Influence of Fe(III) doping on the crystal structure and properties of hydrothermally prepared ß-Ni(OH)^sub 2^ nanostructures

• Published in: Journal of alloys and compounds 2018-06, Vol.750, p.687
• Main Authors: Krehula, S, Ristic, M, Wu, C, Li, X, Jiang, L, Wang, J, Sun, G, Zhang, T, Perovic, M, Boškovic, M, Antic, B, Krehula, L Kratofil, Kobzi, B, Kubuki, S, Music, S
• Format: Article
• Language: English
• Subjects: Catalysis; Catalytic activity; Chemical precipitation; Crystal structure; Crystallites; Doping; Energy dispersive X ray spectroscopy; Energy transmission; Ferric ions; Fourier transforms; Infrared analysis; Infrared spectroscopy; Iron; Magnetic measurement; Mossbauer spectroscopy; Nanostructured materials; Near infrared radiation; Nickel compounds; Oxygen evolution reactions; Scanning electron microscopy; Spectroscopic analysis; Substitution reactions; Thermogravimetric analysis; Transmission electron microscopy; X ray powder diffraction
• ISSN: 0925-8388; 1873-4669

This paper systematically examines the influence of the level of Fe(III) doping on the crystal structure and other properties of Ni(OH)2. Reference β-Ni(OH)2 and Fe-doped Ni(OH)2 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)2 by cation substitution was confirmed from the shifts in position of XRPD lines due to the difference in the ionic radius of Fe3+ and Ni2+. The Fe3+-for-Ni2+ substitution in β-Ni(OH)2 caused formation of an interstratified structure with β-Ni(OH)2 and α-Ni(OH)2 structural units interconnected within the same structural layers and crystallites. Mössbauer spectra revealed the presence of Fe3+ ions in highly distorted octahedral sites, presumably at the boundary between the α-Ni(OH)2 and β-Ni(OH)2 structural units within the same structural layer. Electrochemical measurements showed significant increase in oxygen evolution reaction (OER) catalytic activity of Fe-doped Ni(OH)2 compared to pure phase.