EFFECTS OF ALTERVALENT CATION DOPING OF TIO2, ON H-2, AND CO ADSORPTION ON SUPPORTED RH

The influence of W6+-doping of TiO2 carriers on the mode of H2 and CO adsorption on Rh crystallites dispersed on their surfaces is investigated. It is shown that the electrical conductivity of W6+-doped TiO2 is enhanced while the activation energy of electron conduction is reduced. The capacity of Rh to adsorb H2 at equilibrium is found to increase monotonically with increasing W6+-dopant concentration in the carrier, while the strength of the adsorption bond is not significantly affected. The capacity of Rh to adsorb CO goes through a maximum at a W6+-dopant concentration of 0.22 atom% in the TiO2 matrix. The strength of the CO adsorption bond is weakened when Rh is dispersed on doped TiO2. These phenomena are attributed to long-range electronic interactions at the metal-support interface which alter the work function of surface metal atoms, as well as to short-range electronic interactions at the gas-metal-support interface. © 1994 Academic Press, Inc.