Search results for "cobalt oxide"
showing 10 items of 22 documents
Oxygen evolution reaction on a N-doped Co0.5-terminated Co3O4 (001) surface
2020
The project AP05131211 “First principles investigation on catalytic properties of N-doped Co3O4.” was funded by the Ministry of Education and Science of the Republic of Kazakhstan. The work was partly supported by COST (European Cooperation in science and Technology) Action 18234 (YM and EK). The work of T. Inerbaev was performed under the state assignment of Sobolev Institute of Geology and Mineralogy Siberian Branch of the Russian Academy of Sciences. YM and EK thank Sun-to-Chem project of ERA Net.
Formation of cobalt silicide from filter metal vacuum arc deposited films
2006
The thermal reaction of Co film deposited on Si(111) surfaces by a high current filter metal vacuum arc (FMEVAD) system has been studied. After deposition the films were annealed over the 400-900 degrees C temperature range for 30 min. Rutherford backscattering spectrometry (RBS) was used to characterize the elemental depth distributions in the films subjected to different annealing temperatures. Ordered chemical phases were determined by glancing-incidence X-ray diffraction (GIXRD) and the morphology was determined by cross section transmission electron microscopy (TEM). The results show that the phases formed are Co2Si at 400 degrees C, CoSi + Coo at 500 degrees C, CoSi + CoSi2 at 600 deg…
Structural and morphological investigation of a cobalt catalyst supported on alumina-baria: effects of redox treatments on the activity in the NO red…
2004
Abstract Temperature-programmed reduction (TPR) and temperature-programmed oxidation (TPO) have been used to study the various cobalt species formed in a cobalt catalyst (Co 1 wt.%) supported on alumina-baria, with composition Al2O3(80 wt.%)–BaO (20 wt.%). The catalyst was synthesized by incipient-wetness impregnation of the support with a water solution of cobalt acetylacetonate and calcined at 550 °C for 5 h. In order to investigate the structure and morphology of the sample, XRD, BET and SEM analyses were performed. Depending on the temperature and nature of pre-treatment (reductive or oxidative) different Co species (Co3O4, Co3+, surface Co2+, CoAl2O4) were formed. Activity tests in the…
Co3O4/CeO2 composite oxides for methane emissions abatement: Relationship between Co3O4–CeO2 interaction and catalytic activity
2006
Abstract Co 3 O 4 /CeO 2 composite oxides with different cobalt loading (5, 15, 30, 50, 70 wt.% as Co 3 O 4 ) were prepared by co-precipitation method and investigated for the oxidation of methane under stoichiometric conditions. Pure oxides, Co 3 O 4 and CeO 2 were used as reference. Characterization studies by X-ray diffraction (XRD), BET, temperature programmed reduction/oxidation (TPR/TPO) and X-ray photoelectron spectroscopy (XPS) were carried out. An improvement of the catalytic activity and thermal stability of the composite oxides was observed with respect to pure Co 3 O 4 in correspondence of Co 3 O 4 –CeO 2 containing 30% by weight of Co 3 O 4 . The combined effect of cobalt oxide…
Ibuprofen degradation using a Co-doped carbon matrix derived from peat as a peroxymonosulphate activator
2021
The wider presence of pharmaceuticals and personal care products in nature is a major cause for concern in society. Among pharmaceuticals, the anti-inflammatory drug ibuprofen has commonly been found in aquatic and soil environments. We produced a Co-doped carbon matrix (Co-P 850) through the carbonization of Co2+ saturated peat and used it as a peroxymonosulphate activator to aid ibuprofen degradation. The properties of Co-P 850 were analysed using field emission scanning electron microscopy, energy filtered transmission electron microscopy and X-ray photoelectron spectroscopy. The characterization results showed that Co/Fe oxides were generated and tightly embedded into the carbon matrix …
Soluble Complexes of Cobalt Oxide Fragments Bring the Unique CO2 Photoreduction Activity of a Bulk Material into the Flexible Domain of Molecular Sci…
2021
The deposition of metal oxides is essential to the fabrication of numerous multicomponent solid-state devices and catalysts. However, the reproducible formation of homogeneous metal oxide films or of nanoparticle dispersions at solid interfaces remains an ongoing challenge. Here we report that molecular hexaniobate cluster anion complexes of structurally and electronically distinct fragments of cubic-spinel and monoclinic Co3O4 can serve as tractable yet well-defined functional analogues of bulk cobalt oxide. Notably, the energies of the highest-occupied and lowest-unoccupied molecular orbitals (HOMO and LUMO) of the molecular complexes, 1, closely match the valence- and conduction-band (VB…
The different catalytic behaviour in the propane total oxidation of cobalt and manganese oxides prepared by a wet combustion procedure
2013
Abstract Cobalt oxide and manganese oxide catalysts have been prepared through aqueous synthesis using a wet combustion procedure. These materials have been tested as catalysts for the total oxidation of propane. It has been observed a different catalytic behaviour between cobalt and manganese oxides although for both oxides a very high catalytic activity has been obtained. Cobalt oxides prepared by the wet combustion procedure are less reactive than a simple cobalt oxide prepared without the addition of organic acids. However, in the case of manganese oxide the use of organic acids highly increases the catalytic activity. The different catalytic behaviour has been related to the variation …
TAP reactor study of the deep oxidation of propane using cobalt oxide and gold-containing cobalt oxide catalysts
2009
Abstract A transient reactor study of the oxidation of propane to CO 2 on gold-free and gold-doped CoO x catalysts has been carried out. It has been demonstrated that the presence of gold markedly promotes the catalytic reactivity of cobalt oxide in the total oxidation of propane. Both catalysts oxidised propane directly to CO 2 via a Mars–Van Krevelen mechanism, and this was confirmed using isotopically labelled oxygen experiments. The increased activity of the gold catalyst is related to the faster reoxidation of the cobalt oxide when gold is present in the catalyst, since the reaction step in which the catalyst is reduced, due to propane oxidation, is similar for both catalysts. The fast…
Trivalent cation substitution of pulverulent cobalt—iron molybdates Co1 − xFexMoO4
1998
Abstract Different mixed cobalt—iron molybdates Co1 − xFexMoO4 (0 ≤ x ≤ 1) have been prepared by means of a ceramic process. The oxidation of pulverulent samples leads to ferric molybdate Fe2(MoO4)3, spinelle Co3O4 and cobalt molybdate CoMoO4. After a strong grinding which reduces the grain size (about 0.1 μm) and induces crystallographic defects in the grains, the cobalt—iron molybdates can be partially oxidized into cation-deficient phases. This oxidation corresponds to an isostructural substitution of part of the Fe2+ and Co2+ ions by Fe3+ and Co3+ ions and the creation of cation vacancies. The concomitant presence of trivalent cations and associated cation vacancies in the lattice stabi…
Total oxidation of propane using nanocrystalline cobalt oxide and supported cobalt oxide catalysts
2008
Abstract Supported and unsupported nanocrystalline cobalt oxides have been shown to be extremely efficient catalysts for the total oxidation of propane. Total conversion with a high stability has been achieved at reaction temperatures as low as 250 °C. In the present work, a comparison between the catalytic performance of bulk and alumina-supported nanocrystalline cobalt oxide catalysts has been made. The influence of crystallite size, nature of the support (alpha, gamma and mesoporous alumina) and cobalt loading, has been probed. Unsupported cobalt oxide catalysts were more active than any supported cobalt oxide catalysts. The catalytic activity was mainly dependent on the crystallite size…