Precursor Polymers for the Carbon Coating of Au@ZnO Multipods for Application as Active Material in Lithium-Ion Batteries

Polymer Coated Semiconducting Nanoparticles for Hybrid Materials

This paper reviews synthetic concepts for the functionalization of various inorganic nanoparticles with a shell consisting of organic polymers and possible applications of the resulting hybrid materials. A polymer coating can make inorganic nanoparticles soluble in many solvents as individual particles and not only do low molar mass solvents become suitable, but also polymers as a solid matrix. In the case of shape anisotropic particles (e.g., rods) a spontaneous self-organization (parallel orientation) of the nanoparticles can be achieved, because of the formation of lyotropic liquid crystalline phases. They offer the possibility to orient the shape of anisotropic nanoparticles macroscopically in external electric fields. At least, such hybrid materials allow semiconducting inorganic nanoparticles to be dispersed in functional polymer matrices, like films of semiconducting polymers. Thereby, the inorganic nanoparticles can be electrically connected and addressed by the polymer matrix. This allows LEDs to be prepared with highly fluorescent inorganic nanoparticles (quantum dots) as chromophores. Recent works have aimed to further improve these fascinating light emitting materials.

Facile Sonochemical Preparation of Au-ZrO2 Nanocatalyst for the Catalytic Reduction of 4-Nitrophenol

High-intensity ultrasonic waves have great potential for the green synthesis of various nanomaterials under mild conditions and offer an excellent alternative for hazardous chemical methods. Herein a facile approach for the eco-friendly synthesis of Au-ZrO2 nanocatalyst with a high catalytic activity using a facile ultrasonic method is presented. Gold (Au) in the nanosize regime was successfully deposited on the surface of solvothermally synthesized monodispersed ZrO2 nanoparticles (ZrO2 NPs) in a very short period of time (5 min) at room temperature. Spherical shape small size Au nanoparticles that are uniformly dispersed on the surface of ZrO2 nanoparticles were obtained. Notably, in the absence of ZrO2 nanoparticles, HAuCl4 could not be reduced, indicating that nano-sized ZrO2 not only acted as support but also helped to reduce the gold precursor at the surface. The as-prepared Au-ZrO2 nanocatalyst was characterized by various techniques. The Au-ZrO2 nanocatalyst served as a highly efficient reducing catalyst for the reduction of 4-nitrophenol. The reaction time decreased with increasing the amount of catalyst.

Facile in situ growth of ZnO nanosheets standing on Ni foam as binder-free anodes for lithium ion batteries

ZnO has attracted increasing attention as an anode for lithium ion batteries. However, the application of such anode materials remains restricted by their poor conductivity and large volume changes during the charge/discharge process. Herein, we report a simple hydrothermal method to synthesize ZnO nanosheets with a large surface area standing on a Ni foam framework, which is applied as a binder-free anode for lithium ion batteries. ZnO nanosheets were grown in situ on Ni foam, resulting in enhanced conductivity and enough space to buffer the volume changes of the battery. The ZnO nanosheets@Ni foam anode showed a high specific capacity (1507 mA h g-1 at 0.2 A g-1), good capacity retention (1292 mA h g-1 after 45 cycles), and superior rate capacity, which are better than those of ZnO nanomaterial-based anodes reported previously. Moreover, other transition metal oxides, such as Fe2O3 and NiO were also formed in situ on Ni foam with perfect standing nanosheets structures by this hydrothermal method, confirming the universality and efficiency of this synthetic route.

Preparation of ZnO Nanorods/Graphene Composite Anodes for High-Performance Lithium-Ion Batteries

ZnO is a promising anode material for lithium-ion batteries (LIBs); however, its practical application is hindered primarily by its large volume variation upon lithiation. To overcome this drawback, we synthesized ZnO/graphene composites using the combination of a simple hydrothermal reaction and spray drying. These composites consisted of well-dispersed ZnO nanorods anchored to graphene. The folded three-dimensional graphene spheres provided a high conductivity, high surface area, and abundant defects. LIB with an anode composed of our novel ZnO/graphene material demonstrated a high initial discharge capacity of 1583 mAh g⁻¹ at 200 mA g⁻¹.

