Free Nickel Research Articles

Rapid fabrication of binder free nickel cobalt oxide electrodes with dendritic nanostructure for electrochemical energy storage applications

A rapid and facile technique to synthesize nickel cobalt oxide electrodes by photothermal treatment of mixed organometallic precursor solution is reported. Using short and intense pulses of light from a xenon flash lamp, spray coated films are converted into porous nickel cobalt oxide electrodes with dendritic nanostructure. The electrode films fabricated in a few seconds show excellent energy storage properties as supercapacitor electrodes. Specific capacitance of up to 116 Fg−1 and capacitance retention of up to 75 % were observed in samples with low mass loading. Analysis of the cyclic voltammetry (CV) curves shows that capacitance is the dominating charge storage mechanism in these films. To study the effect of varying the mass loading in electrodes, double and triple layered electrodes were also studied. In films with high mass loading, the specific capacitance of the films decreased but areal capacitance continued to increase. A high areal capacitance of up to 243 mFcm−2 is observed in films with high mass loading. CV curve analysis of high mass loading electrodes further shows that in films with higher mass loading, the charge storage mechanism is a mix of capacitance and diffusion processes. The contribution of diffusion increased with increase in the mass loading of the electrodes. This study sheds light into the mechanism of charge storage in electrodes prepared by large-scale-amenable single step process of photonic curing which could be utilized to fabricate electrodes in industrial scale.

A multi-component synthetic route for 2-pyrazolines via acceptorless dehydrogenation of alcohols using homogeneous Ni(II) catalysts.

Herein, we present the first efficient and sustainable multicomponent synthesis (MCS) of 2-pyrazolines using acceptorless dehydrogenation of benzyl alcohols catalysed by nickel(II) catalysts. Two air-stable phosphine free nickel(II) complexes anchored by NNN-type pincer ligands were synthesized and efficiently used in the MCS of 40 distinct pyrazoline derivatives.

Dual functional materials based on Ni and different alkaline metals on alumina for the cyclic stepwise CO2 capture and methanation

Bimetallic catalysts consisting of nickel and one alkali or alkaline-earth metal (Na, K or Ba) on alumina support have been tested in the cyclic CO2 capture and subsequent methanation. The best performance was attained with a different material for cyclic tests (K-Ni/Al) than for Sabatier reaction (Ba-Ni/Al). In cyclic tests, the methane productivity shows different dependence with the temperature for each alkali and alkaline-earth metal. For temperature of 300 °C or above, the dual functional materials show stable cyclic performance when the capture is performed both from 5% CO2 in Ar and from simulated flue gas containing also O2 and H2O. Using the later feed, the CH4 productivity diminish reversibly compared to oxygen free conditions and nickel metal oxidises significantly. K-Ni/Al exhibited the best cyclic performance in terms of CH4 productivity and stability, which is associated to the highest reducibility of oxidised nickel species and the lowest formation of unreducible carbonates.

Chemical kinetics of two-step thermochemical decomposition of hydrogen sulfide over nickel sulfide

The study develops a multistep reaction mechanism for a two-step thermochemical cycle that produces hydrogen from H2S decomposition, using nickel sulfide as a catalyst. Two mechanisms were investigated: 1) a gas-phase mechanism that occurs without a Ni catalyst to determine the contribution of thermal decomposition to the overall reaction without a catalyst, and 2) a microkinetic model of the catalytic Ni surface phase to examine the key parameters affecting the overall cycling process and H2S conversion efficiency. Both mechanisms were validated using CHEMKIN-Pro software to analyze the experimental data and trends. The study showed that gas-phase H2S conversion was not kinetically significant below 850 °C. The microkinetic model showed that most H2S was transformed into H2 and NiS products when the sulfurization temperature reached 500 °C. Additionally, the site fraction of NiS decreased while the number of free active nickel sites increased as the regeneration temperature increased from 500 °C to 800 °C. A temperature limit of 700 °C was set for the regeneration step due to the agglomeration behavior of nickel sulfide particles.

