Bi₂O₃ nanosheet was synthesised using China rose petal as a biotemplate for the photodegradation of methylene blue under xenon lamp irradiation. The samples were characterised by thermogravimetric analysis–differential scanning calorimetric analysis, Fourier-transform infrared spectroscopy, nitrogen adsorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and ultraviolet–visible diffuse reflectance spectroscopy. The results revealed that the Bi₂O₃ nanosheet with pure monoclinic phase was successfully synthesised by replication of the petal template with a thickness of about 100 nm, and showed the absorption thresholds wavelength of 480 nm. Moreover, the Bi₂O₃ nanosheet exhibited 94.84% degradation efficiency of photodegradation of methylene blue in 180 min, which was much more active than that of the commercial α-Bi₂O₃ due to its high specific surface area of 45.7 m² g⁻¹ and wide band gap of 3.10 eV.

Tetragonal YVO₄ nanoparticles of different sizes were successfully prepared through an ethylenediaminetetraacetate -mediated hydrothermal method. The crystalline structure and optical property were characterised by transmission electron microscopy (TEM), high resolution TEM, X-ray diffraction, photoluminescence spectra, and ultraviolet–visible diffuse reflection spectra, respectively. The as-prepared YVO₄ displayed excellent photocatalytic performance. Among them, sample S2 has the highest photocatalytic activity with a photodegradation efficiency of 85% within 180 min illumination, which is due to its smaller size and larger specific surface area. The investigation on the photocatalytic mechanism reveals that hydroxyl radical (•OH) is the main active species in the photocatalytic oxidation process.

Cobalt (Co)-based tungsten carbide (WC) wear-resistant coatings with different content of WC were prepared on the surface of Q235 low carbon steel by plasma-transferred arc welding. The properties of the coatings such as strengthening mechanism, microhardness and wear properties were tested by using a metallurgical microscope, scanning electron microscope, energy dispersive spectrometer, X-ray diffraction, Rockwell hardness tester, and friction wear equipment. The results show that the main reasons for the strengthening of spray welding layer are the solution strengthening formed by α-Co with supersaturated tungsten (W) and the dispersion strengthening caused by eutectic precipitated carbide and silicide. The proportion of the solid solution of W in α-Co steadily ranges from 18.00 to 19.59%. The morphologies of rich W-phase are mainly related to the content of W. With the content of W increasing, the evolution process of the shape is the amorphous form→damascene shape→star-like shape→the polygon. Amorphous W-rich phase can be obtained when the content of WC ranges from 20 to 30%, evenly distributed W-rich phase in the shape of damascene or star can be obtained when the WC content ranges from 30 to 40%, and the polygonal W-rich phase can be obtained at the percentage of 40–50%.

Existing oxidation–absorption denitration processes have some disadvantages such as high cost, equipment corrosion and low oxidant utilisation ratio. In this work, a novel denitration process with a microbubble gas–liquid dispersion system (MBGLS) was proposed. The nitric oxide (NO) removal effects of MBGLS based on the various absorbents containing hydrogen peroxide (H₂O₂), salinity and metal ions were investigated. The results showed that the MBGLS had an excellent NO removal performance because of hydroxyl radicals (·OH) released by the MBs. H₂O₂, NaCl, Fe²⁺ and Mn²⁺ could enhance the removal properties of MBGLS, but excessive NaCl was not conducive to the removal of NO. Under the optimal reaction conditions (absorbent pH = 8, 330 K, 0.4 mol/l H₂O₂ and 800 ppm NO), the NO removal efficiency reached 87.7%. This new process is highly cost-effective and environment friendly and shows a good commercial application prospect in flue gas denitration.

This work reports the synthesis of Ni_1−x Zn _x Fe₂O₄ ferrite (where x = 0, 0.1, 0.3, and 0.5) by a facile solution combustion method, using oxalyl-dihydrazide as a fuel. Owing to stoichiometric mixing of the starting materials and dissipation of heat during the combustion process, nano-sized spinel ferrites have been synthesised. Fourier transform infrared spectroscopy studies were carried out to confirm the presence of metal-oxide bands in spinel ferrites. X-ray powder diffraction analysis confirmed the presence of a single phase cubic nanocrystalline nature of ferrite samples. Energy dispersive X-ray spectroscopy studies showed the purity of ferrite samples. The effect of Zn substitution on the magnetic properties of these ferrites is also reported here. Magnetic studies revealed that the saturation magnetisation for these ferrite powders increases up to x = 0.3 (38.73 emu/g) and then decreases. Mössbauer measurements revealed a gradual transition from a ferrimagnetic to a superparamagnetic character with increasing concentration of Zn.

