast response, reversibility, good repeatability, sub-ppm range detection limit. © 2011 Springer Science+Business Media B.V.
Document Type: Conference Paper
Source: Scopus

 

Penza M.a, Aversa P.a, Rossi R.a, Alvisi M.a, Cassano G.a, Suriano D.a, Serra E.b
(2011) Lecture Notes in Electrical Engineering, 91 LNEE, pp. 271-277.
a Brindisi Technical Unit for Technologies of Materials, ENEA, PO Box 51, Postal Office Br4, 72100 Brindisi, Italy
b Casaccia Technical Unit for Technologies of Materials, ENEA, Via Anguillarese 301, 00060, Rome, Italy
Abstract
A Quartz Crystal Microbalance (QCM) gas sensor coated with carbon nanotubes (CNTs) layered films as chemically interactive nanomaterial is described. A QCM resonator integrated on AT-cut quartz substrate has been functionally characterized as oscillator at the resonant frequency of 10 MHz. The CNTs have been grown by chemical vapor deposition (CVD) system onto alumina substrates, coated with 2.5 nm thick Fe catalyst, at a temperature of 750°C in H 2/C2H2 gaseous ambient as active materials for gas sensors. CNTs multilayers, with and without buffer layer of cadmium arachidate (CdA), have been prepared by the Langmuir-Blodgett (LB) technique to coat at the double-side the QCM sensors for organic vapor detection, at room temperature. It was demonstrated that the highest mass sensitivity has been achieved for CNTs multilayer onto CdA buffer material due to the greatest gas adsorbed mass. The sensing properties of the CNTs-sensors at enhanced mass sensitivity have been investigated for three different vapors of ethylacetate, acetone and m-xylene in the range of gas concentration from 10 to 800 ppm. The CNTs-based QCM-sensors exhibit high sensitivity (e.g., 5.55 Hz/ppm to m-xylene of the CNTs-multilayer) at room temperature, fast response, linearity, reversibility, repeatability, low drift of the baseline frequency, potential sub-ppm range detection limit. © 2011 Springer Science+Business Media B.V.
Document Type: Conference Paper
Source: Scopus

 

Masala S.a, Del Gobbo S.b, Borriello C.a, Bizzarro V.c, La Ferrara V.a, Re M.d, Pesce E.d, Minarini C.a, De Crescenzi M.b, Di Luccio T.a
(2011) Journal of Nanoparticle Research,13 (12), pp. 6537-6544.
a ENEA Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Piazzale E. Fermi, Portici, 80055, Italy
b Department of Physics, University of Rome Tor Vergata, Via Della Ricerca Scientifica 1, Rome, 00133, Italy
c IMAST Portici, Piazzale E. Fermi, Portici, 80055, Italy
d ENEA Italian National Agency for New Technologies, Energy and Sustainable Economic Development, SS7 Appia Km 713, Brindisi, 72100, Italy
Abstract
The integration of semiconductor nanoparticles (NPs) into a polymeric matrix has the potential to enhance the performance of polymer-based solar cells taking advantage of the physical properties of NPs and polymers. We synthesize a new class of CdS-NPs-based active layer employing a low-cost and low temperature route compatible with large-scale device manufacturing. Our approach is based on the controlled in situ thermal decomposition of a cadmium thiolate precursor in poly(3-hexylthiophene) (P3HT). The casted P3HT:precursor solid foils were heated up from 200 to 300 °C to allow the precursor decomposition and the CdS-NP formation within the polymer matrix. The CdS-NP growth was controlled by varying the annealing temperature. The polymer:precursor weight ratio was also varied to investigate the effects of increasing the NP volume fraction on the solar cell performances. The optical properties were studied by using UV-Vis absorption and photoluminescence (PL) spectroscopy at room temperature. To investigate the photocurrent response of P3HT:CdS nanocomposites, ITO/P3HT:CdS/Al solar cell devices were realized. We measured the external quantum efficiency (EQE) as a function of the wavelength. The photovoltaic response of the devices containing CdS-NPs showed a variation compared with the devices with P3HT only. By changing the annealing temperature the EQE is enhanced in the 400-600 nm spectral region. By increasing the NPs volume fraction remarkable changes in the EQE spectra were observed. The data are discussed also in relation to morphological features of the interfaces studied by Focused Ion Beam technique. © 2011 Springer Science+Business Media B.V.
Author Keywords
CdS nanoparticles; Energy conversion; Nanocomposites; P3HT; Polymer solar cells
Document Type: Article
Source: Scopus


Di Girolamo G.a, Marra F.b, Blasi C.a, Serra E.c, Valente T.b
(2011) Ceramics International, 37 (7), pp. 2711-2717.
a ENEA, UTTMATB, Brindisi Research Centre, 72100 Brindisi, Italy
b Department of Chemical and Materials Engineering, University of Rome la Sapienza, UdR INSTM Roma la Sapienza, 00184 Rome, Italy
c ENEA, UTTMAT, Casaccia Research Centre, 00123 Rome, Italy
Abstract
Nanostructured yttria stabilized zirconia (YSZ) coatings were deposited by Atmospheric Plasma Spraying (APS). X-ray diffraction (XRD) was used to investigate their phase composition, while scanning electron microscopy (SEM) was employed to examine their microstructure. The coatings showed a unique and complex microstructure composed of well-melted splats with columnar crystal structure, partially melted areas, which resembled the morphology of the powder feedstock, and equiaxed grains. Vickers microhardness of nanostructured zirconia coatings was similar to that of the conventional ones and strongly depended on the indentation load. Otherwise, a higher thermal shock resistance was found. This effect was addressed to the retention of nanostructured areas in coating microstructure and to the corresponding high porosity. © 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Author Keywords
C. Hardness; C. Thermal shock resistance; D. ZrO2; E. Thermal applications; Plasma spraying
Document Type: Article
Source: Scopus

