A facile and green route to prepare reduced graphene oxide (RGO) is reported. The graphite oxide is firstly pretreated by detonating exfoliation in muffle furnace at low temperature and then is completely reduced to RGO in hydrogen atmosphere at high temperature, namely two-step method. Extensive characterisations show that the as-prepared RGO with high ratio of C/O and surface area consists of crumpled and few-layer thick graphitic sheets. The RGO is used to electrocatalyse nitrobenzene (NB) to P-aminophenol (PAP). High catalytic activity and stability obtained in the electrochemical measurement indicate that the RGO could be a promising alternative catalyst toward the electroreduction of NB to PAP.

A novel step-oxide super junction-lateral double-diffused metal–oxide–semiconductor field-effect transistor (SOSJ-LDMOS) structure is proposed and optimised which allows the high breakdown voltage (BV) and low-specific on-resistance (R _on,sp). The proposed structure overcomes the effect of thick field oxide formed by shallow trench isolation process in conventional buffer layer SJ-LDMOS (N-buffered SJ-LDMOS), effectively enhancing the performance of the SJ-LDMOS. Thanks to the SO layer, a new electric field peak has been introduced in the surface electric field distribution, which makes the lateral surface electric field uniform in the off-state. Moreover, due to the thinner oxide layer, in the on-state the majority of electron current is accumulated near the top surface under the field plate and the thinner oxide layer also provides a wider current flowing path. In the virtue of integrated systems engineering (ISE) simulation, not only has the BV of SOSJ-LDMOS been increased, but also the R _on,sp has been reduced simultaneously compared with the N-buffered SJ-LDMOS in the same drift length. In addition, when SOSJ-LDMOS and N-buffered LDMOS are at the same BV, the R _on,sp of SOSJ-LDMOS is decreased by 26.3–38.9%, compared with the N-buffer SJ-LDMOS.

A graphene cantilever beam of arbitrary shape by patterning suspended graphene using a focused ion beam (FIB) is fabricated. Suspended graphene was formed by transferring graphene over a trench structure and patterned the suspended graphene into a cantilever beam structure. When the suspended graphene is patterned by an FIB, the high-ion irradiation of FIB deforms the shape of the cantilever beam; in contrast, low-ion irradiation cannot penetrate the suspended graphene. An evaluation of the ion irradiation dose of the FIB and the damages caused to the suspended graphene confirmed that in the case of few-layer graphene with a maximum of three layers, optimum processing can be performed by an ion irradiation of 6 × 10¹⁶ ions/cm². Under this condition, a graphene cantilever beam with a width of 1.34 μm and a length of 2.13 μm could be fabricated. Furthermore, the Raman spectroscopy results indicate that the FIB process does not significantly change the properties of the graphene.

Heterogeneous catalysis of Fenton-like process provides new alternatives to overcome the drawbacks of traditional Fe²⁺-H₂O₂ system. Herein, the modification of Fe₃O₄ with SiO₂/C in one-pot hydrothermal reaction to prepare Fe₃O₄/SiO₂/C nanoparticles (FSCNP) for the Fenton-like catalysis in neutral environment is reported. FSCNP could catalyse the decomposition of H₂O₂ at various pH values to decolourise methylene blue (MB), in particular the neutral pH 7.5. Correspondingly, the chemical oxygen demanding of MB solution was significantly removed. FSCNP-H₂O₂ system was resistant to radical scavengers. Higher H₂O₂ concentration and temperature would accelerate the decolouration of MB in FSCNP-H₂O₂ system. The implications to the future applications of FSCNP in dye decolouration and water treatment are discussed.

A super-hydrophobic ceramic surface with excellent adaptability to the natural environment was developed on a metal substrate through a facile electrophoretic deposition approach. Alumina, as a demonstrating low cost ceramic material, was electrophoretically deposited on a steel surface to form a hierarchical surface structure. After the treatment with stearic acid, the as-fabricated surface exhibits a high water contact angle and very low sliding angle, revealing a super hydrophobicity. Furthermore, the surface can maintain the super hydrophobicity with liquids of different pH values, performing good natural environment adaptability.

