General, Spontaneous Ion Replacement Reaction for the Synthesis of Micro- and Nanostructured Metal Oxides

A novel spontaneous ion replacement route based on the solubility difference as the driving force to synthesize a number of metal oxides has been established. We present a comprehensive study on the ion replacement reaction for chemical synthesis of micro- and nanostructured Mn2O3, ZnO, CuO, CdO, Al2O3, and CaO samples. This novel approach described herein is derived from the solubility difference between two carbonate salts, in which a metal cation can be driven from one liquid phase into another solid phase in the solution system. The resulting metal carbonate salts are initially formed and subsequently calcined to form highly crystallined metal oxides. The variation of pH values, reaction temperature, and reagent shapes can vary the solubility of these two carbonate salts, which thus changes the final morphology of metal oxides. The present work makes a progress to simply and mildly synthesize metal oxides with various morphologies, due to the fact that materials with a desired morphology are a key engineering step toward their shape-dependent chemical and physical properties

Room-Temperature Chemical Transformation Route to CuO Nanowires toward High-Performance Electrode Materials

We demonstrated an efficient room-temperature chemical transformation route to CuO nanowires (NWs), from irregular particles to NWs coupled with a series of phase changes from CuCl, through Cu2(OH)3Cl, to Cu­(OH)2, and finally to CuO. The room-temperature chemical transformation of Cu­(OH)2 NW can reserve the initial NW morphology and made the synthesized CuO NW more active in electrochemical reactions. As the anode materials for lithium ion battery, these CuO NWs can exhibit a reversible capacity of 696.1 mAh g–1 after 40 cycles at the rate of 100 mA g–1. The high lithium-storage capacity can be ascribed to the unique structure of these CuO NWs with size of ∼10 nm and grain boundaries on the NWs surfaces, which show more active for the initial electrochemical reaction. CuO NWs and intermediate Cu­(OH)2 NWs can also be fabricated as pseudocapacitor electrodes; in KOH electrolyte, their specific capacitances are 118 and 114 F g–1 at the current density of 1 A g–1. The present results indicate that the current room-temperature chemical transformation route is promising to produce advanced electrode materials for both lithium ion batteries and supercapacitors

Fabrication of Copper Hydroxyphosphate with Complex Architectures

Copper hydroxyphosphate [Cu2(OH)PO4] with complex architectures has been synthesized through a simple and mild hydrothermal route in the absence of any external inorganic additives or organic structure-directing templates. Powder X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectrometry are used to characterize various properties of the obtained samples. Single-crystals, twinned-crystals, and various novel architectures of copper hydroxyphosphate can be constructed through a careful control of synthetic parameters, such as the molar ratio of initial reagents, reagent concentration, reaction time, and temperature. On the basis of structure and chemical bond analysis, copper hydroxyphosphate crystals tend to grow along the c-axis and have a rotation twinned-crystal growth habit, which is essential for the formation of various complex architectures. The current approach provides a facile strategy to synthesize copper hydroxyphosphate crystals with unique morphologies and complex architectures, which may be applicable to the synthesis of other inorganic materials

3D Coordination Framework [Ln₄(μ₃-OH)₂Cu₆I₅(IN)₈(OAc)₃] (IN = Isonicotinate): Employing 2D Layers of Lanthanide Wheel Clusters and 1D Chains of Copper Halide Clusters

Two novel 3D heterometallic coordination polymers, Ln4(μ3-OH)2Cu6I5(IN)8(OAc)3 (Ln = Nd (1), Pr (2); HIN = isonicotinic acid, HOAc = acetic acid), have been synthesized under hydrothermal conditions and characterized by elemental, infrared, and thermogravimetric analyses and single-crystal X-ray diffraction. Both compounds are isostructural and crystallize in the monoclinic system, space group P21/c. Both polymers are constructed from 2D lanthanide-cluster polymers based on the {Ln16} wheel-cluster and 1D copper-cluster polymers based on the {Cu6I5} cluster, which represent the first examples of 3D coordination frameworks created by using a combination of two different types of metal-cluster polymer units, namely, a high-nuclearity lanthanide-cluster polymer and a transition-metal-cluster polymer

Incorporating Metal Clusters into Three-Dimensional Ln(III)−Cu(I) Coordination Frameworks through Linear Ligands

By using linear multifunctional ligands with different geometries, three novel three-dimensional (3D) Ln−M heterometallic coordination polymers, [Nd(H2O)2(CuI)2(nic)3]·H2O (1) (Hnic = nicotinic acid) and [LnCu(inic)2(ox)]·H2O [Ln = Nd (2), Eu (3); Hinic = isonicotinic acid, H2ox = oxalic acid], have been synthesized under hydrothermal conditions. Compound 1 exhibits a novel 3D coordination framework constructed by Cu4I4 clusters, Nd centers, and nic ligands. Our present work represents the first example of 3D Ln−M heterometallic coordination framework incorporating discrete cubane transition metal clusters covalently bonded to lanthanide centers through linear ligands. An unusual chemical rearrangement from Hinic to ox occurs in the formation of 2 and 3. Compounds 2 and 3 are isostructural and possess the first 3D coordination framework based on the linkage of two-dimensional layers constructed by tetranuclear Ln2Cu2 clusters and inic ligands. Furthermore, the luminescent properties of 3 were studied

