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This work is devoted to the systematic study of the optical and magneto-optical properties of sputter deposited CuFe2O4 thin films in the photon energy region between 2 and 5 eV using spectroscopic ellipsometry and magneto-optical Kerr spectroscopy. The spectral dependence of both the diagonal and off-diagonal elements of the permittivity tensor is determined. A complete picture about the electron transitions in CuFe2O4 is suggested in the frame of intervalence charge transfer and intersublattice charge transfer transitions. The effect of deposition conditions and post-deposition treatment in CuFe2O4 films upon the optical and magneto-optical properties is discussed.

This paper is the first description of natural copper-rich oxide spinels. They were found in deposits of oxidizing-type fumaroles related to the Tolbachik volcano, Kamchatka, Russia. This mineralization is represented by nine species with the following maximum contents of CuO (wt.%, given in parentheses): a new mineral thermaerogenite, ideally CuAl2O4 (26.9), cuprospinel, ideally CuFe3+2O4 (28.6), gahnite (21.4), magnesioferrite (14.7), spinel (10.9), magnesiochromite (9.0), franklinite (7.9), chromite (5.9), and zincochromite (4.8). Cuprospinel, formerly known only as a phase of anthropogenic origin, turned out to be the Cu-richest natural spinel-type oxide [sample with the composition (Cu0.831Zn0.100Mg0.043Ni0.022)Σ0.996(Fe3+1.725Al0.219Mn3+0.048Ti0.008)Σ2.000O4 from Tolbachik]. Aluminum and Fe3+-dominant spinels (thermaerogenite, gahnite, spinel, cuprospinel, franklinite, and magnesioferrite) were deposited directly from hot gas as volcanic sublimates. The most probable temperature interval of their crystallization is 600⁻800 °C. They are associated with each other and with tenorite, hematite, orthoclase, fluorophlogopite, langbeinite, calciolangbeinite, aphthitalite, anhydrite, fluoborite, sylvite, halite, pseudobrookite, urusovite, johillerite, ericlaxmanite, tilasite, etc. Cu-bearing spinels are among the latest minerals of this assemblage: they occur in cavities and overgrow even alkaline sulfates. Cu-enriched varieties of chrome-spinels (magnesiochromite, chromite, and zincochromite) were likely formed in the course of the metasomatic replacement of a magmatic chrome-spinel in micro-xenoliths of ultrabasic rock under the influence of volcanic gases. The new mineral thermaerogenite, ideally CuAl2O4, was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption. It forms octahedral crystals up to 0.02 mm typically combined in open-work clusters up to 1 mm across. Thermaerogenite is semitransparent to transparent, with a strong vitreous lustre. Its colour is brown, yellow-brown, red-brown, brown-yellow or brown-red. The mineral is brittle, with the conchoidal fracture, cleavage is none observed. D(calc.) is 4.87 g/cm3. The chemical composition of the holotype (wt.%, electron microprobe) is: CuO 25.01, ZnO 17.45, Al2O3 39.43, Cr2O3 0.27, Fe2O3 17.96, total 100.12 wt.%. The empirical formula calculated on the basis of 4 O apfu is: (Cu0.619Zn0.422)Σ1.041(Al1.523Fe3+0.443Cr0.007)Σ1.973O4. The mineral is cubic, Fd-3m, a = 8.093(9) Å, V = 530.1(10) Å3. Thermaerogenite forms a continuous isomorphous series with gahnite. The strongest lines of the powder X-ray diffraction pattern of thermaerogenite [d, Å (I, %) (hkl)] are: 2.873 (65) (220), 2.451 (100) (311), 2.033 (10) (400), 1.660 (16) (422), 1.565 (28) (511) and 1.438 (30) (440).

A novel composite composed of (5, 10, 15, 20-tetraphenyl) porphinato manganese sensitized p-type CuFe2O4 was developed for constructing the photocathode of a tandem photoelectrochemical (PEC) cell. The prepared material was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (DRS). Light-driven water splitting to produce hydrogen can be achieved through the PEC cell, and the results show that H2 and O2 can be collected separately at low applied bias. This work demonstrates that manganese porphyrin sensitized CuFe2O4 is an effective hybrid material for building the photocathode of a PEC cell for solar water splitting to produce H2.

