Reactions of O₂ with the Fe₁₉, Fe₉Pt₁₀ and Pt₁₉ clusters: a computational study

Area of Science:

• Computational chemistry
• Materials science
• Surface science

Background:

• Understanding metal cluster interactions with oxygen is crucial for catalysis and materials design.
• FePt alloys are promising for various applications, but their surface reactivity requires detailed investigation.
• Previous studies have focused on bulk materials, necessitating research on nanoscale cluster behavior.

Purpose of the Study:

• To investigate the interaction of molecular oxygen (O2) with Fe19, Pt19, and Fe9Pt10 clusters.
• To determine the lowest energy configurations of Fe-Pt clusters with near 1:1 stoichiometry.
• To elucidate the O2 dissociation pathways and binding energies on these distinct cluster types.

Main Methods:

• Density Functional Theory (DFT) calculations within the Generalized Gradient Approximation (GGA).
• Systematic search for lowest energy isomers of Fe-Pt clusters (2 <= n <= 8).
• Simulation of O2 dissociation reactions and optimization of oxygenated cluster structures (Fe19On, Fe9Pt10On, Pt19On, n=1-2).

Main Results:

• Distinct O2 dissociation patterns were observed for Fe19, Pt19, and Fe9Pt10 clusters.
• Fe19 and Fe9Pt10 clusters exhibit single transition states for O2 dissociation, with Fe19 showing spin relaxation branches.
• Pt19 displays a more complex, four-step O2 dissociation pathway; O2 desorption energy from Fe9Pt10O2 is higher than the average of Fe19O2 and Pt19O2.

Conclusions:

• The Fe9Pt10 cluster, with near 1:1 Fe:Pt ratio, shows unique O2 interaction properties compared to pure Fe19 and Pt19 clusters.
• The O2 dissociation mechanism and binding energies are highly dependent on the cluster composition and structure.
• Results indicate a potential chemical bias towards iron in Fe-Pt clusters regarding oxygen interaction.