Porous Ni–Mn oxide nanosheets in situ formed on nickel foam as 3D hierarchical monolith de-NOx catalysts

Abstract

In this work, we successfully in situ decorated nickel foam with porous Ni–Mn oxide nanosheets (3DH-NM/NF) as 3D hierarchical monolith de-NO_x catalysts via a simple hydrothermal reaction and calcination process. The catalysts were carefully examined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, elemental mapping, X-ray photoelectron spectroscopy, H₂ temperature-programmed reduction and NH₃ temperature-programmed desorption measurements. The results indicated that the nanosheets are composed of a Ni₆Mn₁O₈ spinel and the metal species are uniformly dispersed in bi-metal oxides. As a result, the strong synergistic effects between the Mn and Ni species have been observed. The active oxygen species, reducible species and acidity are enhanced by the in situ formation of the nanosheets on the surface of nickel foam. These desirable features of 3DH-NM/NF catalysts bring about the excellent de-NO_x performance. Moreover, the 3DH-NM/NF catalysts also present good stability and H₂O resistance. Based on these favorable properties, 3DH-NM/NF could be considered as a promising candidate for the monolith de-NO_x catalysts.