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1.
A one-pot, solvent-thermal process was used to create the ultrafine ZnFe 2O 4 nanoparticles photocatalyst. During the solvent-thermal process, the in situ self-forming NaCl not only served as a “cage” to confine the ion diffusion, but also acted as a microreactor for nanocrystallite growth. An average particle size of ~10 nm and a high-specific surface area of ~112.9 m 2/g were observed for the ultrafine ZnFe 2O 4 nanoparticles Owing to the synergistic effect of ultrafine particle size, the full utilization of the visible light region and high conduction band (CB) position, ultrafine ZnFe 2O 4 photocatalyst displayed an efficient photocatalytic CO 2 reduction under visible light illumination. Besides, the ultrafine ZnFe 2O 4 photocatalyst showed high production selectivity for CH 3CHO and C 2H 5OH generation in aqueous CO 2/NaHCO 3 solution. This work may provide a new idea for the synthesis of new high-efficiency photocatalysts. 相似文献
2.
Heterostructured Fe 3O 4/Bi 2O 2CO 3 photocatalyst was synthesized by a two-step method. First, Fe 3O 4 nanoparticles with the size of ca. 10 nm were synthesized by chemical method at room temperature and then heterostructured Fe 3O 4/Bi 2O 2CO 3 photocatalyst was synthesized by hydrothermal method at 180 °C for 24 h with the addition of 10 wt% Fe 3O 4 nanoparticles into the precursor suspension of Bi 2O 2CO 3. The pH value of synthesis suspension was adjusted to 4 and 6 with the addition of 2 M NaOH aqueous solution. By controlling the pH of synthesis suspension at 4 and 6, sphere- and flower-like Fe 3O 4/Bi 2O 2CO 3 photocatalysts were obtained, respectively. Both photocatalysts demonstrate superparamagnetic behavior at room temperature. The UV–vis diffuse reflectance spectra of the photocatalysts confirm that all the heterostructured photocatalysts are responsive to visible light. The photocatalytic activity of the heterostructured photocatalysts was evaluated for the degradation of methylene blue (MB) and methyl orange (MO) in aqueous solution over the photocatalysts under visible light irradiation. The heterostructured photocatalysts prepared in this study exhibit highly efficient visible-light-driven photocatalytic activity for the degradation of MB and MO, and they can be easily recovered by applying an external magnetic field. 相似文献
3.
Novel cobalt oxide doped ZnFe 2O 4-Fe 2O 3-ZnO mixed oxides with the Zn/Fe molar ratio of 1/2 were synthesized with a citric acid complex method. The effects of cobalt oxide and calcination temperature on phase composition and photocatalytic activity of the mixed oxides were investigated. X-ray diffraction (XRD) analysis revealed that there were mainly ZnFe 2O 4, α-Fe 2O 3, amorphous ZnO and Fe 2O 3 in the 6 mol% cobalt oxide doped products calcined at 500 °C. 5-10 mol% cobalt oxide doping could significantly enhance the formation of ZnFe 2O 4 and altered the phase composition of the mixed oxides. Experimental results showed that cobalt oxide doping could remarkably improve the photocatalytic activity of the mixed oxides for phenol degradation. The 6 mol% cobalt oxide doped mixed oxides calcined at 500 °C exhibited better photocatalytic activity as compared with other samples. 相似文献
4.
Polyaniline-modified Fe 3O 4/SiO 2/TiO 2 composite microspheres have been successfully synthesized by sol–gel reactions on Fe 3O 4 microspheres followed by the chemical oxidative polymerization of aniline. The synthesized multilayer-structured composites were characterized by TEM, XRD, TGA, UV–vis diffuse reflectance spectra and magnetometer. The photocatalytic activity was evaluated by the photodegradation of methylene blue under visible light. The effect of polyaniline (PANI) amounts on the photocatalytic activity was investigated. The photocatalytic activity results show that the Fe 3O 4/SiO 2/TiO 2 composites with about 2.4 wt.%–4.1 wt.% PANI could show higher photocatalytic efficiency than that of Fe 3O 4/SiO 2/TiO 2. Furthermore, the PANI-Fe 3O 4/SiO 2/TiO 2 photocatalyst could be easily recovered using a magnet. 相似文献
5.
