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1.
Novel ZnO/N‐doped helical carbon nanotubes (ZnO/N‐HCNTs) composites were successfully synthesized via a facile chemical precipitation approach at room temperature. The sample was well characterized by X‐ray diffraction (XRD), energy dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM) and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activity was evaluated in the degradation of methylene blue (MB) aqueous solution under UV light irradiation. It is found that ZnO nanoparticles were highly and uniformly anchored on the surface and inner tubes of the N‐HCNTs with size of about 5 nm, and significantly enhanced the photocatalytic activity compared to pure ZnO. The enhanced photocatalytic activity of ZnO/N‐HCNTs composites can be ascribed to the integrative synergistic effect of effective interfacial hybridization between N‐HCNTs and ZnO nanoparticles and the prolonged lifetime of photogenerated electron–hole pairs. Moreover, the ZnO/N‐HCNTs could be easily recycled without any obvious decrease in photocatalytic activity and could be promote their application in the area of environmental remediation.  相似文献   

2.
Dysprosium (Dy)‐doping SrMoO4 (with different molar ratio of Dy/Sr = 0/100, 10/100, 15/100 and 20/100) have been synthesized by high temperature thermal decomposition of metal–organic salt in organic solvent with a high boiling point. Their structures, morphology, and optical properties were characterized by X‐ray diffraction (XRD), high‐resolution tuning electron microscopy ((HR)TEM), X‐ray photo‐electron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). Using this method, the pure phase, nano‐size, and low band gap of SrMoO4 sample are obtained. The results shows that the size of as‐synthesized SrMoO4 nanoparticles was about 200 nm. The band gap of Dy‐doped SrMoO4 ranges from 3.76–3.90 eV, and decreases with increasing Dy concentration. The photocatalytic performance of as‐syntheszied products were determined from the degradation of methylene blue (MB) by UV–vis light irradiation. The 15 mol%Dy‐doped SrMoO4 sample shows the best performance for photocatalytic degradation of methyl blue of nearly 100% in 120 min under visible irradiation, which is higher than most of those reported before. The present work is meaningful for revealing the underlying mechanism in photocatalyst and improving the photocatalytic performance.  相似文献   

3.
High aspect ratio cobalt doped ZnO nanowires showing strong photocatalytic activity and moderate ferromagnetic behaviour were successfully synthesized using a solvothermal method and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), vibrating sample magnetometry (VSM) and UV–visible absorption spectroscopy. The photocatalytic activities evaluated for visible light driven degradation of an aqueous methylene orange (MO) solution were higher than for Co doped ZnO nanoparticles at the same doping level and synthesized by the same synthesis route. The rate constant for MO visible light photocatalytic degradation was 1.9·10−3 min−1 in case of nanoparticles and 4.2·10−3 min−1 in case of nanowires. We observe strongly enhanced visible light photocatalytic activity for moderate Co doping levels, with an optimum at a composition of Zn0.95Co0.05O. The enhanced photocatalytic activities of Co doped ZnO nanowires were attributed to the combined effects of enhanced visible light absorption at the Co sites in ZnO nanowires, and improved separation efficiency of photogenerated charge carriers at optimal Co doping.  相似文献   

4.
Ag-doped ZnO nanoparticles (Zn1?xAgxO; where x = 0.00–0.05) were synthesized by chemical precipitation method. The synthesized products were characterized by X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope (TEM) and UV–Vis spectrometer. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology and the measurements show that the size of crystallites is in the range of 10–40 nm. Optical measurements indicated a red shift in the absorption band edge after Ag doping. The band gap values of as prepared undoped and doped with silver samples were found to decrease with increase in temperature from 300 to 800 °C. Photocatalytic activities of ZnO and Ag doped ZnO were evaluated by irradiating the sample solution to ultraviolet light by taking methylene blue as organic dye. The experiment demonstrated that the photo-degradation efficiency of 1 mol% Ag-doped ZnO was significantly higher than that of undoped and 2–5 mol% Ag doped ZnO under ultraviolet light irradiation.  相似文献   

