Divergent influence of {1 1 1} vs. {1 0 0} crystal planes and Yb³⁺ dopant on CO oxidation paths in mixed nano-sized oxide Au/Ce_1−xYb_xO_2−x/2 (x = 0 or 0.1) systems

Abstract

In this paper, the fundamental information on interactions in systems concerning nanocrystalline gold disperses on shapely (octahedron-like or cube-like) Ce1-xYbxO2-x/2 (x = 0 or 0.1) support has been discussed. Four...

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

“…High-resolution HAADF-STEM images of the Au/CeO 2 (111) catalyst revealed a preferential orientation of Au crystallites relative to the CeO 2 lattice, with [111] Au parallel to the [111] plane of CeO 2 ( Figure 3 ). This observation agrees well with the data published by our group 45 and other authors. 74 , 75 Moreover, Au NPs are rotated relatively to the CeO 2 support by ∼60° (cf.…”

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

“…In our previous paper, 30 a thorough analysis of the H 2 -TPR results obtained for hierarchical, tube-like CeO 2 and Ce 0.9 Yb 0.1 O 1.95 was carried out. Similar to Au-decorated cube-like and octahedron-like ceria-based oxides, 90 the strong shift has been noted for the low temperature peaks of H 2 uptake (surface reduction peaks) for the decorated samples. As noted, two ranges can be distinguished on all H 2 -TPR curves: low-temperature (−50-200 °C) and high-temperature (200-900 °C) regions.…”

“…As noted, two ranges can be distinguished on all H 2 -TPR curves: low-temperature (−50-200 °C) and high-temperature (200-900 °C) regions. According to the literature, 90,96,97 the bands observed in the low-temperature region are responsible for surface reduction and the ones from the high temperature region for bulk reduction of Ce-ions. It was found that the presence of the Ln 3+ dopant in the ceria matrix causes a shift of the high-temperature band to slightly lower temperatures, which is in good agreement with the literature 98,99 and our previous data.…”

“…It could be due to better anchoring of gold nanoparticles on defective fluorite type structures (F#-type, Ce 0.9 Ln 0.1 O 1.95 ) than on CeO 2 . 86,90 Additionally, one may expect that the presence of oxygen vacancies in the Ln 3+doped Au/Ce 0.9 Ln 0.1 O 1.95 hierarchical systems will be responsible for the increased catalytic activity in relation to Au/CeO 2 . 53,93,94 At this point, it is appropriate to ask the question about the influence of the size of the doping ion (and therefore the type of lattice deformation) on the catalytic activity of Au/Ce 0.9 Ln 0.1 O 1.95 systems.…”

“…As in our previous research into decorated systems, 90 before the reducibility and catalytic tests, all the Au/Ce 0.9 Ln 0.1 O 1.95 samples were pre-treated at 300 °C in static air for 3 h. The activation of the investigated materials by the heat treatment at 300 °C was aimed at the oxygenation of the support (Ce IV 45 and generation of the Au δ+ species in the gold nanoparticles. 95 As shown in the literature, the increase of the value of the lattice oxygen and the presence of a certain amount of the Au δ+ species increase the catalytic activity of the Au/Ce 0.9 Ln 0.1 O 1.95 systems.…”