Anomalous interfacial dynamics of single proton charges in binary aqueous solutions

Area of Science:

• Surface science
• Electrochemistry
• Physical chemistry

Background:

• Understanding charge transfer at solid-liquid interfaces is crucial for energy applications.
• Limited spatial and temporal resolution hinders detailed analysis of interfacial dynamics.
• Solvent effects on interfacial charge transport remain poorly understood.

Purpose of the Study:

• To investigate the dynamics of proton charge transport at the solid-liquid interface with single-charge resolution.
• To elucidate the influence of solvent composition on interfacial proton dynamics.
• To correlate interfacial dynamics with solvation properties.

Main Methods:

• Utilized single-molecule localization microscopy (SMLM) on emissive crystal defects in hexagonal boron nitride (hBN).
• Studied proton dynamics at the hBN-liquid electrolyte interface using binary mixtures of water and organic solvents (alcohols, acetone).
• Observed correlated activation between ionizable surface defects mediated by single excess proton transport.

Main Results:

• Demonstrated single excess proton transport along the solid/liquid interface.
• Observed correlated activation between adjacent ionizable surface defects.
• Found that solvent composition significantly impacts interfacial dynamics, increasing surface diffusivity and proton affinity at intermediate water fractions.
• Evidenced the notable role of solvation on interfacial proton charge transport.

Conclusions:

• Solvation plays a critical role in interfacial proton charge transport dynamics.
• The composition of the liquid electrolyte significantly modulates proton behavior at solid surfaces.
• Advanced microscopy techniques enable probing interfacial charge dynamics at the single-charge scale.