Block copolymers from ionic liquids for the preparation of thin carbonaceous shells

This paper describes the controlled radical polymerization of an ionic-liquid monomer by RAFT polymerization. This allows the control over the molecular weight of ionic liquid blocks in the range of 8000 and 22000 and of the block-copolymer synthesis. In this work we focus on block copolymers with an anchor block. They can be used to control the formation of TiO₂ nanoparticles, which are functionalized thereafter with a block of ionic-liquid polymer. Pyrolysis of these polymer functionalized inorganic nanoparticles leads to TiO₂ nanoparticles coated with a thin carbonaceous shell. Such materials may, e.g., be interesting as battery materials.

Synthesis of well-dispersed ZnO–Co–C composite hollow microspheres as advanced anode materials for lithium ion batteries

Well-dispersed ZnO–Co–C composite hollow microspheres exhibit excellent electrochemical properties when used as anode materials for lithium ion batteries.

A polyacrylonitrile copolymer-silica template for three-dimensional hierarchical porous carbon as a Pt catalyst support for the oxygen reduction reaction

Herein, we report a novel route to construct a hierarchical three-dimensional porous carbon (3DC) through a copolymer-silica assembly.

High performance of electrochemical lithium storage batteries: ZnO-based nanomaterials for lithium-ion and lithium-sulfur batteries

As one of the most promising electrode materials, zinc oxide-based nanomaterials have attracted great attention in recent decades for remarkable features such as relatively low cost, relatively high reversible capacity and good physical and chemical stability. In this article, we aim to present a general review of synthetic methods of zinc oxide-based nanomaterials and related morphologies. In addition, recent advances in lithium storage batteries are summarized and discussed (lithium-ion and lithium-sulfur batteries). Tentative conclusions and assessments aim to promote the next generation of electrochemical lithium storage devices.

Hierachical Ni@Fe2O3 superparticles through epitaxial growth of γ-Fe2O3 nanorods on in situ formed Ni nanoplates

One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Ni@γ-Fe2O3 superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3 (maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3 interface in combination with Mössbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 interface. The common orientation of the maghemite nanorods on the Ni core of the superparticles leads to a greatly enhanced magnetization. After functionalization with a catechol-functional polyethylene glycol (C-PEG) ligand the Ni@γ-Fe2O3 superparticles were dispersible in water.

Extraordinary Performance of Carbon-Coated Anatase TiO2 as Sodium-Ion Anode

The synthesis of in situ polymer-functionalized anatase TiO₂ particles using an anchoring block copolymer with hydroxamate as coordinating species is reported, which yields nanoparticles (≈11 nm) in multigram scale. Thermal annealing converts the polymer brushes into a uniform and homogeneous carbon coating as proven by high resolution transmission electron microscopy and Raman spectroscopy. The strong impact of particle size as well as carbon coating on the electrochemical performance of anatase TiO₂ is demonstrated. Downsizing the particles leads to higher reversible uptake/release of sodium cations per formula unit TiO₂ (e.g., 0.72 eq. Na⁺ (11 nm) vs only 0.56 eq. Na⁺ (40 nm)) while the carbon coating improves rate performance. The combination of small particle size and homogeneous carbon coating allows for the excellent electrochemical performance of anatase TiO₂ at high (134 mAh g^-1 at 10 C (3.35 A g^-1)) and low (≈227 mAh g^-1 at 0.1 C) current rates, high cycling stability (full capacity retention between 2nd and 300th cycle at 1 C) and improved coulombic efficiency (≈99.8%).

Morphology control in biphasic hybrid systems of semiconducting materials

Simple blends of inorganic nanocrystals and organic (semiconducting) polymers usually lead to macroscopic segregation. Thus, such blends typically exhibit inferior properties than expected. To overcome the problem of segregation, polymer coated nanocrystals (nanocomposites) have been developed. Such nanocomposites are highly miscible within the polymer matrix. In this Review, a summary of synthetic approaches to achieve stable nanocomposites in a semiconducting polymer matrix is presented. Furthermore, a theoretical background as well as an overview concerning morphology control of inorganic NCs in polymer matrices are provided. In addition, the morphologic behavior of highly anisotropic nanoparticles (i.e. liquid crystalline phase formation of nanorod-composites) and branched nanoparticles (spatial orientation of tetrapods) is described. Finally, the morphology requirements for the application of inorganic/organic hybrid systems in light emitting diodes and solar cells are discussed, and potential solutions to achieve the required morphologies are provided.