In situ polymerization of aniline is carried out in the presence of zinc ferrite to synthesize polyaniline/ZnFe 2O 4 composites (PANI/ZnFe 2O 4) by chemical oxidation method. The composite has been synthesized with various compositions (10, 20, 30, 40 and 50 wt.%) of zinc ferrite in PANI. From the infrared spectroscopy (FTIR) studies on polyaniline/ZnFe 2O 4 composites, the peak at 1140 cm ?1 is considered to be measure of the degree of electron delocalization. The surface morphology of these composites is studied with scanning electron micrograph (SEM). The ac conductivity and dielectric properties are studied in the frequency range from 10 2 to 10 6 Hz. The results obtained for these composites are of scientific and technological interest. 相似文献
6.
Porous zinc ferrite (ZnFe 2O 4) nanorods have been synthesized by the thermal decomposition of ZnFe 2(C 2O 4) 3 nanorods precursor, which was prepared by template-, surfactant-free solvothermal method. The morphology and structure of the obtained ZnFe 2(C 2O 4) 3 nanorods precursor and porous ZnFe 2O 4 nanorods were characterized by X-ray powder diffraction, transmission electron microscopy, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicated that the as-synthesized ZnFe 2O 4 retained the precursor morphology of 1D nanorods with diameters of 100–200 nm and lengths of several micrometers and plenty of nanoparticles were interconnected to each other to form porous nanorods. The as-prepared ZnFe 2O 4 nanorods as a kind of subsequently light-driven photocatalyst exhibited good photocatalytic decomposition activity for methylene blue (MB). 相似文献
7.
In this work, magnetic nanoparticles (MNPs) grafted with carboxylic acid (Fe 3O 4-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 Fe 3O 4-COOH@ZIF-8 core-shell was incorporated with silver phosphate (Ag 3PO 4) and Ag nanoparticles (Ag NPs) to develop a visible light active Fe 3O 4-COOH@ZIF-8/Ag/Ag 3PO 4 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 Fe 3O 4-COOH@ZIF-8/Ag/Ag 3PO 4 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 O 2− are primary reactive species involved in photocatalytic oxidation process. Moreover, the Fe 3O 4-COOH@ZIF-8/Ag/Ag 3PO 4 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. 相似文献
8.
Spinel ferrite ZnFe2O4 nanostructures have been prepared as sunlight responsive photocatalysts via facile co-precipitation method. The structural, morphological, and optical responses were diligently characterized using XRD, Raman spectroscopy, FESEM, and UV–Vis absorption spectroscopy, respectively. FESEM studies revealed nanoparticles and porous-like nanoparticle aggregates, found to be of cubic spinel ZnFe2O4 from XRD and Raman studies. Crystallite size varied from 5 to 13.6 nm, whereas band gap changed from 1.89 to 1.95 eV with CTAB concentration variation. ZnFe2O4 nanostructures were employed for sunlight-assisted photodegradation of organic pollutants such as MB, MG, and MO dyes in water. The synthesized ZnFe2O4 nanoparticle aggregates with porous-like morphology with crystallite size of 9.2 nm showed superior photocatalytic response and decomposed 80.4% of MB dye in only 40 min. The superiority of the porous-like ZnFe2O4 nanoparticle aggregates was mainly ascribed to its optimal crystallite size, narrower band gap, and improved sunlight utilization efficiency. A plausible mechanism of photocatalytic oxidation of dye supported by scavenger studies has also been proposed. The synthesized ZnFe2O4 nanostructures have easy magnetic recycling property along with excellent photocatalytic capability and hold potential for the treatment of contaminated water. 相似文献
9.
