文摘
[Bmim]2PtCl4 (Bmim: 1-butyl-3-methylimidazolium) ionic liquid was confined in porous SiO2 nanoparticles ([Bmim]2PtCl4@SiO2) with an average pore size of 7.1 nm. The structure of [Bmim]2PtCl4@SiO2 was investigated through X-ray diffraction and X-ray absorption fine structure (XAFS). The average coordination numbers of Pt species in [Bmim]2PtCl4 and [Bmim]2PtCl4@SiO2 were 4.0 and 5.0, respectively. Parts of Pt2+ in [Bmim]2PtCl4@SiO2 were oxidized to form high-valence Pt4+. The possible forms and structures of Pt in the ionic liquid were analyzed according to the coordination number. XAFS analysis and density functional theory calculations imply the favorable formation of dimer (i.e., Pt2Cl82鈥?/sup>) in [Bmim]2PtCl4@SiO2, in which two bridge Cl atoms were connected to two Pt atoms. In addition, Pt2Cl82鈥?/sup> contained mixed-valence platinum (Pt2+ and Pt4+). The results of differential scanning calorimetry also showed that the melting point of this nanoconfined ionic liquid increased.