Enabling Generalized Coordination Numbers to Describe Strain Effects

Abstract

The world's growing energetic demand calls for efficient generation and interconversion of different types of energy. Heterogeneous catalysis can help cope with such demand, provided that rational, accurate and affordable design methods lead to the discovery of cost-effective and efficient catalysts. Here we derive a simple descriptor to simultaneously capture two parameters commonly used in catalytic materials design: strain and coordination. We test the descriptor with four different adsorbates on four active sites of two metals, and applying strain in the range of ±3 %, usually observed experimentally at catalytic metal surfaces. Furthermore, we use the descriptor to illustrate catalyst design availing strain and nearest-neighbor effects simultaneously for the oxygen reduction reaction, a reaction of high importance in fuel cells. The connection between coordination and strain helps in the search for robust yet rapid catalyst design methodologies.

Influence of Van der Waals Interactions on the Solvation Energies of Adsorbates at Pt‐Based Electrocatalysts

“…However, it is preferable not to extrapolate values of group 1 to group 2 and vice versa, as the differences are on average ∼0.15 eV. For instance, the design principle for oxygen reduction is that optimal catalysts should bind around 0.10–0.15 eV weaker than Pt(111) ( ), so it is advisable to avoid intergroup extrapolations. Table provides the average values (avg1/avg2) and standard deviations (stdev1/stdev2) for each alloy in each group.…”

Revealing the nature of active sites in electrocatalysis

“…To discern specically active surface congurations one can use CN 61 and its associated coordination-activity plots. 62,[67][68][69][70] As said before, for the ORR on Pt the activity is typically correlated to the adsorption energy of *OH, which according to the Sabatier principle should not be bound too strong nor too weak in order to enable an efficient electrocatalysis. Instead of the usual correlation between activity and binding properties, within the CN approach the correlations are based on the connection between coordination environment and adsorption energies as described in the previous section.…”

“…0.1-0.15 eV weaker *OH adsorption energy than Pt(111) terrace sites, 35 which is found at concave defects or strained (111) terraces. 20,62,67,73 In alkaline solutions the metal cations somehow modify *OH adsorption so that the optimal binding is found at (111) terraces. Thus, the presence of defects, either concave or convex, results in lower overall ORR performance for Pt electrodes in presence of alkali cations.…”

Escaping Scaling Relationships for Water Dissociation at Interfacial Sites of Zirconia-Supported Rh and Pt Clusters

“…2,40 Due to the irregularity of the cluster geometries, we also incor-porated the strain adjustment proposed in Ref. 27, resulting in the SGCN descriptor. The OH+H adsorption energies have been plotted against the SGCN values of the H adsorption sites in Figure 5b, from which it is evident that these quantities show no correlation with each other.…”

“…This is a slightly generalized version of the definition in Ref 40,. to allow for the inclusion of atoms other than fcc metals.The GCNs were refined by considering strain effects for the metal cluster atoms 27. This is done by including a factor describing the ratio of the optimal bulk bond length d bulk to the particular metal-metal bond length d(i, j):…”