Creation of Redox Adsorption Sites by Pd2+Ion Substitution in nanoTiO2for High Photocatalytic Activity of CO Oxidation, NO Reduction, and NO Decomposition

The present study aims at developing a new photocatalyst for NO reduction and CO oxidation by creating redox adsorption sites and utilizing oxide ion vacancy in titania. For this purpose, Pd ion-substituted TiO 2, Ti 1- x Pd x O 2- δ, was synthesized for the first time by solution combustion method. The photocatalytic activity was investigated with increasing Pd substitution and the optimum concentration was found to be 1 atom % Pd ion in TiO 2 . The reduction of NO was carried out both in the presence and in the absence of CO. Despite competitive adsorption of NO and CO on the Pd 2+ sites, the reduction of NO was 2 orders of magnitude higher than unsubstituted TiO 2 . High rates of photooxidation of CO with O 2 over Ti 1- x Pd x O 2- δ are observed at room temperature. It was shown that enhanced CO oxidation at Pd 2+ ion site and O 2 or NO photo dissociation at oxide ion vacancy is responsible for the enhanced catalytic activity.