A design of a nanooptical sensor, i.e. hybrid Bragg gratings over photonic crystal waveguide is proposed to monitor the strain, temperature, and vibration simultaneously. The shift in wavelength, i.e. red shift (towards the right) and blue shift (towards the left), is observed in response to applied strain, vibration, and temperature, respectively. The proposed sensor gives a better performance to measure the strain (with a 9 nm wavelength shift), temperature (with 8 nm wavelength shifting), and the vibration (with 10 nm wavelength shifting).

Carbonated hydroxylapatite represents one of the most important phases in bone tissues. This discovery led to many successful efforts to characterise its structure and properties at physico-chemical level, with the aim to employ this material in biomedical applications. It is possible to tailor the biomimetic character of hydroxylapatite by modifications of its crystal chemistry (vacancies and ionic substitutions), trying to match that of natural bone tissues. For this purpose, the authors investigated by ab initio quantum mechanics within density functional theory the structural, electrostatic potential features and water adsorption process on the (001) surfaces of mixed type A-B carbonate-substituted hydroxylapatite. The provided data are comparable to previous experimental and preliminary theoretical one on hydroxylapatite, and further extend the knowledge of the modulation of the water molecule adsorption onto carbonated hydroxylapatite caused by the CO₃ ²⁻ substitutions.

Novel visible (vis)-light-driven Bi₃O₄Cl plates were first prepared via a facile method. The structure, morphology, and photo absorption properties of as-prepared Bi₃O₄Cl were characterised by multiple physicochemical techniques. Tetracycline hydrochloride (TC-HCl), a famous broad-spectrum antibiotic, was used to evaluate the photocatalytic activity of the as-prepared samples. Compared to the BiOCl and solid-state reaction synthesised Bi₃O₄Cl, the plate-like Bi₃O₄Cl exhibited highly improved vis-light-driven photoreactivity toward TC-HCl degradation under aqueous solution. Moreover, the Bi₃O₄Cl plates also displayed excellent photochemical stability even after four times photocatalytic recycling tests. This work provides a simple approach to fabricate the novel Bi-based semiconductor for potential application in treatment of antibiotic pollutant.

TiO₂-WO₃ hollow spheres were successfully fabricated by a two-step synthesis method, which combines the polystyrene template-assisted method and chemical deposition method. Scanning electron microscope, energy dispersive spectrometer, and X-ray diffractometer were used to characterise the obtained products. The results indicate that the as-fabricated nanocomposites are double-shelled TiO₂-WO₃ hollow spherical structures. The photocatalytic properties of the obtained products were determined by the degradation of rhodamine B aqueous solution under simulated solar irradiation. The results reveal that the TiO₂-WO₃ hollow spheres and pure TiO₂ hollow spheres all have superior photocatalytic degradation ability. Compared with P25 nanoparticles and TiO₂ hollow spheres, TiO₂-WO₃ hollow spheres exhibit the best photocatalytic performance.

This work deals with a distinct concept to realise the junction-less tunnel field effect transistor (JL TFET) by creating the plasma of charges. The crux of this study is to reduce ambipolar conduction and to improve high-frequency figure of merits. To construct a JL TFET, initially silicon film is considered and then metal electrodes are used to form drain and channel region. The drain electrode is separated into two sections and the work function of section adjacent to channel is selected higher than the other section. This provides a non-uniform doping profile in the drain region creating large barrier at the drain/channel junction to prevent the ambipolar conduction. Ambipolarity is reduced to from at . The selection of work function and length of drain electrode adjunct to channel is crucial for optimising device performance. This optimisation provides information that work function >4.0 eV and length = 10 nm completely suppresses the ambipolarity which is around with little degradation in ON-current. The high work function for the section of drain electrode adjunct to channel provides lower gate-to-drain capacitance () and superior high-frequency responses. Furthermore, performance assessment at circuit level is done by implementing primary digital circuits as inverter and NAND logic with lookup table based Verilog-A model.

