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Iron-oxidizing bacteria produce trivalent iron oxides with the controlled crystal phases outside of their cells. Herein we have synthesized iron oxides with controlled oxidation states and crystal phases through a microbial-mineralization-inspired approach in an aqueous solution at low temperature. Trivalent iron oxides, such as lepidocrocite, ferrihydrite, goethite, and hematite, are selectively obtained from an aqueous solution containing divalent iron ions below 90 °C. The presence of a chelating agent facilitates the control of the oxidation states through the ligand-controlled approach because the precipitation of the divalent iron species is inhibited by the complexation between divalent iron ion and a chelating agent. The control of the crystal phases is achieved by the tuning of the synthetic conditions, such as the initial pH, the concentration of a chelating agent, and the reaction temperature. Furthermore, the resultant iron oxides have hierarchically organized structures consisting of nanoscale objects. The microbial-mineralization-inspired approach by using a chelating agent has potentials for the further morphological control of iron oxides and the further application to aqueous-solution syntheses of other metal oxides. 相似文献
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Emanuel Carlos Prof. Rodrigo Martins Prof. Elvira Fortunato Prof. Rita Branquinho 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(42):9099-9125
Solution combustion synthesis (SCS) has been widely used to produce simple and complex oxides with a desired morphology (size and shape). SCS is valuable due to low cost, simplicity and energy efficient synthesis. To guarantee the best molecular-level mixing of reactants in an aqueous or solvent-based solution some parameters need to be controlled, such as fuel type, metal cations precursors, stoichiometry ratio (φ), pH effect, atmosphere and initiation type. These determine the final properties of the oxide materials, providing the potential to reach different morphologies, which are essential for their final applications. This Review article focuses on the crucial parameters in SCS and how these affect the overall materials properties from nanostructures to thin films. To finalize, special attention is given to the application of SCS to form metal oxide thin films at low temperature and their application in thin film transistors (TFTs). 相似文献
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Constructing complex nanostructures has become increasingly important in the development of hydrogen storage, self‐cleaning materials, and the formation of chiral branched nanowires. Several approaches have been developed to generate complex nanostructures, which have led to novel applications. Combining biology and nanotechnology through the utilization of biomolecules to chemically template the growth of complex nanostructures during synthesis has aroused great interest. Herein, we use a biomolecule‐assisted hydrothermal method to synthesize β‐phase Ni(OH)2 peony‐like complex nanostructures with second‐order structure nanoplate structure. The novel β‐Ni(OH)2 nanostructures exhibit high‐power Ni/MH battery performance, close to the theoretical capacity of Ni(OH)2, as well as controlled wetting behavior. We demonstrate that this bioinspired route to generate a complex nanostructure has applications in environmental protection and green secondary cells. This approach opens up opportunities for the synthesis and potential applications of new kinds of nanostructures. 相似文献
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Iron oxides, oxyhydroxydes and oxycarbonates derived from the layered Ruddlesden‐Popper (RP) structure form a large family of layered compounds. Besides the classical RP oxides Srn+1FenO3n+1, single intergrowths with the generic formulation (A,Sr)n+2FenO3n+2 and (A,Sr)n+3FenO3n+3 (A = Tl, Pb, Bi…) can be generated by increasing the multiplicity of the rock salt layers, and multiple intergrowths of these single intergrowths can be synthesized. Starting from oxygen deficient RP oxides such as n = 3 member Sr3NdFe3O9?δ, oxyhydroxydes hydrates and oxyhydroxydes such as Sr3NdFe3O7.5(OH)2·H2O and Sr3NdFe3O7.5(OH)2 can be created topotactically. Carbonate groups can also replace FeO6 octahedra in the n = 3 member Sr4Fe3O10, leading to layered oxycarbonates Sr4Fe3?x(CO3)xO10?4x with 0 < × ≤ 1. Shearing mechanism applied transversally to the layers allows collapsed structures to be generated such as the [Bi2Sr3Fe2O9]n [Bi4Sr6Fe2O16] family and the ferrite Bi13Ba2Sr25Fe13O66. Finally the replacement of rock salt SrO layers in the intergrowth Sr2FeO4 allows a new series of modulated structures [Sr8Fe12O26]·[Sr3Fe2O6]n to be generated, built up of layers of FeO5 bipyramids and tetragonal pyramids intergrown with perovskite layers. 相似文献
