Effect of the exposed ceria morphology on the catalytic activity of gold/ceria catalysts for the preferential oxidation of carbon monoxide

Ceria (CeO₂) with different crystal-planes were used as supports to synthesize gold (Au)/CeO₂ catalysts for the preferential oxidation of carbon monoxide (CO). A CeO₂ morphology-dependent Au-CeO₂ interaction was observed. Au/CeO₂-R in this present work performed the outstanding activity at lower temperature than ever since other works were reported. The Au catalyst supported on rod-shaped CeO₂ exhibited the highest CO conversion level of 97.9% at 30 °C, followed by that on polyhedral- (94.0%), cube- (74.0%) and octahedral- (27.7%) shaped CeO₂. The catalytic activities were strongly affected by the CeO₂ crystal-planes and Au active species. The rod-shaped CeO₂ enclosed by (1 1 0) and (1 0 0) planes might interact strongly with Au species, generating the most accessible active sites to absorb/desorb and activate the CO and oxygen molecules. The octahedral-shaped CeO₂ enclosed by the (1 1 1) plane had the lowest catalytic activity since the (1 1 1) plane is the most stable and irreducible of the CeO₂ (1 1 1), (1 0 0) and (1 1 0) planes, accounting for its decreased catalytic activity.