The effect of additive RCOONa on the formation of MnZn ferrite homogeneous coprecipitation precursor was studied in this paper. The action of additive in the MnZn ferrite hydrothermal crystallization process was inves...The effect of additive RCOONa on the formation of MnZn ferrite homogeneous coprecipitation precursor was studied in this paper. The action of additive in the MnZn ferrite hydrothermal crystallization process was investigated according to crystal field theory and crystal growth unit theory. And the growth unit formation process was presented and its structure was illustrated. The results show that the precursor of MnZn ferrite is a colloidal mixture composed of Zn(OH) 2, Fe(OH) 2, Mn(OH) 2, MnO(OH) , MnO 2· x H 2O and so on, and dissolves in solution in the form of hydroxyl coordination tetrahedron and octahedron such as Zn(OH) 2- 4, Fe(OH) 2- 4, Fe(OH) 4- 6,Fe(OH) - 4, Fe(OH) 3- 6,Mn(OH) 2- 4,Mn(OH) 3- 6 etc., and the growth unit is formed by combination of the coordination polyhedra subsequently in the hydrothermal precess. The additive is beneficial to the formation of homogeneous precursor and has dispersive effect on the aggregation of the crystal growth unit by forming associate with hydrogen bond, which is beneficial to the synthesis of the pure product with a tiny size and a narrow size distribution.展开更多
Ferroplasma thermophilum,a sort of extreme acidophilic archaea,which can synthesize intracellular cobalt ferrite nanocrystals,is investigated in this study.The nanocrystals were analyzed with ultrathin sections and tr...Ferroplasma thermophilum,a sort of extreme acidophilic archaea,which can synthesize intracellular cobalt ferrite nanocrystals,is investigated in this study.The nanocrystals were analyzed with ultrathin sections and transmission electron microscope,with the size of 20−60 nm,the number of more than 30 in each cell at average,which indicated that F.thermophilum can synthesize intracellular nanocrystals and also belongs to high-yield nanocrystals-producing strain.Intriguingly,the nanocrystals contain ferrite and cobalt characterized by EDS X-ray analysis,suggesting that both cobalt and ferrite are potentially contributed to the formation of nanocrystals.Moreover,under the different energy source culture conditions of FeSO4 and CuFeS2,the size and the morphology of the nanocrystals are different.It was also found that the higher initial Fe availability leads to an induced synthesis of larger nanocrystals and the lower oxidation-reduction potential(ORP)leads to an induced effect on the synthesis of nanocrystals with abnormal unhomogeneous size,which suggested that the higher initial Fe availability and the lower oxidation-reduction potential lead to a higher uptake efficiency of iron ions of F.thermophilum by iron and ORP gradient culture.展开更多
Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which oct...Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which octadecene was used as solvent, and oleic acid and oleylamine were used as capping ligands. MnFe204 nanocrystals were obtained with size in a tunable range of 4- 15 nm and their morphologies could be tuned from spherical to triangle-shaped by varying the surfactants. The phase structure, morphology, and size of the products were characterized in detail by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. Magnetic properties of MnFe2O4 nanocrystals with different morphologies were measured using a superconducting quantum interference device （SQUID）. Both monodisperse MnFe204 nanocrystals with spherical and triangle-shapes are superparamagnetic at room temperature while ferromagnetic at 2 K. The pyrolysis method may provide an effective route to synthesize other spinel ferrites or metal oxides nanocrystals.展开更多
The rational design of complex nanostructures is of paramount importance to gain control over their chemical and physical properties.Recently,magnetic-plasmonic heterostructured nanocrystals have been recognized as ke...The rational design of complex nanostructures is of paramount importance to gain control over their chemical and physical properties.Recently,magnetic-plasmonic heterostructured nanocrystals have been recognized as key players in nanomedicine as multifunctional therapeutic-diagnostic tools and in catalysis.Here we show how the properties of gold-iron oxide heterostructured nanocrystals can be tuned by chemical doping of the magnetic subunit.The divalent cations in the iron oxide were substituted with cobalt and manganese to obtain a general formula Au-MFe2O4(M=Fe,Co,Mn).Magnetic properties of the heterostructures could be tuned,while maintaining well-defined plasmon resonance signatures,confirming the dual magnetic-plasmonic functional capability of these nanostructures.展开更多
