Diffusion barriers, growth pathways, and scaling relations for small supported metal clusters

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Nanocatalyst degradation via sintering limits their efficiency and lifespan.
• Understanding the diffusion of metal clusters on support materials is crucial for designing stable nanocatalysts.

Purpose of the Study:

• To investigate the diffusion pathways and energy barriers of small metal clusters (Pt, Au, Ag, Pd) on MgO(001) using ab initio density functional theory.
• To establish correlations between diffusion barriers, binding energies, cohesive energies, and melting temperatures of these metals.
• To explore the influence of cluster size and surface topography on diffusion behavior.

Main Methods:

• Ab initio density functional theory (DFT) calculations.
• Computation of diffusion pathways and energy barriers (E_d) for metal clusters (Pt_n, Au_n, Ag_n, Pd_n, n=1-4) on MgO(001).
• Analysis of correlations with bulk properties: binding energy (E_b), cohesive energy (E_coh), and melting temperature (T_m).

Main Results:

• Diffusion barriers and sintering energies are generally highest for Platinum (Pt), showing a trade-off between kinetics and thermodynamics.
• Smooth positive correlations were found between E_d and E_b, E_b and E_coh, E_coh and T_m, and E_d and T_m.
• Diffusion trends varied with cluster size (monomers, trimers, tetramers vs. dimers) due to energy landscape topography.

Conclusions:

• Scaling relations between diffusion barriers and bulk metal properties (like T_m) can predict nanocatalyst sintering behavior.
• The findings provide insights into the stability of various metal nanocatalysts and guide the selection of materials for specific applications.
• Developed models can estimate diffusion barriers and sintering behavior, aiding in the design of more robust catalytic systems.