Nickel Foil Research Articles

Chirality and grain boundary effects on indentation mechanical properties of graphene coated on nickel foil

We investigate chirality and grain boundary (GB) effects on indentation mechanical properties of graphene coated on nickel foil using molecular dynamics simulations. The models of graphene with different chirality angles, different numbers of layers and tilt GBs were established. It was found that the chirality angle of few-layer graphene had a significant effect on the load bearing capacity of graphene/nickel systems, and this turns out to be more significant when the number of layers is greater than one. The enhancement to the contact stiffness, elastic capacity and the load bearing capacity of graphene with tilt GBs was lower than that of pristine graphene.

Enhanced Self-Biased Magnetoelectric Coupling in Laser-Annealed Pb(Zr,Ti)O3 Thick Film Deposited on Ni Foil.

Enhanced and self-biased magnetoelectric (ME) coupling is demonstrated in a laminate heterostructure comprising 4 μm-thick Pb(Zr,Ti)O3 (PZT) film deposited on 50 μm-thick flexible nickel (Ni) foil. A unique fabrication approach, combining room temperature deposition of PZT film by granule spray in vacuum (GSV) process and localized thermal treatment of the film by laser radiation, is utilized. This approach addresses the challenges in integrating ceramic films on metal substrates, which is often limited by the interfacial chemical reactions occurring at high processing temperatures. Laser-induced crystallinity improvement in the PZT thick film led to enhanced dielectric, ferroelectric, and magnetoelectric properties of the PZT/Ni composite. A high self-biased ME response on the order of 3.15 V/cm·Oe was obtained from the laser-annealed PZT/Ni film heterostructure. This value corresponds to a ∼2000% increment from the ME response (0.16 V/cm·Oe) measured from the as-deposited PZT/Ni sample. This result is also one of the highest reported values among similar ME composite systems. The tunability of self-biased ME coupling in PZT/Ni composite has been found to be related to the demagnetization field in Ni, strain mismatch between PZT and Ni, and flexural moment of the laminate structure. The phase-field model provides quantitative insight into these factors and illustrates their contributions toward the observed self-biased ME response. The results present a viable pathway toward designing and integrating ME components for a new generation of miniaturized tunable electronic devices.

Graphene produced by carbon diffusion through nickel foil

This paper presents results of obtaining graphene and few-layer graphene nanostructures byunconventional method consisting in the diffusion of carbon through a thin nickel foil. The production ofgraphene and few-layer graphene nanostructures by the diffusion method was carried out under highvacuum conditions, with resistive heating of nickel. The growing method presented by us makes itpossible to control the process of graphene formation by changing parameters such as: temperature, timeand thickness of nickel. Data on the time dependence of the diffusion process on the nickel thickness andtemperature are given. From the obtained experimental data was found the parameters determining thediffusion dynamics: Eɑ - the activation energy and concentration diffusion coefficient. The obtainedsamples were investigated by optical and electron microscopy, as well as by Raman spectroscopy. Theexperimental results are in good agreement with the theoretical Arrhenius relation, which confirms thediffusion nature of the process.

Deposition of nickel oxide nanoworms on anodized nickel foil substrates as highly effective thin-film microextraction sorbents to determine caffeine

A very thin film of NiO nanoworms was successfully grown on an anodized Ni foil and used for TFME of caffeine in beverages and urine samples. The method was simple, fast and affordable.

Hierarchically Structured Ni Nanotube Array-Based Integrated Electrodes for Water Splitting

The development of high-performance nonprecious electrocatalysts for overall water splitting has attracted increasing attention but remains a vital challenge. Herein, we report a ZnO-based template method to fabricate Ni nanotube arrays (NTAs) anchored on nickel foil for applications in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). On the basis of this precursor electrode, the three-dimensional NiSe2 NTAs of unique sandwich-like coaxial structure have been fabricated by electrodeposition of NiSe2 on Ni NTAs, which exhibits high performance toward the HER in both acidic and alkaline media. The method based on Ni NTAs can be readily extended to fabricate Ni2P NTAs by gas–solid phosphorization for the HER, and NiFeOx NTAs by anodic codeposition of Ni and Fe for the OER. Consequently, an alkaline electrolyzer has been constructed using NiFeOx NTAs and NiSe2 NTAs as anode and cathode, respectively, which can realize overall water splitting with a current density of 100 mA cm–2 at an overpotential of 510 mV.

