Relationship between Structure and CO Oxidation Activity of Ceria-Supported Gold Catalysts

Venezia, Anna Maria; Pantaleo, G.; Longo, Alessandro; Carlo, Gabriella Di; Casaletto, Maria Pia; Liotta, Leonarda Francesca; Deganello, G.

doi:10.1021/jp045928i

Cited by 275 publications

(193 citation statements)

References 48 publications

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“…/Ce 4? by Au 3? [20,[37][38][39][40]. Recently, EXAFS structure analysis showed that the isolated Au cations in leached Au/CeO 2 are surrounded by oxygen and cerium, respectively, in the first and second coordination shell in agreement with Au substitution for Ce [11].…”

Section: Introductionmentioning

confidence: 91%

“…In line with the importance of the interactions between gold and the support, it has been found that nanoscale forms of ceria contribute to the high activity of small gold particles [18][19][20][21][22][23][24]. Several authors [25][26][27][28] have used nanostructured ceria that expose certain planes to investigate the influence of the nature of the ceria surface on the nature and activity of gold species.…”

Section: Introductionmentioning

confidence: 99%

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Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

et al. 2011

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The interaction of gold atoms with CeO 2 nanocrystals having rod and cube shapes has been examined by cyanide leaching, TEM, TPR, CO IR and X-ray absorption spectroscopy. After deposition-precipitation and calcination of gold, these surfaces contain gold nanoparticles in the range 2-6 nm. For the ceria nanorods, a substantial amount of gold is present as cations that replace Ce ions in the surface as follows from their first and second coordination shells of oxygen and cerium by EXAFS analysis. These cations are stable against cyanide leaching in contrast to gold nanoparticles. Upon reduction the isolated Au atoms form finely dispersed metal clusters with a high activity in CO oxidation, the WGS reaction and 1,3-butadiene hydrogenation. By analogy with the very low activity of reduced gold nanoparticles on ceria nanocubes exposing the {100} surface plane, it is inferred that the gold nanoparticles on the ceria nanorod surface also have a low activity in such reactions. Although the finely dispersed Au clusters are thermally stable up to quite high temperature in line with earlier findings (Y. Guan and E. J. M. Hensen, Phys Chem Chem Phys 11:9578, 2009), the presence of gold nanoparticles results in their more facile agglomeration, especially in the presence of water (e.g., WGS conditions). For liquid phase alcohol oxidation, metallic gold nanoparticles are the active sites. In the absence of a base, the O-H bond cleavage appears to be rate limiting, while this shifts to C-H bond activation after addition of NaOH. In the latter case, the gold nanoparticles on the surface of ceria nanocubes are much more active than those on the surface of nanorod ceria.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

et al. 2011

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“…6 shows the H 2 -TPR profiles of CeO 2 and Ag/CeO 2 nanomaterials. All CeO 2 samples exhibited a broad reduction peak at 400-600°C, which was the hydrogen consumed peak of surface oxygen [18,25]. The more intense low-temperature reduction peaks of the CeO 2 nanorods and nanocubes indicated that a higher amount of hydrogen was consumed, i.e.…”

Section: Characterization and Effects Of Shape Crystalline Phase Andmentioning

confidence: 97%

“…Due to the high oxygen transport and storage capacities of ceria (CeO 2 ), notable surface oxygen species form on CeO 2 nanomaterials [17] widely employed in heterogeneous catalysis [18][19][20]. Ceria is an interesting oxide because oxygen vacancy defects can be rapidly formed, thus O vacancies and ROS in CeO 2 are naturally anticipated in catalytic processes.…”

Section: Introductionmentioning

confidence: 99%

Morphology-dependent bactericidal activities of Ag/CeO2 catalysts against Escherichia coli

Wang

et al. 2014

Journal of Inorganic Biochemistry

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Silver-loaded CeO 2 nanomaterials (Ag/CeO 2 ) including Ag/CeO 2 nanorods, nanocubes, nanoparticles were prepared with hydrothermal and impregnation methods. Catalytic inactivation of Escherichia coli with Ag/CeO 2 catalysts through the formation of reactive oxygen species (ROS) was investigated. For comparison purposes, the bactericidal activities of CeO 2 nanorods, nanocubes and nanoparticles were also studied. There was a 3-4 log order improvement in the inactivation of E. coli with Ag/CeO 2 catalysts compared with CeO 2 catalysts. Temperature-programmed reduction of H 2 showed that Ag/CeO 2 catalysts had higher catalytic oxidation ability than CeO 2 catalysts, which was the reason for that Ag/CeO 2 catalysts exhibited stronger bactericidal activities than CeO 2 catalysts. Further, the bactericidal activities of CeO 2 and Ag/CeO 2 depend on their shapes. Results of 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping measurements by electron spin resonance and addition of catalase as a scavenger indicated the formation of •OH, •O 2 − , and H 2 O 2 , which caused the obvious bactericidal activity of catalysts. The stronger chemical bond between Ag and CeO 2 nanorods led to lower Ag + elution concentrations.The toxicity of Ag + eluted from the catalysts did not play an important role during the bactericidal process. Experimental results also indicated that Ag/CeO 2 induced the production of intracellular ROS and disruption of the cell wall and cell membrane. A possible production mechanism of ROS and bactericidal mechanism of catalytic oxidation were proposed.