In this study, pure ZnO microbullets, ZnO–ZnFe 2O 4 composite, and ZnO–Fe 2O 3–ZnFe 2O 4 composite with micron structured balloons, rods, and particles were prepared by a simple solvent thermal process using methanol
or ethanol as solvents. The influence of solvents on the composition and morphology of the products was studied, and their
gas-sensing properties were also investigated. The morphology of ZnO microbullets synthesized in ethanol is similar to but
more uniform than that of ZnO microbullets synthesized in methanol. The Fe-doped ZnO synthesized in ethanol contains many
micron particles homogeneously dispersing on the surface of the microbullets, which is composed of hexagonal wurtzite ZnO
and franklinite ZnFe 2O 4, while Fe-doped ZnO prepared in methanol consists of micron structured balloons, rods, and particles, which is composed of
hexagonal wurtzite ZnO, hematite Fe 2O 3, and franklinite ZnFe 2O 4. Compared with pure ZnO and ZnO–ZnFe 2O 4 composite, the ZnO–Fe 2O 3–ZnFe 2O 4 composite presented high response, rapid response/recovery characteristics, good selectivity, and excellent stability to
acetone at relatively low operating temperature of 190 °C. This sensor could detect acetone in wide range of 1–1000 ppm, which
was expected to be a promising gas sensor for detecting acetone. 相似文献
10.
Novel Ag 2O-BaFe 12O 19/C 3N 4 composites were prepared via a grind, solvothermal and deposition–precipitation methods. The physicochemical properties of the samples were tested by FT-IR, XRD, SEM, TEM, XPS, DRS, ESR, VSM, photocurrent test, and electrochemical impedance spectra test, respectively. The characterization manifested that Ag 2O was firmly anchored to the BaFe 12O 19/C 3N 4 to form heterogeneous hybrid. Most importantly, the formation of Ag 2O-BaFe 12O 19/C 3N 4 effectively promoted the charge transfer, eventually enhancing the photocatalytic performance. Meanwhile, the activity of the photocatalysts were assessed by photocatalytic removal of tetracycline (TC) under visible light irradiation. The results showed that Ag 2O-BaFe 12O 19/C 3N 4 photocatalyst has better photocatalytic activities than the pure component. The degradation rate reaches 80 % after 15 min, which is nearly 1.56 times higher than that of pure g-C 3N 4. The effects of Ag 2O content, photocatalyst dosage, pH value on TC degradation performances were studied in detail, respectively. The experimental results verified that pH value exhibited significant effects on TC degradation. The TC degradation rate was highest only when the initial solution pH = 7. This indicates that the photocatalyst also has high activity in neutral environment, and no additional pH adjustment is required. The results of plant growth test (mung bean seeds) showed that the degradation intermediates showed lower toxicity. Based on experiments and characterization, the possible carrier migration and photocatalytic degradation mechanism were proposed. 相似文献
11.
A composite of Fe 2O 3 capped by conductive polyaniline (PANI) was synthesized by a facile two-step method through combining homogeneous Fe 2O 3 suspension prepared by a hydrothermal method and in-situ polymerization of aniline. As anode material for lithium ion batteries, the Fe 2O 3/PANI composite manifests very large discharge capacities of 1635 mAh g −1, 1480 mAh g −1 at large currents of 1.0 and 2.0 A g −1 (1C and 2C), respectively, as well as good cycling performance and rate capacity. The enhancement of electrochemical performance is attributed to the improved electrical conductivity and effective ion transportation of the composite electrode, in that, PANI keeps the Fe 2O 3 nanorods uniformly connected and offers conductive contact between the electrolyte and the active electrode materials. 相似文献
12.
