# Long-Range Redox and Water Activation at Metal–Water Interfaces with Ferroelectric Ordering

## TL;DR

This paper explores how ordered water layers at metal interfaces affect electron transfer and redox processes.

## Contribution

The study reveals long-range redox effects mediated by ordered water layers at ferroelectric metal-water interfaces.

## Key findings

- Electron transfer occurs between metal Fermi levels and water molecules via ordered dipole layers.
- Ferroelectric ordering strongly couples with long-range redox phenomena at dipolar solvent structures.
- Ordered interface models have limitations in capturing long-range electron transfer effects.

## Abstract

The molecular structure of water has profound influence
on electron
transfer and redox processes at metal–water interfaces. While
ab initio molecular dynamics simulations provide an accurate description
of the interfacial structure, the respective computational cost is
often prohibitive. Static simulations using a few ordered water layers
can serve as a pragmatic alternative maintaining an explicit description
of molecular interactions at an affordable computational cost. We
here study the coupling between electronic and structural degrees
of freedom at ferroelectrically ordered metal–water interfaces.
With increasing number of ice-like water layers, we observe a long-range
transfer of electrons between the metal’s Fermi level and HOMO/LUMO
states of the outermost water molecules, mediated by ordered solvent
dipole layers. Our findings reveal limitations of the applicability
of the ordered interface model and reveal a strong coupling between
ferroelectric ordering and long-range (auto)­redox phenomena at dipolar
solvent structures, shedding new light onto the long-standing question
on the existence and stability of ferroelectric ice. Implications
for the activation of water molecules in electrocatalytic reactions
at charged metal–water interfaces are suggested.