This work proposes a simple replication process of nanoimprint nickel stamp with the usage of Janus Green B (JGB) for the improvement of the filling effect to eliminate the voids forming in high aspect ratio nanotrenches during nanoelectroforming process. As JGB molecules tend to adsorb at the edge of the nanotrench with high electron density, the metal deposition rate is reduced at the edge of the nanotrench. Therefore, the voids are not formed due to the elimination of the sealing phenomenon during electrodeposition process. On the basis of the proposed process, a nickel nanoimprint stamp with six nanograting areas of 1.3 mm × 1.3 mm size, 200 nm pitch, 80 nm linewidth and 200 nm depth was replicated successfully. The experiment results demonstrate that the filling effect is gradually improved with the addition of JGB in the replication process of the nickel stamp.

Selection of ohmic contacts to Cu₂ZnSnS₄ (CZTS) films is one of the most crucial tasks involved in the fabrication of efficient CZTS devices. In the present work, the formation of ohmic contact with the p-type CZTS films was studied. The p-type CZTS thin films were fabricated by thermal evaporation, followed by the subsequent sulphurisation in the atmosphere of N₂ + H₂S (5%). Ag, In, Al and Ti were chosen as the metal electrodes of the CZTS-based films. The characteristics of CZTS thin films and the structure of Mo/CZTS/M (M = Ag, In, Al and Ti) were investigated using XRD, Raman, SEM, and EDX, to name but a few. The ohmic contact property of the studied material was tested using an I–V characterisation system. The results showed that Al could form a high-quality ohmic contact with the p-type CZTS films among the metallic electrodes.

This work proposed a novel nanomanufacturing approach, in which a submerged arc discharge method was adopted to produce graphene in deionised water. Graphene produced using this approach can be evenly dispersed and suspended in deionised water without the use of a surfactant or stabiliser, and is suitable for storage at room temperature. Ultraviolet–visible spectroscopy was employed to analyse the optical properties of the graphene nanostructure. The Zetasizer system was used to examine the particle size and zeta potential of the graphene nanoparticles, and scanning electron microscopy, energy-dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy were adopted to explore the morphology, size, and dispersion of the particles, using the Raman spectrum, it is observed that there are two characteristic peaks. Without mixing any surfactant or stabiliser in deionised water, the zeta potential of negatively charged graphene nanoparticles was −51.5 mV. The nanoparticles were stably suspended in the deionised water instead of depositing as sediments. The results of this work confirmed that graphene production with submerged arc discharge is a low-cost, fast, and effective manufacturing method.

Tunnel field-effect transistor (TFET) is considered to have superior device performance compared with DG-metal–oxide–semiconductor FET in terms of reduced off-state current and lower subthreshold swing. However, performance of a device solely depends on the accuracy in the fabrication process. This work presents a systematic methodology in small-signal-radio-frequency (RF) and linearity domain to analyse the effect of variation in lateral straggle caused by the variation tilt angle during ion implantation process. From previously published researches, it is intuitively established fact that the accurate evaluation of intrinsic components and estimation of linearity in short channel devices is crucial to access the range of application of the device. In this work, the authors have investigated the RF intrinsic parameter performances of a silicon double gate TFET having variation in lateral straggle from 1 to 5 nm. This study includes the analysis of non-quasi-static RF bias-dependent parameters such as intrinsic capacitances (C _gs, C _gd), gate-to-drain intrinsic resistance (R _gd) and intrinsic time delay (τ). Similarly, the device linearity and reliability are investigated here in terms of higher-order transconductances (g_{m 2} and g_{m 3}), VIP₂, VIP₃, IMD₃, IIP₃ and 1 dB compression point.

Composite ZrO₂-NiO powders synthesised, via the oxidation of Ni₄₀-Zr₆₀ alloy, and ball milled to sizes below 90 nm were spark plasma sintered. The isotherm levels, above the monoclinic–tetragonal (m–t) transition temperature in ZrO₂ (1170°C), were in the range 1200 and 1300°C. Microstructures with grain sizes between 100 and 900 nm were achieved. The X-ray diffraction patterns of the sintered samples revealed that the m–t transformation in ZrO₂ was preserved. The fraction of tetragonal phase, between 25 and 45%, increases with the isotherm level. Such partial stabilisation of the tetragonal phase is attributed to the presence NiO in ZrO₂.