The impregnation of nanoclay with TiO₂ was carried out by new and fast method. Nanoclay was submitted only to a single step molten salt process. Scanning electron microscopy showed that TiO₂ nanoparticles precipitated over the nanoclay surface after treatment. Structural characterisation of nanocomposite by X-ray diffraction displayed the change of basal peak after even 1 min process at both temperatures. UV-visible spectroscopy showed the presence of TiO₂. However, the band gap was not affected by process temperature and time. XRF graphs revealed that by increasing temperature and time of the molten salt process, the amount of loaded titanium dioxide on the nanoclays was enhanced. Through this quick process, an inexpensive nanocomposite with properties comparable with those from more elaborate processes is produced.

Different pressures of 80 and 90 MPa were applied to produce Y₂O₃ ceramics by spark plasma sintering in this work. Effects of pressure were investigated on densification, microstructure, infrared (IR) transmission and mechanical properties. It was found that applying higher pressure led to finer microstructure and consequently higher hardness and fracture toughness. An IR-transparent Y₂O₃ ceramic with 60% transmission at wavelength of 5 µm was obtained by sintering at 1300°C under uniaxial pressure of 90 MPa. This sample had an average grain size of 0.76 µm and hardness and fracture toughness of 9.37 GPa and 1.60 MPa.m^1/2, respectively.

The design, fabrication and characterisation of a high-speed electrothermal linear micromotor for microelectromechanical systems safety-and-arming devices are presented. The micromotor consists of a microspring, a barrier plate and four V-shaped electrothermal actuators with microlever amplifications. The whole device is fabricated on a silicon-on-insulator wafer with a 50 µm device layer and the fabrication process is introduced. The micromotor has been successfully operated at a speed of 35.66 mm/s over a range of 500 µm with an output force of 5.27 mN under the applied voltage of 23 V. The chip area of the fabricated micromotor is about 19.20 mm², which means the micromotor can be easily integrated with other microdevices. The linear micromotor performs well in driving force, mechanical strength and working speed, which signifies the proposed device is suitable for safety-and-arming devices.

Since there is currently no method to selectively fabricate superhydrophobic regions on superhydrophilic surfaces of metal substrates, wettability patterns on metal substrates are prepared via the three-step technique including superhydrophilic, superhydrophobic and selectively superhydrophilic modifications. Here, an innovative method that can selectively lower surface energy of superhydrophilic surfaces, and thereby makes it more convenient to fabricate the wettability patterns, is proposed. Chemical etching is used to formulate micro/nanoscale rough structures and fabricate superhydrophilic aluminium (Al) surface, which is then covered by patterned mask whose main composition is siloxane. Removing the mask after 80°C water bath heating for 20 s, the covered Al surface has been modified to become superhydrophobic (contact angles >165°, sliding angles <1.5°), while the uncovered region is still superhydrophilic, and wettability patterns are therefore obtained. Fourier transform infrared spectrophotometer and Raman spectra indicate that the change of wettability is induced by hydrophobic groups on the modified surfaces. The superhydrophobic surfaces fabricated by this method have excellent high-temperature resistance. The method proposed is simple, rapid and environmental-friendly.

Radio-frequency (RF) attenuators show unique advantages and a great development potential in phased array radars. A kind of programmable step attenuators with high precision based on contact-type microelectromechanical system series switches is proposed herein. This work paid attention to the design and fabrication of switches – the key components of attenuators. By setting up vent holes on the pull-down plates of switches, the mass of plates was reduced, together with the decreased influence of air damping. Meanwhile, switches were manufactured and packaged through ultraviolet lithography (UV-LIGA) technology with the S parameter test being performed. Results showed that the insertion loss in a range of 0.3 and 1.8 dB under the condition that attenuation modules are short-circuited at the same time, which is basically the same with the simulation results of 0.1–1.3 dB. While all the return losses S11 were <15 dB expect from that at 10 dB. In addition, the designed attenuator showed gentle attenuation in a range of DC ∼20 GHz. However, on the whole, the deviation is controlled within 2 dB, which is basically consistent with the design results of 1 dB. It can be found from the obtained results that all indices of the attenuator satisfied the design requirements.