 

di Girolamo, G.ab, Pagnotta L.a
(2011) Recent Patents on Materials Science, 4 (3), pp. 173-190.
a Department of Mechanical Engineering, University of Calabria, Ponte Pietro Bucci, Cubo 44C, Rende (CS), 87036, Italy
b ENEA, Brindisi Research Centre, S.S. 7 Appia, km 706, 72100 Brindisi, Italy
Abstract
Thermally sprayed coatings are very effective tools for high-temperature applications in energy and aerospace industries. They are applied on the surface of complex components as those of turbine engines in order to provide enhanced thermal and environmental protection against heat transfer, high-temperature oxidation, hot-corrosion, wear and erosion. Thereby, they are suitable to significantly increase the capability and the durability of these components as well as the efficiency of turbine engines, in accordance with the growing demand for higher performance and lower environmental impact. The recent developments about anti-oxidant coatings, thermal barrier coatings (TBCs), environmental barrier coatings (EBCs), abradable coatings and wear resistant coatings are summarized in this paper. The patents related to these applications are reviewed. © 2011 Bentham Science Publishers.
Author Keywords
Abradables; Anti-wear coatings; Environmental barrier coatings; Thermal barrier coatings; Thermal spraying; Turbine engines
Document Type: Review
Source: Scopus

 

Fratoddi I.a, Venditti I.a, Battocchio C.b, Polzonetti G.b, Bondino F.c, Malvestuto M.d, Piscopiello E.e, Tapfer L.e, Russo M.V. a
(2011) Journal of Physical Chemistry C, 115 (31), pp. 15198-15204.
a Department of Chemistry, Sapienza University of Rome, P.le A. Moro 5, 00185 Rome, Italy
b Department of Physics, Unità INSTM and CISDiC University Roma Tre, Via della Vasca Navale 85, 00146 Rome, Italy
c Laboratorio Nazionale TASC, INFM-CNR, Area Science Park, 34012 Basovizza Trieste, Italy
d Sincrotrone Trieste, Area Science Park, I-34012 Trieste, Italy
e ENEA, UTTMATB, Centro Ricerche Brindisi, Strada Statale 7 Appia km.703, 72100 Brindisi, Italy
Abstract
The synthesis and characterization of gold nanoparticles (AuNPs-1) stabilized by a novel bifunctional thiolate organometallic complex containing Pt(II) centers, that is, trans,trans-[(CH3COS)(PBu3) 2Pt-C≡C-C6H4-C6H 4-C≡C-Pt(PBu3)2(SCOCH3)] (complex 1), has been carried out. As a comparison, gold nanoparticles stabilized with an organic thiol, allylmercaptane, that is, AuNPs-2, and self-assembled monolayers (SAMs) of both thiols were also prepared and investigated. The AuNPs-1 show a direct link between Pt(II) and Au nanoparticles through a single S bridge and are candidates for the achievement of 2D or 3D networks. The size control of the Au nanoparticles was achieved by careful control of synthesis parameters, and the hybrids were characterized by means of high-resolution transmission electron microscopy (HR-TEM) and synchrotron radiation induced X-ray photoelectron spectroscopy (SR-XPS). SR-XPS measurements allowed the assessment of the anchoring of the organic or organometallic thiols onto gold substrates as well as onto gold nanoparticles. AuNPs-2 with diameters in the range from 1.6 to 3.9 nm were obtained. AuNPs-1 with an average diameter in the range of 4.5-3.6 nm were obtained, and linkage between the nanoparticles can be envisaged with the formation of dyads supported by SR-XPS measurements. In fact, S2p core-level data indicate that both sulfur atoms of the organometallic thiol chemically interact with gold grafting vicinal nanoparticles. © 2011 American Chemical Society.
Document Type: Article
Source: Scopus

 

De Maria A.a, Aurora A.b, Montone A.b, Tapfer L.c, Pesce E.c, Balboni R.d, Schwarz M.b, Borriello C.a
(2011) Journal of Nanoparticle Research, 13 (11), pp. 6049-6058.
a ENEA, UTTP, P.le Fermi n.1, Portici, 80055, Italy
b ENEA, UTTMAT, Via Anguillarese, 301, Rome, 00123, Italy
c ENEA UTTMATB, SS 7 Appia KM 706, Brindisi, 72100, Italy
d CNR, IMM, Via P. Gobetti, 101, Bologna, 40129, Italy
Abstract
Commercially available Sodium clay (Dellite HPS) and organo-clay (Dellite 72T) are modified via a silylation reaction. These silylated clays are characterized by IR, XRD, thermogravimetric analyses, and their equilibrium contact angles are measured. They are used to prepare nanocomposites at different loading percentage (1, 3, 5% wt) by in situ intercalative polymerization of Methyl methacrylate and morphology and thermal properties of nanocomposites are examined. SEM images of nanocomposites fractured surface show the absence of clays aggregates, confirming a good dispersion and distribution of montmorillonites in the polymer matrix. The effects of modified clays on the thermal properties of nanocomposites are analyzed by differential scanning calorimetry and thermogravimetric analyses showing an increase of glass and decomposition temperatures of all nanocomposites respect to homopolymer ones. The best results are obtained in the presence of silylated montmorillonites, clearly the organosilane improves the compatibility between polymer matrix and clay and as effect the properties of nanocomposites. © 2011 Springer Science+Business Media B.V.
Author Keywords
Clay-polymer matrix nanocomposites; MMT; Organosilane; PMMA; Silylation; Thermal stability
Document Type: Conference Paper
Source: Scopus