Fundamental frequency analysis of rectangular piezoelectric nanoplates via the surface layer and non-local small-scale hypotheses is investigated in the present work. The piezoelectric nanoplate is under in-plane forces. The equilibrium governing of piezoelectric nanoplates is attained via the two variable refined plate hypothesis, and then the equations of motion are achieved utilising Hamilton's principle. To solve these equations, the finite difference method is employed. To verify the exactness of the finite difference method, the governing equations are tested by the Navier's solution. Numerical results show a good accuracy among the outcomes of the present work and some accessible cases in the literature. The numerical results show that for negative residual surface stress, as the boundary condition becomes stiffer the effect of surface layer increases, while for positive one that phenomenon is inverse.

This work presents wafer-level vacuum-encapsulated silicon resonators that utilise movable electrodes and arc welding in order to achieve deep sub-micron transduction gaps. The devices are fabricated using micro-electro-mechanical systems (MEMS) integrated design for inertial sensors (MIDIS) process, a commercial pure-play MEMS process, offered by Teledyne DALSA Semiconductor Inc.. The default minimum transduction gap in the MIDIS process is 1.5 μm. Here, the work introduces a technique to permanently reduce the transduction gap of the resonator using localised arc welding to a designed width of ∼200 nm. The prototype Lamé mode resonators are encapsulated in an ultra-clean 10 mTorr vacuum cavity that ensures long-term stability. The quality factor was measured to be 1.37 million at a resonance frequency of 6.89 MHz. With the narrower gap, the motional resistance of the resonators is reduced by a factor of ten times.

In this work, a new electrochemical immunosensor for the detection of alpha-fetoprotein (AFP) was developed by using glassy carbon electrode modified by prussian blue-carbon nanotubes@ polydopamine (PB-CNTs@PDA). PB was used to load and coated by CNT and PDA, respectively, to increase the conductivity and specific surface area of nanocomposite, and to prevent the unstable and outflow of PB on the surface of electrode. Additionally, gold nanoparticles were synthesised on the surface of PB-CNTs@PDA dependent on excellent reduction ability of PDA coating without any other reducing agents, which provided a favourable microenvironment to increase the loading capacity of antibody without deactivation. Under optimal experimental conditions, the immunosensor shown excellent detection performance with a wide dynamic response range of AFP concentration from 0.005 to 80 ng ml⁻¹ and a detection limit of 0.001 ng ml⁻¹ (S/N = 3). The proposed electrochemical immunoassay method provides potential applications for other antigens or tumour markers in clinical diagnosis.

Formaldehyde is a toxic water-soluble organic matter. Its detection methods and detection limit have been attracting more attentions. An AC electrokinetic (ACEK)-enhanced capacitive sensing method for rapid detection of trace formaldehyde in liquid is presented using commercial microelectrode chips. By this method, a detection limit is achieved as low as 0.01 ppm (μg/ml) within a 60 s response time. It is proved that the trace amount of formaldehyde in common solvents can also be effectively detected. As a complement, the capacitance change rate dependence on testing voltage and frequency is investigated. Compared to other existing detection methods, this ACEK-based capacitive method is a low cost, high sensitive and fast detection means, which shows a great application prospect in industry and research such as food safety and specimen cleaning.

Super-aligned conductive material is a hotspot in the research of flexible and transparent conductive films. This work introduces a facile and rapid ‘TEG-sol’ method to synthesise Ag nanoparticles and their orientational alignment. Pure, well-crystallised Ag nanoparticles with polyhedron morphology are fabricated by reducing silver nitrate in TEG (triethylene glycol) solvent. Fourier transform infrared spectroscopy result reveals an organic coating layer on the surface of the Ag nanoparticles, which promotes the excellent dispersibility of these nanoparticles in TEG solvent. Orientational Ag nanoparticle alignment is obtained by spin coating the dispersion on copper foil. This proposed process provides a brand new idea for the design and fabrication of conductive microstructures.

