نتایج جستجو برای: vanadium v
تعداد نتایج: 309447 فیلتر نتایج به سال:
The study investigated photocatalytic water splitting for O₂ production under visible light irradiation using neodymium vanadium oxide (NdVO₄) and vanadium oxide (V₂O₅) hybrid powders. The results in a sacrificial agent of 0.01 M AgNO₃ solution were obtained, and the highest photocatalytic O₂ evolution was 2.63 μmol/h, when the hybrid powders were prepared by mixing Nd and V at a volume ratio o...
C-, V-doped TiO2 photocatalysts are prepared by a sol-gel process. These catalysts are highly active for the degradation of acetaldehyde both under visible irradiation (> 420 nm) and in the dark, especially for 2.0% V-containing co-doped TiO2. Characterization results suggest that vanadium ions are introduced both on the surface and into the bulk of TiO2. A free electron, induced by the formati...
The electrochemical reactivity of the cathode material Ag 4V 2O 6F 2 (SVOF) versus lithium, with a particular emphasis on the lithium insertion mechanism, was studied by means of the complementary techniques in situ X-ray diffraction, electron paramagnetic resonance, and high-resolution transmisssion electron microscopy. This study confirms the initial reports of a high capacity for SVOF of 148...
The reaction mechanism of methanol oxidation catalyzed by vanadium oxides on a silica support (V2O5/ SiO2) was investigated in a high-throughput operando reactor coupled with a Fourier transform-infrared (FT-IR) imaging system for rapid product analysis and six parallel, in situ Raman spectroscopy probes for catalyst characterization. Up to six V2O5/SiO2 catalysts with different vanadium loadin...
a simple, rapid and sensitive spectrophotometric method has been proposed for the determinationof vanadium (iv). the method is based on the catalytic effect of v (iv) on the oxidation of alkali blue bypotassium bromate at ph 4. the rate of decrease in the absorbance of alkali blue (at 572 nm) wasproportional to the concentration of v (iv) in the range of 100-6000 ng ml-1. the detection limit wa...
Solid-liquid extraction separation based on a speciation method was studied for selective determination of vanadium (IV) and vanadium (V). Both V (IV) and V (V) cations transform to oxo-acid anion along with pH changes in the solution. The pH values for the transition points are different from each other and the difference was utilized in the separation. In the first step, particulate samples a...
The biological chemistry of vanadium has garnered increased attention due to the recent isolation of vanadium enzymes capable of nitrogenase [l] and bromoperoxidase [2,3] activities. The latter enzymes, isolated from marine algae, contain a mononuclear V(V) active site [4] that does not appear to require redox chemistry in the catalytic mechanism. It is well established that bacteria and algae ...
We investigate proximity effects on hydrogen absorption in ultra-thin vanadium layers through combing light transmission and electron scattering. compare the thermodynamic properties of layers, which are based superlattice structure Cr/V (001) Fe/V (001). find an influence finite-size scaling critical temperatures, can be explained by a variation dead vanadium. In addition to this, also verifie...
A method for treating fuel oil and waste water of power plant is suggested which is including vanadium elimination through contacting with humic acid coated magnetic nano-adsorbent. The nano-adsorbent was modified with humic acid (HA) as a compound having carboxyl, hydroxyl and amin functional groups. HA/Fe3O4 nanoparticles were prepared by a co-precipitation procedure and were character...
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