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Hypothesis If nanocrystals of such semiconductor as SnO2 and TiO2, which are not known as powerful adsorbents, have their surface modified by layer of V2O5, how will the adsorption properties be affected? Answering this question would provide a new set of surface properties to be designed by surface engineering of oxide nanocrystals. Experiments SnO2 and TiO2 colloidal nanocrystals were prepared by coupling sol-gel and solvothermal synthesis. By co-processing with V chloroalkoxide and subsequent heat-treatment at 400–500 °C, surface deposition of V2O5 layers was obtained. The methylene blue adsorption onto the prepared materials was tested and compared with the pure oxide supports. Cycling of the materials and analysis of the adsorption process was also investigated. Findings The V-modified nanocrystals extracted ∼80% methylene blue from 1.5 × 10−5 M aqueous solution after 15 min only, contrarily to pure materials, which took up only 30% of the dye even after 120 min. Comparison with pure commercial V2O5 showed that the peculiar adsorption properties were imparted by the surface deposition of the V2O5-like layers. This report demonstrates that new classes of adsorbing materials can be conceived by suitably coupling different metal oxides.

Photocatalysis-based technologies are currently striving to find a methodology able to selectively catch, and degrade specific organic contaminants. To solve this problem, we propose molecularly imprinted ZnO nanonuts as new nanomaterial. In this work, ZnO have been imprinted, through a chemical method, with one of the most diffused analgesic-antipyretic drugs: acetaminophen (commonly called “paracetamol”), today considered as an emergent environmental pollutant. The molecularly imprinted nanonuts have been characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) adsorption-desorption of N2, X-ray diffraction analyses (XRD), high-resolution transmission scanning electron microscopy (HR-S/TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Thanks to the accurate performed characterization, the interaction between ZnO and paracetamol has been elucidated. The photodegradation of paracetamol in aqueous solution has been demonstrated under UV light irradiation. The selectivity of the photodegradation process has been additionally investigated thanks to the comparison with the degradation of methyl orange (MO) and phenol, another two common water pollutants. Imprinted ZnO nanonuts have shown a great affinity and selectivity for the paracetamol, being able to degrade all the paracetamol present in the solution in 3 h. This work offers a new, economic, and easy way to prepare molecularly imprinted ZnO nanonuts with high specificity, relevant in the contexts of environmental protection.

In order to achieve a selective removal of specific pesticides from water, we synthesized, through the sol-gel technique, molecularly imprinted TiO2 photocatalysts with the only use of the standard reactants of the TiO2 sol-gel synthesis together with the pesticide molecules, without any addition of further reactants supports or matrices. It is a new, easy, smart and scalable method that avoid the multistep and solvent-consuming procedures, typical of the molecular imprinting. Two widely-used pesticides, i.e. the herbicide 2,4D, and the insecticide imidacloprid, were chosen as template for the molecular imprinting and as contaminants target for the photocatalytic tests. A remarkable enhancement of the photocatalytic activity was verified with the TiO2 imprinted with the corresponding pesticide-target. The selectivity of the photodegradation process was verified thanks to the comparison with the degradation of pesticides not-used as template. Furthermore, the eventual toxic effects of the molecularly imprinted materials were evaluated by biological tests. The combination of molecular imprinting with photocatalysis, here investigated for the first time with pesticides, it is a promising strategy to selectively catch (through the molecular imprinting process) and degrade (through the photocatalysis) specific organic contaminants from water.

Hybrid electric vehicles (HEV) are nowadays proving to be one of the most promising technologies for the improvement of the fuel economy of several transportation segments. As far as the on-road category is concerned, a wise selection of the powertrain design is needed to exploit the best energetic performance achievable by a HEV. Amongst the methodologies developed for comparing different hybrid architectures, global optimizers have demonstrated the capability of leading to optimal design solutions at the expense of a relevant computational burden. In the present paper, an innovative deep neural networks-based model for the prediction of tank-to-wheel carbon dioxide emissions as estimated by a Dynamic Programming (DP) algorithm is presented. The model consists of a pipeline of neural networks aimed at catching the correlations lying between the design parameters of a HEV architecture and the main outcomes of the DP, namely powertrain feasibility and tail pipe CO2 emissions. Moreover, an automatic search tool (AST) has been developed for tuning the main hyper-parameters of the networks. Interesting results have been registered by applying the pipeline to three databases related to three different HEV parallel architectures. The capability of the pipeline has been proved through an extensive testing campaign made up by multiple experiments. Classification performances above 91% as well as average regression errors below 1% have been achieved during an extensive set of simulations. The presented model could hence be considered as an effective tool for supporting HEV design optimization phases.