 

Corcione C.E.a, Cavallo A.a, Pesce E.b, Greco A.a, Maffezzoli A.a
(2011) Polymer Engineering and Science, 51 (7), pp. 1280-1285.
a Department of Innovation Engineering, University of Salento, Via per Arnesano, Lecce 73100, Italy
b ENEA - Italian National Agency for New Technologies, Energy and the Environment-Advanced Physical Technologies, New Materials Department, S.S. 7 - Km 714, Brindisi 72100, Italy
Abstract
The aim of this paper is a comparison of the effectiveness of different macrocharacterization techniques for the prediction of the degree of dispersion and intercalation of bidimensional nanofillers in an amorphous thermoplastic matrix. Organically modified montmorillonites (omMMT) were used as bidimensional nanofillers, whereas amorphous polyethylene-terephthalate copolymer (PETg) was used as matrix. Wide angle x-ray diffraction analysis showed no relevant difference between the samples processed at different temperatures, all characterized by a predominantly intercalated structure. On the other hand, transmission electron microscopy (TEM) analysis showed the presence of some degree of exfoliation, as well as the presence of lamellar stacks of different thickness. The aspect ratio of lamellar stacks was estimated by means of rheological, mechanical, and gas permeability analysis. All techniques provided values which are in quite good agreement with TEM analysis. Furthermore, all techniques were able to capture the increase in the lamellar stack aspect ratio with decreasing processing temperature. Copyright © 2009 Society of Plastics Engineers.
Document Type: Article
Source: Scopus

 

Martina, V.a, De Riccardis M.F.a, Carbone D.a, Rotolo P.a, Bozzini B.b, Mele C.b
(2011) Journal of Nanoparticle Research, pp. 6035-6047. Cited 1 time.
a ENEA Technical Unit of Materials Technology of Brindisi, SS.7 Appia Km 706, Brindisi, 72100, Italy
b Dipartimento di Ingegneria dell'Innovazione, Università del Salento, Via Monteroni, Lecce, 73100, Italy
Abstract
Composite films of polyaniline (PANI) and carbon nanotubes (CNTs) were prepared by electrochemical co-deposition from solutions of the corresponding monomer containing two different kinds of CNTs. The first type was commercial (diameter = 110-170 nm, length = 5-9 μm) and the second one was home-made (diameter = 30 nm, length = 5-20 μm). The electrochemical behaviour of PANI-CNTs composite films was investigated with Cyclic Voltammetry and the surface morphology was analysed by Scanning Electron Microscopy (SEM). Subtractively Normalised Interfacial FT-IR procedure was used to investigate the presence of corrosion products when the films were deposited on stainless steel substrates and exposed to acid environment. The spectral investigations were utilised to understand the role of composite films in the corrosion protection and to discriminate the best performance CNTs. © 2011 Springer Science+Business Media B.V.
Author Keywords
Carbon nanotubes; Electrochemistry; FT-IR; Polyaniline
Document Type: Conference Paper
Source: Scopus

 

Penza M., Rossi, R., Alvisi M., Suriano D., Serra E.
(2011) Thin Solid Films, 520 (3), pp. 959-965.
ENEA, Brindisi Technical Unit of Technologies for Materials, PO Box 51-Br4, I-72100 Brindisi, Italy
Abstract
Carbon nanotubes (CNTs) networked films have been grown by chemical vapor deposition (CVD) technology onto miniaturized low-cost alumina substrates, coated by nanosized Co-catalyst for growing CNTs, to perform chemical detection of toxic gasses (NO2 and NH3), greenhouse gasses (CO2 and CH4) and domestic safety gasses (CO and C2H5OH) at an operating sensor temperature of 120 °C. The morphology and structure of the CNTs networks have been characterized by scanning electron microscopy (SEM). A dense network of bundles of multiple tubes consisting of multi-walled carbon nanostructures appears with a maximum length of 1-5 μm and single-tube diameter varying in the range of 5-40 nm. Surface modifications of the CNTs networks with sputtered Platinum (Pt) nanoclusters, at tuned loading of 8, 15 and 30 nm, provide higher sensitivity for significantly enhanced gas detection compared to un-decorated CNTs. This could be caused by a spillover of the targeted gas molecules onto Pt-catalyst surface with a chemical gating into CNTs layers. The measured electrical conductance of the functionalized CNTs upon exposures of a given oxidizing and reducing gas is modulated by a charge transfer model with p-type semiconducting characteristics. The effect of activated carbons as chemical filters to reduce the influence of the domestic interfering alcohols on CO gas detection has been studied. Functionalized CNT gas sensors exhibited better performances compared to unmodified CNTs, making them highly promising candidates for functional applications of gas control and alarms. © 2011 Elsevier B.V. All rights reserved.
Author Keywords
Carbon nanotubes networks; Gas sensors; Platinum-decoration
Document Type: Conference Paper
Source: Scopus

