The development of metal deposition processes based on electroless nickel, alloy and composite coatings on various surfaces has witnessed a surge in interest among researchers, with many recent ...applications made possible from many excellent properties. In recent years, these coatings have shown promising corrosion and wear resistance properties and large number of newer developments became most important from macro to nano level applications. After a brief review of the fundamental aspects underlying the coating processes, this paper discusses in detail about different electroless nickel alloy, composite, nano plating, bath techniques, preparation, characterization, new depositing mechanism and their recent applications, including brief notes on difficult substrate and waste treatment for green environment. Emphasis will be onto their recent progress, which will be discussed in detail and critically reviewed.
One-dimensional (1D) hierarchical structures composed of nickel sulfides/MoS2 (NMS) supported on carbon nanotube (CNT) are fabricated through a one-step facile glucose-assisted hydrothermal method ...(NMS/CNT). The curled and tangled 1D structure is intertwined with each other and constructs three-dimensional (3D) porous networks, providing easy access of electrolyte. Meanwhile, the formation of metallic 1T-2H hybridized MoS2 and the synergistic effect between the MoS2 layers and nickel sulfides (NS) nanoparticles promotes the ions diffusion on the surface of the electrode, and the void space formed between NMS sheets can endure volume change in redox process for more stable structures. Therefore, the assembled NMS/CNT//activated carbon (AC) asymmetric supercapacitor manifests favorable specific capacitance of 108 F g−1 at 0.5 A g−1, along with a high energy density of 40 Wh kg−1 and good cycling stability of almost 100% capacity maintained after 10,000 cycles, implying it's the promising candidate for energy storage.
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•Hierarchical nickel sulfides/MoS2 (NMS) nanosheet supported on CNT was fabricated.•NMS/CNT//AC asymmetric supercapacitor delivers high energy density of 40 Wh kg−1.•The asymmetric supercapacitor shows excellent cycle stability for 10,000 cycles.
A facile hydrothermal method combined with a mild ultrasonic means has been developed for the fabrication of a magnetically recyclable thin-layer MnO2 nanosheet-coated Fe3O4 nanocomposite. The ...photocatalytic studies suggest that the MnO2/Fe3O4 nanocomposite shows excellent photocatalytic efficiency and stability simultaneously for the degradation of methylene blue under UV–vis light irradiation. Moreover, its good acid resistance and stable recyclability are very important for its future practical application as a photocatalyst. Magnetic measurements verify that the MnO2/Fe3O4 nanocomposite possesses a ferromagnetic nature, which can be effectively separated for reuse by simply applying an external magnetic field after the photocatalytic reaction. This novel composite material may have potential applications in water treatment, degradation of dye pollutants, and environmental cleaning.
A novel NiO/Ni/RGO three-dimensional core-shell architecture consisting of Ni nanoparticles as core, NiO as shell and reduced graphene oxide (RGO) as conductivity layer, has been constructed by redox ...reactions with hydrothermal method and heat treatment. High density arrayed nickel nanoparticles (20 nm diameter) semi-coated by a 3 nm thick layer of NiO are evenly distributed on the surface of graphene. This elaborate design not only uses abundant NiO surfaces to provide a wealth of active sites, but also bridges electrochemical active NiO shell and graphene by Ni core to construct an interconnected 3D conductive network. Since both electrochemical activity and excellent conductivity are reserved in this Ni/NiO core-shell/graphene layer 3D structure, the as-prepared electrode material exhibits an extremely high specific capacitance (2048.3 F g
at current density of 1 A g
) and excellent cycle stability (77.8% capacitance retention after 10000 cycles at current density of 50 A g
). The novel method presented here is easy and effective and would provide reference for the preparation of other high performance supercapacitor electrodes.
Transparent aluminum-doped zinc oxide (AZO) thin films were deposited on quartz glass substrates by pulsed laser deposition (PLD) from ablating Zn-Al metallic targets. The structural, electrical and ...optical properties of these films were characterized as a function of Al concentration (0-8wt.%) in the target. Films were deposited at a low substrate temperature of 150 deg C under 11Pa of oxygen pressure. It was observed that 2wt.% of Al in the target (or 1.37wt.% of Al doped in the AZO film) is the optimum concentration to achieve the minimum film resistivity and strong ultraviolet emission. The presence of Al in the ZnO film changes the carrier concentration and the intrinsic defects.
