Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

The applications of copper (Cu) and Cu-based nanoparticles, which are based on the earth-abundant and inexpensive copper metal, have generated a great deal of interest in recent years, especially in the field of catalysis. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. In addition, the design and development of novel support and/or multimetallic systems (e.g., alloys, etc.) has also made significant contributions to the field. In this comprehensive review, we report different synthetic approaches to Cu and Cu-based nanoparticles (metallic copper, copper oxides, and hybrid copper nanostructures) and copper nanoparticles immobilized into or supported on various support materials (SiO2, magnetic support materials, etc.), along with their applications i...

http://pubs.acs.org/doi/pdfplus/10.1021/acs.chemrev.5b00482

Cu and Cu-Based Nanoparticles: Synthesis and Applications in Catalysis.

Nanotechnology is being used to enhance conventional ceramic and polymeric water treatment membrane materials through various avenues. Among the numerous concepts proposed, the most promising to date include zeolitic and catalytic nanoparticle coated ceramic membranes, hybrid inorganic–organic nanocomposite membranes, and bio-inspired membranes such as hybrid protein–polymer biomimetic membranes, aligned nanotube membranes, and isoporous block copolymer membranes. A semi-quantitative ranking system was proposed considering projected performance enhancement (over state-of-the-art analogs) and state of commercial readiness. Performance enhancement was based on water permeability, solute selectivity, and operational robustness, while commercial readiness was based on known or anticipated material costs, scalability (for large scale water treatment applications), and compatibility with existing manufacturing infrastructure. Overall, bio-inspired membranes are farthest from commercial reality, but offer the most promise for performance enhancements; however, nanocomposite membranes offering significant performance enhancements are already commercially available. Zeolitic and catalytic membranes appear reasonably far from commercial reality and offer small to moderate performance enhancements. The ranking of each membrane nanotechnology is discussed along with the key commercialization hurdles for each membrane nanotechnology.

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A review of water treatment membrane nanotechnologies

Metal oxide hollow structures have received great attention because of their many promising applications in a wide range of fields. As electrode materials for lithium-ion batteries (LIBs), metal oxide hollow structures provide high specific capacity, superior rate capability, and improved cycling performance. In this Research News, we summarize the recent research activities in the synthesis of metal oxide hollow nanostructures with controlled shape, size,composition, and structural complexity, as well as their applications in LIBs. By focusing on hollow structures of some binary metal oxides (such as SnO 2 ,TiO 2 , Fe 2 O 3 , Co 3 O 4 ) and complex metal oxides, we seek to provide some rational understanding on the effect of nanostructure engineering on the electrochemical performance of the active materials. It is thus anticipated that this article will shed some light on the development of advanced electrode materials for next-generation LIBs.

Metal oxide hollow nanostructures for lithium-ion batteries

This is the first targeted review of the synthesis – microstructure – electrochemical performance relations of MoS2 – based anodes and cathodes for secondary lithium ion batteries (LIBs). Molybdenum disulfide is a highly promising material for LIBs that compensates for its intermediate insertion voltage (∼2 V vs. Li/Li+) with a high reversible capacity (up to 1290 mA h g−1) and an excellent rate capability (e.g. 554 mA h g−1 after 20 cycles at 50 C). Several themes emerge when surveying the scientific literature on the subject: first, we argue that there is excellent data to show that truly nanoscale structures, which often contain a nanodispersed carbon phase, consistently possess superior charge storage capacity and cycling performance. We provide several hypotheses regarding why the measured capacities in such architectures are well above the theoretical predictions of the known MoS2 intercalation and conversion reactions. Second, we highlight the growing microstructural and electrochemical evidence that the layered MoS2 structure does not survive past the initial lithiation cycle, and that subsequently the electrochemically active material is actually elemental sulfur. Third, we show that certain synthesis techniques are consistently demonstrated to be the most promising for battery applications, and describe these in detail. Fourth, we present our selection of synthesis methods that we believe to have a high potential for creating improved MoS2 LIB electrodes, but are yet to be tried.

