A Universal Model of Cation Effects in Electrocatalysis.

Area of Science:

• Electrochemistry
• Surface Science
• Catalysis

Background:

• Electrolyte cations are often considered inert in electrocatalysis.
• Observed catalytic rates are frequently sensitive to cation identity, lacking a unified explanation.
• Previous explanations involved diverse physical phenomena across different reaction systems.

Purpose of the Study:

• To present a general electrostatic framework for understanding cation effects in electrocatalysis.
• To explain how cation arrangement at the electrode surface modifies the interfacial electric field.
• To identify criteria for the observation of cation effects.

Main Methods:

• Developing a theoretical model based on electrostatics.
• Analyzing cation arrangement (size, shape, solvation, packing) at the electrode surface.
• Considering the influence of the electric field on adsorbed intermediates and transition states.

Main Results:

• Cation arrangement dictates the interfacial electric field strength, influencing reaction energetics.
• Cation effects are observed when operating potential is negative of the potential of zero total charge and the reaction step is field-sensitive.
• The framework reconciles previously inconsistent trends in activity and selectivity across different catalysts and electrolytes.

Conclusions:

• The electrostatic model provides a unified explanation for cation effects in electrocatalysis.
• It offers conceptual and predictive value for designing new catalysts and electrolytes.
• Recognizing the role of electric fields in catalysis opens avenues for improved activity and selectivity.