Tuning the Magnetic and Photocatalytic Properties of Wide Bandgap Metal Oxide Semiconductors for Environmental Remediation

The review focuses on recent developments towards preparing room temperature ferromagnetic metal oxide semiconductors for better photocatalytic performance. Here we reported the combined study of photocatalytic and ferromagnetic properties at room temperature on metal oxides, particularly TiO2, which is rapidly an emerging field in the development of magnetism and environmental remediation. Even after decades of research in this area, the exact mechanism of the combination of ferromagnetism and photocatalysis in these materials has been not understood completely. However, some of the critical factors were hinted about the contribution to magnetism. Many reports demonstrated that oxygen vacancy and various metal doping plays a primary role in the room temperature ferromagnetism and photocatalysis in wide-band-gap metal oxides. However, it is not easy to understand the direct correlation between magnetism, oxygen vacancies, dopant concentration, and photocatalysis. This review primarily aims to encompass the recent progress of metal oxide for understanding magnetism and photocatalyst under visible light

New monomeric mixed-ligand complex of iron(III)-3-chloropyridine: Synthesis, structure, luminescence, electrochemical and magnetic properties

The monomeric aquobis(3-chloropyridine)tri(chloro)iron(III) 3-chloropyridine complex, [FeIII(3-Clpy)2(H2O)Cl3]·3-Clpy is synthesized and characterized using spectroscopic techniques, single crystal X-ray diffraction, magnetic susceptibility and cyclic voltammetry techniques. The structural and spectroscopic features help to identify the formation of the mixed-ligand high spin complex. The theoretical calculation to determine the electronic, magnetic and optical properties were performed by Density Functional Theory using VASP calculation. The variable temperature magnetic susceptibility indicates the presence of a paramagnetic iron(III) center in the complex. Electrochemical studies of the complex with cyclic voltammetry showed cathodic peaks corresponding to a FeIII to FeII reduction. To the best of our knowledge, this is the first report on the synthesis and characterization of monomeric iron(III)-3-chloropyridine complex

Defect induced nickel, nitrogen-codoped mesoporous TiO2 microspheres with enhanced visible light photocatalytic activity

Nickel, nitrogen-codoped mesoporous TiO2 microspheres (Ni-N-TiO2) with high surface area, and an effective direct band gap energy of similar to 2.58 eV. Nickel sulfate used as the Ni source and ammonia gas as the N source here. The efficiency of the as-prepared samples was investigated by monitoring the degradation of Rhodamine B under visible light irradiation. The experimental results indicate that Ni-doped mesoporous TiO2 microspheres show higher photocatalytic activity than mesoporous TiO2 microspheres under visible light irradiation. It mainly due to that the electron trap level (Ni2+/Ni+) promoting the separation of charge carriers and the oxygen vacancies inducing the visible light absorption. In addition, Ni-N-TiO2 shows enhanced activity compared with Ni-TiO2. Codopants and dopants are found to be uniformly distributed in TiO2 matrix. Among the all samples the 0.5% molar quantity of Ni dopant and 500 degrees C 2 h nitriding condition gives the highest photocatalytic activity. The treatment of ammonia gas on Ni-TiO2 sample induced oxygen vancancies, substitutional and interstitial N. A suitable treatment by ammonia gas also promote separation of charge carriers and the absorption of visible light. The active species generated in the photocatalytic system were also investigated. The strategy presented here gives a promising route towards the development of a metal and non-metal codoped semiconductor materials for applied photocatalysis and related applications. (C) 2016 Elsevier Masson SAS. All rights reserved

One-pot synthesis visible-light-active TiO2 photocatalysts at low temperature by peroxotitanium complex

A series of TiO2 nanoparticles with different anatase/rutile ratio were prepared by peroxotitanium complex at low temperature (<= 200 degrees C). Our approach provides the notable advantage of a one-step reaction without any addition of solvents or pH-adjusting agents, which is green and energy-efficient. The structural, morphological, as well as spectroscopic properties of prepared samples were characterized by XRD, Raman, BET, TEM, UV-vis, XPS, FTIR and TG-MS techniques. The results showed that anatase fraction of TiO2 increased with the increase of aging temperature. Moreover, carbonate-like species, probably formed by the in-situ oxidation of the substituent group of titanium precursor by H2O2, was incorporated into the TiO2 matrix at certain temperatures (150 and 175 degrees C) and enhanced visible light absorption, such samples represented as T150 and T175. It was found that T150 and T175 exhibited the superior photocatalytic activity for the degradation of Rhodamine B (RhB) aqueous solution under visible light irradiation (lambda >= 400 nm), which is about 10-fold more active than commercial Evonik-Degussa P25. The excellent activity of as-prepared samples can be attributed to the enhanced visible light absorption and the enhanced dye adsorption capacity, and the plausible photocatalytic mechanism was studied. (C) 2018 Elsevier B.V. All rights reserved

Ferromagnetic nickel(II) imidazole-anatase framework: An enhanced photocatalytic performance