• Oxygen vacancy played a key role in Hg0 capture on CuFe 2 O 4. • Reaction mechanism of H 2 S with Hg0 on oxygen vacancy CuFe 2 O 4. • Increased impact of oxygen vacancy on the adsorption capacity of the key intermediates. • Increased impact of oxygen vacancy on the thermodynamic stability of *S and HgS. The reaction mechanism of H 2 S and Hg0 on CuFe 2 O 4 with oxygen vacancy structure was thoroughly analyzed by X-ray photoelectron spectroscopy (XPS) characterization and Density Functional Theory (DFT) calculations. XPS characterization revealed H 2 S can produce active S*, and the active S* will combine with Hg0 to form HgS. DFT calculation results revealed that oxygen vacancy enhanced the adsorption capacity of Hg, H 2 S, and HgS on CuFe 2 O 4. The d-band center of Fe(Cu) indicated that the increased adsorption energy is related to the enhanced hybridization between Fe(Cu) and Hg(S) molecular orbitals by oxygen vacancies. Furthermore, ΔE des of HgS desorption (2.13 eV) is higher than E *HgS (1.10 eV), the desorption of HgS is a rate-limiting step in O-defective CuFe 2 O 4. The Brønsted−Evans−Polanyi relation implied that oxygen vacancies significantly enhanced the adsorption capacity of key intermediates *HS and S* on CuFe 2 O 4 , improved the energy barrier of the rate-determining step (RDS) (HS*→S*+H*, S*+Hg*→HgS*), and enhanced the thermodynamic stability of S* and HgS. It is difficult for S* and HgS to desorb from O-defective CuFe 2 O 4. This paper provides an in-depth insight into the reaction mechanism of H 2 S and Hg0 on oxygen vacancy CuFe 2 O 4 oxygen carriers. [ABSTRACT FROM AUTHOR]

A magnetic copper ferrite (CuFe 2 O 4) photocatalyst was successfully synthesized by the modified microwave-assisted co-precipitation method to improve the removal performance of tetracycline (TC) and the reusability of a photocatalyst. A series of tests indicate that microwaves could reach the inside of the material quickly and uniformly with its energy so that CuFe 2 O 4 exhibited a more significant specific surface area, magnetic intensity, and separation efficiency of photogenerated electron-hole pairs. CuFe 2 O 4 reached superior photo-Fenton performance of TC in the presence of Cl-, NO 3 –, HCO 3 –, HPO 4 2–, SO 4 2– and humic acid, as well as deionized water, river water, and secondary effluent. Ten recycling tests in these three different water quality backgrounds confirmed the stability and remarkable activity of CuFe 2 O 4 , with the removal rate only decreasing by 2.0 %, 1.5 %, and 2.1 %, respectively. Free radical capture experiments as well as electron spin resonance suggest that·OH and O 2 ·- were mainly involved in the degradation of TC, and the photo-Fenton degradation mechanism and equations were proposed. Toxicity evaluation declared that CuFe 2 O 4 photo-Fenton degradation of TC was a safe and promising technology. This study offered prospects of magnetic CuFe 2 O 4 prepared by the modified microwave-assisted co-precipitation method in TC wastewater treatment. [Display omitted] • CuFe 2 O 4 was constructed by the modified microwave-assisted co-precipitation method. • Microwave assistance significantly enhanced the performance of CuFe 2 O 4. • CuFe 2 O 4 exhibited efficient tetracycline removal in the presence of anions. • CuFe 2 O 4 exhibited efficient tetracycline removal under different water quality. • Excellent magnetic properties of CuFe 2 O 4 facilitated its separation and recycling. [ABSTRACT FROM AUTHOR]

