Silver nanoparticles are considerecl as good antimicrobial agent. AgNPs were synthesized by mixing silver nitrate solution with citrus sinesb extract for 2 h at 37 and analyzed by UV-visible spectra, SEM, XRD, and FT...Silver nanoparticles are considerecl as good antimicrobial agent. AgNPs were synthesized by mixing silver nitrate solution with citrus sinesb extract for 2 h at 37 and analyzed by UV-visible spectra, SEM, XRD, and FTIR. AgNPs were tested against B. subtilis, Shigello, S. oureus, ond E. coli. Minimum inhibitory concentration of AgNPs was 20 I^g/mL for B. subtilis and Shigello and 30 I^g/mL for S. oureus and E. coll. Antibiofilm activity （80% to 90%） was observed at 25 IJg/mL. AgNPs were stable for five months with sustained an＇timicrobial activity. Biosynthesized AgNPs can bE： used to inhibit food poisoning microbial growth.展开更多
In this study, rose-like nickel oxide （NiO） nanoparticles with diameters of 400-500 nm are prepared on ITO glass substrates by simple electrodeposition in NiSO46H20 solution at room temperature followed by oxidation...In this study, rose-like nickel oxide （NiO） nanoparticles with diameters of 400-500 nm are prepared on ITO glass substrates by simple electrodeposition in NiSO46H20 solution at room temperature followed by oxidation in air. Scanning electron microscopy, x-ray diffraction and a transmission electron microscope are used for analyses of the NiO nanoparticles. The ethanol gas sensitivity of these nanoparticles is studied. The results indicate that the rose-like NiO nanoparticles could be used for the fabrication of ethanol gas sensors to monitor the low concentration of ethanol gas in air. Furthermore, at 5 ppm, the NiO nanorose-based sensors show a high response to ethanol （Rg/Ra = 8.4）.展开更多
CuO nanoparticles were synthesized by using microreactors made of Triton X-100/n-hextnol/cyclohexane/water W/O microemulsion system. Basic synthesis parameters were determined. The results of thermo gravimetric/differ...CuO nanoparticles were synthesized by using microreactors made of Triton X-100/n-hextnol/cyclohexane/water W/O microemulsion system. Basic synthesis parameters were determined. The results of thermo gravimetric/differential thermal analysis（TG/DTA） of the precursor products indicated that the proper calcination temperature was about 500 ℃. The nanoparticles were characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM） and UV-visible spectra. It was indicated that the grain size was highly dependent on the ratio of water to surfactant（R）. With the R value increasing, the particles size became larger.展开更多
Rare-earth stannate（Ln_2Sn_2O_7（Ln = Y, La–Lu）） nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200°C within 60 min. The products were well char...Rare-earth stannate（Ln_2Sn_2O_7（Ln = Y, La–Lu）） nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200°C within 60 min. The products were well characterized. The effect of reaction parameters such as temperature, reaction time, p H value, and alkali source on the preparation was investigated. The results revealed that the p H value plays an important role in the formation process of gadolinium stannate（Gd_2Sn_2O_7） nanoparticles. By contrast, the alkali source had no effect on the phase composition or morphology of the final product. Uniform and sphere-like nanoparticles with an average size of approximately 50 nm were obtained at the p H value of 11.5. A possible formation mechanism was briefly proposed. Gd_2Sn_2O_7：Eu^（3＋） nanoparticles displayed strong orange-red emission. Magnetic measurements revealed that Gd_2Sn_2O_7 nanoparticles were paramagnetic. The other rare-earth stannate Ln_2Sn_2O_7（Ln = Y, La–Lu） nanocrystals were prepared by similar approaches.展开更多
FePt nanoparticles in mesoporous silica are fabricated by a simple stepwise synthesis strategy.A pre-annealing temperature-dependent coercivity-ageing effect in FePt nanoparticles is observed at room temperature.For f...FePt nanoparticles in mesoporous silica are fabricated by a simple stepwise synthesis strategy.A pre-annealing temperature-dependent coercivity-ageing effect in FePt nanoparticles is observed at room temperature.For facecentered cubic（fcc）structured FePt nanoparticles,the ageing effect is sensitive to the pre-annealing temperature,especially when the temperature is close to the phase-transition.The special magnetic behavior of FePt nanoparticles reveals that the physical properties gradually change between fee and face-centered tetragonal structures,and will deepen our understanding of the mechanism of such magnetism in FePt nanoparticles.展开更多
Cu_2NiSnS_4 nanoparticles were prepared for the first time using a facile solid-phase process at a temperature of 180 °C. The crystalline structure, morphology and optical properties of the Cu_2NiSnS_4 nanopartic...Cu_2NiSnS_4 nanoparticles were prepared for the first time using a facile solid-phase process at a temperature of 180 °C. The crystalline structure, morphology and optical properties of the Cu_2NiSnS_4 nanoparticles were characterized by means of X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), transmission electron microscope(TEM) and ultraviolet-visible(UV-vis) spectrophotometer. The band gap and conversion efficiency of Cu_2NiSnS_4 nanoparticles were studied at various temperature. The results showed that the Cu_2NiSnS_4 nanoparticles exhibited an optimum band gap of 1.58 e V and a conversion efficiency of 0.64% at 180 °C, indicating that it maybe be useful in low-cost thin film solar cells.展开更多
