Adsorption of Imidazolium-Based Ionic Liquid On Pt(111) Surface Studied Using Density Functional Theory

The strength and nature of adsorption of imidazolium-based tetraflouroborate ionic liquid (IL) on platinum surface has been investigated via first principle-based density functional theory method. Adsorption of both IL cation and IL ion-pair as a function of increasing alkyl chain length is taken into consideration. Three different orientations of ionic liquid cations are found to be stable with higher adsorption energy noticed for the alkyl chain parallel to the platinum surface. The anions are found to stabilize the IL cation orientation where the alkyl chain is oriented perpendicular the platinum surface. These results are further corroborated by the charge transfer analysis and electron density difference maps. The significant charge transfer between the ionic liquid pair and the surface indicates electrochemical applications for systems involving electrolytes and metal surface, where electrostatic interactions play a major role. The results of this investigation can be helpful for further analysis of electrode–electrolyte systems as well as the development of force field parameters for these systems.