Ab Initio Molecular Dynamics with Explicit Solvation Reveals the Volmer–Heyrovsky Mechanism for Chlorine Evolution on Dimensionally Stable Anodes

The chlorine evolution reaction (CER) is the core anodic process in the chlor-alkali industry, where RuO2–TiO2 mixed oxides serve as the industrial standard material as dimensionally stable anodes (DSA). Understanding how the local chemical environment around the active metal sites governs CER kinetics is essential for rational catalyst design. Herein, we employ ab initio molecular dynamics (AIMD) with an explicit liquid–solid interface to investigate the Volmer–Heyrovsky mechanism on the Ru0.5Ti0.5O2(110) surface. The active surface is identified as a fully oxygen-covered configuration, exposing two chemically distinct active sites, i.e., terminal oxygen occupied Ti (Oc_Ti) and Ru (Oc_Ru). The calculated free energy profiles reveal that while the Volmer step proceeds with comparable barriers on both sites, the subsequent Heyrovsky step is significantly favored on the Oc_Ru site over the Oc_Ti site. The Oc_Ru site contributes predominantly to catalytic activity, with the Volmer step serving as the rate-determining step. These findings highlight the essential role of Ru in working as active sites on DSA-type electrodes and demonstrate the importance of explicit solvation in capturing the mechanistic picture of the CER process.