Tuning hydrogen bond network connectivity in the electric double layer with cations

Area of Science:

• Physical Chemistry
• Surface Science
• Computational Chemistry

Background:

• Hydrogen bond (H-bond) network connectivity in electric double layers (EDLs) is crucial for interfacial electrocatalytic processes like hydrogen evolution (HER) and hydrogen oxidation (HOR).
• The potential cation-specific effects on H-bond network connectivity within EDLs remain largely unexplored.

Purpose of the Study:

• To investigate whether different cations can tune the H-bond network connectivity in EDLs at the Pt(111)/water interface.
• To elucidate the role of cation hydration and interfacial water structure in modulating EDL properties.

Main Methods:

• Utilized *ab initio* molecular dynamics simulations.
• Analyzed the structure and connectivity of H-bond networks in EDLs under varying surface charge densities.
• Examined the interplay between cation hydration and interfacial water structure.

Main Results:

• Demonstrated that cations at the Pt(111)/water interface can indeed tune EDL structure and H-bond network connectivity.
• Observed a marked decrease in H-bond network connectivity for Na+ and Ca2+ systems as surface charge density became more negative.
• Reported a slight increase in H-bond network connectivity for the Mg2+ system under similar conditions.

Conclusions:

• Cation identity significantly influences H-bond network connectivity in EDLs.
• The hydration of cations and the resulting interfacial water structure are key factors governing H-bond network connectivity.
• These findings underscore the importance of cations in interfacial electrocatalysis.