Scanning Electrochemical Microscopy of Single-Crystal Platinum Electrode

Area of Science:

• Electrochemistry
• Surface Science
• Analytical Chemistry

Background:

• Single-crystal metal electrodes offer atomic-level surface control, ideal for fundamental electrochemical studies.
• Traditional methods like the hanging meniscus configuration are incompatible with Scanning Electrochemical Microscopy (SECM).
• SECM requires an upward orientation of the sample surface relative to the ultramicroelectrode tip.

Purpose of the Study:

• To develop a precision glass cell enabling SECM analysis of a disk Pt(111) substrate.
• To investigate redox dynamics of underpotential hydrogen deposition, hydroxyl adsorption, and hydrogen oxidation on Pt(111) using SECM.
• To clarify the origin of the characteristic butterfly peaks observed during electrochemical analysis of Pt(111).

Main Methods:

• Fabrication of a novel, contamination-free glass cell for SECM.
• Preparation of a flame-annealed Pt(111) disk electrode within the glass cell.
• Cyclic voltammetry in acidic electrolytes (HClO4, H2SO4) to confirm surface cleanliness and characteristic peaks.
• In situ SECM measurements to monitor electrochemical reactions under the ultramicroelectrode tip.

Main Results:

• The new glass cell successfully accommodates the Pt(111) disk, preventing contamination and leakage.
• SECM successfully monitored redox dynamics, including hydrogen deposition and oxidation, coupled with proton transfer.
• A sharp butterfly peak was observed on the Pt(111) substrate, while the tip current showed minimal change, suggesting a non-faradaic origin.

Conclusions:

• The developed glass cell is effective for in situ SECM of single-crystal electrodes like Pt(111).
• The study provides new insights into the electrochemical behavior of Pt(111), particularly the origin of butterfly peaks.
• This methodology will advance the study of electrocatalytic reactions and intermediates on various single-crystal metal surfaces.