Activating Lattice Oxygen by Metal Cation Defect in 2D Co‐Based Spinel for Efficient CO Oxidation

Abstract Enhancing the catalytic oxidation activity and water resistance of non‐noble metal catalysts has long been a research focus in catalysis. Defect engineering has been proven to be an effective strategy for improving catalyst activity. However, research on cation defects, namely metal defects, remains scarce compared to anion defects. Herein, 2D ZnCo 2 O 4 nanosheets with Zn vacancies (V‐ZnCo 2 O 4 ) are synthesized. Compared with 2D Co 3 O 4 nanosheets (89.01 kJ mol −1 ), the activation energy for CO catalytic oxidation over 2D V‐ZnCo 2 O 4 significantly decreased to 56.06 kJ mol −1 . Moreover, stability tests under alternating gas atmospheres demonstrated that even in the presence of 5% H 2 O, the CO conversion over 2D V‐ZnCo 2 O 4 remained above 50%, and its activity can be restored within 2 h under dry conditions, remarkably outperforming 2D Co 3 O 4 , which exhibited a CO conversion rate of less than 5%. In situ XAFS, in situ DRIFTS, and theoretical calculations showed that Zn vacancies lead to the elongation of Co─O bonds, enhancing lattice oxygen reactivity while weakening the adsorption of intermediate species on active sites. This study provides a new perspective for designing efficient CO oxidation catalysts by achieving a dual benefit of low‐temperature lattice oxygen activation and water resistance by constructing metal defects instead of anion defects.