National Repository of Grey Literature 11 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
"Ab initio" studium systémů na bázi CeO2
Fečík, Michal ; Szabová, Lucie (advisor) ; Chvoj, Zdeněk (referee)
Heterogenní katalýza hraje významnou roli pro zvy¹ování efektivity rùzných procesù. Vysokou katalytickou aktivitu vykazují oxidy ceru patøící k tzv. reducibilním oxidùm, je¾ snadno uvolòují èi (zpìtnì) pøijímají atomy kyslíku prostøednictvím procesù redukce a oxidace. Zámìrem pøedlo¾ené práce je vypoèítat pásové struktury a øezy plochami konstantní energie objemových a povrchových systémù oxidu ceru pomocí kvantovì-mechanické "ab initio"metody Teorie hustotního funkcionálu. Numerické simulace jsou provádìny pomocí programového balíèku Quantum ESPRESSO za u¾ití metod rovinných vln a pseudopotenciálu. Silná korelace elektronù v pøípadì atomù ceru je modelována pøidáním Hubbardova U-èlenu. Hlavní dùraz je kladen na mo¾nost porovnávání teoretických výsledkù s tìmi získanými pomocí experimentální metody úhlovì-rozli¹ené fotoelektronové spektroskopie umo¾òující pøímý zisk jak pásových struktur, tak øezù plochami konstantní energie zkoumaného materiálu. Porovnání pomù¾e jak poznat mo¾nosti a mo¾né hranice zmínìné experimentální metody, tak i roz¹íøit její teoretické zázemí vedoucí k prohloubení znalostí materiálù perspektivních pro katalýzu. Klíèová slova: Teorie hustotního funkcionálu, Hubbardùv U-èlen, pásová struktura, plocha konstantní energie, Brillouinova zóna 1
"Ab initio" study of Cu-Ce-O interface
Szabová, Lucie ; Matolín, Vladimír (advisor) ; Chvoj, Zdeněk (referee)
"Ab initio" study of interface Cu-Ce-O Abstract: The present work is a theoretical analysis based on the numerical DFT+U simulations investigating the structural and electronic properties of Cu/CeO2 model systems, which have important applications as heterogeneous catalysts for environment protection and energy sources. We provide a detailed insight into the cohesion of the interface between metal Cu nanoparticles supported on CeO2 substrates. This issue is analyzed both in context of small supported Cu clusters as well as for the extended interface underneath Cu nanoparticles on ceria surfaces. These cases were modelled with a Cu(111)/CeO2(111) interface and with a Cu adatom adsorbed at the oxidized and reduced CeO2(111) surface, respectively. The thesis provides a direct correlation between the cohesive and electronic properties mediated by the charge transfer process. The reduction of surface cerium atoms in the presence of copper either in form of adatom, thin copper layer or a slab of copper is predicted to result from charge transferred from the metal. Since cerium reduction is suggested to play an important role into the catalytic activity of ceria-based catalysts, by predicting the reduction of cerium ions in the presence of copper it can be expected that Cu/CeO2 systems will have important...
"Ab initio" study of Cu-Ce-O interface
Szabová, Lucie ; Matolín, Vladimír (advisor) ; Chvoj, Zdeněk (referee)
"Ab initio" study of interface Cu-Ce-O Abstract: The present work is a theoretical analysis based on the numerical DFT+U simulations investigating the structural and electronic properties of Cu/CeO2 model systems, which have important applications as heterogeneous catalysts for environment protection and energy sources. We provide a detailed insight into the cohesion of the interface between metal Cu nanoparticles supported on CeO2 substrates. This issue is analyzed both in context of small supported Cu clusters as well as for the extended interface underneath Cu nanoparticles on ceria surfaces. These cases were modelled with a Cu(111)/CeO2(111) interface and with a Cu adatom adsorbed at the oxidized and reduced CeO2(111) surface, respectively. The thesis provides a direct correlation between the cohesive and electronic properties mediated by the charge transfer process. The reduction of surface cerium atoms in the presence of copper either in form of adatom, thin copper layer or a slab of copper is predicted to result from charge transferred from the metal. Since cerium reduction is suggested to play an important role into the catalytic activity of ceria-based catalysts, by predicting the reduction of cerium ions in the presence of copper it can be expected that Cu/CeO2 systems will have important...
