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Zinc–nickel coatings based on the zinc-enriched gamma phase exhibit the maximum corrosion resistance and form the basis of the production of highly electrocatalytically active nanoporous nickel by selective dissolution. The electrodeposition of Zn–Ni alloys is the most widely used method of their preparation which proceeds by the mechanism of anomalous codeposition, where the deposition rate of the electropositive component (nickel) is lower as compared with the electronegative component (zinc). To obtain coatings of the particular morphology, chemical and phase composition, it is necessary to know the kinetics of the cathodic deposition of Zn–Ni alloys in the stage of heterogeneous nucleation, which is the goal of this study. The kinetics of this process is studied in non-stirred ammonium chloride electrolytes using the methods of cyclic voltammetry and chronoamperometry. The mechanism of heterogeneous nucleation at the electrodeposition of zinc and nickel is determined using the approach proposed by Palomar-Pardavé et. al which takes into account the contributions to the total cathodic current made by the parallel reaction of hydrogen reduction and the electric double layer charging. The nucleation mechanism for zinc–nickel coatings is described using the model of Scharifker–Hills for the electrodeposition of binary alloys additionally modified by taking into account the experimentally determined dependence of the composition of zinc–nickel coatings on the time in the stage of cathodic nucleation of the deposit. Using the method of energy-dispersive X-ray spectroscopy, the anomalous character of the deposition of Zn–Ni coatings is confirmed, where the ratio of atomic fractions Ni/Zn turns out to be lower than the ratio of concentrations of ions Ni2+/Zn2+ in the electrolyte. It is found that both during the electrodeposition of zinc and nickel from their individual solutions and during their anomalous codeposition, the nucleation rate constant increases with an increase in the cathodic potential but in average does not exceed 3 s–1, which points to the predominantly progressive nucleation. The growth of the new phase, regardless of its chemical composition, is limited by the 3D-diffusion of zinc and nickel ions to the electrode surface. The nucleation site density depends weakly on the deposition potential, decreasing with the transition from zinc to nickel and zinc–nickel alloys. As expected, the contribution of the side reaction of hydrogen reduction is the maximum for nickel electrocrystallization and decreases with the transition to Zn–Ni alloys and zinc, increasing with an increase in the cathodic potential, in agreement with the values of current efficiency. [ABSTRACT FROM AUTHOR]

We present a unique, one‐step, hydrothermal process to prepare nickel sulfide (Ni3S2) foam by a simple and direct conversion from nickel foam, which contributes both as a scaffold for the reaction and as reactant. The Ni3S2 foam exhibits remarkable mechanical stability, retaining the structural integrity of the foam and excellent crystallinity even after ultrasonication at 200 W for 30 mins. We document the transformation of the nickel foam template into a Ni3S2 foam, highlighting the role of synthesis duration on the phase evolution and unique morphology of Ni3S2. PXRD and SEM analyses reveal a complete transformation after 24 hours from the nickel foam to a pure Ni3S2 foam, which has a highly porous and interconnected ultra‐thin nanosheet architecture. This significantly enhances the surface area and provides many electrochemical reaction sites. In a three‐electrode cell, the capacity of the Ni3S2 foam electrode is 3.9 C cm−2 at 8 mA cm−2, which is higher than previous reports for Ni3S2. In a hybrid supercapacitor device, the Ni3S2 foam demonstrates significant increase in capacitance through 500 cycles and the capacitance plateaus after 2000 cycles. Even after 8500 continued charge‐discharge cycles, the device exhibits excellent cycle stability indicating improvement with age. [ABSTRACT FROM AUTHOR]

Gluconic acid and sorbitol are among the value-added chemicals that can be derived from biomass. Nowadays, these compounds are typically produced through biotechnological processes, but electrochemical methods offer numerous advantages over alternative approaches. While studies have extensively explored metals like copper, palladium, gold, and platinum, nickel has received relatively limited attention in this context. Notably, nickel exhibits electrochemical activity suitable for organic electrosynthesis. This work has been achieved with 5-h long-term electrolysis, glucose as a reactant, utilizing modified nickel electrodes in a KOH solution. While these studies achieved substantial conversion rates, the selectivities and Faraday efficiencies toward gluconic acid and sorbitol remained comparatively low. The long-term electrolysis of glucose using modified nickel electrodes resulted in the identification of various side products. These include formic acid, oxalic acid, glycolic acid, tartronic acid, glyceric acid, and arabinose. [ABSTRACT FROM AUTHOR]

