Hydrogen bonding in mixed OH+H2O overlayers on Pt(111)

Area of Science:

• Surface Science
• Physical Chemistry
• Materials Science

Background:

• Understanding the stability of surface species like hydroxyl (OH) on metal catalysts is crucial for designing efficient catalytic processes.
• Hydrogen bonding plays a significant role in the self-assembly and stability of molecular overlayers on surfaces.

Purpose of the Study:

• To investigate the stability of hydroxyl (OH) on the Pt(111) surface.
• To determine the role of hydrogen bonding in stabilizing the OH overlayer.
• To confirm density-functional theory (DFT) predictions regarding the optimal structure.

Main Methods:

• Experimental investigation of OH stability on Pt(111).
• Analysis of surface structures and overlayer compositions.
• Utilizing density-functional theory (DFT) predictions for comparison.

Main Results:

• The optimal structure for OH on Pt(111) is a mixed hydroxyl-water (OH+H2O) phase.
• A hexagonal (sqrt[3]xsqrt[3])R30°-(OH+H2O) lattice with a weak (3x3) superstructure is formed due to ordered hydrogen bonds.
• The mixed overlayer's stability decreases with reduced H2O content, leading to defects and destabilization.

Conclusions:

• Hydrogen bonding is essential for stabilizing the OH overlayer on Pt(111).
• The mixed OH+H2O phase is more stable than pure OH.
• Disruption of the hydrogen-bonding network by lowering H2O content leads to overlayer instability.