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The development of an efficient doped CeO2 material is an active area of intense research in environmental catalysis. In this study, we prepared highly promising Ce–Fe nano-oxides by a facile coprecipitation method and their catalytic performance was studied for CO oxidation. Various characterization techniques, namely, XRD, BET surface area, pore size distribution, Raman, FT-IR, TEM, H2-TPR, and XPS were used to correlate the structure–activity properties of the Ce–Fe catalysts. XRD results confirmed the formation of nanocrystalline Ce1−xFexO2−δ solid solution due to doping of Fe3+ into the CeO2 lattice. The BET surface area and lattice strain of CeO2 are significantly improved after the Fe-incorporation. Raman studies revealed the presence of abundant oxygen vacancies in the Ce–Fe sample. TEM images evidenced the formation of nanosized particles with an average diameter of 5–20 nm in the prepared samples. Interestingly, despite the thermal treatment at higher temperatures, the Ce–Fe sample showed remarkable reducible nature compared to pure CeO2 ascribed to existence of strong interaction between the CeO2 and FeOx. The synthesized Ce–Fe nano-oxides calcined at 773 K exhibited excellent CO oxidation performance (T50 = 480 K), with a huge difference of 131 K with respect to pure CeO2 (T50 = 611 K). The outstanding activity of the Ce–Fe catalyst is mainly due to smaller crystallite size, facile reduction, enhanced lattice strain, and ample oxygen vacancies. The superior CO oxidation performance of Ce–Fe nano-oxides with the advantages of low cost and easy availability could make them potential alternatives to noble metal-based oxidation catalysts.

A nanosized Ce–Sm/SiO2 catalyst was found to show an outstanding performance in the oxidation of benzylamines into valuable dibenzylimine products with almost 100% selectivity with O2 as the green oxidant under solvent-free conditions, which is attributed to the presence of abundant strong acidic sites, enhanced oxygen vacancy concentration, and superior BET surface area.

In this work, we systematically investigated the structure–activity performance of nanosized Au/CeO2 and Au/Ce0.9Fe0.1O2−δ catalysts, along with nanocrystalline CeO2 and Ce0.9Fe0.1O2−δ supports, for the oxidation of carbon monoxide and benzylamine. An extensive physicochemical characterization was undertaken using XRD, BET surface area, BJH analysis, TG-DTA, XPS, TEM, Raman, AAS and CHN analyses. XRD studies confirmed the formation of smaller sized Ce0.9Fe0.1O2−δ nanocrystallites due to the incorporation of Fe3+ ions into the CeO2 lattice. Interestingly, Raman analysis revealed that the addition of Au remarkably improves the structural properties of the supports, evidenced by F2g peak shift and peak broadening, a significant observation in the present work. TEM images revealed the formation of smaller Au particles for Au/Ce0.9Fe0.1O2−δ (∼3.6 nm) compared with Au/CeO2 (∼5.3 nm), attributed to ample oxygen vacancies present on the Ce0.9Fe0.1O2−δ surface. XPS studies indicated that Au and Fe are present in metallic and +3 oxidation states, respectively, whereas Ce is present in both +4 and +3 oxidation states (confirming its redox nature). Activity results showed that the incorporation of Fe outstandingly enhances the efficacy of the Au/CeO2 catalyst for both CO oxidation and benzylamine oxidation. A 50% CO conversion was achieved at ∼349 and 330 K for Au/CeO2 and Au/Ce0.9Fe0.1O2−δ catalysts, respectively. As well, the Au/Ce0.9Fe0.1O2−δ catalyst showed ∼99% benzylamine conversion with ∼100% dibenzylimine selectivity for 7 h reaction time and 403 K temperature, whereas only 81% benzylamine conversion was achieved for the Au/CeO2 sample under similar conditions. The excellent performance of the Au/Ce0.9Fe0.1O2−δ catalyst is mainly due to the existence of smaller Au particles and an improved synergetic effect between the Au and the Ce0.9Fe0.1O2−δ support. It is confirmed that the oxidation efficiency of the Au catalysts is highly dependent on the preparation method.