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Electroless nickel-based depositions have been considered as one of the industrially effective methods because of their deposition uniformity, good corrosion properties, high wear resistance and good electrical properties. In this study, Ni-P-W-CNF composite depositions were performed by electroless method on an aluminum substrate from an acidic hypophosphite at different sodium tungstate and CNFs contents. The main aim of this study was to deposit Ni-P-W-CNF composites and characterization of their morphology, tribological and corrosion behaviors. The Ni-P-W-CNF composite depositions were characterized using Scanning Electron Microscopy, X-Ray Diffraction analysis and Raman spectroscopy. The tribological behaviors of the Ni-P-W-CNF composite depositions were evaluated with reciprocating ball-on-disk test in dry conditions. The corrosion resistance behavior of the Ni-P-W-CNF composite depositions carried out by means of Tafel Polarization methods in 3.5% NaCl solution. The effects of CNFs and tungsten on the tribological and corrosion behaviors of the composite depositions were discussed. It was found that the best wear and corrosion resistance has been obtained Ni-P-W-CNF electroless co-deposition containing 100 g/L Na 2 WO 4 and 0.2 g/L CNFs in the deposition bath. [ABSTRACT FROM AUTHOR]

We report the local homoepitaxial growth of NiO thin films with simultaneously tunable crystallization, preferred growth orientation, and electrical properties by reactive sputtering. Using a seed layer with 〈 100 〉 fiber texture previously deposited on glass and silicon substrates, the room temperature growth of highly 〈 100 〉‐oriented NiO thin films with good crystallization has been achieved. Microstructure analyses evidence that the columns of the top layer are homoepitaxially grown on the columns of seed one. The resistivity of 〈 100 〉‐oriented homoepitaxial layer is lower than the seed one and higher than that of single layer of multiple orientations deposited with the same condition. [ABSTRACT FROM AUTHOR]

The electronic properties of NiO (1 1 0)/MAPbI 3 (1 0 0) interface are investigated by the first-principles calculations. The NiO (1 1 0)/MAPbI 3 (1 0 0) interfacial lattice mismatch is 7.3%. The binding energy of the NiO (1 1 0)/MAPbI 3 (1 0 0) interface is −0.059 J/m 2 , and the atoms bonding is irregular at the interface. There are some interface states nearby the NiO (1 1 0)/MAPbI 3 (1 0 0) interface. Interface states of the NiO (1 1 0)/MAPbI 3 (1 0 0) interface mainly are attributed to I-5 p , O-2 p and Ni-3 d orbitals on the MAPbI 3 (1 0 0) layer1 and NiO (1 1 0) layer1. [ABSTRACT FROM AUTHOR]

Cluster−assembled Ni−NiO core−shell structures were periodically immersed into multiferroic Bi 5 Ti 3 FeO 15 (BTFO) film matrices to form pseudo 1–3 BTFO/Ni−NiO/BTFO heterostructural films with multiferroic/antiferromagnetic/ferromagnetic (MF/AFM/FM) multi−interfaces. A biased magnetoelectric coupling effect was obtained at room temperature by a magnetic annealing process. The biased direction depends on the orientation of the annealing magnetic field, with magnetoelectric coefficient curves moving to left after positive annealing magnetic field, while moving to right with negative annealing magnetic field. This biased magnetoelectric effect originates from the multi−interface spin exchange coupling. The immersion of cluster−assembled Ni−NiO core−shells in the multiferroic matrices enhance the interfacial coupling effect due to the large surface-to-volume ratio. Thus, the interfacial spin exchange induced biased magnetoelectric effect is enhanced and reversible. The work provides an avenue on the weak magnetic field detection, spintronic devices and multistate switching memories. [ABSTRACT FROM AUTHOR]

Transition metal oxides/sulfides as novel electrode materials for high-performance supercapacitors have gained much attention, but an effective fabrication method has become a bottleneck in advancing large-scale synthesis. Herein, hierarchical nickel cobalt oxides (NiCo x O y ) and flaky nickel cobalt sulfides (NiCo x S y ) have been successfully synthesized by a time-consuming chemical bath deposition method. Owing to the hierarchical architecture and high specific surface area (128.1 m 2 /g), the NiCo x O y displays a specific capacitance of 507.3 F/g at a current density of 1 A/g and excellent long-term cycling stability. Meanwhile, benefiting from the flaky mesoporous structure and high conductivity, the as-fabricated NiCo x S y can deliver high specific capacitance (1196.1 F/g at 1 A/g), acceptable cycling stability, and superior rate performance (61.7% retention from 1 to 20 A/g). All these results reveal that chemical bath deposition method is a promising route for the large-scale preparation of supercapacitors electrode materials. [ABSTRACT FROM AUTHOR]

To survey the probability of the re-utilization of nickel containing slag corroded magnesia and aluminagraphite refractories, different amounts of nickel oxide (NiO) were used as one of raw materials to synthesize nickel containing magnesium aluminum oxynitride (MgAlON) composites, and the sintering and oxidation behavior have been explored in this work. The results reveal that with the increasing NiO additive, submicron metallic Ni grains are segregated from the (Ni,Mg)AlON spinel, and these grains are beneficial to improve thermal shock resistance of MgAlON. Though the oxidation reaction of (Ni,Mg)AlON starts at lower temperature than MgAlON, the metallic Ni grains in the plate can improve the oxidation resistance. Hence, the metallic nickel containing (Ni, Mg)AlON composite has not only superior thermal shock resistance but also excellent oxidation resistance, and it is of great potential to utilize in plant. So, the fabrication of metallic nickel containing (Ni,Mg)AlON composite should be a feasible way to reuse the nickel slag corroded magnesia and alumina graphite refractories. [ABSTRACT FROM AUTHOR]