SnO₂/ZnO core–shell nanofibres were synthesised by single-stage electrospinning technique. For synthesis of these nanofibres, the hydrophilic solutions of precursors were injected by two injectors through coaxial needles which were connected to separate syringes. The precursor's solutions were prepared by solving zinc acetate and tin chloride in polyvinyl alcohol solution, separately. The morphology and structure of nanofibres were observed by field emission scanning electron microscope, transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction techniques, before and after calcination. The final core/shell structure of the nanofibres was established as SnO₂/ZnO, after calcination. Average diameters of the as-eletrospun and calcined core/shell nanofibres were about 190 and 97 nm, respectively.

Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT) polymer has been investigated to elucidate the resistive-switching properties in a sandwiched structure of indium tin oxide (ITO)/F8BT/aluminium (Al). An active layer of F8BT polymer was deposited on the ITO-coated polyethylene terepthalate through spin coating. Morphologically, the layer was characterised with field emission scanning electron microscope. The fabricated sample showed resistive-switching properties within ±5 V with an OFF/ON ratio of 10:1. The switching characteristics were attributed to the transition of trap-limited space charge-limited conduction (SCLC) to trap-filled SCLC. It is shown through energy band diagram that memory effects in the fabricated sample were due to the trapping of electrons in the F8BT active layer that were injected from the top Al electrode.

Parallel plate actuators (PPAs) are widely used actuators in microelectromechanical systems. A PPA can be utilised as a passive/active vibration isolator. A novel active vibration isolator with a simple structure, which requires a constant voltage source and series capacitor, is proposed. The principle of the spring softening effect is analysed, which can avoid a specific external disturbance by changing its resonant frequency. A simulation study was performed to verify the feasibility of this type of isolator.

A nanocrystal zeolite X with intracrystalline mesopores has been successfully prepared by using organofunctionalised mesoporous silica in hydrothermal system. The as-prepared zeolitic material persist the inherent framework structure of FAU zeolite, and present a crystallographic morphology of stacked three-dimensional intergrowths made up of rectangular nanocrystals. The intracrystalline mesopores are formed via a bond-blocking principle with hydrophobic carbon chains of organosilane inhibiting the growth of zeolite units and crystals in the channels of mesoporous silica during hydrothermal synthesis. The results showed that the zeolitic material has a considerable external surface area (247 m²g⁻¹)and mesopore volume (0.44 cm³g⁻¹), maintaining high Brunauer–Emmett–Teller surface area (991 m²g⁻¹) and large total pore volume (0.71 cm³g⁻¹), and clearly stating a larger adsorption capacity for p-xylene at relative higher pressure.

Micro-electro-mechanical systems (MEMS) typically have low damping ratios. Although it benefits many applications because they require low energy loss, this characteristic generates large overshoots and long settling times to reach steady state. A feedback posicast controller that can improve the performance of MEMS electrostatic actuators is proposed. This method inserts a posicast controller inside the feedback loop and combines it with a proportional–integral controller. The advantages of this technique include easily implemented control laws, additional velocity sensors or estimators are not required and the parametric adjustment of the controller is less sensitive to the model's nonlinearity. A numerical study verifies that the proposed method is valid.

An explicit three-dimensional (3D) finite-element model for dilute nanofibre networks is presented. The model takes into account 3D structure of networks by mimicking nanomanufacturing process. Realistic elasto-plastic behaviour of individual nanofibres with failure and frictional interfibre contacts are incorporated. The model is capable of predicting through failure mechanical behaviour of nanofibre networks with large fibre reorientation and fibre breaks. Comparison of simulated force–strain behaviour with experimental data showed that predicted and experimental curves exhibited similar shapes consisting of an elastic stage, a strain-hardening stage, and a softening stage, with abrupt drops coincident with fibre breaks. The numerically predicted maximum tensile force and total failure strain were of the same magnitude as experimental results. The developed explicit model can be used to study the effects of fibre diameter and mechanical properties, network density, fibre orientation distribution, and contact conditions on mechanical behaviour of nanofibre networks. Such studies can shed light on the mechanisms of complex nonlinear deformation and failure of networks and can be used for networks design and optimisation for applications.