5.
In the present work, Zinc Oxide (ZnO) nanoparticles (NPs) were synthesized by the chemical co-precipitation method using Zinc Chloride as the initial chemical, while Nickel and Cobalt chloride as dopants. Phase identification of metal (Ni, Co) doped Zinc Oxide nanoparticles (NPs) was observed using x-ray diffraction (XRD). The small lattice distortion or phase changes appeared due to shifting of diffraction angles peaks towards larger angle in ZnO are corresponded to metal (Ni, Co) dopant. The average crystallite size appears to decrement in NP size from 7.67 nm to 6.52 nm and 5.35 nm to 5.17 nm with increasing 5 % to 80 % of metal (Ni, Co) dopant respectively. The optical characteristics, including the absorption spectra of the prepared sample were observed through UV–Vis spectroscopy, Meanwhile SEM confirmed the observation of composition change in specimen with metal (Ni, Co) dopant concentration. The bandgap value was also found decrement 5.23 eV to 5.05 eV with increment of metal (Ni, Co) dopant concentration. The functional groups were measured by Fourier transformation infrared spectroscopy (FTIR). FTIR peaks found the metal (Ni, Co) doped ZnO with the vibration mode of (Zn2+ –O2?) ions due to the increment of dopant concentrations. Furthermore, electrical results show the ohmic behavior of prepared samples. These findings indicate the possibility of tuning optical, structural and electrical properties of metal (Ni, Co) doped ZnO with various dopant concentrations of Nickel and will have great potential to find application in optoelectronic devices.  相似文献   

6.
A systematic experimental and theoretical study of the origin of the enhanced photocatalytic performance of Mg‐doped ZnO nanoparticles (NPs) and Mg‐doped ZnO/reduced graphene oxide (rGO) nanocomposites has been performed. In addition to Mg, Cd was chosen as a doping material for the bandgap engineering of ZnO NPs, and its effects were compared with that of Mg in the photocatalytic performance of ZnO nanostructures. The experimental results revealed that Mg, as a doping material, recognizably ameliorates the photocatalytic performance of ZnO NPs and ZnO/graphene nanocomposites. Transmission electron microscopy (TEM) images showed that the Mg‐doped and Cd‐doped ZnO NPs had the same size. The optical properties of the samples indicated that Cd narrowed the bandgap, whereas Mg widened the bandgap of the ZnO NPs and the oxygen vacancy concentration was similar for both samples. Based on the experimental results, the narrowing of the bandgap, the particle size, and the oxygen vacancy did not enhance the photocatalytic performance. However, Brunauer–Emmett–Teller (BET) and Barret–Joyner–Halenda (BJH) models showed that Mg caused increased textural properties of the samples, whereas rGO played an opposite role. A theoretical study, conducted by using DFT methods, showed that the improvement in the photocatalytic performance of Mg‐doped ZnO NPs was due to a higher electron transfer from the Mg‐doped ZnO NPs to the dye molecules compared with pristine ZnO and Cd‐doped ZnO NPs. Moreover, according to the experimental results, along with Mg, graphene also played an important role in the photocatalytic performance of ZnO.  相似文献   

7.
用微波辅助多元醇法对预先制备的ZnO微米球进行修饰,合成了载银氧化锌微米球(ZnO/Ag). 利用X射线衍射仪、场发射扫描电子显微镜、透射电子显微镜、X射线光电子能谱仪、紫外-可见双光束分光光度计和光致发光光谱仪等对样品的结构、形貌和光学性能进行了表征. 在紫外光照射下,通过亚甲基蓝的降解反应研究了样品的光催化活性. 结果表明,所制备的ZnO/Ag微米球是由面心立方的Ag纳米颗粒附着在纤锌矿结构的ZnO球表面形成;与ZnO相比,ZnO/Ag的紫外-可见光吸收光谱发生明显红移,在紫外和可见光范围均有较强的吸收;随着Ag含量的增加,ZnO/Ag荧光光谱强度先减弱后增强;与ZnO相比,ZnO/Ag的光催化活性明显提高,AgNO3 浓度为0.05 mol/L时制得的ZnO/Ag光催化活性最高.  相似文献   

