Surface Of Nickel Foil Research Articles

The Laser Influence on the Formation of Ni-Al Compounds in the Nickel Foil Surface Layers Depending on the Laser Radiation Power Density

The Laser Influence on the Formation of Ni-Al Compounds in the Nickel Foil Surface Layers Depending on the Laser Radiation Power Density

The Electrophoretic Deposition of Lithium Cobaltate Nanosized Particles on the Surface of Metals and Electroconductive Oxide Ceramics

The deposition of LiCoO2 nanosized particles synthesized in LiCl–CoCl2 melts on the surface of nickel foil, copper, chrome–cobalt alloy, and platinum mesh in aqueous solutions of lithium chloride at the room temperature as well as on the surface of the electron-conducting La0.6Sr0.4MnO3 oxide ceramics in chloride melt at temperature of ca. 700°C is studied. The methods of vibrational spectroscopy, X-ray photoelectron spectroscopy, ellipsometry, and scanning electron microscopy have revealed the features of the chemical composition, structure, and morphology of the precipitates obtained.

Heterostructured Palladium–Nickel Sulfide on Plasma-Activated Nickel Foil for Robust Hydrogen Evolution

Transition-metal sulfides are among the effective electrocatalyst candidates for H2 evolution (HER); however, they still cannot compete with Pt-based electrodes for renewable energy applications. To overcome this issue, grid-matched palladium–nickel sulfides (Pd4S/Ni3S2) are successfully engineered on the holey surface of nickel foil (HNF), which is first treated with a non-thermal plasma (HPNF) generated by a dielectric barrier discharge. The synthesized heterogeneous Pd4S-Ni3S2/HPNF catalyst results in the electron redistribution on the phase interfaces, enhancing the desorption ability of H* species. Consequently, Pd4S-Ni3S2/HPNF presents a high HER activity, and the overpotentials for generating 10 (j10) and 500 (j500) mA/cm2 are about 44 and 247 mV. Meanwhile, the catalyst retains good electrocatalytic stability over 50 h at j100. In addition, the H2 amount of Pd4S-Ni3S2/HPNF driven by the current j10 can reach 11.25 mmol/h, which is competitive with other presently available high-performance electrocatalysts. The theory and in situ Raman spectroscopy results indicate that Pd4S and the heterointerfaces between the Pd4S and Ni3S2 phases are the main active catalytic sites for H2 evolution and that the Pd weakens the S–Hads bonds, enhancing the reactive kinetics of the Volmer and Heyrovsky steps. This work provides a new and green approach for engineering highly active and stable electrocatalysts for clean hydrogen production.

Electrochemical Preparation of Highly Oriented Microporous Structure Nickel Oxide Films as Promising Electrodes in Urea Oxidation

Abstract Highly oriented microporous nickel oxide films were prepared through the simple and fast anodization of nickel foils at 30 V, followed by calcination at 400 °C. Low concentrations of ammonium chloride and potassium hydroxide solutions, which were dispersed in ethylene glycol, were used as electrolytes. Microporous dimensions and large surface areas of the films were obtained by using both electrolytes. The ammonium chloride system provided a highly oriented microporous structure with excellent distribution of pores at the surface of nickel foil. On the contrary, it was not uniform in the potassium hydroxide system. Furthermore, cyclic voltammetry of the microporous films in alkaline solutions containing urea showed the highest oxidation currents at the nickel oxide films prepared in the ammonium chloride system. This nickel oxide film also showed excellent stability of the current responses, indicating that the method has potential to be applied in electrode preparation, especially urea oxidation.

Effect of the Oxidation Degree of a Nickel Foil Surface on Its Catalytic Activity in the Reaction of Ethylene Oxidation

The effect of the oxidation degree of a nickel foil surface on the rate of catalytic oxidation of ethylene was studied by a pulse method at 600 and 700°C. It was shown that a reduced metallic surface demonstrated a high activity in partial ethylene oxidation, whereas a partially oxidized surface with an oxidation degree of ~24 formal O2 monolayers, in the total oxidation of C2H4. A SEM investigation has revealed that the oxidized surface was partially coated with nickel oxide nanocrystals. A further increase in the surface oxidation degree led to a continuous coverage of the Ni surface with oxide crystals and a dramatic decrease of catalytic activity. In addition, a low maximum of total ethylene oxidation was observed at 700°C in the range of surface oxidation degree of 95–135 O2 monolayers.