Abstract: Metal–organic frameworks (MOFs) and MOF‐derived nanostructures are recently emerging as promising catalysts for electrocatalysis applications. Herein, 2D MOFs nanosheets decorated with Fe‐MOF nanoparticles are synthesized and evaluated as the catalysts for water oxidation catalysis in alkaline medium. A dramatic enhancement of the catalytic activity is demonstrated by introduction of electrochemically inert Fe‐MOF nanoparticles onto active 2D MOFs nanosheets. In the case of active Ni‐MOF nanosheets (Ni‐MOF@Fe‐MOF), the overpotential is 265 mV to reach a current density of 10 mA cm−2 in 1 m KOH, which is lowered by ≈100 mV after hybridization due to the 2D nanosheet morphology and the synergistic effect between Ni active centers and Fe species. Similar performance improvement is also successfully demonstrated in the active NiCo‐MOF nanosheets. More importantly, the real catalytic active species in the hybrid Ni‐MOF@Fe‐MOF catalyst are unraveled. It is found that, NiO nanograins (≈5 nm) are formed in situ during oxygen evolution reaction (OER) process and act as OER active centers as well as building blocks of the porous nanosheet catalysts. These findings provide new insights into understanding MOF‐based catalysts for water oxidation catalysis, and also shed light on designing highly efficient MOF‐derived nanostructures for electrocatalysis. [ABSTRACT FROM AUTHOR]

Herein, we assessed the capabilities of NiO and Ni(OH) 2 electrodes for l -lactic acid sensing and compared the performances of the corresponding non-enzymatic sensors. Specifically, NiO and Ni(OH) 2 sensors showed high sensitivities, 9.08 and 35.76 μA/(mM cm 2 ) and low detection of limit, 0.53 and 0.59 mM, respectively. Both sensors also show good selectivity and being insensitive to interferents such as l -ascorbic acid, uric acid, and dopamine. Furthermore, electrochemical characterization at variable scan rates revealed that NiO achieves faster sensing than Ni(OH) 2 , implying that the above electrodes exhibited different sensing mechanisms. Thus, X-ray photoelectron spectroscopy analysis confirmed that the NiO electrode inherently contained Ni 3+ ions acting as active sites for lactate detection and therefore increasing the response speed, whereas Ni(OH) 2 contained no Ni 3+ and had to be electrochemically converted into NiOOH prior to analyte detection. Consequently, the NiO electrode provided faster and more reliable lactate sensing, thus exhibiting promising non-enzymatic lactate sensor. [ABSTRACT FROM AUTHOR]

Ni-based catalysts have shown promise activity towards the oxygen evolution reaction (OER). The stability and the activity of the Ni-based catalysts are crucial parameters that gained a lot of interest recently. This paper addresses the effect of the preparation temperature ( T p ) on the electrocatalytic activity of nickel oxide nanostructures modified glassy carbon (nano-NiOx/GC) electrode towards the OER. Increasing T p , beyond room temperature ( r.t. ), results in enhancing the kinetics of the OER demonstrated in the values of the exchange current density ( i o ) and the onset potentials of the OER. The effect of T p is reflected on the morphology and size of NiOx, that is increasing T p results in decreasing their particle size. Elevated T p enhances the OER as a result of increasing the population of the electroactive NiOx phases as indicated from their respective XRD patterns. Rapid degradation of the catalytic activity of nano-NiOx/GC electrode towards the OER is observed upon prolonged electrolysis at r.t. Cycling the potential several times between 0.85 and 1.65 V vs. RHE restores the activity to various extents depending on the measurement temperature ( T m ). [ABSTRACT FROM AUTHOR]

The electromagnetic interference (EMI) shielding effectiveness and the intrinsic electrical properties of polymeric material filled with two different nanostructured fillers were investigated. The polymeric material being polyvinylidene fluoride (PVDF) and nickel oxide (NiO) and barium titanate (BaTiO 3 ) were used as nanofillers. The PVDF/NiO/BaTiO 3 nanocomposite films were prepared with the variable concentration of nanofillers using solvent casting method. The structural and morphological analysis of PVDF/NiO/BaTiO 3 nanocomposite films was carried out using Fourier transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning electron microscopy (SEM). To understand the EMI shielding effectiveness, the absorption was studied in the Ku-band frequency range (8 Hz–12 Hz). The FTIR analysis shows the interaction between the phases at varying concentrations of nanofillers and the XRD analysis shows characteristic peaks of all the constituents of PVDF/NiO/BaTiO 3 nanocomposites. SEM micrographs of PVDF/NiO/BaTiO 3 nanocomposite film reveal homogeneous dispersion of both NiO and BatiO 3 in the PVDF matrix. The impact of variable concentration of nanofillers on the overall shielding effectiveness (SE) was also investigated with the shielding effectiveness of −11.5 dB. [ABSTRACT FROM AUTHOR]

Transparent oxide semiconductors hold great promise for many optoelectronic devices such as transparent electronics, UV-emitting devices, and photodetectors. A p-n heterojunction is the most ubiquitous building block to realize these devices. In this work, we report the fabrication and characterization of the interface properties of a transparent heterojunction consisting of p-type NiO and n-type perovskite BaSnO3. We show that high-quality NiO thin films can be epitaxially grown on BaSnO3 with sharp interfaces because of a small lattice mismatch (∼1.3%). The diode fabricated from this heterojunction exhibits rectifying behavior with a ratio of 500. X-ray photoelectron spectroscopy reveals a type II or “staggered” band alignment with valence and conduction band offsets of 1.44 eV and 1.86 eV, respectively. Moreover, a large upward band bending potential of 0.90 eV for BaSnO3 and a downward band bending potential of 0.15 eV for NiO were observed in the interface region. Such electronic properties have important implication for optoelectronic applications as the large built-in potential provides favorable energetics for photo-generated electron-hole separation/migration. [ABSTRACT FROM AUTHOR]

