Speaker
Description
Electrified solid-liquid interfaces are highly relevant in electrochemical energy transformation devices such as fuel cells and electrolyzers. In the context of aqueous electrochemistry, it is in particular the detailed interfacial water structure that is believed to critically affect the function of these devices. In predictive-quality molecular modeling, ab initio molecular dynamics (AIMD) simulations with explicit water are the present gold standard to achieve insight into this water structure. However, the high computational cost limits their applicability to benchmarks for selected model systems. Intermediate to effective implicit solvation approaches, there is correspondingly a long-standing interest in using static ice layers as an efficient solvation model. To date, such static solvation layers are typically created manually and in an ad hoc fashion though.
Aiming to put this on a more systematic footing, we develop a general protocol to generate ensembles of structurally diverse, low-energy 2D static water films for low-index metal surfaces [1]. The construction recipe presently focuses on the first water layer and leverages lattice-matching algorithms in combination with a database of 2D water films. In the application to Pt(111), the interfacial structure of the first solvation shell, the adsorption energy and the point of zero charge obtained by this 2D static water (2DSW) approximation is then systematically compared to results obtained from extensive AIMD simulations.
While we find some structural overlap between static and dynamic water ensembles, static structures tend to overemphasize the in-plane hydrogen bonding network. This feature is especially pronounced for the widely used low-temperature hexagonal ice-like structure. In addition, a complex relation between structure, work function, and adsorption energy is observed, which reveals that the focus on single, static water models may introduce systematic biases. This bias can be reduced by averaging over consistently created 2DSW structural ensembles as produced by our protocol. Notably, resulting errors are then comparable to those of implicit solvation approaches, but without the need for system-specific empirical parameters. Ongoing work now concentrates on introducing a flexible response of the water layers to explicit surface charging and the presence of adsorbates, as well as to use the 2DSW structures as suitable starting points for short-time AIMD trajectories.
[1] A.C. Dávila López, T. Eggert, K. Reuter, and N. G. Hörmann, J. Chem. Phys. 155, 194702 (2021).
| Abstract Number (department-wise) | TH 09 |
|---|---|
| Department | TH (Reuter) |
