Synthesis of dual Z-scheme photocatalyst ZnFe2O4/PANI/Ag2CO3 with enhanced visible light photocatalytic activity and degradation of pollutants

The ZnFe₂O₄/PANI/Ag₂CO₃ photocatalyst was synthesized by the co-precipitation method. The composition, morphology and optical properties of the synthesized photocatalyst were characterized. Compared with pure Ag₂CO₃, ZnFe₂O₄, PANI/Ag₂CO₃ and ZnFe₂O₄/Ag₂CO₃, ZnFe₂O₄/PANI/Ag₂CO₃ has the best photocatalytic ability of bisphenol A can reach 86.36% under 40 min of light, and it has a certain ability to be reused. At the same time, after 1 h of light, the degradation rate of Nitrobenzene can reach 90%. The reason for the increased catalytic ability of ZnFe₂O₄/PANI/Ag₂CO₃ can be attributed to the extended absorption capacity of the visible light region and the efficient separation of electron-hole pairs.     

Fabrication of magnetic ZnO/ZnFe2O4/diatomite composites: improved photocatalytic efficiency under visible light irradiation

Journal of Materials Science: Materials in Electronics - The magnetic recoverable ZnO/ZnFe2O4/diatomite (ZZFDT) composite was synthesized by hydrothermal-precipitation method. The structure,...     

Fabrication of anion exchanger resin/nano-CdS composite photocatalyst for visible light RhB degradation

A novel nanocomposite photocatalyst, D201-CdS beads (0.70-0.80 mm in diameter), was fabricated for visible light (λ > 420 nm) photodegradation of Rhodamine B (RhB). Sphalerite CdS nanoparticles (5-15 nm) were distributed within the outer layer of D201 for favorable visible light permeation. Ultraviolet-visible spectral changes of RhB solution indicated that efficient RhB photodegradation was achieved by D201-CdS under visible light irradiation. More attractively, negligible photocorrosion of the hybrid catalyst D201-CdS was demonstrated by the constant photodegradation efficiency and negligible CdS leaching during five-cycle batch runs. Besides the higher stability, D201-CdS is superior to CdS in terms of separation. The used nanocomposite can be readily separated from solutions by a simple filtration while a high speed centrifugation is needed for the separation of CdS. The above results suggested that the resultant D201-CdS nanocomposite catalyst is promising for practical application in environmental remediation.     

Preparation of visible light responsive g-C3N4/H-TiO2 Z-scheme heterojunction with enhanced photocatalytic activity for RhB degradation

The development of high-efficiency heterojunction with improved photocatalytic property is regarded as a promising way to decontaminate wastewater. In this study, Z-Scheme g-C₃N₄/H-TiO₂ heterojunctions with different proportions were synthesized. The photocatalytic degradation of rhodamine B (RhB) was studied under visible light irradiation. Among them, 10% g-C₃N₄/H-TiO₂ photocatalyst had the best performance, and the degradation rate of RhB was 65% within 120 min. In addition, 10% g-C₃N₄/H-TiO₂ photocatalyst had high stability, and its photocatalytic activity did not decrease significantly after four cycles. Through photocurrent analysis, it is found that the photogenerated carriers have obviously excellent separation and transfer characteristics, which makes the 10% g-C₃N₄/H-TiO₂ photocatalyst have good degradation performance. Electron paramagnetic resonance (ESR) experiments showed that ·OH and ·O₂^? were active radicals during degradation.

     

Construction of novel TiO_2/Bi_4Ti_3O_(12)/MoS_2 core/shell nanofibers for enhanced visible light photocatalysis

TiO2/Bi4 Ti3 O12 hybrids have been widely prepared as promising photocatalysts for decomposing organic contaminations.However,the insufficient visible light absorption and low charge separation efficiency lead to their poor photocatalytic activity.Herein,a robust methodology to construct novel TiO2/Bi4 Ti3 O12/MoS2 core/shell structures as visible light photocatalysts is presented.Homogeneous bismuth oxyiodide(BiOI) nanoplates were immobilized on electrospun TiO2 nanofiber surface by successive ionic layer adsorption and reaction(SILAR) method.TiO2/Bi4 Ti3 O12 core/shell nanofibers were conveniently prepared by partial conversion of TiO2 to high crystallized Bi4 Ti3 O12 shells through a solid-state reaction with BiOI nanoplates,which is accompanied with certain transition of TiO2 from anatase to rutile phase.Afterwards,MoS2 nanosheets with several layers thick were uniform decorated on the TiO2/Bi4 TiO3 O12 fiber surface resulting in TiO2/Bi4 Ti3 O12/MoS2 structures.Significant enhancement of visible light absorption and photo-generated charge separation of TiO2/Bi4 Ti3 O12 were achieved by introduction of MoS2.As a result,the optimized TiO2/Bi4 Ti3 O12/MoS2-2 presents 60% improvement for photodegrading RhB after 120 min irradiation under visible light and 3 times higher of apparent reaction rate constant in compared with the TiO2/Bi4 Ti3 O12.This synthetic method can also be used to establish other photocatalysts simply at low cost,therefore,is suitable for practical applications.     

