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排序方式： 共有1791条查询结果，搜索用时 31 毫秒
991.
《Ceramics International》2020,46(9):13210-13218
To improve the photocatalytic efficiency of niobium pentoxide (Nb2O5) for the degradation of organic pollutants, a novel nano-fibriform C-modified Nb2O5 (F–C/Nb2O5) photocatalyst was successfully synthesized by niobium oxalate as precursor and nanofibrillated cellulose (NFC) as template and carbon source. Vacuum induced self-assembly method was used to form the nano-fibriform morphology. Compared to ordinary C/Nb2O5 and commercial Nb2O5, F–C/Nb2O5 exhibited a typical three-dimensional nanorod structure with plenty of pores. The specific surface area of F–C/Nb2O5 was 3 times that of C/Nb2O5. The prepared F–C/Nb2O5 exhibited a 3.01 eV bandgap and was able to be activated under visible light while that was unable for commercial Nb2O5 with 3.19 eV bandgap. The F–C/Nb2O5 showed the best photocatalytic efficiency in pH value ≤ 3. After cycling for 5 times, the photocatalytic efficiency of F–C/Nb2O5 was still 2.4 times of the ordinary C/Nb2O5 under visible light. Meanwhile, the self-assembly mechanism and photodegradation mechanism were proposed. This study provides a new strategy to form a special nano-fibriform C-modified niobium pentoxide with extremely high photocatalytic efficiency in aqueous solutions. 相似文献
992.
利用层状结构CsLaTa2O7的亚稳特性,通过水热法在其表面原位合成烧绿石型Na2Ta2O6粒子,构建出CsLaTa2O7/Na2Ta2O6异质结构光催化剂。利用XRD、SEM、TEM、UV⁃Vis光谱和荧光光谱等测试手段,对CsLaTa2O7/Na2Ta2O6样品进行表征。结果表明,CsLaTa2O7/Na2Ta2O6异质结构可以有效地抑制光生电子和空穴的复合,并且在紫外光下光照10 min就能将亚甲基蓝染料完全降解,其紫外光下光催化性能明显高于单一相。 相似文献
993.
《Ceramics International》2020,46(9):13630-13640
Bi3+-containing compounds have been intensively investigated for their potential application as photocatalysts for degrading pollutants and splitting water. In this work, a Ca2Bi2O5/α-Bi2O3 heterojunction photocatalyst was successfully prepared via the facile sol–gel method. The excess of the initial Bi raw material can result in the Ca2Bi2O5/α-Bi2O3 heterojunction of the final products. The as-synthesized nanoparticles were investigated via X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive spectrometry, UV–Vis optical absorption, and X-ray photoelectron spectroscopy. The band energy of the Ca2Bi2O5 substrate semiconductor was 2.49 eV and characterized with a direct transition nature. The photocatalytic effect on the photodegradation of Rhodamine B solutions was evaluated. Ca2Bi2O5/α-Bi2O3 heterojunctions showed improved photocatalytic abilities compared with single Ca2Bi2O5 and α-Bi2O3 under viable light irradiation. The mechanism was discussed in terms of the microstructure, luminescence intensities, and decay curves (lifetimes). The photo-produced electrons and holes can be adequately separated in Ca2Bi2O5/α-Bi2O3 heterojunctions ensuring its photocatalytic activities. The present results can serve as reference for investigating the optical properties of Bi semiconductors. 相似文献
994.
《Ceramics International》2020,46(1):468-475
Rational design of semiconductor membrane photocatalyst with good mechanical flexibility and excellent photocatalytic activity is of significance for environmental remediation. Herein, flexible Ag@ZnO/TiO2 fibrous membranes with hierarchical nanostructures were fabricated through combining a simple electrospinning method and subsequent hydrothermal reaction and photodeposition process. In the ternary nanocomposite, ZnO nanorods were firmly anchored onto TiO2 nanofibers, while Ag nanoparticles were evenly decorated on the surface of both ZnO and TiO2. Benefiting from the improved light absorption, large surface area, and effective charge separation, the resultant Ag@ZnO/TiO2 membranes displayed superior photocatalytic degradation efficiency of 91.6% toward tetracycline hydrochloride within 1 h, and also exhibited prominent antibacterial activity with a 6.5 log inactivation of E. coli after 1 h simulated solar light exposure. Significantly, the membrane photocatalyst still preserved structural integrity and mechanical flexibility after utilization. This study provides an alternative approach for designing and synthesizing flexible TiO2-based membrane photocatalysts toward high-efficiency water purification. 相似文献
995.
《Ceramics International》2020,46(4):4265-4273
Photoactive heterostructures containing CuxS/ZnO/TiO2 have been obtained by spray pyrolysis deposition followed by post-deposition thermal treatment. The ZnO middle layer morphology was tailored by using chemical additives during the deposition. The samples have crystalline structure with average crystallite size around 80 Å for metal oxides and 90 Å for CuxS. The roughness varies from 27.5 nm for CuxS/dZnO/TiO2 to 33.6 nm for CuxS/pZnO/TiO2 samples. The wettability properties were tested based on the contact angle measurements. The highest surface energy value (106.4 mN/m) corresponding to CuxS/pZnO/TiO2 with 30 min UV irradiation, with a predominant polar component of 85.3 mN/m. The photocatalytic efficiency under UV–Vis light irradiation was evaluated using methylene blue and phenol as pollutants. The highest photocatalytic values (93.4% for methylene blue and 72.3% for phenol) were obtained for CuxS/pZnO/TiO2 heterostructure with successive 30 min UV irradiation at 2 h intervals. The mineralization efficiency was tested using total organic carbon analysis and the results are slightly lower compared with photocatalytic efficiency. 相似文献
996.
