Interactions between 1‐butyl‐3‐methylimidazolium tetrafluoroborate ionic liquid and γ‐Al₂O₃(100) surface calculated by density functional theory

Abstract

Abstract The main aim of this work is to investigate the 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([C 4 C 1 Im] + [BF 4 ] − ) ionic liquid (IL) adsorption on the γ‐Al 2 O 3 (100) by density functional theory calculations to try to rationalize the adsorption as an electrostatic phenomenon. Optimized geometries and interaction energies of IL one‐monolayer on the γ‐Al 2 O 3 were obtained on high surface coverage (one cation–anion pair per 94.96 nm 2 ). A study of dispersion force was made to estimate its contribution to the adsorption. Overall, the process is ruled by electrostatic interaction between ions and surface. Adsorption of the anion [BF 4 ] − and cation [C 4 C 1 Im] + was also studied by Bader charge analysis and charge density difference for supported and unsupported situations. It is suggested that the IL ions have their charges maintained with significant anion cloud polarization inward to the acid aluminum sites. © 2012 Wiley Periodicals, Inc.