Quasi homoepitaxial growth of modified diamond: Nickel-substrate catalytic multilayer graphene transforming to diamond

Defects can be generated when growing diamond on heterogeneous substrates. The problem dampers the widespread use of diamond films. In this paper, a novel approach is proposed which grows diamond on graphene quasi-homogeneous epitaxial substrate. Results showed that high quality diamond was synthesized on a quasi homoepitaxial graphene substrate through sp2-sp3 hybridization and covalent bond transformation. Firstly, D peak-free graphene was synthesized on nickel metal surface. C–H and CC bonds were then exploited to produce dehydrogenation and coupling reaction which caused the transform of graphene to transform into diamond. In virtue of the superior intermiscibility and catalysis of nickel to carbon, few-layer graphene grew efficiently on nickel foil surface. An internal space microstructure network of carbon atoms was produced through different non-covalent interactions. At last, graphene is converted into diamond. This process can also be used to synthesize hydrophilic porous diamond film. It is a promising approach to the development of new graphene/diamond-based components in the future.

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.

Experimental study of heat transfer characteristics of high-velocity small slot jet impingement boiling on nanoscale modification surfaces

Jet impingement boiling is one of the most efficient methods to increase the critical heat flux. Through controlling surface chemical properties and topography, plain nickel foil surface, three kinds of plain nickel-based chemical treatment surfaces and four kinds of nickel-based electrochemical treatment surfaces with nanocone array structure were used in the jet impingement boiling experiments to investigate the quantitative effects and the effect mechanism of the surface characteristic parameters, including nanoscale roughness (Ra): solid–liquid contact angle (CA) and effective heat transfer area ratio (r: the ratio of the actual heat transfer area to its projected area) on the heat transfer coefficient (HTC) and the critical heat flux (CHF). It is revealed that: similar to the heat transfer in pool boiling, changing nanoscale Ra has little effect on the heat transfer characteristics; decreasing solid–liquid CA can enhance the HTC while worsen the CHF obviously; increasing r can intensify both the HTC and the CHF. Predictive correlations of the HTC and the CHF of jet impingement boiling which include the effects of surface characteristics are presented. The predictive correlations presented can be widely used in various conditions with different working fluids and heating surfaces.

Origin of temperature oscillations of nickel catalyst occurring in methane oxidation

The catalytic oxidation of methane over a nickel foil has been investigated in a wide range of methane: oxygen molar ratios at a constant reactor temperature of 680°C. Under oxygen-deficient conditions, the reaction takes place in the self-oscillating mode. Stable self-sustained oscillations of the methane oxidation rate are observed in the CH4: O2 molar ratio range from 2: 1 to 19: 1. This process is accompanied by catalyst temperature oscillations, whose amplitude reaches 80°C. It has been demonstrated by scanning electron microscopy that the origination of the self-sustained oscillations is accompanied by morphological changes in the catalyst surface. Under the action of the reaction medium, a porous layer 5–10 µm in thickness forms on the nickel foil surface. The mechanism of methane oxidation over nickel that accounts for the onset of the self-sustained oscillations is discussed. This mechanism is based on periodical nickel oxidation and reduction. When nickel is in the high-activity state, it is mainly in metallic form, and the passage of nickel into its low-activity state is accompanied by the formation of a nickel oxide layer on the foil surface. The reduction of this nickel oxide causes a periodic decrease in the catalyst temperature. The total and partial oxidations of methane on the reduced surface of the nickel foil raise the catalyst temperature. Under oxygen-deficient conditions, a carbon deposit builds up on the catalyst surface, and the combustion of this deposit complicates the catalyst temperature oscillation profile.

Experimental study on the saturated pool boiling heat transfer on nano-scale modification surface

Plain nickel foil surface, three kinds of plain nickel-based chemical treatment surfaces and four kinds of nickel-based electrochemical treatment surfaces with nano-cone array structure were used in the pool boiling experiment. The quantitative effects and the effect mechanism of the surface characteristic parameters, including nano-scale roughness (Ra), solid–liquid contact angle (CA) and effective heat transfer area ratio (r: the ratio of the actual heat transfer area and its projected area) on the heat transfer coefficient (HTC) on the modification plain surfaces and nano-cone array surfaces were studied and summarized. By improving the previous proposed the HTC prediction correlation for the common plain surfaces (without considering the effect of r), a new uniform correlation is proposed and it can well predict the HTC of the heated surface with simple convex structure (with considering the effect of r). In addition, the bubble dynamic characteristics including the bubble departure diameter, the bubble departure frequency, the active bubble nucleation site density and the combined bubble were investigated by visualization research. These results proposed some mechanism support for the new predicting correlation.