To investigate the effect purification plays on nanoparticle (NP) synthesis and catalytic activity, three copies of Pd4 (TSNAVHPTLRHL) fused to the N-terminus of Green Fluorescent Protein (GFP) was produced recombinan...To investigate the effect purification plays on nanoparticle (NP) synthesis and catalytic activity, three copies of Pd4 (TSNAVHPTLRHL) fused to the N-terminus of Green Fluorescent Protein (GFP) was produced recombinantly and its characteristics pre and post purification was assessed. An E. coli expression system was employed, and purification was performed with Immobilized Metal Affinity Column (IMAC). Transmission electron microscopy (TEM) was utilized to examine the morphology of NPs synthesized with an enriched protein sample and ImageJ was used to determine the average size to be 2.44 nm. The turnover frequency of fabricated NP from the purified protein was analyzed by a model Suzuki-Miyaura coupling reactions and determined to be 33,000 hr<sup>-1</sup>. This value is three times higher than the turnover frequency when crude lysate containing (Pd4)<sub>3</sub>-GFP was used during NP synthesis. This result shows that enrichment enhanced the catalytic activity of NP.展开更多
The formation of BaTiO3 nanoparticles via the reaction of BaCl2, TiCl4 and NaOH in aqueous solution has been systematically studied. The formation of BaTiO3 from the ionic precursors has been elucidated to be a very r...The formation of BaTiO3 nanoparticles via the reaction of BaCl2, TiCl4 and NaOH in aqueous solution has been systematically studied. The formation of BaTiO3 from the ionic precursors has been elucidated to be a very rapid process, occurring at temperature higher than 60℃. Furthermore, the particle size could be controlled by the proper selection of the synthesis conditions (e.g. reactant concentration of 0.5—1.0mol·L-1, temperature of 80— 95℃ and pH≥13). A two-step precipitation mechanism was proposed. The first stage of the synthesis involved the formation of amorphous Ti-rich gel phase. The second stage of the synthesis was the reaction between the amor-phous phase and the solution-based Ba2+ ions, which led to the crystallization of BaTiO3. Based on the particle for-mation mechanism, a novel method, high gravity reactive precipitation, was proposed and used to mass production of BaTiO3 of average particle size of about 60 nm and with narrow particle size distribution. Because it could break up the amorphous Ti-rich gel into small pieces, intensify mass transfer, promote the reaction rate of amorphous Ti-rich gel with Ba2+ ions.展开更多
Gold nanoparticles （AuNPs） functionalized with supramolecular macrocycles are versatile and diverse hybrid nanomaterials, which combine and enhance the characteristics of the two components. In this mini-review, we ...Gold nanoparticles （AuNPs） functionalized with supramolecular macrocycles are versatile and diverse hybrid nanomaterials, which combine and enhance the characteristics of the two components. In this mini-review, we summarize the recent research progress on the synthesis and assembly of AuNPs functionalized with different supramolecular macrocyclic compounds, i.e., crown ethers, cyclophanes, cyclodextrins （CDs）, cucurbit[n]urils （CB[n]）, calix[n]arenes, and pillar[n]arenes （PIn]A）. Meanwhile, applications of these supramolecular hybrid nanomaterials in the fields of sensors, biomedicine and plasmonic devices are also presented.展开更多
A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and ...A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and aqueous species and a 0ebye-Huckel coefficients model to represent solution nonideality. The method has been used to generate phase stability diagrams that indicate the ranges of pH and reagent concentrations, for which various species predominate in the system at a given temperature. Also, yield diagrams have been constructed that indicate the concentration, pH and temperature conditions for which different yields of crystalline BaTiO3 can be obtained. The stability and yield diagrams have been used to predict the optimum synthesis conditions (e.g., reagent concentrations, pH and temperature). Subsequently, these predictions have been experimentally verified. As a result, phase-pure perovskite BaTiO3 has been obtained at temperature ranging from 55 to 85℃ using BaCl2, TiCl4 as a source for Ba and Ti, and NaOH as a precipitator.展开更多
A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sampl...A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sample was typical of superparamagnetic material.The samples were characterized by transmission electron microscope,and it is found that the particles are of small size.The Fe_3O_4/GO MNPs were further used as an adsorbent to remove Rhodamine B.The effects of initial pH of the solution,the dosage of adsorbent,temperature,contact time and the presence of interfering dyes on adsorption performance were investigated as well.The adsorption equilibrium and kinetics data were fitted well with the Freundlich isotherm and the pseudosecond-order kinetic model respectively.The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption of Rhodamine B.And the adsorption process was endothermic in nature.Furthermore,the magnetic composite with a high adsorption capacity of Rhodamine B could be effectively and simply separated using an external magnetic field.And the used particles could be regenerated and recycled easily.The magnetic composite could find potential applications for the removal of dye pollutants.展开更多
We report a rapid method of green chemistry approach for synthesis of gold nanoparticles（AuNPs）using Lagerstroemia speciosa leaf extract（LSE）. L. speciosa plant extract is known for its effective treatment of diab...We report a rapid method of green chemistry approach for synthesis of gold nanoparticles（AuNPs）using Lagerstroemia speciosa leaf extract（LSE）. L. speciosa plant extract is known for its effective treatment of diabetes and kidney related problems. The green synthesis of Au NPs was complete within 30 min at 25°C. The same could also be achieved within 2 min at a higher reaction temperature（80°C）. Both UV–visible spectroscopy and transmission electron microscopy results suggest that the morphology and size distribution of Au NPs are dependent on the pH of gold solution,gold concentration,volume of LSE,and reaction time and temperature. Comparison between Fourier transform infrared spectroscopy（FT-IR）spectra of LSE and the synthesized Au NPs indicate an active role of polyphenolic functional groups（from gallotannins,lagerstroemin,and corosolic acid）in the green synthesis and capping of Au NPs. The green route synthesized Au NPs show strong photocatalytic activity in the reduction of dyes viz.,methylene blue,methyl orange,bromophenol blue and bromocresol green,and 4-nitrophenol under visible light in the presence of Na BH4. The non-toxic and cost effective LSE mediated Au NPs synthesis proposed in this study is extremely rapid compared to the other reported methods that require hours to days for complete synthesis of Au NPs using various plant extracts. Strong and stable photocatalytic behavior makes Au NPs attractive in environmental applications,particularly in the reduction of organic pollutants in wastewater.展开更多
