Why Proton Grotthuss Diffusion Slows down at the Air–Water Interface while Water Diffusion Accelerates

The Journal of Physical Chemistry Letters, Journal Year: 2025, Volume and Issue: unknown, P. 2645 - 2653

Published: March 5, 2025

Excess proton diffusion at aqueous interfaces is crucial for applications including electrocatalysis, aerosol chemistry, and biological energy conversion. While have been proposed as pathways channeling protons, remains far less understood than in the bulk. Here we focus on air-water interface use density functional theory-based deep potential molecular dynamics simulations to reveal contrasting interface's impacts: excess slows down compared bulk, while water accelerates. This contrast stems from reduced hydrogen-bond coordination interface, which facilitates transient unstable rattling but impedes stable hops central Grotthuss diffusion. As a result, protons molecules diffuse comparable rates, stark departure bulk behavior. mechanistic insight delineates distinct limiting regimes bulk-enhanced interfacial diffusion, with important implications chemistry.

Language: Английский

Isotropic ↔ anisotropic surface geometry transitions induced by adsorbed surfactants at water/vapor interfaces

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 161(18)

Published: Nov. 14, 2024

Adsorbates at a water/vapor interface change the surface geometry through altered tension, yet detailed theoretical studies are relatively sparse, and many applications focus on ensemble average characteristics. Here, we demonstrate that different interpretations of emerge when considering distributions curvature orientation as function adsorbed surfactant concentration sterics. At low densities, tributyl phosphate (TBP) sorbed has an increased presence ridges defined by principal curvatures κ1 κ2 opposite signs close in magnitude. As TBP density increases, difference slowly increases. There is distinct transition geometry, where ridge-like features become much more pronounced, having sides whose normal to flat interfacial plane. Thus, added surface, anisotropic terms magnitude κ2. We label this isotropic → geometric transition. Comparing carbon tail length alkyl reveals smaller surfactants also anisotropically enhance tails stabilize increase symmetry waves along two axes. These results reflect opportunity incorporate realistic within collective understanding statistical theories surfaces, including capillary wave theory.

Language: Английский