 

Calò E.ab, Greco A.a, Maffezzoli A.a
(2011) Polymer Degradation and Stability, 96 (5), pp. 784-789.
a Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce, Italy
b ENEA - Italian National Agency for New Technologies, Energy and the Environment-Advanced Physical Technologies and New Materials Dept., S.S. 7 - Km 714, 72100 Brindisi, Italy
Abstract
Soft PVC was obtained by using a new plasticizer, based on cardanol, a renewable resource characterized by chemical and physical properties very close to those of diethylhexyl phthalate (DEHP). Cardanol acetate (CA) was obtained by solvent free esterification of cardanol, and used as secondary plasticizer, by partial substitution of DEHP in soft PVC formulations. Ageing tests were performed in order to study the stability of properties of the soft PVC formulations related to plasticizer diffusion. Tensile properties and hardness changes were used to monitor the macroscopic effects of plasticizer diffusion. Soft PVC obtained by partial substitution of DEHP by CA showed a significant modification of mechanical properties related to a higher plasticizer evaporation during ageing tests. Migration tests confirmed that CA is characterized by a higher diffusivity in soft PVC compared to DEHP. © 2011 Published by Elsevier Ltd.
Author Keywords
Cardanol; Diffusion; Plasticizer; PVC; Renewable resource
Document Type: Article
Source: Scopus

 

Brattoli M.a, de Gennaro G.a, de Pinto V.a, Loiotile A.D.a, Lovascio S.a, Penza M.b
(2011) Sensors, 11 (5), pp. 5290-5322.
a Department of Chemistry, University of Bari, via E.Orabona 4, 70126 Bari, Italy
b Brindisi Technical Unit for Technologies of Materials, ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, P.O. Box 51 Br-4, I-72100 Brindisi, Italy
Abstract
The complexity of the odours issue arises from the sensory nature of smell. From the evolutionary point of view olfaction is one of the oldest senses, allowing for seeking food, recognizing danger or communication: human olfaction is a protective sense as it allows the detection of potential illnesses or infections by taking into account the odour pleasantness/unpleasantness. Odours are mixtures of light and small molecules that, coming in contact with various human sensory systems, also at very low concentrations in the inhaled air, are able to stimulate an anatomical response: the experienced perception is the odour. Odour assessment is a key point in some industrial production processes (i.e., food, beverages, etc.) and it is acquiring steady importance in unusual technological fields (i.e., indoor air quality); this issue mainly concerns the environmental impact of various industrial activities (i.e., tanneries, refineries, slaughterhouses, distilleries, civil and industrial wastewater treatment plants, landfills and composting plants) as sources of olfactory nuisances, the top air pollution complaint. Although the human olfactory system is still regarded as the most important and effective "analytical instrument" for odour evaluation, the demand for more objective analytical methods, along with the discovery of materials with chemo-electronic properties, has boosted the development of sensor-based machine olfaction potentially imitating the biological system. This review examines the state of the art of both human and instrumental sensing currently used for the detection of odours. The olfactometric techniques employing a panel of trained experts are discussed and the strong and weak points of odour assessment through human detection are highlighted. The main features and the working principles of modern electronic noses (E-Noses) are then described, focusing on their better performances for environmental analysis. Odour emission monitoring carried out through both the techniques is finally reviewed in order to show the complementary responses of human and instrumental sensing. © 2011 by the authors; licensee MDPI, Basel, Switzerland.
Author Keywords
Dynamic olfactometry; Electronic nose; GC-O; Odour concentration; Odour detection; Sampling methods; Sensors; Sensory methods
Document Type: Review
Source: Scopus

 

Resta V.ab, Gonzalo J.a, Afonso C.N.a, Piscopiello E.b, Garca López J.c
(2011) Journal of Applied Physics, 109 (9), art. no. 094302. Cited 1 time.
a Laser Processing Group, Instituto de Óptica, CSIC, Serrano 121, E-28006 Madrid, Spain
b ENEA, Unità Tecnica Tecnologie Dei Materiali Brindisi (UTTMATB), Strada Statale 7 Appia-Km 706, I-72100 Brindisi, Italy
c Centro Nacional de Aceleradores, Universidad de Sevilla/CSIC, T.A. Edison, Isla de la Cartuja E-41092, Spain
Abstract
The effects induced during the covering/embedding of metal nanoparticles (NPs) produced by pulsed laser deposition (PLD) and their impact on the structural and optical properties have been studied by producing pairs of samples containing Au NPs that are either uncovered (i.e., at the surface) or covered (i.e., embedded in an amorphous a-Al2O3 host). The main result is that covering species can sputter up to 100% of the Au atoms, the smaller the NPs the higher the sputtered fraction. This fraction has been simulated using standard models for ion bombardment and taking into account the kinetic energy distribution of arriving species and the cohesive energy dependence on NPs dimensions. Although all models well predict the order of magnitude of the sputtering yield, the calculated values are generally smaller than the experimental ones and do not account for the experimental dependence on NPs dimensions. This disagreement is discussed in terms of the limitations of standard models that do not take into account the lower adhesion of small NPs to the substrate, the high flux of species involved in PLD and, possibly to lesser extent, the use of some bulk material parameters. The metal sputtering during the coverage regulates the NPs morphology, through a reduction of dimensions and dimension dispersion. Most changes of structural features and optical spectra when covering the NPs are directly related to the variation in the amount of metal with the exception of a strong blueshift of the surface plasmon resonance when NPs are covered. This shift could be consistent with mixing of covering layer species and metal at the surface of the NPs. © 2011 American Institute of Physics.
Document Type: Article
Source: Scopus