Heat transfer and CHF in subcooled flow boiling of aqueous surfactant solutions

Flow boiling heat transfer characteristics of surfactant solution was studied and compared to that of pure water. The tested fluid was an aqueous solution of cetyltrimethyl ammonium chloride (CTAC) with addition of sodium salicylate (NaSal) at the same mass concentration. Tests were performed with 6.0 × 3.5 mm cross-section channel over flow rate range of 192–403 ml/min, at inlet temperature of 80 °C and an outlet pressure of 101.3 kPa. Liquid column method and resistance method of temperature determination were adopted to obtain accurate experimental data. The present experimental results show that, the flow boiling in CTAC/NaSal solutions at an appropriate concentration (100 ppm, ppm refers to part per million) behaved a good flow boiling performance. The heat transfer coefficient of 100 ppm CTAC/NaSal solution at the critical heat flux (CHF) was increased to 1.36 times compared to that of pure water. Besides, the CHF of 0.08 mm thick Nickel foil was increased to about 126% by surfactant addition when the concentration was beyond 100 ppm. The addition of CATC/NaSal increased the nucleation site density and inhibits bubble coalescence which were likely to be causes of enhancing the boiling heat transfer coefficient and CHF of subcooled flow boiling of CATC/NaSal aqueous solutions.

Metastable Fluid Decay During Electric Explosion of Metallic Foils

Results of experimental investigations into overheated metastable fluid decay during electric explosion of metallic foils are presented. Experiments have been performed using an experimental complex consisting of three current generators, one of which provides explosion of foil and two others – X-pinch-based radiographs – are used for diagnostic purposes. The upper limit of the decay time of an overheated metastable metal is determined experimentally. For aluminum conductor with deposited energy of (5.3 ± 0.5) kJ/g, the metastable state decay time is ~110 ns; for copper foil with deposited energy of (2.4 ± 0.2) kJ/g, it is ~260 ns; and for nickel foil with deposited energy of (1.3 ± 0.3) kJ/g, it is ~350 ns.

In Situ Control of CVD Synthesis of Graphene Film on Nickel Foil

Here we present a detailed study of the chemical vapor deposition (CVD) method used in a real‐time regime for graphene film fabrication on nickel foils. Thin films with a wide range of thicknesses (from 3 up to 53 layers and more) have been obtained. A home‐made cold‐wall chamber for CVD realization is demonstrated in this work. It is supplied with tools for in situ monitoring the temperature‐dependent electrical resistance of nickel substrate to obtain a desired number of graphene layers in the sample synthesized. An area of 1 × 1 cm2 appeared to be covered by graphene. Raman spectroscopy and optical absorption spectroscopy are used to estimate the quality of graphene films fabricated and the graphene layer number.

Magnetoresistance effect in ferromagnetic metal foil

The paper presents the results of investigating how electric current and a permanent external magnetic field affect the magnitude of magnetoresistance effect (MRE) in polycrystalline nickel foils. For a current density of j = 2.5·108 A/m2 the maximum MRE we obtained for our foil samples (25x2x0.005 mm strips) was 11.6%. We studied the effect of external magnetic fields, when Ho = (0.5…6) ·105A/m, on the MRE magnitude in polycrystalline nickel foils through which we simultaneously passed electric current with densities in the j = (1...4)·108 A/m2 range. We found that the maximum MRE value (10.7 %) results from increasing the external magnetic field Ho up to 6·105 A/m when the current in the sample is fixed at j = 3·108 A/m2. These results may stem from the fact that the electric current may cause electroplastic softening of the foil material, which leads to additional magnetization. The current value is the threshold for starting the dislocation motion and restructuring the conductive material. Varying the external magnetic field controls the decrease in magnetization dispersion in nickel foils.

The use of electrochemical deposition of metals at the surface microstructuring by laser ablation in liquids

Micron, submicron, surface-periodic and nanostructures were obtained by laser ablation in a liquid method on the titanium plate surface and the nickel foil surface. Electrochemical deposition of the nickel in the modified region of the titanium leads to the formation of conical structures 6 μm in height and filamentary nanostructures on the separated film. During deposition on the laser-modified nickel target, the separable film retains the period of the structures from which it is removed. The component titanium target coated with a nickel film was also irradiated. After separation of the nickel film, perforations with an average diameter of 1 μm and holes up to 50 μm in diameter were detected.

