Abstract
Ceria-based mixed oxides have been widely studied in catalysis due to their unique surface and redox properties, with implications in numerous energy- and environmental-related applications. In this regard, the rational design of ceria-based composites by means of advanced synthetic routes has gained particular attention. In the present work, ceria–titania composites were synthesized by four different methods (precipitation, hydrothermal in one and two steps, Stöber) and their effect on the physicochemical characteristics and the CO oxidation performance was investigated. A thorough characterization study, including N2 adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM) and H2 temperature-programmed reduction (H2-TPR) was performed. Ceria–titania samples prepared by the Stöber method, exhibited the optimum CO oxidation performance, followed by samples prepared by the hydrothermal method in one step, whereas the precipitation method led to almost inactive oxides. CeO2/TiO2 samples synthesized by the Stöber method display a rod-like morphology of ceria nanoparticles with a uniform distribution of TiO2, leading to enhanced reducibility and oxygen storage capacity (OSC). A linear relationship was disclosed among the catalytic performance of the samples prepared by different methods and the abundance of reducible oxygen species.
Highlights
Ceria (CeO2 ) has attracted significant attention in heterogeneous catalysis due to its enhanced properties such as high oxygen storage capacity (OSC) and thermal stability, [1,2,3]
The bare ceria nanorods (CeO2 -NRs) and ceria–titania prepared by the one-step hydrothermal method (CeO2 /TiO2 -H1) exhibit similar catalytic behaviour but, in both cases, their profiles are shifted by approximately 30 degrees to higher temperature than CeO2 /TiO2 -S
Ceria–titania mixed oxides were prepared by the hydrothermal, Stöber and precipitation methods
Summary
Ceria (CeO2 ) has attracted significant attention in heterogeneous catalysis due to its enhanced properties such as high oxygen storage capacity (OSC) and thermal stability, [1,2,3]. Ceria-based metal oxides are extensively investigated in heterogeneous catalysis as supporting carriers or catalysts by themselves due to their surface and structural features which are totally different from those of parent oxides [2,3,12,13,14,15,16,17,18,19,20,21,22,23]. The incorporation of various transition metals into the ceria carrier can lead to significant physicochemical perturbations through the geometric and/or electronic interactions developed between the different counterparts [2,24,25,26,27,28]
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