The electrochemical-step asymmetry index

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Thermodynamic considerations of free-energy landscapes drive electrocatalyst development.
• Current methods often approximate electrocatalytic activity by focusing only on weak-binding adsorbates.
• This overlooks the importance of intermediate binding strengths in optimizing catalyst performance.

Purpose of the Study:

• To introduce a novel descriptor, the electrochemical-step asymmetry index (ESAI), for approximating electrocatalytic activity.
• To provide a more accurate method for evaluating electrocatalysts, particularly for the oxygen evolution reaction (OER).
• To incorporate the Sabatier principle into the analysis of free-energy changes.

Main Methods:

• Developed the electrochemical-step asymmetry index (ESAI) based on free-energy changes in mechanistic descriptions.
• Applied ESAI to analyze the oxygen evolution reaction (OER) electrocatalysts.
• Penalized both excessively strong and weak bonding of intermediate states.

Main Results:

• The ESAI provides a more comprehensive approximation of electrocatalytic activity compared to previous methods.
• The index accounts for the asymmetric nature of optimal free-energy landscapes, including overpotential and kinetic effects.
• ESAI represents a conceptual advancement over the electrochemical-step symmetry index (ESSI).

Conclusions:

• The ESAI offers a refined approach to assessing electrocatalyst performance by considering a broader range of binding interactions.
• This method facilitates a more thorough representation of the Sabatier principle in electrocatalysis.
• ESAI is a promising descriptor for the rational design of efficient OER electrocatalysts.