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Tuning Acid-Base Chemistry at an Electrified Gold/Water Interface
Steffen Murke1, Wanlin Chen1, Simone Pezzotti1
1Department of Physical Chemistry II, Ruhr University Bochum, D-44801 Bochum, Germany.
Voltage significantly alters amino acid acidity (pKa) at metal-water interfaces. This study models potential-dependent shifts, offering new ways to control electrochemical reactions by tuning surface properties and applied voltage.
Area of Science:
- Electrochemistry
- Physical Chemistry
- Surface Science
Background:
- Acid-base reactions are fundamental in chemistry and electrochemistry.
- Macroscopic solution concepts like pKa and pH differ at electrified interfaces due to solvation and voltage.
Purpose of the Study:
- To measure the potential-dependent pKa of glycine at a gold/water interface.
- To develop a general model for understanding voltage-induced pKa shifts at interfaces.
Main Methods:
- Spectroscopic titration to measure pKa values.
- Computational simulations to support the proposed model.
Main Results:
- Observed significant shifts in glycine's pKa values with applied voltage.
- Developed a model linking pKa shifts to local hydrophobicity and electric fields.
Conclusions:
- Potential-dependent pKa shifts at electrified interfaces can be explained by local environmental factors.
- Tuning metal surfaces and applied voltage offers new avenues for controlling electrochemical reactivity.
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