The Sintering of Au Nanoparticles on Flat {100}, {111} and Zigzagged {111}-Nanofacetted Structures of Ceria and Its Influence on Catalytic Activity in CO Oxidation and CO PROX

Abstract

The thermal stability of Au nanoparticles on ceria support of various morphology (nanocubes, nanooctahedra, and {111}-nanofacetted nanocubes) in oxidizing and reducing atmospheres was investigated by electron microscopy. A beneficial effect of the reconstruction of edges of ceria nanocubes into zigzagged {111}-nanofacetted structures on the inhibition of sintering of Au nanoparticles was shown. The influence of different morphology of Au particles on various ceria supports on the reducibility and catalytic activity in CO oxidation, and CO PROX of Au/ceria catalysts was also investigated and discussed. It was shown, that ceria nanocubes with flat {110} terminated edges are more suitable as a support for Au nanoparticles, used to catalyze CO oxidation, than zigzagged {111}- nanofacetted structures. Graphic Abstract

Metal–Support Interaction and Charge Distribution in Ceria-Supported Au Particles Exposed to CO

“…This information might help elucidate the reaction mechanism of low-temperature CO oxidation on Au/CeO 2 catalysts, which is still under debate. 70 The catalytic activity of the powder sample was studied in detail in our previous works, 44 , 71 showing CO oxidation already at room temperature (an example of the light-off plot for it is shown in Figure S2 in the ESI). An investigation of CO oxidation over Au NPs deposited on epitaxial CeO 2 (111) film grown on Ru(0001) is presented in ref ( 72 ) and demonstrates their high activity at room temperature.…”

“…HAADF-STEM images of the Au NPs supported on CeO 2 nanooctahedra are shown in Figures a and b. The ceria support in the powder sample corresponds to crystalline nanooctahedra terminated by {111} facets. , The gold content in the powder Au/CeO 2 (111) samples, estimated by energy-dispersive X-ray spectroscopy (EDX), was ∼1 at. %.…”

“…The powder sampleceria nanooctahedra decorated with Au NPswas synthesized by the wet chemistry method described in detail previously. , Briefly, the support was synthesized by a microwave-assisted hydrothermal method. 0.4370 g of cerium nitrate Ce­(NO 3 ) 3 · 6H 2 O was first dissolved in 35 mL of distilled water.…”

Eu3+ Species as a Luminescent Probe for Fast Monitoring of the Chemical State of Ceria Catalysts

“…However, the temperature range we studied (25−600 °C) covers temperature windows of almost all industrially relevant redox reactions, such as CO and VOC oxidation. [7][8][9]34,35 It should also be mentioned that the functional properties of the catalysts are mainly determined by their surface composition, and the information on the surface concentration of Eu is essential. There are theoretical and experimental works reporting the segregation of dopants at the surface of nanocrystals as the result of relaxation of the structure stress during thermally induced crystallization of nanocrystals.…”

Hierarchical Au/CeO2systems – influence of Ln3+dopants on the catalytic activity in the propane oxidation process

“…90 Our previous research conducted on model Audecorated ceria-based supports with a given morphology (cubes, octahedra) also showed very good redox properties, but the reduction temperatures of Ce 4+ ions were significantly higher. 90 In the literature, [105][106][107][108] the temperature of the low-temperature reduction of cerium ions in Au/CeO 2 systems is noted in the range of 50-200 °C. Literature reports on Au/CeO 2 systems with the DOM3 type structure show that the low-temperature bands on the H 2 -TPR curve are located at temperatures of 80-90 °C.…”