Cobalt phosphide/reduced graphene oxide (Co₂P/RGO) nanocomposites were synthesised successfully via a facile in-situ solvothermal method. Co₂P nanoparticles with a mean size of 80 nm anchor uniformly and firmly on the surface of RGO nanosheets, which not only avoid the aggregation of Co₂P nanoparticles, but also prevent the restacking of RGO nanosheets. Used as a degradation agent, the as-prepared composites exhibit superior adsorption degradation activity for various organic dyes. As an anode material for Li-ion battery, the Co₂P/RGO composites also show good electrochemical properties and its initial discharge specific capacity of the as-prepared composites can achieve to 900 mAh/g. The reason might be attributed to the interfacial interaction and the effective combination of Co₂P nanoparticles with RGO nanosheets.

In this work, the thermal evaporation method was adopted to prepare Nd-doped Mg₂Si semiconductor thin films on n-Si(111) substrate. The structure, morphology and optical properties of these Mg₂Si thin films doped with Nd were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Raman spectroscopy (RAMAN). The XRD results showed that Nd dopant led to weakened Mg₂Si diffraction peaks and bigger lattice constants. The scanning electron microscopy results indicated decreased size of Mg₂Si grains and clusters formed by the grains because of Nd dopant. The RAMAN results showed that the intensity of the characteristic peaks near 256 and 690 cm⁻¹ decreased due to the influence of Nd doping.

A series of boron-doped-titanium dioxide (B-TiO₂) nanospheres were synthesised via a mild and facile spray-drying process. The obtained nanospheres were relatively uniform with a size of about 100 nm. A strong absorption in the visible-light range was observed due to the formation of Ti–O–B bonds, by narrowing the bandgap of B-TiO₂ from 3.1 to 2.8 eV. The as-synthesised 3 wt% B-TiO₂ exhibited the greatest photocatalytic activity in the degradation of p-nitrophenol. The photocatalytic performance was improved, which could be attributed to high absorption of the visible-light region and efficient separation of photogenerated electron–hole pairs.

Scanning ion conductance microscopy has a widespread application in imaging non-conductive substrates, especially biological samples due to its high-resolution and non-contact imaging. In this work, state-of-the-art achievements on exploring samples’ surface properties including surface morphology, sample conductivity and dynamics using scanning ion conductance microscopy are firstly introduced, which confirm that scanning ion conductance microscopy is such a mature technology that realises non-invasive and high-resolution imaging. Then, combinations with scanning electrochemical microscopy and atomic force microscopy are demonstrated, which realise the multifunction of scanning ion conductance microscopy. Furthermore, improvements that can help enhance the imaging rate are presented. Finally, the future direction of scanning ion conductance microscopy is discussed.

The Ni(OH)₂/NiOOH nanoparticles (NPs) electrodeposited on a glassy carbon electrode (GCE) in Ni(NO₃)₂ and NH₃·H₂O aqueous solution for the electrode materials. Then the nickel hydroxide/oxyhydroxide acetate was formed in acetate solution. The effects of deposition conditions such as the concentration of Ni(NO₃)₂ solution, the number of sedimentary cycles, the concentration of acetate in the soaking liquid and the soaking time are discussed in detail. The electrochemical properties of the material have been investigated by cyclic voltammetry, Tafel curve, EIS and amperometric i–t curve techniques. The result displays excellent electrocatalytic activity towards the electrocatalytic oxidation of urea in alkaline solution. Furthermore, the modified electrode for oxidation reaction has the advantages of simple preparation, good electrochemical properties and stabilisation.