This work reports a facile and efficient seed-mediated method for the synthesis of dendritic platinum （Pt） nanoparticles （NPs） at low temperatures of 55-60 ℃ in water, using L-ascorbic acid as a reducing agent an...This work reports a facile and efficient seed-mediated method for the synthesis of dendritic platinum （Pt） nanoparticles （NPs） at low temperatures of 55-60 ℃ in water, using L-ascorbic acid as a reducing agent and sodium citrate as a capping agent. It is found that the dendritic Pt NPs （10-150 nm） are composed of tiny Pt nanocrystals, which nucleate and grow through the introduced smaller Pt seeds with diameters of 3-5 nm. Further investigation shows that the dendritic Pt nanostructures display excellent catalytic performance in an aqueous-phase aromatic ketone hydrogenation reaction, including： （i） acetophenone conversion rate of 〉 90%, with smaller dendritic Pt NPs （10-46 nm） offering a higher conversion efficiency; （ii） high chemoselectivity toward carbonyl group （90.6%-91.5%）, e.g., the selectivity to l-phenylethanol is -90.1% with nearly 100% acetophenone conversion for 10 nm dendritic Pt NPs within 60 rain, under mild reaction conditions （20 ℃, 1.5 bar H2 pressure, and 1.5 tool% catalyst）. The high catalytic activity, selectivity and stability of the dendritic Pt nanostructures under the organic solvent-free conditions make them promising for many potential applications in green catalytic conversion of hydrophilic biomass derived compounds.展开更多
Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes, are studies in the direct synthesis of H2O2. They are prepared by depositing Pd in two ways：（i） reduct...Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes, are studies in the direct synthesis of H2O2. They are prepared by depositing Pd in two ways：（i） reduction with N2H4 in an ultrasonic bath and（ii） by impregnation-deposition. The first preparation leads to larger particles, with average size of around 11 nm, while the second preparation leads to smaller particles, with average size around 4 nm. The catalytic membranes were tested as prepared, after thermal treatment in air and after further pre-reduction with H2 in mild（100 ℃） conditions. Samples were characterized by TEM, CO-chemisorption monitored by DRIFTS method and TPR, while catalytic tests have been performed in a semi-batch recirculation membrane reactor. Experimental catalytic results were analysed using two kinetics models to derive the reaction constants for the parallel and consecutive reactions of the kinetic network. Smaller particles of Pd show lower selectivity due to the higher rate of parallel combustion, even if the better dispersion of Pd and thus higher metal surface area in the sample lead to a productivity in H2O2 similar or even higher than the sample with the larger Pd particles. Independently on the presence of smaller or larger Pd nanoparticles, an oxidation treatment leads to a significant enhancement in the productivity, although the catalyst progressively reduces during the catalytic process. The inhibition of the parallel combustion reaction（to water） induced from the calcination treatment remains after the in-situ reduction of the oxidized Pd species formed during the pre-treatment.This is likely due to the elimination of defect sites which dissociatively activate oxygen, and tentatively attributed to Pd sites able to give three- and four-fold coordination of CO.展开更多
Microflowers made of interconnected MnO2 nanosheets have been successfully synthesized in a microwave reactor through a hydrothermal reduction of KMnO4 with aqueous HCI at elevated temperatures in the presence of supe...Microflowers made of interconnected MnO2 nanosheets have been successfully synthesized in a microwave reactor through a hydrothermal reduction of KMnO4 with aqueous HCI at elevated temperatures in the presence of superparamagnetic Fe3O4SiO2 core-shell nanoparticles.Due to the chemical compatibility between SiO2 and MnO2,the heterogeneous reaction leads to the spontaneous encapsulation of the Fe3O4@SiO2 core-shell nanoparticles in the MnO2 microflowers.The resulting hybrid particles exhibit multiple properties including high surface area associated with the MnO2nanosheets and superparamagnetism originated from the Fe3O4@SiO2 core-shell nanoparticles.which are beneficial for applications requiring both high surface area and magnetic separation.展开更多
Rational designing and controlling of nanostructures is a key factor in realizing appropriate properties required for the high-performance energy fields. In the present study, hollow Sn O2@C nanoparticles（NPs） with ...Rational designing and controlling of nanostructures is a key factor in realizing appropriate properties required for the high-performance energy fields. In the present study, hollow Sn O2@C nanoparticles（NPs） with a mean size of 50 nm have been synthesized in large-scale via a facile hydrothermal approach.The morphology and composition of as-obtained products were studied by various characterized techniques. As an anode material for lithium ion batteries（LIBs）, the as-prepared hollow Sn O2@C NPs exhibit significant improvement in cycle performances. The discharge capacity of lithium battery is as high as 370 m Ah g 1, and the current density is 3910 m A g 1（5 C） after 573 cycles. Furthermore, the capacity recovers up to 1100 m Ah g 1at the rate performances in which the current density is recovered to 156.4 m A g 1（0.2 C）. Undoubtedly, sub-100 nm Sn O2@C NPs provide significant improvement to the electrochemical performance of LIBs as superior-anode nanomaterials, and this carbon coating strategy can pave the way for developing high-performance LIBs.展开更多
