نتایج جستجو برای: ceria

تعداد نتایج: 2141  

2014
Paolo Miceli Samir Bensaid Nunzio Russo Debora Fino

AS MORPHOLOGY PLAYS A RELEVANT ROLE IN SOLID/SOLID CATALYSIS, WHERE THE NUMBER OF CONTACT POINTS IS A CRITICAL FEATURE IN THIS KIND OF REACTION, THREE DIFFERENT CERIA MORPHOLOGIES HAVE BEEN INVESTIGATED IN THIS WORK AS SOOT OXIDATION CATALYSTS: ceria nanofibers, which can become organized as a catalytic network inside diesel particulate filter channels and thus trap soot particles at several co...

2000
Yue Li Qi Fu Maria Flytzani-Stephanopoulos

In this paper we report on the activity of Cuand Ni-containing cerium oxide catalysts for low-temperature water-gas shift (WGS). Bulk catalysts were prepared in nanocrystalline form by the urea co-precipitation–gelation method. Lanthanum dopant (10 at.%) was used as a structural stabilizer of ceria, while the content of Cu or Ni was in the range of 5–15 at.% (2–8 wt.%). At low metal loadings, C...

2016
Nader Shehata Effat Samir Soha Gaballah Aya Hamed Asmaa Elrasheedy

This work presents a new nanocomposite of cerium oxide (ceria) nanoparticles embedded in electrospun PVA nanofibers for optical sensing of radicals in solutions. Our ceria nanoparticles are synthesized to have O-vacancies which are the receptors for the radicals extracted from peroxide in water solution. Ceria nanoparticles are embedded insitu in PVA solution and then formed as nanofibers using...

2016
Nader Shehata Soha Gaballah Effat Samir Aya Hamed Marwa Saad

This paper introduces a new fluorescent nanocomposite of electrospun biodegradable nanofibers embedded with optical nanoparticles. In detail, this work introduces the fluorescence properties of PVA nanofibers generated by the electrospinning technique with embedded cerium oxide (ceria) nanoparticles. Under near-ultra violet excitation, the synthesized nanocomposite generates a visible fluoresce...

Journal: :Physical review letters 2013
Yi Pan Niklas Nilius Hans-Joachim Freund Joachim Paier Christopher Penschke Joachim Sauer

The role of surface and subsurface O vacancies for gold adsorption on crystalline CeO2(111) films has been investigated by scanning tunneling microscopy and density functional theory. Whereas surface vacancies serve as deep traps for the Au atoms, subsurface defects promote the formation of characteristic Au pairs with a mean atom distance of two ceria lattice constants (7.6 Å). Hybrid density ...

2011
Christian Spiel Peter Blaha Yuri Suchorski Karlheinz Schwarz Günther Rupprechter

In this contribution we present ab initio density-functional-theory (DFT) calculations for CeO2 monolayers on the Pt(111) surface. The ceria surface and ceria-metal interface are of great interest because of the oxygen-storage and release capabilities of ceria, which are widely utilized in catalysis. Both the experimentally reported 3 : 4 [(4 × 4)] and 5 : 7 [(1.4 × 1.4)] matching geometries of...

Journal: :Journal of colloid and interface science 2009
Pierre Alphonse Florence Ansart

Catalyst layers (4-20 microm) of rhodium (1 wt%) supported on alumina, titania, and ceria-zirconia (Ce(0.5)Zr(0.5)O(2)) were coated on stainless-steel corrugated sheets by dip-coating in very stable colloidal dispersions of nanoparticles in water. Catalytic performances were studied for low-temperature (< or = 500 degrees C) steam reforming of propane at a steam to carbon ratio equal to 3 and l...

2012
Chirranjeevi Balaji Gopal Axel van de Walle

Nonstoichiometric ceria(CeO2−δ) is a candidate reaction medium to facilitate two step water splitting cycles and generate hydrogen. Improving upon its thermodynamic suitability through doping requires an understanding of its vacancy thermodynamics. Using density functional theory(DFT) calculations and a cluster expansion based Monte Carlo simulations, we have studied the high temperature thermo...

2012
Qinzhong Feng Zhiyong Zhang Yuhui Ma Xiao He Yuliang Zhao Zhifang Chai

The rapid increase in the use of engineered nanoparticles [ENPs] has resulted in an increasing concern over the potential impacts of ENPs on the environmental and human health. ENPs tend to adsorb a large variety of toxic chemicals when they are emitted into the environment, which may enhance the toxicity of ENPs and/or adsorbed chemicals. The study was aimed to investigate the adsorption and d...

Journal: :Physical chemistry chemical physics : PCCP 2009
Norge C Hernández Ricardo Grau-Crespo Nora H de Leeuw Javier Fdez Sanz

We use density functional theory calculations with Hubbard corrections (DFT+U) to investigate electronic aspects of the interaction between ceria surfaces and gold atoms. Our results show that Au adatoms at the (111) surface of ceria can adopt Au(0), Au(+) or Au(-) electronic configurations depending on the adsorption site. The strongest adsorption sites are on top of the surface oxygen and in ...

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