Transparent oxide semiconductors hold great promise for many optoelectronic devices such as transparent electronics, UV-emitting devices, and photodetectors. A p-n heterojunction is the most ubiquitous building block to realize these devices. In this work, we report the fabrication and characterization of the interface properties of a transparent heterojunction consisting of p-type NiO and n-type perovskite BaSnO3. We show that high-quality NiO thin films can be epitaxially grown on BaSnO3 with sharp interfaces because of a small lattice mismatch (∼1.3%). The diode fabricated from this heterojunction exhibits rectifying behavior with a ratio of 500. X-ray photoelectron spectroscopy reveals a type II or “staggered” band alignment with valence and conduction band offsets of 1.44 eV and 1.86 eV, respectively. Moreover, a large upward band bending potential of 0.90 eV for BaSnO3 and a downward band bending potential of 0.15 eV for NiO were observed in the interface region. Such electronic properties have important implication for optoelectronic applications as the large built-in potential provides favorable energetics for photo-generated electron-hole separation/migration. [ABSTRACT FROM AUTHOR]

Polymer nanocomposites of Poly (styrene co-acrylonitrile)/Nickel Oxide (PSAN/NiO) have been prepared. The increased free volume sizes up to 0.4 wt% of NiO loading indicates overall reduction in packing density of polymer network. The decreased o-Ps lifetime (τ 3 ) at higher concentration of NiO indicates improved interfacial interaction between the surface of NiO nanoparticles and side chain of PSAN polymer matrix. The increased AC/DC conductivity at lower wt% of NiO loading demonstrates increased number of electric charge carriers/mobile ions and their mobility. The increased dielectric constant and dielectric loss up to 0.4 wt% of NiO loading suggests the increased dipoles polarization. [ABSTRACT FROM AUTHOR]

Nickel cobalt oxide (NiCo 2 O 4 ) particles with a diamond-shaped hexahedral porous sheet structure are successfully synthesized by a facile hydrothermal method, followed by calcination in one step. NiCo 2 O 4 -I and NiCo 2 O 4 -II particles are prepared using the same method with different contents of urea (CO(NH 2 ) 2 ) and ammonium fluoride (NH 4 F). The different morphologies of the NiCo 2 O 4 -I and NiCo 2 O 4 -II particles illustrate that CO(NH 2 ) 2 and NH 4 F play an important role in crystal growth. To verify the influence of NH 4 F and CO(NH 2 ) 2 on the morphology of the NiCo 2 O 4 particles, the theory of crystal growth morphology is analyzed. The electrochemical measurements show that NiCo 2 O 4 particles exhibit a high specific capacitance. At a current density of 1.0 mA cm −2 , the mass specific capacitances of the NiCo 2 O 4 -I and NiCo 2 O 4 -II electrodes are 690.75 and 1710.9 F g −1 , respectively, in a 6 M KOH aqueous electrolyte. The specific capacitances of the NiCo 2 O 4 -I and NiCo 2 O 4 -II electrodes remain ∼95.95% and ∼70.58% of the initial capacitance values after 5000 cycles, respectively. According to the two-electrode test, the NiCo 2 O 4 -II//AC asymmetric electrodes exhibited an ultrahigh energy density of 64.67 Wh kg −1 at the power density of 12 kW kg -1 , demonstrating its excellent application potential as an electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

In this work, porous NiO microspheres interconnected by carbon nanotubes (NiO/CNTs) were successfully fabricated by the pyrolysis of nickel metal-organic framework precursors with CNTs and evaluated as anode materials for lithium-ion batteries (LIBs). The structures, morphologies, and electrochemical performances of the samples were characterized by X-ray diffraction, N2 adsorption-desorption, field emission scanning electron microscopy, cyclic voltammetry, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy, respectively. The results show that the introduction of CNTs can improve the lithium-ion storage performance of NiO/CNT composites. Especially, NiO/CNTs-10 exhibits the highest reversible capacity of 812 mAh g−1 at 100 mA g−1 after 100 cycles. Even cycled at 2 A g−1, it still maintains a stable capacity of 502 mAh g−1 after 300 cycles. The excellent electrochemical performance of NiO/CNT composites should be attributed to the formation of 3D conductive network structure with porous NiO microspheres linked by CNTs, which benefits the electron transfer ability and the buffering of the volume expansion during the cycling process. [ABSTRACT FROM AUTHOR]

The structural, electrical and optical property of nickel oxide thin films deposited by electron beam physical vapour deposition were investigated with respect to substrate temperature ( T s = 100, 300, and 450 °C). In spite of the amorphous nature of the substrate (quartz), depending on the substrate temperature either a preferred or polycrystalline NiO growth was observed. A (200) preferential orientation resulted at 100 °C while at 300 and 450 °C the NiO films were oriented along (111) and (220) planes. The NiO films obtained at T s = 100 °C was highly transparent compared to the polycrystalline films due to the low light scattering of (200) film. The conductivity of NiO films measured at 100 °C was found to be three orders higher than the films obtained at T s = 450 °C. Thus, the orientation was found to be influencing optical and electrical properties of NiO films. [ABSTRACT FROM AUTHOR]

Transparent p-n heterojunctions composed of p-NiO and n-ZnO thin films have been fabricated on indium-tin-oxide (ITO)-coated glass substrates at room temperature by magnetron sputtering. Various oxygen flow rates have been employed to grow the NiO thin films, yielding the tunable resistivity of NiO layers. These p-n junctions exhibit clear rectifying current-voltage characteristics. Moreover, their electrical properties can be effectively tuned by the oxygen flow rate to synthesize NiO layers in these junctions. NiO layer with closely perfect stoichiometry and quite high resistivity produces better performance in these p-n junctions, including the small threshold voltage and ideality factor, as well as high rectifying ratio. The evolution tendency of threshold voltage as a function of the resistivity of NiO is qualitatively discussed. [ABSTRACT FROM AUTHOR]

