A First-Principles Modeling of Ni Interactions on CeO₂−ZrO₂Mixed Oxide Solid Solutions

Abstract

We performed DFT+U quantum period calculations to study the characteristics of Ni interactions on/in CeO2−ZrO2 mixed oxide solid solutions. We analyzed the energetics of Ni adsorption and insertion on/in different surface and subsurface sites of the Ce0.25Zr0.75O2(111) slab, and also the changes in its atomic and electronic structures. The most stable interaction corresponds to a single Ni atom adsorbed on the O−O bridge site, where the nearest-neighbor metal atom is the Zr. Our calculations also show that Ni can form small clusters on the Ce0.75Zr0.25O2(111) surface; which also locate around the Zr dopant. Due to Ni interactions, surface and inner layers oxygen anions experience important modifications in their geometric positions and the Ni atom deposition results in the partial occupation of 7-coordinated Ce(4f) states.

Ce0.80M0.12Sn0.08O2−δ (M = Hf, Zr, Pr, and La) ternary oxide solid solutions with superior properties for CO oxidation

“…One effective strategy to tackle these problems is to form ceria-based binary oxide solid solutions by doping with various transition, rare-earth or alkaline-earth elements. 2,4 It was 40 shown that incorporation of these metals into the CeO 2 lattice enhances its redox properties, OSC, and thermal stability. 2 For example, doping of CeO 2 with Zr resulted in the formation of a ceria-zirconia (CZ) solid solution that promoted its Ce 4+ /Ce 3+ redox couple, leading to an enhanced OSC, thermal resistance, in the literature on the preparation of SnO 2 modified CeO 2 -based binary oxide solid solutions as better ternary oxide catalysts.…”

“…25 The optimized Ce 0.80 Hf 0.12 Sn 0.08 O 2-δ (CHS), Ce 0.80 Zr 0.12 Sn 0.08 O 2-δ (CZS), Ce 0.80 Pr 0.12 Sn 0.08 O 2-δ (CPS), and Ce 0.80 La 0.12 Sn 0.08 O 2-δ (CLS) (mol ratio based on oxides) ternary oxide solid solutions were synthesized by a coprecipitation method. In detail, the desired quantities (see Table S1, ESI †) of Ce(NO 3 ) 3 ·6H 2 O, 30 SnCl 4 ·5H 2 O, and other respective metal precursors such as HfCl 4 , ZrO(NO 3 ) 2 ·xH 2 O, Pr(NO 3 ) 3 ·6H 2 O, and La(NO 3 ) 3 ·6H 2 O were dissolved in distilled water separately and then mixed together for 1 h. Under constant stirring, aqueous ammonia solution was added dropwise to the mixture until the precipitation was 35 complete, at which point the pH was approximately 9.0. The resulting suspensions were stirred for another 12 h, aged for 24 h and then vacuum filtered.…”

Oxygen vacancy formation on the Ni/Ce0.75Zr0.25O2(111) surface. A DFT+U study

“…In a previous work we have found that the most stable Ni interactions on the Ce 0.75 Zr 0.25 O 2 (111) surface corresponds to its deposition over OeO bridge sites [24]. These preferential Ni adsorption sites, named "W" and "X", are shown in Fig.…”

“…Results and discussion [24]. For that purpose, we employed a superlattice consisting on 12 layers of Ce, Zr y O atoms and a vacuum space of approximately 13 Å .…”

Role of the Interface in Base‐Metal Ceria‐Based Catalysts for Hydrogen Purification and Production Processes

“…The interaction of copper with CeZr has been analyzed by TEM and spectroscopic methods showing that the base metal is able to interact strongly with the oxide surfaces and thus to facilitate its stability under the reaction conditions . For nickel, theoretical studies indicate that Zr favors the interaction of the base metal with the fluorite structure, the stabilization of the full oxidation state, as well as the production of oxygen vacancies . In general, the above‐mentioned contributions indicated an improved ceria redox performance as responsible for the enhancement of catalytic activity.…”