Space Charge, Modulating the Catalytic Activity of Single-Atom Metal Catalysts

Area of Science:

• Electrochemistry
• Materials Science
• Surface Science

Background:

• Electrode charging at the interface is crucial for electrochemical reactions.
• Interface space charge can alter reaction environments and active site charge density, affecting electrocatalytic activity.
• The specific role of space charge in electrocatalysis remains underexplored.

Purpose of the Study:

• To investigate the electrocatalytic role of space charge.
• To modulate space charge density (σ) independently of electrochemical potential.
• To develop a new descriptor for catalyst design considering space charge effects.

Main Methods:

• Exploiting the structural features of MeNC to control space charge density.
• Maintaining a constant electrochemical potential for the oxygen reduction reaction (ORR).
• Computational analysis to explain the effect of charge density polarization on active sites.

Main Results:

• Space charge density (σ) was found to directly control ORR activity.
• Computational models explained this control via inductive polarization of active site charge density, impacting turnover rates.
• A novel descriptor was developed to predict activity trends across different metal centers and pH conditions.

Conclusions:

• Space charge plays a critical, tunable role in electrocatalysis.
• The developed descriptor provides a new framework for optimizing catalyst design.
• Findings offer fresh insights into optimizing catalyst performance by considering space charge effects.