Oxygen Gateway Effect of CeO(2)/La(2)O(2)SO(4) Composite Oxygen Storage Materials

[Image: see text] A synergistic enhancement in oxygen release/storage performance was achieved with composites formed between CeO(2) as an oxygen gateway and La(2)O(2)SO(4) as an oxygen reservoir. CeO(2) smoothly transfers oxygen atoms between La(2)O(2)SO(4) and the gas phase, whereas La(2)O(2)SO(4) stores a large amount of oxygen. The composite materials exhibited enhanced anaerobic CO oxidation and reversible oxygen storage in the presence of impregnated Pt catalysts as compared to their individual constituents (Pt/CeO(2) and Pt/La(2)O(2)SO(4)). In situ X-ray diffraction and Raman experiments demonstrated that CeO(2) significantly accelerated the redox reaction between La(2)O(2)SO(4) (S(6+)) and La(2)O(2)S (S(2–)), while preserving its structure. The reaction between CO and CeO(2)/(18)O-labeled La(2)O(2)SO(4) composites suggested that CO mainly reacted with the lattice oxygen atoms of CeO(2), and the resulting oxygen vacancies were subsequently filled with oxygen atoms supplied by La(2)O(2)SO(4). This oxygen gateway effect of CeO(2) greatly enhanced the oxygen release/storage rates of La(2)O(2)SO(4), while maintaining the high oxygen storage capacity, which is an advanced feature of oxysulfate materials. The synergistic effect is mostly pronounced when the two different oxygen storage materials are in intimate contact to form a three-phase boundary.