Time-resolved in situ UV/vis spectroscopy for analyzing the dynamics of surface and bulk redox processes in materials used as oxygen storage capacitors

Time-resolved UV/vis-DR (diffuse reflectance UV/vis) spectroscopy was used to in situ monitor the dynamics of reduction and reoxidation of Pt-free and Pt-containing CeO2–ZrO2 used as oxygen storage capacitors. This method can be also applied for measuring the speed of oxygen release. Combining the spectroscopic catalyst characterization with transient reaction analysis (alternating feeding of CO(H2) and O2) enabled us to identify factors determining surface and bulk redox processes of ceria. The presence of Pt increased strongly the mobility and availability of lattice oxygen in CeO2–ZrO2 for oxygen release reactions, while the presence of strongly polymerized CeOx species (non-homogeneous distribution of ZrO2 in CeO2) decreased the mobility of lattice oxygen. The results of the present in situ UV/vis-DR analysis support previous non-directly derived conclusions.