Nitrite anodic oxidation at Ni(II)/Ni(III)-decorated mesoporous SnO and its analytical applications.

Hydrothermally formed mesoporous SnO was used as a support for nickel chemical deposition and, after subsequent thermal treatment, a high specific surface area (36 m g) Ni/SnO material was obtained. XPS analysis has shown that in the Sn 3d region the spectrum is similar to that of pristine SnO, whereas Ni species are present on the surface as NiO, NiO and Ni(OH). Mixing Ni/SnO with a small amount of Black Pearls (BP) leads to a significant enhancement of the resulting Ni/SnO-BP composite activity for nitrite anodic oxidation, presumably due to the higher surface area (115 m g), to better electrical conductivity and to a certain contribution of the BP to an increase in surface density of the active sites.

Green synthesis of aminated hyaluronic acid-based silver nanoparticles on modified titanium dioxide surface: Influence of size and chemical composition on their biological properties.

This is the first report on an efficient, "environmentally friendly" chemical reduction method for the synthesis of aminated hyaluronic acid-based silver nanoparticles on the modified surface of titanium dioxide nanoparticles aimed for biological applications. Silver nanoparticles exhibit well-known physical-chemical and optical properties appropriate for different biological applications. Modifying the nanoparticles leads to a change in their expected bioactivity.

Influence of Ferroelectric Filler Size and Clustering on the Electrical Properties of (Ag-BaTiO)-PVDF Sub-Percolative Hybrid Composites.

The paper presents a study concerning the role of ferroelectric filler size and clustering in the dielectric properties of 20%BaTiO-80%PVDF and of 20% (2%Ag-98%BaTiO)-PVDF hybrid nanocomposites. By finite element calculations, it was shown that using fillers with ε > 10 does not provide a permittivity rise in the composites and the effective dielectric constant tends to saturate to specific values determined by the filler size and agglomeration degree. Irrespective of the ferroelectric filler sizes, the addition of metallic ultrafine nanoparticles (Ag) results in permittivity intensification and the effect is even stronger if the metallic nanoparticles are connected to a higher degree with the ferroelectric particles' surfaces.

Optoelectronic and stability properties of quasi-2D alkylammonium based perovskites.

Electronic and stability properties of quasi-2D alkylammonium perovskites are investigated using density functional theory (DFT) calculations and validated experimentally on selected classes of compounds. Our analysis is focused on perovskite structures of formula (A)(A')PbX, with large cations A = butyl-, pentyl-, hexylammonium (BA, PA, HXA), small cations A' = methylammonium, formamidinium, ethylammonium, guanidinium (MA, FA, EA, GA) and halogens X = I, Br, Cl. The role of the halogen ions is outlined for the band structure, stability and defect formation energies.

Electrocatalytic Properties of Mixed-Oxide-Containing Composite-Supported Platinum for Polymer Electrolyte Membrane (PEM) Fuel Cells.

TiO-based mixed oxide-carbon composite supports have been suggested to provide enhanced stability for platinum (Pt) electrocatalysts in polymer electrolyte membrane (PEM) fuel cells. The addition of molybdenum (Mo) to the mixed oxide is known to increase the CO tolerance of the electrocatalyst. In this work Pt catalysts, supported on TiMoO-C composites with a 25/75 oxide/carbon mass ratio and prepared from different carbon materials (C: Vulcan XC-72, unmodified and functionalized Black Pearls 2000), were compared in the hydrogen oxidation reaction (HOR) and in the oxygen reduction reaction (ORR) with a commercial Pt/C reference catalyst in order to assess the influence of the support on the electrocatalytic behavior.

Increasing Permittivity and Mechanical Harvesting Response of PVDF-Based Flexible Composites by Using Ag Nanoparticles onto BaTiO Nanofillers.

The role of Ag addition on the structural, dielectric, and mechanical harvesting response of 20%(Ag - (1 - )BaTiO) - 80%PVDF ( = 0, 2, 5, 7 and 27 vol.%) flexible composites is investigated. The inorganic fillers were realized by precipitating fine (~3 nm) silver nanoparticles onto BaTiO nanoparticles (~60 nm average size).

Carbon-Coated SiO Composites as Promising Anode Material for Li-Ion Batteries.

Porous silica-based materials are a promising alternative to graphite anodes for Li-ion batteries due to their high theoretical capacity, low discharge potential similar to pure silicon, superior cycling stability compared to silicon, abundance, and environmental friendliness. However, several challenges prevent the practical application of silica anodes, such as low coulombic efficiency and irreversible capacity losses during cycling. The main strategy to tackle the challenges of silica as an anode material has been developed to prepare carbon-coated SiO composites by carbonization in argon atmosphere.

