Controlled synthesis of CeO2 nanorods and their promotional effect on catalytic activity and aging resistibility for diesel soot oxidation

Nanostructure of catalysts plays a critical role in catalytic activity and durability. Herein, a ceria nanorod catalyst, CeO₂(NR), was designed and synthesized, and the relationships between nanostructure and catalytic activity as well as aging resistibility were investigated. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction results indicate that the nanorod structure of CeO₂(NR) can be well maintained after aging at 900 °C for 8 h and can prevent the excessive expansion of crystals during high-temperature aging. X-ray photoelectron spectroscopy and hydrogen temperature-programmed reduction results suggest that the CeO₂(NR) nanorod has distinctly more oxygen vacancies than the CeO₂ nanoparticle; moreover the nanorod structure of CeO₂(NR) and CeO₂(NR)-A can enhance the lattice oxygen mobility and contribute to the spillover of lattice oxygen to form surface active oxygen during high temperature reaction. Finally, the catalytic activity tests indicate that the synthesized CeO₂(NR) nanorod catalyst displays significantly better soot purification efficiency and intrinsic activity for soot oxidation; more than that, this superior catalytic activity of CeO₂(NR) is well maintained after high-temperature thermal aging. Thus, this work suggests that the nanorod structure of ceria-based catalysts plays a key role in enhancing aging resistibility and catalytic soot oxidation activity.