• PANI/GO/CuFe 2 O 4 nanocomposite was synthesized using in situ polymerization. • High specific capacitance of 614.76 F/g at current density of 1 A/g for PANI/GO/CuFe 2 O 4 nanocomposite. • Ternary hybrid system showed the highest capacitance retention of 88% after 3500 cycles. • High energy density of 49.72 Wh/kg and power density of 923 W/kg were achieved. Storage of energy and the pollution of the environment are two of the world's primary challenges currently. As a consequence of the diminishing supply of fossil fuels, renewable energy production has become of great significance. As a result of the high energy/power density and extended life cycle of hybrid supercapacitors, these have recently attracted the attention of energy experts. As new hybrid supercapacitor electrodes, a straightforward two-step technique was developed and constructed a ternary PANI/GO/CuFe 2 O 4 nanocomposite. The copper ferrite (CuFe 2 O 4) nanoparticles were disseminated on graphene oxide (GO) sheets, utilizing a hydrothermal approach, followed by an in situ polymerization procedure for a coating with polyaniline (PANI). Various electrochemical techniques were utilized to evaluate the instances' electrochemical characteristics, and the ternary system's linked topology enabled an array of electrochemical characterizations.In comparison to studies of single and binary samples, the ternary PANI/GO/CuFe 2 O 4 electrode had the highest specific capacitance (SC) of 614.76 F/g at 1 A/g and the best cycle stability (remaining at 88% after 3,500 cycles) while exhibiting the lowest resistance in electrochemical impedance spectroscopy. A constructed asymmetric supercapacitor that utilized hybrid PANI/GO/CuFe 2 O 4 //GO electrodes indicated an SC of 124 F/g at 1 A/g. The asymmetric supercapacitor provided 49.72 Wh/kg and 923 W/kg energy density and specific power, respectively. These findings indicate that the ternary PANI/GO/CuFe 2 O 4 composite material has the capability to be employed as unique electrode material in supercapacitor applications to produce high-efficiency and reliable energy storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

The magnetically separable nano CuFe2O4was prepared and used as an efficient heterogeneous catalyst for conversion of various epoxides to the corresponding thiiranes with thiourea in refluxing ethanol. The reactions were completed within 34−45 min to give thiiranes in 80−95% yields. The utilized nano CuFe2O4can be reused for several times without losing its activity. [ABSTRACT FROM PUBLISHER]

The heterogeneous Fenton-like catalysts based on CuFe2O4 were prepared by polymeric precursor method at several annealing temperatures. The obtained catalysts were respectively characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, point of zero charge measurement, and vibrating sample magnetometer. The Fenton-like catalytic activity was evaluated via the oxidation of methylene blue with H2O2. The results show that the CuFe2O4 phase content and the particle size increase with the annealing temperatures whereas the surface OH groups and the surface acidity decrease. The prepared powders possess typical ferromagnetic properties which allow them to be easily recovered and reused. These catalysts also present highly catalytic activities for the oxidation of methylene blue, which is principally attributed to the catalysis of the CuFe2O4 phase. When the annealing temperature increased, the catalytic performance was reduced, corresponding to the increase of particle size and the decrease of surface OH groups. [ABSTRACT FROM AUTHOR]

[Display omitted] • Roles of CuFe 2 O 4 in Hg0 adsorption and oxidation on CuFe 2 O 4 -modified bentonite. • Hg0 adsorption and oxidation mechanism of CuFe 2 O 4 established. • The adsorption of Hg0 on the surface of CuFe 2 O 4 (1 1 0) have the stronger interaction. Taking spinel CuFe 2 O 4 -modified bentonite as the research object, the experimental and thermodynamic techniques were integrated to study the effect of CuFe 2 O 4 active components on removing Hg0 in coal gasification process. Meanwhile, the density functional theory was adopted to identify the CuFe 2 O 4 's adsorption and oxidation mechanisms for Hg0. The results showed that the doping of CuFe 2 O 4 increased the active sites for adsorbing Hg0 on the surface of bentonite and enabled bentonite with effective magnetic properties. Compared with pure bentonite, the CuFe 2 O 4 -modified one was able to convert more Hg0 into Hg2+ and particulate mercury[Hg(P)], which exhibited its better capacities of adsorbing and catalyzing Hg0. The thermodynamic simulation outcomes further verified that the bentonite adsorbent modified by CuFe 2 O 4 became more conducive to the conversion of Hg0 to Hg2+. Moreover, DFT results also presented that Hg0 was under stronger adsorption effect at the Cu-top active sites of CuFe 2 O 4 (1 1 0), which was closely related to the hybridization of orbitals between Hg and Cu atoms. The reaction of Hg0 with O atoms followed the Markov-Mason mechanism, meaning that Hg diffusion at Fe/Cu-top site was the controlling step, HgO desorption at O-top site and hollow was the control step. The reaction of Hg0 with active S atoms followed the two mechanisms of Eley−Riddel(E−R) and Langmuir−Hinshlwood (L−H). The energy barrier of L-H mechanism was lower than that of E-R mechanism, which was dominant in the reaction process. The excellent performance suggested that the CuFe 2 O 4 -modified bentonite was a promising sorbent for mercury removal in coal gasification. [ABSTRACT FROM AUTHOR]

