Large-Scale Synthesis of Necklace-Like Single-Crystalline PbTiO3 Nanowires

Electrospun nanofibers: promising nanomaterials for biomedical applications

With the rapid development of nanotechnology and nanomaterials science, electrospun nanofibers emerged as a new material with great potential for a variety of applications. Electrospinning is a simple and adaptable process for generation of nanofibers from a viscoelastic fluid using electrostatic repulsion between surface charges. Electrospinning has been used to manufacture nanofibers with low diameters from a wide range of materials. Electrospinning may also be used to construct nanofibers with a variety of secondary structures, including those having a porous, hollow, or core–sheath structure. Due to many attributes including their large specific surface area and high porosity, electrospun nanofibers are suitable for biosensing and environmental monitoring. This book chapter discusses the different methods of nanofiber preparations and the challenges involved, recent research progress in electrospun nanofibers, and the ways to commercialize these nanofiber materials.

Necklace-Like Nanostructures: From Fabrication, Properties to Applications

The shape-controlled synthesis of nanocrystals remains a hot research topic in nanotechnology. Particularly, the fabrication of 1D structures such as wires, rods, belts, and tubes has been an interesting and important subject within nanoscience in the last few decades. 1D necklace-like micro/nanostructures are a sophisticated geometry that has attracted increasing attention due to their anisotropic and periodic structure, intrinsic high surface area, abundant transport channels, exposure of each component to the surface, and multiscale roughness of the surface. These characteristics enable their unique electrical, optical, and catalytic properties. This review provides a comprehensive summary of the advanced research progress on the fabrication strategies, novel properties, and various applications of necklace-like structures. It begins with the main fabrication methods of necklace-like structures and subsequently details a variety of their properties and applications. It concludes with the authors' perspectives on future research and development of the necklace-like structures.

Electrospun CNF Supported Ceramics as Electrochemical Catalysts for Water Splitting and Fuel Cell: A Review

With the per capita growth of energy demand, there is a significant need for alternative and sustainable energy resources. Efficient electrochemical catalysis will play an important role in sustaining that need, and nanomaterials will play a crucial role, owing to their high surface area to volume ratio. Electrospun nanofiber is one of the most promising alternatives for producing such nanostructures. A section of key nano-electrocatalysts comprise of transition metals (TMs) and their derivatives, like oxides, sulfides, phosphides and carbides, etc., as well as their 1D composites with carbonaceous elements, like carbon nanotubes (CNTs) and carbon nanofiber (CNF), to utilize the fruits of TMs’ electronic structure, their inherent catalytic capability and the carbon counterparts’ stability, and electrical conductivity. In this work, we will discuss about such TM derivatives, mostly TM-based ceramics, grown on the CNF substrates via electrospinning. We will discuss about manufacturing methods, and their electrochemical catalysis performances in regards to energy conversion processes, dealing mostly with water splitting, the metal–air battery fuel cell, etc. This review will help to understand the recent evolution, challenges and future scopes related to electrospun transition metal derivative-based CNFs as electrocatalysts.

One-Dimensional Ferroelectric Nanostructures: Synthesis, Properties, and Applications

One-dimensional (1D) ferroelectric nanostructures, such as nanowires, nanorods, nanotubes, nanobelts, and nanofibers, have been studied with increasing intensity in recent years. Because of their excellent ferroelectric, ferroelastic, pyroelectric, piezoelectric, inverse piezoelectric, ferroelectric-photovoltaic (FE-PV), and other unique physical properties, 1D ferroelectric nanostructures have been widely used in energy-harvesting devices, nonvolatile random access memory applications, nanoelectromechanical systems, advanced sensors, FE-PV devices, and photocatalysis mechanisms. This review summarizes the current state of 1D ferroelectric nanostructures and provides an overview of the synthesis methods, properties, and practical applications of 1D nanostructures. Finally, the prospects for future investigations are outlined.

A general route to nanocrystal kebabs periodically assembled on stretched flexible polymer shish

Assembling nanoparticles into one-dimensional (1D) nanostructures with precisely controlled size and shape renders the exploration of new properties and construction of 1D miniaturized devices possible. The physical properties of such nanostructures depend heavily on the size, chemical composition, and surface chemistry of nanoparticle constituents, as well as the close proximity of adjacent nanoparticles within the 1D nanostructure. Chemical synthesis provides an intriguing alternative means of creating 1D nanostructures composed of self-assembled nanoparticles in terms of material diversity, size controllability, shape regularity, and low-cost production. However, this is an area where progress has been slower. We report an unconventional yet general strategy to craft an exciting variety of 1D nanonecklace-like nanostructures comprising uniform functional nanodiscs periodically assembled along a stretched flexible polymer chain by capitalizing on judiciously designed amphiphilic worm-like diblock copolymers as nanoreactors. These nanostructures can be regarded as organic-inorganic shish-kebabs, in which nanodisc kebabs are periodically situated on a stretched polymer shish. Simulations based on self-consistent field theory reveal that the formation of organic-inorganic shish-kebabs is guided by the self-assembled elongated star-like diblock copolymer constituents constrained on the highly stretched polymer chain.

