Isotopic Oxygen Exchange between CeO2 and O2: A Heteroexchange Mechanism

Isotopic oxygen exchange (IOE) is a crucial reaction required in the purification of (PuO2)-Pu-238 which has been used as an important fuel in space exploration. Experimental studies on the IOE between (PuO2)-Pu-238 and O-2 are costly and hazardous due to the radioactivity. With extremely similar crystal structures, CeO2 could be a fair surrogate for (PuO2)-Pu-238 in the investigation of physicochemical properties. Here, we perform density functional theory calculations to simulate the IOE between CeO2 and O-2, wherein a heteroexchange mechanism is proposed. Estimated reaction barriers for CeO2/O-2 and (PuO2)-Pu-238/O-2 systems are comparable (25.8 and 29.3 kcal mol(-1) respectively), indicating CeO2 is a potential substitute for (PuO2)-Pu-238 in an IOE reaction. Our study could be useful for experimental chemists to probe more complicated IOE mechanisms for both CeO2/O-2 and PuO2/O-2.