Rational design of nanostructured, noble metal free, ceria–zirconia catalysts with outstanding low temperature oxygen storage capacity

Abstract

On the basis of detailed previous knowledge about the correlation existing between the Oxygen Storage Capacity (OSC) of ceria-zirconia mixed oxides, the nature of redox pretreatments and the nanostructure of this family of complex materials, it has been possible to design a synthetic strategy allowing one to prepare ceria-zirconia and ceria-yttria-doped zirconia materials, with total ceria contents below 20%, featuring OSC values higher than those observed for catalysts which incorporate supported noble metal particles in their formulation, especially in the very low, 373-473 K, temperature range. These novel, noble-metal free and highly reducible, ceria-zirconia materials allow a much more efficient usage of ceria as a component of oxygen storage formulations, which is nowadays considered one of the key innovation targets in the field of lanthanide oxide based catalysts.

Water splitting reaction on Ce0.15Zr0.85O2 driven by surface heterogeneity

“…Moreover, since nature of the segregated phases and surface characteristics of the material significantly influence the H2 yield, 29 a synergy between the ceria-rich phase and the oxynitride structure in promoting the adsorption and splitting of water is conceivable. We can hypothesize that the formation of compositional/structural heterogeneities at the nanoscale, favor a reorganization of the surface and the nucleation of more active ceria-zirconia redox centers during the cycles, 30,31 and that these processes are boosted in presence of the oxynitride phase.The stability of the material was also investigated over six cycles and only a slight decrease of activity was evidenced starting from the last cycle. XPS analysis of the sample after this cycle ( Figure S6) evidenced that the zirconium oxynitride phase is still present, but an increase of the Zr/Ce ratio to a value of 2.1 was observed, Table 1.…”

“…Moreover, since nature of the segregated phases and surface characteristics of the material significantly influence the H2 yield, 29 a synergy between the ceria-rich phase and the oxynitride structure in promoting the adsorption and splitting of water is conceivable. We can hypothesize that the formation of compositional/structural heterogeneities at the nanoscale, favor a reorganization of the surface and the nucleation of more active ceria-zirconia redox centers during the cycles, 30,31 and that these processes are boosted in presence of the oxynitride phase.…”

Performance of a Direct Methane Solid Oxide Fuel Cell Using Nickel-Ceria-Yttria Stabilized Zirconia as the Anode

“…It has been widely reported that the incorporation of Zr 4+ in the lattice of CeO 2 enhances its reducibility and oxygen storage capacity as well as the thermal stability and electrical conductivity of its fluorite structure [17]. The structural and redox properties of ceria-zirconia mixed oxides depend on their composition, and they are markedly influenced by the synthesis procedure and the redox and/or thermal treatments performed.In a previous publication, we reported that the deposition of ceria on the surface of zirconia and yttria-doped zirconia nanocrystals benefits the structural and chemical interactions that can occur between these components using specific high temperature redox ageing treatments [18]. These materials exceed the performance of noble metal loaded catalysts based on bulk ceria-zirconia mixed oxides in terms of reducibility and oxygen exchange capacity.…”

Ultra-simple synthetic approach to the fabrication of CeO2–ZrO2 mixed nanoparticles into homogeneous, domain, and core–shell structures in mesoporous spherical morphologies using supercritical alcohols

“…Well-defined porous nanostructures are also essential for practical applications including high-throughput catalysis [21], high performance lapping and polishing [7], and excellent ion conduction [22]. Previously, we have reported a simple, rapid, one-pot, single-step, and template-free synthesis of mesoporous TiO 2 NPs called micro/mesoporously architected roundly integrated metal oxides (MARIMOs), referencing their similarity in shape to marimo (Cladophora aegagropila) moss balls (Fig.…”

“…However, decreasing the required amount of the rare earth metal Ce without losing the performance of the material has become a crucial aspect of current research because of resource limitations [6][7][8]. As a practical approach for minimizing Ce loading on nanomaterials, CeO 2 -ZrO 2 nanocomposites can be used as a substitute because of their chemical, mechanical, and thermal stability.…”