Size and structure effects of PtN (N = 12 − 13) clusters for the oxygen reduction reaction: First-principles calculations

Abstract

Size and structure effects on the oxygen reduction reaction on PtN clusters with N = 12-13 atoms have been investigated using periodic density functional theory calculations with the generalized gradient approximation. To describe the catalytic activity, we calculated the O and OH adsorption energies on the cluster surface. The oxygen binding on the 3-fold hollow sites on stable Pt12-13 cluster models resulted more favorable for the reaction with O, compared with the Pt13(Ih) and Pt55(Ih) icosahedral particles, in which O binds strongly. However, the rate-limiting step resulted in the removal of the OH species due to strong adsorptions on the vertex sites, reducing the utility of the catalyst surface. On the other hand, the active sites of Pt12-13 clusters have been localized on the edge sites. In particular, the OH adsorption on a bilayer Pt12 cluster is the closest to the optimal target; with 0.0-0.2 eV weaker than the Pt(111) surface. However, more progress is necessary to activate the vertex sites of the clusters. The d-band center of PtN clusters shows that the structural dependence plays a decisive factor in the cluster reactivity.

Structural Evolution and Electronic Properties of Intermediate Sized Tin(n=33--60) Clusters

“…We further have calculated the d-band center of the clusters which is an important parameter to determine the reactivity of clusters and surfaces. [48] The results of 𝜖 d are similar than 𝜂 suggesting the reduction of reactivity of the clusters with the increase of the size. The variation of 𝜖 d help us to corroborate the magnetic character of the clusters.…”

Exploring Structural Diversity and Fluxionality of Ptn (n = 10–13) Clusters from First-Principles

“…26,33−35 The same global minimum was also found for Pt 12 . 26 Including spin−orbit coupling was found to have a minor impact (∼0.01 eV) on the relative energy between lowenergy structures, 26,36 so we did not consider it in the present work. The putative global minimum for Pt 11 as a highly disordered geometry (Figure 2b) is, however, dissimilar from other proposed structures in the literature.…”

Origin of high oxygen reduction reaction activity of Pt12 and strategy to obtain better catalyst using sub-nanosized Pt-alloy clusters

“…Using a few optimized geometries, Rodríguez-Kessler et al . showed that the adsorption energies of O/OH and Pt 12 /Pt 13 depend on the cluster geometries19. Since the atomic charge of an O atom represents the amount of charge transfer between it and Pt-based ORR catalysts, it has often been considered that the atomic charge on an O atom should be a good indicator for the adsorption strength.…”

“…For example, Rodríguez-Kessler et al . have mentioned that O/OH adsorption energies for Pt 12 /Pt 13 depend on the cluster geometries, i.e., fluctuation19. It should be noted that the adsorption energies have often been utilized as simple indicators of ORR activity202122.…”