Preparation of CdS–TiO2/Fe3O4 photocatalyst and its photocatalytic properties

The CdS modified TiO₂/Fe₃O₄ photocatalysts were prepared by sol–gel and immersion methods. The morphological, structural and optical properties of as-prepared samples were characterized by X-ray diffraction (XRD), UV–Vis absorption spectra, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The TEM observation showed that the surface of magnetite particles (Fe₃O₄) were coated by CdS–TiO₂ layer as loose clusters, and average diameter of composites particles was about 250 nm. UV–Vis absorption spectra indicated that CdS–TiO₂/Fe₃O₄ composites had pronounced red-shift compared with that of TiO₂/Fe₃O₄. The CdS–TiO₂/Fe₃O₄ composites exhibit higher photocatalytic activity than pure TiO₂ and TiO₂/Fe₃O₄ for the degradation of Reactive Brilliant Red X-3B dye (X-3B) aqueous solution under simulated sunlight, and the optimum content of CdS is 1.0 % (mol ratio of CdS to TiO₂). In addition, a gradual loss of photocatalytic activity can be observed in reusability test of CdS–TiO₂/Fe₃O₄ composites, and degradation of X-3B reached still to 78.9 % after five runs.     

Facile and mass production synthesis of β-NaYF4:Yb3+, Er3+/Tm3+ 1D microstructures with multicolor up-conversion luminescence

Well defined, pure hexagonal-phased NaYF(4):Yb(3+),Er(3+)/Tm(3+) microtubes and microrods were first prepared by a facile and mass production molten salt method without using any surfactant, which offers a new alternative in synthesizing such materials and opens the possibility to meet the increasing commercial demand.     

Magnetically recoverable Cu2O/Fe3O4 composite photocatalysts：Fabrication and photocatalytic activity

A magnetically separable Cu2O/Fe3O4 magnetic composite photocatalyst was synthesized in large quantities by a fast and simple route. The as-prepared photocatalysts were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray photoelectron spectroscopy （XPS） and X-ray diffraction （XRD）. Furthermore, the Cu2O/Fe3O4 composite photocatalysts were tested using methyl orange （MO） degradation reaction under visible light irradiation （100 mW/cm2） and demonstrated to have a high photocatalytic efficiency toward the decomposition of MO under visible light irradiation with good recyclability.     

Novel synthesis of Z-scheme α-Bi2O3/g-C3N4 composite photocatalyst and its enhanced visible light photocatalytic performance: Influence of calcination temperature

In this study, α-Bi₂O₃/g-C₃N₄ nanocomposite with direct Z-scheme was successfully prepared through calcination of BiOCOOH/g-C₃N₄ precursor at different temperature. Meanwhile, the effect of calcination temperature on the physicochemical properties of α-Bi₂O₃/g-C₃N₄ was studied. All results confirmed that calcination temperature greatly influences structural, morphology, surface states, photoelectrochemical property and photocatalytic (PC) performance of α-Bi₂O₃/g-C₃N₄ composite. Furthermore, the α-Bi₂O₃/g-C₃N₄ composite was applied as photocatalyst to degrade amido black 10B dye under visible light irradiation. It was found that the composite synthesized at 400 °C exhibited the highest PC performance due to the intense visible light absorbance and high separation efficiency of electron and hole pairs. Besides, the possible PC mechanism was proposed that the photo-generated charge carrier migration in α-Bi₂O₃/g-C₃N₄ photocatalyst followed a Z-scheme structure. Finally, the stability test also manifest that the α-Bi₂O₃/g-C₃N₄ composite photocatalyst has good stability and reusability, which was a promising candidate for wastewater treatment.     

Preparation and characterization of SO4 2−/Fe2O3–TiO2–Nd2O3 catalyst

This paper reports on the preparation of SO₄ ^2?/Fe₂O₃–TiO₂–Nd₂O₃ (SFTN) by combustion method. The effect of Nd content on catalytic activity was investigated. The prepared materials doped and undoped by Nd were compared by means of TG-DTG, XRD, FT-IR, NH₃-TPD and TEM techniques. Results indicated that the introduction of Nd improved the catalytic activities of the catalysts. Catalytic activity of SFTN was the highest with 98.3 % menthol conversion when Nd content was at 2 wt%. The introduction of Nd stabilized the coordination bond between the sulfate irons and the metallic oxides, helping in the formation of solid acid sites, enhancing the dispersion of catalyst particles, and inhibiting the growth of catalyst particles under heating.     

Synthesis and Characterization of Novel Magnetic Poly(urethane-imide)/Fe3O4@SiO2–NH2 Nanocomposites

Russian Journal of Applied Chemistry - Poly(urethane-imide)/Fe3O4@SiO2–NH2 nanocomposites were synthesized by the reaction of 4,4′-diphenylmethane diisocyanate (MDI), polypropylene...     

Sol–gel preparation and photocatalytic performance of TiO2/SrAl2O4: Eu2+, Dy3+ toward the oxidation of gaseous benzene

It has been found that the photocatalytic activity of TiO₂ toward the decomposition of gaseous benzene can be greatly enhanced by loading TiO₂ on the surface of SrAl₂O₄: Eu²⁺, Dy³⁺ using sol–gel technology. The prepared photocatalyst was characterized by BET, XRD, and XPS analyses. XRD results reveal that the peaks of titania in either rutile or anatase form are not detected by XRD in the 2θ region from 20° to 50°. The binding energy values of Ti 2p of pure TiO₂ are 458.90 and 464.60 eV, while for TiO₂/SrAl₂O₄: Eu²⁺, Dy³⁺, the binding energy values of Ti 2p are 458.50 and 464.20 eV. The results indicate that the optimum loading of TiO₂ is 1 wt% and TiO₂/SrAl₂O₄: Eu²⁺, Dy³⁺ (1 wt%) demonstrates 1.4 times the photocatalytic activity of that of pure TiO₂, but the underlying mechanism of SrAl₂O₄: Eu²⁺, Dy³⁺ in the photocatalytic reaction remains to be unraveled.     

α-Fe2O3 nanoflowers: synthesis,characterization, electrochemical sensing and photocatalytic property

Nanoflower structured α-Fe₂O₃ was synthesized by adding hexamine to an aqueous solution of ferrous sulphate followed by drying and annealing at 600 °C for 6 h. X-ray diffraction analysis, Fourier-transformed infrared spectroscopy, Raman and DRS UV–visible absorption spectroscopy showed the formation of α-Fe₂O₃ with good crystalline nature. Field emission-scanning electron microscopy investigation revealed that the α-Fe₂O₃ has flower-like morphology, which is composed of nanorods. Cyclic voltammetry and chronoamperometry were used to investigate their electrochemical sensing property towards uric acid (UA). α-Fe₂O₃ exhibited enhanced sensing behavior with respect to that of bare GCE. Additionally, the α-Fe₂O₃ nanoflowers exhibit better photocatalytic activity of up to 71.7 % against rhodamine B (RhB) in short time of 60 min under visible light irradiation. It is found that the smaller crystallite size and flower-like morphology play a vital role in allowing an interaction between α-Fe₂O₃ and UA or RhB dye which enhances both the electrochemical sensing and photocatalytic activity.     

Synthesis,characterization and visible-light photocatalytic activity of TiO2–SiO2 composite modified with zinc porphyrins

Three types of silica gel supported titanium dioxide particles immobilizing Zn(II) carboxylphenyl porphyrins appending p-CH₃, p-H and p-Cl phenyl substituents (designated as ZnMP–TiO₂–SiO₂, ZnPP–TiO₂–SiO₂ and ZnCP–TiO₂–SiO₂, respectively) have been synthesized and characterized using SEM, XRD, IR, AFS, DRS, UV–Vis, XPS and TG. The photodegradation of α-terpinene in aqueous suspension was used to determine the photocatalytic activity of TiO₂–SiO₂ samples which had been impregnated with Zn(II) porphyrins, as sensitizers. The experimental results confirmed that the photocatalytic activitys of these composites are much higher than those of the nonmodified TiO₂–SiO₂ under visible light irradiation and follow the order of ZnMP–TiO₂–SiO₂ > ZnPP–TiO₂–SiO₂ > ZnCP–TiO₂–SiO₂.     

Preparation of a visible light-driven Bi2O3–TiO2 composite photocatalyst by an ethylene glycol-assisted sol–gel method,and its photocatalytic properties

A visible light-driven Bi₂O₃–TiO₂ composite photocatalyst was prepared by an ethylene glycol-assisted sol–gel method in which ethylene glycol acted as a polycondensation agent to capture metal ions by reacting with bismuth and titanium sources via a complex polycondensation pathway. The photocatalyst was characterized by X-ray photoelectron spectroscopy, X-ray diffraction, acquisition of N₂ adsorption–desorption isotherms, transmission electron microscopy, and UV–visible diffuse reflectance spectroscopy. The results revealed that the Bi₂O₃–TiO₂ composite was of smaller particle size, greater specific surface area, and had stronger absorbance in the visible light region than pure TiO₂. The photocatalytic activity of the as-prepared catalyst was evaluated by degradation of rhodamine B under visible light irradiation (λ > 400 nm); the as-prepared Bi₂O₃–TiO₂ composite was substantially more active than pure TiO₂. This was ascribed to the high surface area and the heterojunction structure.     

Luminescent core–shell Fe3O4@Gd2O3:Er3+, Li+ composite particles with enhanced optical properties

Bifunctional magneto-optical nanocomposites with Fe₃O₄ nanoparticles as a core and erbium and lithium codoped gadolinium (Gd₂O₃:Er³⁺, Li⁺) as the shell were synthesized successfully using a simple urea homogeneous precipitation method. The fabricated Fe₃O₄@Gd₂O₃:Er³⁺, Li⁺ particles were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy and quantum design vibrating sample magnetometry. The upconversion emission intensity was enhanced significantly comparing to that without Li⁺ ions. These bifunctional composites are expected to be potentially applied for drug delivery, cell separation and bioimaging.     

Synthesis and characterization of a novel Fe3O4@SiO2/bipyridinium dichloride nanocomposite and its application as a magnetic and recyclable phase-transfer catalyst in the preparation of β-azidoalcohols, β-cyanohydrins,and β-acetoxy alcohols

β-Azidoalcohols, β-cyanohydrins, and β-acetoxy alcohols have been synthesized in the presence of a Fe₃O₄@SiO₂/bipyridinium nanocomposite (Fe₃O₄@SiO₂/BNC) as a novel magnetic and recyclable phase-transfer catalyst (PTC) in water. The catalyst was characterized with FT–IR, SEM, XRD, VSM, and TGA. This methodology offers several advantages, including easy work-up procedure, excellent regioselectivity, high yields, short reaction times, recyclable catalyst, easy separation of the catalyst through an external magnet and eco-friendly procedure.     

Synthesis, characterization, infrared studies, and thermal analysis of Mn0.6Zn0.4Fe2(C4H2O4)3·6N2H4 and its decomposition product Mn0.6Zn0.4Fe2O4

Manganese zinc ferrous fumarato–hydrazinate precursor, Mn_0.6Zn_0.4Fe₂(C₄H₂O₄)₃·6N₂H₄ was synthesized for the first time and characterized by chemical analysis, infrared spectral studies, and thermal analysis. Infrared studies show band at 977 cm^?1 indicating bidentate bridging nature of the hydrazine in the complex. Thermogravimetric (TG) studies show two steps dehydrazination followed by two steps total decarboxylation. The precursor on touching with burning splinter undergoes self propagating autocatalytic decomposition yielding ultrafine Mn_0.6Zn_0.4Fe₂O₄. XRD studies confirms single phase formation as well as nanosize nature of “as prepared” Mn_0.6Zn_0.4Fe₂O₄. The saturation magnetization of the “as prepared” Mn_0.6Zn_0.4Fe₂O₄ was found to be 31.46 emu gm^?1, which is lower than the reported, confirms the ultrafine nature of the oxide.     

