Vibrational properties of water-metal interfaces under a bias potential*

The interest in renewable sources of energy has demanded a deeper understanding of the electrochemical process since it is one of the pillars of green energy sources. Consequently, first principles computer simulations, notably Density Functional Theory (DFT) ones, have provided crucial insights into the molecular and electronic structure of water-metal interfaces, dealing with charge and energy transfer reactions, adsorption, and heterogeneous catalysis. Despite these recent developments, the atomistic description of the structural and vibrational properties of the water-metal interface under an applied bias potential is still a challenge. Furthermore, experimental results showing the potential-dependent structure of the interfacial water have motivated first-principle calculations studies of hydrogen bond, and water-metal interaction under an external bias potential. 

In this work, we have combined DFT and non-equilibrium Green's function (NEGF) methods to properly compute the effect of an external bias potential applied to Au(111) and Pd(111) metallic electrodes. With this setup, we investigated the effect of this non-equilibrium situation on the structural, dynamical, and vibrational behavior of water adsorbed on these metallic interfaces.