• Theoretical and practical methods were used to study the impact of Eu3+ substitution on copper ferrites. • The intensity of quadrupole split lines decreases along with the reduction in temperature. • The presence of paramagnetic lines at temperatures lower than the Curie temperature, asymmetric lines. • DFT calculations support the preference for octahedral Eu-doping in combination with the CuFe 2 O 4 matrix. Here, theoretical and practical methods were used to study the impact of Eu3+ substitution on copper ferrites. The spinel cubic structure of the synthesised samples is crystalline, and XRD analysis revealed the presence of a trace amount of the impurity Fe 2 O 3 phase. The range of the estimated crystallite sizes is between 18 and 27 nm. FTIR spectra of the ferrites exhibited the presence of functional groups of spinel ferrites. The temperature-dependent Mössbauer spectra of CuFe 2-x Eu x O 4 (x = 0, 0.01, 0.02, 0.03) (CEF) were collected at 300 K, 200 K, 100 K, and 14 K. Room temperature spectra consist of asymmetrically broadened sextets and quadruple split lines. The intensity of quadrupole split lines decreases along with the reduction in temperature. The observed changes in the structure of the Mössbauer spectra are typical of nanosized particles. The presence of paramagnetic lines at temperatures lower than the Curie temperature, asymmetric lines with sharp external fronts, and significantly diffused internal fronts is a sign of superparamagnetic relaxation. The partial substitution of Fe3+ ions by Eu3+ ions causes the redistribution of A and B cations, which leads to the alteration in angle and bond length of magnetic superexchange links. DFT calculations support the preference for octahedral Eu-doping in combination with the CuFe 2 O 4 matrix, which results in local structural disorders that affect both the material's magnetic and electrical characteristics. The size, shape, interaction with the matrix, and crystallite characteristics all affect the material's magnetic properties. A weak ferromagnetic characteristic is indicated by the magnetic properties, and the magnetization values increase as Eu increases as a result of changes in crystallite size. As a result, our findings imply that synthesised samples are appropriate for applications involving hyperthermia. [ABSTRACT FROM AUTHOR]

[Display omitted] • WO 3 -CuFe 2 O 4 Z-scheme catalyst was constructed. • Quinoline removal was realized by persulfate-assisted photocatalytic process. • Photogenerated holes and ·OH were the main reactive species. • Degradation mechanism and pathways of quinoline were explored. Quinoline is a kind of organic pollutant difficult to be biodegraded, for which the photocatalysis technology is a commonly used removal method, but the degradation performance still needs to be improved. In this work, the WO 3 -CuFe 2 O 4 Z-scheme system was constructed, and the persulfate (PS)-assisted photocatalytic degradation of quinoline with WO 3 -CuFe 2 O 4 by adding persulfate in the photocatalytic systems was studied. The effects of different systems and key parameters such as catalyst dosage, PS concentration and initial pH value on the degradation efficiency of quinoline were investigated. With the addition of persulfate, the degradation efficiency of quinoline increased from 24.3% to 100% in 150 min, under the condition of [PS] = 3 mmol/L, [catalyst] = 3 g/L, temperature = 25 ± 2 °C, and pH = 9. And the WO 3 -CuFe 2 O 4 catalyst showed excellent reusability according to the result of 5-cycle repeated experiment. The possible degradation mechanism was studied by the quenching test and the identification of intermediates and products, which indicated the degradation of quinoline in WO 3 -CuFe 2 O 4 /VIS/PS system was realized via denitrification, dehydrogenation, hydroxylation and ring breaking processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D porous CuFe 2 O 4 was synthesized by a polymer-assisted freeze-drying method. • The samples had outstanding mass transfer ability and high specific surface area. • 3D porous CuFe 2 O 4 /Vis/PMS system realized effective degradation of TCH. • Photogenerated electrons promoted PMS activation and metal sites circulation. • The samples had excellent stability and recyclability. Three dimensional porous CuFe 2 O 4 (CuFe 2 O 4 3DPs) catalysts were prepared using the polymer-assisted freeze-drying method. Then, the formation mechanism of the porous structure, as well as their effects on mass transfer, were comparatively studied and carefully analyzed. The mass transfer rate of the CuFe 2 O 4 3DPs was 21.1 and 9.0 times that of the CuFe 2 O 4 nanosheets (NSs) prepared without polymer assistance, and the CuFe 2 O 4 nanoparticles (NPs) prepared without freeze-drying, respectively. The catalytic performance of the CuFe 2 O 4 3DPs for visible-light (Vis)-driven peroxymonosulfate (PMS) activation technology was studied through the degradation of tetracycline hydrochloride (TCH). A pseudo-first-order kinetics degradation constant of CuFe 2 O 4 3DPs was achieved at 0.071 min−1, which was 3.2 and 2.2 times higher than the CuFe 2 O 4 NSs and CuFe 2 O 4 NPs, respectively. Electron paramagnetic resonance and capture experiments on the CuFe 2 O 4 3DPs/Vis, CuFe 2 O 4 3DPs/PMS, and CuFe 2 O 4 3DPs/Vis/PMS systems demonstrated that the three factors on the CuFe 2 O 4 3DPs/Vis/PMS system exhibited a strong synergistic effect in the degradation process. The photogenerated electrons could directly activate PMS and produce more SO 4 − and OH species. In addition, the photogenerated electrons could promote cycling between Cu3+/Cu2+, Cu2+/Cu+, and Fe3+/Fe2+, reduce the concentration of H+, accelerate the activation of PMS, and reduce the leaching of Cu and Fe ions. Meanwhile, the degradation pathway of TCH was analyzed and proposed via liquid chromatography-mass spectrometry analysis. The CuFe 2 O 4 3DPs were easily separated and recycled due to their macroscopic self-supporting structure and good mechanical stability, offering good prospects for sustainable development and chemical applications. [ABSTRACT FROM AUTHOR]

