Nickel

About: Nickel is a research topic. Over the lifetime, 79308 publications have been published within this topic receiving 1210058 citations. The topic is also known as: Ni & element 28.

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-NOx 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-NOx 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-NOx catalysts.

Synthesis of Nickel Hydroxide by Homogeneous Alkalinization. Precipitation Mechanism

Abstract: Uniform microcrystalline nickel(II) hydroxide particles have been prepared via the homogeneous alkalinization of nickel(II) nitrate solutions by urea hydrolysis. The nature of the precipitated solids depends on the temperature of synthesis. At ca. 423 K, i.e., under the hydrothermal conditions attained by microwave heating, β-Ni(OH)2 forms upon the fast ripening of α-Ni(OH)2. In the range 363−343 K, α-Ni(OH)2 is always the final product. The evolution of the systems during the precipitation of α-Ni(OH)2 is analyzed in terms of the kinetic factors that control nucleation and growth. A precipitation mechanism, based on the principle of minimal structural change, is proposed; it is suggested that the edge-on condensation of Ni4(OH)44+ tetramers is a key step in the sequence of events that conduct from hexaaquo Ni2+ to α-Ni(OH)2.