Influence of coverage on adsorbate diffusion measurements at electrode surfaces by in situ linear optical diffraction

Area of Science:

• Surface science
• Electrochemistry
• Materials science

Background:

• Surface mass transport is crucial for electrochemical processes.
• In situ linear optical diffraction offers a novel approach to study surface dynamics.
• Understanding adlayer behavior is key to controlling electrode surface properties.

Purpose of the Study:

• To investigate surface mass transport of sulfur adsorbates on Pt(111) electrodes.
• To analyze the temporal evolution of linear optical diffraction intensity.
• To correlate diffraction signal decay with adlayer coverage and mobility.

Main Methods:

• Utilizing in situ linear optical diffraction.
• Conducting experiments in 0.1M H2SO4 electrochemical environment.
• Employing simulations of time-dependent diffusion profiles.
• Analyzing experimental data for sulfur adsorbates on Pt(111).

Main Results:

• Diffraction signal decay shows two time scales at low/medium sulfur coverage, linked to coverage-dependent diffusion.
• High sulfur coverage exhibits ultra-slow decay or cessation of decay.
• Ordered, high-density adlayer phases with low mobility were identified at high coverage.

Conclusions:

• Linear optical diffraction is effective for studying surface mass transport in electrochemical systems.
• Coverage-dependent diffusion and ordered adlayer phases significantly impact surface transport dynamics.
• Quantitative surface transport rates can be extracted using this diffraction method.