An inductively coupled plasma etching process for delineation of InAs/GaSb type-II superlattice pixels is presented. An optimised etch recipe without alternate plasma cleaning step showed an etch rate as high as 0.11 μm/min that results in smooth vertical sidewalls for the type-II superlattice pixel arrays with 10 μm pitch size and 2.4 μm deep trenches. At 70 K, the dark current density for the mesa etched + SU-8 polymer passivated type-II superlattice photodiodes was found to be 0.11 A/cm² at an applied reverse bias voltage of 0.2 V. The activation energy of 13 meV obtained from the Arrhenius plot and a variable area diode array technique showed that the measured dark current is mainly attributed to bulk tunnelling current. This technique of mesa delineation for the type-II superlattice pixel arrays with small pitch size is a viable option in realising next-generation infrared focal plane arrays.

Generally, anatase titanium dioxide (TiO₂) exhibit better photocatalytic activity than rutile TiO₂. In the present work, Ag modified TiO₂ were prepared by a simple sol–gel method and the photocatalytic activity of pure TiO₂ was enhanced via adding Ag. Moreover, Ag modified rutile TiO₂ shows the best photocatalytic activity compared to Ag modified anatase TiO₂ and pure TiO₂ owing to the lowest recombination rate of photogenerated pairs and the most surface hydroxyl groups.

In this work, NPC (nanoporous carbon) is purposely employed to accommodate the semiconductor CdSe QDs (quantum dots) in the absence of any capping agent to facilitate the visible-light photocatalyst CdSe QDs@NPC composite. CdSe QDs@NPC composite has been achieved by the facile method of the incipient-wetness deposition, and furthermore characterised by powder X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The results of TEM and HRTEM show that CdSe QDs are implanted into NPC and bound to several nanometres. Both X-ray diffraction and HRTEM indicate that the as-synthesised CdSe QDs belong to the cubic phase. The photocatalytic performance of CdSe QDs@NPC composite has been evaluated by degrading the RhB under visible-light irradiation. NPC as electron acceptor and transport channel can enhance the synergism of CdSe and NPC by improving the electron–hole separation. Furthermore, the photocatalytic mechanism exhibits that h⁺ and O₂ ^−• species are the decisive, active species in the degradation process of RhB.

A diffuser/nozzle is one of the most frequently-used channels in a valveless piezoelectric micropump, but its efficiency has not been satisfactory. Hence, optimisation of the channel structure is of great significance. The concave tuning diffuser/nozzle element can obtain steady flow rectification under different Reynolds numbers, and its efficiency is much higher than the conventional diffuser/nozzle element whose diverging angle is >25°. Therefore, the application of concave tuning on the micropump is promising and worth anticipating. In this work, the experiment and numerical simulation were carried out under the conditions of voltage (50–250 vpp), excitation frequency (10–1000 Hz) and Re_c (100–1000). The results show that the performance of a micropump with concave tuning is better than that with a straight sidewall, as the pump efficiency is improved significantly. The position and size of vortexes are of great significance to the pump efficiency of the micropumps. The distribution of pressure in the micropumps with concave tuning and straight sidewall was displayed. With the increase of characteristic Reynolds number, the adverse pressure gradient occurred. Compared with the straight sidewall, the concave tuning structure can better withstand adverse pressure gradient and delay the boundary layer separation in the channel.

The TiO₂ modified carbon nanotube composites (TiO₂/CNT) and Ag deposited ternary multilayered composites (Ag/TiO₂/CNT) were prepared by chemical deposition and sonochemical reaction, respectively. The composites were characterised by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and ultraviolet–visible (UV–vis). The results showed that anatase TiO₂ layers were wrapped on the surfaces of the CNTs. The face-centred-cubic structure of Ag nanoparticles (NPs) was dispersedly formed on the surfaces of the Ag/TiO₂/CNT composites. The expected formation and good dispersion of Ag was obtained by high-intensity ultrasound irradiation assistance. All the resulted TiO₂/CNT and Ag/TiO₂/CNT composites exhibited a higher photocatalytic performance than that of TiO₂ for the degradation of methylene blue. The novel nanocomposite photocatalysts were developed through structural changes and double effects of carbon materials and noble metals as electron acceptors. Inhibited recombination of electron-hole pairs allows effective electron transfer and active redox reaction on the surfaces of the composites. The novel composite combines the CNTs with excellent electronic nature and nobel metallic NPs with the special semiconductor-metal junction. It can provide new guidance for the application of carbon nanotube-based photocatalytic materials in photocatalysis field from UV–vis spectrum.