A Modified Electroless Deposition Route to Dendritic Cu Metal Nanostructures

Metal Cu nanomaterials are highly desirable for being used in many applications and most widely used in electrical conductivity much more than silver and gold because of its low price and stability at high frequencies. In this paper, a modified electroless deposition strategy has been discovered for the first synthesis of novel Cu dendritic nanostructures. We have adopted the diffusion-limited growth and oriented attachment mechanism, which take effect equally during the nucleation and growth process, to account for the formation mechanism of the unique Cu dendritic nanostructures. The obtained Cu dendritic nanostructures can bring wide applications in optics, gas sensors, catalysts, information storage, and other related fields and sheds new insights to understand the formation process of fractal dendritic structures in the natural and synthetic world. Most importantly, the method reported in this work provides a new principle for the designing synthesis of dendritic metal nanomaterials and can be regarded as a general way to fabricate other nanomaterials

3D Coordination Framework [Ln₄(μ₃-OH)₂Cu₆I₅(IN)₈(OAc)₃] (IN = Isonicotinate): Employing 2D Layers of Lanthanide Wheel Clusters and 1D Chains of Copper Halide Clusters

Two novel 3D heterometallic coordination polymers, Ln4(μ3-OH)2Cu6I5(IN)8(OAc)3 (Ln = Nd (1), Pr (2); HIN = isonicotinic acid, HOAc = acetic acid), have been synthesized under hydrothermal conditions and characterized by elemental, infrared, and thermogravimetric analyses and single-crystal X-ray diffraction. Both compounds are isostructural and crystallize in the monoclinic system, space group P21/c. Both polymers are constructed from 2D lanthanide-cluster polymers based on the {Ln16} wheel-cluster and 1D copper-cluster polymers based on the {Cu6I5} cluster, which represent the first examples of 3D coordination frameworks created by using a combination of two different types of metal-cluster polymer units, namely, a high-nuclearity lanthanide-cluster polymer and a transition-metal-cluster polymer

Novel Self-Assembled MgO Nanosheet and Its Precursors

A novel self-assembled microstructure, nestlike Mg5(CO3)4(OH)2·4H2O spheres, is formed by a self-assembly of nanosheets in the hydrothermal process. MgO with the similar morphology can be obtained by calcination of nestlike Mg5(CO3)4(OH)2·4H2O. MgO precursors with a uniform, ellipsoid-shaped, and smooth surface or flowerlike architecture, built by individual thin sheets, can be well-obtained by carefully controlling pH values of the initial reaction solution. The nestlike MgO exhibits a unique geometrical shape; its surface is composed of uniform MgO nanosheets. The unique MgO microstructure with high surface areas may possess promising applications as the sorbent for chemisorption and destructive adsorption of various pollutants

Spontaneously Resolved Homochiral 3D Lanthanide−Silver Heterometallic Coordination Framework with Extended Helical Ln−O−Ag Subunits

Two novel homochiral lanthanide−silver heterometallic coordination polymers LnAg(OAc)(IN)3 [Ln = Nd (1), Eu (2), HIN = isonicotinic acid, HOAc = acetic acid] have been prepared under hydrothermal conditions, which were characterized by elemental analysis, infrared, thermogravimetric analysis, and single-crystal X-ray diffraction. Both complexes are isostructural and crystallize in a hexagonal system, chiral space group P6122. Both polymers are constructed from infinite right-handed homochiral helical chains with Ln−O−Ag connectivity, representing the first examples of homochiral lanthanide−transition metal heterometallic coordination polymers with a 3D coordination framework based on spontaneous resolution. Furthermore, the luminescent properties of 2 were studied

Selected Controlled Synthesis of Three-Dimensional 4d−4f Heterometallic Coordination Frameworks by Lanthanide Carboxylate Subunits and Silver Centers

By control of mixed ligands with particular coordination sites, three novel three-dimensional (3D) 4d−4f heterometallic coordination polymers, [Ln4(H2O)2Ag(1,3-bdc)4(inic)5]·nH2O (Ln = Nd (1), n = 0.25; Eu (2), n = 0; 1,3-H2bdc = 1,3-benzenedicarboxylic acid and Hinic = isonicotinic acid) and [Nd(H2O)Ag(1,2-bdc)(inic)2] (3) (1,2-H2bdc = 1,2-benzenedicarboxylic acid), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, thermogravimetric (TG) analysis, and single-crystal X-ray diffraction. Compounds 1−3 crystallize in the monoclinic system, space group C2/c. Compounds 1 and 2 are isostructural and exhibit novel 3D coordination frameworks constructed from two-dimensional (2D) wavelike lanthanide carboxylate layers and Ag(inic)4 complexes. To the best of our knowledge, they represent the first examples of 3D 4d−4f heterometallic coordination frameworks, in which the transition metal complexes bond to a 3D lanthanide carboxylate supramolecular framework with nanometer-sized channels built up from 2D wavelike layers. Compound 3 possesses an unusual 3D framework based on linkage of neodymium−carboxylate chains and silver(I) centers by inic ligands. The difference between both kinds of frameworks can be ascribed to the geometry effect of benzenedicarboxylate. Furthermore, the luminescent properties of 2 were studied