Eu³⁺ Species as a Luminescent Probe for Fast Monitoring of the Chemical State of Ceria Catalysts

Complex luminescence, structure (powder XRD, Raman spectroscopy), and reducibility (NAP-XPS and H₂-TPR) studies carried out on classic ceria-based materials have allowed us to develop a new luminescence-based technique for fast monitoring of the chemical state of a ceria catalyst under operating conditions. The proposed approach involves a remote structural probe based on Eu³⁺ luminescence to probe the Ce³⁺/Ce⁴⁺ ratio in the ceria matrixa crucial factor in determining the catalytic activity of ceria-based materials. The sensitivity, remote readout mode, and simplicity of the proposed method, as well as its good correlation with a classic direct technique for the in situ study of the chemical state of materials (NAP-XPS) opens up new possibilities to control the state of the working catalysts in real industrial processes.