نتایج جستجو برای: Doped ceria
تعداد نتایج: 49755 فیلتر نتایج به سال:
Being endowed with an ability of capturing and releasing oxygen, the ceria surface conventionally assumes the role of catalyzing redox reactions in chemistry. This catalytic effect also makes possible its cytotoxicity toward microorganisms at room temperature. To study this cytotoxicity, we synthesized the doped and undoped ceria particles of 8-9 nm in size using an inexpensive precipitation me...
Nickel/doped-ceria composites are promising electrocatalysts for solid-oxide fuel and electrolysis cells. Very often steam is present in the feedstock of the cells, frequently mixed with other gases, such as hydrogen or CO2 . An increase in the steam concentration in the feed mixture is considered accountable for the electrode oxidation and the deactivation of the device. However, direct experi...
Model-type thin films of Gd doped and Gd/Mn co-doped ceria were investigated by means of impedance spectroscopy in a humid H2 atmosphere. A novel measurement technique for microelectrodes with interdigitating Pt current collectors was employed. This method allows a separation of the different elementary processes contributing to the electrode impedance. After annealing at 650°C in humid H2 atmo...
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 thermodynamic properties of surface ceria were investigated through equilibrium isotherms determined by flow-titration and coulometric-titration measurements on high-surface-area ceria and ceria supported on La-modified alumina (LA). While the surface area of pure ceria was found to be unstable under redox conditions, the extent of reduction at 873 K and a P(O2) of 1.6x10-26 atm increased w...
In recent years, ceria and doped-ceria anisotropic nanocrystals (NC’s) have been produced by a variety of solution-based synthetic routes. The motivation in producing ceria-based NCs with controlled morphology is to develop high surface area catalyst supports with well-defined exposed crystal planes that exhibit optimal catalytic activity. Understanding the growth mechanism of CeO2 NC’s is vita...
Doped ceria is considered as an electrolyte for solid oxide fuel cell applications. The introduction of dopants in the ceria lattice will affect its electronic structure and, in turn, its ionic conductivity. Simulation of these issues using density functional theory becomes complicated by the random distribution of the constituent atoms. Here we use the generalized gradient approximation with o...
This Perspective covers sustainable oxidation processes using doped cerias, ceria-supported catalysts and ceria-based mixed oxides. Firstly, we consider the general properties of ceria-based catalysts. We outline the advantages of the ceria redox cycle, and explain the dynamic behaviour of these catalysts in the presence of metal additives and dopants. We then review three types of catalytic ox...
The nano-domain, with short-range ordered structure, has been widely observed in rare-earth-doped ceria. Atomistic simulation has been employed to investigate the ordering structure of the nano-domain, as a result of aggregation and segregation of dopant cations and the associated oxygen vacancies in gadolinium-doped ceria. It is found that the binding energy of defect cluster increases as a fu...
Thermochemical splitting of CO2 via a ceria-based redox cycle was performed in a solar-driven thermogravimetric analyzer. Overall reaction rates, including heat and mass transport, were determined under concentrated irradiation mimicking realistic operation of solar reactors. Reticulated porous ceramic (RPC) structures and fibers made of undoped and Zr4+-doped CeO2, were endothermally reduced u...
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