ZnO nanoparticles（ZnO NPs） were synthesized by chemical method（coprecipitation） and biological method using aqueous extracts of garlic（Allium sativum）,rosemary（Rosmarinus officinalis） and basil（Ocimum basili...ZnO nanoparticles（ZnO NPs） were synthesized by chemical method（coprecipitation） and biological method using aqueous extracts of garlic（Allium sativum）,rosemary（Rosmarinus officinalis） and basil（Ocimum basilicum）.The influence of plant extract on the antibacterial and antioxidant activities of green synthesized nanoparticles was investigated.The X-ray diffraction studies reveal that all ZnO samples have hexagonal wurtzite structure.The particle size of ZnO NPs estimated by transmission electron microscopy analysis（between 14 and 27 nm） varies depending on the synthesis method of nanoparticles and the type of extracts from the plants used.The functional groups involved in the biosynthetic procedure were evidenced by Fourier transform infrared spectroscopy.The presence of Mn^（2＋）ions,Zn vacancy complexes and oxygen vacancies in ZnO samples was highlighted by electron paramagnetic resonance spectroscopy.The green synthesized ZnO NPs have shown a good bactericidal activity against Staphylococcus aureus,Bacillus subtilis,Listeria monocytogenes,Escherichia coli,Salmonella typhimurium and Pseudomonas aeruginosa bacterial strains.ZnO NPs synthesized using extracts of the selected plant species have been found to exhibit more enhanced antibacterial and antioxidant activities as compared to chemical ZnO NPs.展开更多
It is reported that the highly dispersed Pt nanoparticles on carbon nanotubes can be synthesized under mild conditions by in situ plasma treatment.The carbon nanotube was pretreated by O_2 plasma to transform into oxi...It is reported that the highly dispersed Pt nanoparticles on carbon nanotubes can be synthesized under mild conditions by in situ plasma treatment.The carbon nanotube was pretreated by O_2 plasma to transform into oxide carbon nanotubes（O-CNTs）,and then it was mixed with the precursors（the mixture of H_2 PtCl_6and PdCl_6）.After that,the O-CNTs and the precursors were simultaneously treated by H_2 plasma.The precursors were transformed into Pt-Pd nanoparticles（NPs）and the O-CNTs transformed into CNT.The synthesized CNT-based Pt-Pd nanoparticles were characterized by scanning electron microscopy,transmission electron microscopy,X-ray diffraction and X-ray photoelectron spectroscopy.All the analysis showed that the Pt-Pd nanoparticles were deposited on CNT as a form of face-centered cubical structure.展开更多
Development of environmentally benign methods for synthesis of nanoparticles is an evolving important branch of nanotechnology.In the present study we report a green method for synthesis of stable silver nanoparticles...Development of environmentally benign methods for synthesis of nanoparticles is an evolving important branch of nanotechnology.In the present study we report a green method for synthesis of stable silver nanoparticles(SNPs)from aqueous leaf extract of Syzygium alternifolium an endemic medicinal plant to Southern Eastern Ghats.These green synthesized nanoparticles are characterized by using UV-VIS spectroscopy,FTIR,XRD,AFM,SEM with EDAX and TEM.The colour change from yellow to grey is observed upon synthesis and 448 nm peak was obtained from UV-VIS spectroscopic analysis.FTIR spectroscopic studies confirms that phenols and proteins of leaf extract is main responsible for capping and stabilization of these SNPs.Crystallographic studies from XRD indicated the SNPs are crystalline in nature and owing 44 nm size.High resolution and magnification studies with AFM,SEM and TEM analysis revealed that the nanoparticles are spherical in shape having the size range from 7 to 44 nm.EDAX pattern of synthesized SNPs showed 47.28 weight percentage of Ag metal in the sample indicate the purity of sample.Further,the antimicrobial studies of these green synthesized SNPs show high toxicity towards different bacterial and fungal isolates.The results revealed that the selected medicinal plant possess the potentiality towards the synthesis of narrow range nanoparticles also combat with the pathogens.展开更多
Monodisperse Au nanoparticles(NPs)have been synthesized at room temperature via a burst nucleation of Au upon injection of the reducing agent t-butylamine-borane complex into a 1,2,3,4-tetrahydronaphthalene solution o...Monodisperse Au nanoparticles(NPs)have been synthesized at room temperature via a burst nucleation of Au upon injection of the reducing agent t-butylamine-borane complex into a 1,2,3,4-tetrahydronaphthalene solution of HAuCl4·3H2O in the presence of oleylamine.The as-synthesized Au NPs show size-dependent surface plasmonic properties between 520 and 530 nm.They adopt an icosahedral shape and are polycrystalline with multiple-twinned structures.When deposited on a graphitized porous carbon support,the NPs are highly active for CO oxidation,showing 100%CO conversion at-45°C.展开更多
文摘Silver nanoparticles are considerecl as good antimicrobial agent. AgNPs were synthesized by mixing silver nitrate solution with citrus sinesb extract for 2 h at 37 and analyzed by UV-visible spectra, SEM, XRD, and FTIR. AgNPs were tested against B. subtilis, Shigello, S. oureus, ond E. coli. Minimum inhibitory concentration of AgNPs was 20 I^g/mL for B. subtilis and Shigello and 30 I^g/mL for S. oureus and E. coll. Antibiofilm activity （80% to 90%） was observed at 25 IJg/mL. AgNPs were stable for five months with sustained an＇timicrobial activity. Biosynthesized AgNPs can bE： used to inhibit food poisoning microbial growth.
