Hollow and Core–Shell Nanostructure Co₃O₄ Derived from a Metal Formate Framework toward High Catalytic Activity of CO Oxidation

Hollow and core–shell particles are currently attracting global attention because of their special properties. We herein proposed a facile self-sacrificial template strategy for the synthesis of cobalt tetraoxide (Co 3 O 4 ) with hollow and core–shell nanostructures. Starting with metal formate framework (MFF) template [CH 3 NH 3 ][Co(HCOO) 3 ], a series of core–shell nanostructure MFF@Co(OH) 2 microboxes and hollow Co(OH) 2 -H were successfully obtained through a reaction between the MFF template and sodium hydroxide (NaOH) combined with different washing processes. Finally, hollow and core–shell nanostructure Co 3 O 4 products were obtained after calcination, which inherited the structures from corresponding precursors. In addition, the formation processes of hollow and core–shell nanostructures were studied. Moreover, the catalytic activity of the as-obtained Co 3 O 4 for carbon monoxide (CO) oxidation was investigated. Such hollow and core–shell nanostructures gave different physiochemical properties. Hollow structure Co 3 O 4 exhibited higher catalytic activity than that of core–shell nanostructure Co 3 O 4, which reached 100% CO conversion at 90 °C. Furthermore, the core–shell nanostructure Co 3 O 4 had higher long-term catalytic stability than that of the hollow structure Co 3 O 4 . We explored the relationships between the different structures and catalytic properties.