Structural Details of BaTiO Nano-Powders Deduced from the Anisotropic XRD Peak Broadening.

In this study, nano-BaTiO (BTO) powders were obtained via the solvothermal method at different reaction times and were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The results were compared with those obtained for a larger crystallite size BTO powder (BTO-m). The sizes of the cuboid crystallites (as determined by XRD and TEM) ranged from about 18 to 24 nm, depending on the reaction time.

CuWO with CuO and Cu(OH) Native Surface Layers for HS Detection under in-Field Conditions.

The paper presents the possibility of detecting low HS concentrations using CuWO. The applicative challenge was to obtain sensitivity, selectivity, short response time, and full recovery at a low operating temperature under in-field atmosphere, which means variable relative humidity (%RH). Three different chemical synthesis routes were used for obtaining the samples labeled as: CuW1, CuW2, and CuW3.

Methane Combustion Using Pd Deposited on CeO-MnO/La-AlO Pellistors.

Pd deposited on CeO-MnO/La-AlO has been prepared as a sensitive material for methane (CH) detection. The effect of different amounts (1.25%, 2.

CeO:MnO Catalytic Micro-Converters Tuned for CH Detection Based on Catalytic Combustion under Real Operating Conditions.

Mesoporous CeO:MnO materials (3:7 and 7:3 molar ratio) were prepared by co-precipitation and deposited as porous thick films over alumina (AlO) planar substrate provided with Pt meander. The aim was oriented towards detecting low levels methane (CH) at moderate operating temperatures. Herein we demonstrated that the sensitivity of catalytic micro-converters (CMCs) towards a given peak of CH concentration corresponds to specific gas-surface interaction phenomena.

Decompensation of a Thoracic Meningioma Below the Operated Level: A Dramatic and Unexpected Complication.

Background: Paraplegia after lumbar spinal surgery has been previously described. It was generally provoked by a missed thoracic compression because of degenerative processes, arachnoid cyst, and spinal cord tumor such as meningioma. We describe here a case of a patient with neurofibromatosis type 2 (NF-2) with multiple spinal meningiomas that developed postoperative paraplegia because of decompensation of spinal cord compression below and far from the operated level.

Undoped SnO as a Support for Ni Species to Boost Oxygen Generation through Alkaline Water Electrolysis.

In this study, the synergistic behavior of Ni species and bimodal mesoporous undoped SnO is investigated in oxygen evolution reactions (OERs) under alkaline conditions without any other modification of the compositional phases or using noble metals. An efficient and environmentally friendly hydrothermal method to prepare bimodal mesoporous undoped SnO with a very high surface area (>130 m g) and a general deposition-precipitation method for the synthesis of well-dispersed Ni species on undoped SnO are reported. The powders were characterized by adsorption-desorption isotherms, TG-DTA, XRD, SEM, TEM, Raman, TPR-H, and XPS.

Imaging dopant distribution across complete phase transformation by TEM and upconversion emission.

Correlating dopant distribution to its optical response represents a complex challenge for nanomaterials science. Differentiating the "true" clustering nature from dopant pairs formed in statistical distribution complicates even more the elucidation of doping-functionality relationship. The present study associates lanthanide dopant distribution, including all significant events (enrichment, depletion and surface segregation), to its optical response in upconversion (UPC) at the ensemble and single-nanoparticle level.

Bulk Versus Surface Modification of Alumina with Mn and Ce Based Oxides for CH Catalytic Combustion.

This study presents the synthesis and characterization of lanthanum-modified alumina supported cerium-manganese mixed oxides, which were prepared by three different methods (coprecipitation, impregnation and citrate-based sol-gel method) followed by calcination at 500 °C. The physicochemical properties of the synthesized materials were investigated by various characterization techniques, namely: nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and H-temperature programmed reduction (TPR). This experimental study demonstrated that the role of the catalytic surface is much more important than the bulk one.

Behavior of Molybdenum⁻Vanadium Mixed Oxides in Selective Oxidation and Disproportionation of Toluene.

This study deals with the behavior of molybdenum⁻vanadium (Mo/V) mixed oxides catalysts in both disproportionation and selective oxidation of toluene. Samples containing different Mo/V ratios were prepared by a modified method using tetradecyltrimethylammonium bromide and acetic acid. The catalysts were characterized using several techniques: nitrogen adsorption⁻desorption isotherms, X-Ray diffraction (XRD), ammonia temperature-programmed desorption (TPD-NH₃), temperature-programmed reduction by hydrogen (H₂-TPR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier-transform infrared-spectroscopy (FTIR) and ultraviolet-visible spectroscopies (UV⁻VIS).

