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The Interplay between Interfacial Solvation and Surface Kinetics Tunes the Selectivity between Hydrogen Evolution and
Daniel Escalera-López1, Raquel Anastacio1, Carlos Gomez Rodellar1
1Department of Interface Science, Fritz-Haber Institute of the Max Planck Society, Berlin 14195, Germany.
Journal of the American Chemical Society
|June 29, 2026
Summary
Electrodeposition additives like polyquaternium-2 (PQ-2) can significantly alter zinc electrodeposition kinetics. PQ-2 addition suppresses competing hydrogen evolution and promotes efficient Butler-Volmer kinetics, improving metal deposition.
Area of Science:
- Electrochemistry
- Materials Science
- Surface Science
Background:
- Electrodeposition is crucial for various applications, including semiconductors and energy storage.
- The precise mechanism of how additives influence electrodeposition, particularly ion desolvation at the double layer, is poorly understood.
Purpose of the Study:
- To investigate the effect of the cationic additive polyquaternium-2 (PQ-2) on zinc electrodeposition kinetics.
- To elucidate how PQ-2 modulates double-layer electrostatics and affects Arrhenius activation parameters.
Main Methods:
- Overpotential-dependent Arrhenius analysis of Zn electrodeposition in alkaline electrolytes.
- Comparison of electrodeposition with and without PQ-2 additive.
- Quartz crystal microbalance and electron microscopy for surface analysis.
Main Results:
- Without PQ-2, electrodeposition competes with hydrogen evolution, showing complex activation energy behavior.
- Addition of PQ-2 suppresses this competition and leads to efficient Butler-Volmer kinetics.
- PQ-2 likely induces charge inversion, facilitating zincate ion approach and electron transfer, supported by surface morphology changes.
Conclusions:
- Electrolyte additives can fundamentally alter electrodeposition mechanisms.
- PQ-2 shifts the kinetics from a solvation-controlled to a surface-controlled regime, enhancing Zn deposition.
- Understanding interfacial effects is key to controlling electrochemical activity and selectivity.
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