Binary Neutral Metal Oxide Clusters with Oxygen Radical Centers for Catalytic Oxidation Reactions: From Cluster Models Toward Surfaces

Abstract

We present theoretical results based on DFT calculations of the reactivity of binary neutral stoichiometric Zr n-1 ScO 2n clusters with oxygen radical centers toward CO and acetylene with the aim to build a bridge between clusters and surface models. Following the concept of the same total valence electron count, the studied series of binary clusters mimics cationic stoichiometric (ZrO 2 ) n + species characterized also by the presence of an oxygen radical center. In the case of Zr 11 ScO 24 , representing a section of the (ZrO 2 ) n bulk, in addition to the oxygen radical center, the presence of neighboring Zr atoms effectively promotes oxidation reactions toward CO and acetylene, showing the importance of the surrounding of active centers.

CO oxidation catalysed by Pd-based bimetallic nanoalloys

“…14 Theoretical studies of the CO adsorption and oxidation have been carried out for Pd-Au, 15,16 Pd-Ag, 16 Pd-Pt, Cu-Pt, Pd-Rh, 17 Zr-Sc, 18 and Au-Cu 19 clusters. Great efforts have been devoted to developing highly efficient catalysts to remove the poisonous CO gas from car exhaust and from hydrogen gases used for fuel cells.…”

“…14 Theoretical studies of the CO adsorption and oxidation have been carried out for Pd-Au, 15,16 Pd-Ag, 16 Pd-Pt, Cu-Pt, Pd-Rh, 17 Zr-Sc, 18 and Au-Cu 19 clusters. 18 In the case of Au-Cu clusters adsorbed on the oxide surface, the co-adsorption of CO and O 2 (Langmuir-Hinshelwood) takes place. 20 Theoretical works propose both Langmuir-Hinshelwood (two molecules adsorb and the adsorbed molecules undergo a bimolecular reaction) and Eley-Rideal (one of the molecules adsorbs and the other one reacts with it directly from the gas phase) mechanisms.…”

“…Great efforts have been devoted to developing highly efficient catalysts to remove the poisonous CO gas from car exhaust and from hydrogen gases used for fuel cells. 14 Theoretical studies of the CO adsorption and oxidation have been carried out for Au-Pd, 15 Pd-Pt, Cu-Pt, Pd-Rh, 16 Zr-Sc, 17 and Au-Cu 18 clusters. Experimentally, catalytic CO oxidation over Pd-Ni has been reported recently.…”

“…15 If there is oxygen present in the system, such as in the case of Zr-Sc oxide clusters, oxygen atoms for CO oxidation are provided by the cluster. 17 In the case of Au-Cu clusters adsorbed on the oxide surface, the co-adsorption of CO and O 2 (Langmuir-Hinshelwood) takes place. 18 Thus, the Langmuir-Hinshelwood mechanism seems to be preferable for CO oxidation on bimetallic clusters.…”

CO2 Methanation on Cu-Cluster Decorated Zirconia Supports with Different Morphology: A Combined Experimental In Situ GIXANES/GISAXS, Ex Situ XPS and Theoretical DFT Study

“…In order to elucidate the reaction mechanism responsible for CO 2 methanation on the Cu 4 O 2 cluster at the zirconium oxide support, the DFT calculations have been carried out involving four hydrogenation steps of the reaction. Concerning the model of ZrO support, ZrO 2 subunits have been considered because they are involved in crystalline growth and the subunit Zr 12 O 24 has been selected based on findings from previous reactivity studies on Zr oxide . The chosen subunit of Zr 12 O 24 with Cu 4 O 2 has been optimized, and after an extensive search of isomers (cf.…”