8.
Nitrogen doped zinc oxide (ZnO) nanoparticles have been synthesized using a colloidal route and low temperature nitridation process. Based on these results, 200 nm thick transparent ZnO thin films have been prepared by dip-coating on SiO2 substrate from a ZnO colloidal solution. Zinc peroxide (ZnO2) thin film was then obtained after the chemical conversion of a ZnO colloidal thin film by H2O2 solution. Finally, a nitrogen doped ZnO nanocrystalline thin film (ZnO:N) was obtained by ammonolysis at 250 °C. All the films have been characterized by scanning electron microscopy, X-ray diffraction, X-Ray photoelectron spectroscopy and UV–Visible transmittance spectroscopy.  相似文献   

9.
In this study, the synthesis of ZnO/SiO2 nanocomposites using bamboo leaf ash (BLA) and tested their photocatalytic activity for rhodamine B decolorization have been conducted. The nanocomposites were prepared by the sol–gel reaction of zinc acetate dihydrate, which was used as a zinc oxide precursor, with silica gel obtained from the caustic extraction of BLA. The effect of the Zn content (5, 10, and 20 wt%) on the physicochemical characteristics and photocatalytic activity of the nanocomposites was investigated. The results of X-ray diffraction, scanning electron microscopy, gas sorption, and transmission electron microscopy characterization confirmed the mesoporous structure of the composites containing nanoflower-like ZnO (wurtzite) nanoparticles of 10–30 nm in size dispersed on the silica support. Further, the nanocomposites were confirmed to be composed of ZnO/SiO2 by X-ray photoelectron spectroscopy analysis. Meanwhile, diffuse-reflectance UV–visible spectrophotometry analysis of the nanocomposites revealed band gap energies of 3.38–3.39 eV. Of the tested nanocomposites, that containing 10 wt% Zn exhibited the highest decolorization efficiency (99%) and fastest decolorization rate. In addition, the degradation efficiencies were not reduced significantly after five repeated runs, demonstrating the reusability of the nanocomposite catalysts. Therefore, the ZnO/SiO2 nanocomposite obtained from BLA is a promising reusable photocatalyst for the degradation of dye-polluted water.  相似文献   

10.
SnO nanoparticles have been successfully synthesized in the presence of Triton-X 100 (TX-100) surfactant via hydrothermal method for the first time, and the photocatalytic activity under UV and visible light irradiation for the degradation of Methylene Blue (MB) and Rhodamine B (RdB) organic textile dyes was investigated. The structural, morphological and chemical characterizations were investigated by using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), UV–vis. diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) analysis. The results reveal that the addition of surfactant, TX-100, in the precursor solutions leads to reduction in crystallite size with significant changes in morphological structure of SnO nanoparticles. The synthesized SnO nanoparticles show excellent photocatalytic activity under UV or visible light irradiation. MB and RdB dyes degraded completely under UV irradiation after 90 and 150 min, respectively. Also, MB and RdB dyes degraded only 150 min later under visible light illumination with a little amount of photocatalyst (0.8 g/L). Hence, this work explores the facile route to synthesizing efficient SnO nanoparticles for degrading organic compound under both UV and visible light irradiations.  相似文献   

