Restructuring of an Ir(210) electrode surface by potential cycling

Area of Science:

• Electrochemistry
• Surface Science
• Materials Science

Background:

• Iridium (Ir) single crystal electrodes are crucial for electrocatalysis.
• Understanding surface restructuring is key to optimizing catalytic performance.
• Electrochemical methods offer a pathway to control surface morphology.

Purpose of the Study:

• To investigate the electrochemical surface faceting and restructuring of Ir(210) single crystal electrodes.
• To compare electrochemically induced faceting with thermal faceting.
• To analyze the impact of structural changes on electrocatalytic activity.

Main Methods:

• Cyclic voltammetry (CV) to probe electrochemical behavior.
• In situ scanning tunneling microscopy (STM) for structural analysis.
• Potential cycling in 0.1 M H2SO4 solution.

Main Results:

• Electrochemical potential cycling between -0.28 and 0.70 V vs SCE induces surface faceting on Ir(210).
• Electrically faceted structures resemble thermally faceted Ir(210), forming polyoriented nano-pyramids.
• These nano-pyramids grow anisotropically up to 5 nm in height after 4 hours.
• Structural changes correlate with altered electrocatalytic activity for carbon monoxide adlayer oxidation.

Conclusions:

• Electrochemical potential cycling is an effective method for surface restructuring of Ir(210) electrodes.
• The induced faceting significantly influences the electrocatalytic properties, particularly for CO oxidation.
• This study provides insights into controlling Ir surface morphology for enhanced electrocatalytic applications.