Fabrication of NiSe2 by direct selenylation of a nickel surface

Abstract The emergence of transition metal dichalcogenides (TMD) as an exciting class of materials with appealing potentials in electronic and optoelectronics has drawn intensive attention in the past few years. Herein, we report the fabrication of NiSe2, which has been predicted to be a promising candidate in the field of electrocatalyst, by direct selenylation of the nickel substrate after epitaxial growth of selenium on a nickel foil. With a combination of photoelectron spectroscopy (PES), X-ray diffraction (XRD), scanning electron microscopy (SEM) and density function theory (DFT) calculations, it is possible to identify the phase transition among the previously reported stable Ni-Se phases and the ultimate formation of NiSe2 species by external annealing at varying temperatures. While SEM reveals the morphology of NiSe2 film with flat terraces, XRD, XPS and DFT calculations demonstrate that NiSe2 is the relatively stable phase formed on the Ni substrate from the cohesive energy point of view. Furthermore, valence band spectra point out the nonmetallic level of these different Ni-Se compounds, agreeing well with literature reports. In the end, our report may indicate a feasible approach to synthesize the pure NiSe2 species under solution-free condition and an encouraging step forward towards non-noble electrocatalysts.

Synthesis and Characterization of NiO Nanostructures Formed By Anodization Sonoelectrochemical. Its Application As Non-Enzymatic Glucose Sensor

The electrochemical determination of glucose concentration through the use of a non-enzymatic system is a priority purposes in recent decades. For this reason, many researchers have focused their studies on the development of sensors of this nature. For this purpose, they have proposed the use of new materials such as metals and metal oxides. In this context, we conducted a study of the synthesis and characterization of the electrical and morphological properties of nickel oxide (II) type - p (p-NiO), all this in order to evaluate it as a possible nonenzymatic sensor glucose molecule. Despite the above, the nickel oxide has a low diffusion rate of charge carriers. Therefore, new synthesis routes leading to a nanostructured oxide is required, so that the photogenerated electrons are accumulated in the vicinity of the surface. This is to facilitate the transfer process of charge per on the recombination. This report shows the results concerning the preparation sonoelectrochemical of NiO nanostructures (NN). Nanostructured NiO layers have been electrochemically grown by ultrasound-assisted anodization of nickel foils (Advent, 99.0%, 0.1 mm) at a potential of 50 V in ethylene glycol (EG; 99.8%, anhydrous), ammonium fluoride (0.5 wt% NH4F) and wt 5.0% DI water. The anodization experiments were carried out using ultrasonic waves (37 kHz, 60 W) and were carried out for 300 s at different temperatures. The above process was carried out using a two-electrode system (flag shaped 1.0 cm2 Ni foil as anode and carbon plate, 22.55 cm2 as cathode; the distance between cathode and anode was kept at 3 cm). Two different nickel substrates have been assayed, i.e.: (i) bare nickel foils, and pre-treated nickel substrates by anodic polarization for 2 hours in a 0.1 M KX (X = F- o Cl-) in aqueous solution at -0.18 V. The resulting NiO nanostructures (NN) will then be named as: NN(w/o) and NN (−0.18 V), respectively. The electrochemical pretreatment process of nickel substrates was carried out using a conventional electrochemical cell with a three-electrode arrangement. As a reference electrode, an Hg/Hg2SO4 (SME, 0.650 V vs. NHE) has been used, and a platinum spiral and a nickel sheet of 1.0 cm2 constituted the counter and working electrode, respectively. The anodized samples are properly washed with distilled water, to remove the occluded ions, and dried in a furnace. Moreover, nanostructured NiO layers obtained were analyzed morphologically by atomic force microscopy (AFM), Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS). The results obtained for nickel oxide as a non-enzymatic glucose sensor are preliminary and are being analyzed by authors.

In Situ Observation of Thermal Proton Transport through Graphene Layers.

Protons can penetrate through single-layer graphene, but thicker graphene layers (more than 2 layers), which possess more compact electron density, are thought to be unfavorable for penetration by protons at room temperature and elevated temperatures. In this work, we developed an in situ subsecond time-resolved grazing-incidence X-ray diffraction technique, which fully realizes the real-time observation of the thermal proton interaction with the graphene layers at high temperature. By following the evolution of interlayer structure during the protonation process, we demonstrated that thermal protons can transport through multilayer graphene (more than 8 layers) on nickel foil at 900 °C. In comparison, under the same conditions, the multilayer graphenes are impermeable to argon, nitrogen, helium, and their derived ions. Complementary in situ transport measurements simultaneously verify the penetration phenomenon at high temperature. Moreover, the direct transport of protons through graphene is regarded as the dominant contribution to the penetration phenomenon. The thermal activation, weak interlayer interaction between layers, and the affinity of the nickel catalyst may all contribute to the proton transport. We believe that this method could become one of the established approaches for the characterization of the ions intercalated with 2D materials in situ and in real-time.