The necessity of developing Ni-rich layered oxides cathode materials with more than 90% of Ni content is rapidly increasing for satisfying the demand of achieving the high capacity of Li-ion batteries. However, including more Ni contents results in increased formation of undesirable Li residues at the surface as well as deteriorating several types of degradation behaviors during cycling, which are the critical factors of design rules for the cathode material. In this study, the facile synthesis of an electrochemically active material, LiCoO2, is realized at the surface of LiNi0.91Co0.06Mn0.03O2 via the conventional dry coating method utilizing the Li-reactive capability of Co3O4. First-principles calculations are performed to investigate the possible formation of LiCoO2 from the phase diagram. The formation of the electrochemically active coating material considerably reduces the Li residues, increases the capacity and exhibits a better cycle life with enhanced rate capability. The presence of LiCoO2 phase is verified from transmission electron microscopy (TEM) images, energy-dispersive X-ray spectroscopy (EDS) elemental mapping and electron energy loss spectroscopy (EELS) spectra. Superior performance of Co3O4 is further demonstrated by comparing the results with those from conventional coating materials of Al2O3, TiO2, V2O3 and ZnO, whose electrochemical performance is worse in all of aspects. [ABSTRACT FROM AUTHOR]

In this work, the 3D NiO-Ni/ANWs/FTO electrode for micro-supercapacitor application is fabricated by facile electrochemical deposition and post annealing process. At the optimal under annealing conditions, the composite electrodes demonstrate an excellent specific capacity up to 344 mAh g −1 at 2.5 A g −1 based on GCD result in 2 mol L −1 KOH as electrolyte. In particular, our original welding treatment by rapidly annealing process of the 3D ANWs network dramatically increases the lifetime and stability, ∼100% capacitance retention after 20000 cycles. Meanwhile, the NiO-Ni/ANWs composite own high average transmittance in visible and near infra-red regions as high as 82%, which is suitable for fully transparent electronic device application. For on-chip purpose the FTO substrate has perfect compatibility can also be easily replaced by any shape or form p/n-Si, metal, semiconductor, and any other conductive substrates. [ABSTRACT FROM AUTHOR]

The polydopamine-assisted hierarchical composites of ultrathin NiO nanosheets uniformly coating on the surface of hollow nitrogen-doped carbon spheres (HNCS-NiO) were successfully fabricated via a facile synthesis method. The hierarchical HNCS-NiO composites as electrode materials for supercapacitors exhibit high capacitance of 550.4 F g − 1 (880.6 mF cm − 2 ) at the current density of 0.5 A g − 1 (0.8 mA cm − 2 ), and present a good rate capability. The composites display excellent improved electrochemical properties not only because their hierarchical hollow nanostructures can provide enough space to buffer the volume expansion during the reversible intercalation/deintercalation processes, but also because their larger specific surface areas can provide adequate active sites for the redox electrochemical reaction. [ABSTRACT FROM AUTHOR]

Rare-earth nickelates form an intriguing series of correlated perovskite oxides. Apart from LaNiO3, they exhibit on cooling a sharp metal-insulator electronic phase transition, a concurrent structural phase transition, and a magnetic phase transition toward an unusual antiferromagnetic spin order. Appealing for various applications, full exploitation of these compounds is still hampered by the lack of global understanding of the interplay between their electronic, structural, and magnetic properties. Here we show from first-principles calculations that the metal-insulator transition of nickelates arises from the softening of an oxygen-breathing distortion, structurally triggered by oxygen-octahedra rotation motions. The origin of such a rare triggered mechanism is traced back in their electronic and magnetic properties, providing a united picture. We further develop a Landau model accounting for the metal-insulator transition evolution in terms of the rare-earth cations and rationalizing how to tune this transition by acting on oxygen rotation motions. [ABSTRACT FROM AUTHOR]

Nanoporous NiO thin films were prepared onto FTO glass substrates by means of screen-printing and were sensitized with Erythrosine B (EryB) dye. The obtained material was electrochemically treated and characterized with ex-situ X-ray photoelectron spectroscopy in order to gain information beneficial to the application of sensitized NiO as photocathodes of p -type dye-sensitized solar cells ( p -DSCs). In particular, EryB-sensitized NiO films underwent a series of electrochemical treatments in LiClO 4 /Acetonitrile (ACN) electrolyte devised so as to simulate possible conditions the electrode might encounter during operation in the photoelectrochemical cell. Upon potential-cycling in a range where the two NiO faradic events Ni(II) → Ni(III) and Ni(III) → Ni(IV) occur, X-ray photoelectron spectroscopy revealed that Erythrosine B dye experiences a partial detachment from the NiO surface. This detachment seems to be paralleled by the formation of stable (Ni) + (ClO 4 ) − couples. Overall, the EryB dye displayed an acceptable electrochemical stability onto the surface of NiO electrode up to 50 cyclic voltammetries in the range −0.27 ÷ +1.13 V vs. Ag/AgCl. These results are useful for the evaluation of electrochemical stability of the dye when this is immobilized onto an electrode surface and are beneficial for a better comprehension of the degradation phenomena operating in real photoconversion device. [ABSTRACT FROM AUTHOR]

Na-doping concentration dependent electrical and structural properties of NiO ceramics were investigated. Various samples of Na x Ni 1−x O (x = 0.00, 0.01, 0.03, 0.05, 0.07, 0.09, 0.11) were prepared by using conventional solid state reaction. Most of the samples showed the decreased electrical resistivity with the increase of the Na-doping concentration while maintaining phase-pure face-centered cubic (fcc) structure, except in the case of the sample containing 11% of Na. For the sample containing 11% of Na, the electrical resistivity slightly increased due to the presence of secondary phase. The possible physical origin of this reduced electrical resistivity is related to the increased number of oxygen vacancies, with the increase of the Na-doping concentration for phase-pure Na x Ni 1−x O ceramics. [ABSTRACT FROM AUTHOR]

