Key Words:Nickel compounds;Catalyst activity - Crystal structure - Doping (additives) - Energy dispersive spectroscopy - Fourier transform infrared spectroscopy - High resolution transmission electron microscopy - Infrared devices - Iron compounds - Scanning electron microscopy - Solutions - Thermogravimetric analysis - Transmission electron microscopy - X ray powder diffraction;Electrochemical measurements - Energy dispersive X ray spectroscopy - Fourier transform infra red (FTIR) spectroscopy - Interstratification - Iron doping - Nickel hydroxides - Scanning and transmission electron microscopy - Ssbauer spectroscopies
Abstract:This paper systematically examines the influence of the level of Fe(III) doping on the crystal structure and other properties of Ni(OH)<inf>2</inf>. Reference β-Ni(OH)<inf>2</inf>and Fe-doped Ni(OH)<inf>2</inf>samples were synthesized by hydrothermal precipitation of mixed Ni(II) and Fe(III) nitrate aqueous solutions in a highly alkaline medium. The samples were investigated using X-ray powder diffraction (XRPD), scanning and transmission electron microscopy (FE-SEM and TEM), energy dispersive X-ray spectroscopy (EDS), Mössbauer spectroscopy, magnetic measurements, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy, thermogravimetric analysis (TGA) and electrochemical measurements. Incorporation of Fe in β-Ni(OH)<inf>2</inf>by cation substitution was confirmed from the shifts in position of XRPD lines due to the difference in the ionic radius of Fe<sup>3+</sup>and Ni<sup>2+</sup>. The Fe<sup>3+</sup>-for-Ni<sup>2+</sup>substitution in β-Ni(OH)<inf>2</inf>caused formation of an interstratified structure with β-Ni(OH)<inf>2</inf>and α-Ni(OH)<inf>2</inf>structural units interconnected within the same structural layers and crystallites. Mössbauer spectra revealed the presence of Fe<sup>3+</sup>ions in highly distorted octahedral sites, presumably at the boundary between the α-Ni(OH)<inf>2</inf>and β-Ni(OH)<inf>2</inf>structural units within the same structural layer. Electrochemical measurements showed significant increase in oxygen evolution reaction (OER) catalytic activity of Fe-doped Ni(OH)<inf>2</inf>compared to pure phase.<br/> © 2018 Elsevier B.V.
Volume:750
Issue:
Translation or Not:no
