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Titania-supported vanadia (VOx/TiO2) catalysts exhibit outstanding catalytic in a number of selective oxidation and reduction processes. In spite of numerous investigations, the nature of redox transformations of vanadium and titanium involved in various catalytic processes remains difficult to detect and correlate to the rate of products formation. In this work, we studied the redox dynamics of active sites in a bilayered 5% V2O5/15% TiO2/SiO2 catalyst (consisting of submonolayer VOx species anchored onto a TiOx monolayer, which in turn is supported on SiO2) during the oxidative dehydrogenation of ethanol. The VOx species in 5% V2O5/15% TiO2/SiO2 show high selectivity to acetaldehyde and an ca. 40 times higher acetaldehyde formation rate in comparison to VOx species supported on SiO2 with a similar density. Operando time-resolved V and Ti K-edge X-ray absorption near-edge spectroscopy, coupled with a transient experimental strategy, quantitatively showed that the formation of acetaldehyde over 5% V2O5/15% TiO2/SiO2 is kinetically coupled to the formation of a V4+ intermediate, while the formation of V3+ is delayed and 10–70 times slower. The low-coordinated nature of various redox states of VOx species (V5+, V4+, and V3+) in the 5% V2O5/15% TiO2/SiO2 catalyst is confirmed using the extensive database of V K-edge XANES spectra of standards and specially synthesized molecular crystals. Much weaker redox activity of the Ti4+/Ti3+ couple was also detected; however, it was found to not be kinetically coupled to the rate-determining step of ethanol oxidation. Thus, the promoter effect of TiOx is rather complex. TiOx species might be involved in a fast electron transport between VOx species and might affect the electronic structure of VOx, thereby promoting their reducibility. This study demonstrates the high potential of element-specific operando X-ray absorption spectroscopy for uncovering complex catalytic mechanisms involving the redox kinetics of various metal oxides., JACS Au, 2 (3), ISSN:2691-3704

Due to the development in science field which gives not only benefit but also introducesundesirable pollution to the environment. This pollution is due to poor discharge activities of industrial effluents into the soil and water bodies, surface run off from fields of agricultural lands, dumping of untreated wastes by municipalities, and mining activites, which deteriorates the cardinal virtue of our environment and causes menace to human health and life. Heavy metal(s), a natural constituent on earth's crust and economic important mineral, due to its recalcitrant effects creates heavy metal pollution which affects food chain and also reduces the quality of water. For this, many researchers have performed studies to find efficient methods for wastewater remediation. One of the most promising methods from economic point of view is adsorption, which is simple in design, but leads to use of a wide range of adsorbents and ease of operations. Due to advances in nanotechnology, many nanomaterials were used as adsorbents for wastewater remediation, because of their efficiency. Many researchers have reported that nanoadsorbents are unmitigatedly a fruitful solution to address this world's problem. This review presents a potent view on various classes of nanoadsorbents and their application to wastewater treatment. It provides a bird's eye view of the suitability of different types of nanomaterials for remediation of wastewater and Backspace gives up-to-date information about polymer based and silica-based nanoadsorbents.

Precisely positioning functionalized gold nanoparticles assemblies at planar donor-acceptor interfaces results in 14-fold enhancement of power conversion efficiency in P3HT/PCBM organic solar cells on plastic (ITO/PET) substrates. This result has been achieved by employing naphthalenethiol-capped gold nanoparticles (NT-Au-NPs) produced by laser ablation in liquid and size varied in the 10-30 nm range. Upon surface functionalization with the aromatic thiol, these particles self-assemble in submicrometer aggregates, which give increased light scattering. When these aggregates are deposited in the planar heterojunction between the donor and the acceptor systems, the localized scattering leads to a larger exciton formation just in the region of interest for charge transfer. (Graph Presented).

Biphasic photocatalytic powders consisted of hydroxyapatite (HA) and titanium dioxide (TiO(2)) were prepared by precipitation of HA in presence of TiO(2) (Evonik-Degussa P25). Depending on the volume ratio between HA and TiO(2) in the initial solution the materials showed different textural properties. Aggregates consisted of spherical particles were formed at low HA/TiO(2) ratio, while the decrease of the TiO(2) amount resulted in formation of needle and lath like particles. The specific surface area (ssa) of the composites was higher than the ssa of the pure components and increased with the decrease of the TiO(2) amount. The novel materials exhibited excellent activity in photocatalytic NO oxidation, while the activity in NO(2) removal, either by oxidation or by adsorption to the HA. was extremely low for the composites with volume ratio V(HA)/V(TiO2) more than 1. The selective behavior of these composites towards the two steps of the NO oxidation process was related to the preparation procedure followed. The composite with 50% (v/v) TiO(2) revealed higher center dot OH formation ability and photocatalytic activity in overall NO(x) removal than the pure TiO(2) component that was ascribed to the specific V(HA)/V(TiO2) ratio and growth of HA on the TiO(2) surface. (C) 2011 Elsevier B.V. All rights reserved. Applied Catalysis B-Environmental

International audience; Herein, we present the upscaled synthesis of nanoparticulate Li4Ti5O12 (LTO) by means of flame spray pyrolysis (FSP), yielding high phase purity and appropriate morphology for application as high-power lithium-ion anode material. Electrodes based on this optimized LTO nanopowder, carboxymethyl cellulose (CMC) as binder, and copper as current collector revealed excellent rate performance, providing specific capacities of 133, 131, 129, 127, 124, and 115 mAh g(-1) when applying C rates of 1C, 2C, 5C, 10C, 20C, and 50C, respectively. Targeting the commercial application of thus synthesized nanoparticles, we optimized also the electrode composition, comparing three different binding agents (CMC, PVdF, and poly(acrylic acid), PAA) and substituting the copper current collector by aluminum. The results of this comparative analysis show, that the combination of nanoparticulate LTO, CMC, and an aluminum current collector appears most suitable toward the realization of environmentally friendly and cost-efficient lithium-ion anodes, presenting very stable cycling performance for more than 1000 cycles at 10C without substantial capacity decay. (C) The Author(s) 2015. Published by ECS. All rights reserved.