11.
《印度化学会志》2023,100(2):100920
In the present work, silver-doped ZnO (Ag–ZnO NPs) with different concentrations of silver ions (0.3, 0.5, 1.0 and 1.5 mol %) were synthesized by using a simple co-precipitation method. The Ag–ZnO NPs were primarily characterized by XRD, FT-IR, SEM, EDS, TEM, UV–Vis. DRS, PL and BET surface area. The XRD analysis of Ag–ZnO NPs shows a wurtzite structure and optimized Ag–ZnO NPs (1.0 mol %) exhibit a lower crystallite size of 15.96 nm than that of bare ZnO (19.07 nm). Optical study shows a decrease in band gap from 3.13 to 2.97 eV as the concentration of Ag ions increases from 0.3 to 1.5 mol%. TEM images reveal the spherical shape particle with sizes ranging between 10 and 15 nm. From the multipoint BET plot, the surface area of Ag–ZnO NPs found 38.06 m2/gwhich is higher than the ZnO NPs (34.48 m2/g). The photocatalytic study demonstrated that the Ag–ZnO NPs (1.0 mol %) has an excellent photodegradation efficiency of Methyl Orange (96.74%)with a 26% increment as compared to bare ZnO (70.47%). Furthermore, the bactericidal activity of Ag–ZnO NPs (1.0 mol %) was investigated against four different bacterial strains. The results explored that the Gram-negative bacteria (E. coli and P. vulgaris) are more sensitive than Gram-positive (S. aureus and B. cereus) to Ag–ZnO NPs. Overall, the anticipated material is economical and reusable for photodegradation and antibacterial activity.  相似文献   

12.
采用共沉淀-焙烧法合成了一系列不同含量的稀土Ce掺杂的ZnO光催化剂. 利用傅里叶变换红外(FT-IR)光谱、粉末X射线衍射(XRD)、扫描电镜(SEM)、紫外-可见(UV-Vis)光谱、光致发光(PL)谱等技术对所制备的光催化剂进行了系列表征. 以酸性橙II脱色降解为模型反应, 考察了掺杂不同含量的铈及不同焙烧温度对ZnO的物理结构和光催化脱色性能的影响. 结果表明: 掺入质量分数(w)为2%的铈可以明显改善氧化锌表面状态, 有利于产生更多的表面羟基; 同时可以抑制光生电子与光生空穴(e-/h+)的复合, 显著提高光催化脱色活性和光催化稳定性; 焙烧温度对光催化剂的晶体结构、表面性能和光催化活性产生较大影响, 500 °C的焙烧处理使样品的结晶度较高, 同时催化剂颗粒粒径较细, 表面具有丰富的羟基. 但过高的焙烧温度(600-800 °C)将导致催化剂的物理结构发生恶化, 降低光催化性能.  相似文献   

13.
In this study, the photocatalytic degradation of Reactive Blue 81 (RB81) using synthesized NiO-doped ZnO–ZrO2 nanoparticles under UV irradiation was investigated. Then, the products were characterized by Scanning electron microscope (SEM), X-ray diffraction (XRD), and diffuse reflectance spectroscopy (DRS). The removal rate of RB81 using ZnO–ZrO2 after 180?min of irradiation was 96.7%. Nickel oxide (NiO) was used as an additive to ZnO–ZrO2 for improvement of RB81 degradation via photocatalysis process. Photodegradation of RB81 was achieved to 100% using ZnO–ZrO2–NiO nanoparticles with ratio of 1:2:0.3 after 180?min of irradiation. There was a red shift in absorption bands (from 410?nm to 435?nm) observed in increasing of NiO to ZnO–ZrO2 nanoparticle, that it might lead to a higher photocatalytic activity under visible light. Response surface methodology (RSM) was used for optimization of experimental and these results were obtained: solution pH = 3, ZnO–ZrO2–NiO dosage = 15?mg/L, and the initial RB81 concentration = 5?mg/L. The photodegredation of RB81 followed pseudo-first order kinetic according to the Langmuir–Hinshelwood model.  相似文献   