《Advanced Powder Technology》2020,31(1):1-10
The ternary ZnO-ZnFe2O4/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/ZnFe2O4 nanoparticles with size of 25–30 nm were adequately anchored on the palygorskite fibers surface. Compared with ZnO, ZnFe2O4, ZnO/ZnFe2O4 and ZnO/palygorskite, the ZnO-ZnFe2O4/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
997.
《Advanced Powder Technology》2020,31(4):1708-1719
The conventional synthesis of ultrathin BiOBr nanoplates (U-BBN) needs closed-vessel high-temperature processes. Herein, we prepare well-crystalline U-BBN in an open-vessel at room-temperature through the support of poly (sodium 4-styrenesulfonate) (PSS). Results uncover that PSS creates an intermediate PSS-Bi(OCH2CH2OH) composite which constricts the spontaneous growth rate of BiOBr nanoplates along 〈0 0 1〉 direction, and thus generates the U-BBN with 6–7 nm ultrathin thicknesses and 70–80 nm of planar size. Interestingly, instead of using centrifugation, U-BBN product was collected due to self-precipitation, and by scaling-up the reaction vessel, about 5.26 g of U-BBN was obtained with well-controlled size and thicknesses. As compared to thick BiOBr nanoplates (BBN), U-BBN presents high specific surface area, narrower energy bandgap, plentiful oxygen vacancies, significantly improved ability to separate photoinduced electron-holes and good tendency to suppress the probability of charge recombination. Consequently, under the visible light irradiation, the catalytic performance of U-BBN to degrade the antibiotic ciprofloxacin substantially exceeds the BBN and state-of-the-art photocatalysts. Also, U-BBN demonstrate noteworthy potential to photodegrade rhodamine B and to reduce Cr(VI) ions from aqueous solution. This work provides the first scalable, environmental-friendly and economical alternative to produce highly active ultrathin BiOBr photocatalyst, and might have potential to be broadened for other functional materials. 相似文献
998.
《Advanced Powder Technology》2020,31(2):533-547
Dimethyl phthalate esters (DMPEs) have been identified as endocrine disrupting plastisizers and emerging contaminants which can be released readily upon exposure to the environment. In this study, MWCNTs/TiO2 nanocomposites, which possess the potential application for the photocatalytic degradation of DMPEs under UV irradiation, were prepared via simple one-pot sol-gel reaction using titanium isopropoxide (TTIP) as titania precursor and multiwalled carbon nanotubes (MWCNTs). The MWCNTs/TiO2 nanocomposites was calcined in air for 2 h at the temperatures ranging from 350 to 750 °C. As a result, the MWCNTs/TiO2 nanocomposites synthesized at calcination temperature of 450 °C demonstrated the highest photodegradation efficiency of 97% after 180 min UV irradiation and its degraded products were evaluated using the ultra high performance liquid chromatography (UHPLC) coupled with a high resolution (HR) Orbitrap mass spectrometry (MS). A primary degradation mechanism was proposed and it was noteworthy that some new intermediates were discovered and reported. This work has developed a simple method for qualitative determination of DMPEs based on HPLC with UV detection. 相似文献
999.
《中国稀土学报(英文版)》2020,38(1):29-38
In the present work,we have synthesized samarium doped zinc oxide nanostructures(Zn_(1-x)Sm_xO;x=0.00,0.02,0.04 and 0.06) via chemical precipitation method and studied their structural,morphological,optical and photocatalytic properties.X-ray diffraction(XRD) patterns,PL and Raman spectra results indicate that the undoped and Sm-doped ZnO nanostructures are crystallized in a hexagonal wurtzite structure.FESEM images show that the morphology of the sample changes from cubical to hexagonal nanostructures with increase in Sm~(3+)doping concentration.The EDX spectra confirm the incorporation of Sm~(3+)ion in ZnO.The influence of Sm~(3+)doping on the structure,morphology,absorption,emission and photocatalytic activity of ZnO nanostructures were investigated systematically.The addition of Sm~(3+)ion leads to a red shift in the optical energy band gap from 3.19 to 2.67 eV and hence,increases the visible light absorption ability.The presence of E_2(H) and E_1(LO) modes in microRaman spectra confirms the crystallinity and defects in the samples.The detailed photocatalytic experiments reveal that Sm-doped ZnO nanostructures show the maximum photodegradation efficiency for Methylene blue(MB) dye for x=0.04,i,e.,94.94%,under visible light irradiation.The photocatalytic efficiency improves by 6.98 times when ZnO is doped with rare earth metal ion(Sm~(3+)) and is a potential candidate for practical applications.The investigation demonstrates that as-synthesized nano-sized photocatalysts act as an efficient photocatalyst for the degradation of MB dye. 相似文献
1000.
《Beton- und Stahlbetonbau》2017,112(1):47-53
Photocatalitically Active Concrete: How Innovative Construction Materials Can Contribute to the Degradation of Dangerous Air Pollutants The handling of environmental pollution caused by air pollutants like NOX, SO3 and volatile organic compounds (VOCs) is still a major challenge, especially in urban areas. One possibility to degrade these substances is by their oxidation on the surface of an illuminated photocatalyst, like the well known white pigment titanium dioxide (TiO2). Under illumination, oxidizing species are formed on the TiO2 surface, which are then able to decompose organic and inorganic species. By direct adding of or supplementary coating with the photocatalyst innovative building materials like concrete, plaster, floor plates and roof tiles are accessible, which not only fulfill their main task but also improve the air quality of the environment. 相似文献