 

Lisi N.a, Giorgi R.a, Re M.b, Dikonimos T.a, Giorgi L.a, Salernitano E.a, Gagliardi S.a, Tatti F.c
(2011) Carbon, 49 (6), pp. 2134-2140. Cited 1 time.
a ENEA, Casaccia Research Centre, Via Anguillarese 301, 00123 S. Maria di Galeria, Roma, Italy
b ENEA, Brindisi Research Centre, Strada Statale 7 Appia, km 706, 72100 Brindisi (BR), Italy
c FEI Company, Achtseweg-noord 5, 5651 GG Eindhoven, Netherlands
Abstract
Carbon nanowall films were synthesized by plasma enhanced hot filament chemical vapour deposition on carbon paper, a three dimensionally structured material. The micro-structured nature of the carbon paper, which is composed of an irregular and open mesh of carbon fibres, allowed one to determine the microstructure of the carbon nanowalls both at the tip and at the fibre-nanowall base interface. The number of graphenes which pile up to form the structure of a single nanowall ranges from 1 to 2 at the tip up to several 10s at the base, making this material suitable to study and eventually exploit the electronic properties of graphenes on a macroscopic scale. Such material is promising for electrochemical applications. © 2011 Elsevier Ltd. All rights reserved.
Document Type: Article
Source: Scopus

 

Giorgi R.a, Giorgi L.a, Gagliardi S.a, Salernitano E.a, Alvisi M.b, Dikonimos Th.a, Lisi N.a, Valerini D.b, De Riccardis M.F.b, Serra E.a
(2011) Journal of Fuel Cell Science and Technology, 8 (4), art. no. 041004.
a ENEA Centro Ricerche Casaccia, Via Anguillarese 301, 00123 Rome, Italy
b ENEA Centro Ricerche Brindisi, S. S. Appia, Km 7+300, 72100 Brindisi, Italy
Abstract
The real market penetration of polymer electrolyte fuel cells is hindered by the high cost of this technology mainly due to the expensive platinum catalyst. Two approaches are followed to reduce the cost: one way is to increase the Pt utilization efficiency reducing at the same time the total load and the other way is to increase the catalytic activity of the catalyst/support assembly. In this work, the increase of utilization efficiency is addressed by optimizing the catalyst distribution on the uppermost layer of the electrode via electrodeposition and sputter deposition, while the improvement of the catalyst activity is pursued by nanostructuring the catalysts and the carbon-based supports. A very low Pt loading (0.006 mg cm-2) was obtained by sputter deposition on electrodes that exhibited a mass specific activity for methanol oxidation reaction better than a commercial product. Carbon nanofibers used as catalyst support of electrodeposited platinum nanoparticles resulted in improved mass specific activity and long term stability compared to conventional carbon-based supports. Finally, PtAu alloys developed by sputter deposition were found more efficient than commercial PtRu catalyst for the methanol oxidation reaction. In conclusion, polymer electrolyte membrane fuel cell electrode based on nanomaterials, developed by combining physical and chemical deposition processes, showed outstanding electrochemical performance. © 2011 American Society of Mechanical Engineers.
Author Keywords
carbon nanofibers; chemical vapor deposition; electrodeposition; PEM; sputter deposition
Document Type: Article
Source: Scopus

 

Penza M.a, Sadek, A.Z.b, Zheng, H.D.c, Aversa, P.a, McCulloch, D.G.b, Kalantar-Zadeh, K.c, Wlodarski, W.c
(2011) Sensor Letters, 9 (2), pp. 925-928.
a ENEA, Brindisi Technical Unit of Technologies for Materials, PO Box 51, 72100 Brindisi, Italy
b School of Applied Sciences, Applied Physics, RMIT University, Melbourne, VIC 3001, Australia
c School of Electrical Computer Engineering, RMIT University, Melbourne, VIC 3001, Australia
Abstract
A surface acoustic wave (SAW) sensor with titania nanotubular layer as the gas sensitive material has been developed. This SAW 433 MHz two-port resonator has been fabricated on ST-cut quartz substrate and functionally characterized as an oscillator in dual differential mode. Solvent-casting coatings of anodized TiO2 nanotubes have been used for coating the devices for room-temperature detection of Volatile Organic Compounds (VOCs) including methanol, ethanol, acetone and m-xylene as well as hydrogen gas. The results demonstrate linear responses and high sensitivity of these sensors with the largest sensitivity achieved for ethanol to be 156 kHz/ppm at room temperature. Copyright © 2011 American Scientific Publishers All rights reserved.
Author Keywords
SAW gas sensors; Sensor nanomaterials; Titania nanotubes films
Document Type: Conference Paper
Source: Scopus