Nickel(II) imidazole-anatase composites with room temperature ferromagnetism and good photocatalytic activity were prepared by a simple adsorption method using [Ni(1-MeIm)(6)]Cl-2 center dot H2O complex and anatase TiO2 as starting materials in aqueous medium. The deposition of the surface species were elucidated by various conventional techniques. Ferromagnetic behavior was observed from vibrating sample magnetometer at room temperature. This composite has good visible light absorption ability than pristine TiO2. The adsorption and photocatalytic activity of the composite catalysts were evaluated by choosing methylene blue (MB) as organic pollutant under visible light irradiation. We first time report the Ni(II)-imidazole complex deposited on the anatase semiconductor with good photocatalytic and magnetic properties. This is expected to open up a general method for the synthesis of other transition metal loaded metal oxide semiconductor photocatalysts. (C) 2017 Elsevier B.V. All rights reserved

Visible-light-induced photocatalysis and peroxymonosulfate activation over ZnFe2O4 fine nanoparticles for degradation of Orange II

Refractory and non-biodegradable pollutants produced by industries have inevitably brought great threat to human life. Integrating several kinds of advanced oxidation processes (AOPs) into one system has been proposed to be an efficient strategy to remove such pollutants from the environment at low cost. In this study, magnetic zinc ferrite fine nanoparticles, firstly synthesized by a novel soft chemical solution process, showed super reactivity, good reusability and easy separation ability for visible-light-induced Orange II degradation in an integrated ZnFe2O4/PMS (peroxymonosulfate, 2KHSO(5)center dot KHSO4 center dot K2SO4, OXONE) aqueous system. Powder X-ray diffraction, transmission electron microscopy, and Fe-57 Mossbauer and X-ray photoelectron spectroscopy were employed to characterize the structure and morphology as well as recognize the physicochemical changes of the fine nanoparticles before and after the reaction. The generated oxidizing intermediates during the degradation process were detected by electron paramagnetic resonance spectroscopy and classic quenching experiments, which confirmed that both sulfate radical (SO4 center dot-) and hydroxyl radical (. OH) co-existed in the degradation process. The systematic condition experiments further verified the dual functionality of the ZnFe2O4/PMS system, which actively acted as a photocatalyst and a PMS activator for dye molecule oxidation under visible light irradiation. This study proves that photocatalysis and PMS activation for remediation of organic pollutants in water can be easily integrated into one system by using zinc ferrite nanoparticles as an environmentally friendly catalyst

Photoinduced Interfacial Electron Transfer in 2,2 '-Bipyridyl Iron(III) Complex-TiO2 Nanoparticles in Aqueous Medium

The near-UV and visible light induced interfacial electron transfer (IFET) process between aqueous solution of [Fe(bipy)(2) Cl-2][FeCl4] complex and TiO2 NPs has been proved at first time and the photochemical products were mainly characterized by electronic absorption, Fe K-edge X-ray absorption fine structure, electron paramagnetic resonance and Fe-57 Mossbauer spectroscopic method. This study makes in comprehending for the combination of semiconductor NPs and metal complex, in-particularly ionic salt like complex has potential in environmental friendly synthesis and remediation process

Bis(1,10-phenanthrolin-1-ium) tetrachloridozincate monohydrate

In the crystal structure of the title compound, (C12H9N2)2[ZnCl4]·H2O, the two independent 1,10-phenanthrolinium cations are bridged by the water molecule and the tetrahedral tetrachloridozincate anion via N—H...O, O—H...Cl and N—H...Cl hydrogen bonds, forming chains along [100]. The chains are linked via C—H...Cl hydrogen bonds and a number of π–π interactions [centroid–centroid distances vary from 3.5594 (14) to 3.7057 (13) Å], forming a three-dimensional network. In each 1,10-phenanthrolinium cation, there is a short N—H...N interaction

Cobalt-iron Oxide, Alloy and Nitride: Synthesis, Characterization and Application in Catalytic Peroxymonosulfate Activation for Orange II Degradation

In meeting the need for environmental remediation in wastewater treatment and the development of popular sulfate-radical-based advanced oxidation processes (SR-AOPs), a series of Co/Fe-based catalysts with confirmed phase structure were prepared through extended soft chemical solution processes followed by atmosphere-dependent calcination. Powder X-ray diffraction (XRD),scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fe-57 Mossbauer spectroscopy were employed to characterize the composition, morphology, crystal structure and chemical state of the prepared catalysts. It was shown that calcination in air, nitrogen and ammonia atmospheres generated Co-Fe catalysts with cobalt ferrite (CoFe2O4), Co-Fe alloy and Co-Fe nitride as dominant phases, respectively. The prepared Co/Fe-based catalysts were demonstrated to be highly efficient in activating peroxymonosulfate (PMS) for organic Orange II degradation. The activation efficiency of the different catalysts was found to increase in the order CoFe2O4 < Co-Fe nitride < Co-Fe alloy. Sulfate radical was found to be the primary active intermediate species contributing to the dye degradation for all the participating catalysts. Furthermore, a possible reaction mechanism was proposed for each of the studied catalysts. This study achieves progress in efficient cobalt-iron catalysts using in the field of SR-AOPs, with potential applications in environment remediation