High temperature reverse-bias (HTRB), High temperature gate-bias (HTGB) tests and electrical DC characterization were performed on planar-SiC power MOSFETs which survived to accelerated neutron irradiation tests carried out at ChipIr-ISIS (Didcot, UK) facility, with terrestrial neutrons. The neutron test campaigns on the SiC power MOSFETs (manufactered by ST) were conducted on the same wafer lot devices by STMicroelectronics and Airbus, with different neutron tester systems. HTGB and HTRB tests, which characterise gate-oxide integrity and junction robustness, show no difference between the non irradiated devices and those which survived to the neutron irradiation tests, with neutron fluence up to 2× 1011 (n/cm2). Electrical characterization performed pre and post-irradiation on different part number of power devices (Si, SiC MOSFETs and IGBTs) which survived to neutron irradiation tests does not show alteration of the data-sheet electrical parameters due to neutron interaction with the device.

Due to rapid population growth and intensification of agricultural and industrial activities, a diverse array of hazardous pollutants is progressively entered in the aquatic system. Particularly, persistent organic contaminants such as pesticides, solvents, dyes, detergents and industrial chemicals, constitute a pressing ecological problem that poses a great threat to human health [1]. An eco-friendly and definitive process to eliminate contaminants from water is concerned on their complete mineralization by using photocatalytic approach [2], followed by an efficient and easily catalyst separation at the end of the process. In light of this, we have formulated a novel multifunctional super-adsorbent sponge based on poly-2-hydroxyethyl methacrylate/graphene oxide (pHEMA@GO) composite developed by a cryo-polymerization in water [3]. In addition, taking advantages by the hydroxyl pendant groups present on both HEMA and GO moieties, our strategy involves the use of the sponge as a platform to link covalently ZnO by using Atomic Layer Deposition (ALD). This step can provide them the ability to degrade pollutants via photocatalytic process after the adsorption.

This work reports on the ZnO thin films obtained by atomic layer deposition (ALD), at a deposition temperature down to 40 degrees C. The crystallinity of the material as a function of the film thickness and the deposition temperature was investigated. The photocatalytic performance was evaluated by the degradation of methylene blue (MB) dye in water under UV light irradiation. The effect of the film thickness and the deposition temperature on the photocatalysis was deeply elucidated. Once the optimized conditions (in terms of thickness and temperature) were found, the ALD process was transferred on a flexible polymeric substrate: polyethylene naphthalate (PEN). The photo-activity of the flexible materials was evidenced by the degradation of MB and phenols in water. The results demonstrate that low temperature growth by ALD can be fruitfully applied to synthesize flexible materials that can found applications in photocatalysis. (C) 2016 Elsevier B.V. All rights reserved.

Two-dimensional (2D) nanomaterials have received much attention in recent years, because of their unusual properties associated with their ultra-thin thickness and 2D morphology. Besides graphene, a new 2D material, molybdenum disulfide (MoS2), has attracted immense interest in various applications. On the other hand, ball-milling process provides an original strategy to modify materials at the nanometer scale. This methodology represents a smart solution for the fabrication of MoS2 nanopowders extremely-efficient in adsorbing water contaminants in aqueous solution. This work reports a comprehensive morphological, structural, and physicochemical investigation of MoS2 nanopowders treated with dry ball-milling. The adsorption performances of the produced nanopowders were tested using methylene blue (MB) dye and phenol in aqueous solution. The adsorption capacity as a function of ball-milling time was deeply studied and explained. Importantly, the ball-milled MoS2 nanopowders can be easily and efficiently regenerated without compromising their adsorption capacity, so to be reusable for dye adsorption. The eventual toxic effects of the prepared materials on microcrustacean Artemia salina were also studied. The present results demonstrate that ball-milling of MoS2 offers a valid method for large-scale production of extremely efficient adsorbent for the decontamination of wastewaters from several pollutants.

The incorporation of nanostructured photocatalysts in polymers is a strategic way to obtain novel water purification systems. This approach takes the advantages of: (1) the presence of nanostructured photocatalyst; (2) the flexibility of polymer; (3) the immobilization of photocatalyst, that avoids the recovery of the nanoparticles after the water treatment. Here we present ZnO-polymer nanocomposites with high photocatalytic performance and stability. Poly (methyl methacrylate) (PMMA) powders were coated with a thin layer of ZnO (80 nm thick) by atomic layer deposition at low temperature (80 °C). Then the method of sonication and solution casting was performed so to obtain the ZnO/PMMA nanocomposites. A complete morphological, structural, and chemical characterization was made by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses. The remarkable photocatalytic efficiency of the nanocomposites was demonstrated by the degradation of methylene blue (MB) dye and phenol in aqueous solution under UV light irradiation. The composites also resulted reusable and stable, since they maintained an unmodified photo-activity after several MB discoloration runs. Thus, these results demonstrate that the proposed ZnO/PMMA nanocomposite is a promising candidate for photocatalytic applications and, in particular, for novel water treatment.

