Carbon dioxide adsorption and activation on ionic liquid decorated Au(111) surface: A DFT study

We use first principle approaches to study the adsorption and catalytic activation mechanism of CO2 on ionic liquids (ILs, [CnMIm]+[Cl]- (n = 0–6)) attached to a Au(111) surface. The adsorption of CO2 at this liquid-solid model interface occurs via either (i) parallel π-stacking mode or (ii) CO2 oxygen lone pair (lp)···π interaction. These CO2 physisorption modes, which depend on the CO2 landing angle at this interface, are identified as an efficient way to activate CO2 and its further conversion into value-added products. For illustration, we discuss the conversion of CO2 into formic acid where the ILs@Au(111) decorated interface allows reduction of the activation energy for the CO2 + H2 → HCOOH reaction. In sum, our electrode/electrolyte based interface model provides valuable information to design novel heterogeneous catalysts for CO2 conversion. Indeed, our work establishes that a suitable interface material is enough to activate CO2. [Display omitted] •The adsorption mechanisms of CO2 at gas phase and solid-liquid interface are studied.•The adsorption strength of CO2 molecule at ILs@Au(111) interface depends strongly on the alkyl chain length.•The mode of adsorption mechanisms and CO2 landing sites were identified.•CO2 is successfully activated and converted at the ILs@Au(111) surface.