Molecular and Electronic Structures at Electrochemical Interfaces from In Situ Resonant X-Ray Diffraction

Area of Science:

• Electrochemistry
• Surface Science
• Materials Science

Background:

• Understanding electrochemical interfaces is crucial for controlling electrochemical reactivity.
• Atomic-level characterization of these interfaces remains a significant challenge.
• Electrochemical interfaces govern many catalytic and energy conversion processes.

Purpose of the Study:

• To develop and apply an original approach for atomic-level characterization of electrochemical interfaces.
• To determine the molecular and electronic structures of the interface layer and charge distribution.
• To gain unique insights into water-metal interactions at electrochemical interfaces.

Main Methods:

• Utilized in situ surface resonant X-ray diffraction (SRXRD) experiments.
• Performed simulations using first-principle density functional theory (DFT) calculations.
• Studied the Pt(111) electrode in an acidic medium at an applied potential without specific adsorption.

Main Results:

• Determined the molecular and electronic structures of the ionic layer at the interface.
• Revealed the charge distribution within the surface metal layers of the electrode.
• Identified a positively charged counter layer (1.60 water and 0.15 hydronium molecules per Pt unit cell) at 2.8 Å from the Pt(111) surface.

Conclusions:

• The combined SRXRD and DFT approach provides atomic-level insights into electrochemical interfaces.
• A distinct molecular and electronic structure of the interface layer was elucidated.
• The findings offer a unique perspective on water-metal interactions in electrochemical systems.