Electric-field induced entropic effects in liquid water

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Electric fields influence aqueous systems, impacting electrochemistry and hydrogen technologies.
• Thermodynamics of electric fields in water are partially understood, but entropy effects remain largely unexplored.

Purpose of the Study:

• To investigate the impact of electric fields on the total and local entropy of bulk water.
• To quantify field-induced entropic changes using molecular dynamics simulations.
• To develop a method for spatially resolving local entropy and density changes.

Main Methods:

• Classical (TIP4P/2005) and ab initio molecular dynamics simulations were employed.
• Simulations measured entropic contributions under various electric field intensities.
• A novel 3D-2PT analysis was developed to map local entropy and number density.

Main Results:

• Strong electric fields align water molecular dipoles, but result in modest entropy reductions in classical simulations.
• First-principles simulations showed more significant entropy variations, yet still small compared to freezing.
• The study found that electrofreezing is improbable in bulk water at room temperature.

Conclusions:

• Electric fields induce minor entropy changes in liquid water, insufficient for room-temperature electrofreezing.
• The developed 3D-2PT method provides atomistic resolution for mapping local entropic and structural changes.
• Findings contribute to understanding water's response to electric fields in electrochemical and hydrogen technologies.