Nickel-Passivating element selection in FCC process and mechanistic study on the passivation of nickel by lanthanum and phosphorus

Motivated by the dehydrogenation activity of nickel (Ni) and the toxicity of free nickel oxide (NiO) in the fluid catalytic cracking (FCC) catalysts, this study aims to reveal the appropriate elements to in-situ passivate nickel during the cracking reactions of oil by conducting hydrocarbon dehydrogenation tests of Y-zeolite loaded with Ni and passivating elements in a Pyro-probe micro-reactor coupled with GC-TCD and MS. The conditions were chosen as 550 °C with a catalyst-to-hydrocarbon mass ratio of 5:1. Additionally, hydrogen-temperature programmed reduction (H2-TPR) was conducted. In supporting the experimental observation, thermodynamic calculations were also performed to assist the selection of possible Ni-passivating elements in terms of the free Gibbs energy for their reactions with NiO. Lanthanum (La) and phosphorus (P) were found to exert the most effective effects on nickel passivation. The use of twice the quantity of La or P more than Ni, or the combined use of La and P each in equimolar ratio to Ni is able to decrease the dehydrogenation extent by 97%. La can passivate the free NiO species by chemically bonding with NiO which, otherwise, would bond with alumina in zeolite. Instead, P is preferentially coated on the Ni-bearing particles, which leads to the formation of phosphate that is inactive in the dehydrogenation of the model organic compounds when compared to the free NiO.

Understanding the Insight Mechanism of Chemical-Mechanical Degradation of Layered Co-Free Ni-Rich Cathode Materials: A Review.

Layered Cobalt (Co)-free Nickel (Ni)-rich cathode materials have attracted much attention due to their high energy density and low cost. Still, their further development is hampered by material instability caused by the chemical/mechanical degradation of the material. Although there are numerous doping and modification approaches to improve the stability of layered cathode materials, these approaches are still in the laboratory stage and require further research before commercial application. To fully exploit the potential of layered cathode materials, a more comprehensive theoretical understanding of the underlying issues is necessary, along with active exploration of previously unrevealed mechanisms. This paper presents the phase transition mechanism of Co-free Ni-rich cathode materials, the existing problems, and the state-of-the-art characterization tools employed to study the phase transition. The causes of crystal structure degradation, interfacial instability, and mechanical degradation are elaborated, from the material's crystal structure to its phase transition and atomic orbital splitting. By organizing and summarizing these mechanisms, this paper aims to establish connections among common research problems and to identify future research priorities, thereby facilitating the rapid development of Co-free Ni-rich materials.

Quantitative determination of nickel speciation for the presence of free oxide in commercial fluid catalytic cracking catalysts

Motivated by the potential over-catalysis and hazardousness of free nickel oxide (NiO) in the equilibrated catalysts (Ecats) collected from fluid catalytic cracking (FCC) refineries, this study aims to establish a simple bulk method, namely chemical leaching method to rapidly quantify the NiO content within thirteen commercial Ecats collected from different units. The synchrotron-–based, X–ray absorption near–edge structure (XANES) was performed to assess the validity of this method, as well as to examine the coordination structure of Ni by the extended X–ray absorption fine structure (EXAFS) analysis. Additionally, thermodynamics calculation was attempted to validate the affiliation of Ni with other metal oxides. The optimum leaching condition was validated as 60 °C in 60 min using 1 M sulfuric acid. Accordingly, the NiO was determined to reach 70–439 ppm in all Ecats, which warrants a non–hazardousness of these samples. Additionally, for the Ecats with a remarkably higher Ni content, the XANES results are biased by the enrichment of NiO on the catalyst surface. The majority of Ni was found to affiliate with Al in the form of aluminate, with the remaining 11%–15% Ni passivated effectively by lanthanum (La). The oxygen–rich regeneration condition could be beneficial for promoting the affiliation of Ni by La.

Molecular Structure of Nickel Octamethylporphyrin-Rare Experimental Evidence of a Ruffling Effect in Gas Phase.

The structure of a free nickel (II) octamethylporphyrin (NiOMP) molecule was determined for the first time through a combined gas-phase electron diffraction (GED) and mass spectrometry (MS) experiment, as well as through quantum chemical (QC) calculations. Density functional theory (DFT) calculations do not provide an unambiguous answer about the planarity or non-planar distortion of the NiOMP skeleton. The GED refinement in such cases is non-trivial. Several approaches to the inverse problem solution were used. The obtained results allow us to argue that the ruffling effect is manifested in the NiOMP molecule. The minimal critical distance between the central atom of the metal and nitrogen atoms of the coordination cavity that provokes ruffling distortion in metal porphyrins is about 1.96 Å.

