Finding optimal surface sites on heterogeneous catalysts by counting nearest neighbors

Area of Science:

• Heterogeneous catalysis
• Surface science
• Materials chemistry

Background:

• Catalytic activity is often linked to specific surface sites.
• Current methods like Sabatier plots guide catalyst design via adsorption energies, but lack geometric specificity.
• Devising new catalysts requires understanding the precise geometric structure of active sites.

Purpose of the Study:

• Introduce a novel method, "coordination-activity plots," to predict the geometric structure of optimal active sites.
• Illustrate the method's application to the oxygen reduction reaction (ORR) using platinum as a model catalyst.
• Provide a new guideline for designing highly active heterogeneous catalysts.

Main Methods:

• Development of "coordination-activity plots" based on the number of nearest neighbors.
• Application of the plots to analyze active sites on platinum surfaces for the ORR.
• Experimental validation of predicted active site structures on platinum (111) surfaces.

Main Results:

• Coordination-activity plots predict that sites with the same first-nearest neighbors as (111) terraces but more second-nearest neighbors exhibit superior catalytic activity.
• Highly active sites were successfully created on platinum (111) surfaces based on these predictions.
• The active sites were generated without alloying, using three distinct and cost-effective experimental techniques.

Conclusions:

• Coordination-activity plots offer a powerful new tool for predicting and designing optimal geometric structures of active sites in heterogeneous catalysis.
• This approach enables the rational design of highly active catalysts, exemplified by the enhanced platinum catalyst for ORR.
• The findings pave the way for developing more efficient and targeted catalytic materials.