Coverage dependence of oxygen decomposition and surface diffusion on rhodium 111: a DFT study

Area of Science:

• Surface science
• Computational chemistry
• Catalysis

Background:

• Understanding oxygen interactions on metal surfaces is crucial for catalysis.
• Rhodium (Rh) based catalysts are important for nitrogen oxide (NOx) reduction.
• Previous studies lack detailed insights into oxygen behavior on Rh(111) at varying coverages.

Purpose of the Study:

• To systematically investigate oxygen adsorption, decomposition, and diffusion on Rh(111) using density functional theory (DFT).
• To determine the influence of coadsorbed oxygen molecules on these processes.
• To provide insights relevant to rhodium-catalyzed NOx decomposition systems.

Main Methods:

• Density functional theory (DFT) calculations.
• Potential energy hypersurface (PES) calculations using linear/quadratic synchronous transit and conjugate gradient methods.
• Analysis of oxygen adsorption strength, dissociation pathways, and atomic oxygen diffusion barriers.

Main Results:

• Oxygen adsorption strength on Rh(111) decreases with increasing coverage, indicating self-inhibition.
• Low oxygen coverage enhances oxygen molecule decomposition, while high coverage inhibits it.
• Activation energy for atomic oxygen diffusion on Rh(111) increases with oxygen coverage.

Conclusions:

• Oxygen coverage significantly impacts adsorption, decomposition, and diffusion kinetics on Rh(111).
• The findings suggest a complex, coverage-dependent role of oxygen in rhodium-catalyzed reactions.
• This work provides a fundamental understanding for designing efficient rhodium-based catalysts for NOx decomposition.