The human body is considered as a rich source of energy in the forms of body motion, heat etc. These energies can be trapped to develop a viable energy source, which confines the long-term serviceability. The battery drove wearable systems suffer from critical issues such as weight, limited lifespan and lack of biocompatibility. It is the main hurdle in gaining market acceptance for wearables. Rapid growths of wearable for biosensing motivate them to use it for health monitoring. This work describes the complete fabrication flow for low-cost energy harvesting device as an alternative power source for wearable biomedical diagnostic system with prime focus on biocompatibility, deformability and conformability. The conversion of body motional energy into electrical energy is carried out using zinc oxide piezoelectric material, polydimethylsiloxane substrate and silver fabric electrodes. The estimated power demand of the biomedical sensing modules lies in the range of 1–100 μW. It is observed that optimum power can be harvested when the device is placed between socks fabric and foot sole. The power level of 106 µWpeak or 22 µWrms has been recorded which reveals the feasibility as an alternative power source.

Owing to some advantages of high oxidation capacity, high mass-transfer efficiency, high utilisation rate of reagents, simple system for treating pollutants, micro–nanobubble technology (MNBT) has gradually attracted attention and has been successfully applied in environmental pollution control. Currently, its applications in this field are mainly in the aspects of surface water purification, sewage (waste) water treatment, soil and groundwater remediation and sludge treatment which are reviewed. These studies primarily focus on the MNB generation (MNBG) methods, the parameters of pollution treatment and its effect improvement, the coupling techniques of this technology and other advanced oxidation technologies. However, in order to successfully promote its applications to the actual environmental pollution control process, especially the industrial scale, the following efforts are required: covariant response mechanism of water quality – micro–nano aeration parameters – bubble characteristics, further optimisation of synergistic process with other advanced oxidation methods, development of lower energy consumption and more efficient MNBG devices. After discussion and analysis, this work further points out that the purification of exhaust gas such as volatile organic compounds (VOC) and flue gas is one of the research directions worth exploring in the future application of the MNBT.

Microcantilever beams were fabricated through a microelectromechanical system fabrication process; this process was improved by using etched slots. The actual mechanical properties of the cantilever beams can be estimated using a nanoindenter. Various cantilever beam widths and length-to-width ratios were used for evaluation. Five structures of cantilever beams were fabricated and compared. ANSYS software was used to simulate cantilever beam deflections. The etched slots increased the cantilever beam deflections, and the increase in deflection was apparent when the etched slot was located near the base of the beams. Type 4 was a cantilever beam with an etched slot of length L/2 near the base of the beam. The area of the etched slots of type 4 was larger, and the etched slot of type 4 was near the base of the cantilever beam. Type 4 had the shortest etching time, highest fabrication success rate, and greatest deflection. The difference between the measured and simulated (without parameter modification) deflections could exceed 10%. Modifying the force acting point and Young's modulus in the simulations reduced the difference between the measured and simulated deflections to 0.5%. This demonstrates that actual experimental conditions considerably influence simulation results, and this can be beneficial to subsequent studies.

Platinum–tin (Pt–Sn) nanoalloy catalyst supported on Al₂O₃ was prepared by carbonylation–impregnation method. The catalyst was characterised by means of nitrogen adsorption–desorption, X-ray diffraction and transmission electron microscope, showing the existence of Pt and Sn as Pt₃Sn alloy. The analysis of particle size distribution revealed that Pt–Sn nanoparticles have high dispersion and narrow particle size distribution with an average diameter of 1.7 ± 0.4 nm. Its catalytic performance toward propane dehydrogenation was also investigated. The propane dehydrogenation reaction showed that the as-prepared Pt–Sn/Al₂O₃ catalyst exhibited good dehydrogenation performance with the conversion of 27.1% and propylene selectivity of 93.3% after reacting 12 h owing to the close interaction between Pt and Sn components. Coke deposition of the used catalyst was characterised by thermogravimetric and differential thermal analysis method, revealing most of the carbon was on the surface of the support, which meant that more active sites to be accessible to maintain catalytic stability.