Two serious problems for semiconductor photocatalysts are their poor photocatalytic activity and low stability. In this work, Ag 2CO 3 nanoparticles incorporated in mordenite zeolite (MOR) by a facile precipitation method. Silver bromide (AgBr) with different weight percentage (20%, 40% and 50%) was coupled into Ag 2CO 3-MOR composite and producing a series of novel AgBr/Ag 2CO 3-MOR nanocomposites. The effects of AgBr on the Ag 2CO 3–MOR catalyst for the photocatalytic degradation of methyl blue (MB) under visible light irradiation have been investigated. The structure, composition and optical properties of nanocomposites were investigated by UV–Visible diffuse reflectance spectroscopy (UV–Vis DRS), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM). The prepared AgBr/Ag 2CO 3-MOR photocatalyst with the optimal content of AgBr (50 wt%) indicated higher photocatalytic activity than that of the Ag 2CO 3-MOR and Ag 2CO 3 for degradation of methylene blue (MB) under visible light irradiation. For studying of stability of nanocomposites, Fe +3 ions, as a cheap and available cocatalyst, was inserted into mordenite matrix (Fe 3+/MOR) by impregnation method. The hybrid material (AgBr/Ag 2CO 3) was synthesized in the Fe 3+/MOR matrix by precipitation method. The cycle experiments on the AgBr/Ag 2CO 3-Fe/MOR nanocomposite indicated that cocatalyst, not only to improve photocatalytic activity, but also enhance photoinduced stability of photosensitive silver compounds in all cycles with respect to MOR. On the basis of the experimental results, a possible mechanism for the enhanced photocatalytic activity and photoinduced stability of silver compounds by Fe 3+ cocatalyst was proposed. The mordenite support played an important role in decreases of recombination of photogenerated electrons-holes and increases of MB absorption. The Fe cocatalyst reduced photocorrosion of silver compounds. 相似文献
13.
A highly efficient binary CdIn2S4/g-C3N4 heterojunction photocatalyst was synthesized by a simple wet impregnation method. Photocatalytic system based on the synergistic action of binary CdIn2S4/g-C3N4 heterojunction and H2O2 was proposed to improve the degradation effect of dyes. The photocatalytic activity was evaluated by the degradation of methyl orange(MO) under visible light irradiation. The results demonstrated that contrasted to pure g-C3N4, the synthesized heterojunction can significantly improve the photocatalytic activity. After 120 min of irradiation by visible light, the photocatalytic efficiency of MO degradation of 7CIS/CN was 3.13 times higher than that of g-C3N4. When 60 mM H2O2 was added on this basis, the photocatalytic efficiency increased from 93.81 to 99.40%. The improvement of photocatalytic activity is attributed to the formation of binary CdIn2S4/g-C3N4 heterojunction to promote the transfer of photogenerated electron-hole pairs, and an appropriate amount of H2O2 as an electron trap further reduced the recombination rate of photogenerated electron-hole pairs. Active species capture experiments showed that ·O2? are the main active substances. Subsequently, the mechanism of photocatalytic degradation was proposed. This work provided a new efficient strategy for the degradation of industrial dye wastewater. 相似文献
14.
The ternary ZnO-ZnFe 2O 4/palygorskite composite photocatalysts were fabricated via a solvothermal method followed by thermal treatment. The structure, morphology and photoelectric performances of samples were characterized, and the results indicated that ZnO/ZnFe 2O 4 nanoparticles with size of 25–30 nm were adequately anchored on the palygorskite fibers surface. Compared with ZnO, ZnFe 2O 4, ZnO/ZnFe 2O 4 and ZnO/palygorskite, the ZnO-ZnFe 2O 4/palygorskite composite photocatalysts exhibited significantly improved photocatalytic activity in degradation of methylene blue (MB). Especially, the optimal photocatalyst (ZF1.5) displayed the highest photocatalytic activity, achieving 99.68% and 99.48% degradation efficiency after 90 min of UV–vis (350 ≤ λ ≤ 780 nm) and 100 min of visible-light (λ ≥ 420 nm) irradiation, respectively. The photocatalysis degradation process matched well with the Langmuir-Hinshelwood kinetics. The obtained improvement of photocatalytic activity was ascribed to the synergetic effect of superior visible-light utilization; effective charge carrier separation and palygorskite support effect (optimize nanoparticles dispersibility, developed mesoporous structure, enlarge specific surface area and increase adsorption capacity). 相似文献
15.
