In this reported work, Ag/AgCl nanohybrids were synthesised through a facile solid–liquid reaction approach by reducing pre-grown AgCl nanocubes with a sodium borohydride (NaBH₄) ethanol solution. The morphology of the AgCl nanocubes' precursor is kept very well after the reactions. The influence of the NaBH₄ concentration and the injection speed of NaBH₄ solution were studied. It is demonstrated that the prepared Ag/AgCl nanohybrids can serve as effective surface-enhanced Raman scattering (SERS) substrate. Rhodamine 6G (R6G) as the typical SERS analyte was applied to determine the effect of the Ag/AgCl substrate, and SERS signals of R6G were observed in a low concentration of 1 × 10⁻¹² M. Furthermore, the Ag/AgCl substrate was applied to detect other analytes such as crystal violet and 4-mercaptobenzoic acid, which also show high sensitivity.

A series of inverse-microemulsion quasi-ternary system phase diagrams of CTAB + n-butanol + n-hexane + brine (MgCl₂/CaCl₂) is systematically drawn by adjusting the ratio of MgCl₂ and CaCl₂. On this basis, a microemulsion has been prepared with five different molar ratios of magnesium ions to calcium ions, and a calcium carbonate and magnesium carbonate coprecipitation product is obtained by reaction with an equimolar amount of sodium carbonate. The samples were characterised by scanning electron microscopy (SEM), a Fourier transform infrared (FTIR) spectrometer and X-ray diffraction (XRD). The SEM photographs indicated that when the content of Ca²⁺ was higher, some large fusiform aggregates of coprecipitation particles were formed in solution, but with the content of Mg²⁺ increased gradually, they eventually formed small and uniform sphere particles. The measurement results of XRD and FTIR indicated that the crystal structures of calcium carbonate in coprecipitation changed gradually from vaterite into aragonite and finally turned into being amorphous with the increasing of the proportion of magnesium ions.

The water-based dispersion of ultrafine leather fibres was firstly prepared in the authors' laboratory by high-pressure homogenisation. The hybridisation method of ultrafine leather fibres and SiO₂ particles was used to eliminate the serious agglomeration of ultrafine leather fibres, and finally the dry hybrid leather powder (HLP) was obtained successfully. The morphology of the HLP was investigated using scanning electron microscopy (SEM). The micrograph of SEM revealed that the leather fibres were coated with a layer of scattered SiO₂ particles and still maintained their intrinsic fibrous structures. Surface element analysis (energy dispersive X-ray spectrometry) confirmed that the SiO₂ particles were anchored on the surface of the leather fibres. Furthermore, the formation of bonding effect between the leather fibres and the SiO₂ particles was also demonstrated by X-ray photoelectron spectrometry measurement. The obtained leather fibres were observed to be approximately less than 30 μm in length and 70 nm in width. X-ray diffraction analysis and thermogravimetric analysis were also used to investigate the characterisation of ultrafine leather powders, and one of the results showed that the HLP had greater thermal stability than leather shavings.

Three-dimensional (3D) hierarchical cobalt microstructures with a leaf-like shape were prepared using cobalt chloride as the starting material via a facile solution method at 90°C. An ethanol and water mixed solution was used as the solvent, and hydrazine was employed as the reducing agent. The phase purity and morphologies were investigated by X-ray diffraction and scanning electron microscopy. It was found that the concentration of alkaline and the volume ratio of ethanol to water played important roles for the shape control of the final products. Magnetisation measurements revealed that the leaf-like cobalt microstructures exhibited ferromagnetic characteristics with a saturation magnetisation of 156.2 emu/g and an enhanced coercivity of 371.5 Oe at room temperature. This relatively simple, efficient and shape controllable approach can be extended to the preparation of other metal materials with complex 3D micro/nanostructures.

In this reported work, carbon/montmorillonite (C/MMT) nanometre particles and micrometre particles blended were extracted by the froth flotation method, extraction and density gradient centrifugation. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and particle size analysis were employed to characterise the C/MMT extracted before and after. The results have shown that the froth flotation method cannot effectively collect C/MMT nanocomposites, and the extraction is not effective, whereas density gradient centrifugation can collect vari-size grained C/MMT nanocomposite particles. On using density gradient centrifugation, the thicknesses of C/MMT nanocomposite particles are <20 nm.