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Core–Shell Hollow Microspheres of Magnetic Iron Oxide@Amorphous Calcium Phosphate: Synthesis Using Adenosine 5′‐Triphosphate and Application in pH‐Responsive Drug Delivery
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Dr. Bing‐Qiang Lu Prof. Dr. Ying‐Jie Zhu Feng Chen Chao Qi Xin‐Yu Zhao Jing Zhao 《化学:亚洲杂志》2014,9(10):2908-2914
Drug nanocarriers with magnetic targeting and pH‐responsive drug‐release behavior are promising for applications in controlled drug delivery. Magnetic iron oxides show excellent magnetism, but their application in drug delivery is limited by low drug‐loading capacity and poor control over drug release. Herein, core–shell hollow microspheres of magnetic iron oxide@amorphous calcium phosphate (MIO@ACP) were prepared and investigated as magnetic, pH‐responsive drug nanocarriers. Hollow microspheres of magnetic iron oxide (HMIOs) were prepared by etching solid MIO microspheres in hydrochloric acid/ethanol solution. After loading a drug into the HMIOs, the drug‐loaded HMIOs were coated with a protective layer of ACP by using adenosine 5′‐triphosphate (ATP) disodium salt (Na2ATP) as stabilizer, and drug‐loaded core–shell hollow microspheres of MIO@ACP (HMIOs/drug/ACP) were obtained. The as‐prepared HMIOs/drug/ACP drug‐delivery system exhibits superparamagnetism and pH‐responsive drug‐release behavior. In a medium with pH 7.4, drug release was slow, but it was significantly accelerated at pH 4.5 due to dissolution of the ACP shell. Docetaxel‐loaded core–shell hollow microspheres of MIO@ACP exhibited high anticancer activity. 相似文献
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Waldemir Moura Carvalho Jr. Dr. Diogo Volpati Vitor A. Nunes Carvalho Prof. Ricardo F. Aroca Prof. Carlos J. L. Constantino Prof. Flavio L. Souza 《Chemphyschem》2013,14(9):1871-1876
One‐dimensional iron oxide materials fabricated on conducting glass substrates and their unique properties make these nanostructures promising candidates for a wide range of applications. Herein, vertically oriented α‐Fe2O3 nanorod arrays synthesized under hydrothermal conditions over a large area are described, as an active platform for surface‐enhanced resonance Raman scattering (SERRS) and surface‐enhanced fluorescence (SEF). From scanning electron microscopy images the formation of a homogeneous distribution of vertically oriented rods in a large area is confirmed. For activating the localized surface plasmon resonances, which are responsible for SERRS and SEF, a 6 nm layer of Ag is deposited onto the α‐Fe2O3 nanorod arrays by physical vapor deposition to form Ag islands. 相似文献
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Thin films of copper oxides can be synthesized on substrates by using approaches that are inspired by microbial mineralization processes. In nature, precipitates of manganese and iron oxides with controlled oxidation states and crystal phases are produced through biomineralization by microorganisms. We have previously reported microbial‐mineralization‐inspired approaches that are comprised of direct and intermediate routes for the controlled syntheses of transition‐metal oxides. Herein, these approaches are applied to the thin‐film formation and coating of copper oxides and a related compound with controlled crystal phases and morphologies. Thin films of CuO, Cu2O, and Cu2(OH)3Cl were selectively synthesized by using direct or intermediate routes. Notably, CuO mesocrystal nanosheets formed a thin film over the whole of the substrate. The resultant CuO mesocrystal nanosheets showed enhanced properties for the electrochemical detection of dopamine. This study shows the potential applicability of microbial‐mineralization‐inspired approaches to thin‐film coatings. 相似文献
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We demonstrate that the biomimetic method—which has been used for the formation of silica thin films—also could be applied directly to the formation of titanium dioxide (TiO2) thin films, which are technologically important materials because of their applications to photocatalytic purifiers, photochemical solar cells, and others. After generation of poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) films on gold surfaces by surface‐initiated polymerization, titanium bis(ammonium lactato)dihydroxide was used as a precursor of TiO2. The TiO2/PDMAEMA films were successfully formed on the surfaces in aqueous solution at neutral pH (pH 6.7) and room temperature, and were characterized by X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, and X‐ray diffractometry. The formed TiO2 films have an amorphous nature and large area uniformity in thickness. The degree of crystallization was controlled by annealing. We also investigated the pH effect and the phosphate incorporation in the films by using phosphate‐buffered solutions. The TiO2 films were formed in all the employed pH values in the range of 2 to 12, but phosphate anions were found to be incorporated into the films facilely only at low pH. 相似文献
