Adsorption of Water Molecules on Metal Surface: A DFT Study

Abstract

The investigation of water molecule(s) adsorption on metal surfaces plays a vital role in material sciences and various energy applications [1]. Further, to solve the challenging questions in biology and chemistry province, the study of metal-water interfaces is essential [2-4]. The structure of water clusters (i.e. (H₂O)_n) at a hydrophobic/-hydrophilic interface is completely different from the aqueous environment [5,6]. The contemporary topic of research is to study the effect of metal surfaces on the structure and stability of water molecule(s) in the first layer. In this study, we made an effort to identify the catalytic role of Cu₂₀ nanoclusters and Cu(111) surface which induces the structure and stability of water molecules using the first principle approach (Fig.1). Our calculations suggest that the structure of water clusters directly depends on the nature of the hydrogen bond (water - water) and binding strength of metal(M)-water(W) interactions (i.e. OH/H₂O). It is found that on the metal surface some of the conformations of adsorbed most stable water clusters are converted into other isomers. This conformational change is due to the intermolecular interaction between water molecules and metal surfaces. It is significant to note that this interfacial interaction and hydrogen bond are responsible for the water clusters stability on the metal surface. In addition, to understand the interfacial interaction, cooperative effect, and bonding nature of these clusters were investigated by noncovalent index (NCI) and molecule electrostatic potential analysis (MESP). Additionally, to get more insights on the structure, stability, and vibration spectra of (H₂O)_n@Cu (where n = 1 – 6) surface (both cluster and surface models) were studied by density functional theory (DFT) approach.