Water at electrode-electrolyte interfaces: combining HOD vibrational spectra with ab initio-molecular dynamics...

Area of Science:

• Physical Chemistry
• Surface Science
• Computational Chemistry

Background:

• Understanding interfacial water structure is crucial for electrochemistry and material science.
• The hydrogen-bond network of water at interfaces is complex and sensitive to external stimuli.

Purpose of the Study:

• To investigate the structure and potential dependence of interfacial water.
• To elucidate the hydrogen-bond network and molecular orientation at the gold-water interface.

Main Methods:

• Vibrational spectroscopy using H2O:D2O mixtures to study HOD and H2O modes.
• Potential-dependent *ab initio* simulations of the gold-water interface.

Main Results:

• Identified O-H and O-D stretching modes and bending modes of HOD and H2O.
• Observed reorientation of interfacial water around a stable, parallel hydrogen-bond backbone.
• Found no evidence of an ice-like first layer of interfacial water at any applied potential.

Conclusions:

• Interfacial water structure is significantly influenced by the applied electrode potential.
• At positive potentials, water donates hydrogen bonds; at negative potentials, it accepts them, but donation persists.
• The study provides a deeper insight into the dynamic and structured nature of water at electrified interfaces.