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O: Fachverband Oberflächenphysik

O 65: Solid-liquid interfaces: Reactions and electrochemistry II

O 65.8: Vortrag

Mittwoch, 11. März 2026, 16:45–17:00, TRE/PHYS

First Steps Matter Most: Free Energy Barriers of the Volmer Step in Hydrogen Evolution at Pt(111) — •Barbara Sumić, Karsten Reuter, and Nicolas G. Hörmann — Fritz-Haber-Institut der MPG, Berlin

The Hydrogen Evolution Reaction (HER) plays a central role in hydrogen-based energy conversion. The initial Volmer step, involving proton adsorption at the electrode interface, is key to understanding reaction kinetics and the influence of pH. Conventional approaches to estimating barrier heights based on density-functional theory are limited by the need for reduced system sizes and short simulation times, which restrict statistical sampling and hinder fully converged free-energy calculations, particularly when solvent reorganisation is involved.
Here, we explore machine-learned interatomic potentials (MLIPs) combined with enhanced sampling techniques to gain more comprehensive insight into the reaction mechanism and barrier for the Volmer step at Pt(111) in dynamically described interfacial water. Using data-driven collective variables, we aim to capture dynamic environmental and solvent effects that are difficult to access with standard sampling. We also investigate the applicability of the RAZOR (Response Analysis in z-ORientation) framework [1] for barrier calculations at applied bias to probe potential-dependent behavior.
Together, these approaches provide a pathway toward more consistent and physically grounded modelling of HER across different pH conditions.
[1] N. Bergmann et al., Phys. Rev. Lett. 135, 146201 (2025).

Keywords: Hydrogen Evolution Reaction; Electrocatalysis; Machine Learnt Interatomic Potentials; Barrier Calculation