CO oxidation catalysed by Pd-based bimetallic nanoalloys

Abstract

Density functional theory based global geometry optimization has been used to demonstrate the crucial influence of the geometry of the catalytic cluster on the energy barriers for the CO oxidation reaction over Pd-based bimetallic nanoalloys. We show that dramatic geometry change between the reaction intermediates can lead to very high energy barriers and thus be prohibitive for the whole process. This introduces challenges for both the design of new catalysts, and theoretical methods employed. On the theory side, a careful choice of geometric configurations of all reaction intermediates is crucial for an adequate description of a possible reaction path. From the point of view of the catalyst design, the cluster geometry can be controlled by adjusting the level of interaction between the cluster and the dopant metal, as well as between the adsorbate molecules and the catalyst cluster by mixing different metals in a single nanoalloy particle. We show that substitution of a Pd atom in the Pd5 cluster with a single Ag atom to form Pd4Ag1 leads to a potential improvement of the catalytic properties of the cluster for the CO oxidation reaction. On the other hand, a single Au atom does not enhance the properties of the catalyst, which is attributed to a weaker hybridization between the cluster's constituent metals and the adsorbate molecules. Such flexibility of properties of bimetallic nanoalloy clusters illustrates the possibility of fine-tuning, which might be used for design of novel efficient catalytic materials.

DFT global optimisation of gas-phase and MgO-supported sub-nanometre AuPd clusters

“…Au m Pd 1 m = 3-5 clusters have the same structures as the corresponding pure Au clusters, as previously reported. 35,50 Au m Pd 1 m = 6 adopts a Pd-centred planar hexagon which is also the core of the clusters with 7 and 8 Au atoms. The cluster for m = 9 also has a planar global minimum.…”

Altering CO binding on gold cluster cations by Pd-doping

“…53 The interaction is also enhanced for N = 4 and 6, but reduced for N = 5 after doping a single Pd atom in the Au N + clusters. 54 While doping a single atom of Au does not change the catalytic properties of the Pd 5 cluster for CO oxidation, 55 enhanced CO oxidation activity has been observed for Au 1 Pd 4 deposited on a TiO 2 (110) surface. 56 Stronger CO adsorption has also been predicted for doping vanadium into Au N (N = 2-14) clusters.…”

Pd1/BN as a promising single atom catalyst of CO oxidation: a dispersion-corrected density functional theory study

“…And the h-BN supported single atomic Au 11 , Ru 12 , Co 18 , Cu 19 , Pt 20 and Fe 21 promote the CO oxidation at the low temperature. Pd and its alloy, as the typical catalysts for CO oxidation, present high activity 22,23 .…”