Electronic Interactions in the Rhodium/TiO sub 2 System

摘要

A variety of electron spectroscopic techniques have been used with model catalysts fabricated on single-crystal substrates to study charge transfer in the Rh/TiO/sub 2/ system. In order to avoid the morphological changes and encapsulation that occur when catalysts are reduced at high temperatures to induce SMSI (strong metal-support-interactrons), TiO sub 2 substrates have been reduced by inert gas ion bombardment prior to Rh deposition. Comparison of model catalysts prepared on reduced supports with those prepared on fully oxidized supports indicate that electronic charge is transferred from reduced Ti cations to Rh particles, resulting in a partially ionic Rh-Ti bond. The Rh-Ti bonding may provide a driving force for menencapsulation of the Rh but does not lead to a large scale suppression of the capacity of the Rh to chemisorb CO. We also present the first direct evidence for modification of the valence levels of the Rh due to the presence of the encapsulating Ti suboxide moieties during SMSI. 39 refs., 9 figs. (ERA citation 13:018546)