Interaction of CO2 with metal cluster-functionalized ionic liquids

Metal cluster-functionalized ionic liquids (ILs) exhibit promising characteristics for CO2 conversion, however, progress in this area is currently limited due to the lack of understanding of the underlying reaction mechanisms involved. In this article the interaction of CO2 with metal cluster-functionalized ILs is studied and provides key insights into the initial stages of CO2 activation and subsequent conversion. The interaction of CO2 with Au-Pd cluster-functionalized ILs is investigated using density functional theory (DFT) calculations based on the DFT-B3LYP approach and the mixed basis sets of 6-31+G (d, p) and LANL2DZ. It is found that single Au or Pd atoms can interact with ILs and results in a significantly stronger interaction of Au with ILs than that of Pd. More broadly it is also found that Au-Pd cluster-functionalized ILs can significantly enhance the interaction of CO2 with ILs. Interestingly the interaction of CO2 with Au-Pd cluster-functionalized IL is found to be highly dependent on the size and composition of the cluster. Among the systems studied, Au1Pd2-functionalized IL yields the strongest interaction with CO2. Our results highlight a non-monotonous behavior for the composition- and size-dependent interaction of CO2 with Au-Pd cluster-functionalized ILs. It is proposed that these findings can provide a new roadmap for the design and development of metal cluster-functionalized ILs for CO2 conversion applications. (C) 2016 Elsevier Ltd. All rights reserved.