Physicochemical characterization and catalytic CO oxidation performance of nanocrystalline Ce–Fe mixed oxides

Abstract

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 Ce_1−xFe_xO_2−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 FeO_x. 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.