Supported fluorine-doped alpha-Fe2O3 nanomaterials were synthesized by Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) at temperatures between 300 and 500 degrees C, using a fluorinated iron(II) diketonate-diamine compound as a single-source precursor for both Fe and F. The system structure, morphology and composition were thoroughly investigated by various characterization techniques, highlighting the possibility of controlling the fluorine doping level by varying the sole growth temperature. Photocatalytic H2 production from water/ethanol solutions under simulated solar irradiation evidenced promising gas evolution rates, candidating the present PE-CVD approach as a valuable strategy to fabricate highly active supported materials.

The development of quasi-1D Co3O4/ZnO nanocomposites by a two-step plasma enhanced-chemical vapor deposition (PE-CVD) process is presented. Arrays of < 001 > oriented ZnO nanorods were first grown on Si(100) and subsequently used as templates for the PE-CVD of Co3O4, whose amount was tailored as a function of deposition time. The obtained composites were thoroughly characterized by means of a multitechnique approach, involving field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDXS), micro-Raman and Fourier-transform infrared (FT-IR) spectroscopies, X-ray photoelectron and X-ray excited Auger electron spectroscopies (XPS, XE-AES), glancing incidence X-ray diffraction (GIXRD), and reflection high energy electron diffraction (RHEED). The use of moderate deposition temperatures (<= 300 degrees C), together with the unique activation provided by nonequilibrium plasmas, prevented state reactions between the two oxides and promoted Co3O4 growth on the tips of vertically aligned ZnO nanostructures. In particular, the resulting quasi-1D Co3O4/ZnO composites were characterized by an interface epitaxial-like relationship, an important issue for the development of semiconductor-based functional nanosystems. Photoinduced hydrophilic (PH) and photocatalytic (PC) performances of the present nanocomposites were preliminarily investigated, showing attractive results toward the possible fabrication of advanced smart materials.

In the broad scenario of multi-component nanomaterials, oxide-based systems are of primary technological importance for various applications of current interest, spanning from optoelectronics to catalysis, from chemical sensing to energy conversion and storage. Such a broad range of functional utilizations results from the joint features of nano-organized systems and the synergistic combination of constituent properties, which, in turn, can be tailored by means of flexible and scalable preparative strategies. An amenable synthetic option potentially meeting these standards is Chemical Vapor Deposition (CVD), either as such or in combination with other fabrication routes. To this regard, the present highlight provides an overview on the CVD-based growth and applicative potential of oxide-based nanocomposite systems. Special attention is devoted to three different categories, i.e. metal/oxide, oxide/oxide and carbon/oxide nanomaterials. For each of them, selected results on synthesis/applications of composite architectures with tailored morphology are presented, trying to address actual challenges and future trends in the field.

The application of new zirconium precursors for the fabrication of ZrO2 and ZrN thin films by metalorganic chemical vapor deposition (MOCVD) is presented. The all-nitrogen coordinated Zr precursors exhibit improved thermal properties for vapor phase fabrication of thin films. The growth of ZrO2 thin films was realized by the combination of the Zr complex with oxygen, while the formation of ZrN thin films was achieved for the first time employing a single source precursor (SSP) approach. This was enabled by the presence of nitrogen containing ligands which contributes to the formation of the ZrN phase without the need for any additional nitrogen source in contrast to classical film growth processes for ZrN thin films. In the first step the newly developed precursors were evaluated thoroughly for their use in MOCVD applications, and in the next step they were utilized for the growth of ZrO2 and ZrN thin films on Si(100) substrates. Polycrystalline ZrO2 films that crystallized in the monoclinic phase and the fcc-ZrN films oriented in the (200) direction were obtained, and their structure, morphology, and composition were analyzed by a series of techniques. This work shows the potential of tuning precursors for vapor phase fabrication of Zr containing thin films with a goal of obtaining two different classes of material systems (ZrO2 and ZrN) using one common precursor.

The application of new zirconium precursors for the fabrication of ZrO2 and ZrN thin films by metalorganic chemical vapor deposition (MOCVD) is presented. The all-nitrogen coordinated Zr precursors exhibit improved thermal properties for vapor phase fabrication of thin films. The growth of ZrO2 thin films was realized by the combination of the Zr complex with oxygen, while the formation of ZrN thin films was achieved for the first time employing a single source precursor (SSP) approach. This was enabled by the presence of nitrogen containing ligands which contributes to the formation of the ZrN phase without the need for any additional nitrogen source in contrast to classical film growth processes for ZrN thin films. In the first step the newly developed precursors were evaluated thoroughly for their use in MOCVD applications, and in the next step they were utilized for the growth of ZrO2 and ZrN thin films on Si(100) substrates. Polycrystalline ZrO2 films that crystallized in the monoclinic phase and the fcc-ZrN films oriented in the (200) direction were obtained, and their structure, morphology, and composition were analyzed by a series of techniques. This work shows the potential of tuning precursors for vapor phase fabrication of Zr containing thin films with a goal of obtaining two different classes of material systems (ZrO2 and ZrN) using one common precursor.

