O₂ activation by core-shell Ru₁₃@Pt₄₂ particles in comparison with Pt₅₅ particles: a DFT study.

Area of Science:

• Materials Science
• Surface Chemistry
• Computational Chemistry

Background:

• Understanding the catalytic activity of core-shell nanoparticles is crucial for developing efficient chemical processes.
• Platinum-based nanoparticles are widely studied for their catalytic properties, but alloying with other metals can tune their performance.
• The electronic structure of nanoparticles, particularly the d-band center and d-valence band-top, significantly influences their reactivity.

Purpose of the Study:

• To theoretically investigate the reaction of O2 with a Ru13@Pt42 core-shell nanoparticle.
• To compare the reactivity of Ru13@Pt42 with a pure Pt55 nanoparticle.
• To elucidate the factors governing the differences in O-O and O-OH bond cleavage and OOH formation between the two nanoparticle systems.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to study the reaction pathways.
• Calculations focused on O2 adsorption, activation barriers for bond cleavage (O-O and O-OH), and intermediate species formation (H, OOH).
• Analysis of electronic properties, including the d-band center and d-valence band-top, was performed to correlate structure with reactivity.

Main Results:

• Pt55 exhibited higher O2 binding energy and lower activation energy for O-O bond cleavage compared to Ru13@Pt42.
• Protonation and one-electron reduction on Pt42 led to exothermic H atom formation.
• OOH formation was more facile on Ru13@Pt42 due to weaker metal-O2 and metal-H bonds, attributed to its lower-energy d-valence band-top and d-band center.

Conclusions:

• The Ru13@Pt42 core-shell nanoparticle displays lower reactivity in O2 reactions than Pt55.
• The electronic properties, specifically the low-energy d-valence band-top and d-band center of Ru13@Pt42, are responsible for its reduced catalytic activity.
• These findings highlight the importance of electronic structure in designing efficient core-shell nanocatalysts.