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分别通过室温老化和高温沉降热处理成功的合成了大量均匀的Y-掺杂铈纳米颗粒和纳米棒,并对Y-掺杂铈粉末中Y的含量和形态对于固体溶液性质的影响进行了研究。结果表明,Y的掺杂大大提高了铈纳米颗粒和纳米棒的比表面积,其中30%的Y-掺杂纳米颗粒的比表面积最大,可达197 m2.g-1。此外,所制备的粉末可以很容易被烧结和硬化,而相应的电解质具有良好的电学性质,其中Y0.3Ce0.7O1.85纳米颗粒电解质在850℃时具有最大电导率(4.32 S.m-1)和最小表观活化能(0.81 eV)。 相似文献
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A large‐scale hierarchical assembly route is reported for the formation of SnO2 on the nanoscale that contains rigid and robust spheres with irregular channels for rapid access of Li ions into the hierarchically structured interiors. Large volume changes during the process of Li insertion and extraction are accommodated by the SnO2 nanoflake spheres’ internal porosity. The hierarchical SnO2 nanoflake spheres exhibit good lithium storage properties with high capacity and long‐lasting performance when used as lithium‐ion anodes. A reversible capacity of 517 mA h g?1, still greater than the theoretical capacity of graphite (372 mA h g?1), after 50 charge–discharge cycles is attained. Meanwhile, the synthesis process is simple, inexpensive, safe, and broadly applicable, providing new avenues for the rational engineering of electrode materials with enhanced conductivity and power. 相似文献
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Dr. Gousia Begum Joydeb Manna Dr. Rohit Kumar Rana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(22):6847-6853
In a bio‐inspired approach, polyamine‐mediated mineralization of ZnO was explored to develop an environmentally benign methodology for synthesizing Ag/AgCl/ZnO nanostructures. The assembling properties displayed by the polyamines to create composite structures was utilized to have the nanocomponents effectively interact with each other in a way that is desirable for the application envisaged. The polyamines, which act as a mineralizing agent for ZnO nanoparticles, also facilitate the formation of Ag/AgCl within ZnO under ambient conditions. Thus synthesized Ag/AgCl/ZnO nanostructures represent a multi‐heterojunction system in which the nanocomponents lead in a synergistic way to enhancement in the photocatalytic activity under visible‐light irradiation. 相似文献
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Dr. Panos Datskos Dr. David A. Cullen Dr. Jaswinder Sharma 《Angewandte Chemie (International ed. in English)》2015,54(31):9011-9015
The synthesis of complex and hybrid oxide microstructures is of fundamental interest and practical applications. However, the design and synthesis of such structures is a challenging task. A solution‐phase process to synthesize complex silica and silica–titania hybrid microstructures was developed by exploiting the emulsion‐droplet‐based step‐by‐step growth featuring shape control. The strategy is robust and can be extended to the preparation of complex hybrid structures consisting of two or more materials, with each having its own shape. 相似文献
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Dr. Xi Wang Yijun Yang Dr. Tianyou Zhai Yeteng Zhong Dr. Zhanjun Gu Prof. Y. Charles Cao Prof. Yuliang Zhao Dr. Ying Ma Prof. Jiannian Yao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(17):5442-5449
We have demonstrated a new and facile bottom‐up protocol for the effective synthesis of oval‐shaped iron oxide/ethylene glycol (FeOx/EG) mesostructured nanosheets. Deprotonated ethylene glycol molecules are intercalated into iron oxide layers to form an interlayer distance of 10.6 Å. These materials display some peculiar magnetic properties, such as the low Morin temperature TM and ferromagnetism below this TM value. CdSe/ZnS nanoparticles can be loaded onto these mesostructured nanosheets to produce nanocomposites that combine both magnetic and fluorescence functions. In addition, iron oxide/propanediol (or butanediol) mesostructured materials with increased interlayer distances can also be synthesized. The developed synthetic strategy may be extended toward the creation of other ultrathin mesostructured nanosheets. 相似文献
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Development of an Iron(II)‐Catalyzed Aerobic Catechol Cleavage and Biomimetic Synthesis of Betanidin
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Dr. Nicolas Guimond Dr. Peter Mayer Prof. Dr. Dirk Trauner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9519-9523
An aerobic iron(II)‐catalyzed cleavage of catechols was developed. This reaction allows for the preparation of 2‐methoxy‐2 H‐pyrans that can be employed as versatile building blocks for synthesis. The utility of this biomimetic oxidative cleavage is featured in the synthesis of betanidin, a natural colorant with antioxidant properties. 相似文献