 

Penza M.a, Sadek A.Z.b, Aversa P.a, McCulloch D.G.b, Wlodarski W.c, Kalantar-Zadeh, K.c
(2011) Sensor Letters, 9 (2), pp. 920-924.
a ENEA, Brindisi Technical Unit of Technologies for Materials, PO Box 51, 72100 Brindisi, Italy
b School of Applied Sciences, Applied Physics, RMIT University, Melbourne, VIC 3001, Australia
c School of Electrical Computer Engineering, RMIT University, Melbourne, VIC 3001, Australia
Abstract
A surface acoustic wave (SAW) gas sensor incorporating metal oxides nanoplatelets layers as chemically interactive material is presented. SAW two-port resonators fabricated using a ST-cut quartz substrate were used as an oscillators in dual differential mode operating at the resonant frequency of 433.92 MHz. Anodized W03 and evaporated MoO3 nanoplatelets were drop casted onto the SAW microdevices for room-temperature detection of Volatile Organic Compounds (VOCs) such as methanol, ethanol, acetone and m-xylene. Response of the device to hydrogen was also investigated. While operating at room temperature, for MoO3 nanoplatelets layers the highest sensitivity of 14 Hz/ppm was obtained for methanol sensing, and the highest ethanol sensitivity of 79.6 Hz/ppm measured using WO3 nanoplatelets. Copyright © 2011 American Scientific Publishers All rights reserved.
Author Keywords
Metal oxides nanoplatelets films; SAW gas sensors; Sensor nanomaterials
Document Type: Conference Paper
Source: Scopus

 

Penza M.a, Rossi R.a, Alvisi M.a, Valermi D.a, Serra E.a, Paolesse R.b, Martinelli E.c, D'Amico A.c, Di Natale C.c
(2011) Sensor Letters, 9 (2), pp. 913-919.
a ENEA, Brindisi Technical Unit of Technologies for Materials, PO Box 51, I-72100 Brindisi, Italy
b University of Rome, Tor Vergata, Department of Chemical Sciences and Technologies, Rome, Italy
c University of Rome, Tor Vergata, Department of Electronic Engineering, Rome, Italy
Abstract
Networked films of carbon nanotubes (CNTs) have been grown by CVD technology onto low-cost miniaturized alumina substrates. The sidewalls of the CNTs films have been modified by spray-coating with two different metalloporphyrins (MPPs) consisting of a TetraPhenylPorphyrin coordi-nated by a central metal of zinc (Zn-TPP) and manganese (Mn-TPP) for enhanced sensitivity and tailored specificity. Hazardous gases such as NO2, NH 3, H2S, SO2, and CO have been detected with various responsiveness in the range of concentration from 0.1 to 1000 ppm. The response of the chemiresistors in terms of p-type electrical conductance has been investigated as a function of the thickness of the functionalizing MPPs; and the effect of the temperature ranging from 20 to 150 °C on the sensor response has been addressed as well. A response of the CNT-sensor functionalized by 2 layers of Mn-TPP has been measured as 0.025% towards 0.5 ppm NO 2, at 150 °C. Copyright © 2011 American Scientific Publishers All rights reserved.
Author Keywords
Carbon nanotubes networked films;  Gas sensors;  Metalloporphyrins
Document Type: Conference Paper
Source: Scopus

 

Kalantar-Zadeh K.a, Spetz A.L.b, Penza M.c, Bhaskaran M.a, Sriram S.a, Wlodarski W.a, Faraone L.d, Matthews G.a
(2011) Sensor Letters, 9 (2), pp. 584-586.
a School of Electrical and Computer Engineering, RMIT University, Melbourne, VIC 3001, Australia
b Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linkoping, Sweden
c ENEA, Department of Physical Technologies and New Materials, I-72 100 Brindisi, Italy
d School of Electrical Electronic and Computer Engineering, University of Western Australia, Crawley, WA 6009, Australia
Document Type: Editorial
Source: Scopus

 

Penza M.a, Alvisi M.a, Rossi R.a, Serra E.a, Paolesse R.bcd, D'Amico A.cd, Di Natale C.cd
(2011) Nanotechnology, 22 (12), art. no. 125502.
a ENEA, Brindisi Technical Unit for Technologies of Materials, PO Box 51 Br-4, I-72100 Brindisi, Italy
b Department of Chemical Science and Technology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Roma, Italy
c Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Roma, Italy
d CNR-IDASC, Via del Fosso del Cavaliere, 00133 Roma, Italy
Abstract
Porphyrins have been widely used for many years as functional materials for chemical sensors. Their outstanding chemical features are balanced by some restrictions in terms of transduction techniques. In particular, porphyrin layers are barely conductive, with the consequence that the fabrication of porphyrin based chemiresistors is not possible, except in few rare cases. On the other hand, carbon nanotubes (CNTs) have superior electric properties ranging from metallic to semiconductor in character. Although the conductivity of CNTs is very sensitive to adsorbed molecules, it should be considered that the adsorption onto carbon structures is also scarcely selective and cannot be modified unless other molecular recognition systems are coupled with the CNTs. Following this approach, in this paper we investigated the sensing properties of hybrid CNT-porphyrin films to explore the possibility of transducing the adsorption events occurring in a porphyrin layer into resistance changes of the CNT layers. The results obtained indicate that the presence of the porphyrin films increases the sensitivity of the electric resistance of the CNTs to the concentration of volatile compounds. This enhancement is probably due to the catalytic effect of the metalloporphyrin in conveying the charge transfer from the adsorbate molecule to the CNTs substrate. This property of metalloporphyrins may introduce a further differentiation between porphyrin based sensors that could be positively utilized in sensor array configurations. © 2011 IOP Publishing Ltd Printed in the UK & the USA.
Document Type: Article
Source: Scopus