"Ab initio" studium systémů na bázi CeO2
Fečík, Michal ; Szabová, Lucie (advisor) ; Chvoj, Zdeněk (referee)
Heterogenní katalýza hraje významnou roli pro zvy¹ování efektivity rùzných procesù. Vysokou katalytickou aktivitu vykazují oxidy ceru patøící k tzv. reducibilním oxidùm, je¾ snadno uvolòují èi (zpìtnì) pøijímají atomy kyslíku prostøednictvím procesù redukce a oxidace. Zámìrem pøedlo¾ené práce je vypoèítat pásové struktury a øezy plochami konstantní energie objemových a povrchových systémù oxidu ceru pomocí kvantovì-mechanické "ab initio"metody Teorie hustotního funkcionálu. Numerické simulace jsou provádìny pomocí programového balíèku Quantum ESPRESSO za u¾ití metod rovinných vln a pseudopotenciálu. Silná korelace elektronù v pøípadì atomù ceru je modelována pøidáním Hubbardova U-èlenu. Hlavní dùraz je kladen na mo¾nost porovnávání teoretických výsledkù s tìmi získanými pomocí experimentální metody úhlovì-rozli¹ené fotoelektronové spektroskopie umo¾òující pøímý zisk jak pásových struktur, tak øezù plochami konstantní energie zkoumaného materiálu. Porovnání pomù¾e jak poznat mo¾nosti a mo¾né hranice zmínìné experimentální metody, tak i roz¹íøit její teoretické zázemí vedoucí k prohloubení znalostí materiálù perspektivních pro katalýzu. Klíèová slova: Teorie hustotního funkcionálu, Hubbardùv U-èlen, pásová struktura, plocha konstantní energie, Brillouinova zóna 1
Chemical reactivity of metal-supported ceria thin films: a density functional study
Szabová, Lucie ; Matolín, Vladimír (advisor) ; Balducci, Gabriele (referee) ; Chvoj, Zdeněk (referee)
Title: Chemical reactivity of metal-supported ceria thin films: a density func- tional study Author: Lucie Szabová Department: Department of Surface and Plasma Science Supervisor: Prof. RNDr. Vladimír Matolín, DrSc., Department of Surface and Plasma Science, FMF, CU Abstract: The present work is a theoretical analysis based on numerical DFT+U simulations investigating the physical and chemical properties of ultrathin ceria films supported by Cu(111). Such materials exhibit high activity towards several important reactions in heterogeneous catalysis such as water-gas shift and CO oxidation, with important applications also for renewable energy technologies such as fuel cells. We provide evidence of the influence of film thickness on the electronic and structural properties as well as on the reactivity of ultrathin ceria films supported by copper. The calculations combined with scanning tunneling microscopy experiments show that one monolayer thin film of ceria on Cu(111) is charged, strained and contains oxygen vacancies due to the limited thickness of the film. The influence of the film thickness on the reactivity of thin ceria films was explored for the case of water adsorption and dissociation. Significant differences were shown for water adsorption and dissociation on one-monolayer ceria compared to thicker films,...