BiFeO_(3)(BFO)是一种新型可回收光响应催化剂,但较高的光生电子/空穴对复合率和较低的量子产率限制了其实际应用。本研究通过水热法制备出还原氧化石墨烯-BFO(RGO-BFO)纳米晶复合材料,表征与测试结果表明,相比于BFO颗粒,复合材料的禁...BiFeO_(3)(BFO)是一种新型可回收光响应催化剂,但较高的光生电子/空穴对复合率和较低的量子产率限制了其实际应用。本研究通过水热法制备出还原氧化石墨烯-BFO(RGO-BFO)纳米晶复合材料,表征与测试结果表明,相比于BFO颗粒,复合材料的禁带宽度E_(g)为2.0 e V,降低约10%;40 min对亚甲基蓝吸附–催化效率接近100%,远高于BFO颗粒(28%),这主要由于复合体系中光生电子/空穴对复合率更低。通过本征磁性回收并重复利用6次后,复合材料仍保持89.1%催化效率,表现出优异催化性能。展开更多
To improve the visible light absorption and photocatalytic activity of titanium dioxide nanotube arrays(TONTAs), ZnFe_2O_4(ZFO) nanocrystals were perfused into pristine TONTA pipelines using a novel bias voltageassist...To improve the visible light absorption and photocatalytic activity of titanium dioxide nanotube arrays(TONTAs), ZnFe_2O_4(ZFO) nanocrystals were perfused into pristine TONTA pipelines using a novel bias voltageassisted perfusion method. ZFO nanocrystals were well anchored on the inner walls of the pristine TONTAs when the ZFO suspensions(0.025 mg m L^(-1)) were kept under a60 V bias voltage for 1 h. After annealing at 750 °C for2 h, the heterostructured ZFO/Fe_2 TiO_5(FTO)/TiO_2 composite nanotube arrays were successfully obtained. Furthermore, Fe^(3+)was reduced to Fe^(2+)when solid solution reactions occurred at the interface of ZFO and the pristine TONTAs. Introducing ZFO significantly enhanced thevisible light absorption of the ZFO/FTO/TONTAs relative to that of the annealed TONTAs. The coexistence of type I and staggered type II band alignment in the ZFO/FTO/TONTAs facilitated the separation of photogenerated electrons and holes, thereby improving the efficiency of the ZFO/FTO/TONTAs for photocatalytic degradation of methylene blue when irradiated with simulated sunlight.展开更多
文摘The effect of additive RCOONa on the formation of MnZn ferrite homogeneous coprecipitation precursor was studied in this paper. The action of additive in the MnZn ferrite hydrothermal crystallization process was investigated according to crystal field theory and crystal growth unit theory. And the growth unit formation process was presented and its structure was illustrated. The results show that the precursor of MnZn ferrite is a colloidal mixture composed of Zn(OH) 2, Fe(OH) 2, Mn(OH) 2, MnO(OH) , MnO 2· x H 2O and so on, and dissolves in solution in the form of hydroxyl coordination tetrahedron and octahedron such as Zn(OH) 2- 4, Fe(OH) 2- 4, Fe(OH) 4- 6,Fe(OH) - 4, Fe(OH) 3- 6,Mn(OH) 2- 4,Mn(OH) 3- 6 etc., and the growth unit is formed by combination of the coordination polyhedra subsequently in the hydrothermal precess. The additive is beneficial to the formation of homogeneous precursor and has dispersive effect on the aggregation of the crystal growth unit by forming associate with hydrogen bond, which is beneficial to the synthesis of the pure product with a tiny size and a narrow size distribution.
基金Project(2018JJ1041)supported by the Natural Science Foundation of Hunan,ChinaProjects(51774332,51934009,U1932129)supported by the National Natural Science Foundation of China。
文摘Ferroplasma thermophilum,a sort of extreme acidophilic archaea,which can synthesize intracellular cobalt ferrite nanocrystals,is investigated in this study.The nanocrystals were analyzed with ultrathin sections and transmission electron microscope,with the size of 20−60 nm,the number of more than 30 in each cell at average,which indicated that F.thermophilum can synthesize intracellular nanocrystals and also belongs to high-yield nanocrystals-producing strain.Intriguingly,the nanocrystals contain ferrite and cobalt characterized by EDS X-ray analysis,suggesting that both cobalt and ferrite are potentially contributed to the formation of nanocrystals.Moreover,under the different energy source culture conditions of FeSO4 and CuFeS2,the size and the morphology of the nanocrystals are different.It was also found that the higher initial Fe availability leads to an induced synthesis of larger nanocrystals and the lower oxidation-reduction potential(ORP)leads to an induced effect on the synthesis of nanocrystals with abnormal unhomogeneous size,which suggested that the higher initial Fe availability and the lower oxidation-reduction potential lead to a higher uptake efficiency of iron ions of F.thermophilum by iron and ORP gradient culture.
