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Improving the detection limit of surface-enhanced Raman scattering (SERS) is a significant issue for the design and preparation of plasmon substrate. It always suffers from the weak absorption affinity of probe molecules on nanoscale surface, uncontrollable aggregation behaviors of nanoparticles and strong fluorescence of detected substance. In this paper, AgNPs/SiO2 substrate is prepared by rapid thermal annealing method with mean size of 87.9 ± 30.7 nm. A layer of 5–30 nm PVA (polyvinyl alcohol) film is used as the stabilizer of AgNPs. With PVA coating, AgNPs can improve the detection limit of gentian violet by three magnitudes, compared with that on undecorated AgNPs which is just 10− 5 mol/L. In the sensitive detection of coated AgNPs/SiO2 substrate, PVA possibly play three significant roles, absorption increaser between gentian violet and silver nanoparticles, fluorescence inhibiter of gentian violet and stabilizer of Ag nanoparticles. The results provide a modification method for improving SERS sensitivity of plasmon substrate, which use convenient and low-cost rapid thermal annealing as the patterning method and PVA as the coater, an advantageous technology for plasmon substrate application into trace detection.

Carbon dioxide (CO2) emissions have been steadily increasing since the beginning of human civilization. The greenhouse effect and climate change aroused by the cumulative CO2 are severely impacting the global sustainable development and pose serious concerns for our future life. Strategies toward reducing the CO2 level encompass a series of processes of carbon capture, storage, utilization, and conversion; among them the conversion of CO2 to fuels and valuable chemicals is appealing toward the development of new sustainable technologies. As the highest oxidized form of carbon, CO2 is thermodynamically stable. The breaking of its strong C=O double bonds is an endergonic process, which requires highly active and expensive catalysts for activation at ambient temperatures. Therefore, conversion of CO2 with high-temperature electrolysis technologies represents a promising strategy, which is garnering increasing attention. In this study, we present a solid oxide electrolysis cell (SOECs) design for high-efficiency CO2 conversion. The fuel electrode in an SOEC is a critical component where CO2 reduction occurs. Therefore, we focus on the design and optimization of the fuel electrode from the perspectives of chemistry (composition) and architecture (especially the thickness) to enhance the efficiency of CO2 electrolysis. A Ni-based cermet layer was developed as an ideal CO2/CO fuel electrode, based on which the cell architecture was strategically optimized with prototype Ni-YSZ/YSZ/GDC/LSCF cells (YSZ: yttria-stabilized zirconia; GDC: gadolinium-doped ceria; LSCF: lanthanum strontium cobalt ferrite). Over the course of optimization, the Ni-YSZ cermet fuel electrode was methodologically fabricated with various thickness and the cells were operated at contracting temperatures. Meanwhile, the fuel was managed with different ratios of CO2 to CO and the O2 was supplied with different flow rates at the opposite electrode. At an exemplarily optimized condition, a high electrolysis current of 1.33 A cm-2 was achieved at 750 oC with a fuel comprising of 99% CO2 and 1% CO. To assist the cell optimization, electrochemical impedance spectroscopy (EIS) was particularly used to investigate the electrochemical properties of SOECs. Meanwhile, cell components were analyzed with scanning electron microscope (SEM) before and after the electrolysis operation to study the degradation behavior of SOECs that were operated under high-current electrolysis. The detailed cell design and experimental results will be comprehensively demonstrated and presented.

