CO adsorption on Ag(100) and Ag/MgO(100)

Area of Science:

• Surface Science
• Computational Chemistry
• Materials Science

Background:

• Understanding metal-adsorbate interactions is crucial for catalysis and materials design.
• Silver films on oxide supports are relevant for various catalytic applications.
• The electronic properties of metal overlayers can be influenced by the underlying substrate.

Purpose of the Study:

• To theoretically investigate carbon monoxide (CO) adsorption on a two-layer silver (Ag) film.
• To study the effect of a magnesium oxide (MgO) support on CO adsorption on Ag films.
• To analyze the influence of silver lattice structure on adsorption properties.

Main Methods:

• Ab initio calculations using configuration interaction (CI) level of theory.
• Embedding methods were employed to model the metal-adsorbate interface and the ionic solid.
• Two Ag film structures were considered: bulk Ag-Ag distances and expanded lattice.

Main Results:

• Calculated adsorption energy of Ag(100) on MgO(100) is 0.58 eV per Ag interfacial atom.
• CO adsorption is most stable at an atop Ag site, with energies ranging from 0.12 to 0.19 eV.
• CO adsorption energy is reduced on the Ag/MgO system compared to unsupported Ag films, indicating a direct electronic effect from the MgO support.
• Expansion of the Ag-Ag distance also reduced CO adsorption energy.

Conclusions:

• The MgO support directly influences the electronic properties of the Ag overlayer, reducing CO adsorption energy.
• Silver lattice expansion further decreases CO adsorption strength on the Ag/MgO system.
• These findings provide insights into the design of supported metal catalysts with tailored adsorption properties.