First-Principles Study on Periodic Pt₂Fe Alloy Surface Models for Highly Efficient CO Poisoning Resistance

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Surface and sub-surface atomic arrangements are crucial for catalytic active sites in electrochemical reactions.
• Platinum-iron (Pt-Fe) alloys are investigated for their catalytic properties, with a focus on atom distribution and platinum (Pt) segregation.

Purpose of the Study:

• To investigate atom distribution and Pt segregation in Pt-Fe alloys using computational methods.
• To identify stable Pt-Fe surface alloy structures and their impact on CO poisoning resistance.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Monte Carlo simulations combined with the cluster-expansion approach.
• Electronic structure analysis and Crystal Orbital Hamilton Population (COHP) analysis.

Main Results:

• Pt atoms preferentially segregate to the surface, while Fe atoms enrich the sub-surface.
• A stable periodic Pt2Fe alloy surface model is predicted at low Pt content and low annealing temperatures.
• Formation of the Pt2Fe surface alloy lowers the Pt d-band center, weakening CO adsorption and improving CO poisoning resistance.

Conclusions:

• The Pt2Fe surface alloy model offers enhanced resistance to CO poisoning.
• Controlling defect density in Pt-Fe alloys is a viable strategy for designing efficient electrocatalysts.
• Periodic Pt2Fe surface models provide computational guidance for developing advanced Pt-based catalysts.