基金Project(2010QZZD008) supported by the Prospect Key Projects of Fundamental Research Funds for the Central UniversitiesProject(2007FJ3008) supported by the Hunan Provincial Key Science and Technology Program of China
文摘Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which octadecene was used as solvent, and oleic acid and oleylamine were used as capping ligands. MnFe204 nanocrystals were obtained with size in a tunable range of 4- 15 nm and their morphologies could be tuned from spherical to triangle-shaped by varying the surfactants. The phase structure, morphology, and size of the products were characterized in detail by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. Magnetic properties of MnFe2O4 nanocrystals with different morphologies were measured using a superconducting quantum interference device （SQUID）. Both monodisperse MnFe204 nanocrystals with spherical and triangle-shapes are superparamagnetic at room temperature while ferromagnetic at 2 K. The pyrolysis method may provide an effective route to synthesize other spinel ferrites or metal oxides nanocrystals.
基金The financial support of European Union's Horizon2020 Research and Innovation program under Grant agreements No.737093 and No.720853
文摘The rational design of complex nanostructures is of paramount importance to gain control over their chemical and physical properties.Recently,magnetic-plasmonic heterostructured nanocrystals have been recognized as key players in nanomedicine as multifunctional therapeutic-diagnostic tools and in catalysis.Here we show how the properties of gold-iron oxide heterostructured nanocrystals can be tuned by chemical doping of the magnetic subunit.The divalent cations in the iron oxide were substituted with cobalt and manganese to obtain a general formula Au-MFe2O4(M=Fe,Co,Mn).Magnetic properties of the heterostructures could be tuned,while maintaining well-defined plasmon resonance signatures,confirming the dual magnetic-plasmonic functional capability of these nanostructures.
文摘BiFeO_(3)(BFO)是一种新型可回收光响应催化剂,但较高的光生电子/空穴对复合率和较低的量子产率限制了其实际应用。本研究通过水热法制备出还原氧化石墨烯-BFO(RGO-BFO)纳米晶复合材料,表征与测试结果表明,相比于BFO颗粒,复合材料的禁带宽度E_(g)为2.0 e V,降低约10%;40 min对亚甲基蓝吸附–催化效率接近100%,远高于BFO颗粒(28%),这主要由于复合体系中光生电子/空穴对复合率更低。通过本征磁性回收并重复利用6次后,复合材料仍保持89.1%催化效率,表现出优异催化性能。
基金financially supported by National Nature Science Foundation of China(Grant No.51402247 and 41630646)Sichuan Province Education Department Innovation Team Foundation(16zd1104)+2 种基金Sichuan Province Science Foundation for Young Scientists(No.15zs2111)Open Project of State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials(No.13zxfk11)Doctoral Research Foundation of Southwest University of Science and Technology(No.14zx7119)
文摘To improve the visible light absorption and photocatalytic activity of titanium dioxide nanotube arrays(TONTAs), ZnFe_2O_4(ZFO) nanocrystals were perfused into pristine TONTA pipelines using a novel bias voltageassisted perfusion method. ZFO nanocrystals were well anchored on the inner walls of the pristine TONTAs when the ZFO suspensions(0.025 mg m L^(-1)) were kept under a60 V bias voltage for 1 h. After annealing at 750 °C for2 h, the heterostructured ZFO/Fe_2 TiO_5(FTO)/TiO_2 composite nanotube arrays were successfully obtained. Furthermore, Fe^(3+)was reduced to Fe^(2+)when solid solution reactions occurred at the interface of ZFO and the pristine TONTAs. Introducing ZFO significantly enhanced thevisible light absorption of the ZFO/FTO/TONTAs relative to that of the annealed TONTAs. The coexistence of type I and staggered type II band alignment in the ZFO/FTO/TONTAs facilitated the separation of photogenerated electrons and holes, thereby improving the efficiency of the ZFO/FTO/TONTAs for photocatalytic degradation of methylene blue when irradiated with simulated sunlight.
