نتایج جستجو برای: ceria nanoparticle
تعداد نتایج: 32984 فیلتر نتایج به سال:
Fuel cells, and in particular solid-oxide fuel cells (SOFCs), enable high-efficiency conversion of chemical fuels into useful electrical energy and, as such, are expected to play a major role in a sustainable-energy future. A key step in the fuel-cell energy-conversion process is the electro-oxidation of the fuel at the anode. There has been increasing evidence in recent years that the presence...
The partial oxidation of methane to syngas was studied in this work over Ni-containing ceria catalysts with nickel content of 5, 10 and 20 at.% at atmospheric pressure. All catalysts, in the as prepared state, showed similar activity and CO selectivity at T ≥ 550◦C. Catalyst pre-reduction was not required. Reaction mixtures were dilute, containing 3 mol% CH4 and 1.5 mol% O2. Methane conversion ...
in this work, ce0.75gd0.1ca0.15o1.8 nanopowders are successfully synthesized by a glycine-nitrate combustionprocess under the microwave irradiation. then calcination was carried out at 700 °c. calcined powdersidentified by room temperature x-ray diffraction were single phase and had a crystallite size between 16 to 24nm (based on schererr formula). scanning electron microscopy (sem) was employe...
The water–gas shift (WGS) reaction (CO+H2OQCO2+H2) plays an important role in fuel processing for polymer electrolyte membrane (PEM) fuel-cell applications. The hydrogen in the reformate gas is upgraded by removal of the carbon monoxide, which is a strong poison of the anode catalysts in current PEM fuel cells. Active shift catalysts that are also stable under the operating conditions of practi...
The formation of oxygen vacancies in nanoparticles Ce(n)O(2n) (n < or = 80), studied using density-functional calculations, is found to be greatly facilitated compared to extended surfaces, which explains the observed spectacular reactivity of nanostructured ceria.
Abstract Cerium dioxide CeO 2 (ceria) is an important material in catalysis and energy applications. The intrinsic Frenkel Schottky defects can impact a wide range of properties including the oxygen storage capacity, redox cycle, ionic thermal transport. Here, we study on structural dynamics ceria using density functional theory. phonon contributions to free are found reduce defect formation en...
The attention on CeO2-NPs environmental and in vivo effects is due to their presence in diesel exhaust and in diesel filters that release a more water-soluble form of ceria NPs, as well as to their use for medical applications. In this work, acute and subacute in vivo toxicity assays demonstrate no lethal effect of these NPs. Anyhow, performing in vivo evaluations on CD-1 mouse systems, we demo...
Low-temperature scanning tunneling microscopy and spectroscopy have been employed to analyze the local electronic structure of the (111) surface of a ceria thin film grown on Ru(0001). On pristine, defect-free oxide terraces, the empty 4f states of Ce(4+) ions appear as the only spectral feature inside the 6 eV oxide band gap. In contrast, occupied states are detected between -1.0 and -1.5 eV b...
Ceria-supported Pd is a promising heterogeneous catalyst for CO oxidation relevant to environmental cleanup reactions. Pd loaded onto a nanorod form of ceria exposing predominantly (111) facets is already active at 50 °C. Here we report a combination of CO-FTIR spectroscopy and theoretical calculations that allows assigning different forms of Pd on the CeO2(111) surface during reaction conditio...
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