In the present years, nanobiotechnology has to turn out to be an important division of research. Here, this work reported a novel Mikania micrantha leaf extract-mediated silver nanoparticle (AgNP) under room temperature condition. The biosynthesised AgNPs were further characterised by various analysis techniques such as ultraviolet–visible spectrophotometer, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and transmission electron microscope (TEM) energy-dispersive X-ray spectroscopy. The formation of AgNPs was confirmed by XRD spectrum which displayed intense peaks corresponding to the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) lattice planes of Ag. The plant extracts stirred with Ag nitrate solution gradually changes its colour from light yellow to dark brown. The biogenic AgNPs were mostly spherical in shape with varying sizes ranging from 5 to 20 nm, as evident by TEM analysis. FT-IR spectra of the extract revealed the presence of amide I and amide II bonds of the proteins. The synthesised AgNPs showed excellent activity results against various Gram-positive and Gram-negative bacterial strains.

Hierarchical copper oxide (CuO) microspheres were prepared by a simple microwave-assisted preparation method in an ordinary household microwave oven under ambient pressure. The CuO microspheres were characterised by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermal gravimetric analysis. Characterisation results show that the hierarchical CuO microspheres are assembled by spine-like nanorods and have high Brunauer–Emmett–Teller surface area of 25.0 m²/g.

The conduction mechanisms in metal–insulator–metal junctions where the insulator consists of a self-assembled monolayer are investigated. Temperature dependence measurements from 2.5 to 300 K, show that the conduction is dominated by tunnelling only for temperatures below 20 K, while at higher temperatures surface-limited and bulk-limited mechanisms are observed. The experimental results are explained using a combination of direct (Simmons) tunnelling, Schottky emission, and Poole–Frenkel theory. Further insight is gained through numerical simulations based on the non-equilibrium Green-function formalism.

Novel urchin-like nickel microstructures were prepared at 150°C via a facile hydrothermal method. Such urchin-like particle is constructed by a spherical core and many spear-shaped branches with length of 200–300 nm radiated from the centre. The synthetic process involved the chemical reduction of nickel ions by hydrazine hydrate and the oriented growth of nickel nanostructures under kinetic control independent of surfactant or external magnetic field. The magnetic properties were investigated at room temperature and the results demonstrated that the sample presented ferromagnetic properties with saturation magnetisation and coercivity values of ca. 44.6 emu/g and 257.7 Oe, respectively. These urchin-like nickel microstructures are expected to bring new opportunities in application of magnetic storage and catalysis.

Fabrication and characterisation of a new methane sensor based on carbon nanotubes (CNTs) is proposed. The sensor uses low-cost SnO₂ nanoparticles and it can detect 0.5% of methane at room temperature. SnO₂ nanoparticles were deposited by electron beam deposition. The crystallography of CNT and SnO₂ was investigated by X-ray diffraction analysis. The presence of SnO₂ nanoparticles on CNTs was confirmed by scanning electron microscope images. The study’s room temperature sensor is applicable in explosive environments like refineries. Furthermore, it is easily reversible (i.e. it can return to its initial state) in air at room temperature. Low power consumption and high sensitivity are also the other advantages of this sensor. Finally, a charge transfer mechanism is proposed to describe the sensing behaviour.

Thermochromic VO₂(M) has attracted increasing attention regarding the reduction of its thermal hysteresis width (ΔT _c). However, little attention is paid to increase its ΔT _c, which may have scientific importance and potential application in the future. Herein, VO₂(M) hollow spheres assembled by nanoparticles are successfully synthesised using NH₄VO₃ as the vanadium source by a template-free method. Their diameters mainly range from 350 to 650 nm and thickness of shells is about 50 nm in average. The hydrothermal process plays a crucial role in the successful formation of VO₂(M) hollow spheres. The phase transition temperature (T _c) of VO₂(M) hollow spheres is about 63°C in the heating curve and 32°C in the cooling curve. The ΔT _c of VO₂(M) hollow spheres reach as high as 31°C, which is distinctively higher than the reported values (ca. 5–20°C). The huge ΔT _c may have potential applications in some fields in the future.