A novel ternary heterojunction composite photocatalyst g-C3N4/TiO2/NiWO4 was fabricated using a simple hydrothermal method. The synthesized samples were characterized using X-ray diffraction (XRD), scanning electronic microscopy (SEM), energy-dispersive spectrum (EDS), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis) absorption spectra, photoluminescence (PL) spectra, transient photocurrent responses, and electrochemical impedance spectroscopies (EIS). The results indicated that the composite of g-C3N4/TiO2/NiWO4 had been successfully synthesized. By constructing a ternary heterojunction, the electron migration rate and light absorption of the material are further improved; the photogenerated electron–hole recombination is inhibited. The ternary composite photocatalyst shows the highest photocatalytic activity for the degradation of rhodamine B (RhB) than that of g-C3N4, TiO2, NiWO4, and g-C3N4/TiO2 photocatalyst. The degradation efficiency of RhB using g-C3N4/TiO2/NiWO4 can reach 99% after visible-light irradiation for 40 min. Finally, the migration mechanism of charge carriers in the ternary system has been schematically illustrated by the active species capture experiment. Our research can pave the way for the fabrication of ternary heterojunction composite photocatalyst with high photocatalytic activity for the environmental contaminants treatment. 相似文献
16.
Both photocatalysis and Fenton-like catalysis present promising and potential technologies for water purification. However, single photocatalysis or Fenton-like catalysis cannot meet the practical demand for complicated pollutes treatment in water. Herein, we report an environmentally benign Ag 3PO 4/CuO catalysts that combine the two catalysis. The synthesized Ag 3PO 4 acts as an efficient photocatalyst, and Fenton-like CuO catalysis decomposes organic pollutes in the presence of H 2O 2. A series of Ag 3PO 4/CuO composites were obtained by regulating the molar ratio of Ag 3PO 4 to CuO via hydrothermal and ion exchange reactions. The optimized composite shows a significant improvement in catalytic activity over pure Ag 3PO 4 under visible light or CuO with H 2O 2, owing to the synergistic effect of photocatalysis and Fenton-like catalysis. It is noticeable that the Ag 3PO 4/CuO composites retain efficient performance even after five cycling runs. The catalytic mechanism involves matched band structures, Z-scheme photocatalytic mechanism, and the generation of a large amount of hydroxyl radicals. 相似文献
17.
In this work, Z-scheme Ag 2S/Bi 2O 3 composites were fabricated through the precipitation of Ag 2S nanoplates on the surface of Bi 2O 3 microrods. Consequently, Au nanoparticles were selectively deposited on the Ag 2S nanoplates surface to obtain.Au-Ag 2S/Bi 2O 3 composites using near-infrared light photodeposition method. The characterization results indicate that the Ag 2S nanoplates were uniformly anchored on Bi 2O 3 surface, and Au nanoparticles were highly dispersed on the surface of Ag 2S nanoplate instead of Bi 2O 3. Acid orange 7 (AO7), Rhodamine B (RhB) and Cr(VI) were chosen as model reactant for the evaluation of photocatalytic degradation and reduction activity of the products under simulated sunlight irradiation. After the decoration of Ag 2S nanoplates, the photocatalytic activity of Ag 2S/Bi 2O 3 is much higher than that of bare Bi 2O 3, and the optimal catalytic efficiency is achieved by 12 %Ag 2S/Bi 2O 3 sample. More importantly, the photocatalytic activity of 12 %Ag 2S/Bi 2O 3 sample can be further enhanced by the selective decoration Au nanoparticles on the Ag 2S nanoplates. Among the ternary composites, 2Au-12 %Ag 2S/Bi 2O 3 sample with the Au content of 2% exhibits highest catalytic efficiency for 60 min (AO7: 96%; RhB: 56%; Cr(VI): 65%). The possible mechanism for the improvement of the photocatalytic activity of Bi 2O 3 by Ag 2S and Au decoration was proposed. 相似文献
18.