Near infrared emission properties of Er doped cubic sesquioxides in the second/third biological windows.

In the recent years, there is an extensive effort concentrated towards the development of nanoparticles with near-infrared emission within the so called second or third biological windows induced by excitation outside 800-1000 nm range corresponding to the traditional Nd (800 nm) and Yb (980 nm) sensitizers. Here, we present a first report on the near-infrared (900-1700 nm) emission of significant member of cubic sesquioxides, Er-LuO nanoparticles, measured under both near-infrared up-conversion and low energy X-ray excitations. The nanoparticle compositions are optimized by varying Er concentration and Li addition.

Heavy doping of ceria by wet impregnation: a viable alternative to bulk doping approaches.

To avoid the deleterious effects of dopant segregation, synthesis methods that facilitate a homogenous dopant distribution in the ceria lattice were employed. Though doping ceria by wet impregnation was also credited to induce a homogeneous solid solution even in the heavy regime (concentration ≥20%, A. Corma, P.

Sensors based on mesoporous SnO-CuWO with high selective sensitivity to HS at low operating temperature.

Development of new sensitive materials by different synthesis routes in order to emphasize the sensing properties for hazardous HS detection is one of a nowadays challenge in the field of gas sensors. In this study we obtained mesoporous SnO-CuWO with selective sensitivity to HS by an inexpensive synthesis route with low environmental pollution level, using tripropylamine (TPA) as template and polyvinylpyrrolidone (PVP) as dispersant/stabilizer. In order to bring insights about the intrinsic properties, the powders were characterized by means of a variety of complementary techniques such as: X-Ray Diffraction, XRD; Transmission Electron Microscopy, TEM; High Resolution TEM, HRTEM; Raman Spectroscopy, RS; Porosity Analysis by N adsorption/desorption, BET; Scanning Electron Microscopy, SEM and X-ray Photoelectron Spectroscopy, XPS.

Synthesis of Terephthalic Acid by p-Cymene Oxidation using Oxygen: Toward a More Sustainable Production of Bio-Polyethylene Terephthalate.

The synthesis of terephthalic acid from biomass remains an unsolved challenge. In this study, we conducted the selective oxidation of p-cymene (synthesized from biodegradable terpenes, limonene, or eucalyptol) into terephthalic acid over a Mn-Fe mixed-oxide heterogeneous catalyst. The impact of various process parameters (oxidant, temperature, reaction time, catalyst amount, oxygen pressure) on the selectivity to terephthalic acid was evaluated, and some mechanistic aspects were elucidated.

Defect induced tunable near infrared emission of Er-CeO2 by heterovalent co-dopants.

We investigate the effects of heterovalent co-dopants on the structural and emission properties of 1% Er-CeO2 nanoparticles. The CeO2 oxide host was selected on the basis of its fairly well-understood defect chemistry in either a pure or doped state. As a luminescent activator, Er is acknowledged as an interesting element due to its rich luminescence and excitation properties spanning the visible to near-infrared range.

Graphene from Alginate Pyrolysis as a Metal-Free Catalyst for Hydrogenation of Nitro Compounds.

Graphene obtained by pyrolysis of alginate at 900 °C under inert atmosphere and exfoliation is used as a metal-free catalyst for reduction of nitro to amino groups with hydrogen as a reagent. The process is general for aromatic and aliphatic, conjugated and isolated nitro groups, and occurs with low selectivity over hydrogenation of carbon-carbon double bonds.

Pure and almost pure NIR emission of Tm and Tm,Yb-CeO2 under UV, X-ray and NIR up-conversion excitation: key roles of level selective antenna sensitization and charge-compensation.

Herein, we report on the pure and almost pure near-infrared (NIR) emission at around 807 nm observed for Tm(Yb) (co)-doped CeO2 nanoparticles (NPs) under UV, X-ray and NIR up-conversion excitation. The optical responses are attributed to the low-lying charge-transfer of CeO2 that acts as a selective antenna sensitizer of the Tm (3)H4 emission and Yb doping that lowers the local symmetry at Tm sites and introduces additional phonon modes. Selective antenna sensitization is also observed for Er/Ho (Yb) (co)-doped CeO2 NPs.

Graphenes in the absence of metals as carbocatalysts for selective acetylene hydrogenation and alkene hydrogenation.

Catalysis makes possible a chemical reaction by increasing the transformation rate. Hydrogenation of carbon-carbon multiple bonds is one of the most important examples of catalytic reactions. Currently, this type of reaction is carried out in petrochemistry at very large scale, using noble metals such as platinum and palladium or first row transition metals such as nickel.