Search results for " oxidation"
showing 10 items of 675 documents
Plasma Electrolytic Oxidation of TiZr Alloy in ZnONPs-Contained Solution: Structural and Biological Assessment
2020
Titanium (Ti) and its alloys with zirconium (Zr) due of their biological safety, lower elastic modulus and excellent corrosion resistance are the most attractive metallic materials for medical applications. Plasma electrolytic oxidation (PEO) is an environment-friendly process with rapid deposition of anodic oxide coating on the implant surface. PEO coating can incorporate different nanoparticles (NPs) into implant surface such as ZnO that stimulates osteoblast proliferation and mineralization, possesses antibacterial ability. The aim of current research was to evaluate structural and chemical properties of TiZr-alloy with addition ZnO NPs after the PEO in Ca/P solution. The alloy of the Ti…
Polymeric carbon nitride (C3N4) as heterogeneous photocatalyst for selective oxidation of alcohols to aldehydes
2018
Abstract Polymeric carbon nitride (C3N4) is a semiconductor material which is a very promising green photocatalyst with good physico-chemical properties and stability. It is a metal-free carbon based non-toxic material which can be easily obtained from earth-abundant components. The robustness and versatility of C3N4 as a photo-redox catalyst allows its use for selective oxidations by heterogeneous photocatalysis. This paper reviews the state of art in the application of C3N4 as heterogeneous photocatalyst for selective oxidation of alcohols to the corresponding aldehydes.
Honeycomb supported Co3O4/CeO2 catalysts for CO/CH4 emissions abatement: effect of low Pd-Pt content on the catalytic activity
2007
Abstract A structured Co3O4–CeO2 composite oxide, containing 30% by weight of Co3O4, has been prepared over a cordieritic honeycomb support. The bimetallic, Pd–Pt catalyst has been obtained by impregnation of the supported Co3O4–CeO2 with Pd and Pt precursors in order to obtain a total metal loading of 50 g/ft3. CO, CH4 combined oxidation tests were performed over the catalyzed monoliths in realistic conditions, namely GHSV = 100,000 h−1 and reaction feed close to emission from bi-fuel vehicles. The Pd–Pt un-promoted Co3O4–CeO2 is promising for cold-start application, showing massive CO conversion below 100 °C, in lean condition. A strong enhancement of the CH4 oxidation activity, between 4…
Comparison between preparative methodologies of nanostructured carbon nitride and their use as selective photocatalysts in water suspension
2017
Carbon nitride photocatalysts have been prepared by different methodologies, such as chemical ultrasonic irradiation (sonochemical treatment), hydrothermal and ball milling and thermoexfoliation, and have been used for the selective oxidation of 5-hydroxymethyl-2-furaldehyde (HMF) to form 2,5-furandicarboxyaldehyde (FDC) in water suspension both under UV and natural solar irradiation. The physico-chemical features of the photocatalysts have been studied by X-ray diffraction, infrared spectroscopy, UVâVis diffuse reflectance spectroscopy, photoluminescence spectroscopy, scanning electron microscopy, and specific surface area measurements. The results indicate that exfoliation of carbon nit…
Total oxidation of VOCs on mesoporous iron oxide catalysts: Soft chemistry route versus hard template method
2016
9 figures, 3 tables.-- Supplemantary information available
Electrochemical oxidation of organics at metal oxide electrodes: The incineration of oxalic acid at IrO2-Ta2O5 (DSA-O2) anode
2008
Abstract The electrochemical incineration of oxalic acid (OA) at Ti/IrO2–Ta2O5 (DSA-O2) anode was investigated to find the influence of the operative parameters on the performances of the process. Polarization curves and chronoamperometric measurements indicate the probable occurrence of a direct electrochemical oxidation of OA at the surface of the DSA anode. In incineration electrolyses, the performances of the process in terms of OA conversion and current efficiency dramatically depend on the adopted operative conditions. Interestingly, very high OA removal and current efficiency were obtained when the process was performed at relatively high temperatures (50 °C) or in the presence of Na…
Structure and the metal-support interaction of the Au/Mn oxide catalysts
2010
Gold catalysts with loading 1 and 10 wt % were-prepared by deposition precipitation method with urea over mesoporous manganese oxide, obtained through a surfactant-assisted procedure by using cetyltrimethylammonium bromide (CTAB), followed by treatment with sulphuric acid. For comparison, Au(10 wt %) was also deposited over commercial CeO2 and SiO2 supports. The materials were characterized by XRD and EXAFS at the Mn K and Au L-III edges and XPS. Moreover, the analyses were performed on the samples treated under 1%CO/He, at 250 degrees C for 90 min. The structural and surface results of the as prepared manganese oxide confirmed the formation of gamma-MnO2 along with some amorphous Mn3O4 upo…
Gas sensitive luminescence of ZnO coatings obtained by plazma electrolytic oxidation
2015
Abstract The ZnO coatings on Zn substrate were obtained using plasma electrolytic oxidation method. The XRD and SEM methods were used for structural and morphological characterization of obtained coatings. The luminescence of ZnO coatings were studied and compared with luminescence characteristics of ZnO single crystal. It is shown that luminescence intensity in ZnO defect band depends on oxygen concentration in ambient atmosphere. The effect is of interest for oxygen sensing based on ZnO coating luminescence.
Frictional behaviour of oxygen diffusion hardened titanium in dry sliding against Co–28Cr–5W–4Fe–3Ni–1Si cobalt alloy
2004
Abstract The results of conformal pin-on-disc tribological tests of a hard layer of the solid solution of oxygen in α-titanium sliding against a Co–28Cr–5W–4Fe–3Ni–1Si cobalt alloy counterspecimen are presented. The α-Ti(O) layer was diffusely produced over 2–8 h of oxidising in the superficial zone of a technical quality titanium specimen. The friction and wear responses of the system were recorded and the wear mechanisms were studied. Investigations of the material structure and chemical constitution in micro-areas of the titanium specimen, cobalt alloy counterspecimen and wear debris formed in dry sliding were performed with a Philips XL20 microscope equipped with an EDAX analyser. Crush…
Oxide-based nanomaterials for fuel cell catalysis:the interplay between supported single Pt atoms and particles
2017
The concept of single atom catalysis offers maximum noble metal efficiency for the development of low-cost catalytic materials. Among possible applications are catalytic materials for proton exchange membrane fuel cells. In the present review, recent efforts towards the fabrication of single atom catalysts on nanostructured ceria and their reactivity are discussed in the prospect of their employment as anode catalysts. The remarkable performance and the durability of the ceria-based anode catalysts with ultra-low Pt loading result from the interplay between two states associated with supported atomically dispersed Pt and sub-nanometer Pt particles. The occurrence of these two states is a co…