The results of this reported work indicate that the precursor plays a significant role as well as surfactant in the hydrothermal synthesis of high-quality silver nanoparticles (AgNPs). To address the existent stability difficulties in the long-term storage and application conditions of AgNP hydrocolloids, silver diamminohydroxide ([Ag(NH₃)₂]OH) is attempted as the silver precursor instead of conventional silver nitrate (AgNO₃), which has been widely utilised. A simple green synthesis approach of size controllable quasi-spherical AgNP hydrocolloid using glucose reducer and dextran surfactant is experimentally adopted as a demonstration. Experimental results show that under the same synthesis conditions, [Ag(NH₃)₂]OH precursor-based AgNP hydrocolloid products perform with much higher stability than AgNO₃ based products. Also, the monodispersity of products is considerably improved.

Black silicon was fabricated on a pyramid silicon surface via reactive ion etching (RIE) through a Cu micromask formed by a sputtering and annealing process. This adopted RIE technique does not rely on oxygen gas avoiding the silicon surface damage from oxygen plasma. Scanning electron microscopy and an UV–vis-NIR spectrophotometer were used to characterise the morphology and optical reflectance of the prepared samples with porous structures on a pyramid. The results show that the homogeneity of the Cu micromask controlled by the annealing condition determines the reflectance of the textured silicon wafer. A lowest reflectance of 6.2% appears in the samples with sputtered Cu thin film annealed at a temperature of 500°C for 10 min. This work may provide a choice to fabricate black silicon with an excellent light confinement structure, which will have potential application for the improvement of efficiency of silicon solar cells.

ZnO core–shell microspheres were fabricated by a facile one-pot hydrothermal method without any other surfactant or template. The structure, morphologies and properties of the as-prepared samples were determined using X-ray diffraction, scanning electron microscopy and ultraviolet (UV) and visible absorption spectroscopy. Results showed that the zinc ions were first adsorbed onto the surface of a sucrose droplet or included in the droplet and then reacted with each other to form a ZnO crystal nucleus, which was followed by the growth and calcination steps to form ZnO core–shell microspheres. The photocatalytic characterisation revealed that ZnO core–shell microspheres behave high photocatalytic activity for methylene blue under UV light irradiation, and the degradation rate can reach to 97.64% in 210 min.

In this reported work, scanning probe microscopy is used to perform localised oxidation of Ti as a bottom-up nanofabrication method. The effects of normal force setpoint and oxidation voltage on oxide nanofeatures during atomic force microscopy (AFM) mode and scanning tunnelling microscopy (STM) mode oxidation are investigated. The normal force between the probe and sample and electrochemical current in the anodic oxidation process are measured using a custom control system, and the effects of these variables on the size and resistivity of oxidised nanopatterns are investigated. It is shown that a direct relation exists between oxidation voltage and written oxide resistivity as well as written feature width in the STM mode oxidation. In AFM mode oxidation, the normal force setpoint is shown to have a positive correlation with feature size, but an inverse relation with oxide resistivity. By leveraging the presented system's ability to operate in both AFM and STM mode, the dynamics and feature fabrication dependencies are shown to be a continuum of writing voltage and normal force. This reported work suggests that STM and AFM mode oxidation can be thought of as similar processes but working at different operating points in terms of normal force and tip-surface spacing.

In this reported work, the effects of repeater insertion on the electrical performance of carbon nanotube (CNT) interconnects are studied theoretically. It is shown that the time delay of CNT interconnects, when the length becomes larger than the transition length, can be effectively suppressed by inserting a series of equispaced repeaters. Furthermore, the impact of contact resistance on the repeater insertion is examined and compared. As the single-walled CNT interconnects can endure large contact resistance, its optimal repeater insertion can be determined analytically by neglecting the contact resistances. However, for multi-walled CNT interconnects, the contact resistance must be taken into account in the design of optimal repeater insertion when it exceeds a certain value.

Template-based methods are a commonly used way to prepare superhydrophobic surfaces, in which, one of the critical issues, is template fabrication. In this work, a template with a dual-scale hierarchical structures fabrication method is investigated, in which, using the Cr and photoresist as etching mask, the fused silica glass substrate is etched in a buffered hydrofluoric solution. Optical photos and atomic force microscopy (AFM) scans show that the excellent ordered and uniform microstructures with a feature size less than 4 μm combining with the nanostructures with a feature size of about 20–30 nm on the etched surface have been fabricated, indicating hierarchical structures being obtained. Then the template with dual-scale structures is used as a master template and experiments of pattern transferring to PDMS and photoresist by cast moulding and by imprint lithography, respectively, have been conducted. The duplicating fidelity is characterised through optical photos and AFM scans. The contact angles of water on various fabricated surfaces are characterised and the influence of the surface roughness on wettability has been discussed.

