Interface between platinum(111) and liquid isopropanol (2-propanol): a model for molecular dynamics studies

Area of Science:

• Surface Science
• Physical Chemistry
• Computational Chemistry

Background:

• Understanding molecular adsorption on metal surfaces is crucial for catalysis and materials science.
• Isopropanol adsorption on platinum is relevant for various chemical processes.
• Previous experimental studies provide limited insight into the dynamic and structural details at the molecular level.

Purpose of the Study:

• To investigate the adsorption behavior of isopropanol on a platinum(111) surface using molecular dynamics.
• To analyze static and dynamic properties of the platinum-isopropanol interface across different coverage regimes.
• To elucidate the structural organization and molecular mobility at the interface.

Main Methods:

• Development and application of a molecular dynamics model with a specific parametrization procedure.
• Simulation of isopropanol adsorption on platinum(111) at unsaturated and oversaturated coverages.
• Analysis of adsorption energy, density profiles, atom distribution, molecular orientation, and mobility.

Main Results:

• Adsorption energy increases with coverage at unsaturated levels but decreases at oversaturated (multilayer) conditions.
• A distinct molecular packing forms at the interface, featuring a hydrophobic methyl brush, followed by depletion and oscillating density layers up to 3 nm.
• Molecular orientation is primarily governed by atom distribution, not direct chemical interactions, except for hydrogen bond formation in the first layer; mobility is restricted to the first layer.

Conclusions:

• The study provides a detailed molecular-level understanding of isopropanol adsorption on Pt(111).
• The hydrophobic methyl brush significantly influences the multilayer structure and dynamics.
• Surface-adsorbate interactions primarily affect the first adsorbed layer's properties, with limited impact on higher layers.