Water splitting with solid oxide electrolysis cells (SOECs) has gained increasing attention as an efficient, affordable, and sustainable technology for hydrogen production. Since electricity represents the bulk of projected hydrogen cost for operating SOECs, enhancing the utilization efficiency of electricity (electrochemical energy efficiency) is critical to reach the cost-effective milestone for cell/electrolyzer development. In this study, we present a SOEC design with an ultra-thin solid electrolyte (based on an yttria-stabilized zirconia material) layer as well as an electrode support layer with reduced thickness to minimize the cell resistance. The thin electrolyte and electrode-support layers were fabricated with our optimized tape casting process. In addition to reducing the cell resistance, the implementation of thin electrolyte and electrode-support layers offers a facile and short path for gas diffusion, which can reduce the efficiency loss caused by diffusion. With our optimized cell configuration design, a high electrolysis current density was achieved at 750 oC. Over the process of cell-configuration optimization, electrochemical impedance spectroscopy (EIS) and microscopic analysis were systematically performed on the cell and cell components to rationalize the cell architecture toward accessing high electrochemical performance and high energy efficiency of the SOEC. The relevant analysis strategies and results will be presented as well.

Two-dimensional (2D) nanostructures are attractive candidates for electrocatalytic applications owing to their excellent mechanical flexibility and large exposed surfaces. In this work, we present ultra-thin 2D NiO porous nanosheets prepared by a simple, economical and green experimental method (hydrothermal, freeze-drying, and sintering) as efficient electrocatalysts for direct methanol fuel cell (DMFC) application. Benefiting from the ultra-thin 2D framework and porous nanostructure, the 550-NiO catalyst (annealed at 550 °C) exhibit higher current density (12.54mA cm−2) and faster charge transfer in the catalytic process, due to its abundant solid state redox couples (Ni2+/Ni3+= 0.991), suitable oxygen defects and surface coverage of redox species (2.90 × 10−7mol cm−2). First-principles density functional theory calculations were employed to provide mechanistic insights into the methanol oxidation reaction over the NiO catalyst via methanol dehydrogenation to CO involving O–H and C–H bond scissions, and subsequently, CHO oxidation with OH. The most plausible reaction pathway of methanol oxidation on NiO (100) is predicted to be CH3OH → CH3O → CH2O → CHO → CHOOH → COOH → CO2. The reported facile, simple, low-cost and method provides an avenue for the rational design and synthesis of 2D NiO porous nanostructured electrode materials for DMFC and beyond.

In this paper, we report a hierarchical structure Ni(OH) 2 nanosheet array electrode by a directed liquid-phase approach, which consists of amorphous Ni(OH) 2 interface layer and crystalline ultra-thin porous Ni(OH) 2 nanosheets top layer. The testing results present that the maximum discharge capacity of 404.8 mA h g −1 at lower rate of 1.4 A g −1 and the ultra-high capacity of 1714 F g −1 at super-high rate of 50 A g −1 without decay after 3000 cycles was obtained, respectively. This unique design provides excellent flexibility, long and stable cycle lifetimes, high energy and power densities simultaneously.

Synroc is recognized as the second generation waste form for the disposal of high-level radioactive waste (HLW). In this research, one of the mostly studied Synroc minerals, zirconolite (CaZrTi2O7), was prepared by self-propagating high-temperature synthesis (SHS). CuO and MoO3 were employed as the oxidants with Ti as the reductant. Different TiO2/Ti ratios were selected to investigate reactivity and adiabatic temperature (Tad) of the designed SHS reactions. Zirconolite was successfully synthesized as the main phase at varied TiO2/Ti ratios using CuO and MoO3 as the oxidants. The as-synthesized samples were readily solidified with desirable density and Vickers hardness.

A powder of oxyfluorotitanate Na3TiOF5crystals is acquired as an intermediate product during the synthesis of anatase titanium dioxide (TiO2) nanosheets with a large percentage of exposed reactive {001} facets. By application of transmission electron microscopy techniques, mainly energy dispersive spectroscopy and selected-area electron diffraction, coherent domain variants of Na3TiOF5are shown to possess monoclinic structure with space groupP21/n. The occurrence of these orientation domain variants is attributed to the reduction of crystal symmetry as a result of the phase transition from the high-temperature cubic phase to the low-temperature monoclinic phase. Through a detailed group theory analysis, the orientation domains are shown to exhibit 12 variants and 11 domain boundaries, which can be categorized into three types of perpendicular twins and two types of antiparallel twins. This work may provide meaningful insight for understanding the growth mechanism of anatase TiO2with a high percentage of reactive facets.

