Ultrathin Platinum Nanoparticles Encapsulated in a Graphite LatticePrepared by a Sonochemical Approach

H 2 PtCl 6 was intercalated into natural graphite by applying ultrasound to a mixture of graphite, H 2 PtCl 6, CCl 4, and SOCl 2 for 3 days. X-ray diffraction data showed that the host lattice was partly intercalated by H 2 PtCl 6 . A mixture consisting of a third and fourth stage together with unreacted graphite was observed. The intercalation compound was suspended in acetone with hydrogen flowing through while the sonication took place for 2 days. Transmission electron microphotographs showed highly dispersed nanoparticles in a narrow size range inside the carbon lattice. X-ray photoelectron spectroscopy gave evidence that these particles are platinum metal (Pt 0 ). Particle thickness estimated by X-ray diffraction indicated an average particle thickness of two layers. Selected-area electron diffraction microphotographs showed a pattern that could be hexagonally indexed. A (2 × a graphite ) superstructure was observed for those quasi-two-dimensional aggregates formed by self-organization. This indicates a templating effect due to the carbon lattice.