Electrochemical catalysis emerges as a promising method for lignin depolymerization due to its environmental friendliness and mild reaction condition. Metal oxyhydroxides have displayed appealing electrochemical activity for the oxidation for various biomass substrates. In this study, we prepared different metal (Ni, Co, Mn, Fe, and Cu) oxyhydroxides on nickel foam electrodes through electrodeposition. Their electrochemical properties were characterized and the reactivity towards lignin oxidative cleavage was investigated using lignin model compounds. NiOOH exhibited significantly higher activity for oxidative cleavage of the β-O-4 linkage compared to other metal oxyhydroxides, resulting in a 93% yield of aromatic monomers with 99% selectivity towards benzoic acids. Furthermore, the reconstruction process of the active site NiOOH was revealed by in-situ testing, and the reaction mechanism was explored. The non-phenolic structure underwent Cβ–Cγ/Cβ–O or Cα–Cβ cleavage, predominantly producing benzoic acids, while the phenolic structure was rapidly oxidized into dicarboxylic acids over NiOOH. [ABSTRACT FROM AUTHOR]

This work presents studies to study the nucleation and growth mechanism of electrochemical NiMo films suitable for the decomposition reaction of water as an electrocatalyst, in which the value of the potential established from polarization measurements was maintained constant. Optimal conditions for the electrochemical synthesis of the Ni-Mo alloy on the surface of platinum and nickel electrodes were established using voltammetric studies examining the influence of many electrolysis parameters on the process of co-deposition of nickel with molybdenum. The chronoamperometric method provides more detailed information about the electrodeposition process by studying the nucleation and growth mechanism of electrochemical films in which the potential value determined from polarization measurements was kept constant. The curves were taken at various potential values -0.1, -0.2, -0.3, -0.4, -0.5, -0.6, -0.7, -0.8 and -0.9 V at room temperature. The study of these curves can be carried out by comparing the experimental calculated data with the equations of the Scharifker-Hills model. It was found that in the early stage, at potentials of -0.1 and -0.2 V, the experimental data fit into the curve of the progressive nucleation model, according to which Ni-Mo nucleation occurs on many active areas of the substrate surface, but at other potentials (from -0.3 to -0.9 V) deposition deviates towards instantaneous nucleation and growth. [ABSTRACT FROM AUTHOR]

An attempt was made, at the laboratory level, to apply new external anode of an electrochemical chloride extraction (ECE) system based on Ni chemical deposition on concrete specimen surface. The procedure relied on electroless bath chemical deposition to apply anodic electrode of nickel on concrete samples. The procedures and experimental conditions of the nickel deposition on the concrete were carefully addressed. The influence of Ni films characteristics, as external anode in ECE system, on the chloride electrochemical extraction (ECE) process was investigated. ECE performance in comparison with the use of traditional titanium mesh was investigated. Several analytical tools were applied to both characterise the obtained Ni films and to study the efficiency of ECE process. These include scanning electron microscopy (SEM) to explore the morphology of the nickel films and the electron probe micro analysis (EPMA) that was performed simultaneously with SIM to gain composition analysis of the samples. Finally, chloride ion selective electrode (ISE) analytical tool was applied to study the efficiency of ECE process. [ABSTRACT FROM AUTHOR]