B掺杂g-C3N4的一步合成及可见光下降解RhB和TC研究

为研究非金属离子掺杂对g-C₃N₄光催化性能的影响,以三聚氰胺和硼酸为前驱体,采用一步煅烧法制备了B掺杂g-C₃N₄光催化剂。罗丹明B(RhB)的可见光降解实验表明,当三聚氰胺和硼酸的添加比例(质量比)为10∶0.05(0.05BCN)时显示出最好的光催化性能,表现为光照RhB 30 min降解率高达100%,远高于纯g-C₃N₄(38%)。同时,四环素(TC)降解9 min达到100%,降解速率为纯g-C₃N₄的2.09倍。基于结构表征和光学性能测量,高光催化性能可归因于B原子掺杂替代引起的带隙调制。B掺杂不仅减小了带隙且可能在带隙中引入杂质态能级,这些都能导致可见光吸收的增强和光生载流子复合的抑制,从而大大提高了光催化性能。本工作提供了一种原子级水平获取非金属元素修饰g-C₃N₄纳米片的方法,该材料可作为一种在可见光下具有良好稳定性的RhB降解光催化剂。     

Magnetic Properties of Nanocrystalline CoFe2O4/ZnFe2O4 Bilayers

Nanocrystalline spinel CoFe₂O₄/ZnFe₂O₄ bilayers were deposited by the pulsed laser deposition technique on amorphous fused quartz substrate at different substrate temperatures ranging from room temperature to 750?°C. The magnetic properties of the bilayers and of the single layer films deposited in identical conditions were studied at 300?K and at 10?K. Magnetic properties of the bilayers, in general, were found to be in between the individual values of the single layers. Magnetic measurements at 10?K clearly showed a two stepped magnetic hysteresis loop corresponding to the switching of the magnetic moments of the soft ZnFe₂O₄ and the hard CoFe₂O₄ layers. A study was also carried out by changing the thickness of ZnFe₂O₄ layer in the bilayer. This study showed that the magnetic properties of the bilayers even at room temperature can be controlled to some extent by changing the thickness of the soft ZnFe₂O₄ layer while maintaining a low substrate temperature of 350?°C.     

Preparation of stone-shaped CuBi2O4 by solid phase method and H2O2 assisted visible light degradation for orange II

CuBi₂O₄ is widely used in photocatalytic degradation for pollutants in water due to its strong visible light response characteristics, excellent chemical stability, non-toxic, and low cost. Here, stone-shaped CuBi₂O₄ was prepared with CuO and Bi₂O₃ as raw materials by high temperature solid phase. The effect of calcined temperature and time on the product was discussed. This material was analyzed and discussed by XRD, SEM, XPS, and DRS, and the visible light activity of degradation for Orange II was explored. The results showed that the absorption edge of prepared CuBi₂O₄ expands to the visible region, and the band gap was about 1.77 eV. The photocatalytic degradation rate of Orange II was 42.6% under the optimal conditions. After H₂O₂ assisted, the degradation rate was more than 2 times, and repeated experiments verified that the prepared catalysts had high stability. Finally, a reasonable mechanism of H₂O₂ assisted degradation enhancement is proposed. This work gives new ideas for the preparation of new and efficient catalytic materials.

     

Electrospun MnFe2O4 nanofibers: Preparation and morphology

The composite fibers were prepared by an electrospinning the solutions mixed manganese ferrite sol with polyvinyl acetate (PVAc). The manganese ferrite sol was obtained from manganese(II) nitrate and iron(III) nitrate nonahydrate molecular precursor based on a sol–gel procedure. Manganese ferrite (MnFe₂O₄) nanofibers were prepared by calcining the above composite fibers in air at 400, 600 and 800 °C, respectively. The obtained nanofibers were characterized by SEM, FT-IR, XRD, and extended X-ray absorption fine structure (EXAFS). After being calcined at 800 °C, the fibers became continuous crystallites as a result of the complete decomposition of PVAc. The morphology of manganese ferrite was found to be cubic spinel structure containing eight oxygens and 12 metal atoms in the unit cell, referred from the results of EXAFS. Also, the magnetic properties of the calcined samples were characterized by using a vibrating sample magnetometer (VSM).     