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“…As was established, during the reaction in the dry condition the oxidized gold phases (Au 2 O 3 in Au/Fe 2 O 3 , Au(OH) 3 and Au 2 O 3 in Au/Al 2 O 3 ), which coexisted in the as-prepared catalysts along with Au 0 , were reduced almost completely to metallic Au, however after the reaction in the wet condition about 40% of the oxidic gold remained. The gradual reduction of Au III species to metallic gold in an Au/Fe 2 O 3 catalyst was also observed in work [4], whereas in an Au/CeO 2 catalyst the Au III ions were reduced under CO oxidation reaction conditions to Au  species [5]. The data on the chemical and electronic state of gold nanoparticles in different catalysts used in the CO oxidation as determined by the Au 4f binding energy are rather contradictory, although they clearly indicate that formation and modification of the particles' electronic state strongly depend on the nature of support.…”

Section: Introductionmentioning

confidence: 53%

XPS/ToF-SIMS Characterization of TiO$_{2}$ Supported Au Nanoparticles: Effect of Catalytic CO Oxidation

Chenakin¹,

Kruse²,

Vasylyev³

et al. 2016

Metallofiz. Noveishie Tekhnol.

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X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) are employed for a comparative study of the surface composition and electronic structure of an Au/TiO 2 catalyst in the asprepared state and after using it in the reaction of CO oxidation at room temperature. As found, the reaction-induced changes in the morphology of Au nanoparticles related to their agglomeration are accompanied by modification of the electronic state of the catalyst via an enhanced electron transfer to the gold atoms that shows up as an additional negative shift of the Au 4f spectrum and its distortion. The catalytic reaction of CO oxidation results in the loss of hydroxyl groups and accumulation on the support surface of various carbon-containing species with the leading formation of carbonate and bicarbonate groups, which increases with time on stream. The role of these factors in deactivation of the catalyst is discussed.За допомогою рентґенівської фотоелектронної спектроскопії (РФЕС) та часопролітної вторинно-іонної мас-спектрометрії (ЧП-ВІМС) проведено порівняльне дослідження складу поверхні й електронної структури ката-лізатора Au/TiO 2 у свіжоприготованому стані та після його використання у реакції окиснення CO за кімнатної температури. Встановлено, що інду-ковані каталітичною реакцією зміни у морфології наночастинок Au, які спричинені їхньою аґломерацією, супроводжувалися модифікуванням електронного стану каталізатора завдяки посиленому перенесенню елек-тронів на атоми золота, що проявлялося як додатковий неґативний зсув РФЕ-спектра Au 4f і його спотворення. Каталітична реакція окиснення CO призводила до втрати гідроксильних груп та накопичення на поверхні підкладки різних вуглецевмісних функціональних груп з переважним С помощью рентгеновской фотоэлектронной спектроскопии (РФЭС) и времяпролётной вторично-ионной масс-спектрометрии (ВП-ВИМС) про-ведено сравнительное исследование состава поверхности и электронной структуры катализатора Au/TiO 2 в свежеприготовленном состоянии и по-сле его использования в реакции окисления CO при комнатной темпера-туре. Установлено, что индуцированные каталитической реакцией изме-нения в морфологии наночастиц Au, вызванные их агломерацией, сопро-вождались модификацией электронного состояния катализатора путём усиленного переноса электронов на атомы золота, что проявлялось в виде дополнительного отрицательного сдвига РФЭ-спектра Au 4f и его иска-жения. Каталитическая реакция окисления CO приводила к потере гид-роксильных групп и накоплению на поверхности подложки различных углеродсодержащих функциональных групп с преимущественным фор-мированием карбонатов и бикарбонатов, которое усиливалось с течением времени реакции. Обсуждается роль этих факторов в деактивации ката-лизатора.

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Relationship between Structure and CO Oxidation Activity of Ceria-Supported Gold Catalysts

Cited by 275 publications

References 48 publications

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

Morphology-dependent bactericidal activities of Ag/CeO2 catalysts against Escherichia coli

XPS/ToF-SIMS Characterization of TiO$_{2}$ Supported Au Nanoparticles: Effect of Catalytic CO Oxidation

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