CdS and ZnS co-sensitised one-dimensional TiO₂ nanofibres were successfully prepared by a combination of electrospinning and successive ionic layer adsorption and reaction (SILAR) process because both electrospinning and SILAR method are inexpensive and scalable techniques. The composites of CdS-ZnS/TiO₂ heterojunctions were compared with electrode containing only CdS being superior in terms of photoelectrochemical tests. The results showed that the photocurrent of CdS-ZnS/TiO₂ nanofibres was seven times than that of CdS/TiO₂ nanofibres and seven times than that of pure TiO₂ nanofibres. The increased photocurrent is depended on the preparation order of ZnS and CdS on TiO₂ nanofibres.

The electrical properties of diketopyrrolopyrrole ethyl-hexylated (DPP(TBFu)₂) thin film sandwich structure of the ITO/DPP(TBFu)₂/Al configuration for different annealing temperatures ranging from 40 to 130°C is investigated. The current–voltage characteristics showed an excellent rectifying behaviour of the device, and from which the diode parameters were extracted. It is found that all parameters remain constant upon annealing temperatures, with the exception of the turn-on voltage. An increase of the turn-on voltage from an initial value of 1.6–2.08 V is noticed starting from 70 to 100°C, respectively. This fact is attributed to the effect of residual solvent induced defect states that may act as free carriers. Defect states density for the non-annealed and annealed device at 130°C derived from capacitance–voltage measurements is found to correlate well with the turn-on voltage. It is found that annealing the device at 130°C results in a smaller concentration of defect states. In addition, it is also found that the annealing process produces the flat band voltage drop, which has a direct impact on the turn-on voltage.

High figures of merit is important and necessary for thermoelectric materials in a particular engineering application of thermoelectric generation. Crystalline is an important factor for the high figures of merit of thermoelectric materials. Single-crystalline structure Sb/Bi₂Te₃ supperlattice nanowires (SLNWs) were synthesised in large quantity by pulsed electrodeposition technology using porous anodic alumina oxide as a template. The X-ray diffraction result indicates that the as-prepared compound consists of rhombohedral phase Bi₂Te₃ and monoclinic phase Sb. Transmission electron microscope images demonstrate that the segments of SLNWs are built by Bi₂Te₃ and Sb alternately and exhibit the distinguished interface between two segments. The average diameter and length of each segment are about 80 and 90 nm, respectively. The composition of neighbouring segments was investigated by selected area electron diffraction (SAED), further verifying that the neighbouring segments of SLNWs are comprised of Bi₂Te₃ and Sb. Meanwhile, the spot pattern of SAED indicates these segments are crystallised well.

The buckling of elastically restrained embedded microbeam under axial compression load is researched. The effects of small size, axial compression load and surrounding elastic medium are taken into account at the same time. Winkler elastic foundation approach is used to simulate the interaction between microbeam and elastic medium. Fourier sine series is employed for the simulation of microbeam deflections. A coefficient matrix is obtained with the aid of applying Stokes' transformation to corresponding boundary conditions. The buckling characteristics of elastically restrained embedded microbeams are investigated in some numerical examples. There are very good agreements between this study and the previous results indicating the validity of the presented method.

Silver@poly(vinyl pyrrolidone) (Ag@PVP) core–shell nanoparticles are synthesised via a one-step method. Ag@PVP/poly(vinylidene fluoride) (PVDF) composites with desirable dielectric properties were reported. It was found that the dielectric losses for Ag@PVP/PVDF composites were rather low similar to that of pure PVDF because of the insulating PVP coating. The Ag@PVP/PVDF with PVP of lower molecular weights exhibited more desirable dielectric properties than those with PVP of higher molecular weights. PVP can offer interesting permittivity enhancements without significantly adversely affecting the dielectric losses of the PVDF matrix. The results of this work make it possible to obtain the percolative composites with low dielectric loss and high permittivity by using Ag@PVP through simple methods.

