Shape-Selective Synthesis and Oxygen Storage Behavior of Ceria Nanopolyhedra, Nanorods, and Nanocubes

Abstract

Single-crystalline and uniform nanopolyhedra, nanorods, and nanocubes of cubic CeO2 were selectively prepared by a hydrothermal method at temperatures in the range of 100-180 degrees C under different NaOH concentrations, using Ce(NO3)3 as the cerium source. According to high-resolution transmission electron microscopy, they have different exposed crystal planes: {111} and {100} for polyhedra, {110} and {100} for rods, and {100} for cubes. During the synthesis, the formation of hexagonal Ce(OH)3 intermediate species and their transformation into CeO2 at elevated temperature, together with the base concentration, have been demonstrated as the key factors responsible for the shape evolution. Oxygen storage capacity (OSC) measurements at 400 degrees C revealed that the oxygen storage takes place both at the surface and in the bulk for the as-obtained CeO2 nanorods and nanocubes, but is restricted at the surface for the nanopolyhedra just like the bulk one, because the {100}/{110}-dominated surface structures are more reactive for CO oxidation than the {111}-dominated one. This result suggests that high OSC materials might be designed and obtained by shape-selective synthetic strategy.

CuO-CeO2 supported on montmorillonite-derived porous clay heterostructures (PCH) for preferential CO oxidation in H2-rich stream

“…Data included in Table 3 show that all catalysts show a I sat /I mp value lower than that normally observed for CuO (0.55), indicating the presence of partially reduced copper species [60,61] but in the case of samples with 12 wt% of copper a very low reduction degree of Cu 2+ is observed and the found I sat /I mp values are very close to that of CuO, corroborating XRD and TPR results.…”

Ceria‐Based Solid Catalysts for Organic Chemistry

“…The great variety of cerium-based mixed oxides allows to adjust acid-base and redox properties and to modulate both the number and strength of active sites for the desired reaction. New developments in the synthesis of ceria nanocrystals of controlled shapes (nanorods, nanocubes, polyhedras, and others) [268,269] should also lead to new catalysts with higher activities and selectivities in organic chemistry and catalysis. …”

Gd–Bi–Ce–O materials as catalysts in CO oxidation

“…This leads to the relative stability of the low index ceria surfaces following the trend: (111) [ (110) [ (100), but the formation energies of oxygen vacancies on different planes of ceria vary, following the order: (110) \ (100) \ (111), and the frequency of use of crystalline planes has the order: (100) \ (110) \ (111). So, the higher catalytic activity is due to the exposed (100) and (110) planes (form of particles: spindle-shaped, rods, cubes), but ceria nanoparticles preferentially expose stable (111) planes (Wu et al 2012;Lawrence et al 2011;Na et al 2008;Mai et al 2005;Lundberg et al 2004;Sayle et al 2002). FTIR spectra (Fig.…”