High yield of β-Ni(OH)2 was synthesized by hydrothermal reaction. After heat treatment, novel NiO nanosheets with hexagonal nanopores were obtained. Transmission electron microscopy was employed to investigate the morphology and the crystallographic structure of the products, which indicated that the nanosheets were commonly ⟨111⟩ orientated and the nanopores were bounded by {111} and {100} planes. Meanwhile, the nanosheets were oxygen-sufficient based on the electron energy loss spectroscopy. The mechanism associated with formation of the hexagonal nanopores was discussed according to structural evolution. This unique morphology and the chemical characteristics were considered as the probable key factor responsible for its excellent performance on catalysis, gas sense, and adsorption.

Electrogenerated chemiluminescence (ECL) of a novel phenyleneethynylene derivatives [4,4’-(2,5-dimethoxy-1,4-phenylene)bis(ethyne-2,1-diyl) dibenzoic acid; P-acid] possessing carboxylic acid groups at the para positions in aqueous solutions and its first immunosensing application are studied. Nanotubular mesoporous Pt–Ag alloy nanoparticles are first used to fabricate the ECL immunosensor as a signal amplification carrier. Absorption, photoluminescence, cyclic voltammetry, scanning electron microscopy, transmission electron microscopy, and electrochemical impedance spectroscopy are used as powerful tools to characterize P-acid, Pt–Ag alloy nanoparticles, and the fabrication process of the immunosensor. P-acid exhibits two ECL peaks at –1.07 (ECL-1) and 0.64 (ECL-2) V in air-saturated pH 7.4, 0.1 M PBS containing 0.1 M KCl during the cyclic sweep between 1.51 and –2.67 V at 0.1 V s−1; the ECL mechanism of these two ECL peaks is demonstrated. The electron-transfer reaction between electrochemically oxidized P-acid and tri-n-propylamine (TPrA) radical cation is also demonstrated to produce high ECL emissions and used to develop an ultrasensitive ECL immunosensor. In addition, a Pt–Ag alloy nanoparticles amplification carrier for protein ECL analysis is applied for improvement of the detection sensitivity. Thus, this ECL immunosensor exhibits high sensitivity, good reproducibility, rapid response, and long-term stability.

A large clearance TiO{sub 2} nanotube arrays (LTAs) has been synthesized by a not more than 12 h anodization duration and based on this a branched TiO{sub 2} nanotube arrays (BLTs) has been achieved through TiO{sub 2} nanorods branch-like grown on the LTAs. Some key factors and probable mechanisms of the fabrication processes on two novel nanoarchitectures are discussed. Exhilaratingly, it is found that the obtained LTAs has demonstrated large pore diameter and void spaces (pore diameter {approx}350 nm; void spaces {approx}160 nm; and tube length {approx}3.5 {mu}m), and the synthesized hierarchical BLTs, compared with conventional TiO{sub 2} nanotube arrays, has shown a much stronger dye absorption performance and an approximately double of the solar cell efficiency (in our case from 1.62% to 3.18% under simulated AM 1.5 conditions). - Graphical Abstract: The schematic diagram of synthesis process for LTAs and BLTs is on the above and the corresponding FESEM images of obtained photoanodes samples are shown below. Highlights: > Large clearance TiO{sub 2} nanotube arrays (LTAs) was synthesized by a fast anodization process of 12 h. > Anodization time of 12 h is just 10% of about 120 h reported in the previous references. > Branch-like TiO{sub 2} nanotubemore » arrays (BLTs) was achieved by growing TiO{sub 2} nanorods on the LTAs. > Obtained BLTs and LTAs show impressive morphology and noticeable improvement of surface area. > BLTs shows about more than 1 times higher solar cell efficiency than that of TiO{sub 2} nanotube arrays.« less