The Jahn-Teller effect at Cu2+ in cuprospinel CuFe2O4 was investigated using high-pressure single-crystal synchrotron X-ray diffraction techniques at beamline BL10A at the Photon Factory, KEK, Japan. Six data sets were collected in the pressure range from ambient to 5.9 GPa at room temperature. Structural refinements based on the data were performed at 0.0, 1.8, 2.7, and 4.6 GPa. The unit-cell volume of cuprospinel decreases continuously from 590.8(6) to 579.5(8) Å3 up to 3.8 GPa. Least-squares fitting to a third-order Birch-Murnaghan equation of state yields the zero-pressure volume V0 = 590.7(1) Å3 and bulk modulus K0 = 188.1(4.4) GPa with K′ fixed at 4.0. The structural formula determined by electron microprobe analysis and site occupancy refinement is represented as T(Fe3+0.90Cu2+0.10)M(Fe3+1.10Fe2+0.40Cu2+0.50)O4. Most of the Cu2+ are preferentially distributed onto the octahedrally coordinated (M) site of the spinel structure. With pressure, the arrangement of the oxygen atoms around the M cation approaches a regular octahedron. This leads to an increase in the electrostatic repulsion between the coordinating oxygen ions and the 3dz2 orbital of MCu2+. At 4.6 GPa, a cubic-tetragonal phase transition is indicated by a splitting of the a axis of the cubic structure into a smaller a axis and a longer c axis, with unit-cell parameters a = 5.882(1) Å and c = 8.337(1) Å. The tetragonal structure with space group I41/amd was refined to R1 = 0.0332 and wR2 = 0.0703 using 38 observed reflections. At the M site, the two M-O bonds parallel to the c-axis direction of the unit cell are stretched with respect to the four M-O bonds parallel to the a-b plane, which leads to an elongated octahedron along the c-axis. The cubic-to-tetragonal transition induced by the Jahn-Teller effect at Cu2+ is attributable to this distortion of the CuO6 octahedron and involves Cu 3dz2 orbital, ab initio quantum chemical calculations support the observation. At the tetrahedrally coordinated (T) site, on the other hand, the tetrahedral O-T-O bond angle increases from 109.47° to 111.7(7)°, which generates a compressed tetrahedral geometry along the c-axis. As a result of the competing distortions between the elongated octahedron and the compressed tetrahedron, the a unit-cell parameter is shortened with respect to the c unit-cell parameter, giving a ca′ ratio (a′ = √2 a) slightly greater than unity as referred to cubic lattice (ca′ = 1.002). The ca′ value increases to 1.007 with pressure, suggesting further distortions of the elongated octahedron and compressed tetrahedron. [ABSTRACT FROM AUTHOR]