The significant amount of gas bubbles generated during high‐rate alkaline water splitting (AWS) can be detrimental to the process. The accumulation of bubbles will block the active catalytic sites and hinder the ion and electrolyte diffusion, limiting the maximum current density. Furthermore, the detachment of large bubbles can also damage the electrode's surface layer. Here, a general strategy for facilitating bubble detachment is demonstrated by modifying the nickel electrode surface with nickel nanocone nanostructures, which turns the surface into underwater superaerophobic. Simulation and experimental data show that bubbles take a considerably shorter time to detach from the nanocone‐modified nickel foil than the unmodified foil. As a result, these bubbles also have a smaller detachment size and less chance for bubble coalescence. The nanocone‐modified electrodes, including nickel foil, nickel foam, and 3D‐printed nickel lattice, all show substantially reduced overpotentials at 1000 mA cm−2 compared to their pristine counterpart. The electrolyzer assembled with two nanocone‐modified nickel lattice electrodes retains >95% of the performance after testing at ≈900 mA cm−2 for 100 h. The surface NC structure is also well preserved. The findings offer an exciting and simple strategy for enhancing the bubble detachment and, thus, the electrode activity for high‐rate AWS. [ABSTRACT FROM AUTHOR]

Nickel (Ni) is an essential resource in many industries. However, as the industrial use of Ni increases, its impact as an environmental pollutant has also increased. Accordingly, effective Ni treatment processes are required. In this study, hybrid capacitive deionization (HCDI) with an Ag-coated activated carbon (AC) electrode was proposed as a Ni treatment. The deionization capacity of the HCDI system with Ag coating was 66% higher than that of the membrane capacitive deionization system. In addition, as the applied potential increased from 0.5 V to 1.1 V, the deionization capacity also increased from 10 mg/g to 18 mg/g, although the charge efficiency decreased from 84.6% to 77.2%. However, when the applied potential was 0.9 V or more, the pH of the effluent exceeded the drinking water range, which appeared to be caused by the electron transfer reaction of Ni ions under a high applied potential (0.9 V or more). In terms of energy consumption, HCDI with Ag-coated electrodes achieved 0.24 Wh/g-NiCl2 as a minimum value. The results of this study demonstrate the potential of capacitive deionization (CDI) for Ni treatment. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of dysprosium ions, as well as dysprosium and nickel ion co-reduction, on inert tungsten electrodes and active nickel electrodes were studied in the eutectic KCl-NaCl-CsCl melt at a temperature of 823 K using the methods of cyclic and square-wave voltammetry and open circuit chronopotentiometry. The process of Dy3+ ions electroreduction was found to be reversible and to proceed within a single three-electron stage up to the polarization rate of 0.1 V/s. The increase in the polarization rate indicates a slower rate of the charge transfer, which causes the quasi-reversible character of the charge transfer. It is shown that when the KCl-NaCl-CsCl eutectic melt contains both nickel and dysprosium ions, the voltammetry curves at 823 K have a wave of nickel ion reduction at the potentials of −(0.22–0.28) V and a dysprosium ion reduction at the potentials of −(2.175–2.250) V relative to a chlorine-silver reference electrode. Apart from these waves, the voltammograms have two reduction waves at the potentials of −(1.9–1.95) V and −(2.05–2.1) V. These waves are associated with the reduction of dysprosium ions and their depolarization on metallic nickel, which was preliminary deposited on the tungsten electrode, as well as the formation of the intermetallic phases of dysprosium and nickel of various DyxNiy compositions. The (E-t) dependencies of the open circuit chronopotentiometry elucidate plateaus of the potential delay, which correspond to the dissolution of separate dysprosium and nickel intermetallic phases. Based on the results of the voltammetry changes and the chronopotentiometry of the open circuit, a series of electrochemical syntheses were performed in the potentiostatic regime at the potentials of −(1.7–2.1) V. The intermetallic phases of DyNi5, DyNi3 and DyNi2 were obtained at a definite ratio of the dysprosium and nickel chloride concentrations in the KCl-NaCl-CsCl eutectic melt and at a temperature of 823 K. The synthesized intermetallic samples were characterized by X-ray diffraction and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

