This review will focus on the synthesis, arrangement, structural assembly, for current and future applications, of 1D nanomaterials (tubes, wires, rods) in 2D and 3D ordered arrangements. The ability to synthesize and arrange one dimensional nanomaterials into ordered 2D or 3D micro or macro sized structures is of utmost importance in developing new devices and applications of these materials. Micro and macro sized architectures based on such 1D nanomaterials (e.g. tubes, wires, rods) provide a platform to integrate nanostructures at a larger and thus manageable scale into high performance electronic devices like field effect transistors, as chemo- and biosensors, catalysts, or in energy material applications. Carbon based, metal oxide and metal based 1D arranged materials as well as hybrid or composite 1D materials of the latter provide a broad materials platform, offering a perspective for new entries into fascinating structures and future applications of such assembled architectures. These architectures allow bridging the gap between 1D nanostructures and the micro and macro world and are the basis for an assembly of 1D materials into higher hierarchy domains. This critical review is intended to provide an interesting starting point to view the current state of the art and show perspectives for future developments in this field. The emphasis is on selected nanomaterials and the possibilities for building three dimensional arrays starting from one dimensional building blocks. Carbon nanotubes, metal oxide nanotubes and nanowires (e.g. ZnO, TiO2, V2O5, Cu2O, NiO, Fe2O3), silicon and germanium nanowires, and group III–V or II–VI based 1D semiconductor nanostructures like GaS and GaN, pure metals as well as 1D hybrid materials and their higher organized architectures (foremost in 3D) will be focussed. These materials have been the most intensively studied within the last 5–10 years with respect to nano–micro integration aspects and their functional and application oriented properties. The critical review should be interesting for a broader scientific community (chemists, physicists, material scientists) interested in synthetic and functional material aspects of 1D materials as well as their integration into next higher organized architectures.

Assembly of one dimensional inorganic nanostructures into functional 2D and 3D architectures. Synthesis, arrangement and functionality

One-step synthesis of lightly doped porous silicon nanowires in HF/AgNO3/H2O2 solution at room temperature

Structural, magnetic and optical properties of Ni-doped TiO2 thin films deposited on silicon(1 0 0) substrates by sol–gel process

Silicon nanowires (SiNWs) with a length of about 8 μm and zinc oxide nanorods (ZnONRs) with a length of about 200 nm were prepared by wet chemical etching and chemical bath deposition, respectively. Capacitive humidity sensors based on ZnONRs/SiNWs were fabricated and their humidity sensing properties were examined at room temperature (∼25 °C). The largest response range of the sensors is 2.40–64.40 nF when the relative humidity (RH) changes from 11.30 to 97.69%. The sensitivity is 0.69 nF/% RH. The longest response and recovery time is ∼26 and 7 s, respectively, which corresponding to 97.69% RH. The sensors are proven to have long-term stability, with a maximum relative standard deviation (RSD) of 2.93% corresponding to 11.30% RH during about one month at room temperature in air. ZnONRs/SiNWs are a better ideal capacitive humidity sensing material compared to those we previously reported. It might be easy to miniaturize and compatible with traditional integrated circuit (IC) process.

Capacitive humidity sensors based on zinc oxide nanorods grown on silicon nanowires arrays at room temperature

This chapter deals with bottom-up strategies that allow one to prepare amorphous assemblies of metal nanoparticles. Within these assemblies the nanoparticles couple to each other, affecting the effective electromagnetic properties of the materials. As a consequence, besides the properties of the individual particles, parameters such as number of individual particles within the assembly, geometry of the assembly and average distance between particles within the assembly can be used to design the optical properties of a material. It is therefore highly desirable to control these parameters with high precision, which is the art of self-assembly. Compared to top-down lithographic methods the bottom-up self-assembly approach is cheap and enables the fabrication of large area two-dimensional or three-dimensional samples, making it attractive for applications. In the following, after an introduction, different strategies that were used in the past to assemble nanoparticles into defined structures are briefly discussed. Such strategies rely on templates such as liquid crystals, DNA or surfactants. A versatile approach, which relies on charge-driven self-assembly mediated by charged surfaces and polyelectrolytes, is then discussed in more detail. This approach easily allows one to build large scale amorphous layered structures of nanoparticles with high control of parameters such as distance between particles within one layer and distance between the layers. The method is not restricted to flat surfaces and can be used to coat for example silica beads, resulting in core–shell structures. An attempt has also made to rationalise the observed optical properties in terms of coupling between particles within the different assemblies, thus paving the way to the design of materials with novel electromagnetic properties.