The water-gas shift reaction is studied using a series of Cu-Fe composite oxide catalysts, which were prepared by co-precipitation, deposition-precipitation, sol-gel, solid state reaction and mechanical mixing method, respectively. Distinct crystal structure and texture of the as-prepared catalysts were formed, and their reduction properties as well as surface basicities were modulated. The CO conversion in the water gas shift reaction is found to be correlation well with the Cu components in the temperature range of 200-350 °C, while the CO conversion is mainly controlled by Fe3O4 sites at temperature above 350 °C. The characterization results demonstrate that the formation of CuFe2O4 is ideal to obtain well dispersed Cu crystals; the weak basic sites are positive to the WGS reaction; and the strong interaction between copper and iron species can result in good Cu dispersion. The catalyst that was fabricated by the co-precipitation method, possesses the largest amount of CuFe2O4 and weak basic sites, as well as highly dispersed Cu crystals, thus showing the best catalytic activity and stability for the WGS reaction in our cases. [ABSTRACT FROM AUTHOR]

• The CuFe 2 O 4 /g-C 3 N 4 p-n junction photocatalysts were successfully prepared. • 8% CuFe 2 O 4 /g-C 3 N 4 composites displayed the highest photodegradation activity. • The CuFe 2 O 4 /g-C 3 N 4 p-n junction facilitates electron transfer and separation. • Charge separation in this composite follows a type II heterojunction composite. • H 2 O 2 through the photo-Fenton process enhances the photocatalytic activity of the composite. In this work, p-n type (type II) heterojunction (CuFe 2 O 4 /g-C 3 N 4) photocatalyst was used to purify methyl orange (MO), 4-chlorophenol (4-CP), and 4-nitrophenol (4-NP) in wastewater. The heterojunction photocatalysts with varying CuFe 2 O 4 mass concentrations were synthesized using a novel ultrasonic-assisted technique. Heterojunction formation between CuFe 2 O 4 and g-C 3 N 4 was verified using a high-resolution transmission electron microscope. Effective charge separation efficiency was identified through photocurrent and electrochemical impedance spectroscopy. The wrapped of CuFe 2 O 4 on the g-C 3 N 4 was also confirmed by X-ray photoelectron spectroscopy. According to Mott-Schottky analysis, p-type CuFe 2 O 4 has a lower flat band potential than n-type g-C 3 N 4. The results indicated that the composite of 8% CuFe 2 O 4 /g-C 3 N 4 displayed the highest photocatalytic activity in the presence of H 2 O 2 as an oxidant. It could strongly activate H 2 O 2 to degrade MO (∼98%) in 3 h under visible light irradiation. This remarkable enhancement of the photocatalytic activity could be assigned to the excellent electron transfer efficiency on the interface and the involvement of H 2 O 2 in the creation of additional hydroxyl radicals, which reinforce the photocatalytic performance. Additionally, this heterojunction composite showed the highest photocatalytic hydrogen production activity in the presence of methanol and Pt nanoparticles as cocatalyst. The feasible photocatalytic process as well as the enhanced photogenerated charge separation have also been thoroughly studied. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] A green technique for manufacturing CuFe2O4 was developed from industrial sludge. [•] The synthesized CuFe2O4 is fast and effective in removing P from polluted water. [•] The inner-sphere mechanism is importantly involved with P adsorption onto CuFe2O4. [•] The nano-CuFe2O4 can be rapidly recovered by a magnet because of its magnetism. [•] The results imply that 0.001 N NH4OH is sufficient for P desorption from CuFe2O4. [Copyright &y& Elsevier]

In this research, the heterogeneous photoelectron-Fenton-like process using copper ferrite (CuFe2O4) as catalyst was employed to remove p-nitrophenol (PNP). The CuFe2O4 catalyst was prepared by a co-precipitation process and characterised with X-ray fluorescence analysis, X-ray diffraction analysis and BET surface area. The results confirmed that CuFe2O4 was prepared successfully. Under the optimum conditions, namely 0.05 mol L−1 Na2SO4, the electrical potential of −0.6 V, pH 3.0 and 0.067 g L−1 CuFe2O4, 92.8% of 0.1 mM L−1, the PNP removal efficiency could reach 92.8% for 0.1 mM L−1 PNP after 180-min treatment. This technology can be applied for the treatment of organic compounds which are not readily biodegradable. [ABSTRACT FROM AUTHOR]

Highlights: [•] CuFe2O4 NPs were synthesized and characterized by XRD, FT-IR, AAS and TEM analysis. [•] Using catalyst, odorless production of thioethers and trithiocarbonates were done. [•] Magnetically recoverable and recyclable nanocatalyst. [•] The reactions are performed in polyethylene glycol as an eco-friendly media. [ABSTRACT FROM AUTHOR]