 

Caricato A.P.a, Cretí A.b, Luches A.a, Lomascolo M.b, Martino M.a, Rella R.b, Valerini D.ac
(2011) Laser Physics, 21 (3), pp. 588-597.
a Dipartimento di Fisica, Università Del Salento, Lecce 73100, Italy
b Istituto per la Microelettronica Ed i Microsistemi, IMM-CNR, Lecce, Italy
c ENEA, C.R. Brindisi, Brindisi 72100, Italy
Abstract
Various kinds of zinc oxide (ZnO) nanostructures, such as columns, pencils, hexagonal pyramids, hexagonal hierarchical structures, as well as smooth and rough films, were grown by pulsed laser deposition using KrF and ArF excimer lasers, without use of any catalyst. ZnO films were deposited at substrate temperatures from 500 to 700°C and oxygen background pressures of 1, 5, 50, and 100 Pa. Quite different morphologies of the deposited films were observed using scanning electron microscopy when different laser wavelengths (248 or 193 nm) were used to ablate the bulk ZnO target. Photoluminescence studies were performed at different temperatures (down to 7 K). The gas sensing properties of the different nanostructures were tested against low concentrations of NO 2. The variation in the photoluminescence emission of the films when exposed to NO2 was used as transduction mechanism to reveal the presence of the gas. The nanostructured films with higher surface-to-volume ratio and higher total surface available for gas adsorption presented higher responses, detecting NO2 concentrations down to 3 ppm at room temperature. © 2011 Pleiades Publishing, Ltd.
Document Type: Article
Source: Scopus

 

De Riccardis M.F.a, Martina V.a, Carbone D.a, Re M.a, Pesce E.a, Terzi R.a, Bozzini B.b
(2011) Materials Chemistry and Physics, 125 (1-2), pp. 271-276.
a ENEA, Department of Advanced Physical Technologies and New Materials, Brindisi Research Centre, SS 7 Appia, Km 706, Brindisi 72100, Italy
b Università Del Salento, Dipartimento di Ingegneria dell'Innovazione, via Monteroni, Lecce 73100, Italy
Abstract
An electrophoretic deposition (EPD) process was successfully used to obtain a composite epoxy coating containing montmorillonite. To disperse and obtain the intercalation of montmorillonite particles, a suitable procedure was optimized. This procedure did not require the use of additional chemicals and it was performed at room temperature. The microstructural analysis (TEM and XRD) confirmed that the intercalation of montmorillonite layers with epoxy was achieved. Functional characterisations (EIS and TMA) demonstrated the improved properties of the reinforced epoxy coating with respect to the simple epoxy coating. Moreover, the EPD process resulted more efficient in obtaining a montmorillonite-reinforced epoxy coating than a simple epoxy coating. © 2010 Elsevier B.V. All rights reserved.
Author Keywords
Coatings;  Composite materials;  Corrosion;  Thermal properties
Document Type: Article
Source: Scopus

 

Vitale F.a, Fratoddi I.b, Battocchio C.c, Piscopiello E.a, Tapfer L.a, Russo M.V.b, Polzonetti G.c, Giannini C.d
(2011) Nanoscale Research Letters, 6 (1), pp. 1-9.
a ENEA (Italian National Agency for New Technologies, Energy and the Sustainable Economic Development), UTTMATB (Technical Unit of Materials Technologies - Brindisi), Brindisi Research Centre, S.S. 7 Appia km. 706, 72100 Brindisi, Italy
b Dept. of Chemistry, University of Rome La Sapienza, P.le A. Moro n. 5, 00185 Roma, Italy
c Dept. of Physics, INFM, INSTM and CISDiC Unit, University Roma Tre, Via della Vasca Navale n. 84, 00146 Roma, Italy
d Istituto di Cristallografia (IC), CNR, via Amendola 122/O, 70126 Bari, Italy
Abstract
Stable gold nanoparticles stabilized by different mono and bi-functional arenethiols, namely, benzylthiol and 1,4- benzenedimethanethiol, have been prepared by using a modified Brust's two-phase synthesis. The size, shape, and crystalline structure of the gold nanoparticles have been determined by high-resolution electron microscopy and full-pattern X-ray powder diffraction analyses. Nanocrystals diameters have been tuned in the range 2 ÷ 9 nm by a proper variation of Au/S molar ratio. The chemical composition of gold nanoparticles and their interaction with thiols have been investigated by X-ray photoelectron spectroscopy. In particular, the formation of networks has been observed with interconnected gold nanoparticles containing 1,4-benzenedimethanethiol as ligand. © 2011 Vitale et al.
Document Type: Article
Source: Scopus

 

