First-principle investigation of the interactions between PtxRu55-x (x=0, 13, 42, 55) nanoparticles and [BMIM][PF6] ionic liquid

Density functional theory calculations have been performed to characterize the interactions between [BMIM][PF6] ionic liquid and icosahedral PtxRu55-x (x = 0, 13, 42, 55) nanoparticles. In Ru13Pt42-[BMIM][PF6], only one F atom of the anion form the bond with nanoparticle, resulting in the smallest interaction energy (-0.56 eV). While in Pt13Ru42-[BMIM][PF6], two F atoms of the anion together with two C atoms of cation form the bonds with nanoparticle, resulting in the biggest interaction energy (-10.65 eV). The interaction between [BMIM][PF6] and Pt13Ru42 is so strong that it induces a significant distortion in the original core-shell structure of Pt13Ru42. Moreover, after interacting with [BMIM][PF6], the Pt-55, Pt13Ru42 and Ru-55 nanoparticles become more stable based on the negative relaxation energy. The d-band centers of Pt13Ru42 and Ru-55 shift from -1.90, -1.78 eV up to -1.78, -1.56 eV, suggesting that the catalytic activities of Pt13Ru42 and Ru-55 are enhanced. (C) 2015 Elsevier B.V. All rights reserved.