A commercial TiO2 nanopowder, Degussa P25, was modified with several rare earth (RE) elements in order to extend its photocatalytic activity into the visible range. The mixtures were prepared via solid-state reaction of the precursor oxides, and thermally treated at high temperature (900 and 1000 degrees C), with the aim of investigating the photocatalytic activity of the thermally treated samples. This thermal treatment was chosen for a prospective application as a surface layer in materials that need to be processed at high temperatures. The photocatalytic activity (PCA) of the samples was assessed in gas-solid phase - monitoring the degradation of isopropanol (IPA) - under visible-light irradiation. Results showed that the addition of the REs lanthanum, europium and yttrium to TiO2 greatly improved its photocatalytic activity, despite the thermal treatment, because of the presence of more surface hydroxyl groups attached to the photocatalyst's surface, together with a higher specific surface area (SSA) of the modified and thermally treated samples, with regard to the unmodified and thermally treated Degussa P25. The samples doped with La, Eu and Y all had excellent PCA under visible-light irradiation, even higher than the untreated Degussa P25 reference sample, despite their thermal treatment at 900 degrees C, with lanthanum producing the best results (i.e. the La-, Eu- and Y-TiO2 samples, thermally treated at 900 degrees C, had, respectively, a PCA equal to 26, 27 and 18 ppm h(-1) - in terms of acetone formation - versus 15 ppm h(-1) for the 900 degrees C thermally treated Degussa P25). On the other hand, Ce-TiO(2)s had no significant photocatalytic activity. (C) 2013 Elsevier Ltd. All rights reserved.

Thermal analysis (TA) techniques were applied in order to predict the influence of thermal treatment, on the photocatalytic performance of TiO2 materials prepared via sol-gel method in various temperatures between 250 and 600 A degrees C in different alcohols (methanol/ethanol). Calorimetric results showed that the formation of TiO2 is faster in methanol than in ethanol. TA patterns showed that slight differences observed in the thermal behavior of the material can affect both its textural and photocatalytic properties. The appearance of the endothermic peaks in the area of 250-450 A degrees C refer to crystallization of amorphous to crystalline phases or to the transformation of the less active rutile to the more active anatase phase. The results obtained from TG/DSC are in accordance to XRD results and SEM images. Thermal treatment affects the photocatalytic properties of the materials. Samples prepared in methanol showed better photocatalytic behavior than those in ethanol while the increase in temperature decreases the effectiveness of the materials. Journal of Thermal Analysis and Calorimetry

International audience; DC reactive sputtering was used to deposit titanium and tungsten-based metal/oxide periodic nanometric multilayers using pure metallic targets and Ar + O-2 gas mixture as reactive atmosphere. The innovative technique namely, the reactive gas pulsing process allows switching between the metal and oxide to prepare a periodic multilayered structure with various metalloid concentrations and nanometric dimensions. The same pulsing period was used for each deposition to produce metal-oxide periodic alternations close to 10 nm. Structure, crystallinity and chemical composition of these films were systematically investigated by Raman spectroscopy, X-ray diffraction and Energy-dispersiveX-ray spectroscopy techniques. The high resolution transmission electron microscopy allowed observing the sharpness of the metal/oxide interfaces and measuring the thickness of each kind of layers. Moreover, the crystalline structure of metal and metal oxide layers was also studied. The difference of reactivity between the two systems leads to periodic beta-W3O/a-WO3 and face-centered-cubic-TiO/a-TiO2 multilayers.

International audience; Non-equilibrium nitrogen DC-arc plasma treatment of a commercial TiO2 anatase nanopowder was examined to obtain nitrogen-doped TiO2. By using a non-thermal discharge at low current (150 mA) and high voltage (1200 V) using pure N2 gas, light yellowish-gray TiO2 powder was successfully obtained within a short period of 5-10 min. XPS and TEM-EELS studies confirmed the existence of doped nitrogen. Due to the relatively mild conditions (plasma power of 180 W), metastable anatase structure and fine crystallite size of TiO2 (ca. 10 nm) were maintained after the plasma treatment. The in-flight powder treatment system used in this study is promising for various type of powder treatment

Visible-light-activated yellow amorphousTiO2(yam-TiO2) was synthesised by a simple and organic-free precipitation method. TiN, an alternative precursor forTiO2preparation, was dissolved in hydrogen peroxide under acidic condition(pH∼1)adjusted by nitric acid. The yellow precipitate was obtained after adjusting pH of the resultant red brown solution to 2 withNH4OH. The BET surface area of this sample was 261 m2/g. The visible light photoactivity was evaluated on the basis of the photobleaching of methylene blue (MB) in an aqueous solution by using a 250 W metal halide bulb equipped with UV cutoff filter (λ>420 nm) under aerobic conditions. Yam-TiO2exhibits an interesting property of being both surface adsorbent and photoactive under visible light. It was assigned to theη2-peroxide, an active intermediate form of the addition ofH2O2into crystallinedTiO2photocatalyst. It can be concluded that an active intermediate form of titanium peroxo species in photocatalytic process can be synthesised and used as a visible-light-driven photocatalyst.