Synergic effect of Sn-doped TiO2 nanostructures for enhanced visible light photocatalysis

Journal of Materials Science: Materials in Electronics - In the recent years, metal oxides have attracted more interest for researchers because of their applications in energy and...     

纳米Bi_2O_3的制备及其可见光催化活性

采用共沉淀法制备纳米Bi_2O_3,并将其应用于光催化,研究不同热处理温度下制备的Bi_2O_3的光催化降解甲基橙的活性。通过扫描电子显微镜、X射线衍射、紫外-可见吸收光谱和荧光光谱表征Bi_2O_3的形貌、结构、光学及光催化活性。结果表明:Bi_2O_3的光催化活性与热处理温度有关,热处理温度为400℃时,合成的Bi_2O_3在可见光照射180 min时,对甲基橙的降解率达到86%。良好的可见光吸收和较低的光生载流子复合是获得优异光催化活性的主要原因。     

Construction of hierarchical nanostructured TiO2/Bi2MoO6 heterojunction for improved visible light photocatalysis

In this study, Bi2MoO6 hollow microspheres were modified by depositing TiO2 nanoparticles through a simple hydrothermal method. The prepared TiO2/Bi2MoO6 photocatalysts were characterized by scanning and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic performance of the heterostructured catalysts was evaluated by degradation of methylene blue (MB) under visible-light irradiation (lambda>420 nm). The photocatalysts based on nanostructured Bi2MoO6 and TiO2 exhibit much higher photocatalytic activity than the single-phase Bi2MoO6 or TiO2 and the mechanical mixture of Bi2MoO6 and TiO2 for degradation of MB under the same conditions. The results reported in this study provide insight into constructing other heterostructured photocatalysts.     

Superparamagnetic ZnFe2O4/ZnS nanocomposites with a highly recyclable for degradation of bisphenol A under visible-light

Journal of Materials Science: Materials in Electronics - Superparamagnetic ZnFe2O4/ZnS core–shell sub-microspheres were fabricated via a two-step forming method for recyclable photocatalytic...     

Enhanced visible light photocatalytic activity of CeO2/alumina nanocomposite: Synthesized via facile mixing-calcination method for dye degradation

In this present study, an effort has been made to novel CeO₂/alumina nanocomposite photocatalyst was fabricated through mixing-calcination method. The XRD, IR, SEM, TEM, EDX and XPS results designated that these synthesized materials are formed effectively. The photocatalytic results for the degradation of dye solution indicate that the most dynamic ratio is CeO₂:Al₂O₃ (2.5:1) under visible light irradiation. The photocatalytic degradation was made under dark and in the presence of light to establish the photocatalytic efficiency of the synthesized photocatalyst. The improved performance of CeO₂/alumina nanocomposite is attributed to the separation efficiency of photo-induced charge carriers and it inhibit charge recombination. The major active species are determined by radical scavengers trapping experiments were revealed that superoxide radical (O₂^?) and hydroxyl radical (OH) are playing a vital role in the degradation of dye solution. The stability of catalyst was confirmed by consecutive runs of CeO₂/alumina nanocomposite.     

Improved visible-light driven photocatalysis by loading Au onto C3N4 nanorods for degradation of RhB and reduction of CO2

In this work, a solution-assembly technique was adopted to compose the g-C₃N₄ (CN) nanorods (CN1, CN2 and CN3) with a desired microstructure. Subsequently, different amounts of Au nanoparticles (NPs) with sizes ~10 nm were loaded on CN2 nanorods by an in-site reduction approach, thereby a series of plasmonic photocatalyst (CN2-A1, CN2-A2 and CN2-A3) were fabricated. The activities were investigated by photodegrading Rhodamine B (RhB) and photoreducing CO₂ into CO with the irradiation of visible light, respectively. And the degradation rates of RhB over CN2-A2 photocatalyst were 97.28% in 80 min, which was 1.45 times higher than that of pure CN2 (66.90%). Moreover, without any sacrificial agents, the reduction yields of CO₂ into CO by CN2-A2 photocatalyst was 3.11 μmol/g in 4 h, that was 2.46 times higher than that of CN2 (1.26 μmol/g). The improved photocatalytic performance was owning to the stronger localized surface plasmon resonance (LSPR) effect, which not only increased the utilization efficiency of visible light, but also sped up the formation and separation of photo-induced carriers. In addition, a potential charge transfer mechanism was tentatively proposed on account of as-obtained test dates.     