A stepwise surface functionalization procedure, based on hybrid covalent and non-covalent approach is herein proposed to anchor tetra-anionic meso-tetrakis(4-sulfonatophenyl)porphyrin on ZnO nanorods. Carboxyalkylphosphonic acids have been proven effective to form stable self-assembled monolayers through the surface grafting of –PO 3 H 2 headgroups. The exposed carboxylic functionalities are suitable for the successful grafting of cationic poly- l -lysine that drives, in water, the non-covalent anchoring of the anionic porphyrin. A stepwise surface characterization, provided by X-ray photoelectron spectroscopy, elucidates the multilayers deposition and surface composition after each process step, thus, giving interesting insights on the chemical speciation of the exposed functionalities. UV–vis spectroscopy confirms the role of ZnO morphology to increase the porphyrin loading onto the investigated surfaces. The proposed approach is effective to achieve deposition of anionic porphyrins on ZnO nanostructures and combines the robustness of covalent functionalization with the versatility and full reversibility of the non-covalent strategies.

The successful transferring of a porphyrin complex assembly from a solution to a solid surface is important for an economical development of functional materials, biomaterials, and sensing devices. The understanding of the mechanisms and factors that drive spontaneous and stable deposition, in water, of porphyrins (and their complex species) onto inorganic surfaces paves the way for a straightforward and environmentally friendly noncovalent functionalization of solid surfaces. Here, we show that surface charge considerations need to be carefully considered if water-soluble porphyrin derivatives have to be successfully immobilized onto zinc oxide (ZnO) layers deposited on glass. In particular, it will be demonstrated that the electrostatics of the glass support has a central role in driving the layering of charged (anionic and cationic) porphyrin derivatives. Finally, our results underline the robustness and versatility of the noncovalently driven deposition—in terms of both reproducibility and stability o...

Selective oxidation of CO in H 2 -rich stream was studied on iron oxide supported Au catalysts prepared by deposition-precipitation (AuDP) or coprecipitation (AuCP) and for comparison on commercial gold reference catalyst (AuRef), investigating in detail the effect of catalyst pretreatment towards the catalytic performance. On AuDP and AuCP samples CO conversion strongly decreased on increasing calcination temperature. On the AuRef sample the influence of calcination was, instead, less evident. On all tested catalysts a higher reduction temperature resulted in a lower CO conversion, the effect of reduction on catalysts activity exceeding that of calcination. On all samples selectivity towards CO oxidation decreased appreciably on increasing reaction temperature. The dependence of selectivity from pretreatment was negligible. On the basis of characterization data (H 2 -TPR, XRD, TEM) it was pointed out that, provided gold particles are small enough to be able to activate CO and H 2 , the catalytic behaviour of the Au/iron oxide system in the PROX reaction is strongly related to the support phase, being sensitive to the microcrystalline structure and the oxidation state of the iron oxide. CO oxidation activity of different iron oxide species was found in the order: ferrihydrite > hematite > magnetite. It was concluded that on Au/iron oxide the PROX reaction occurs through a Mars-van Krevelen type mechanism which involves lattice oxygen of the iron oxide and CO and H 2 adsorbed on gold particles.

A synthetic strategy for the covalent anchoring of nickel β-diketonate complexes on Si(1 0 0) has been examined. Engineered Si(1 0 0) surfaces were prepared by the Si-grafting of 10-undecylenic acid methyl ester followed by hydrolysis of the ester to free the carboxylic functions suited for the anchoring of the Ni complex. Bis(pentane-2,4-dionate)Ni(II) was bonded to the functionalized surface from the gas phase by the exchange of the acetylacetonate ligand with the grafted acid. The surface density of the anchored Ni complex was controlled by tuning the surface concentration of carboxylic groups adopting a mixed monolayer of undecylenic acid and 1-decene used as a spectator spacer. The nickel decorated silicon surfaces were characterized by attenuate total reflectance infrared absorption spectroscopy (ATR-IRAS) and angle resolved X-ray photoelectron spectroscopy (AR-XPS).

For this study, we originally realized ZnO nanofibers (similar to 50 nm in mean radius) mixed with Pt nanoparticles (similar to 30 nm in mean radius), prepared by pulsed laser ablation in liquid, and investigated their photocatalytic performance. The material was synthesized by the simple electrospinning method coupled with subsequent thermal treatments. Methylene blue was employed as a representative dye pollutant to evaluate the photocatalytic activity of the nanofibers. It was found that the Pt-ZnO fibers exhibit a photodegradation reaction rate that is similar to 40 % higher than the one obtained for reference ZnO fibers. These encouraging results demonstrate that Pt-ZnO nanofibers can be fruitfully applied for environmental applications.

