TiO2 morphology has an important effect on the activity and stability of the noble metals for CO oxidation. Here, hierarchical TiO2 microspheres of about 2.2 μm in diameter with a localized nanosheet about 23.2 nm in thickness, were prepared and used as a support for Pd catalyst. Various characterization methods including TEM, SEM, N2 adsorption, XPS, CO-DRIFTS, CO pulse chemisorption, CO-TPD, O2-TPD, and ICP were used in this study. As compared with commercial TiO2, the special nanosheet assemblied structure of TiO2 with larger surface areas led to higher dispersed Pd species, stronger Pd–TiO2 interaction, and enhanced CO and O2 adsorption, ultimately leading to better catalytic activity and stability. Among the three catalysts of Pd/TiO2-350, Pd/TiO2-P25, and Pd/TiO2-CA, the corresponding 100% conversion temperatures were 80, 140, and 160 °C, respectively. The CO conversion on Pd/TiO2-350 remained stable over 22 h. On the contrary, the Pd/TiO2-P25 catalyst suffered rapid deactivation with time on stream.