The hierarchical micro/nano structures are successfully obtained on the stainless steel mesh via a simple laser direct writing technology. The as-prepared mesh reveals excellent superhydrophilic/underwater superoleophobic properties or superhydrophobic/superoleophilic properties after 1H, 1H, 2H, 2H-perfluorodecyltriisopropoxysilane modification. According to the oil density, the superhydrophilic/underwater superoleophobic mesh allows water to permeate and repels the light oil. Its oil/water separation efficiency is as high as 98.5% for the light oil. The superhydrophobic/superoleophilic mesh can be easily wetted by heavy oils while the water will be repelled, which the separation efficiency can reach 98.0% for the heavy oil. Moreover, this special wettability mesh can still maintain high separation efficiency after 20 separation cycles, which indicates the good separation stability.

Hydrogenated titanium dioxide (H-TiO₂) has drawn much research attention in the photocatalysis society since it has significantly improved solar absorption and enhanced photocatalytic activity. Nevertheless, the key factor that leads to the enhanced photocatalytic performance of H-TiO₂ is still debatable. To clarify this issue, the structural properties of H-TiO₂ and its effects on photogenerated charges are investigated. Mesoporous H-TiO₂ was subjected to different hydrogenation temperatures rate under the flow of purified H₂ gas and its photocatalytic activities are evaluated by reactive black 5 photodegradation. The H-TiO₂ pretreated at different temperatures seems to have a detrimental effect on photocatalytic activity as compared with that of untreated H-TiO₂. Further investigations reveal that H-TiO₂ treated at high temperature can cause the formation of less photoactive rutile phase and agglomeration that leads to the inhibition of their photocatalytic activity.

Design and fabrication of structurally optimised conductive materials are important for many energy applications. Here is reported a carbon(C)@polyaniline(PANI)@silver(Ag) core-double-shell microspheres with good conductive performance. These three components formed a well-defined core-double-shell configuration that was distinct from simple core-shell or hybrid structures. Synergistic effect from respective components (C, PANI and Ag) offers the polyurethane (PU) material a high electrically conductive performance. The C@PANI@Ag microsphere can significantly reduce the surface resistivity of PU and maintain the structure stability. The surface resistivities of PU/C@PANI@Ag composites were even lower than those of PU/C composites and PU/C@PANI composites. These encouraging results showed their great potential in flexible and wearable electronics.

Fabricating small-sized Si nanoclusters has been considered as an effective approach to obtain a high figure-of-merit of thermoelectric materials. To reveal the electron and phonon transport in the Si nanoclusters with different geometric shapes, the electronic structure, the lattice dynamics and the thermoelectric properties of Si nanobox, Si nanocylinder, Si nanosphere and Si nanotetrahedron were investigated through first-principles calculation, lattice simulation and Boltzmann transport theory. The influences of the electronic structure and the lattice dynamics on the thermoelectric properties were also studied in detail. Therefore the work provides a complete understanding on the thermoelectric transport in the Si nanoclusters with different geometric shapes. Moreover, a largely enhanced figure-of-merit (ZT) at 1200 K of 1.70 has been achieved for Si nanobox.

A drug delivery system based on ɛ-polylysine-modified titania nanotube (ɛ-PL-TNTs) arrays was prepared. Polylysine on the nanotubes’ surface can effectively bind with alendronate, a drug for the treatment of osteoporosis, through chemical bond. The bonds are fairly stable in an acid environment and cannot easily break up in a physiological environment. The ɛ-PL-TNTs increased the amount of drug loading by 9% in weight. The in vitro release profile of alendronate from ɛ-PL-TNTs showed a significant reduced burst release and an extended overall release of more than 15 days.

