Eugenio Tondello

Electron transport through single Mn12 molecular magnets

We report transport measurements through a single-molecule magnet, the Mn12 derivative [Mn12O12(O2C-C6H4-SAc)16(H2O)4], in a single-molecule transistor geometry. Thiol groups connect the molecule to gold electrodes that are fabricated by electromigration. Striking observations are regions of complete current suppression and excitations of negative differential conductance on the energy scale of the anisotropy barrier of the molecule. Transport calculations, taking into account the high-spin ground state and magnetic excitations of the molecule, reveal a blocking mechanism of the current involving nondegenerate spin multiplets.

Electron Transport through SingleMn12Molecular Magnets

We report transport measurements through a single-molecule magnet, the Mn12 derivative [Mn12O12(O2C-C6H4-SAc)16(H2O)4], in a single-molecule transistor geometry. Thiol groups connect the molecule to gold electrodes that are fabricated by electromigration. Striking observations are regions of complete current suppression and excitations of negative differential conductance on the energy scale of the anisotropy barrier of the molecule. Transport calculations, taking into account the high-spin ground state and magnetic excitations of the molecule, reveal a blocking mechanism of the current involving nondegenerate spin multiplets.

The Potential of Supported Cu2O and CuO Nanosystems in Photocatalytic H2 Production

Hy wire: Supported Cu(2)O nanosystems and CuO nanowires obtained by chemical vapor deposition were used in the photocatalytic splitting of methanol/water solutions to produce hydrogen. The results obtained with these systems open appealing perspectives for the clean conversion of sunlight into storable chemical energy.

Photocatalytic and antibacterial activity of TiO2 and Au/TiO2 nanosystems

This work focuses on the photocatalytic performances and antibacterial activity of TiO2 and Au/TiO2 nanosystems. While the former are obtained by a sol?gel route, the latter are synthesized by an innovative hybrid RF-sputtering/sol?gel approach, followed by ex situ annealing in air up to 600??C. Important information on nanoparticle size, shape and distribution is obtained by the combined use of glancing incidence x-ray diffraction (GIXRD) and field emission-scanning electron microscopy (FE-SEM). Subsequently, the photocatalytic performances of the obtained nanosystems in the decomposition of the azo-dye Plasmocorinth B and their antibacterial activity in the elimination of Bacillus subtilis are illustrated and discussed in comparison with films obtained from standard Degussa P25 powders. The obtained results show a significant dependence of the functional performances on the systems compositional, structural and morphological properties. In particular, the dispersion of gold nanoparticles on the TiO2 matrix has a beneficial influence on the azo-dye photodegradation, whereas the antimicrobial activity of Au/TiO2 films is retarded with respect to pure TiO2.

A sol–gel approach to nanophasic copper oxide thin films

Abstract Nanostructured copper oxide films were prepared via sol–gel starting from ethanolic solutions of copper (II) acetate [Cu(CH 3 COO) 2 ·H 2 O]. Films were obtained by dip-coating at room temperature in air and were subsequently heat-treated at different temperatures (100–900 °C) in oxidizing (air), inert (N 2 ) or reducing (4% H 2 in N 2 ) atmospheres. The evolution of the oxide coatings under thermal treatment was studied by glancing incidence X-ray diffraction, X-ray photoelectron spectroscopy and X-ray excited Auger electron spectroscopy. Different crystalline phases were observed as a function of the annealing conditions. Depending on both temperature and atmosphere, the film composition resulted single- or multi-phasic. All the layers were nanostructured with an average crystallite size lower than 20 nm. The most relevant results concerning sample composition and microstructure as well as their mutual relations with the synthesis conditions are presented and discussed.

F-Doped Co3O4 Photocatalysts for Sustainable H2 Generation from Water/Ethanol

p-Type Co(3)O(4) nanostructured films are synthesized by a plasma-assisted process and tested in the photocatalytic production of H(2) from water/ethanol solutions under both near-UV and solar irradiation. It is demonstrated that the introduction of fluorine into p-type Co(3)O(4) results in a remarkable performance improvement with respect to the corresponding undoped oxide, highlighting F-doped Co(3)O(4) films as highly promising systems for hydrogen generation. Notably, the obtained yields were among the best ever reported for similar semiconductor-based photocatalytic processes.

Semi-empirical molecular orbital theory. The one-centre quantities for the elements of the first and second transition series

Abstract One-centre quantities for the elements of the first and second transition metal series are given which can be used instead of the corresponding one-centre integrals in semi-empirical MO calculations.

Poly[(oligoethylene glycol) dihydroxytitanate] as organic-inorganic polymer-electrolytes

Abstract Two new poly[(oligoethylene glycol) dihydroxytitanate] electrolytic systems were prepared by a polycondensation reaction between: Ti(OEt) 4 and polyethylene glycol 400 (PEG 400) (I), and Ti(OEt) 4 and PEG 400/LiCl complex (II). The polymers thus obtained show a solid rubbery consistency and are very stable under inert atmosphere. The structure, morphology and conductivity of these materials were investigated. On the basis of analytical data and vibrational studies it was concluded that polymers (I) and (II) are inorganic–organic materials with titanium atoms bonded together by PEG bridges. Particularly, inter-chain interactions in polymer (I) occur by means of hydrogen bonds between titanium hydroxyl groups and ethereal oxygens of PEG chains, while polymer (II) contains both titanium–PEG interactions and a second type of inter-chain interaction due to the presence of hydrogen bonding clusters around Cl − ions. Scanning electron microscopy (SEM) revealed two types of morphologies in polymers (I) and (II). Conductivity measurements made at different temperatures indicated that both polymers conduct ionically. Two conductivity mechanisms are present in these materials, which are strongly influenced by segmental motions of the polymer chains. At 25°C polymers (I) and (II) showed conductivities of ca. 3×10 −6 and 4×10 −6 S cm −1 , respectively.

Columnar CeO2 nanostructures for sensor application

CeO2 columnar nanostructures with tailored properties were synthesized by chemical vapour deposition on Si(100) and Al2O3 substrates between 350 and 450 °C and characterized in their structure, composition and morphology by means of a multi-technique approach. Their higher sensitivity in the detection of gaseous ethanol and nitrogen dioxide with respect to continuous CeO2 thin films opens interesting perspectives for the development of nanosized sensor devices.

Controlled vapor-phase synthesis of cobalt oxide nanomaterials with tuned composition and spatial organization

Cobalt oxide nanostructures are deposited by Chemical Vapor Deposition (CVD) on Si(100) substrates at temperatures between 300 and 550 °C, using for the first time a novel Co(II) adduct as molecular precursor [Co(hfa)2·TMEDA; hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate, TMEDA = N,N,N′,N′-tetramethylethylenediamine]. The preparation is conducted either under dry (O2) or wet (O2 + H2O) oxygen atmospheres, at total pressures of 3.0 or 10.0 mbar. The obtained results evidence that, upon dry O2 at 10.0 mbar, the initial nucleation of CoO occurs, followed by its progressive oxidation to Co3O4 during the subsequent growth stages. In a different way, cobalt monoxide can be selectively obtained at 3.0 mbar. In all cases, water vapor acts as an oxidant towards cobalt, favoring the formation of Co3O4 phases with a more pronounced {111} and {110}-type faceting. Structural, compositional and morphological characterization evidences the possibility of obtaining high purity CoO/Co3O4 systems with tailored morphological features, from films to columnar nanostructures, thus highlighting the potential and versatility of the proposed synthetic strategy.