Direct instrumental identification of catalytically active surface sites

Area of Science:

• Surface science
• Catalysis
• Electrochemistry

Background:

• Heterogeneous catalysts are crucial in 80% of chemical and energy processes.
• Catalyst activity depends on specific surface sites with optimal intermediate binding.
• Scanning tunnelling microscopy (STM) has advanced atomistic understanding but is not typically used for in-situ active site identification.

Purpose of the Study:

• To demonstrate that standard STMs can map catalytic activity with high spatial resolution.
• To identify catalytically active surface sites under reaction conditions.
• To aid the rational design of heterogeneous catalysts and electrocatalysts.

Main Methods:

• Utilizing common scanning tunnelling microscopes (STMs).
• Monitoring relative changes in tunnelling current noise.
• Distinguishing active sites based on their catalytic ability for specific reactions.

Main Results:

• Demonstrated high-resolution mapping of catalytic activity using STM.
• Successfully distinguished active sites for hydrogen-evolution and oxygen-reduction reactions by analyzing tunnelling current noise.
• Enabled quantitative evaluation of the contribution of different defects and inter-material boundary sites to overall catalyst activity.

Conclusions:

• Standard STMs can effectively map catalytic activity and identify active sites in real-time.
• The method provides a powerful tool for evaluating the role of surface defects and interfaces in catalysis.
• This approach is expected to significantly aid in the rational design of improved heterogeneous catalysts and electrocatalysts.