Rate constant for heterogeneous dissociation of fluorine in a temperature range of 700–900 K on a nickel surface

The aim of the present work was the study of dissociation kinetics of molecular fluorine on the hot surface of a nickel catalyst. The concentration of fluorine atoms was measured by EPR spectroscopy using molecular oxygen as a reference. The fluorine atom concentration was measured with an random error of about 3%. Molecular fluorine dissociation on the walls of a heated nickel tubes was measured. For process simulation and analysis of the experimental curves a one-dimensional kinetic model of the reactor which did not take into account axial and radial diffusion of the gas in the reactor and radial gas speed distribution was used, but account was taken of the pressure drop in the reactor and tubes between the reactor and ESR spectrometer. In the experiments we measured the fluorine atom concentration dependencies on the gas flow velocity and fluorine pressure (10–30 Torr). The dissociation constant on the surface of nickel foil is k d =(2.4±0.7)×10 4 exp [−(19 000±500)/RT] cm/s (at 700–900 K), the probability of heterogeneous recombination on the nickel surface γ = (2.2 ± 0.5) × 10 −4, rate constant of the three-body gas phase recombination on molecular fluorine as `third' body at room temperature k rec = (4.7 ± 1.2) × 10 −34 cm 6/s. This last value coincides with literature value. Our measurements confirmed the value of the equilibrium constant of the fluorine dissociation process: K = 1.11 × 10 25 exp(−37 840/ RT)cm −3 ( K is expressed in cal/mole).

Surface mediated radical recombination luminescence: O+NO+Ni

Results of an experimental investigation of the chemiluminescence produced by the interaction of atomic oxygen and nitric oxide on a nickel foil surface are reported. Visible luminescence which depends linearly on the atomic oxygen and nitric oxide fluxes, on the substrate temperature, and on the substrate temperature history has been observed under conditions for which the three-body gas-phase reaction of O and NO is negligible. The intensity of the luminescence is greater than can be accounted for by the gas-phase two-body radiative recombination reaction of O and NO. The time, flux, and temperature dependences, along with the intensity of the emission support strongly the notion that the observed luminescence stems from excited species, most probably electronically excited NO2, formed in a surface mediated reaction.

The reaction of carbon and water as catalyzed by a nickel surface

Many of the individual steps which make up the reaction of carbon and water to produce CO and H 2 were studied on a nickel foil surface using temperature-programmed reaction spectroscopy (TPRS), Auger electron spectroscopy (AES), and ultraviolet photoelectron spectroscopy (UPS). Surface graphite and carbide, two metastable surface carbon forms, were prepared by dehydrogeneration of C 2 H 2 and served as reactant carbon. UPS of the graphite monolayer in contact with the metal yielded a valence electronic structure that could be interpreted in terms of the bulk band structure of graphite. The fully carbided Ni surface was active for H 2 O dissociation with an estimated activation energy ≤ 5 kcal/mol. The reaction of graphitic carbon in contact with the nickel surface and adsorbed oxygen occurs directly without isolated prior breaking of carbon-carbon bonds. The estimated activation energy for the direct reaction was 44 kcal/mol. A different catalytic reaction cycle involving carbon-carbon bond breaking followed by oxidation of the carbide is energetically more demanding. The activation energy for direct carbon-carbon bond breaking was estimated to be between 65 and 70 kcal/mol. Following this demanding step, the reaction between carbidic carbon and oxygen proceeded with estimated activation energy of 31 kcal/mol.

Characterization of carbons formed on nickel surfaces

Carbonaceous materials formed in small quantities (⩽4 mg) on nickel surfaces by pyrolysis of buta-1,3-diene and propene have been characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in conjunction with electron and X-ray diffraction techniques, laser Raman studies, density measurements, hydrogen microanalysis and plasma gasification experiments. The products identified were nickel carbide, a disordered carbon of columnar morphology, a more-ordered laminar material, filamentous carbon and a polymeric species that condensed out as droplets on the nickel foil surface during cooling. The relative amounts of these products were dependent upon the temperature of reaction as measured at the centre of the foil. The different forms of carbonaceous material could be produced simultaneously on the foil surface as a consequence of the temperature gradient along the length of the foil. The formation of carbon on thin crystalline evaporated films of nickel is also described and compared with deposition on the bulk nickel foils. Carbon growth mechanisms are discussed.