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Semiclassical Theory of Stepped Electrodes and Step Bunching
Zengming Zhang1,2, Michael Eikerling1,2, Jun Huang1,2
1Institute of Energy Technologies, IET-3: Theory and Computation of Energy Materials, Forschungszentrum Jülich GmbH, Jülich52425, Germany.
Journal of the American Chemical Society
|July 14, 2026
Summary
Atomic-scale steps on electrodes significantly impact electrochemical performance. Our study reveals how step microstructure and thermodynamics influence surface charging, predicting conditions for step bunching.
Area of Science:
- Electrochemistry
- Surface Science
- Materials Science
Background:
- Atomic-scale steps on electrode surfaces are known to influence electrochemical activity and stability.
- The microscopic mechanisms behind these step-induced behaviors, particularly structural instability, are not well understood.
Purpose of the Study:
- To investigate the microstructure and thermodynamics of the electrical double layer at stepped electrodes.
- To elucidate the mechanisms governing the electrochemical behavior and stability of stepped surfaces.
Main Methods:
- Utilized semiclassical density-potential functional theory.
- Analyzed differential capacitance and potential of zero free charge (PZFC) with varying step densities for gold (Au) and silver (Ag) electrodes.
Main Results:
- The theoretical model accurately reproduced experimental trends for differential capacitance and PZFC with step density.
- Demonstrated that the PZFC deviates from the potential of minimum capacitance at stepped electrodes, unlike flat electrodes.
- Introduced the concept of local PZFCs to account for heterogeneous surface charging.
Conclusions:
- Step-induced shifts in PZFC are linked to surface tension changes.
- Step bunching is predicted to be thermodynamically driven at more positive electrode potentials.
- Electrolyte composition significantly influences the behavior of stepped electrodes.
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