Characterization of prompt neutron spectrum of the Missouri University of Science and Technology Reactor

An activation-foil method was used to obtain the energy spectrum of the prompt-neutron flux at the Missouri University of Science and Technology Reactor (MSTR). The foils were irradiated at the center of the reactor core (120W configuration). The neutron spectrum was determined using the unfolding method implemented in the SAND-II code. Multiple foils of dysprosium, vanadium, indium, gold, aluminum, copper, cobalt, silver, nickel, and iron were placed at the source holder position and irradiated for 3min each at 100kW. The foil set cover energies from 0.025eV to 7.2MeV for a broad spectrum analysis. After irradiation, the sample was cooled using water until the dose rate reached a level that allowed safe handling. For each material, both bare and cadmium covers were used to obtain the thermal and epithermal neutron flux. The activity of each foil was determined by counting for 3min with a high-purity germanium detector, and the results were used in SAND-II to obtain the neutron flux spectrum for the MSTR. Monte Carlo N-particle (MCNP) model was used to obtain the initial guess of the spectrum at the source holder position, which was used as input for SAND-II. The spectrum is unfolded using two different energy binning structures in the initial guess for SAND-II. As expected, the results provided highly thermal neutron spectra in source-holder environment, where water thermalizes most of the neutrons; 93% of the total flux at the source-holder position is no greater than 0.55eV for the 120W reactor-core configuration. The epithermal and fast neutrons were 6% and 1%, respectively at fast/epithermal energy boundary of 100keV. A similar experiment and analysis in the past determined that 7%, 38% and 55% of the total flux at the source-holder position were respectively thermal, epithermal and fast for the 101W configuration. Notwithstanding the difference between the two configurations, the current determination is an improvement to the characterization of the MSTR flux. This is because 7% thermal flux is unlikely in an environment primarily surrounded by water. The total neutron flux calculated by MCNP is 4.98×1011±1.72×1010n/cm2s. The flux determined through SAND-II is 4.79×1011±6.10×1010n/cm2s; a difference of 4%.

Laser-assisted chemical vapor deposition setup for fast synthesis of graphene patterns.

An automatic setup based on the laser-assisted chemical vapor deposition method has been developed for the rapid synthesis of graphene patterns. The key components of this setup include a laser beam control and focusing unit, a laser spot monitoring unit, and a vacuum and flow control unit. A laser beam with precision control of laser power is focused on the surface of a nickel foil substrate by the laser beam control and focusing unit for localized heating. A rapid heating and cooling process at the localized region is induced by the relative movement between the focalized laser spot and the nickel foil substrate, which causes the decomposing of gaseous hydrocarbon and the out-diffusing of excess carbon atoms to form graphene patterns on the laser scanning path. All the fabrication parameters that affect the quality and number of graphene layers, such as laser power, laser spot size, laser scanning speed, pressure of vacuum chamber, and flow rates of gases, can be precisely controlled and monitored during the preparation of graphene patterns. A simulation of temperature distribution was carried out via the finite element method, providing a scientific guidance for the regulation of temperature distribution during experiments. A multi-layer graphene ribbon with few defects was synthesized to verify its performance of the rapid growth of high-quality graphene patterns. Furthermore, this setup has potential applications in other laser-based graphene synthesis and processing.

Constraints and optimization of the laser microwelding process of thin metal foils

Laser microwelding of thin metal foils of various materials is established in several fields of application. Within all these application fields, a sufficient and reliable welding process is required to join thin metal foils successfully. One crucial function of the weld is often a gas-tight sealing. For instance, titanium foils provide hermetic and sterile packaging of medical implants, and vacuum insulation panels and pressure sensors are assembled from stainless steel foils. Even if gas-tightness is not the aim, weld defects lower the functionality of the product. In the case of a roll imprint process in order to structure optical surfaces on films and panels, where nano-structured nickel foils serve as masters, weld imperfections lead to failures in the optical structure. Furthermore, insufficiently welded cathode foils, which are made of aluminum, cause an increasing electric resistivity. Weld defects during laser microwelding are provoked by thermally induced distortion due to small foil thickness. The distortion causes gaps between the joining partners and can lead to a partial process abortion. Hence, metal foils have to be joined in the deep welding mode, which causes less heat conduction losses than conduction welding. In addition to a defect-free weld seam, a broad process window is required for a reliable and robust process. The process window in laser microwelding is determined by the transitions from a full penetration weld to a fusion cut regime and to an incomplete penetration weld. Furthermore, the onset of humping at higher feed rates decreases the cross-sectional area of the join and, as a consequence, the tensile strength, and has to be avoided in order to achieve a high weld quality. For the purpose of considering all mentioned constraints (deep welding regime, process window broadness, and onset of humping) while designing the process with due regard to the applied material, focal diameter, laser power, and feed rate, a deeper understanding of the process is necessary. The present work gives a qualitative and quantitative overview of the occurrence of these constraints in laser microwelding and determines the ideal working range with respect to the combination of process parameters.

