Attenuated total reflection surface-enhanced infrared absorption spectroscopy at a cobalt electrode

Area of Science:

• Electrochemistry
• Surface Science
• Spectroscopy

Background:

• Surface-enhanced infrared absorption spectroscopy (SEIRAS) is a powerful technique for studying surface chemistry.
• Conventional IR reflection-absorption spectroscopy (IRRAS) has limitations in sensitivity for certain surface analyses.
• Cobalt (Co) electrodes are of interest for various electrochemical applications.

Purpose of the Study:

• To extend in situ SEIRAS in an attenuated total reflection (ATR) configuration to a Co electrode.
• To characterize a novel Co-on-Au electrode structure for enhanced spectroscopic analysis.
• To investigate the detection limits and capabilities of SEIRAS for surface-bound molecules on Co.

Main Methods:

• Fabrication of a Co electrode via potentiostatic deposition of a Co overlayer onto a Au underlayer on an ATR Si prism.
• Characterization of the Co-on-Au film using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS).
• In situ SEIRAS measurements in phosphate buffer solution (PBS) to analyze surface probe CO molecules.

Main Results:

• AFM revealed island structures with smaller Co nanoparticles facilitating the SEIRA effect.
• XPS confirmed a virtually pinhole-free Co overlayer.
• SEIRAS detected linearly bonded CO (CO(L)) and multi-bonded CO (CO(M)) bands with significantly higher intensity than IRRAS.
• Stark tuning rates for CO(L) and CO(M) were determined, demonstrating enhanced detection capabilities.

Conclusions:

• The developed in situ SEIRAS-ATR method is effective for Co electrodes.
• The Co-on-Au electrode structure enhances SEIRA activity.
• This technique offers superior sensitivity for detecting surface species like CO on Co, enabling new insights into surface processes.