Growth and properties of small Rh particles within an NaX matrix. Thermal analysis, electron microscopy, IR and photoelectron spectroscopy
- 1 January 1996
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions
- Vol. 92 (4) , 693-700
- https://doi.org/10.1039/ft9969200693
Abstract
Rhodium dispersions with different distinct average particle sizes, ranging from 1–2 to 6 nm, are prepared in zeolite NaX from Rh complexes ion exchanged with constant degrees of exchange and autoreduced by temperature-programmed decomposition. Thermal analysis and photoelectron spectroscopy demonstrate different elementary steps of Rh precipitation starting from either chlorine-free or chlorine-containing complexes. The stabilization of the Rh+ state for the chlorine-free sample is concluded from photoelectron spectra of Rh 3d5/2 and confirmed by IR spectra using the probe carbon monoxide. Different average sizes of Rh particles are evaluated from electron micrographs with standard deviations of 10–20%. The shifts of the electron binding energies in core level Rh 3d5/2 and valence-band spectra agree with theoretical predictions for intrinsic particle-size effects and indicate a low contribution of the relaxation effect.Keywords
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