The comparative catalytic activity and coke resistance are examined in carbon dioxide reforming of methane over Ni/CeO 2 nanorods (NR) and nanopolyhedra (NP). The Ni/CeO 2 −NR catalysts display more excellent catalytic activity and higher coke resistance compared with the Ni/CeO 2 −NP. The high resolution transmission electron microscope reveals that the predominantly exposed planes are the unusually reactive {110} and {100} planes on the CeO 2 − NR rather than the stable {111} one on the CeO 2 −NP. The prepared samples were also characterized by X-ray diffraction, transmission electron microscopy, hydrogen temperature-programmed reduction, X-ray photoelectron spectroscopy, UV and visible Raman spectra, and oxygen temperature-programmed oxidation. The {110} and {100} planes show great superiority for the anchoring of Ni nanoparticles, which results in the existence of strong metal−support interaction effect (SMSI). The SMSI effect can be helpful to prevent sintering of Ni particles, which benefits to reduce the deactivation of catalytic activity. Besides, the oxygen vacancies and the mobility of lattice oxygen also show the morphology dependence. They can participate into the catalytic reaction and be beneficial to the activation of carbon deposition. In conclusion, the excellent catalytic activity and coke resistance of the Ni/CeO 2 −NR should be attributed to the SMSI effect and abundant oxygen vacancies.

Herein, we have rationally designed and originally developed a high-performance deNO x catalyst based on hollow porous Mn x Co 3−x O 4 nanocages with a spinel structure thermally derived from nanocube-like metal−organic frameworks (Mn 3 [Co(CN) 6 ] 2 •nH 2 O), which are synthesized via a self-assemble method. The as-prepared catalysts have been characterized systematically to elucidate their morphological structure and surface properties. As compared with conventional Mn x Co 3−x O 4 nanoparticles, Mn x Co 3−x O 4 nanocages possess a much better catalytic activity at low-temperature regions, higher N 2 selectivity, more extensive operating-temperature window, higher stability, and SO 2 tolerance. The feature of hollow and porous structures provides a larger surface area and more active sites to adsorb and activate reaction gases, resulting in the high catalytic activity. Moreover, the uniform distribution and strong interaction of manganese and cobalt oxide species not only enhance the catalytic cycle but also inhibit the formation of manganese sulfate, resulting in high catalytic cycle stability and good SO 2 tolerance. In light of the various characterization results, the excellent deNO x performance of Mn x Co 3−x O 4 nanocages can be attributed to the hollow and porous structures, the uniform distribution of active sites, as well as the strong interaction of manganese and cobalt oxide species. The excellent catalytic performance suggests that Mn x Co 3−x O 4 nanocages are promising candidates for low-temperature deNO x catalysts. More importantly, the present study indicates that the hollow porous architectures and well-dispersed active components can effectively enhance the performance of catalysts.

Because of their excellent properties and extensive applications, ceria nanomaterials have attracted much attention in recent years. This perspective provides a comprehensive review of current research activities that focus on the shape-controlled synthesis methods of ceria nanostructures. We elaborate on the synthesis strategies in the following four sections: (i) oriented growth directed by the crystallographic structure of cerium-based materials; (ii) oriented growth directed by the use of an appropriate capping reagent; (iii) growth confined or dictated by various templates; (iv) other potential methods for generating CeO(2) nanomaterials. In this perspective, we also discuss the catalytic applications of ceria nanostructures. They are often used as active components or supports in many catalytic reactions and their catalytic activities show morphology dependence. We review the morphology dependence of their catalytic performances in carbon monoxide oxidation, water-gas shift, nitric oxide reduction, and reforming reactions. At the end of this review, we give a personal perspective on the probable challenges and developments of the controllable synthesis of CeO(2) nanomaterials and their catalytic applications.

The MnO(x) and CeO(x) were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH(3). X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H(2) temperature-programmed reduction (H(2)-TPR) and NH(3) temperature-programmed desorption (NH(3)-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H(2)-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH(3)-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO(2)-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods.