► A novel ZnFe2O4@ZnO core–shell photocatalyst was successfully prepared. ► The photocatalyst exhibited higher photocatalytic activity than pure ZnO. ► The composite photocatalyst inhibited the ...photocorrossion of ZnO to some extent. ► The novel photocatalyst could be easily separated by external magnetic field.
Magnetically separable ZnFe2O4@ZnO nanoparticles with enhanced photocatalytic activity were successfully synthesized by two steps. First, ZnFe2O4 nanoparticles (NPs), which served as seeding materials, were synthesized using a solvothermal method. Second, wurtzite ZnO was coated on the ZnFe2O4 particle surfaces on the basis of a chemical precipitation method. The as-prepared samples were characterized with X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM) and Energy-dispersive X-ray spectroscopy (EDS). Photodegradation experiments of the samples were carried out by choosing Methylene Blue (MB) as a model target under UV irradiation with homemade photocatalytic apparatus. The results indicated that the obtained core–shell ZnFe2O4@ZnO NPs exhibited higher photocatalytic activity than pure ZnO. In addition, when the molar ratio of ZnFe2O4 to ZnO was 1:10, the obtained product showed the highest photocatalytic activity. Furthermore, the core–shell ZnFe2O4@ZnO NPs could be conveniently separated by using an external magnetic field and the photocorrosion of ZnO was inhibited to some extent.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► Flower-like ZnO structures are prepared by a facile hydrothermal method. ► Alkaline environments are responsible for the morphological transition. ► Flower-shaped ZnO samples exhibit the highest ...photocatalytic activity. ► The growth mechanism and photodegradation process are proposed.
Flower-like ZnO structures with high photocatalytic performance were successfully synthesized via a facile hydrothermal method. Alkaline environment played a critical role during the morphological transformation. When the molar ratio of Zn(CH3COO)2·2H2O to NaOH was set as 1:8 in the presence of triethanolamine (TEA), and the molar ratio of Zn2+ to TEA was 1:9, the flower-like ZnO product was produced. The hexagonal sphere-like, oblate-like, and hexagonal biprism-like samples were also obtained by adjusting the molar ratio of Zn2+ to NaOH as 1:2, 1:5 and 1:12 with the presence of invariable amount of TEA, respectively. The prepared ZnO products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) surface area. Photodegradation experiments of the samples were carried out by choosing Methylene Blue (MB) as a model target under UV irradiation with homemade photocatalytic apparatus. Among these products, flower-shaped samples exhibited the highest photocatalytic activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In order to develop multifunctional quaternary ammonium salts and explore their advantages as modifiers for wastewater treatment, castor oil-based quaternary ammonium salts were synthesised and ...subsequently used as modifiers for attapulgite treatment. The structures of untreated and treated attapulgite were compared by Fourier transform infrared spectra and X-ray diffraction. The mechanism of modification was speculated. Various factors such as the amount of modified attapulgite, temperature and pH were also investigated in the batch experiments on the removal rates of acetone and phenol from wastewaters. The synthesis conditions were set as follows: the reaction temperature was 80 °C, the reaction time was 8 h, the molar ratio of castor oil to N,N-dimethyl-1,3-propanediamine was 1:5, the catalyst was 6% NaOH and the product yield was about 64.72%. The grafting rate of the castor oil-based quaternary ammonium salt was about 99.6% when the amount of modifier was 0.69 g per 5 g of attapulgite, the ultrasound treatment time was 11 min and the pH was 5. The quaternary ammonium salt was only associated with the surface of attapulgite and did not change the rod-like crystal structure of the silicate. The modified attapulgite is much more fibrous and exhibits a good distribution of crystal bundles. The removal rates were found to be less favourable under strongly acidic and strongly alkaline conditions. Under suitable conditions, for 50 mL industrial wastewaters (phenol: 100-160 mg/L; acetone: 680-800 mg/L), the amount of modified attapulgite was 1 g, the temperature was 80 °C and the pH was 7, and the maximum removal rates of acetone and phenol after 80 min reached about 65.71% and 78.72%, respectively, which were higher than those of ATP.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The present work reports on the synthesis of ZnO photocatalysts with different Co-doping levels via a facile one-step solution route. The structural and optical properties were characterized by ...powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and UV-Vis diffuse reflectance spectra. The morphology of Co-doped ZnO depends on the reaction temperature and the amount of Co and counter-ions in the solution. Changes with the c-axis lattice constant and room temperature redshift show the replacement of Zn with Co ions without changing the wurtzite structure. Photocatalytic activities of Co-doped ZnO on the evolution of H
and the degradation of methylene blue (MB) reduce with the doping of Co ions. As the close ionic radii of Co and Zn, the reducing photocatalytic activity is not due to the physical defects but the formation of deep bandgap energy levels. Photocurrent response experiments further prove the formation of the recombination centers. Mechanistic insights into Co-ZnO formation and performance regulation are essential for their structural adaptation for application in catalysis, energy storage, etc.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
T
he adsorption method is considered to be one of the most promising organic pollutants emission reduction strategies. The design and synthesis of high-performance porous adsorbents are one of the ...most important but challenging works. In this work, we constructed a new class of porous molecular cage switches by a simple reaction using phenolphthalein as the raw material. The molecular cage switches displayed interesting on-off behavior towards organic guests, which is highly responding to organic pollutants with rapid color change and is also able to adsorb these organic pollutants through an open-to-close pathway. This molecular cage switch also has excellent regenerative cycling properties and water resistance, which is expected to be employed in the handling of organic pollutants in the future.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An all-solid-state Bi2WO6/Au/CdS Z-scheme system was constructed for the photocatalytic reduction of CO2 into methane in the presence of water vapor. This Z-scheme consists of ultrathin Bi2WO6 ...nanoplates and CdS nanoparticles as photocatalysts, and a Au nanoparticle as a solid electron mediator offering a high speed charge transfer channel and leading to more efficient spatial separation of electron-hole pairs. The photo-generated electrons from the conduction band (CB) of Bi2WO6 transfer to the Au, and then release to the valence band (VB) of CdS to recombine with the holes of CdS. It allows the electrons remaining in the CB of CdS and holes in the VB of Bi2WO6 to possess strong reduction and oxidation powers, respectively, leading the Bi2WO6/Au/CdS to exhibit high photocatalytic reduction of CO2, relative to bare Bi2WO6, Bi2WO6/Au, and Bi2WO6/CdS. The depressed hole density on CdS also enhances the stability of the CdS against photocorrosion.
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► A simple aqueous solution process has been applied to prepare zinc oxide particles. ► This novel method exempts traditional calcinations. ► Various zinc oxide particles are ...obtained.
TEA and NaOH are applied to transform layered basic zinc acetate into zinc oxide particles by a simple aqueous solution process (<100°C). Zinc oxide with different morphologies, including dumbbells, earthnuts, ellipsoids and hexagonal pillars, are obtained by carefully controlling the amounts of sodium hydroxide, triethanolamine, and reaction temperature. Field emission scanning electron microscope images, X-ray powder diffraction patterns, X-ray photoelectron spectroscopy spectra and room-temperature photoluminescence spectra are used to characterize final products. Furthermore, a possible growth mechanism is discussed in this paper. This easy procedure for zinc oxide fabrication offers the possibility of a generalized approach to the production of metal oxide with tunable morphology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Novel well-defined cuprous oxide (Cu2O) thin films are synthesized on indium-doped tin oxide (ITO) covered glass substrates by electrochemical deposition, with cationic surfactant, cetyl ...trimethylammonium bromide (CTAB) as shape controlled agent. The effects of the quantity of CTAB, the temperature and concentration of electrolyte were studied. It was shown that the morphology evolved from flower-leaves to spheres with increasing quantity of CTAB, which indicated that the morphology varied with the CTAB concentration. Furthermore, the optical properties of Cu2O films was investigated and found that Cu2O film composed of shagginess spheres have better photoluminescence (PL) properties. Also, the Cu2O film can be used as substrates for functional applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Self-assembled ZnO quasi-microspheres constructed of tunable building blocks have been grown directly through a facile liquid process. The effects of preparation parameters, such as the amounts of ...triethanolamine (TEA) and types of zinc counterions (SO
4
2−, CH
3COO
−), on the morphology of building blocks (BLs) have been examined. Experimental data show that TEA has played a dual key function in the self-assembly process; namely, one is to regulate the morphology of BLs, and the other is to induce the oriented attachment of these particles. A rational formation mechanism is proposed on the basis of detailed results of FESEM, TEM and zeta potentials tests. The overall formation of 3-D self-assembled ZnO quasi-microspheres can be summarized as: (a) growth of ZnO building blocks; (b) preassembly of these BLs into small aggregates; (c) further assembly of these aggregates to form special 3-D architectures. XRD and Raman spectra show that the self-assembled quasi-microspheres have wurtzite structures. Room-temperature PL spectra indicate that they have a potential application as ultraviolet emitters. This work presents a simple route using common organic molecules, TEA, as “growth modifiers”, to the fabrication of novel 3-D self-assembled ZnO superstructures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The photocatalytic reduction of CO2 over Ag/TiO2 composites prepared with a simple silver mirror reaction method was investigated under UV-visible irradiation in both gas-phase (CO2 + water vapor) ...and aqueous solution (CO2-saturated NaHCO3 solution) systems. The as-prepared Ag/TiO2 nanocomposite exhibits efficient photocatalytic activity due to the surface plasmonic resonance and electron sink effect of the Ag component, which was found to be closely related to the size and loading amount of Ag. The rapid silver method is effective at curbing the size of Ag, so photocatalytic activity can be improved. Diverse organic chemical products were detected, including mainly methane and methanol as well as a small amount of C2 and C3 species such as acetaldehyde and acetone. Possible photocatalytic mechanisms were proposed. This artificial photosynthesis process may give a prosperous route to the removal of CO2 while simultaneously converting CO2 to valuable fuels based on highly efficient photocatalysts.
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