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The photo-Fenton properties of iron silicate composite materials were investigated by methylene blue dye degradation. From various iron oxide and iron silicate samples the best performing material, FeSiOx (bulk iron silicate) showed a first-order rate constant of (1.57 ± 0.04) × 10−2 min−1. According to the 57Fe Mossbauer spectra, XRD patterns and TEM images this sample showed the most amount of Fe2+ content in the form of Fe2SiO4 nanoprecipitations.

The relationship between local structure and visible-light photocatalytic ability of tin silicate glass prepared by sol–gel method was investigated. 119Sn Mossbauer spectrum of SnOx SiO2 glass prepared from SnCl2 showed a small peak of SnII component besides the major amount of SnIV. The smallest bandgap energy of 2.5 ± 0.5 eV was estimated from Tauc plot, and the largest first order rate constant (k) of (13.8 ± 0.1) 10-3 min-1 was recorded from the methylene blue degradation test under visible-light irradiation. It is concluded that SnII shows remarkable photocatalytic ability when it is incorporated into silica glass matrix.

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 beta-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), Mossbauer 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 beta-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 Ni-2. The Fe-3-for-Ni2+ substitution in beta-Ni(OH)(2) caused formation of an interstratifled structure with beta-Ni(OH)(2) and alpha-Ni(OH)(2) structural units interconnected within the same structural layers and crystallites. Mossbauer spectra revealed the presence of Fe3+ ions in highly distorted octahedral sites, presumably at the boundary between the alpha-Ni(OH)(2) and beta-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. (C) 2018 Elsevier B.V. All rights reserved.

A relationship between structure and visible light-activated photocatalytic activity of iron-containing soda lime aluminosilicate (15Na2O⋅15CaO⋅40Fe2O3⋅xAl2O3⋅(30−x)SiO2) glass (xNCFAS) was investigated by means of 57Fe-Mossbauer spectroscopy, X-ray diffractometry (XRD) and UV–visible light absorption spectroscopy (UV–VIS). The 57Fe-Mossbauer spectrum of 11NCFAS glass measured after heat-treatment at 1000 °C for 100 min was composed of a paramagnetic doublet due to FeIII(Td) and two magnetic sextets due to regular hematite (α-Fe2O3) and hematite with larger internal magnetic field. X-ray diffraction patterns of heat-treated xNCFAS samples resulted in decrease of α-Fe2O3 and increase of Ca2Fe22O33 or CaFe2O4 with alumina content. A quick decrease in methylene blue (MB) concentration from 15.6 to 4.7 μmol L−1 was observed in the photocatalytic reaction test with 40 mg of heat-treated 11NCFAS glass under visible light-exposure. The largest first-order rate constant of MB decomposition (k) was estimated to be 9.26 × 10−3 min−1. Tauc’s plot yielded a band gap energy (Eg) of 1.88 eV for heat-treated 11NCFAS glass, which is smaller than previously reported Eg of 2.2 eV for α-Fe2O3. These results prove that addition of Al2O3 into iron-containing soda lime silicate glass is favorable for the preparation of improved visible light-photocatalyst with ‘ubiquitous’ elements.

International journal of molecular sciences 14(5), 9722-9736 (2013). doi:10.18154/RWTH-CONV-085528, Published by Molecular Diversity Preservation International, Basel