Chlorophyll derivatives/MXene hybrids for photocatalytic hydrogen evolution: Dependence of performance on the central coordinating metals

Development of efficient photocatalytic hydrogen evolution reaction (HER) with illumination of visible light is challenging. In this work, five chlorophyll derivatives (M-Chls; M = H2/Cu/Ni/Co/Zn) with different central ions in its cyclic tetrapyrrole ring including free base, copper, nickel, cobalt, and zinc were synthesized and employed as the effective visible-light harvester for efficient HER. In addition, two-dimensional (2D) noble metal-free co-catalyst Ti3C2Tx MXene was used as an excellent electron capturer due to its outstanding conductivity property. These M-Chls are modified on the surface of Ti3C2Tx MXene with 2D accordion-like morphology by means of a simple deposition process to form noble metal-free Chl/Ti3C2Tx-based photocatalysts for HER. It is found that the best HER performance as high as 49 μmol/h/gcat was achieved with the Co-Chl@Ti3C2Tx hybrid, which was much higher than those of other M-Chl@Ti3C2Tx composites. This research provides a specific way to synthesize low-cost and environmentally friendly natural Chls for developing highly efficient photocatalytic HER through molecular engineering.

Increasing of the corrosion resistance by preparing the trivalent nickel complex

This paper is intended to investigate the preparation of a complex ion Ni chloride (II) and with ligand Schiff base (N, N) dimethyl of the amino Benzaldhyde and characterized ligand prepared and complexion Ni chloride(II). These metallic organic chemical compounds have been checked using Spectroscopic Techniques Spectrums of infrared and spectra of UV. The study included a test of the Corrosion Rate of free matter and nickel complex in tap water solution in a linear polarization method By the linear polarization curves resulting from Tafel device readings. The results showed that the nickel complex has an effective inhibitory effect due to the low current value, which increases its corrosion resistance.

Template and binder free 1D cobalt nickel hydrogen phosphate electrode materials for supercapacitor application

Herein, we synthesized 1D bimetallic hydrogen phosphate [CoxNix(HPO4)] nanorods by using a simple and effective chemical bath deposition method for supercapacitor applications. The prepared CoxNix(HPO4) was analyzed by Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) pattern. The surface morphology was envisaged by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. The porous nature and surface area of the materials were characterized by nitrogen sorption isotherm and a high specific surface area of 153 m2 g−1 was found to be for Co0.75Ni0.25(HPO4). The Co0.75Ni0.25(HPO4) displays a maximum specific capacity of 475 mA h g−1 at 1 A g−1 in a three-electrode configuration using 3 M KOH as the electrolyte. Co0.75Ni0.25(HPO4) exhibits almost 94.8% of its initial specific capacity over 5000 GCD cycles at 10 A g−1. Furthermore, the fabricated asymmetric supercapacitor (ASC) with Co0.75Ni0.25(HPO4) and activated carbon (AC) showed a high specific capacitance of 182.5F g−1 at 0.5 A g−1. The ASC device delivered a maximum energy density of 64.88 Wh kg−1 at a power density of 800 W kg−1.

Simultaneous electrochemical deposition of nickel cobalt oxide-reduced graphene oxide composites for high performance asymmetric supercapacitors

In this work, a one-step electrodeposition approach was applied for nanosheets fabrication of binder free nickel cobalt oxide (NCO) and NCO-reduced graphene oxide (NCO-rGO) composites on the nickel-foam substrate by repetitive cyclic voltammetry (rCV). The NCO-rGO hybrids were firstly fabricated on Ni foam surface with the reduction of GO and electrodeposition of NCO simultaneously. Interaction of NCO particles with rGO sheets increased the conductivity of the composite and consequently facilitated the electron transfer rate. Electrochemical measurements proved that specific capacitance and cyclic performance of as-prepared materials were improved with the synergistic effect of rGO in the hybrid structure. The optimized NCO-rGO electrode exhibited a specific capacitance of 1916.5 F g−1 at 1 A g−1 with superior stability of 95.6% at a high current density of 10 A g−1 even after 3000 cycles. To explore its practical applications, an asymmetric supercapacitor (ASC) based on NCO-rGO as a positive electrode and rGO as a negative electrode was constructed, which exhibited a prominent specific energy of 45.22 Wh kg−1 at 400 W kg−1. As a result, NCO-rGO hybrid structure as the functional electrode material for the supercapacitors with remarkable electrochemical performance were obtained, thanks to the increased conductivity and decreased mass by removing binders.