An innovative semiconductor power vertical double-diffused MOSFET (VDMOS) is proposed for the first time with the SiC/Si heterojunction at the P-base and N-drift region (called for SiC/Si VDMOS), which improves the trade-off between the breakdown voltage (BV) and specific on-resistance (R _on,sp). The ‘soft’ Si material has been combined with the ‘hard’ SiC material to play their own advantages for SiC/Si VDMOS. The Si has been formed above the 6H-SiC substrate to make up the channel and source electrode, and the 6H-SiC is underneath the P-base to form the SiC/Si heterojunction. The novel terminal technology of breakdown point transfer has been advanced for the first time and applied to SiC/Si VDMOS, which transfers the breakdown point of SiC/Si VDMOS and improve the BV compared with Si VDMOS. The simulated results have been shown that the optimised BV of proposed SiC/Si VDMOS is increased from 226 to 578 V compared with the conventional Si VDMOS with the same drift region length, which is because the breakdown point is transferred from the higher electric field area with the maximum curvature radius to the low electric field area. The simulated R _on,sp of SiC/Si VDMOS is 17.4 mΩ·cm² with the BV of 578 V, which is lower than that of 41.01 mΩ·cm² with the BV of 226V in Si VDMOS. The silicon limit relationship has been broken for SiC/Si VDMOS.

Leaf-like macroscopic ZnO nanostructures have been synthesised via a conventional thermal evaporation method at 950°C, using a mixture of graphite, zinc oxide and CuO powders as a source material. The effect of CuO in a relevant growth mechanism was discussed. Its crystal structure properties were determined using X-ray diffraction, scanning electron microscopy and high resolution transmission electron microscopy. Photoluminescence spectra of the sample exhibit emission peaks centred at about 382, 525, 542 and 767 nm, respectively. The room temperature ferromagnetism was observed using a physical property measurement system.

The intercalated anion species of layered double hydroxides (LDHs) largely determine their application performance. This work investigated the ion exchange process from CO₃ ²⁻- to NO₃ ⁻-type LDHs in aqueous medium using the ammonium salt method, and found that a complete ion exchange reaction can be performed by heat treatment. The weak acidity of aqueous NH₄NO₃ solutions can protonate the interlayered CO₃ ²⁻ to HCO₃ ⁻ and then NO₃ ⁻ intercalates for the charge compensation; heating at temperatures above 80° C enables the double hydrolysis of HCO₃ ⁻ and NH₄ ⁺ to CO₂ and NH₃ gases, which is proposed to be a kinetically indispensable factor to complete the NO₃ ⁻/CO₃ ²⁻ ion exchange. The heating treatment could reduce the salt dosage and greatly shorten the reaction time to 1 h. In the ion exchange process, mass losses of ZnAl-LDHs take place due to the dissolution of hydroxide layers, and the dissolution rate of Zn increases with an increase in the heating time, but Al is hardly dissolved. The present work also demonstrated that the proposed method can be appropriate for a complete ion exchange of SO₄ ²⁻ or I⁻ for CO₃ ²⁻.

Tb³⁺ and Yb³⁺ codoped GdBa₃B₉O₁₈ phosphors were synthesised by high-temperature solid-state method. The intensity of visible emission decreases with the increasing of the Yb³⁺ concentration. While in the infrared range, the emission peaks at 980 and 1018 nm which originate from the ²F_5/2→²F_7/2 transition of Yb³⁺ are observed and the intensity increases with the increasing of Yb³⁺ concentration till 10 mol%. So the cooperative energy transfer from Tb³⁺ to Yb³⁺ is demonstrated. Based on emission spectra and luminescence life time measurements, the intrinsic quantum efficiency was calculated to approach 139%.

The work develops a novel method for the detection of bisphenol A (BPA) based on glutathione (GSH)-protected silver sulphide quantum dots (Ag₂S QDs), which was simple, fast, non-toxic, sensitive and selective. Ag₂S QDs were synthesised with a sulphur–hydrazine hydrate complex as the S²⁻ source and GSH as the stabiliser. Ag₂S QDs, near-infrared QDs, offered the advantages over lower background fluorescence and lower signal loss. The fluorescence peak of Ag₂S QDs at 650 nm was quenched significantly in the presence of BPA. Good linear correlations were obtained over the concentration range from 0 to 60 μM of BPA under optimised conditions. The developed selective and sensitive method presaged more opportunities for the application in environmental samples.