One-dimensional SrSn(OH) 6 nanowires were successfully synthesized through a rapid simple method-sonochemical synthesis at room temperature without using any templates or surfactants. The growth mechanism has been proposed, and the reaction conditions were carefully investigated. The experimental results revealed that both the ultrasound irradiation and the presence of Na 2 CO 3 in the synthetic process had an impact on the fast formation of the SrSn(OH) 6 nanowires. Moreover, a subsequent precipitation-hydrothermal treatment of SrSn(OH) 6 nanowires-was conducted in ethanol at 180 °C for 8 h in order to improve their crystallinity and thermal stalibity. SrSnO 3 nanorods were converted by calcination of the hydrothermally treated SrSn(OH) 6 nanowires at 700 °C for 3 h in air. In particular, it was the first attempt to test the electrochemical properties of the SrSnO 3 products as anode in a Li ion battery. The resulting SrSnO 3 nanorods exhibited a better cyclability over 50 cycles with a reversible lithium storage capacity of 200 mA h g ―1 than that of SrSnO 3 nanoparticles.

CaSn(OH)(6) nanotubes were fabricated by sonochemical precipitation method at room temperature. A direct rolling process from nanosheets to nanotubes was expected for the synthesis of CaSn(OH)(6) nanotubes. The transient CaSn(OH)(6) nanosheets are formed as intermediates produced by the spontaneous self-assembly and transformation of amorphous colloid clusters. During the crystallization process of intermediate nanosheets, the relaxation of surface strain in the nanosheet interfaces can induce the nanosheets to roll up to form nanotubes under ultrasonic conditions. In this synthesis, the addition of Na(2)CO(3) seems to play an important role in the formation, size, and shape control of the nanotubes. Investigations into the stability performance of the nanotubes indicate that the morphologies are very sensitive to pH and temperature. The method suggests a general strategy for the design and fabrication of functional single-crystalline nanotubes through an intermediate nanosheet rolling process. The in vitro fabrication of such single crystal nanotubes could shed light on fundamental mechanisms for closed hollow nanostructures. Furthermore, nanotubes produced in high yield and at low cost are envisioned to have applications in areas ranging from medicine to pharmaceuticals through to materials science.

Uniform crystalline MgSn(OH) 6 nanocubes were synthesized by a hydrothermal method. The influences of reaction conditions were investigated and the results showed that the solvent constituents significantly affected the shape and size of MgSn(OH) 6 ·SnO 2 /Mg 2 SnO 4 has been obtained by thermal treatment at 850 °C for 8 h under a nitrogen atmosphere using MgSn(OH) 6 as the precursor. The electrochemical tests of SnO 2 /Mg 2 SnO 4 revealed that SnO 2 /Mg 2 SnO 4 has a higher capacity and better cyclability compared to pure SnO 2 or Mg 2 SnO 4 . The electrochemical performance of SnO 2 /Mg 2 SnO 4 was sensitive to the size of the nanoparticles. The lithium-driven structural and morphological changes of the electrode after cycling were also studied by the ex-situ XRD pattern and TEM tests. This work indicates that SnO 2 /Mg 2 SnO 4 is a promising anode material candidate for application in Li-ion batteries.

Nickel hydroxyl sulfate (Ni(SO4)0.3(OH)1.4) nanobelts were obtained via a simple template-free hydrothermal reaction. The structural evolution of Ni(SO4)0.3(OH)1.4 nanobelts during ex situ heat treatment and in situ electron irradiation are investigated using transmission electron microscopy (TEM) techniques mainly including bright-field imaging, selected-area electron diffraction combined with kinematic simulations, and high-resolution TEM. The transformation from Ni(SO4)0.3(OH)1.4 to NiO can be observed in both ex situ and in situ experiments. Based on the TEM results, the structural evolution is clarified and the preliminary structural framework of Ni(SO4)0.3(OH)1.4 is proposed. This structural evolution also provides an excellent approach for large-scale production and/or modification of NiO nanoparticles.