Tungsten trioxide (WO₃) thin films are of great interest as counter electrodes in electrochromic (EC) devices such as ‘smart window’ for energy-efficient buildings. Uniform WO₃ nanoplates filmed as EC working electrodes were fabricated on seed-free fluorine-tin-oxide (FTO) coated glass via a facile and addictive agent-free hydrothermal process. The WO₃ nanoplates were characterised by scanning electron microscopy and the X-ray photoelectron spectroscopy. The morphological analysis of the film showed that the WO₃ nanoplates lying on the FTO glass uniformly. Fourier transform infrared spectroscopy was applied to study the vibrational information of the sample. Furthermore, uniform WO₃ nanoplates exhibit well performance of EC properties. Owing to the highly two-dimensional nanostructure, a fast switching speed of 12 and 3 s for colouration and bleaching are achieved for WO₃ film. These properties of the WO₃ nanoplates film endow its promising practical applications in smart windows.

Two kinds of hierarchical ZnO flower-like porous nanostructures with numerous nanosheets were successfully synthesised through a template-free and low-cost oxalic acid assisted solvothermal method combined with a heat post-treatment. The obtained products were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM results revealed that the two kinds of products had sword-like and hydrangea-like nanostructures originating from water and water/alcohol mixture solvents, respectively. XRD results confirmed that the growth process of ZnO involved a phase transformation from intermediate compound zinc oxalate hydroxide to ZnO. Furthermore, the photocatalytic properties were also characterised. The results indicated that both samples exhibited high photocatalytic activities for the degradation of rhodamine B, which were mainly ascribed to the porous hierarchical structures.

Titanium dioxide (TiO₂) film was deposited by DC pulse magnetron sputtering technique. The surface of TiO₂ film was implanted by N ion beam at room temperature and N doped TiO₂ (N-TiO₂) film was obtained. X-ray diffractometer result showed that with the increase of sputtering power, the crystal structure of TiO₂ film changed from amorphous to anatase polycrystalline structure. Transmission electron microscopy result revealed that nanoscale clusters existed in amorphous TiO₂ film. The bandgap of TiO₂ film was about 3.28 ± 0.05 eV. X-ray photoelectron spectroscopy results revealed that N ion was doped into TiO₂ film as Ti–N and Ti–NO bonds. With increasing TiO₂ film crystallinity, N atom-percent and ratio of Ti–N to Ti–NO decreased and increased, respectively. TiO₂ film deposited with 900 W in sputtering power, N atom-percent decreased to 6.6 at.% and ratio of Ti–N to Ti–NO increased to 0.81:1. The bandgap of N-TiO₂ film was about 3.02 ± 0.07 eV. N atom-percent and ratio of Ti–N to Ti–NO kept at 2.73 ± 0.26 at.% and (0.87 ± 0.03):1 for all annealed N-TiO₂ films. The bandgap of annealed N-TiO₂ film was about 3.16 ± 0.03 eV. So, the crystallinity of TiO₂ film was one of most important parameters, which influenced the chemical bond structure and chemical stability of N in TiO₂ films.

One of the significant advantages of the ultraviolet (UV) light exposure of chalcogenide glasses (ChGs), photodoping process, is in the application of programmable metallisation cells (PMCs) as a novel non-volatile resistive memory. The memory state of a PMC is dictated by the formation or dissolution of a metallic filament in a ChG film between active metal and inert metal contacts. Owing to relatively rigid covalent bonds mixed with soft van der Waals interconnections, ChGs are able to form acceptor-like traps where electrons are absorbed, and therefore electron mobility decreases compared with crystallised structures. The role of electrons in the interaction with ionic species in ChGs is inevitable. One the other hand, holes are considered as majority carries and their role in interaction with the system is also significant. Therefore, knowing carrier mobility in ChGs is essential. To extract carrier mobilities, for the first time a circuit setup accompanying with time constant extraction method for Ge₃₀Se₇₀ as a ChG material without and with UV light exposure is proposed. Owing to being straightforward, this method can be applied to other ChG materials as well as other light sources or even ionising radiation particles.

Epoxy/silica micro and nanocomposites are prepared and subjected to multiple accelerated stresses along with neat epoxy for 9000 h in a specially fabricated chamber. Leakage current measurements were recorded after each weather cycle. Dielectric strength was also evaluated according to ASTM-D149 after each 1000 h ageing. In the course of ageing time, neat epoxy was found with high dielectric loss and random rise in leakage current. In the case of both micro and nanocomposites, these properties indicated improvements over neat epoxy. By applying regression technique over leakage current measurements, relatively longer service lives of epoxy composites were estimated.