Solvent engineering for the electrochemical preparation of porous, thick, and adherent nickel oxide layers is investigated. The deposition of this oxide is studied in pure aprotic dimethyl sulfoxide (DMSO) medium and in DMSO/water mixtures through the cathodic reduction of a nickel nitrate precursor. In pure DMSO, the as-grown layers were a mixture of directly obtained NiO and metallic nickel. On the other hand, in the presence of water, β-Ni(OH)2 and Ni° mixed layers were formed. In the absence of water or at low water contents, we show that the solvent is included in the layer. After annealing at a sufficient temperature to eliminate DMSO, pores are released and mesoporous films are formed. These solvent-templated electrodeposited layers have been applied in p-type dye-sensitized solar cells (p-DSSCs) after sensitization by the P1 dye. For high water content (25 vol.%), the electrodeposited layers were non-porous and were consequently unsuitable for p-DSSC application. [ABSTRACT FROM AUTHOR]

We have studied the electrical conductivity, dielectric relaxation mechanism and impedance spectroscopy characteristics of nickel oxide ( NiO ) thin films synthesized by chemical bath deposition (CBD) method. Thickness dependent structural, optical and ac electrical characterization has been carried out and deposition time was varied to control the thickness. The material has been characterized using X-ray diffraction and UV-VIS spectrophotometer. Impedance spectroscopy analysis confirmed enhancement of ac conductivity and dielectric constant for films deposited with higher deposition time. Decrease of grain size in thicker films were confirmed from XRD analysis and activation energy of the material for electrical charge hopping process was increased with thickness of the film. Decrease in band gap in thicker films were observed which could be associated with creation of additional energy levels in the band gap of the material. Cole-Cole plot shows contribution of both grain and grain boundary towards total resistance and capacitance. The overall resistance was found to decrease from ~ 14.6 × 10 5 Ω for 30 min deposited film (~ 120 nm thick) to ~ 2.42 × 10 5 Ω for 120 min deposited film (~307 nm thick). Activation energy value to electrical conduction process evaluated from conductivity data was found to decrease with thickness. Identical result was obtained from relaxation time approach suggesting hopping mechanism of charge carriers. [ABSTRACT FROM AUTHOR]

The change in porosity of the Ni-3.5YSZ (ZrO stabilized with 3.5 mol.% YO) composite, when produced, and the effect of porosity on the strength and electrical conductivity is studied. The porosity was provided by adding granular starch to the mixture of NiO and 3.5YSZ powders. The content of 18 vol.% pore-forming agent in the Ni-3.5YSZ cermet provides open porosity 47.1%, while its strength and electrical conductivity are 74.3 MPa and 0.93 · 10 S/m, respectively. [ABSTRACT FROM AUTHOR]

A multilayered NiO film is fabricated on 3D Ni foam (NF) substrate via electrochemical cyclic voltammetry (CV) as a high-efficient methanol oxidation catalyst. We carefully studied the formation mechanism of an as-fabricated electrode and found that lower cathode potential in CV plays a key role in constructing the microstructure of this material. The as-synthesized electrode shows remarkable electrocatalytic methanol oxidation activity (161.5 mA cm in 1 M KOH with 0.3 M methanol) and good stability (current retention >92% after 500 cycles) in three-electrode measurement. Moreover, the NiO film/Ni foam is further used as anode catalyst in two-electrode configured methanol-water solution electrolysis. A sharp decline of cell voltage is observed (∼170 mV) when 0.1 M methanol was added in alkaline solution. In addition, the methanol-water solution electrolysis also exhibits lower electric energy consumption (∼41.87 KWh kg @200 mA cm) for hydrogen production. [ABSTRACT FROM AUTHOR]

Nanostructured nickel oxide (NiO) electrode has been prepared using electrochemical work station operated on galvanostatic mode in supercapacitor application. Crystalline cubic structure and nanoplate-type of morphology of synthesized NiO electrode was confirmed from X-ray diffraction and scanning electron microscopy analysis respectively. The wettability study was tested by contact angle measurement, which reveals hydrophilic nature of NiO electrode with contact angle of 59°. The presence of nickel and oxygen characteristic bands in EDAX and XPS spectrum has corroborated the NiO formation. The supercapacitive properties of NiO electrode were tested by cyclic voltammogram (CV) in 1 M aqueous NaSO, KOH, NaOH electrolytes within the potential range of − 1.1 to 0.9 V, 0 to 0.4 V and − 1.2 to 0.4 respectively. The CV study demonstrates maximum specific capacitance of 481.16 Fg for 1 M NaSO. The obtained specific power, specific energy and coulombic efficiency values of NiO electrode are 19.48 kW kg, 60.12 Whkg, and 92.31%, respectively. In the meantime it exhibited excellent cycle life time with 92.3% specific capacitance kept after 1000 cycles. These results imply that NiO electrode is promising candidate for upcoming thin film supercapacitors and other microelectronic constructions. [ABSTRACT FROM AUTHOR]

This paper deals with degradation mechanisms of Ni-YSZ electrodes for solid oxide cells, mainly solid oxide electrolysis cells (SOECs), but also to some extent solid oxide fuel cells (SOFCs). Analysis of literature data reveals that several apparently different and even in one case apparently contradicting degradation phenomena are a consequence of interplay between loss of contact between the Ni-YSZ (and Ni-Ni particles) in the active fine-structured composite fuel electrode layer and migration of Ni via weakly oxidized Ni hydroxide species. A hypothesis that unravels the apparent contradiction and explains qualitatively the phenomena is presented, and as a side effect, light has been shed on a degradation phenomenon in solid oxide fuel cells (SOFCs) that has been observed during a decade. [ABSTRACT FROM AUTHOR]