The creep behavior of nanocrystalline Cu with an average grain size of 25 nm was investigated by nanoindentation test at room temperature. Using the creep strain rate versus creep stress data ...obtained at different loading rates, the activation volume and strain rate sensitivity were determined obtained by cooperating the continuous stiffness measurement (CSM) technique. The results showed that the activation volume first increases and then decreases, and the strain rate sensitivity first decreases and then increases with increasing the creep stress. The experimental activation volume and strain rate sensitivity versus the creep stress data exhibit very good agreements with the theoretical values calculated by the previous models, respectively. The analysis based on the data of the activation volume and strain rate sensitivity revealed that at lower stress, the grain boundary activities dominate and lead to the lower creep strain rates; at higher stress, the dislocation activities dominate and lead to the higher creep strain rates. The analysis based on the data of the nanoindentation test also revealed that the use of the CSM technique can lead to the continuous creep strain rate versus creep stress data, which allows us to uncover the creep mechanisms over a wide range of the creep stress from the initial to steady stage.
It is well-known that in neutral and acidic aqueous electrolytes, MoS2 monolayers can store charges by adsorption of cations on to the electrode-electrolyte interface as its analog of graphene. ...Restricted by its low conductivity and the charge storage mechanism, the electrochemical performance of MoS2 monolayer supercapacitor electrode is not satisfactory. It is reported here that water bilayers absorbed on MoS2 monolayers can be involved in charge storage. One proton of each absorbed water molecule can intercalate/de-intercalate the water bilayers during charging/discharging in the alkaline aqueous electrolyte. For two water molecules are present for every Mo atom, the water bilayers can endow MoS2 monolayers an ultrahigh specific capacitance. In this paper, 1T phase MoS2 nanosheets with three monolayers were synthesized by hydrothermal reaction. It presents a specific capacitance of 1120 F g−1 at a current density of 0.5 A g−1 in KOH. As it is assembled with active carbon into a hybrid supercapacitor, the device has an energy density of 31.64 Wh kg−1 at a power density of 425 W kg−1, and gets a specific capacitance retention of 95.4% after 10,000 cycles at 2 A g−1.
A facile one-step hydrothermal reaction was employed to synthesis an integrated bifunctional composite composed by a network structure of ZnS/ZnO/Ni(OH)
nanosheets with ZnS/ZnO nanospheres in situ ...growing on Ni foam. The synergistic effect of these three substances make the composite having both improved electrochemical performances and photocatalytic activity. The ZnS/ZnO/Ni(OH)
-4mmol shows a high specific capacitance of 1173.8 F g
at 1 A g
, as well as good rate capability and relatively stable cyclability. Using as photocatalyst, the methyl orange dye in solution can be completely decomposed under ultraviolet-visible radiation in about 80 min. And the composite is easy to be repeatedly used because bulk Ni foam was used as a carrier. Such a bifunctional composite material provides a new insight for energy storage and utilization as well as the water pollution treatment.
•Synthesis of amorphous TiO2 modified ZnO nanorod films.•A thin layer of amorphous TiO2 was dispersed over the surface of nanorod.•Disordered TiO2 phase improved the optical absorption.•The samples ...showed enhanced photocatalytic activity.
Amorphous TiO2 modified ZnO nanorod films were synthesized via multi-step processes: ZnO nanorod films were prepared by a wet chemical method. Amorphous TiO2 was then anchored on the tops and sides of the nanorods through immersion in tetrabutyltitanate solution for hydrolysis. The as-prepared samples were characterized for the phase structure, chemical state and surface morphology as well as optical absorption using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and ultraviolet–visible (UV–vis) spectrophotometer. The results showed that the nanorod films were covered by amorphous TiO2 layers, and their visible light absorption ability was strengthened. The photocatalytic studies revealed that TiO2 modified films exhibited enhanced photocatalytic efficiency for decomposition of methyl orange under ultraviolet–visible excitation, which might be attributed to the increased UV–vis light absorption and the separation of the charge carrier and prolonged electron lifetime due to the interface between TiO2 and ZnO.
The recent development of transmission Kikuchi diffraction (TKD) in a scanning electron microscope enables fast, automated orientation mapping of electron transparent samples using standard electron ...backscatter diffraction (EBSD) hardware. TKD in a scanning electron microscope has significantly better spatial resolution than conventional EBSD, enabling routine characterization of nanocrystalline materials and allowing effective measurement of samples that have undergone severe plastic deformation. Combining TKD with energy dispersive X-ray spectroscopy (EDS) provides complementary chemical information, while a standard forescatter detector system below the EBSD detector can be used to generate dark field and oriented dark field images. Here we illustrate the application of this exciting new approach to a range of deformed, ultrafine grained and nanocrystalline samples, including duplex stainless steel, nanocrystalline copper and highly deformed titanium and nickel–cobalt. The results show that TKD combined with EDS is a highly effective and widely accessible tool for measuring key microstructural parameters at resolutions that are inaccessible using conventional EBSD.
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