Enhanced low-temperature CO oxidation activity through crystal facet engineering of Pd/CeO2 catalysts

Cerium dioxide (CeO 2 ) supported palladium (Pd) catalysts have found widespread application in CO oxidation reaction owing to their exceptional catalytic performance. The morphology of the CeO 2 support dictates the exposed crystal plane, exerting a profound influence on surface structure and redox properties. This is crucial as the atomic arrangement at the surface directly impacts catalytic activity. In this study, a range of CeO 2 supports with diverse morphologies ( e.g. nano-octahedra, nano-cubes, nano-particles, nano-spheres, and nano-rods) were successfully synthesized through hydrothermal methods and subsequently supported with Pd for CO oxidation. The spherical 1Pd/CeO 2 –S catalyst, revealing exposed (111) + (100) crystal planes, exhibited significantly higher CO catalytic oxidation activity compared to the catalysts with other morphological CeO 2 supports. The results indicated a positive correlation between the content of Pd x Ce 1-x O 2-y species and catalytic activity. Notably, this species was most abundantly formed in the spherical 1Pd/CeO 2 –S catalyst with exposed (111) + (100) crystal planes. The presence of this active species facilitated the formation of surface defects , increased oxygen vacancy concentration, and enhanced metal-support interaction, consequently greatly improving the CO low-temperature catalytic oxidation activity. Consequently, the oxidation state of Pd in the Pd/CeO 2 catalyst could be effectively regulated by controlling the exposure of (111) + (100) crystalline surfaces of the CeO 2 support, further optimizing the catalytic performance of the Pd/CeO 2 catalytic system.