Determination of redox-active centers in praseodymium doped ceria by in situ-XANES spectroscopy

► The reduction of Pr4+ to Pr3+ in Ce0.8Pr0.2O2 was investigated in situ up to 500 °C. ► The reversibility of the reaction can be monitored in situ. ► Measured Pr3+concentration is in agreement with thermodynamic calculations. ► Role of oxygen partial pressure and catalytic reactions evaluated.