Low-dimensional single-crystalline CdCO3 nanostructures such as nanowires, nanobelts, nanorolls, and one-dimensional (1D) hierarchical structures have been synthesized through a convenient, low-temperature hydrothermal method, and the products have been characterized by X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, and selected area electronic diffraction. The influences of ammonia concentration, reaction time, and temperature on the morphologies of CdCO3 have been investigated. In addition, these low-dimensional nanostructures can be transformed into oriented CdO nanoporous structures through heat treatment processing, and the corresponding shapes can be preserved completely.

An axial magnetic field of 0.1 T was applied to ZrF4–BaF2–LaF3–AlF3NaF fibers during heating to the glass crystallization temperature. Scanning electron microscopy and x-ray diffraction were used to identify crystal phases. It was shown that fibers exposed to the magnetic field did not crystallize, while fibers not exposed to the field did crystallize. A hypothesis based on magnetic work was proposed to explain the results, and was tested by measuring the magnetic susceptibilities of the glass and crystal.

In this paper, large-scale, single-crystalline ZnO nanotube arrays were directly fabricated onto F-doped SnO2 (TCO) glass substrate via an electrochemical deposition method from an aqueous solution for the first time. The tubes had a preferential orientation along the [0001] direction and hexagon-shaped cross sections. The novel nanostructure could be easily fabricated without a prepared layer of seeds on the substrate. The surface condition of substrate material and the experimental conditions played a key role in the nanotube formation. A possible formation mechanism has been proposed. Keywords: ZnO nanotube, Arrays, TCO glass, Electrochemical deposition

This chapter reviews the specific benchmark literature about the concepts of competence, competency model, occupational competence, competence at work and explores their logic relationship to one another. Based on this work, conceptual comparisons of competency and competence, competency model and competence model are presented. The comparative research clarifies some confusion surrounding the two pairs of concepts and emphasizes differences in their core connotations. Thus, the paper proposes that the two pairs of concepts should be distinguished in both narrow and broad senses, rather than being used alternately without distinction. We argue that the proposed distinction would be useful in establishing a coherent terminology, rather than a single terminology, e.g., competency.

Nanobelts of nickel hydroxyl sulfate have been prepared on a large scale via a simple template-free hydrothermal reaction on the basis of a complex [Ni(NH(3))(6)](2+) formed with Ni(2+) and ammonia in an ethanol-water solution. The as-synthesized nanobelts were single crystals, with several tens of microns in length and 50-150 nm in width. The nanobelts were enclosed by top surfaces (100) and side surfaces (001) and their growth direction was parallel to [010]. The function of aqueous ammonia and ethanol was discussed. Furthermore, nanostructures of a mixture of crystralline NiO and amorphous nickel sulfate with various morphologies, such as nanobelts, porous nanobelts, and nanoparticles, were obtained by the thermal treatment of the as-synthesized Ni(SO(4))(0.3)(OH)(1.4) nanobelts at different temperatures.

One-dimensional SrSn(OH) 6 nanowires were successfully synthesized through a rapid simple methods sonochemical synthesis at room temperature without using any templates or surfactants. The growth mechanism has been proposed, and the reaction conditions were carefully investigated. The experimental results revealed that both the ultrasound irradiation and the presence of Na 2 CO 3 in the synthetic process had an impact on the fast formation of the SrSn(OH) 6 nanowires. Moreover, a subsequent precipitations hydrothermal treatment of SrSn(OH) 6 nanowiresswas conducted in ethanol at 180 °C for 8 h in order to improve their crystallinity and thermal stalibity. SrSnO 3 nanorods were converted by calcination of the hydrothermally treated SrSn(OH) 6 nanowires at 700°C for 3 h in air. In particular, it was the attempt to test the electrochemical properties of the SrSnO 3 products as anode in a Li ion battery. The resulting SrSnO 3 nanorods exhibited a better cyclability over 50 cycles with a reversible lithium storage capacity of 200 mA h g−1 than that of SrSnO 3 nanoparticles.