To avoid the potential adverse effects of chemically-synthesised gold nanoparticles (AuNPs), a new method is developed for their biosynthesis using watercress total extract (WTE) and it is compared it with the citrate-based method. Synthesised AuNPs were characterised using transmission electron microscopy (TEM), particle size analysis and infrared spectroscopy (FTIR), and the mechanism and biocompatibility of WTE-based AuNPs were evaluated by MTT assay. The colour of the WTE-based AuNPs was directly changed from yellow to deep red without any intermediate colour change and spectrophotometric analysis showed significant differences in absorbance as well as peak surface plasmon resonance of synthesised AuNPs as compared with the use of sodium citrate. Formation of AuNPs in the WTE-based method was faster than the method using citrate. TEM pictures showed similar sizes of the AuNPs obtained by both methods, but WTE-based AuNPs were more spherical and the range of sizes provided minor differences with TEM results. FTIR confirmed the involvement of WTE compounds in the structure of AuNPs during biosynthesis and the MTT assay did not show any considerable anti-growth effect of WTE-based AuNPs on target cells. Hence, it seems clear that WTE-AuNPs could be used for various biological-related purposes including drug delivery, diagnosis and treatment of various diseases.

High-purity (99.9+%) nanosize Cr₂O₃ was produced from chromite concentrates. Sodium dichromate was produced from an alkaline melt of chromite ore and then nanosize Cr₂O₃ was obtained by reaction between sodium dichromate and sulphur. Nanooxides were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. The size of particles was 50–148 nm. The nanoparticles show a loosely agglomerated structure. The presented method is simple and economical.

Conventional solvent and thermal enhanced oil recovery techniques are less competitive, because of the presence of resin and asphaltene components which are difficult to remove; therefore it is imperative to develop new types of catalysts for the efficient recovery of heavy oil. In this reported research, silica-supported nanoscale zero valence iron (denoted as SiO₂/nanoFe) is adopted as a catalyst to break the C–S bonds of resin and asphaltenes so as to reduce the viscosity of heavy oils and acquire enhanced oil recovery. A target SiO₂/nanoFe catalyst was prepared via liquid-phase reduction of ferric chloride hexahydrate by sodium borohydride in the presence of surface-modified silica as a support. The as-prepared SiO₂/nanoFe catalyst was characterised by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectrometry. The dispersibility of as-prepared SiO₂/nanoFe catalyst in various organic solvents was evaluated, and its specific surface area was determined using classic Brunauer-Emmett-Teller isotherm method. Moreover, the catalytic performance of the SiO₂/nanoFe catalyst for the aquathermolysis process of a heavy oil sample collected from Shengli Oilfield (Dongying, China) was evaluated. It was found that as-prepared SiO₂/nanoFe, composed of silica with an average size of about 10 nm and zero valence iron nanoparticles with an average size of several nanometers, exhibits good anti-oxidation stability. The SiO₂/nanoFe catalyst also exhibits good catalytic performance for the aquathermolysis process of heavy oils; in particular, at a mass fraction of 1.0%, it can significantly reduce the viscosity of a tested heavy oil from 184 to 42 Pa·s, showing promising potential in the industrial production of heavy oils.

Programmable circuit components are indispensable for nanomagnet logic (NML, also called magnetic quantum-dot cellular automata) devices. Two alternative programmable majority gates (PMGs) (PMG1 and PMG2) for in-plane NML are proposed. The presented designs both utilise trapezoid shape nanomagnets (nanomagnet with a slanted edge) to form the structures. With only a uniform layout and a homogeneous clocking field, the proposed structures can orderly reconfigure eight input combinations of the majority gates, and they also demonstrate superior performance over the regular shape nanomagnet-based PMG. The innovative design could find technological application in the field of majority gate-based programmable magnetic circuits (e.g. programmable nanomagnetic Full Adder).

Presented is a novel process of benzo-cyclo-butene (BCB) bonding for a wafer level package with ‘stamp’ printing, in which the BCB structure is transferred and patterned by pressing the cap wafer towards another wafer with a liquid BCB layer. Compared with the conventional BCB bonding process, this new method not only avoids the residual polymer inside the cavity to extend the application of BCB bonding in the complex three-dimensional structures but also raises the bonding strength because of the non-treatment before bonding. The key process parameters, such as the auxiliary wafer material, pre-curing time and bonding pressure were optimised after a series of contrast experiments. The bonding quality was evaluated qualitatively by manual separation and quantitatively by a tensile bonding test. This new method has a minimum bonding strength of 5.9 MPa, which is more than ten times the conventional one. Besides, the bonding yield reaches 80% in five groups of 4-inch wafers. Finally, this process was successfully utilised in an acceleration microswitch.