Entropy governs the structure and reactivity of water dissociation under electric fields

Abstract

The response of water to electric fields is critical to the performance and stability of electrochemical devices, and the selectivity of enzymatic, atmospheric, and organic reactions. A key process in this context is the water (auto)dissociation reaction (WD), which governs acid-base aqueous chemistry and shapes reaction rates and mechanisms. Despite its significance, the thermodynamics of the WD reaction in electrified environments remains poorly understood. Here, we investigate the WD reaction under external electric fields using ab initio molecular dynamics simulations within the framework of the modern theory of polarization. Our results reveal that strong electric fields dramatically enhance the WD reaction, increasing the equilibrium constant by several orders of magnitude. Moreover, we show that the applied field transforms the WD reaction from an entropically hindered process to an entropy-driven one. Analysis shows that this is because the electric field alters the tendency of ions to be structure makers or structure breakers. By highlighting how strong electric fields reshape solvent organization and reactivity, this work opens new avenues for designing aqueous electro-catalysts that leverage solvent entropy to enhance their performance.

References in corpus (11)

• Canonical sampling through velocity-rescaling
• Ab initio molecular dynamics study of dissociation of water under an electric field
• Self-Consistent Determination of Long-Range Electrostatics in Neural Network Potentials
• i-PI 3.0: a flexible and efficient framework for advanced atomistic simulations
• Wien effect in interfacial water dissociation through proton-permeable graphene electrodes
• Molecular dynamics simulation with finite electric fields using Perturbed Neural Network Potentials
• Developing machine-learned potentials to simultaneously capture the dynamics of excess protons and hydroxide ions in classical and path integral simulations
• Mechanistic insights into water autoionization
• Effect of entropy on the nucleation of cavitation bubbles in water under tension
• How reactive is water at the nanoscale and how to control it?
• Electric-Field Driven Nuclear Dynamics of Liquids and Solids from a Multi-Valued Machine-Learned Dipolar Model