Nanostructured ferrite spinels AFe 2O 4 (A = Co, Ni, Zn) were successfully synthesized via a co-precipitation method using oxalate salt as a precursor in an anionic surfactant system in combination with a simple calcination process. High crystallinity samples of nanoparticle spinels in a grain size range of 15–100 nm were obtained by varying the calcination temperature (300–700 °C) and time (1–5 h). Their pore sizes were controlled in a range of 3 nm up to a hundred nm by tailoring the calcination conditions. Raising the calcination temperature was found to decrease the Brunauer–Emmett–Teller (BET) surface area, and broaden the pore structure due to enhanced crystal growth and agglomeration of interparticles of spinels. Transmission electron microscopy (TEM) images of ferrite spinels calcined at 300 °C showed mesoporous structures with narrow pore size distribution, and the maximum BET surface area of CoFe 2O 4, NiFe 2O 4 and ZnFe 2O 4 were found at 201 (Co), 315 (Ni), and 273 (Zn) m 2 g −1, respectively. The magnetic hysteresis loops of the ferrite spinels at room temperature demonstrated ferromagnetism in CoFe 2O 4, superparamagnetism–ferromagnetism in NiFe 2O 4, and paramagnetism in ZnFe 2O 4. The highest saturation magnetization ( Ms), remanent magnetization ( Mr), and coercivity ( Hc) were obtained from high crystallinity spinels calcined at 700 °C. Nanostructured AFe 2O 4 with high surface area and mesoporosity promises potentials as novel magnetic catalysts. 相似文献
19.
Construction of heterojunction with reusability is one of the effective ways to avoid secondary pollution and strengthen photocatalysis. Herein, a magnetically recyclable Z-scheme Bi 4O 5I 2/NiFe 2O 4 heterojunction photocatalyst was successfully fabricated by a two-step hydrothermal method. Through adjusting the theoretical molar proportion of NiFe 2O 4 to Bi 4O 5I 2, it was verified that the optimal composite could decompose 98.5% Rhodamine B (RhB, 10 mg/L) within 60 min under simulative sunlight and 98.1% RhB within 80 min under visible light. According to the characterizations, the superior performance was mainly associated with the small band gap energy (2.44 eV) and efficient separation of photo-generated electrons and holes caused by the formation of heterojunction. Meanwhile, the enlarged specific area (27.6 m 2/g) provided many adsorptive sites and active sites to improve the reaction further. Moreover, the trapping experiment indicated that the photodegradation involved O 2–, OH and h +. After confirming the reliable activity, reusability and stability of the photocatalyst, an inferred mechanism was shown. In summary, the design of this magnetically recyclable Z-scheme Bi 4O 5I 2/NiFe 2O 4 heterojunction photocatalyst can become a new choice to purify wastewater. 相似文献
20.
The fabrication and photocatalytic application of zinc ferrite nanocrystals were reported. Quasi-cube ZnFe 2O 4 nanocrystals with typical small sizes of 5-15 nm were successfully synthesized by a facile hydrothermal approach. ZnFe 2O 4/P25 nanocomposite was prepared by physically grinding the ZnFe 2O 4 nanocrystals with TiO 2 (commercial Degussa P25) at ambient temperature, and it exhibited excellent photocatalytic activity for the mineralization of Rhodamine B. UV-vis measurement and photocatalytic test results showed that ZnFe 2O 4 nanocrystals exhibited effective band-gap coupling to P25 nanopowders by simply physical grinding without any surface modification or high-energy balling, which is usually adopted in conventional mixture process. This phenomenon can be attributed to the high surface activities of the as-obtained tiny ZnFe 2O 4 nanocrystals and commercial P25 nanoparticles. It may imply that the mixing process of composite materials would be simplified by further lowering the grain sizes of their component particles. 相似文献
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