In this work, Silver Nanoparticles/Bismuth Oxybromide (AgNP/BiOBr) was prepared and drop casted on a graphite electrode to sense nickel ions present in aqueous matrix. The sensing behavior of the modified graphite electrode towards nickel ions was experimented using cyclic voltammetry (CV) technique. The material structure, surface morphology, functional groups and elemental composition of the synthesized AgNP/BiOBr were analyzed by X-ray diffraction study (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Fourier Transform-Infra red spectroscopy (FTIR) and Energy Dispersive Spectroscopy (EDX Spectrum) respectively. The proposed electrode showed superior electrochemical performance for nickel ions detection at a pH of 11. A linear current response was observed for a nickel concentration range of 0–0.8 ppm. In addition, the nanomaterial exhibits selective adsorption capability towards nickel ions in the presence of other metal ions such as copper, zinc and iron. The limit of detection (LOD) and the limit of quantification (LOQ) of the proposed electrochemical sensor were found to be 0.0072 ppm and 0.025 ppm, respectively. The proposed sensor showed a sensitivity of 0.298 µA/ppb and a correlation coefficient (R2) value of 0.98. The obtained results for the proposed sensor signify its suitability for the detection of nickel ions with high sensitivity. [ABSTRACT FROM AUTHOR]

This study consists in the determination of two kinetic laws of urea oxidation (UO) and electrooxidation (UEO) in alkaline media on nickel(III). Two kinds of active sites were examined, the first one derived from a Ni(OH)2 powder and the second from a massive nickel electrode. Partial orders of nickel(III) (two for UO and five UEO) enable to conclude about (i) the urea adsorption on two nickel(III) sites and (ii) that a multistep oxidation of urea occurs involving five nickel(III) site electroregenerations. A multipathway mechanism is also proposed to explain UEO facilitated by the nickel(III)/nickel(II) mediation system, and to predict the by‐products' formation previously identified (NO2−,NH3,OCN−,CO32−). At last, a model combining the UEO kinetic law previously established, with diffusive and convective transport phenomena was developed. A consistent correlation (maximum deviation of 6%) between laboratory electrolysis results with the model' predictions was obtained under different operating conditions, enabling the validation of this model. [ABSTRACT FROM AUTHOR]

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The salt of formula [H2EDTA2+][HSO4−]2 (dihydrogen ethylenediaminetetraacetate di(hydrogen sulfate(VI)) was used to examine the physicochemical properties of the resulting Ni layer and evaluate the applicability of the salt as a new additive for Watts-type baths. The Ni coatings deposited from baths containing [H2EDTA2+][HSO4−]2 were compared with those obtained from other baths. The nucleation of nickel on the electrode was proven to occur the slowest in the bath that contained the mixture of [H2EDTA2+][HSO4−]2 and saccharin compared with other baths. The addition of [H2EDTA2+][HSO4−]2 alone (bath III) generated a coating with a morphology similar to that obtained from bath I (without additives). Despite the similar morphology and wettability of the Ni-coated surfaces plated from various baths (all Ni coatings were hydrophilic with contact angles in the range of 68 to 77°), some differences in electrochemical properties were noted. The corrosion resistance for the coatings plated from baths II and IV containing saccharin (Icorr = 1.1 and 1.5 µA/cm2, respectively) and the mixture of saccharin and [H2EDTA2+][HSO4−]2 (Icorr = 0.88 µA/cm2), respectively, was similar or even better than the coating obtained from baths without [H2EDTA2+][HSO4−]2 (Icorr = 9.02 µA/cm2). [ABSTRACT FROM AUTHOR]

Nickel foam substrates are frequently utilised as porous 3D substrates for renewable energy applications. The preparation of these substrates usually includes an acid-washing step, but the degree to which this step affects the final electrochemical performance after spray-coating a catalyst ink is unreported. Herein, we report the effects of acid washing through physicochemical and electrochemical characterisation. The electrochemical performance was determined through repeated measurements of catalyst-coated nickel foam substrates both with and without the initial step of acid washing. It was found that acid washing increased the current density by 17.9% for the acid-treated MoS2-coated nickel foam electrode. This increment was affiliated with an electrochemically active surface area that increased by 11.2%, and a Tafel analysis indicated that the acid-treated MoS2-coated electrodes facilitated the initial water dissociation step of the hydrogen evolution reaction with greater ease. Similar effects were also discovered for acid-treated PtIr(1:3)/C-coated nickel foam substrates. The stability was also improved; the degradation rate was reduced by 18.9% for the acid-treated MoS2-coated electrodes. This demonstrates the utility of acid washing nickel foam electrodes. [ABSTRACT FROM AUTHOR]