The present work focuses on the X-ray Photoelectron Spectroscopy (XPS) and X-ray Excited Auger Electron Spectroscopy (XE-AES) of a Co3O4/ZnO nanosystem. The composite material was obtained via a two-step Plasma Enhanced-Chemical Vapor Deposition (PECVD) process in Ar/O2 mixtures, consisting in the initial deposition of ZnO and the subsequent growth of Co3O4 onto the pristine matrices. Zn(ketoimi)2 (ketoimi = [CH3O(CH2)3NC(CH3)=C(H)C(CH3)=O]) and Co(dpm)2 (dpm = 2,2,6,6-tetramethyl-3,5-heptanedionate) were used as zinc and cobalt precursors, respectively. In particular, strongly 〈001〉 oriented ZnO was grown at 300 °C, followed by the deposition of Co3O4 at 200 °C, applying a radio-frequency (RF) power of 20 W. Structural, morphological and compositional investigations were performed by Glancing Incidence X-ray Diffraction (GIXRD), Field Emission-Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray Spectroscopy (EDXS). Surface XPS and XE-AES analyses were carried out to study in detail the system O 1s, Zn 2p3/2, Zn 3p and Co 2p core levels, as well as the Zn and Co Auger peaks. The obtained results evidenced the formation of a composite material, in which ZnO and Co3O4 preserved their chemical identity.

Plasma processing represents an attractive and versatile option for the fabrication of low-dimensional nanomaterials, whose chemical and physical properties can be conveniently tailored for the development of advanced technologies. In particular, Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) is an appealing route to multi-functional oxide nanoarchitectures under relatively mild conditions, owing to the unique features and activation mechanisms of non-equilibrium plasmas. In this context, the potential of plasma-assisted fabrication in advanced nanosystem development is discussed. After a brief introduction on the basic categories of plasma approaches, the perspectives of application to CVD processes are commented, reporting on the growth and characterization of Co3O4 nanomaterials as a case study. Besides examining the interrelations between the material properties and the synthesis conditions, special focus is given to their emerging applications as catalysts for photo-assisted hydrogen production and solid state gas sensors.

p-Type Co3O4 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 Co3O4 results in a remarkable performance improvement with respect to the corresponding undoped oxide, highlighting F-doped Co3O4 films as highly promising systems for hydrogen generation. Notably, the obtained yields were among the best ever reported for similar semiconductor-based photocatalytic processes.

Ag/ZnO nanocomposites were developed by a plasma-assisted approach. The adopted strategy exploits the advantages of Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) for the growth of columnar ZnO arrays on Si(100) and Al2O3 substrates, in synergy with the infiltration power of the Radio Frequency (RF)-sputtering technique for the subsequent dispersion of different amounts of Ag nanoparticles (NPs). The resulting composites, both as-prepared and after annealing in air, were thoroughly characterized with particular attention on their morphological organization, structure and composition. For the first time, the above systems have been used as catalysts in the production of hydrogen by photo-reforming of alcoholic solutions, yielding a stable H2 evolution even by the sole use of simulated solar radiation. In addition, Ag/ZnO nanocomposites presented an excellent response in the gas-phase detection of H2, opening attractive perspectives for advanced technological applications.

Co3O4-based nanosystems were prepared on polycrystalline Al2O3 by plasma enhanced-chemical vapor deposition (PE-CVD), at temperatures ranging between 200 and 400°C. The use of two different precursors, Co(dpm)2 (dpm=2,2,6,6-tetramethyl-3,5-heptanedionate) and Co(hfa)2·TMEDA (hfa=1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA=N,N,N′,N′-tetramethylethylenediamine) enabled the synthesis of undoped and fluorine-doped Co3O4 specimens, respectively. A thorough characterization of their properties was performed by glancing incidence X-ray diffraction (GIXRD), atomic force microscopy (AFM), field emission-scanning electron microscopy (FE-SEM), secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS). For the first time, the gas sensing properties of such PE-CVD nanosystems were investigated in the detection of ethanol and acetone. The results show an appreciable response improvement upon doping and functional performances directly dependent on the fluorine content in the Co3O4 system.