Thin NiO films are deposited by reactive magnetron sputtering and spray pyrolysis. The main optical constants, i.e., refractive index n(λ), absorption coefficient α(λ), extinction coefficient k(λ), and thickness d, are determined. The temperature dependence of the resistance of thin films is found, and the activation energy of films deposited by different methods is determined. [ABSTRACT FROM AUTHOR]

Nanostructured nickel oxide (NiO) thin films were deposited on fluorine doped tin oxide (FTO) substrates by inexpensive spray pyrolysis. The influence of substrate temperature on structural, morphological and electrochemical properties has been investigated. The structural and morphological analysis showed all NiO thin films were found to be similar to the thin film synthesized by conventional methods From the electrochemical results specific capacitance of NiO thin films increased between 16 to 88 F/g with the substrate temperature. The specific energy, specific power and coulomb efficiency are found to be 8.93 Wh/kg, 0.52 KW/ kg and 85.08%, respectively. Moreover, electrochemical impedance study showed higher conductivity and excellent Warburg impedance coefficient for NiO thin film deposited at 370 °C electrode materials. [ABSTRACT FROM AUTHOR]

In this research, physical properties of nickel oxide nano-structured layers doped with various amount of Cu atoms (20-60 at.%) is studied using spray pyrolysis method on the glass substrate. The FESEM images show formations of nanostructures of about 20-60 nm and the XRD patterns show layers have a polycrystalline cubic structure nature with (111) as the preferred direction that its intensity reduces as the doping density increases. Analyzing transmittance UV. Vis spectra shows the variations of optical band gap of the samples are due to occurrence of doping atoms and quantum confined effects. Optical permittivity of different doped films have been compared using new numerical method and show the prominent effect of doping percent to real and imaginary parts of electrical permittivity. Also Hall effect results shows that Cu atoms substituted by Ni atoms sites play as acceptor atoms in the crystalline lattice. Finally, thermo-optical properties of the films have been studied using Nd-YAG laser illumination. [ABSTRACT FROM AUTHOR]

Vertically aligned Ni(OH)2 nanosheets were grown on carbon paper (CP) current collectors through a simple and cost-effective hydrothermal approach. The as-grown nanosheets are porous and highly crystallized. If used as a monolithic electrode for electrochemical water oxidation in alkaline solution, the carbon paper supported Ni(OH)2 nanosheets [CP@Ni(OH)2] exhibit high electrocatalytic activity and excellent long-term stability. The electrode can attain an anodic current density of 20 mA cm−2 at a low overpotential of 338 mV, comparable to that of state-of-the-art RuO2 nanocatalysts supported on CP (CP/RuO2) with the same catalyst loading. Significantly, CP@Ni(OH)2 shows much better long-term stability than CP/RuO2 upon continuous galvanostatic electrolysis, particularly at a high industry-relevant current density such as 100 mA cm−2. CP@Ni(OH)2 can sustain water oxidation at 100 mA cm−2 for 50 h without any degradation, whereas the performance of CP/RuO2 is much poorer and deteriorates gradually over time. CP@Ni(OH)2 electrodes hold substantial promise for use as low-costing water oxidation anodes in electrolyzers. [ABSTRACT FROM AUTHOR]

NiO with spherical-like morphology were prepared by microwave irradiation using Ni(II) acetate, water as solvent and sodium hydroxide (NaOH) as precipitator agent. Structural, optical and nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis absorption; Fourier transformed infrared (FTIR). The XRD pattern studies revealed the NiO have a face-centered cubic structure. The composition of nanostructures confirmed by analysis of FTIR spectra. The average size of the NiO nanoparticle observed from SEM images is found to be dimensions about 20 nm. [ABSTRACT FROM AUTHOR]

The preparative parameters have been optimized for NiO film formation in fabricated Spray Pyrolysis System using pneumatic air pressure driven aerosol formation. The structural studies by X-ray diffractometer (XRD) have been carried out to investigate crystallographic features. It was revealed that NiO crystallizes in cubic bunsenite structure. The optical band gap for direct transitions was found to be equal to 3.67 eV. Field Emission Scanning Electron Micrographs (FESEM) have been employed to study morphological aspects of the prepared films. The elemental depth profiles of film contents have been obtained Auger Electron Spectroscopic (AES) studies. [ABSTRACT FROM AUTHOR]

This work investigates the electrical properties of NiO–SDC/SDC anode sintered at approximately 1200°C for 1 h via the microwave method. Nanopowders Sm0.2Ce0.8O1.9(SDC—samaria-doped ceria) and NiO were mixed using a high-energy ball mill and subsequently co-pressed at three different compaction pressures of 200, 300, and 400 MPa. This study determines the effect of compaction pressure on the electrochemical performance of Ni–SDC/SDC anode, with no binder used between layers. The electrical behavior of the prepared anode was studied via electrochemical impedance spectroscopy in controlled atmospheres, operating at high temperatures (600–800°C). The results indicate that decreasing the compaction pressure and increasing the operating temperature lead to a high electrochemical performance of the nonsymmetrical NiO–SDC/SDC anode. The mechanism for manufacturing NiO–SDC/SDC involves ball milling, dry pressing, and microwave furnace sintering processes. [ABSTRACT FROM AUTHOR]

