Solution Combustion Synthesis of High Surface Area CeO2 Nanopowders for Catalytic Applications: Reaction Mechanism and Properties

Abstract

High surface area cerium oxide (CeO2) is an important material as a catalyst component in many applications owing to its unique redox properties, high oxygen storage capacity, and ability to disperse metal on its surface. In this work, CeO2 nanopowders were prepared by solution combustion synthesis (SCS), varying the synthesis parameters in terms of precursor oxidizer (cerium nitrate hexahydrate and cerium ammonium nitrate), fuel (glycine and hydrous hydrazine), fuel-to-oxidizer ratio (0.5–3), and gas generating agent (ammonium nitrate). These parameters strongly influence the combustion features, including combustion temperature and amount of gas evolved during combustion, and, in turn, the properties of formed CeO2 powders. On the basis of the experimental results, the combustion reaction mechanism and correlation between the SCS parameters and properties of the resulting powder are discussed. The samples were characterized using X-ray diffraction, transmission electron microscopy, Raman, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller techniques. The tailored CeO2 nanopowder synthesized using hydrous hydrazine fuel, fuel-to-oxidizer ratio 2, and ammonium nitrate/metal nitrate ratio 4 exhibited small CeO2 crystallite size (7.9 nm) and high surface area (88 m2/g), which is the highest value among all prior reported SCS-derived CeO2 powders.