Co3O4 thin films were grown on MgO(100) and MgAl2O4(100) by plasma enhanced-chemical vapor deposition (PE-CVD) from the [Co(dpm)(2)] precursor. Depositions on both single crystal substrates were performed from Ar/O-2 plasmas at temperatures between 100 and 400 degrees C in order to tailor the chemical and physical properties of the synthesized films. The composition, morphology and structure of the Co3O4 systems were thoroughly analyzed by XPS, SIMS, FE-SEM and bidimensional XRD. The obtained results evidenced the formation of high-purity and strongly oriented Co3O4 thin films, with features dependent on the used substrate and the adopted growth temperature.

Two closely related bis(ketoiminato) zinc precursors, which are air stable and possess favorable properties for metal-organic (MO)CVD, are successfully employed for the growth of ZnO films on silicon and borosilicate glass substrates at temperatures between 400 and 700 degrees C. The as-deposited films are investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), nuclear reaction analysis (NRA), as well as by UV-vis absorption spectroscopy and photoluminescence (PL) measurements. The structure, morphology, and composition of the as-grown films show a strong dependence on the substrate temperature. The formation of pure and (001)-oriented wurtzite-type stoichiometric ZnO is observed. PL measurements are performed both at room temperature and 77 K, revealing a defect-free emission of ZnO films.

Strongly c-axis oriented ZnO nanorod arrays were grown on Si(100) by plasma enhanced-chemical vapor deposition (PE-CVD) starting from two volatile bis(ketoiminato) zinc(II) compounds Zn[(R')NC(CH3)=C(H)C(CH3)=O](2), with R' = -(CH2)(x)OCH3 (x = 2, 3). A systematic investigation of process parameters enabled us to obtain the selective formation of ZnO nanorods with tailored features, and provided an important insight into their growth mechanism. The morphology, structure, and composition or the synthesized ZnO nanosystems were thoroughly analyzed by field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDXS), glancing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (X PS). and transmission electron microscopy (TEM). Photoluminescence (PL) measurements were carried out to gain information on the optical properties. Specifically, one-dimensional (ID) ZnO architectures could be grown on Si(100) substrates at temperatures as low as 200-300 degrees C and radio frequency (RF)-power values of 20 W, provided that a sufficiently high mass supply to the growth surface was maintained. To the best of our knowledge, the present work reports the mildest preparation conditions ever appeared in the literature for the PE-CVD of ZnO nanorods, a key result in view of potential large-scale technological applications.

In this work, 1D ZnO nano-assemblies were prepared on Al2O3 substrates by plasma enhanced-chemical vapor deposition (PE-CVD), and characterized in their morphology and chemical composition by field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDXS) and X-ray photoelectron spectroscopy (XPS). For the first time, the sensing performances of PE-CVD ZnO nanosystems were tested in the detection of toxic/combustible gases (CO, H2 and CH4), revealing very good responses already at moderate working temperatures. In particular, carbon monoxide and hydrogen detection was possible already at 100 °C, whereas methane sensing required a minimum temperature of 200 °C. The performances of the present ZnO nanosystems, that make them attractive candidates for technological applications, are presented and discussed in terms of their unique and controllable morphological organization.

Supported ZnO nanorods with a different degree of preferential orientation and tunable morphological features were grown on Si(100) by plasma enhanced-chemical vapor deposition. The combined investigation of the synthesized arrays by RHEED and FE-SEM enabled a thorough insight into their structural properties and growth mechanism, whose control is a key issue in view of potential technological applications.

Two new bis(ketoiminato)zinc(II) compounds that show excellent precursor properties for the chemical vapor deposition (CVD) of zinc oxide materials are presented. The synthesis of the ketoiminato zinc complexes [Zn{[(CH2)(x)-OCH3]NC(CH3)=C(H)C(CH3)=O}(2)] (1: x = 2; 2: x = 3) is straightforward and can easily be scaled up. Compounds 1 and 2 were analyzed by H-1 and C-13 NMR spectroscopy, elemental analysis, single-crystal X-ray diffraction analysis, and electron ionization mass spectrometry. The compounds exist as monomers with a distorted tetrahedral zinc center. Thermogravimetric studies, sublimation, and solubility tests re-veal very promising properties for metal organic CVD related applications. Preliminary metal organic CVD experiments with the use of compound 1 were performed as a screening for the suitability of the new bis(ketoiminato)zinc complexes as precursors for the growth of ZnO thin films in the presence of oxygen. The films were characterized by Xray diffraction, scanning electron microscopy, energy dispersive analysis of X-ray, and Rutherford backscattering measurements. The as-deposited ZnO films were stoichiometric; the crystalline films exhibited strong preferred orientation along the c-axis.