14.
Undoped zinc oxide nanoparticles and Mn (5 atomic % & 10 atomic %) doped zinc oxide nanoparticles were prepared by soft chemical method. Antibacterial, antioxidant and anticancer activities in breast cancer cell line MDAMB231 of prepared nanoparticles were investigated. The nanoparticles were characterized using XRD, SEM, EDAX, UV–Vis, FT-IR, and room temperature PL Analysis. Antimicrobial activity was tested against both gram positive and gram negative human pathogens. The antioxidant potential of prepared nanoparticles was estimated using Phosphomolybdate and DPPH assay. The MTT assay was used for cytotoxicity evaluation of prepared nanoparticles against breast cancer cell line MDAMB231. XRD patterns confirmed the nanoparticles were crystallized hexagonal wurtzite structure with an average size of 38.95 ?nm. The absorption wavelength was observed at 361 ?nm in UV–Vis spectrum of Mn (10 atomic %) doped ZnO nanoparticles. The Mn (5 atomic %) doped ZnO nanoparticles exhibited significant antibacterial activity against the gram negative bacteria Escherichia coli, Klebsiella pneumonia at all concentrations. Undoped zinc oxide nanoparticles and Mn doped zinc oxide nanoparticles were effective against the breast cancer cell line MDAMB231.  相似文献   

15.
《印度化学会志》2022,99(12):100756
In this paper, we report the successful fabrication of a novel dye-sensitized solar cell (DSSCs) using Mg doped ZnO as photoanode and natural dye Terminalia catappa as sensitizer. We synthesized Mg doped ZnO nanoparticles at different Mg concentrations (2%, 4%, 6%, and 8%) by employing a simple solvothermal route. The structural, morphology, composition and optical investigations of synthesized Mg doped ZnO nanoparticles are carried out using XRD, FE-SEM, EDAX, TEM, SAED, FTIR and UV–visible measurements. The XRD results confirmed the formation of hexagonal-wurtzite structure for the Mg doped ZnO nanoparticles and increase of crystalline size with increasing dopant concentration up to 6% is observed. FESEM analysis indicated a gradual change in the surface morphology with increasing Mg concentration and the size of the nanoparticles are slightly reduced at higher Mg concentration. The HRTEM images and SAED pattern also confirmed the formation of wurtzite hexagonal phase of ZnO. The band gap energies calculated from the UV–visible spectra using Tauc's plots indicated decrease of band gap energy with dopant concentration. The DSSCs fabricated using Mg doped ZnO photo-anodes and Terminalia catappa sensitizer showed higher efficiency at higher Mg concentration and observed increase in efficiency is discussed based on slower charge carrier recombination and higher carrier life time as evidenced from the electrochemical impedance analysis.  相似文献   

16.
In the present work, the chalcogen (Se2+)-doped ZnO nanoparticles (SeZO-NPs) were synthesized using sol-gel precipitation method and tested for photocatalytic degradation of Rhodamine B (RhB). X-ray diffraction pattern of SeZO-NPs showed the hexagonal wurtzite crystal structure regardless of Se concentration. The band edge and defect-level emissions of SeZO-NPs were determined by using the photoluminescence spectra with the excitation source of 370 nm. The bandgap, Eg, of SeZO-NPs was measured from diffused reflectance spectroscopy, which increased from 3.22 to 3.26 eV as Se concentration increased from 0 to 10 wt.%. The highest specific surface area and lowest pore size of 5-SeZO-NPs were observed to be 36.42 m2/g and 13.48 nm, respectively. The photocatalytic degradation of SeZO-NPs was measured under the illumination of ultraviolet (UV) light. The double donor (Se) played an important role toward photodegradation of RhB via reducing the recombination of charge carriers. The highest photocatalytic degradation (98.23%) and mineralization were achieved for the sample 5-SeZO (Se: 5 wt.%). The improved photocatalytic performance of 5-SeZO was attributed to the optimum Se dopant concentration for the production of more reactive oxygen species because of effective separation of charge carriers in UV light.  相似文献   