Synthesis,characterization and photocatalytic properties of Mg1−xZnxAl2O4 spinel nanoparticles

Mg_1−xZn_xAl₂O₄ spinel nanoparticles with x = 0, 0.05, 0.10, 0.15 and 0.20 were prepared via the chemical coprecipitation method. The obtained samples were characterised by thermal gravimetric and differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, UV–Vis diffuse reflection spectrum, transmission electron microscopy and ²⁷Al MAS-NMR spectroscopy. Mg_1−xZn_xAl₂O₄ spinel powders with the mean crystallite size of around 11 nm–14 nm were obtained. The crystallinity of the MgAl₂O₄ samples increases with the increase in the calcination temperature. At the same calcination temperature, higher amount of Zn²⁺ substitution leads to the higher level of crystallinity, but has no apparent influence on the mean crystallite size of the samples. The photocatalytic activity of the obtained Mg_1−xZn_xAl₂O₄ spinel nanoparticles was evaluated by monitoring the degradation of methylene blue under UV light. The degradation rates of methylene blue using the MgAl₂O₄ nanoparticles prepared at the calcination temperatures of 700 °C and 800 °C are much higher than those prepared at 900 °C and 1000 °C. The photocatalytic activities of the spinel powders with lower level of Zn²⁺ substitution such as Mg_0.95Zn_0.05Al₂O₄ are inferior to that of MgAl₂O₄. Results of ²⁷Al MAS-NMR spectroscopy analysis and the first principle total density of state calculations reveal that this is probably due to the substitutions of Zn²⁺ decreasing the degree of Al³⁺ ions inversion over the sites of tetrahedral and octahedral coordination. With the increase in the amounts of Zn²⁺ substitution, the effects of Zn²⁺ additions on the photocatalytic activities become gradually predominant, leading to the increases in the degradation rates. The methylene blue degraded by 99% within 4 h using the Mg_0.8Zn_0.2Al₂O₄ spinel powders.     

Synthesis and characterization of magnetic dichromate hybrid nanomaterials with triphenylphosphine surface modified iron oxide nanoparticles (Fe3O4@SiO2@PPh3@Cr2O72−)

In this study, a new magnetic hybrid nanomaterials Fe₃O₄@SiO₂@PPh₃@Cr₂O₇²⁻ is introduced. First, the magnetic Fe₃O₄ nanoparticles have been synthesized by co-precipitation method. Then, tetraethyl orthosilicate has been used for production of core–shell nanoparticles Fe₃O₄@SiO₂. The core–shell magnetic nanoparticles system Fe₃O₄@SiO₂ functionalization was synthesized using (3-chloropropyl) trimethoxysilane and triphenylphosphine and the cationic part was prepared for immobilization of anionic part of the Cr (VI) catalysts including Cr₂O₇²⁻. After immobilization of the catalyst, its structure was detected by using Fourier transform infrared (FT-IR), solid state UV–Vis, elemental analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD) and the particle size and morphology were elaborated by scanning electron microscope (SEM) and XRD. Magnetism properties were quantified by vibrating sample magnetometer (VSM).     

Facile synthesis of nanoscaled α-Fe2O3, CuO and CuO/Fe2O3 hybrid oxides and their electrocatalytic and photocatalytic properties

A facile and easily controlled route was designed to synthesize nano-structured Fe₂O₃, CuO, and CuO/Fe₂O₃ hybrid oxides with different Cu/Fe molar ratios via a hydrothermal procedure. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and field-emission scanning electron microscopy (FE-SEM). The results showed that the morphologies of the samples changed with different Cu/Fe ratios. The electrocatalytic properties of the samples modified on a glassy carbon electrode for p-nitrophenol reduction in a basic solution were investigated. The results indicated that CuO/Fe₂O₃ hybrids with lower Cu/Fe ratio exhibited higher electrocatalytic activity. The photocatalytic performances of the samples for methyl orange degradation with assistance of oxydol under irradiation of visible light were studied. The results revealed that CuO/Fe₂O₃ hybrids with higher Cu/Fe ratio showed efficient photocatalytic activity.