Carrier-selective contacts based on thin oxides of nickel and titanium are computationally investigated for heterojunction silicon solar cells. Replacing the standard amorphous/c-Si heterojunction with NiO/c-Si (front) and TiO2/c-Si (back), we explore the physical requirements to enhance the cell efficiency beyond the physical limits of the conventional structure. Under ideal conditions, a wider bandgap (>3 eV) of these metal oxides provides a high optical transparency, whereas a near-perfect alignment of their energy bands with silicon ensures a high fill factor (FF), which is often difficult to obtain in some of the other wide-bandgap alternatives, e.g., SiOx, due to imperfect band offsets that hinder carrier extraction. We explore the practical nonidealities that could possibly degrade cell efficiency below its ideal limit. In particular, effects of interfacial defects, Fermi-level pinning at c-Si/TiO2/metal contact, variability in the bandgap of NiO, and nonoptimized metal oxide doping density are investigated quantitatively. Using the reported experimental data for these nonideal effects, we highlight that the cell efficiency of \sim 28 % could be achieved under AM1.5 illumination with an optimal cell design. These modeling insights provide useful guidelines for the future development of exploratory window layers for silicon solar cells using NiO (front) and TiO2 (back) heterojunctions. [ABSTRACT FROM AUTHOR]

Different polyelectrolyte multilayers of Polyethilenimine (PEI) and Polyacrylic Acid (PAA) have been assembled onto β-Ni(OH) 2 nanoplatelets using a simple one-pot route by means of consecutive adsorption (Layer by layer method, LbL). The increase of the number of the layers, from 1 to 5, has been varied to tune the microstructure of supercapacitor electrodes and try to improve their physical properties (specific surface, porosity, etc.) which would increase the specific capacitance in the final device. For this, three stabilized suspensions, prepared with modified nanoplatelets with 1, 3 and 5 layers, were shaped by Electrophoretic Deposition (EPD) onto Ni foils and Ni foam. The effect of the LbL on the final microstructure of the ceramic semiconductor material was evaluated in terms of pseudocapacitance. [ABSTRACT FROM AUTHOR]

Highly mesoporous structure nickel cobalt oxides with an ultra-high specific surface area are synthesized through a sol-gel method by using silica derived from tetraethoxysilane hydrolysis as a template. The structural and morphological characteristics of the oxides are determined using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and N adsorption experiments. The electrochemical properties, including capacitance, of the oxides are analyzed through cyclic voltammetry, AC impedance spectroscopy, and charge-discharge tests in 7 M KOH under ambient conditions. The as-prepared nickel cobalt oxides possessing an ultra-high specific surface area of 438.3 m g and a mesoporous structure exhibit a high specific capacitance of 1157.7 F g and a long-term cyclic stability (97.13 % capacity retention after 5000 cycles). Thus, the prepared oxides are promising for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Undoped and nitrogen (N) doped nickel oxide (NiO) thin films were deposited onto glass substrates using a simplified spray pyrolysis technique with two different doping levels of N (10 and 20 at-%). The effects of N doping level on the structural, electrical and optical properties were studied and reported. From the structural studies, it is found that the preferential orientation changed from (111) to (200) for higher concentrations. The optical studies revealed that the average optical transmittance and optical band gap decreased (from 3·5 to 3·4 eV) due to N doping. The electrical resistivity decreased by one order (from 3·84E+03 Ωcm to 5·38E+02 Ωcm) in the case of higher doping of N. The defects generated by N doping were analysed using the photoluminescence studies. The size of the grains decreased due to N doping as seen from SEM studies. [ABSTRACT FROM AUTHOR]

The nickel oxide nanoparticles were synthesized and their effects were evaluated on the visual system of the vertebrate eye. The physico-chemical characterization of the prepared nanoparticles was carried out through transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements. Electroretinography (ERG) was used to evaluate the possible effects of the nickel oxide nanoparticles on the visual system. TEM and XRD measurements demonstrated that the size of nickel oxide nanoparticles was in the range of 4-10 nm. ERG results showed that nickel oxide nanoparticles markedly improve ERG b-wave amplitude during dark-adapted and in the presence of background light. Nickel oxide nanoparticles increased visual sensitivity by 0.4 log units of light intensity and also shortened the time required for rhodopsin regeneration. In conclusion, nickel oxide nanoparticles have positive effects on visual processes in vertebrate eye. [ABSTRACT FROM AUTHOR]

CdSeS quantum dots (QDs) are fi rstly introduced into a NiO photocathode for photocathodic dye-sensitized solar cells (p-DSCs). The optimized sample exhibits a short-circuit density (14.68 mA cm−2) and power conversion effi ciency (1.02%) that are almost one order of magnitude higher than the reported value of p-QDSCs. Steady-state photoluminescence and time-resolved photoluminescence measurements indicate that the photoexcited holes can be almost completely injected from CdSeS QDs into the valence band of NiO. At the same time, it can be observed from electrochemical impedance spectra measurements. [ABSTRACT FROM AUTHOR]

The NiO electrode material has been successfully synthesized by a facile and simple hydrothermal method with the subsequent calcination. Compared with the original work, we omitted the calcination procedure before the hydrothermal reaction. The prepared samples were characterized by scanning electron microscope, X-ray diffraction. The electrochemical performances were investigated by cyclic voltammetry, galvanostatic charge-discharge and cycle life. The result shows the similar morphology with the NiO that underwent the calcination procedure and an enhanced capacitance of 250 F/g at 0.5 A/g was achieved. Furthermore, the material showed excellent cycle-life stability after 2,000 cycles, indicating the great application potential in supercapacitors. [ABSTRACT FROM AUTHOR]

