X-ray photoelectron and Raman spectroscopy of nanostructured ceria in soot oxidation under operando conditions

摘要: Abstract Ceria nanoshapes exhibiting different amounts of {100}, {110} and {111} facets (cubes, rods, octahedra polyhedra) were prepared, characterized, tested in the carbon soot oxidation reaction, studied by operando near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) Raman up to 550 °C. The specific reaction rate (mgC·m−2·min−1) clearly indicated that {100} crystallographic planes ceria more active than ones for soot. As deduced from Ce 3d O 1s signals recorded using photon energies, all experienced progressive reduction upon increasing temperature under Ar, which was accompanied formation oxygen vacancies. studies revealed that, at this stage, isolated graphene layers reacted with lattice atoms following a Mars-Van Krevelen mechanism. After exposure O2 550 °C, broad signal region 531.2–532.5 eV ascribed surface species, such as peroxide (O22−) superoxide (O2−) generated interaction molecular vacancies, proved be highly reactive oxidize graphitic structures