"Ab initio" study of Sn-Ce-O mixed oxides
Fečík, Michal ; Szabová, Lucie (advisor) ; Mazur, Daniel (referee)
The present work is focused on a theoretical analysis based on the numerical DFT+U calcula- tions investigating structural and electronic properties of mixed oxide Sn/CeO2. The main reasons for this study are reported improved catalytic properties of this system that are most probably caused by catalytic properties of cerium oxides, which are based on releasing or (re)capturing of oxygen atoms via the process of cerium oxidation and reduction. In this work we study com- pounds of cerium and tin that compose Sn/CeO2 - that is a metal Sn and CeO2 together with other compounds SnO2 and Ce2O3 - especially by means of band structures and densities of states. Furthermore we studied mixed oxide Sn/CeO2 in terms of electronic structure and morphology. In this work we consider two different modifications of the analyzed system - the first one con- tains oxygen vacancy whereas the second one stay unchanged. Our study is focused on analysis of influence of tin defect upon properties of CeO2, mainly its effect on reduction of cerium atoms. 1
Theoretical calculation of stability and electronic structure of Si surfaces
Krejčí, Ondřej ; Kocán, Pavel (advisor) ; Szabová, Lucie (referee)
ÁÒ Ø × ÛÓÖ Á Ö Ý ×ÙÑÑ Ö Þ ¹ Ò Ø Ó Ñ Ø Ó × ÓÖ ÓÑÔÙØ Ø ÓÒ Ò ØÓÑ Ò Ò Ð ØÖÓÒ ×ØÖÙ ØÙÖ Ó ÑÓÐ ÙР׸ ×ÓÐ ×Ø Ø × Ò Ø Ö ×ÙÖ × Ô ÖØ ¹ ÙÐ ÖÐÝ Á ÔÙÖ×Ù Ò× ØÝ ÙÒ Ø ÓÒ Ð Ø ÓÖÝž Ì Ò Á × Ö Ø Ñ Ø Ó Ó Ö ÐÐ × ÑÙÐ Ø ÓÒ Ô Ö ¸ Û × × ÓÒ Ø Ò× ØÝ ÙÒ Ø ÓÒ Ð Ø ÓÖÝž Ï Ø Ö ÐÐ Á Ñ ÓÑÔÙØ Ø ÓÒ× Ó Ø Ð ØÖÓÒ ×ØÖÙ ØÙÖ Ó Ë Ð ÓÒ ÙÐ Ò ÓÑÔÙØ Ø ÓÒ× Ó Ø ØÓÑ Ò Ø Ð ØÖÓÒ ×ØÖÙ ØÙÖ Ó Ö ÓÒ×ØÖÙ Ø ÓÒ× 2×1¸ Ô'2×2µ Ò '4×4µ Ó Ë '½¼¼µ ×ÙÖ ž Á ÓÑÔ Ö ÑÝ Ö ×ÙÐØ× Û Ø ÔÖ ¹ Ú ÓÙ×ÐÝ Ñ Ò ÔÙ Ð × ÓÑÔÙØ Ø ÓÒ× Ò ÜÔ Ö Ñ ÒØ× Ö ž ËÙ × ÕÙ ÒØÐÝ Á Ô Ö ÓÖÑ ËÌÅ × ÑÙÐ Ø ÓÒ× Ó Ø × Ö ÓÒ×ØÖÙ Ø ÓÒ׸ Û Á Ð×Ó ÓÑÔ Ö Û Ø Ø ÜÔ Ö Ñ ÒØ Ð Ø ž ½
"Ab initio" study of Cu-Ce-O interface
Szabová, Lucie ; Matolín, Vladimír (advisor) ; Chvoj, Zdeněk (referee)
"Ab initio" study of interface Cu-Ce-O Abstract: The present work is a theoretical analysis based on the numerical DFT+U simulations investigating the structural and electronic properties of Cu/CeO2 model systems, which have important applications as heterogeneous catalysts for environment protection and energy sources. We provide a detailed insight into the cohesion of the interface between metal Cu nanoparticles supported on CeO2 substrates. This issue is analyzed both in context of small supported Cu clusters as well as for the extended interface underneath Cu nanoparticles on ceria surfaces. These cases were modelled with a Cu(111)/CeO2(111) interface and with a Cu adatom adsorbed at the oxidized and reduced CeO2(111) surface, respectively. The thesis provides a direct correlation between the cohesive and electronic properties mediated by the charge transfer process. The reduction of surface cerium atoms in the presence of copper either in form of adatom, thin copper layer or a slab of copper is predicted to result from charge transferred from the metal. Since cerium reduction is suggested to play an important role into the catalytic activity of ceria-based catalysts, by predicting the reduction of cerium ions in the presence of copper it can be expected that Cu/CeO2 systems will have important...

National Repository of Grey Literature : 11 records found   1 - 10next  jump to record:
See also: similar author names
2 Szabová, Lenka
1 Szabová, Leona
2 Szabová, Lucia
Interested in being notified about new results for this query?
Subscribe to the RSS feed.