Solar water splitting has emerged as an urgent imperative as hydrogen emerges as an increasingly important form of energy storage. g-C 3 N 4 is an ideal candidate for photocatalytic water splitting as a result of the excellent alignment of its band edges with water redox potentials. To mitigate electron-hole recombination that has limited the performance of g-C 3 N 4 , we have developed a semiconductor heterostructure of g-C 3 N 4 with CuFe 2 O 4 nanoparticles (NPs) as a highly efficient photocatalyst. Visible-light-driven photocatalytic properties of CuFe 2 O 4 /g-C 3 N 4 heterostructures with different CuFe 2 O 4 loadings have been examined with two sacrificial agents. An up to 2.5-fold enhancement in catalytic efficiency is observed for CuFe 2 O 4 /g-C 3 N 4 heterostructures over g-C 3 N 4 nanosheets alone with the apparent quantum yield of H 2 production approaching 25%. The improved photocatalytic activity of the heterostructures suggests that introducing CuFe 2 O 4 NPs provides more active sites and reduces electron-hole recombination. The g-C 3 N 4 /CuFe 2 O 4 heterostructures furthermore show enhanced electrocatalytic HER activity as compared to the individual components as a result of which by making heterostructures g-C 3 N 4 with CuFe 2 O 4 increased the active catalytic surface for the electrocatalytic water splitting reaction. The enhanced faradaic efficiency of the prepared heterostructures makes it a potential candidate for efficient hydrogen generation. Nevertheless, the designed heterostructure materials exhibited significant photo- and electrocatalytic activity toward the HER, which demonstrates a method for methodically enhancing catalytic performance by creating heterostructures with the best energetic offsets.

• CuFe 2 O 4 modified activated carbon was used to remove H 2 S from humidified air. • Carbon with 20% CuFe 2 O 4 is practical material with 291.66 mg/mL volumetric capacity. • An important intermediate, FeOOH, was formed during the H 2 S removal. • Sulfur is the principal product of H 2 S oxidation on the modified activated carbon. • Desulfurization effect reduced by 7% after two cycles of thermal regeneration. A variety of CuFe 2 O 4 -based adsorbents with different active phase loadings were synthesized to remove H 2 S from humidified air at room temperature. The materials were characterized by adsorption of nitrogen, SEM-EDX, XPS, XRD, and TGA. According to the results, the activated carbon with 20 wt% CuFe 2 O 4 exhibited the best H 2 S adsorption performance, reaching 292 mg/mL (667 mg/g). Furthermore, the H 2 S adsorption capacity reduced by 7% after two cycles of thermal regeneration. During the desulfurization process, FeOOH formed as an intermediate played a catalytic role. The products comprised sulfide, elemental sulfur, and sulfates. Elemental sulfur was the predominant product. The H 2 S removal involved both reactive adsorption and catalytic oxidation. In addition to the chemical properties of the active phase, structural characteristics like pore volume also determined the adsorption capacity. Pore volume of less than 6 nm pores could enhance catalyst dispersion, provide adsorption centers and store the oxidation products. This study will offer novel insights for the efficient synthesis of metal oxide-based adsorbents and the extensive application of their reactive adsorption capacity at the nanoscale level. [ABSTRACT FROM AUTHOR]

This work is devoted to the systematic study of the optical and magneto-optical properties of sputter deposited CuFe2O4 thin films in the photon energy region between 2 and 5 eV using spectroscopic ellipsometry and magneto-optical Kerr spectroscopy. The spectral dependence of both the diagonal and off-diagonal elements of the permittivity tensor is determined. A complete picture about the electron transitions in CuFe2O4 is suggested in the frame of intervalence charge transfer and intersublattice charge transfer transitions. The effect of deposition conditions and post-deposition treatment in CuFe2O4 films upon the optical and magneto-optical properties is discussed. [ABSTRACT FROM AUTHOR]

In this paper CuFe2O4, nanocrystalline powders were prepared. Also, the supported Cu ferrite was obtained by impregnation of the supports with Cu and Fe nitrates solutions, for calcination temperature 450°C. The samples were characterized by X-ray powder diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR). In this investigation photocatalytic degradation of Acid red 206 in water was studied. The results show that the CuFe2O4 is an active photocatalyst. A first order reaction with k = 0.123 min-1 was observed. The effects of some parameters such as pH, amount of photocatalyst, initial concentration of dye were examined. [ABSTRACT FROM AUTHOR]

