Surface-Dependence of Defect Chemistry of Nanostructured Ceria

Abstract

The defect chemistry of reduced ceria nanoshapes was investigated using in situ Raman and FTIR spectroscopy. Octahedral- and rod-shaped particles behave similarly upon exposure to CO in terms of formation of anion Frenkel pair defects and oxygen vacancies. This similarity is attributed to the preferential exposure of (111) surfaces in both type of particles. Cube-shaped particles terminated with (100)-oriented surfaces exhibit very different defect behavior in CO, revealing formation of oxygen vacancy defects at the expense of existing anion Frenkel pairs. Octahedra and rods, prereduced in H2, can be further reduced with CO. In contrast, prereduced cubes can reactively adsorb CO, forming surface-bicarbonate, only via converting Frenkel-pair defects to oxygen vacancies, without any further net reduction of the ceria.

Direct Phenolysis Reactions of Unactivated Amides into Phenolic Esters Promoted by a Heterogeneous CeO2 Catalyst

“…This catalytic system not only offers a facile means to cleave the amide C−N bond, but also significantly promotes the use of amides and phenols as important building blocks for the synthesis of valuable esters. Moreover, the obtained results provide a better understanding of the catalytic behavior of CeO 2 , which has been of significant interest recently …”

Water‐Gas‐Shift over Metal‐Free Nanocrystalline Ceria: An Experimental and Theoretical Study

“…The metals adsorb and activate CO, while the ceria serves to dissociate water . Nanostructured “metal‐free” ceria, especially sub‐10 nm nanoparticles, has recently become an interest for fundamental studies of the water‐gas shift reaction over the oxide . Herein we present a combined experimental and theoretical study of ceria in the WGS reaction, suggesting that the degree of surface reduction, specifically on the (1 0 0) facet exposed on ceria nanoparticles, has a major effect on the native activity of metal‐free ceria.…”

Pure and Fe-doped CeO2 nanoparticles obtained by microwave assisted combustion synthesis: Physico-chemical properties ruling their catalytic activity towards CO oxidation and soot combustion

“…The nature of surface species can be studied through adsorption of probe molecules as followed by IR spectroscopy, which is a fundamental technique for the study of surface species [58][59][60], like the different types of OH groups [16,61,62] usually found at the surface of ceria and depicted in Scheme 1. Figure 6 reports the IR spectra of the CeO2 sample pretreated as follows: outgassed at 250 °C (curve a), oxidized at 400 °C (curve b) and then reduced in H2 at 200 °C (curve c).…”

“…a surfactant as organic template). Changes in morphology affect the surface properties of CeO2 NPs, the defects chemistry of the material and the related catalytic activity, especially as far as CeO2 reducibility is concerned [16].…”