This work reported a simple route for preparing CeO₂/CeF₃ composite powders. Cerium nitrate hexahydrate, oxalic acid dihydrate and ammonium fluoride were milled and subsequently calcined to obtain the composite powders. X-ray diffractometer, field emission scanning electron microscope, transmission electron microscopy, zeta potential tester, and polishing test were utilised to characterise those products and study the effect of doped fluorine amount on their physicochemical characteristics and chemical mechanical polishing properties. The results show that incorporation of 7 wt% fluorine into the starting materials can change the particle morphology from large sheet for pure CeO₂ into uniform spherical particles with size of 30–50 nm. The composite powder with 7 wt% fluorine exhibits great suspension stability and relatively high material removal rate. Meanwhile, this slurry facilitates obtaining smoother surface after polishing, which may be related to the changes of particle morphology and decrease in overall hardness of abrasives.

A lead dioxide electrode is obtained by anodic oxidation and applied to supercapacitors. Scanning electron microscopy (SEM) results show that the conductive substrates of graphite/Pb possess a three-dimensional porous structure after electrochemical expansion. Electrochemical results reveal that the prepared graphite/Pb conductive substrates (GPCSs) exhibit a high-specific capacitance and good electrical conductivity. To improve the performance of the electrode, a layer of active lead was deposited on the other surface of the GPCSs. Pb particles were dispersed evenly on the surface of the substrate from the SEM image. Finally, the hybrid supercapacitor was assembled with a PbO₂ positive electrode and a lead negative electrode. At the beginning of the charge and discharge, the voltage was set to 2.4 V. During this process, the active Pb deposited on the surface of the substrate was oxidised to PbO₂ gradually to form a PbO₂/(graphite/Pb) hybrid capacitor. The specific capacity of the capacitor can reach 120.4 F/g. After a period of 3000 cycles, the capacity still reached up to 104 F/g, and the capacity retention rate increased up to 87%. These values indicate good cycling stability.

Novel nanocomposite, in which nickel–titanium (Ni–Ti)-layered double hydroxide (LDH) nanoplates were deposited on the surface of graphene nanosheets (GNSs), was synthesised by a simple in situ crystallisation technique. Owing to the introduction of GNS and the formation of layered heterostructure, the visible (vis)-light absorption was enhanced, while the recombination probability of photogenerated electron–hole pairs was decreased. As a result, the obtained Ni–Ti LDH/GNS composite showed an enhanced vis-light photocatalytic performance for the degradation of methylene blue. The corresponding photocatalytic mechanism was discussed according to the active species capture experimental results, which indicated that the active species of ^•OH was the most crucial one while O₂ ^•− and h⁺ were the less crucial ones. This work may provide an insight for designing graphene-based layered photocatalysts with a high performance.

The high-crystallinity, large-grain and full-coverage CH₃NH₃PbI₃ thin films are successfully prepared by converting the PbI₂·dimethyl sulphoxide (DMSO) complex thin films at the optimum annealing temperature and time of 140°C and 10 min in the glove box with the relative humidity of 10–15%. The influence of the annealing temperature and time on the crystallinity, surface morphology, optical absorption of CH₃NH₃PbI₃ thin films is systematically investigated and the photovoltaic performance of the corresponding TiO₂ nanorod array perovskite solar cells is evaluated. The results reveal that the crystallinity of CH₃NH₃PbI₃ thin films can be improved and their grain sizes gradually increase from 200–300 to 300–500 and 500–800 nm with the increase of the annealing temperature from 100 to 120 and 140°C. The TiO₂ nanorod array perovskite solar cells with the optimum annealing temperature and time of 140°C and 10 min exhibit the best photoelectric conversion efficiency (PCE) of 16.11% and the average PCE of 15.62 ± 0.49%.

The mix-faceted Cu₂O nanoparticles with tunable {111} and {100} facet ratios were successfully prepared by a facile method. In this experiment, the as-synthesised Cu₂O photocatalysts with different {111} and {100} facet ratios were more active than the sole {111} or {100} faceted Cu₂O. The optimised Cu₂O photocatalyst with 68% {100} facet displayed the highest visible light photocatalytic activity for hydrogen production, which was about 4.53 and 5.89 times as high as that of Cu₂O nanoparticles with the single (100) and (111) facets. Besides, possible photogenerated electrons and holes transfer mechanism of the mix-faceted Cu₂O was proposed in detail.