The growth of one-dimensional (1D) semiconducting materials for advanced functional applications is the current focus of various cutting-edge research activities. In this context, 1D ZnO nanosystems, such as nanowires and nanorods (NRs), are extremely appealing targets due to their broad variety of attractive properties, resulting from the synergy between their ultrahigh surface-to-volume ratio, inherent anisotropy and quantum confinement of charge carriers. Such unique characteristics render 1D ZnO nanosystems appealing multi-functional modules for various utilizations, such as electron field emitters, gas sensors, lasers, piezoelectrics and photovoltaic cells. Recently, ZnO NR arrays have also received considerable attention for their advanced photo-activated functions, regarding, in particular, photo-induced superhydrophilicity (PSH) and photocatalysis (PC), that pave the way to the development of stimuliresponsive systems. In this context, the growth of supported ZnO NRs with tailored properties plays a strategic role, since such arrays represent very favorable architectures for light trapping and reduce undesired particle aggregation frequently observed for powdered materials. In addition, for PSH and PC applications, a high surface-to-volume ratio enables a faster arrival of photo-generated electrons and holes to the NRs surface, reducing detrimental recombination phenomena. The functional performance of ZnO NRs is directly dependent on the availability of proper synthetic strategies enabling a fine control of their morphology and spatial organization. 5a,6] Among the various approaches, chemical vapor deposition (CVD) is one of the most versatile techniques due to its intrinsic experimental flexibility and to the use of metalorganic precursors endowed with ad hoc chemical and physical properties. In particular, activation of both gas-phase and surface processes by means of non-equilibrium plasmas (plasma-enhanced CVD, PE-CVD) promotes alternative reaction pathways under softer conditions than in thermal CVD, enabling one to modulate deposition surface chemistry and to obtain 1D nanostructures with tailored properties. Herein, we report on the PE-CVD of supported ZnO nanorod arrays on Si(100) substrates from two recently developed bis(ketoiminato) zinc (II) compounds, Zn[(R’)NC(CH3)= C(H)C(CH3)=O]2, with R’= (CH2)2OCH3 (1) or (CH2)3OCH3 (2). The selective growth of ZnO NR arrays was performed from Ar/O2 plasmas at 200 and 300 8C (see Figure 1, Table 1 and Supporting Information), the lowest temperatures reported in the literature for the PE-CVD of such 1D architectures. Special attention was devoted to the interrelations between PSH and PC activity of the obtained 1D ZnO systems and their morphological characteristics. PSH properties were analyzed by monitoring the evolution of water contact angle (CA) as a function of the UV irradiation time. The self-cleaning activity of the synthesized NRs was investigated through a novel quantitative and highly sensitive PC method recently developed by some of us, consisting of the determination of a terephthalic acid (TPA) oxidation product, that is, hydroxyterephthalic acid (HOTPA).

ZnO nanorod assemblies were grown by plasma-enhanced chemical vapor deposition on polycrystalline Al2O3 at 200–300 °C, resulting in urchin-like 1-D ZnO NR arrays with a strong c-axis orientation. Their outstanding gas sensing responses and very low detection limits highlight the potential of the present systems in the production of high efficiency chemical sensors for a variety of applications.

Novel mixed amido/imido/guanidinato complexes of niobium are reported. The complexes were synthesized by insertion of two equivalents of di-isopropylcarbodiimide (i-Pr-cdi) or bis-cyclohexylcarbodiimide (Cy-cdi) respectively, into the niobium-amido bonds of [Nb(NR(2))(3)(N-t-Bu)] (, R = Me; , R = Et) starting out from [NbCl(3)(N-t-Bu)(py)(2)] and the respective LiNR(2) reagent (py = pyridine). Four representative examples of these mixed ligand amido/imido/guanidinato compounds were synthesized and were characterized by (1)H-NMR, (13)C-NMR, (15)N-NMR, CHN-analysis, mass spectrometry and infra-red spectroscopy. The molecular structures of [Nb(NR(2)){eta(2)-(i-Pr-N)(2)C(NR(2))}(2)(N-t-Bu)] (, R = Me; , R = Et) in the solid state were determined by single-crystal X-ray diffraction studies and are discussed together with the molecular structure of the starting compound [Nb(NMe(2))(3)(N-t-Bu)] (). The thermal properties of the new compounds depend on the substitution at the guanidinato ligand. Complexes of i-Pr-cdi are significantly more volatile than complexes of Cy-cdi as revealed by thermogravimetric analysis. Preliminary experiments using as a single-molecule source for metal-organic chemical vapour deposition (MOCVD) in the absence of ammonia indicate the formation of the stoichiometric, and surprisingly carbon-free, cubic niobium nitride phase.