A recyclable catalytic system comprising magnetically separable CuFe2O4 nanoparticles in a poly(ethylene glycol) medium has been established as an inexpensive, nontoxic, environmentally benign system for the amination of aryl iodides with aqueous ammonia. A wide variety of aryl iodides underwent amination to afford the corresponding aryl amines in moderate to good yields. The catalytic system was recycled five times with consistent activity. [ABSTRACT FROM AUTHOR]

Abstract: Catalytic regioselective Friedel–Crafts acylation of an array of anisoles/arenes with various acid chlorides using 5–20mol% of magnetic nanopowder CuFe2O4 is reported. Unlike the conventional Friedel–Crafts reactions, which are catalyzed by moisture sensitive homogeneous catalysts/promoters, the nanopowder CuFe2O4 catalyst is moisture insensitive and the product/ketone-catalyst isolation is easily achieved using the magnetic properties of CuFe2O4. [Copyright &y& Elsevier]

CuFe2O4nanoparticles have been obtained by heat treatment of coprecipitation product, which were synthesis by reaction of Cu2+ions and Fe3+in alkaline condition. The morphology and microstructure of the synthesized urchin-like superstructures have been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the CuFe2O4nanoparticles were polycrystal with cubic jacobsite structure and a size distribution from 20 to 40 nm. Magnetic properties have been detected by a vibrating sample magnetometer at room temperature. The nanoparticles exhibited a ferromagnetic behavior with the coercive force (Hc) value of 86.83Oe, saturation magnetization (Ms) value of 37.98 emu/g and remanent magnetization (Mr) value of 2.68 emu/g. The IR spectrum of peak at 586 cm−1was corresponding to the vibration modes of CuFe2O4nanoparticles. [ABSTRACT FROM PUBLISHER]

Abstract: CuFe2O4 magnetic nanoparticles (MNPs) were prepared by sol–gel combustion method with copper and iron nitrates as metal precursors and citrate acid as a complex agent. The obtained CuFe2O4 MNPs were characterized by scanning electron microscopy, X-ray diffractometry, Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy and X-ray photoelectron spectroscopy. It was found that CuFe2O4 MNPs could effectively catalyze peroxymonosulfate (PMS) to generate sulfate radicals (SO4 −) to degrade tetrabromobisphenol A (TBBPA). The added TBBPA (10mgL−1) was almost completely removed (with a removal of 99%) in 30min by using 0.1gL−1 CuFe2O4 MNPs and 0.2mmolL−1 PMS. With higher addition of PMS (1.5mmolL−1), the degradation yielded a TOC removal of 56% and a TBBPA debromination ratio of 67%. The effect of catalyst calcination temperature, catalyst load, PMS concentration and reaction temperature was investigated on the catalytic activity of CuFe2O4 MNPs. The highly catalytic activity of CuFe2O4 MNPs possibly involved the activation of PMS by both Cu(II) and Fe(III) in CuFe2O4 MNPs. Based on intermediate detections, the degradation pathway of TBBPA in the CuFe2O4 MNPs/PMS system was proposed. [Copyright &y& Elsevier]

Abstract: Magnetic nano-particles CuFe2O4 were successful manufactured from industrial sludge by combination of acid leaching, chemical exchange, and ferrite process. For the first time these recycled nano-particles were used as adsorbent to investigate the kinetics and thermodynamics for adsorption of Cd in aqueous solutions. These experimental results showed that Cd2+ adsorption efficiency increased from 0.85 to 99.9% when pH increased from 2 to 6. The maximum adsorption capacity of Cd2+ was found to be 17.54mgg−1 under the conditions at pH 6.0, contact time 30min, and temperature 318K. The pseudo-second-order kinetic model provides the best correlation with the experimental data compared to the pseudo-first-order model. The Langmuir model yields a better fitting than the Freundlich model for Cd2+ adsorption on CuFe2O4 nano-particles under investigated temperatures. The thermodynamic constants of the adsorption process were evaluated, ΔG°, ΔH° and ΔS° is −6.05kJmol−1 (at 318K), 0.71kJmol−1, and 4.53Jmol−1 K−1, respectively. These results imply that Cd2+ adsorption onto CuFe2O4 is feasible, spontaneous and endothermic in nature. [Copyright &y& Elsevier]