Laera A.M., Resta V. , Ferrara M.C., Schioppa M., Piscopiello E., Tapfer L.
(2011) Journal of Nanoparticle Research, 13 (11) , pp. 5705-5717.
ENEA, UTTMATB, Centro Ricerche Brindisi, Strada Statale Appia km. 706, 72100 Brindisi, Italy
Abstract
Efficient solar energy conversion is strongly related to the development of new materials with enhanced functional properties. In this context, a wide variety of inorganic, organic, or hybrid nanostructured materials have been investigated. In particular, in hybrid organic-inorganic nanocomposites are combined the convenient properties of organic polymers, such as easy manipulation and mechanical flexibility, and the unique size-dependent properties of nanocrystals (NCs). However, applications of hybrid nanocomposites in photovoltaic devices require a homogeneous and highly dense dispersion of NCs in polymer in order to guarantee not only an efficient charge separation, but also an efficient transport of the carriers to the electrodes without recombination. In previous works, we demonstrated that cadmium thiolate complexes are suitable precursors for the in situ synthesis of nanocrystalline CdS. Here, we show that the soluble [Cd(SBz) 2] 2(1- methyl imidazole) complex can be efficiently annealed in a conjugated polymer obtaining a nanocomposite with a regular and compact network of NCs. The proposed synthetic strategies require annealing temperatures well below 200 °C and short time for the thermal treatment, i.e., less than 30 min. We also show that the same complex can be used to synthesize CdS NCs in mesoporous TiO 2. The adsorption of cadmium thiolate molecule in TiO 2 matrix can be obtained by using chemical bath deposition technique and subsequent thermal annealing. The use of NCs, quantum dots, as sensitizers of TiO 2 matrices represents a very promising alternative to common dye-sensitized solar cells and an interesting solution for heterogeneous photocatalysis. © Springer Science+Business Media B.V. 2010.
Author Keywords
Conjugated polymers; Hybrid organic-inorganic; In situ synthesis; Nanocomposites; Photovoltaics; Semiconductor nanocrystals; Sustainable development; Unimolecul
Document Type: Conference Paper
Source: Scopus

 

Ferrara M.C.a , Piscopiello E.a, Laera A.M.a, Pilloni L.b, Mazzarelli S.a, Tapfer L.a
(2011) Journal of Sol-Gel Science and Technology, 60 (3), pp. 333-339.
a Technical Unit for Materials Technologies, Brindisi Research Centre, Strada Statale 7 Appia, 72100 Brindisi, Italy
b ENEA, Technical Unit for Materials Technologies, Casaccia Research Centre, Via Anguillarese, 301, 00123 S Maria di Galeria, Rome, Italy
Abstract
Polycrystalline, close-packed, homogeneous nanostructured ceria thin films were prepared by sol-gel process via dip-coating technique on soda-lime glass and (100)-oriented Si substrates. To produce the films, a sol was prepared using, as precursor, a home made cerium secbutoxide dissolved in secondary butanol. The chemical composition, the microstructural/morphological characteristics and the optical properties of the coatings were investigated in detail. The experimental results clearly demonstrate that the ceria films are nanocrystalline (CeO 2, cubic phase Fm̄3m) with an average grain size of about 2-3 nm for the samples grown on glass and of about 4-5 nm for the samples grown on silicon. The analyses of ceria layers grown on silicon show that the ceria coatings are free from organic residues and that a Si-oxide layer is formed at the film/substrate interface. The optical results evidence a red shift of the energy gap of about 0.5 eV that can be ascribed to conversion of relevant Ce 4+ sites to Ce 3+ sites and a consequent creation of oxygen vacancy at the surface of the ceria grains. © 2011 Springer Science+Business Media, LLC.
Author Keywords
Ceria; Ceria-alkoxide; Complex refractive index; Energy gap; Nanostructured thin films
Document Type: Article
Source: Scopus

 

Laera A.M., Resta V., Piscopiello E., Schioppa M., Tapfer L .
(2011) Materials Research Society Symposium Proceedings, 1322, pp. 45-50.
ENEA, Unità Tecnica Tecnologia dei Materiali Brindisi (UTTMATB), S.S. 7 Appia km 706, 72100 Brindisi, Italy
Abstract
Inorganic-organic nanocomposites, with II-VI or III-V semiconductor nanocrystals (NCs) embedded in semiconducting polymer matrix, are very promising materials for photovoltaic applications. Here, we present an effective and easy synthesis procedure to obtain a hybrid nanocomposite with CdS NCs dispersed in poly[2-methoxy-5-(2-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) conjugated polymer. CdS NCs are synthesized directly within the matrix through the decomposition of a suitable unimolecular precursor dispersed homogeneously in the polymer. We show that CdS NCs are formed at low annealing temperature avoiding structural damages and without affecting the functional properties of the MEH-PPV polymer. The NCs diameter ranges between 1.5nm and 4nm depending on the annealing temperature. In addition, no coalescence phenomena of CdS NCs were noticed in TEM observations even at very high particle density (40 wt %). Copyright © 2011 Materials Research Society.
Author Keywords
Annealing temperatures; CdS; Functional properties; Hybrid nanocomposites; II-IV semiconductors; Inorganic-organic nanocomposites; matrix; MEH-PPV; Particle densities; Photovoltaic applications; Structural damages; Synthesis procedure; TEM observations; Unimolecular
Document Type: Conference Paper
Source: Scopus