17.
Nanoparticles of cerium oxide (CeO2-NPs), as a metal oxide of rare earth, have found an important role in improving technologies such as polishing, the degradation of harmful industrial dyes and even the treatment of some diseases. Therefore, the development of quick and inexpensive production methods for CeO2-NPs is sought by researchers. In the present study, we report the biosynthesis of CeO2-NPs using aqueous extract of Salvadora persica. Synthesized nanoparticles were investigated through powder X-ray diffraction (PXRD), ultraviolet–visible (UV–vis), Fourier transform infrared, transmission electron microscope (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray and Raman techniques. The UV–vis result shows an absorption peak at 325 nm, which confirms the formation of CeO2-NPs. The band-gap of synthesized nanoparticles (4.1 eV) is higher than in its bulk state. PXRD and Raman show a crystalline fluorite cubic structure for synthesized nanoparticles. The morphology of synthesized nanoparticles shows a uniform and almost spherical shape via TEM and FESEM images. The particles size was estimated in the range of 10–15 nm. Cytotoxic activity of synthesized nanoparticles was determined through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay against a colon (HT-29) cancer cell line. The results did not show any significant cytotoxic effect for synthesized samples even for concentration higher than 800 μg/mL. Hence, CeO2-NPs were synthesized using a natural source; the procedure was rapid with good productivity and biosynthesized nanoparticles were non-toxic.  相似文献   

18.
Low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O nanopowders(NPs)would determine their practical application in purifying wastewater.In this contribution,ZnO NPs were scalably synthesized via the simple reaction of Zn powder with H_2O vapor in autoclave.The structural,morphological and optical properties of the samples were systematically characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectra,transmission electron microscopy,Micro-Raman,photoluminescence,and ultraviolet-visible spectroscopy.The as-prepared Zn O NPs are composed of nanoparticles with 100–150 nm in diameter,and have a small Brunauer-Emmett-Teller surface area of 6.85 m~2/g.The formation of Zn O nanoparticles is relative to the peeling of H_2 release.Furthermore,the product has big strain-stress leading to the red-shift in the band gap of product,and shows a strong green emission centered at 515 nm revealing enough atomic defects in Zn O NPs.As a comparison with P25,the obtained dust gray Zn O NPs have a strong absorbance in the region of 200–700 nm,suggesting the wide wave-band utilization in sunlight.Based on the traits above,the Zn O NPs show excellent photocatalytic activity on the degradation of rhodamine B(Rh-B)under solar light irradiation,close to that under UV irradiation.Importantly,the Zn O NPs could be well recycled in water due to the quick sedimentation in themselves in solution.The low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O NPs endow themselves with promising application in purifying wastewater.  相似文献   

19.
In the work ZnO nanoparticles were prepared by sol-gel method. The catalyst was characterized by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM). The photocatalytic oxidation of anionic surfactant in detergent industries was studied using ZnO nanoparticles with diameter size 20 nm as catalyst on irradiation with UV light. Analysis of kinetic showed that the amount of surfactant photocatalytic degradation can be fitted with pseudo-first-order model and studied photochemical elimination of Linear alkyl benzene sulfonates by the trial-and-error and Taguchi methods. Our experimental design consisted of testing five factors, i.e. dosage of K2S2O8, concentration of surfactant, amount of ZnO, irradiation time, and initial pH. The results showed that photocatalytic degradation of linear alkyl benzene sulfonates was strongly influenced by these parameters.  相似文献   

20.
The Pepper leaves extract acts as a reducing and capping agent in the formation of silver nanoparticles. A UV–Vis spectrum of the aqueous medium containing silver nanoparticles demonstrated a peak at 458 nm corresponding to the plasmon absorbance of rapidly synthesized silver nanoparticles that was characterized by UV–Vis spectrophotometer. The morphology and size of the benign silver nanoparticles were carried out by the transmission electron microscope (TEM) and field emission scanning electron microscope (FE-SEM). The sizes of the synthesized silver nanoparticles were found to be in the range of 5–60 nm. The structural characteristics of biomolecules hosted silver nanoparticles were studied by X-ray diffraction. The chemical composition of elements present in the solution was determined by energy dispersive spectrum. The FTIR analysis of the nanoparticles indicated the presence of proteins, which may be acting as capping agents around the nanoparticles. This study reports that synthesis is useful to avoid toxic chemicals with adverse effects in medical applications rather than physical and chemical methods.  相似文献   

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