Electrochemical Ni-EDTA degradation and Ni removal from electroless plating wastewaters using an innovative Ni-doped PbO2 anode: Optimization and mechanism

In this work, a novel Ni-doped PbO2 anode (Ni-PbO2) was prepared via a co-electrodeposition method and used to remove Ni-ethylenediaminetetraacetic acid (Ni-EDTA) from solutions typical of electroless nickel plating wastewater. Compared with a pure PbO2 electrode, Ni doping increased the oxygen evolution potential as well as the reactive surface area and reactive site concentration and reduced the electron transfer resistance thereby resulting in superior Ni-EDTA degradation performance. The 1% Ni-doped PbO2 electrode exhibited the best electrochemical oxidation activity with a Ni-EDTA removal efficiency of 96.5 ± 1.2%, a Ni removal efficiency of 52.1 ± 1.4% and an energy consumption of 2.6 kWh m−3. Further investigations revealed that 1% Ni doping enhanced both direct oxidation and hydroxyl radical mediated oxidation processes involved in Ni-EDTA degradation. A mechanism for Ni-EDTA degradation is proposed based on the identified products. The free nickel ion concentration initially increased as a result of the degradation of Ni-EDTA complexes and subsequently decreased as a consequence of nickel electrodeposition on the cathode surface. Further characterization of the cathode deposits by X-ray diffraction and X-ray photoelectron spectra indicated that the deposition products were a mixture of Ni0, NiO and Ni(OH)2 with elemental Ni accounting for roughly 80% of the deposited nickel. Results of this study pave the way for the application of anodic oxidation processes for efficient degradation of Ni-containing complexes and recovery of Ni from nickel-containing wastewaters.

Study of pulse electrodeposition parameters for nano YSZ-Ni coatings and its effect on tribological and corrosion characteristics

In the present work, the surface properties of EN8 steel with/without pulse electrodeposition have been investigated. The co-deposition of nano-sized Yttria Stabilized Zirconia (YSZ; ≈ 80 nm average diameter) has been done using additive—free nickel solution by applying the pulse current. The deposition of YSZ-Ni metal matrix composite (MMC) was obtained by varying the duty cycle (D.C.; i.e. 30 and 50%) and maintaining a constant frequency of 10 Hz. The current density also varied between 0.02 and 0.06 A/cm2 and optimized on the basis of improvement of surface characteristics and defect-free deposits. Penetration strength of the composite coated surface has been investigated with the nanoindentation test. A significant difference in the surface hardness was observed by varying the duty cycles and current densities. Corrosion test has been performed to estimate the corrosion rate of the coated surfaces. And, it observed approximately one-fourth times reduction in corrosion rate for MMC electrocoating at the optimum condition as compared to the base substrate. In addition, the adherence quality and antiwear performance of different coated substrates evaluated with reciprocating test rig. A substantial improvement in antiwear performance for composite coatings has been reported. Different analytical tools have been used to characterize the composite surfaces. Also, the effects of various process controlling parameters and corresponding analysis have been reported.

Methanol Sensing using Catalyst Free Nickel Foam Modified with Solvo-thermally Synthesized Magnetite (Fe3O4) Nanoparticles

Methanol Sensing using Catalyst Free Nickel Foam Modified with Solvo-thermally Synthesized Magnetite (Fe3O4) Nanoparticles

Binder free high performance hybrid supercapacitor device based on nickel ferrite nanoparticles

Abstract In this study, we present the actual electrochemical performance of a highly stable hybrid supercapacitor device based on faradic type binder free nickel ferrite (NiFe2O4) positive electrode and activated carbon negative electrode. NiFe2O4 nanoparticles are directly grown over the Ni-foam and stainless steel substrates by a scalable and novel surfactant assisted co-precipitation technique. The structural and morphological properties of the NiFe2O4 nanoparticles are investigated by using different characterization techniques. The electrochemical performance is investigated in 6 M aqueous KOH electrolyte using cyclic voltammetry and galvanostatic charge-discharge techniques. Ni-foam/NiFe2O4 positive electrode exhibits specific capacity of 398 C/g at 1 A/g current density which is much higher than the stainless steel /NiFe2O4 positive electrodes and can be attributed to the better interfacial bonding between Ni-foam and NiFe2O4 nanoparticles and formation of a concomitant 3D porous architecture. A maximum specific energy of 27.71 Wh/kg and specific power of 14.49 kW/kg are achieved at 1 and 20 A/g current density in the hybrid supercapacitor device fabricated utilizing the Ni-foam/ NiFe2O4 positive and activated carbon negetive electrodes. Moreover, the device shows ~98% retention of its specific capacity after 6500 cycles at 5 A/g current density which reveals superiority of NiFe2O4 as an electrode material for supercapacitor application.

