نتایج جستجو برای: vanadium v
تعداد نتایج: 309447 فیلتر نتایج به سال:
The dispersive part of the refractive index of vanadium is determined by measuring the angular displacement of the first order diffraction peak of a V/Fe superlattice. The measurements were made using elliptically polarized synchrotron radiation which was scanned through the V L2,3 absorption edges for different incident scattering angles. The x-ray scattering technique provides access to direc...
In this paper, the composite additive of CaF2/CaO was used to extract vanadium from stone coal, and the effect of roasting and leaching kinetics were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using the composite additive. The experimental results indicated that the roasted clinker can be obtained under the conditions of CaF2/CaO at a...
Neutral vanadium sulfide clusters are generated by the reaction of seeded hydrogen sulfide in a helium carrier gas with laser ablated vanadium metal within a supersonic nozzle. The exiting clusters are expanded into a vacuum in a molecular beam and are ionized by both ultraviolet (UV) and vacuum UV (VUV) laser radiation. The generated ions are detected by a time of flight mass spectrometer. Wit...
The application of analytical transmission electron microscopy in characterisations of catalytic materials is presented by studying the mechanically activated vanadium pentoxide V2O5. Local morphology and lattice distortion are studied by TEM while the oxidation states are determined by EELS. The mechanical activation can be described as a two -stage process: crushing of large crystals into sma...
the electrocatalysis of the oxygen reduction reaction (orr) on carbon supportedpt-v (1:1) catalyst in polymer electrolyte fuel cells (pefc) was investigated. atan oxygen pressure of one atm an enhanced electrocatalytic property of pt-v/ccompared with pt/c is revealed. these results indicate the occurrence of adifferent electrocatalytic mechanism for the orr on pt/c and pt-v/c. anincrease of mas...
A simple and versatile method for preparation of new crystalline vanadium oxide hydrate semi-microspheres is developed via a simple hydrothermal route, which are tested as a novel high-energy anode materials for sodium-ion batteries. The enhancement of electrochemical performance for the vanadium oxide hydrate electrode is offered by addition of graphene. The graphene-based vanadium oxide hydra...
Soft landing (SL) of mass-selected ions is used to transfer catalytically-active metal complexes complete with organic ligands from the gas phase onto an inert surface. This is part of an effort to prepare materials with defined active sites and thus achieve molecular design of surfaces in a highly controlled way. Solution-phase electrochemical studies have shown that V(IV)O(salen) reacts in th...
The stability constant of the complex vanadium(v) p-chloro-N-Phenyl-p-chlorobenzohydroxamic acid was determined spectrophotometrically. The ligand p-chloro-N-phenyl-p-chloro-benzohydroxamic acid abbreviated in this paper as PCNPPCBHA was synthesized by the coupling of equimolar solutions of p-chlorobenzoyl chloride and freshly prepared p-chloro-ß-phenyl hydroxylamine; in which the later was pre...
The oxidation of methanol to formaldehyde on silica supported vanadium oxide is studied by density functional theory. For isolated vanadium oxide species silsesquioxane-type models are adopted. The first step is dissociative adsorption of methanol yielding CH3O(O=)V(O-)2 surface complexes. This makes the O=V(OCH3)3 molecule a suited model system. The rate-limiting oxidation step involves hydrog...
The vibrational spectra of vanadium oxide anions ranging from V(2)O(6)(-) to V(8)O(20)(-) are studied in the region from 555 to 1670 cm(-1) by infrared multiple photon photodissociation (IRMPD) spectroscopy. The cluster structures are assigned and structural trends identified by comparison of the experimental IRMPD spectra with simulated linear IR absorption spectra derived from density functio...
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