Role of Multivalent Pr in the Formation and Migration of Oxygen Vacancy in Pr-Doped Ceria: Experimental and First-Principles Investigations

We combined first-principles calculations with several experimental studies to investigate the complex role for high oxygen storage capacity (OSC) in multivalent Pr-doped ceria. TPR and Raman spectra were measured for confirming oxygen vacancy concentration and oxygen mobility. The coordination number was fitted via EXAFS spectra, and it was the correlated DFT calculation that has been corrected as effective U (5.3 eV) to well express the reducing state (4+ -> 3+) for both Ce and Pr elements. In our study, when Pr is incorporated into pure ceria, Pr3+ and Pr4+. ions are incorporated as majority and minority ions, respectively. Pr3+ ions play a key role to create oxygen vacancies and induce a local distortion, which improves oxygen mobility, and Pr4+ can contribute to diminishing reduction energy and a respectable OSC via the formation of an additional redox couple.