基金Supported by the Natural Science Foundation of Gansu Province under Grant No 1107RJZA090the Foundation of State Key Library of Functional Materials for Informatics of Shanghai Institute of Microsystem and Information Technologythe National Natural Science Foundation of China under Grant No 61204106
文摘In this study, rose-like nickel oxide （NiO） nanoparticles with diameters of 400-500 nm are prepared on ITO glass substrates by simple electrodeposition in NiSO46H20 solution at room temperature followed by oxidation in air. Scanning electron microscopy, x-ray diffraction and a transmission electron microscope are used for analyses of the NiO nanoparticles. The ethanol gas sensitivity of these nanoparticles is studied. The results indicate that the rose-like NiO nanoparticles could be used for the fabrication of ethanol gas sensors to monitor the low concentration of ethanol gas in air. Furthermore, at 5 ppm, the NiO nanorose-based sensors show a high response to ethanol （Rg/Ra = 8.4）.
基金Funded by the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20132124120003)
文摘CuO nanoparticles were synthesized by using microreactors made of Triton X-100/n-hextnol/cyclohexane/water W/O microemulsion system. Basic synthesis parameters were determined. The results of thermo gravimetric/differential thermal analysis（TG/DTA） of the precursor products indicated that the proper calcination temperature was about 500 ℃. The nanoparticles were characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM） and UV-visible spectra. It was indicated that the grain size was highly dependent on the ratio of water to surfactant（R）. With the R value increasing, the particles size became larger.
基金financially supported by the National Natural Science Foundation of China (Nos. 21641008 and 91622105)the Jiangxi Provincial Department of Science and Technology (Nos. 20161BAB203083 and 20151BDH80049)
文摘Rare-earth stannate（Ln_2Sn_2O_7（Ln = Y, La–Lu）） nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200°C within 60 min. The products were well characterized. The effect of reaction parameters such as temperature, reaction time, p H value, and alkali source on the preparation was investigated. The results revealed that the p H value plays an important role in the formation process of gadolinium stannate（Gd_2Sn_2O_7） nanoparticles. By contrast, the alkali source had no effect on the phase composition or morphology of the final product. Uniform and sphere-like nanoparticles with an average size of approximately 50 nm were obtained at the p H value of 11.5. A possible formation mechanism was briefly proposed. Gd_2Sn_2O_7：Eu^（3＋） nanoparticles displayed strong orange-red emission. Magnetic measurements revealed that Gd_2Sn_2O_7 nanoparticles were paramagnetic. The other rare-earth stannate Ln_2Sn_2O_7（Ln = Y, La–Lu） nanocrystals were prepared by similar approaches.
基金Supported by the Natural Science Foundation of Zhejiang Province under Grant No LY15E010002the National Natural Science Foundation of China under Grant No 51671139
文摘FePt nanoparticles in mesoporous silica are fabricated by a simple stepwise synthesis strategy.A pre-annealing temperature-dependent coercivity-ageing effect in FePt nanoparticles is observed at room temperature.For facecentered cubic（fcc）structured FePt nanoparticles,the ageing effect is sensitive to the pre-annealing temperature,especially when the temperature is close to the phase-transition.The special magnetic behavior of FePt nanoparticles reveals that the physical properties gradually change between fee and face-centered tetragonal structures,and will deepen our understanding of the mechanism of such magnetism in FePt nanoparticles.
基金supported by the Fundamental Research Funds for the Central Public Welfare Research Institutes (No.TKS20200311)。
文摘Cu_2NiSnS_4 nanoparticles were prepared for the first time using a facile solid-phase process at a temperature of 180 °C. The crystalline structure, morphology and optical properties of the Cu_2NiSnS_4 nanoparticles were characterized by means of X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), transmission electron microscope(TEM) and ultraviolet-visible(UV-vis) spectrophotometer. The band gap and conversion efficiency of Cu_2NiSnS_4 nanoparticles were studied at various temperature. The results showed that the Cu_2NiSnS_4 nanoparticles exhibited an optimum band gap of 1.58 e V and a conversion efficiency of 0.64% at 180 °C, indicating that it maybe be useful in low-cost thin film solar cells.