Bottom-up Organisation of Metallic Nanoparticles

Structural and optical characteristics of silicon nanowires fabricated by wet chemical etching

Synthesis and magnetic properties of nickel nanoparticles deposited on the silicon nanowires

The invention discloses a preparation method of a nickel nanometer particle/silicon nanometer wire magnetic composite material, comprising the steps of: developing a silicon nanometer wire on a silicon wafer; and then depositing nickel nanometer particles on the silicon nanometer wire to obtain the nickel nanometer particle/silicon nanometer wire magnetic composite materials; the nickel nanometer particles of the material are spherical nanometer particles with uniform size, and the diameters of the nickel nanometer particles are 35-40 nm; the nickel nanometer particles are singly dispersed on the surface of the silicon nanometer wire with a diameter of 20-300 nm and a length of 70-75 microns and are independent to each other without interference; and the nickel nanometer particles have the magnetic characteristics such as high blocking temperature (370 K), high coercive force and low saturation magnetization intensity and the like (when the blocking temperature is 5 K, the saturation magnetization intensity is 4.5 emu/g, and the coercive force is 375.3 Oe; and when the blocking temperature is 400 K, the saturation magnetization intensity is 2.6 emu/g, and the coercive force is 33.3 Oe). The preparation method is simple, low in cost, high in repeatability, low in requirement for preparation environment and suitable for large-scale industrial production. The prepared nickel nanometer particle/silicon nanometer wire magnetic composite material can be applied to the fields of magnetic nanometer materials, nanometer magnetic storage and the like.

Preparation method of nickel nanometer particle/silicon nanometer wire magnetic composite material

The invention discloses a method for controlling growing lengths of silicon nanowires. According to the method, a water bath kettle is used for heating so as to control a growing temperature of the silicon nanowires and the growing lengths of the nanowires are controlled by controlling the temperature, and thus, the problem that in the prior art for preparing the silicon nanowires by a wet etching process, the silicon nanowires with large length-width ratios are difficult to generate is solved. The method disclosed by the invention has simple and reliable process and low cost, can be used for batch production and lays a foundation for preparing a nano device on the basis of the silicon nanowires with different length-width ratios.

Method for controlling growing lengths of silicon nanowires

Abstract The polymer with imine bonds (C═N) synthesized by condensation of aldehydes and amines was called polyimine. Graphene nanoplatelets (GNPs) were blended into polyimine by imine dynamic chemistry, and GNPs/polyimine (GNPs-P) composites were fabricated by heat-pressing. A series of thermal and mechanical properties have been tested for the matrix and GNPs-P composites. Thermogravimetric analyzer showed that the GNPs were able to improve the thermal stability of the GNPs-P composites. From the test of mechanical properties, GNPs-P composite with 0.5 wt% GNPs was superior to the matrix in bending and tensile properties. The bending and tensile strengths were 92.65 and 73.05 MPa, with an improvement of 18% and 5%. GNPs-P composites with 1 wt% GNPs showed the most significant advancement in impact properties, reaching an impact strength of 11.745 kJ·m−2 with a gain of 21.6%. Cross-sectional observations using scanning electron microscope proved that the GNPs-P composites have brittle fractures. A small number of GNPs could synergize with the matrix by bridging the cracks, creating a crack diffusion resistance and a load transfer reinforcement effect, which improved the mechanical properties of the GNPs-P composites.

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Yun Chen

Papers

Structural and optical characteristics of silicon nanowires fabricated by wet chemical etching

Synthesis and magnetic properties of nickel nanoparticles deposited on the silicon nanowires

Preparation method of nickel nanometer particle/silicon nanometer wire magnetic composite material

Method for controlling growing lengths of silicon nanowires

Mechanical properties and thermal analysis of graphene nanoplatelets reinforced polyimine composites