Corrosion resistance of a Nitinol ocular microstent: Implications on biocompatibility.

Nitinol is commonly used in medical implants due to its unique thermomechanical properties of shape memory and superelasticity. Free nickel has the potential to induce biological responses that may be a concern for permanent implants manufactured from nickel-containing alloys. Although there are extensive reports on the effects of surface treatments on corrosion behavior in cardiovascular Nitinol implants, there is a lack of data on corrosion resistance and impact on biocompatibility for ocular implants. Therefore, the objective of this study was to determine localized corrosion and nickel elution resistance of an electropolished Nitinol-based ocular device (Hydrus Microstent, Ivantis, Inc.) intended for patients with primary open angle glaucoma. Pitting corrosion susceptibility was characterized by potentiodynamic polarization testing per ASTM F2129. In addition, nickel ion release was quantified with immersion testing to 63 days. The results indicated high localized corrosion resistance as all samples reached polarization potentials of 800 mV without pitting initiation. Maximum nickel elution rates per device were less than approximately 1.1 ng/device/day after the first day of immersion and reduced to less than 0.1 ng/device/day after 7 days. For a patient with bilateral microstents, these nickel concentrations are ×10,000 lower than previously published tolerable intake levels for systemic toxicity. Overall, these corrosion results are in good agreement with literature values of well processed and biocompatible Nitinol devices indicating adverse systemic biological responses are not expected in vivo.

Large scale epitaxial graphite grown on twin free nickel(111)/spinel substrate

Large scale, single crystalline graphite with millimeter size domain is achieved using a LPCVD process with a temperature below 925 °C.

Facile synthesis of nickel cobalt sulfide nano flowers for high performance supercapacitor applications

A facile synthesis of nickel cobalt sulfide (NCS) nanoflowers have been deposited successfully onto binder free 3D nickel foam electrodes using simple successive ionic layer adsorption and reaction (SILAR) method for supercapacitor applications. The obtained NCS nanoflowers manifest ultrahigh specific capacitance of 1899 F g−1 at a scan rate of 5 mV s−1. The NCS nanoflowers exhibit a prominent energy density of 55.16 Wh kg−1 at power density of 495 W kg−1 and superior cyclic stability of 94% after 10000 cycles. In addition, the asymmetric supercapacitor (ASC) device is fabricated using NCS nanoflower as positive and reduced graphene oxide (rGO) as negative electrodes, respectively. The ASC (NCS//rGO) delivered good capacity with excellent energy and power densities within 1.6 V wider potential window. Hence, NCS nanoflowers are an outstanding material for energy storage applications in near future.

Validation of a combined Fe(III)/UV/NaOH process for efficient removal of carboxyl complexed Ni from synthetic and authentic effluents

Nickel, massively used in plating industry but detrimental to ecosystem, tends to form stable complexes with organic additives in industrial effluents. Currently, most of the available processes aim at water decontamination from free toxic metal ions and thus, could not effectively remove nickel-carboxyl complexes from water. Herein, we employed a proprietary combined process Fe(III)/UV/NaOH, namely Fe(III) displacement and UV irradiation followed by alkaline precipitation, to validate its feasibility on the efficient removal of nickel-carboxyl complexes from synthetic and authentic effluents. Fe(III)/UV/NaOH outperformed other commonly used processes including NaOH precipitation, UV/NaOH, Fe(III) coagulation, and Fenton/NaOH. Each unit of the combined process was optimized, and the underlying mechanism was elucidated. Fe(III) displacement favored the stoichiometric release of free nickel ions and formation of Fe(III)-carboxyl complexes, which could be decarboxylated via ligand-metal charge transfer under UV irradiation. The precipitation unit aims at simultaneously removing the released Ni along with Fe species. Attractively, the presence of other organic species (ethylene glycol, ethyl acetate and humic acid) and anions (chloride and sulfate) exerted very slight effect on the final Ni removal, whereas greatly adverse effect occurred on the Fenton process under similar conditions. The feasibility of the combined process was validated by testing on an authentic electroplating effluent, resulting in the residual Ni below 0.1 mg/L, the most stringent discharge standard for Ni in electroplating effluent in China.