Designing Bimetallic Nanoparticle Catalysts via Tailored Surface Segregation

TL;DR

This paper investigates surface segregation in platinum-group bimetallic nanoparticles, using simulations and calculations to design catalysts with noble-metal-enriched surfaces that are cost-effective and highly active.

Contribution

It uncovers a common surface segregation phenomenon and proposes a strategy to intentionally enrich nanoparticle surfaces with noble metals to enhance catalytic performance.

Findings

Surface segregation is prevalent in platinum-group bimetallic nanoparticles.

A thermodynamic descriptor predicts segregation behavior effectively.

Pt-enriched surface nanoparticles show superior catalytic activity in propane dehydrogenation.

Abstract

Bimetallic nanoparticles serve as a vital class of catalysts with tunable properties suitable for diverse catalytic reactions, yet a comprehensive understanding of their structural evolution under operational conditions as well as their optimal design principles remains elusive. In this study, we unveil a prevalent surface segregation phenomenon in approximately 100 platinum-group-element-based bimetallic nanoparticles through molecular dynamics simulations and derive a thermodynamic descriptor to predict this behavior. Building on the generality and predictability of surface segregation, we propose leveraging this phenomenon to intentionally enrich the nanoparticle surface with noble-metal atoms, thereby significantly reducing their usage while maintaining high catalytic activity and stability. To validate this strategy, we investigate dozens of platinum-based bimetallic nanoparticles for propane dehydrogenation catalysis using first-principles calculations. Through a systematic examination of the catalytic sites on nanoparticle surfaces, we eventually identify several candidates featuring with stable Pt-enriched surface and superior catalytic activity, confirming the feasibility of this approach.