Bias-dependent local structure of water molecules at a metallic interface.

Chem Sci

Department of Physics and Astronomy , Stony Brook University, Stony Brook , New York 11794-3800 , USA.

Published: January 2018

AI Article Synopsis

  • Understanding the local structure of water at metallic electrode interfaces is crucial for aqueous electrochemistry but challenging to simulate, especially under varying potentials.
  • The study combines Density Functional Theory (DFT) and Non-Equilibrium Green's Function (NEGF) methods to effectively calculate forces and dynamics at these electrodes, linking them to the chemical potential measured in experiments.
  • Findings reveal that water molecules align their dipole moments with the electric field and their interaction with the metal surface varies based on the sign and strength of the applied bias potential, exhibiting asymmetric behavior.

Article Abstract

Understanding the local structure of water at the interfaces of metallic electrodes is a key issue in aqueous-based electrochemistry. Nevertheless a realistic simulation of such a setup is challenging, particularly when the electrodes are maintained at different potentials. To correctly compute the effect of an external bias potential applied to truly semi-infinite surfaces, we combine Density Functional Theory (DFT) and Non-Equilibrium Green's Function (NEGF) methods. This framework allows for the out-of-equilibrium calculation of forces and dynamics, and directly correlates to the chemical potential of the electrodes, which is introduced experimentally. In this work, we apply this methodology to study the electronic properties and atomic forces of a water molecule at the interface of a gold surface. We find that the water molecule tends to align its dipole moment with the electric field, and it is either repelled or attracted to the metal depending on the sign and magnitude of the applied bias, in an asymmetric fashion.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5869310PMC
http://dx.doi.org/10.1039/c7sc02208eDOI Listing

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