Understanding the Role of Pr Doping in Redox Enhancement of CeO ₂ for the Reverse Water–Gas Shift via Chemical Looping

Fluorite-type CeO2 was examined as an oxygen carrier material for the chemical looping reverse water–gas shift (RWGS-CL) for effective conversion of CO2 to CO, and potential dopants to enhance its redox properties were explored through a combination of theoretical calculations and experimental investigations. A strong correlation was observed between the oxygen vacancy formation energy, calculated using neural network potential (NNP) calculations, and the experimentally determined reduction rate under a H2 atmosphere, leading to the identification of praseodymium (Pr) as a promising dopant. The redox performance of Pr-doped CeO2 improved with increasing doping ratio, with Ce0.67Pr0.33O2 exhibiting the highest CO2 splitting capacity. In situ X-ray absorption fine structure (XAFS) analysis confirmed that Pr doping promotes the Ce4+ ↔ Ce3+ redox cycle during the RWGS-CL process at 773 K. Furthermore, NNP-based calculations revealed that Pr doping induces a positive shift in the charge of Ce atoms, thereby enhancing the redox capacity of the Pr-doped system.