文摘To investigate the effect purification plays on nanoparticle (NP) synthesis and catalytic activity, three copies of Pd4 (TSNAVHPTLRHL) fused to the N-terminus of Green Fluorescent Protein (GFP) was produced recombinantly and its characteristics pre and post purification was assessed. An E. coli expression system was employed, and purification was performed with Immobilized Metal Affinity Column (IMAC). Transmission electron microscopy (TEM) was utilized to examine the morphology of NPs synthesized with an enriched protein sample and ImageJ was used to determine the average size to be 2.44 nm. The turnover frequency of fabricated NP from the purified protein was analyzed by a model Suzuki-Miyaura coupling reactions and determined to be 33,000 hr<sup>-1</sup>. This value is three times higher than the turnover frequency when crude lysate containing (Pd4)<sub>3</sub>-GFP was used during NP synthesis. This result shows that enrichment enhanced the catalytic activity of NP.
基金Supported by the National Natural Science Foundation of China (Nos.20236020, 20325621), the Talent Training Program of theBeijing City (No.9558103500), and the Fok Ying Tung Foundation (No.81063).
文摘The formation of BaTiO3 nanoparticles via the reaction of BaCl2, TiCl4 and NaOH in aqueous solution has been systematically studied. The formation of BaTiO3 from the ionic precursors has been elucidated to be a very rapid process, occurring at temperature higher than 60℃. Furthermore, the particle size could be controlled by the proper selection of the synthesis conditions (e.g. reactant concentration of 0.5—1.0mol·L-1, temperature of 80— 95℃ and pH≥13). A two-step precipitation mechanism was proposed. The first stage of the synthesis involved the formation of amorphous Ti-rich gel phase. The second stage of the synthesis was the reaction between the amor-phous phase and the solution-based Ba2+ ions, which led to the crystallization of BaTiO3. Based on the particle for-mation mechanism, a novel method, high gravity reactive precipitation, was proposed and used to mass production of BaTiO3 of average particle size of about 60 nm and with narrow particle size distribution. Because it could break up the amorphous Ti-rich gel into small pieces, intensify mass transfer, promote the reaction rate of amorphous Ti-rich gel with Ba2+ ions.
基金the National Natural Science Foundation of China(No. 21272093)the Research Fund for the Doctoral Program of Higher Education of China(No.20120061120117)the Independent Innovation Research Program from the State Key Laboratory of Supramolecular Structure and Materials for financial support
文摘Gold nanoparticles （AuNPs） functionalized with supramolecular macrocycles are versatile and diverse hybrid nanomaterials, which combine and enhance the characteristics of the two components. In this mini-review, we summarize the recent research progress on the synthesis and assembly of AuNPs functionalized with different supramolecular macrocyclic compounds, i.e., crown ethers, cyclophanes, cyclodextrins （CDs）, cucurbit[n]urils （CB[n]）, calix[n]arenes, and pillar[n]arenes （PIn]A）. Meanwhile, applications of these supramolecular hybrid nanomaterials in the fields of sensors, biomedicine and plasmonic devices are also presented.
基金Supported by the National Natural Science Foundation of China (No. 20236020, No. 20325621)863 Hi-Technology Research and Development Program of China (No. 2001AA325014)the Talent Training Program of the Beijing City (No. 9558103500)the Fok Ying Tung Foundation (No. 81063).
文摘A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and aqueous species and a 0ebye-Huckel coefficients model to represent solution nonideality. The method has been used to generate phase stability diagrams that indicate the ranges of pH and reagent concentrations, for which various species predominate in the system at a given temperature. Also, yield diagrams have been constructed that indicate the concentration, pH and temperature conditions for which different yields of crystalline BaTiO3 can be obtained. The stability and yield diagrams have been used to predict the optimum synthesis conditions (e.g., reagent concentrations, pH and temperature). Subsequently, these predictions have been experimentally verified. As a result, phase-pure perovskite BaTiO3 has been obtained at temperature ranging from 55 to 85℃ using BaCl2, TiCl4 as a source for Ba and Ti, and NaOH as a precipitator.
基金Supported by the National Natural Science Foundation of China(21107143,21207033)the Fundamental Research Funds for the Central Universities,South-Central University for Nationalities(CZY15003)
文摘A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sample was typical of superparamagnetic material.The samples were characterized by transmission electron microscope,and it is found that the particles are of small size.The Fe_3O_4/GO MNPs were further used as an adsorbent to remove Rhodamine B.The effects of initial pH of the solution,the dosage of adsorbent,temperature,contact time and the presence of interfering dyes on adsorption performance were investigated as well.The adsorption equilibrium and kinetics data were fitted well with the Freundlich isotherm and the pseudosecond-order kinetic model respectively.The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption of Rhodamine B.And the adsorption process was endothermic in nature.Furthermore,the magnetic composite with a high adsorption capacity of Rhodamine B could be effectively and simply separated using an external magnetic field.And the used particles could be regenerated and recycled easily.The magnetic composite could find potential applications for the removal of dye pollutants.