Fe_2O_3/ZnFe_2O_4/C复合材料的制备及其电化学性能

本文以葡萄糖作为碳源,采用溶剂热法进行原位碳包覆合成了Fe_2O_3/ZnFe_2O_4/C材料,研究了材料的结构及电化学性能。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、循环伏安扫描(CV)和恒流充放电技术对材料结构及电化学性能进行了表征。结果表明,采用此法合成的Fe_2O_3/ZnFe_2O_4/C复合材料呈现多孔结构,粒径约为250nm,经历40次循环后材料的可逆容量依然能保持在645.7mAh/g,较未包覆碳材料的电极提高了19.0%,其可逆容量和循环稳定性能得到了显著提升。     

纳米Zn/Fe_3O_4水解制备纳米ZnFe_2O_4

用干法室温振动研磨方法制备纳米Zn粉,化学沉淀法制备纳米Fe3O4,纳米Zn和Fe3O4水解制备纳米ZnFe2O4。TEM和XRD检测显示经11h研磨的Zn粉粒度分布在10～20nm之间,纳米Fe3O4的粒度分布在20nm左右,水解产物纳米ZnFe2O4,形貌为方形片状,粒子尺度约为20nm。研究结果表明纳米Zn/Fe3O4摩尔比为1.5∶1,反应温度为300℃是最佳反应条件,可见用振动研磨方法制备的纳米Zn颗粒具有优良的性能,能使化学反应在较低温度下快速完成,且制备方法简单易行,便于批量化生产。     

Electrospun Fe3O4/TiO2 hybrid nanofibers and their in vitro biocompatibility: Prospective matrix for satellite cell adhesion and cultivation

We report the fabrication of novel Fe₃O₄/TiO₂ hybrid nanofibers with the improved cellular response for potential tissue engineering applications. In this study, Fe₃O₄/TiO₂ hybrid nanofibers were prepared by facile sol–gel electrospinning using titanium isopropoxide and iron(III) nitrate nonahydrate as precursors. The obtained electrospun nanofibers were vacuum dried at 80 °C and then calcined at 500 °C. The physicochemical characterization of the synthesized composite nanofibers was carried out by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray diffraction pattern. To examine the in vitro cytotoxicity, satellite cells were treated with as-prepared Fe₃O₄/TiO₂ and the viability of cells was analyzed by Cell Counting Kit-8 assay at regular time intervals. The morphological features of unexposed satellite cells and exposed to Fe₃O₄/TiO₂ composite were examined with a phase contrast microscope whereas the quantification of cell viability was carried out via confocal laser scanning microscopy. The morphology of the cells attached to hybrid matrix was observed by Bio-SEM. Cytotoxicity experiments indicated that the satellite cells could attach to the Fe₃O₄/TiO₂ composite nanofibers after being cultured. We observed that Fe₃O₄–TiO₂ composite nanofibers could support cell adhesion and growth. Results from this study therefore suggest that Fe₃O₄/TiO₂ composite scaffold with small diameters (approximately 200 nm) can mimic the natural extracellular matrix well and provide possibilities for diverse applications in the field of tissue engineering and regenerative medicine.     

The carboxylate magnetic – Zinc based metal-organic framework heterojunction: Fe3O4-COOH@ZIF-8/Ag/Ag3PO4 for plasmon enhanced visible light Z-scheme photocatalysis

In this work, magnetic nanoparticles (MNPs) grafted with carboxylic acid (Fe₃O₄-COOH MNPs) were successfully prepared from incorporation of glutaric anhydride as a functional group on the surface of the ferrite NPs. The MNP was used as a template to induce the growth of ZIF-8 metal–organic framework (MOF) on its surface. The Fe₃O₄-COOH@ZIF-8 core-shell was incorporated with silver phosphate (Ag₃PO₄) and Ag nanoparticles (Ag NPs) to develop a visible light active Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ photocatalyst. The materials were characterized using a range of techniques. The photocatalytic activity was investigated systematically by degrading an organo-phosphorus pesticide, diazinon under visible light irradiation. Among synthesized samples, the Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ heterostructured system exhibited highest photocatalytic activity and improved stability compared to others for the degradation of diazinon under visible light. The superior activity and improved stability of this heterostructured photocatalyst was attributed to the synergistic effects from surface plasmon resonance (SPR) of Ag NPs and sequential energy transfer via Z-scheme mechanism, for effective separation of electron-hole pairs. Radical-trapping experiments demonstrate that holes (h⁺) and O₂⁻ are primary reactive species involved in photocatalytic oxidation process. Moreover, the Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ photocatalyst did not show any obvious loss of photocatalytic activity during five cycle tests, which indicate that the heterostructured photocatalyst was highly stable and can be used repeatedly. Therefore, the work provides new insights into the design and fabrication of metal-organic frameworks (MOFs) for use as a visible light photocatalyst for degrading organic contaminants.