Synthesising gold nanoprobes in the near infrared (NIR) region is of particular interest in developing nanosensors due to the minimal light attenuation from biomolecules. Here, the controlled synthesis and tunability of gold nanostars’ two distinct localised surface plasmon resonances (LSPRs) at around 700 and 1100 nm is reported. By using UV–Vis–NIR absorption measurements and finite-difference time-domain calculations, the induction of the LSPR and the multipolar nature of the resonances have been investigated experimentally and theoretically. Simulation results demonstrate that large electric fields are confined at the tips of the branches, where the LSPR can be induced specifically by controlling the polarisation of the incident electric field. The surface-enhanced Raman scattering (SERS) capability of these dual plasmonic gold nanostars (DPGNS) has also been demonstrated using a Raman reporter, diethylthiatricarbocyanine iodide and high SERS enhancement factor (EF) of 2 × 10⁷ is obtained with 785 nm excitation. With ease of synthesis, LSPR at NIR and high SERS EF, DPGNS demonstrated the capability to be an effective SERS substrate and the potential to elicit the highest SERS EF ever reported for gold nanoparticles, with further longer wavelength excitations at and beyond 1064 nm.

A simple, low-cost and reliable dicing-free silicon-on-insulator (SOI) process is presented for solving three major challenges in manufacturing the microelectromechanical systems devices, i.e. stiction, notching and dicing damage. In this process, the cavity is used and patterned on the handle layer to solve the stiction problem, and the exposed oxide is removed in hydrofluoric acid (HF) solution before deep reactive ion etching (DRIE) on the structure layer to eliminate the notching effect's impact. The dies are attached temporally to a designed frame by the silicon dioxide. After removing the oxide using HF solution, the dies are separated from the wafer cleanly without dicing damage. The layout design rules on the front side and backside patterns are established. Furthermore, a grooved carrier wafer with specific design rules was introduced to enhance the yield rate of the process. Finally, a tuning fork gyroscope was fabricated to demonstrate the proposed fabrication process and a yield rate of over 81% was achieved. The process solves the stiction, notching and dicing damage problems only involving the apparatus associated with lithography and DRIE, offering an economic and complete SOI process solution.

The theoretical analysis and simulated design of a plasmonic equilateral triangular dielectric resonator nantenna fed via a 1 × 2 corporate feed network are presented. Utilising full wave electromagnetic simulation software Computer Simulation Technology (CST) Microwave Studio (MWS) and verifying results via high-frequency structure simulator, the working of the proposed nantenna at optical C-band (1.55 μm) is demonstrated and confirmed. Numerical results prove that the proposed nantenna exhibits a directivity of 9.57 dB with an impedance bandwidth of 2.58% (189–194 THz) covering the standard optical C-band transmission window. Furthermore, by selecting the appropriate orientation of the triangular dielectric resonators, the proposed nantenna structure can be tuned to operate at the higher or lower optical bands offering a threshold value of directivity and bandwidth Δf. By tuning the nantenna they achieve an increase in bandwidth of 4.96% (185.1–194.7 THz) and directivity also improves to 9.7 dB. The wideband and directive properties make the proposed nantenna attractive for a wide range of applications including broadband nanophotonics, optical sensing, optical imaging and energy harvesting applications.

A new generalised model of the electrowetting of microfluids has been proposed. Instead of the conventional Young–Lippmann formula, dynamic minimising of the total energy of system which is superposition of capillary free energy and electric energy has been utilised to calculate the contact angle as indicator of wetting behaviour. The change of interfacial energy of liquid/solid interface and change in relative permittivity of solution in the presence of colloid particles have also been considered in the developed model. The model predicts that contact angle saturation decreases in the presence of colloid particles both in DC and AC conditions. The model also predicts that the reduction of contact angle by applying potential is higher in the case of TiO₂/water microfluidic system which is in agreement with experimental data reported in literature.