Reviewed by Danielle Ellis, B.Sc.Sep 24 2024
A research team at the University of Xiamen has created a machine learning potential for Pt-water interfaces. This study used molecular dynamics machine learning to uncover the complex interactions at the Pt (211)/water interface. The simulations revealed different types of water molecules and anisotropic behavior, offering in-depth insights into the structure and dynamics of water molecules at the Pt/water interface. This knowledge is essential for clarifying interfacial processes that are essential to electrochemical reactions, like ion solvation and water dissociation. The study has been published in the journal Materials Futures.
Structure and dynamics at Pt(211)/water interface. Image Credit: Jun Cheng and Fei-Teng Wang from the University of Xiamen
The electrocatalytic performance of the stepped Pt surfaces is higher than that of the basal Pt planes. Compared to basal planes, stepped surfaces have a higher density of low-coordination atoms, such as edge and corner atoms. Stronger adsorption and more advantageous interactions with reactant molecules are made possible by the higher chemical reactivity of these low-coordination sites, which increases catalytic activity. However, the solvation of ions, the adsorption of reactants, and the kinetics of electrochemical reactions can all be strongly impacted by the arrangement and behavior of the interfacial water molecules.
Understanding the fundamental mechanisms behind various applications in energy conversion and material science requires revealing the in-situ details of water structures at these stepped Pt/water interfaces. Determining the interfacial water structures at ambient conditions with high temporal and spatial resolution remains a formidable challenge.
Although they offer a means of examining the interfacial structures, ab initio molecular dynamics simulations are expensive to compute. Thus, it is crucial to create an accurate and efficient method for conducting molecular dynamics simulations to investigate the molecular underpinnings of many interfacial phenomena.
The Solution
A team from the University of Xiamen reported machine learning molecular dynamics (MLMD) simulations of the Pt(211)/water interfaces. The results reveal different types of chemisorbed and physisorbed water molecules within the adsorbed layer. Three unique water pairs are observed between these adsorbed water molecules, which may serve as key precursors for water dissociation.
These interfacial water structures influence the anisotropic dynamics (diffusion, reorientation, and hydrogen bond dynamics) of the adsorbed water layer. The study provides the theoretical foundation for the experimental investigation of the in-situ interfacial dynamics and structures.
The Future
Subsequent studies will investigate the dynamic properties at longer timescales at the interfaces between stepped metal and water and make links with the experimental observables.
The Impact
The prominent water pairs formed at the interface provide a promising means of deciphering the anisotropic properties at stepped metal/water interfaces.
Journal Reference:
Wang, F., et al. (2024) Water structures and anisotropic dynamics at Pt(211)/water interface revealed by machine learning molecular dynamics. Materials Futures. doi.org/ 10.1088/2752-5724/ad7619