Engineering of Mn 3 O 4 @Ag microspheres assembled from nanosheets for superior O 3 decomposition.

Manganese oxides have wide application in the ambient decomposition of ozone, although their activities are affected by many parameters. Morphology engineering and metal doping are, together, one of the most effective methods to enhance catalytic activity for O 3 decomposition. Herein, a topochemical transformation route to Mn 3 O 4 nanospheres composed of 2D nanosheets is first provided by using layered β-MnOOH as the precursor. Then, silver nanoparticles are deposited over the Mn 3 O 4 nanosheets via a redox reaction without any extra reducing agents. In comparison with Mn 3 O 4 with a conventional octahedral morphology, the prepared Mn 3 O 4 nanosphere (Mn 3 O 4 -NF), and its Ag-doped composite, Mn 3 O 4 @Ag (Mn 3 O 4 @Ag-NF), both retain the morphology of β-MnOOH, and display better reducibility and higher oxygen vacancies. The best catalytic performance for O 3 decomposition is found over Mn 3 O 4 @Ag-NF, which exhibits ∼88.5% removal efficiency within 24 h at a space velocity of 600 L g -1 h -1 and a relative humidity of 50% at room temperature. This work emphasizes the advantages of nanosheet morphology and metal doping in optimizing the catalytic activity for O 3 elimination of manganese oxide.