Lithium ion battery applications of molybdenum disulfide (MoS2) nanocomposites

Preparation and magnetic properties of magnetite nanoparticles by sol–gel method

An interesting shape evolution of Cu2O crystals, that is, from cubes, truncated octahedra, octahedra, and finally to nanospheres was first realized in high yield by reducing the copper−citrate complex solution with glucose. X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM) techniques were employed to characterize the samples. We elucidate the important parameters (including poly (vinyl pyrrolidone) (PVP) concentration, reaction time, and reaction temperature) responsible for the shape-controlled synthesis of Cu2O crystals. The possible formation mechanism for the products with various architectures is presented, which is mainly based on the variation of the ratio (R) of the growth rates along the ⟨100⟩ and ⟨111⟩ direction. In addition, the effect of the low supersaturation on the formation of star-shaped samples with six symmetric branches is also taken into account. This polymer-mediated method should be readi...

Low Temperature Synthesis of Cu2O Crystals: Shape Evolution and Growth Mechanism

In recent years, hollow-structure particles (HSPs) have been widely studied due to their unique structures and potential applications. One successful synthetic strategy involves direct construction of HSPs from functional building blocks by processes such as the Kirkendall effect, acid etching, coordination-polymer self-template-directed growth, and solid-state thermal decomposition process for the preparation of Cu7S4, [2] Fe2O3, [3] ZnO, and MnO2 [5] HSPs. However, all of the reported HSPs require further heator acid-treatment processes, which have disadvantages such as increased costs and environmental pollution. Therefore, it remains a great challenge to develop a simple, mild (at room temperature), and environmentally friendly method for the one-pot synthesis of HSPs with well-defined shape. Cu2O is a typical p-type direct band gap semiconductor with a band gap of 2.17 eV and has potential applications in solar-energy conversion, electrode materials, sensors, and catalysts. Considerable effort has been devoted to obtaining hollow Cu2O structure by employing techniques such as hydrothermal synthesis, microemulsions, template synthesis, and acid etching. Qi and co-workers prepared octahedral Cu2O nanocages by Pd-catalytic reduction of an alkaline copper tartrate complex with glucose followed by a catalytic oxidation process. More recently, truncated rhombic dodecahedral Cu2O nanoframes and nanocages were synthesized by particle aggregation and acid etching. In both synthetic processes, expensive and acidic or toxic solvents were used. Here we report a cheap and green synthetic route for Cu2O nanoframes and nanocages with single-crystal walls. In our synthetic strategy, polyhedral Cu2O particles were first prepared by adding a weak reducing agent (glucose) to a solution of copper citrate complex with polyvinylpyrrolidone (PVP) as capping agent, and then Cu2O nanoframes and nanocages were obtained in situ by oxidative etching at room temperature. Perfect Cu2O nanoframes were taken from the reaction mixture after the solution was exposed to air for 16 days at room temperature. Field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM) images provided insight into the nanostructure and morphology of the Cu2O nanoframes. As shown in Figure 1A, the Cu2O nanoframes are

Synthesis of Cu2O Nanoframes and Nanocages by Selective Oxidative Etching at Room Temperature

Synthesis and characterization of TiO2 nanotubes for humidity sensing

Well-defined cuprous oxide (Cu2O) thin film electrodes were electrodeposited on indium-doped tin oxide (ITO) substrates from a slightly acidic Cu(II) acetate solution The morphologies of Cu2O film were tunable by altering the deposition potential, reaction time, solution temperature and the NaCl concentration In particular, the Cu2O morphologies evolved from dendritic branching to cube-like with the increasing of the NaCl concentration A growth mechanism was proposed according to the experimental results In addition, a photocurrent of 006 mA cm−2, an open-circuit photovoltage (Voc) of 038 V, and a significant energy conversation efficiency of 001% were obtained under 100 mW cm−2 UV-visible illumination of the dendritic Cu2O thin film

Wuyou Fu

Papers

Preparation and magnetic properties of magnetite nanoparticles by sol–gel method

Low Temperature Synthesis of Cu2O Crystals: Shape Evolution and Growth Mechanism

Synthesis of Cu2O Nanoframes and Nanocages by Selective Oxidative Etching at Room Temperature

Synthesis and characterization of TiO2 nanotubes for humidity sensing

Electrodeposition of Cu2O films and their photoelectrochemical properties