文摘We report a rapid method of green chemistry approach for synthesis of gold nanoparticles（AuNPs）using Lagerstroemia speciosa leaf extract（LSE）. L. speciosa plant extract is known for its effective treatment of diabetes and kidney related problems. The green synthesis of Au NPs was complete within 30 min at 25°C. The same could also be achieved within 2 min at a higher reaction temperature（80°C）. Both UV–visible spectroscopy and transmission electron microscopy results suggest that the morphology and size distribution of Au NPs are dependent on the pH of gold solution,gold concentration,volume of LSE,and reaction time and temperature. Comparison between Fourier transform infrared spectroscopy（FT-IR）spectra of LSE and the synthesized Au NPs indicate an active role of polyphenolic functional groups（from gallotannins,lagerstroemin,and corosolic acid）in the green synthesis and capping of Au NPs. The green route synthesized Au NPs show strong photocatalytic activity in the reduction of dyes viz.,methylene blue,methyl orange,bromophenol blue and bromocresol green,and 4-nitrophenol under visible light in the presence of Na BH4. The non-toxic and cost effective LSE mediated Au NPs synthesis proposed in this study is extremely rapid compared to the other reported methods that require hours to days for complete synthesis of Au NPs using various plant extracts. Strong and stable photocatalytic behavior makes Au NPs attractive in environmental applications,particularly in the reduction of organic pollutants in wastewater.
基金the financial support of the Australian Research Council (ARC) projectsUSyd Early Career Researcher Scheme+2 种基金Major Equipment Schemethe scholarships provided by China Scholarship Council (CSC)the Commonwealth Scientific and Industrial Research Organization (CSIRO) OCE Top-up Scholarship
文摘This work reports a facile and efficient seed-mediated method for the synthesis of dendritic platinum （Pt） nanoparticles （NPs） at low temperatures of 55-60 ℃ in water, using L-ascorbic acid as a reducing agent and sodium citrate as a capping agent. It is found that the dendritic Pt NPs （10-150 nm） are composed of tiny Pt nanocrystals, which nucleate and grow through the introduced smaller Pt seeds with diameters of 3-5 nm. Further investigation shows that the dendritic Pt nanostructures display excellent catalytic performance in an aqueous-phase aromatic ketone hydrogenation reaction, including： （i） acetophenone conversion rate of 〉 90%, with smaller dendritic Pt NPs （10-46 nm） offering a higher conversion efficiency; （ii） high chemoselectivity toward carbonyl group （90.6%-91.5%）, e.g., the selectivity to l-phenylethanol is -90.1% with nearly 100% acetophenone conversion for 10 nm dendritic Pt NPs within 60 rain, under mild reaction conditions （20 ℃, 1.5 bar H2 pressure, and 1.5 tool% catalyst）. The high catalytic activity, selectivity and stability of the dendritic Pt nanostructures under the organic solvent-free conditions make them promising for many potential applications in green catalytic conversion of hydrophilic biomass derived compounds.
文摘Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes, are studies in the direct synthesis of H2O2. They are prepared by depositing Pd in two ways：（i） reduction with N2H4 in an ultrasonic bath and（ii） by impregnation-deposition. The first preparation leads to larger particles, with average size of around 11 nm, while the second preparation leads to smaller particles, with average size around 4 nm. The catalytic membranes were tested as prepared, after thermal treatment in air and after further pre-reduction with H2 in mild（100 ℃） conditions. Samples were characterized by TEM, CO-chemisorption monitored by DRIFTS method and TPR, while catalytic tests have been performed in a semi-batch recirculation membrane reactor. Experimental catalytic results were analysed using two kinetics models to derive the reaction constants for the parallel and consecutive reactions of the kinetic network. Smaller particles of Pd show lower selectivity due to the higher rate of parallel combustion, even if the better dispersion of Pd and thus higher metal surface area in the sample lead to a productivity in H2O2 similar or even higher than the sample with the larger Pd particles. Independently on the presence of smaller or larger Pd nanoparticles, an oxidation treatment leads to a significant enhancement in the productivity, although the catalyst progressively reduces during the catalytic process. The inhibition of the parallel combustion reaction（to water） induced from the calcination treatment remains after the in-situ reduction of the oxidized Pd species formed during the pre-treatment.This is likely due to the elimination of defect sites which dissociatively activate oxygen, and tentatively attributed to Pd sites able to give three- and four-fold coordination of CO.
基金supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under Contract No.DE-AC02-06CH11357
文摘Microflowers made of interconnected MnO2 nanosheets have been successfully synthesized in a microwave reactor through a hydrothermal reduction of KMnO4 with aqueous HCI at elevated temperatures in the presence of superparamagnetic Fe3O4SiO2 core-shell nanoparticles.Due to the chemical compatibility between SiO2 and MnO2,the heterogeneous reaction leads to the spontaneous encapsulation of the Fe3O4@SiO2 core-shell nanoparticles in the MnO2 microflowers.The resulting hybrid particles exhibit multiple properties including high surface area associated with the MnO2nanosheets and superparamagnetism originated from the Fe3O4@SiO2 core-shell nanoparticles.which are beneficial for applications requiring both high surface area and magnetic separation.
