Effective removal of automobile exhausts over flower-like Ce1−xCuxO2 nanocatalysts exposed active {100} plane

Abstract

This work elucidates the synthesis and characterization of copper ions incorporated ceria (Ce1−xCuxO2) nanocatalysts with 3D flower-like and nanocrystalline morphology for the purification of automobile exhausts. XRD and Raman results confirm the presence of copper ions in ceria. The 3D flower-like and nanocrystalline morphology exhibited by these catalysts were seen by FESEM images. HRTEM and SAED results confirm that (100) plane is dominantly presented in 3D flower-like Ce1−xCuxO2 catalysts when compared to nanocrystalline morphology. The textural properties of synthesized catalysts was done with the help of N2 sorption study, which confirms that flower-like Ce1−xCuxO2 catalysts show high surface area and pore volume. The existence of Ce3+, Ce4+, Cu+ and Cu2+ ions in the catalyst were examined by XPS and DR UV–Vis techniques. Oxygen storage capacity (OSC) of the catalysts was studied by H2-TPR analysis. These characterization results elucidate the presence of dominant active sites (Ce3+, Ce4+, Cu+ and Cu2+) and {100} plane in the flower-like morphology compared to nanocrystalline. The catalytic activity of synthesized Ce1−xCuxO2 catalysts was tested for removal of CO, HCx and NO gases from automobile emission with respect to the copper content and morphology. The obtained results indicate that the presence of optimum amount of copper in ceria with flower-like morphology is essential for the removal of CO, HCx and NO at low temperature via redox process, which is due to the presence of active sites on the dominant {100} plane.