J. Walter et al., Ultrathin platinum nanoparticles encapsulated in a graphite lattice-prepared by a sonochemical approach, CHEM MATER, 13(5), 2001, pp. 1828-1833
H2PtCl6 was intercalated into natural graphite by applying ultrasound to a
mixture of graphite, H2PtCl6, CCl4, and SOCl2 for 3 days. X-ray diffraction
data showed that the host lattice was partly intercalated by H2PtCl6. A mi
xture consisting of a third and fourth stage together with unreacted graphi
te was observed. The intercalation compound was suspended in acetone with h
ydrogen flowing through while the sonication took place for 2 days. Transmi
ssion electron microphotographs showed highly dispersed nanoparticles in a
narrow size range inside the carbon lattice. X-ray photoelectron spectrosco
py gave evidence that these particles are platinum metal (Pt-0). Particle t
hickness estimated by X-ray diffraction indicated an average particle thick
ness of two layers. Selected-area electron diffraction microphotographs sho
wed a pattern that could be hexagonally indexed. A (2 x alpha (graphite)) s
uperstructure was observed for those quasi-two-dimensional aggregates forme
d by self-organization. This indicates a templating effect due to the carbo
n lattice.