Perovskite ferroelectric nanomaterials

In this review, the main concept of ferroelectricity of perovskite oxides and related materials at nanometer scale and existing difficulties in the synthesis of those nanocrystals are discussed. Important effects, such as depolarization field and size effect, on the existence of ferroelectricity in perovskite nanocrystals are deliberated. In the discussion of modeling works, different theoretical calculations are pinpointed focusing on their studies of lattice dynamics, phase transitions, new origin of ferroelectricity in nanostructures, etc. As the major part of this review, recent research progress in the facile synthesis, characterization and various applications of perovskite ferroelectric nanomaterials, such as BaTiO₃, PbTiO₃, PbZrO₃, and BiFeO₃, are also scrutinized. Perspectives concerning the future direction of ferroelectric nanomaterials research and its potential applications in renewable energy, etc., are presented. This review provides an overview in this area and guidance for further studies in perovskite ferroelectric nanomaterials and their applications.

Electro-spinning/netting: A strategy for the fabrication of three-dimensional polymer nano-fiber/nets

Since 2006, a rapid development has been achieved in a subject area, so called electro-spinning/netting (ESN), which comprises the conventional electrospinning process and a unique electro-netting process. Electro-netting overcomes the bottleneck problem of electrospinning technique and provides a versatile method for generating spider-web-like nano-nets with ultrafine fiber diameter less than 20 nm. Nano-nets, supported by the conventional electrospun nanofibers in the nano-fiber/nets (NFN) membranes, exhibit numerious attractive characteristics such as extremely small diameter, high porosity, and Steiner tree network geometry, which make NFN membranes optimal candidates for many significant applications. The progress made during the last few years in the field of ESN is highlighted in this review, with particular emphasis on results obtained in the author's research units. After a brief description of the development of the electrospinning and ESN techniques, several fundamental properties of NFN nanomaterials are addressed. Subsequently, the used polymers and the state-of-the-art strategies for the controllable fabrication of NFN membranes are highlighted in terms of the ESN process. Additionally, we highlight some potential applications associated with the remarkable features of NFN nanostructure. Our discussion is concluded with some personal perspectives on the future development in which this wonderful technique could be pursued.

One-dimensional nanostructures of ferroelectric perovskites

Nanorods, nanowires, and nanotubes of ferroelectric perovskites have recently been studied with increasing intensity due to their potential use in non-volatile ferroelectric random access memory, nano-electromechanical systems, energy-harvesting devices, advanced sensors, and in photocatalysis. This Review summarizes the current status of these 1D nanostructures and gives a critical overview of synthesis routes with emphasis on chemical methods. The ferroelectric and piezoelectric properties of the 1D nanostructures are discussed and possible applications are highlighted. Finally, prospects for future research within this field are outlined.

Fabrication of necklace-like structures via electrospinning

We report a one-step method to fabricate necklace-like structures from zero-dimensional materials via electrospinning. PVA was used as polymer matrix for accomplishing necklace-like arrays of silica particles. We systemically investigated how the diameter of SiO(2) particles, the weight ratio of PVA to SiO(2), the voltage, and the relative content of PVA/SiO(2)/H(2)O influenced the morphology of electrospun fibers. SiO(2) particles with diameter of 143 nm tended to aggregate into bunches in the fibers, while 265 and 910 nm SiO(2) particles tended to align along the fibers one by one, resembling necklaces. The content of water in the PVA/SiO(2)/H(2)O solution showed critical influence on the diameter of fibers and consequently determined the morphology. Too thin solutions gave birth to blackberry-like structure; too condensed solution was too hard to eject from the orifice of the needle; when the ingredient was elaborately tailored, we obtained necklace-like structures. We believe that these results can serve as references to generating other complex structures involving polymers and particles via electrospinning and that these structures will be potentially useful in photoelectric devices, drug release, and optical components.

One-dimensional composite nanomaterials: synthesis by electrospinning and their applications

This Review provides an overview of the synthesis of one-dimensional (1D) composite nanomaterials by electrospinning and their applications. After a brief description of the development of the electrospinning technique, the transformation of an inorganic nanocomponent or polymer into another kind of polymer or inorganic matrix is discussed in terms of the electrospinning process, including the direct-dispersed method, gas-solid reaction, in situ photoreduction, sol-gel method, emulsion electrospinning method, solvent evaporation, and coaxial electrospinning. In addition, various applications of such 1D composite nanomaterials are highlighted in terms of electronic and optical nanodevices, chemical and biological sensors, catalysis and electrocatalysis, superhydrophobic surfaces, environment, energy, and biomedical fields. An increasing number of investigations show that electrospinning has been not only a focus of academic study in the laboratory but is also being applied in a great many technological fields.

PbTiO(3) nanorod arrays grown by self-assembly of nanocrystals

Arrays of ferroelectric lead titanate (PbTiO(3)) nanorods have been grown on a substrate by a novel template-free method. Hydrothermal treatment of an amorphous PbTiO(3) precursor in the presence of a surfactant and PbTiO(3) or SrTiO(3) substrates resulted in the growth of PbTiO(3) nanorod arrays aligned perpendicular to the substrate surface. Two steps in the growth mechanism were demonstrated: first an epitaxial layer was formed on the substrate; this was followed by self-assembly of nanocrystals forming a mesocrystal layer which matured into arrays of PbTiO(3) nanorods.