(Invited) Robust Internal Temperature Sensing of Large-Format Li-Ion Cells

Large temperature difference arises in big-size Li-ion cells (e.g. 94Ah Samsung cells) due to low thermal conductivity of battery materials, especially under extreme conditions like high C rate operation at low temperatures or abuse conditions [1]. Previous research [2,3] has attempted to embed micro thermocouples in 18650-format cylindrical cells (1.6 Ah) and demonstrated that internal temperature sensing is more useful than surface temperature sensing in early detection of abnormal thermal behaviors for safety enhancement. For practical applications of this technique, internal temperature sensors must be robust and durable to survive battery life cycle and must be low cost. In this study we developed a new resistance temperature device (RTD) based on nickel foil that meets both criteria. Embedded in 10Ah pouch cells, these in-cell temperature sensors still function well after the cells experienced 2,500 cycles. It is believed that low-cost, durable and reliable in-cell temperature sensors have finally arrived to enable substantial improvement in the Li-ion battery’s high-temperature safety and thermal management.

The Birth of Nickel Phosphide Catalysts: Monitoring Phosphorus Insertion into Nickel

AbstractTri‐n‐octylphosphine (TOP) is used widely as a phosphorating agent to yield metal phosphide nanocatalysts, which are receiving intense attention because of their high performance in both electrochemical and hydrotreatment catalytic processes, such as the hydrogen evolution reaction and the hydrodesulfurization reaction. We used in situ ambient‐pressure X‐ray photoelectron spectroscopy to investigate the formation of nickel phosphide on the surface of a nickel foil at temperatures close to those employed to form nickel phosphide nanoparticles in the colloidal route. We showed that the onset of phosphorus insertion into nickel occurs at as low as 150 °C, which is much lower than that reported previously (>210 °C). Moreover, the formation of sp2 carbon was observed on the surface as the consequence of TOP alkyl chain decomposition. These findings provide new insights into the surface chemistry of metal phosphide nanoparticles, which are increasingly employed in several fields of catalysis. Our results demonstrate that even below 150 °C, significant phosphorus and carbon incorporation can occur during metal nanoparticle syntheses if TOP is employed as the stabilizing agent.

Inductively coupled remote plasma-enhanced chemical vapor deposition (rPE-CVD) as a versatile route for the deposition of graphene micro- and nanostructures

Multiple layers of graphene thin films with micro-crystalline orientation and vertical graphene nano-sheets were grown on different substrates (i.e., polycrystalline nickel foil, Ni(111), highly oriented pyrolytic graphite) using a single-step process based on low-pressure remote Plasma-Enhanced Chemical Vapor Deposition (rPE-CVD). In contrast to previous studies, a novel basic approach to this technique including a new remote inductively coupled RF plasma source has been used to (i) minimize the orientational effect of the plasma electrical fields during the catalyst-free growth of graphene nano-sheets, (ii) warrant for a low graphene defect density via low plasma kinetics, (iii) decouple the dissociation process of the gas from the growth process of graphene on the substrate, (iv) tune the feedstock gas chemistry in view of improving the graphene growth, and (v) reduce the growth temperature as compared to conventional chemical vapor deposition (CVD). In order to study the various aspects of the rPE-CVD graphene growth modes and to assess the characteristics of the resulting graphene layers, Raman spectroscopy, XPS, SEM, and STM were used. The results give evidence for the successful performance of this new rPE-CVD plasma deposition source, that can be combined with in situ UHV-based processess for the production of, e. g., hybrid metal ferromagnet/graphene systems.

Characterization of hexagonal boron nitride layers on nickel surfaces by low-energy electron microscopy

The thickness and interfacial geometry of hexagonal boron nitride (hBN) films grown by chemical vapor deposition on polycrystalline nickel foils is studied using low-energy electron microscopy (LEEM). The reflectivity of the electrons, measured over an energy range of 0–20eV, reveals distinct minima and maxima. The measured data is compared with simulations based on a first-principles description of the electronic structure of the material. From this comparison, the number of hBN layers and the separation between the lowest hBN layer and the nickel surface is deduced. The coupling of interlayer states of the hBN to both image-potential and Shockley-type surface states of the nickel is discussed, and the dependence of the reflectivity spectra on the surface orientation of nickel grains is examined.