Cysteine is a sulfur-containing amino acid that easily coordinates to soft metal ions and grafts to noble metal surfaces. Recently, chiroptical activity of Ag+/cysteine coordination polymers has been widely studied, while, on the other hand, the appearance of a plasmon-enhanced circular dichroic signal (PECD) at the plasmonic spectral region (lambda > 400 nm) has been observed for AgNPs capped with chiral sulfur-containing amino acids. These two events are both potentially exploited for sensing applications. However, the presence of Ag+ ions in AgNP colloidal solution deals with the competition of cysteine grafting at the metal NP surface and/or metal ion coordination. Herein we demonstrate that the chiroptical activity observed by adding cysteine to AgNP colloids prepared by pulsed laser ablation in liquids (PLAL) is mainly related to the formation of CD-active Ag+/cysteine supramolecular polymers. The strict correlation between supramolecular chirality and hierarchical effects, driven by different chemical environments experienced by cysteine when different titration modalities are used, is pivotal to validate cysteine as a fast and reliable probe to characterize the surface oxidation of AgNPs prepared by pulsed laser ablation in liquids by varying the laser wavelengths.

A multistep route for the covalent anchoring of (5-amino-1,10-phenanthroline)tris(dibenzoylmethane)europium(III) molecules on silicon (100) has been developed. The anchoring route consists of Si functionalization with N-hydroxysuccinimide (NHS) activated carboxylic acid, followed by nucleophilic substitution at the carboxylic acid sites. Characterization of the resulting Si based hybrid materials was achieved by using several complementary techniques: X-ray photoelectron spectroscopy (XPS), attenuated total reflection FTIR spectroscopy (ATR-FTIR), AFM and fluorescence spectroscopy. Comparison of results obtained for NHS activated Si surfaces with those of inert alkyl functionalized Si surfaces proved the covalent anchoring of the Eu complex and ruled out the presence of physisorbed Eu species. The 1.8 nm thickness of the grafted layer, estimated by atomic-force lithography, is compatible with the presence of the anchored complex on the surface. Fluorescence measurements proved that luminescence properties are retained in the grafted complex.

In this paper we report on the in situ synthesis of photo luminescent and patterned polyvinyl chloride (PVC) films, doped with cerium chloride. The precursor of the doping agent is the Tris(2-4 pentanedionate)cerium(III) 3H2O, Ce(acac)3, which absorbs UV and visible light. The PVC is both the photochemical source of chloride ion and the rigid matrix where the CeCl3 luminescent particles are dispersed. The PVC films containing cerium complex in the concentration range 0–3% w/w did not exhibit luminescence over 320 nm. After irradiation at 254 nm, the films of pure PVC exhibited luminescence emission with a maximum at about 420 nm, by excitation at 300 nm, due to the presence of polyenes, likely formed by PVC photodehydrochlorination. In PVC films, containing cerium complex, the HCl photoproduct underwent substitution of acac−, with the formation of CeCl3 and Hacac, detected by XPS and FTIR, respectively. Thus, these films exhibited the luminescence emissions of the cerium chloride at about 360 nm and that of the polyenes at 420 nm, that was evidenced well by excitation at 260 and 300 nm, respectively. The film luminescence appeared after an induction period which was a function of the Ce(acac)3 percentage and which was different for the two emitting species, as resulted by deconvolution of the luminescence band. The film irradiation by using a mask resulted in direct photopatterning. The luminescence emission occurred exclusively from directly irradiated zones. Thus no reaction occurred for the migration of reactive species. The FTIR analysis of the films, before and after sufficient irradiation to obtain luminescence, did not evidence significant changes in the chemical structure of the polymer and in the surface properties. Thus, this method can be used to provide PVC with luminescence without damaging side effect.

A simple and effective approach to fabricate extensive 3D ZnO nanoarchitectures on alkaline etched (100) Si substrates is presented. Textured silicon micropattern drives ZnO 1D growth on all the {111} exposed faces, resulting in sea sponge-likeZnO nanoarchitectures. The obtained 3D nanostructured ZnO is the result of a perfectly ordered array of continuous and crystalline ZnO nanorods, grown on the silicon pyramid {111} faces. The substrate orientation and the relative roughness, intrinsically derived by the alkaline silicon texturization, drive the preferential growth of one-dimensional ZnO nanorods. The ZnO nanorods photoluminescence spectra show, at room temperature, a narrow ultraviolet (UV) emission peak at 3.28 eV and a broad unstructured green band emission at 2.57 eV. These luminescence emissions are attributed to the near band-edge exciton transitions and to the defect emission, respectively. This original approach to fabricate high surface area ZnO nanoarchitectures presents the advantages of well established and reproducible methodologies of semiconductors industrial manufacturing (silicon micromachining and chemical vapor deposition), thus representing an easy scaling up solution to fabricate new ZnO-based nanomaterials.