This paper describes a facile solvothermal method to synthesize self-assembled three-dimensional (3D) Ni2+-Fe3+ layered double hydroxides (LDHs) nanocrystals. Flower-like Ni2+-Fe3+ LDHs constructed of thin nanopetals were obtained using ethylene glycol (EG) as a chelating reagent and urea as a hydrolysis agent. The reaction mechanism and self-assembly process are discussed. After calcinating the as-prepared LDHs at 450 °C in nitrogen gas, porous NiO/NiFe 2 O 4 nanosheets were obtained. This work resulted in the development of a simple, cheap, and effective route for the fabrication of large area Ni2+-Fe3+ LDHs as well as porous NiO/NiFe 2 O 4 nanosheets.

In this paper, single-crystalline Ni(SO4)0.3(OH)1.4 nanocrystals could be synthesized on a large scale by a facile hydrothermal treatment without using templates or organic additives. Ammonia concentration played an important role for the composition, phase structure and shape control of the the Ni(SO4)0.3(OH)1.4 nanobelts. Electrochemical measurement revealed that the asprepared Ni(SO4)0.3(OH)1.4 nanobelts exhibited high specific capacity close to the theoretical capacity performance of β-Ni(OH)2. On the other hand, the single-crystalline porous nickel oxide nanobeltsnanobelts can be obtained through calcination of the Ni(SO4)0.3(OH)1.4. nanobelts.

Chemically synthesized FePt nanoparticles were coated with nonmagnetic SiO2 and MnO shells by sol-gel and polyol processes. TEM images show that the FePt/SiO2 nanoparticles exhibit a thick spherical shell. The size and morphology of the MnO shell can be controlled by changing the reaction temperature, the molar ratio of surfactants/Mn(acac)2, and/or the concentration of precursor. The morphology of the MnO shell can be either spherical-like or cubic-like, depending on whether the molar ratio of surfactants/Mn(acac)2 is less than or larger than 2. From XRD measurements, the spherical core/shell nanoparticles exhibit 3D random crystallographic orientation, while the cubic core/shell nanoparticles prefer (200) texture. The magnetic moment of FePt particles can be enhanced by coating with SiO2 and MnO shells. Furthermore, the agglomeration of FePt particles upon the thermal annealing can be significantly inhibited with SiO2 and MnO shells.

Uniform crystalline CdSnO3.3H2O nanocubes with a 28-35 nm edge length have been obtained via the ion-exchange reaction of Na2Sn(OH)6 in a CdSO4 aqueous solution, assisted by ultrasonic treatment. Precursor Na2Sn(OH)6 crystals were prepared via hydrothermal treatment in an ethanol/water solution. The formation of CdSnO3.3H2O nanocubes resulted from the strain during the ion-exchange process. The influences of reaction conditions, such as ion-exchange (ultrasonic treatment) duration, solvent constitutes, surfactant, and pH on the formation of CdSnO3.3H2O crystals were described. Crystalline CdSnO3 and Cd2SnO4 have been obtained by thermal treatment at 300 and 500 degrees C, respectively, for 5 h under an inert-gas protecting condition using CdSnO3.3H2O nanocubes as the precursor. The cube shape of CdSnO3.3H2O was sustained after thermal decomposition to CdSnO3.

This paper describes a facile solvothermal method to synthesize self-assembled three-dimensional (3D) Ni2+-Fe3+ layered double hydroxides (LDHs). Flower-like Ni2+-Fe3+ LDHs constructed of thin nanopetals were obtained using ethylene glycol (EG) as a chelating reagent and urea as a hydrolysis agent. The reaction mechanism and self-assembly process are discussed. After calcinating the as-prepared LDHs at 450 degrees C in nitrogen gas, porous NiO/NiFe2O4 nanosheets were obtained. This work resulted in the development of a simple, cheap, and effective route for the fabrication of large area Ni2+-Fe3+ LDHs as well as porous NiO/NiFe2O4 nanosheets.