Structure-induced hollow Co 3 O 4 nanoparticles with rich oxygen vacancies for efficient CO oxidation

Co 3 O 4 has been considered as one kind of promising catalysts for the oxidation of CO. According to the Mars-van Krevelen mechanism, oxygen vacancies of Co 3 O 4 play a significant role in catalytic activity. Herein, we report a novel structure-induced strategy to develop hollow Co 3 O 4 with rich oxygen vacancies for efficient oxidation of CO. Through a reduction-oxidation pyrolysis process, the metal-organic frameworks (MOFs) precursor (i.e., ZIF-67) is transformed into H-Co 3 O 4 @H-C, in which hollow Co 3 O 4 (H-Co 3 O 4 ) nanoparticles (NPs) are embedded in hollow carbon (H-C) shell. The hollow Co 3 O 4 NPs feature rich oxygen vacancies and finish a complete conversion of CO at 130°C, which is much lower than that of solid Co 3 O 4 (the temperature of full CO conversion T 100 =220°C). Besides, the hollow carbon shell could also reduce the diffusion resistance during the oxidation process. Benefiting from the unique hollow structures, H-Co 3 O 4 @H-C even shows comparable activity to noble metal catalysts under high weight hourly space velocities (WHSVs) up to 240,000 mL h −1 g cat. −1 . Furthermore, the H-Co 3 O 4 @H-C catalyst also shows good durability with only a slight decline after the reaction has been operated for 24 h.