Undyed mesoporous NiO in the configuration of thin film (thickness 2-3 μm) presents photoelectrochemical activity as cathode of a p-type dye-sensitized solar cell (p-DSC) towards the reduction of triiodide to iodide under irradiation with a solar simulator. The photoelectroactivity of the oxide prepared via microwave plasma sintering (or rapid discharge sintering, RDS) has been observed in the spectral range 300-500 nm with the incident photon-to-current conversion efficiency (IPCE) reaching a maximum of 8.7 % at 375 nm. Upon sensitization, the characteristic photoelectrochemical activity of NiO can be either enhanced or depressed depending on the nature of the dye-sensitizer. The comparative analysis of the JV and IPCE curves of the p-DSCs based on bare NiO and four differently sensitized NiO cathodes reveals that N719, black dye (BD), and commercial squaraine 2 (SQ2) decrease the efficiency of conversion of dyed NiO with respect to bare NiO in the range of photoelectroactivity of the latter (300-500 nm). The fourth dye P1 represents the sole exception since its employment brings about an enhancement of the quantum efficiency of P1-sensitized vs. unsensitized NiO up to a maximum of 21 % within the spectral interval of reference for NiO (300-500 nm). Outside the range of NiO photoelectrochemical activity, i.e., λ > 500 nm, only N719 does not introduce a gain of quantum efficiency with respect to bare NiO despite the observation of spectral sensitization up to 580 nm for N719-sensitized NiO. The impedance spectra recorded under illumination shows a direct proportionality between the overall efficiency ( η) of the variously sensitized p-DSCs and the amplitude of the semicircle which is generally associated with the process of charge recombination at the electrode/electrolyte interface with η decreasing with the increase of the recombination resistance. [ABSTRACT FROM AUTHOR]

Synthesis and structural properties of nickel oxide-gadolinium doped ceria (GDC) nanocomposite via sol-gel/electrospinning route were investigated for the first time, and the results were compared with those obtained through gel combustion method. Various analytical techniques, such as XRD, SEM, EDS, TEM and BET, were used to characterise the prepared samples. The electrospinning process resulted in the nanocomposite powder with specific surface area of 145·8 m2 g−1, whereas in the case of the gel combustion method, it was about 9·6 m2 g−1. The bulk densities of the nanocomposites prepared via electrospinning and gel combustion methods were found to be 4·08 and 4·8 g cm−3 respectively. Finally, an attempt was made to evaluate the electrochemical properties of the electrolyte supported Ni-GDC/yttria stabilised zirconia (YSZ)/lanthanum strontium manganate (LSM) cell, using the fibre derived material as the anode and hydrogen as the fuel. The results indicated that the maximum power density and the open circuit voltage of the cell were 55 mW cm−2 and 1·2 V at 800°C respectively. [ABSTRACT FROM AUTHOR]

Nanostructured nickel oxide (NiO) photoelectrodes were fabricated with controlled morphology and texture using single-step aerosol-assisted chemical vapour deposition (AACVD). The durable one-step film fabrication process resulted in highly crystalline columnar structure. Texture controlled films were also fabricated from granular to crystalline columnar morphology by controlling the deposition temperature. The thin film electrodes are highly reproducible and possess an optical bandgap of ∼3.7 eV and exhibit cathodic photocurrent. (© 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

6-Phosphate aminopurine (PA), a purine analog, is usually used in clinical anticancer treatment and biochemical research. Up to now, to the best of our knowledge, no literature about the electrochemical behaviors of PA has been reported. In this study, nano-p-n junction heterostructures based on TiO nanobelts were produced by the assembly of p-type semiconducting NiO nanoparticles onto the n-type surface-coarsened TiO nanobelts. The electrochemical behaviors of PA were investigated by different voltammetric techniques in a phosphate buffer solution of pH 7.4 using the heterostructures as the sensing electrode. Compared with single-phase TiO nanobelt electrodes, the resulting chemically modified electrodes exhibited higher surface accumulation ability and enhanced electrocatalytic activities in the oxidation for PA, with an irreversible oxidation peak at +0.91 V. It is proposed that the nano-p-n junction heterostructures played an important role in the enhancement of charge transport in the sensing electrodes. The results suggest that the nanoengineered TiO nanobelts might be a promising candidate for biosensing applications of nucleic acid drugs that will be of significance to diagnostic medicine and molecular biology research. [ABSTRACT FROM AUTHOR]

Herein, we report the in situ growth of single-crystalline Ni(OH)2 nanoflakes on a Ni support by using facile hydrothermal processes. The as-prepared Ni/Ni(OH)2 sponges were well-characterized by using X-ray diffraction (XRD), SEM, TEM, and Xray photoelectron spectroscopy (XPS) techniques. The results revealed that the nickel-skeleton-supported Ni(OH)2 rope-like aggregates were composed of numerous intercrossed single-crystal Ni(OH)2 flake-like units. The Ni/Ni(OH)2 hybrid sponges served as electrodes and displayed ultrahigh specific capacitance (SC=3247 Fg-1) and excellent rate-capability performance, likely owing to fast electron and ion transport, sufficient Faradic redox reaction, and robust structural integrity of the Ni/Ni(OH)2 hybrid electrode. These results support the promising application of Ni(OH)2 nanoflakes as advanced pseudocapacitor materials. [ABSTRACT FROM AUTHOR]

Nickel oxide thin films were prepared by the sol–gel technique combined with spin coating onto glass substrates. The as-deposited films were pre-heated at 275°C for 15min and then annealed in air at different temperatures. The effects of the annealing temperature on the structural and optical properties of the films are studied. The results show that 600°C is the optimum annealing temperature for preparation of NiO films with p-type conductivity and high optical transparency. Then, by using these optimized deposition parameters, NiO thin films of various thicknesses were deposited at the same experimental conditions and annealed under different atmospheres. Surface morphology of the films was investigated by atomic force microscopy. The surface morphology of the films varies with the annealing atmosphere. Optical transmission was studied by UV–vis spectrophotometer. The transmittance of films decreased as the thickness of films increased. The electrical resistivity, obtained by four-point probe measurements, was improved when NiO layers were annealed in N2 atmosphere at 600°C. [ABSTRACT FROM AUTHOR]