基金the Program for the NSFC (Nos. 51302325, 51201115, 51471121)New Century Excellent Talents in University (No. NCET-12-0553)+4 种基金Program for Shenghua Overseas Talent (No. 1681-7607030005) from Central South UniversityHubei Provincial Natural Science Foundation (No. 2014CFB261)the partial financial support from the Open-End Fund for the Valuable and Precision Instruments of Central South University (No. CSUZC2014032)Fundamental Research Funds for the Central Universities (No. 2042015kf0184)Wuhan University
文摘Rational designing and controlling of nanostructures is a key factor in realizing appropriate properties required for the high-performance energy fields. In the present study, hollow Sn O2@C nanoparticles（NPs） with a mean size of 50 nm have been synthesized in large-scale via a facile hydrothermal approach.The morphology and composition of as-obtained products were studied by various characterized techniques. As an anode material for lithium ion batteries（LIBs）, the as-prepared hollow Sn O2@C NPs exhibit significant improvement in cycle performances. The discharge capacity of lithium battery is as high as 370 m Ah g 1, and the current density is 3910 m A g 1（5 C） after 573 cycles. Furthermore, the capacity recovers up to 1100 m Ah g 1at the rate performances in which the current density is recovered to 156.4 m A g 1（0.2 C）. Undoubtedly, sub-100 nm Sn O2@C NPs provide significant improvement to the electrochemical performance of LIBs as superior-anode nanomaterials, and this carbon coating strategy can pave the way for developing high-performance LIBs.
基金supported by the Romanian Ministry of Education and Research within the Nucleu Programme(Project PN 09-44)
文摘ZnO nanoparticles（ZnO NPs） were synthesized by chemical method（coprecipitation） and biological method using aqueous extracts of garlic（Allium sativum）,rosemary（Rosmarinus officinalis） and basil（Ocimum basilicum）.The influence of plant extract on the antibacterial and antioxidant activities of green synthesized nanoparticles was investigated.The X-ray diffraction studies reveal that all ZnO samples have hexagonal wurtzite structure.The particle size of ZnO NPs estimated by transmission electron microscopy analysis（between 14 and 27 nm） varies depending on the synthesis method of nanoparticles and the type of extracts from the plants used.The functional groups involved in the biosynthetic procedure were evidenced by Fourier transform infrared spectroscopy.The presence of Mn^（2＋）ions,Zn vacancy complexes and oxygen vacancies in ZnO samples was highlighted by electron paramagnetic resonance spectroscopy.The green synthesized ZnO NPs have shown a good bactericidal activity against Staphylococcus aureus,Bacillus subtilis,Listeria monocytogenes,Escherichia coli,Salmonella typhimurium and Pseudomonas aeruginosa bacterial strains.ZnO NPs synthesized using extracts of the selected plant species have been found to exhibit more enhanced antibacterial and antioxidant activities as compared to chemical ZnO NPs.
基金supported by National Natural Science Foundation of China(Nos.11305218,11575253)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2015262)+1 种基金the CASHIPS Director’s Fund(No.YZJJ201505)Anhui Provincial Natural Science Foundation for Distinguished Young Scholars of China(No.1608085J03)
文摘It is reported that the highly dispersed Pt nanoparticles on carbon nanotubes can be synthesized under mild conditions by in situ plasma treatment.The carbon nanotube was pretreated by O_2 plasma to transform into oxide carbon nanotubes（O-CNTs）,and then it was mixed with the precursors（the mixture of H_2 PtCl_6and PdCl_6）.After that,the O-CNTs and the precursors were simultaneously treated by H_2 plasma.The precursors were transformed into Pt-Pd nanoparticles（NPs）and the O-CNTs transformed into CNT.The synthesized CNT-based Pt-Pd nanoparticles were characterized by scanning electron microscopy,transmission electron microscopy,X-ray diffraction and X-ray photoelectron spectroscopy.All the analysis showed that the Pt-Pd nanoparticles were deposited on CNT as a form of face-centered cubical structure.
基金UGC-BSR for providing meritorious research fellowship。
文摘Development of environmentally benign methods for synthesis of nanoparticles is an evolving important branch of nanotechnology.In the present study we report a green method for synthesis of stable silver nanoparticles(SNPs)from aqueous leaf extract of Syzygium alternifolium an endemic medicinal plant to Southern Eastern Ghats.These green synthesized nanoparticles are characterized by using UV-VIS spectroscopy,FTIR,XRD,AFM,SEM with EDAX and TEM.The colour change from yellow to grey is observed upon synthesis and 448 nm peak was obtained from UV-VIS spectroscopic analysis.FTIR spectroscopic studies confirms that phenols and proteins of leaf extract is main responsible for capping and stabilization of these SNPs.Crystallographic studies from XRD indicated the SNPs are crystalline in nature and owing 44 nm size.High resolution and magnification studies with AFM,SEM and TEM analysis revealed that the nanoparticles are spherical in shape having the size range from 7 to 44 nm.EDAX pattern of synthesized SNPs showed 47.28 weight percentage of Ag metal in the sample indicate the purity of sample.Further,the antimicrobial studies of these green synthesized SNPs show high toxicity towards different bacterial and fungal isolates.The results revealed that the selected medicinal plant possess the potentiality towards the synthesis of narrow range nanoparticles also combat with the pathogens.
基金by NSF/DMR 0606264 and a GAANN fellowship(Y.Lee).
文摘Monodisperse Au nanoparticles(NPs)have been synthesized at room temperature via a burst nucleation of Au upon injection of the reducing agent t-butylamine-borane complex into a 1,2,3,4-tetrahydronaphthalene solution of HAuCl4·3H2O in the presence of oleylamine.The as-synthesized Au NPs show size-dependent surface plasmonic properties between 520 and 530 nm.They adopt an icosahedral shape and are polycrystalline with multiple-twinned structures.When deposited on a graphitized porous carbon support,the NPs are highly active for CO oxidation,showing 100%CO conversion at-45°C.