Abstract—The state of the surface of a nickel electrode in weakly alkaline medium is studied with the electrochemical impedance-frequency spectroscopy method. An equivalent electrical circuit of the processes that proceed under these conditions is proposed, which describes these processes and the ratings of the elements of the electrical circuit. [ABSTRACT FROM AUTHOR]

Nickel foam is widely used as a current lead/ current collector and as the base of nickel hydroxide electrodes for hybrid supercapacitors. An investigation of the influence of activation conditions for a commercial sample of nickel foam produced by Linyi Gelon LIB Co Ltd (China) was carried out using the method of impact nickel plating. The morphology of activated and non-activated nickel foam samples was investigated by scanning electron microscopy. Activated and non-activated nickel foam samples were investigated by methods of cyclic voltammetry and galvanostatic charge-discharge cycling in the supercapacitor mode. It was shown that upon activation at i=1 A/dm² and τ=10 min, a thin layer of porous nickel with incomplete coverage was formed. Activation with impact nickel at i=7 A/dm² and τ=3 min revealed the formation of a nickel coating with a highly developed surface, on which local cracks were found as a result of the accumulation of internal stresses. Activation with impact nickel at i=1 A/dm² and τ=10 min led to the formation of a coating with a highly developed surface, with significant peeling of the coating. Cyclic voltammetry showed high efficiency of impact nickel activation at i=7 A/dm², τ=3 min, and i=20 A/dm², τ=5 min. The specific current of the cathode peak increased 6.06–6.44 times with respect to the non-activated sample. The investigation of the activated samples’ electrochemical characteristics by the galvanostatic cycling method showed that impact nickel activation at i=1 A/dm² and τ=10 min was insufficient. It was found that at a discharge up to E=0 V, the maximum specific capacitance of 0.731 F/cm² was obtained for samples activated by impact nickel at i=7 A/dm² and τ=3 min. The increase in specific capacitance compared to the non-activated sample was 4.49 times. At full discharge, the highest electrochemical activity was found for nickel foam samples activated by impact nickel at i=20 A/dm² and τ=5 min. The specific capacitance was 0.505 mA∙h/cm², and it increased 9.02 times. [ABSTRACT FROM AUTHOR]

• Modifying Ni with Rh improves HER/HOR and ORR/OER kinetics in alkaline media. • Oxidation of the Rh-modified electrode has a negative impact on HER activity. • HER is faster, while HOR is slower on Rh-modified electrodes compared to pt. • OER activity of the Rh-modified electrode is high, while ORR kinetics is slower compared to pt. • Slow Rh-oxide reduction and insulating nature of Rh 2 O 3 are responsible for slower HOR and ORR kinetics. Developing novel electrocatalysts for energy conversion applications is of utmost importance for reaching the energy security of modern society. Here we present a comprehensive investigation of rhodium-modified polycrystalline nickel as an electrocatalyst for hydrogen and oxygen electrode reactions in alkaline media. The surface modification of nickel electrodes was achieved by facile galvanic displacement (up to 30 s) from a highly concentrated acidic Rh3+ solution. The results demonstrate a significant enhancement in the electrocatalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on the Rh-modified Ni electrodes, positioning galvanic displacement as a viable approach to engineering advanced electrocatalysts for clean energy applications. On the other hand, the hydrogen oxidation (HOR) and oxygen reduction reaction (ORR) activities of the Rh-modified electrodes are lower compared to polycrystalline platinum. It is suggested that semiconducting Rh 2 O 3 has a detrimental role on the HOR and ORR performance, while the activities of HER and OER, dominantly taking place on metallic Rh and conductive RhO 2 , are very high. This research sheds light on the mechanisms underlying the enhanced electrode kinetics on Rh-modified Ni electrodes and provides insights into the development of efficient and cost-effective electrocatalysts for renewable energy technologies. [Display omitted] [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) and the value‐added oxidation of renewable organic substrates are critical to supply electrons and protons for the synthesis of sustainable fuels. To meet industrial requirements, new methods for a simple, fast, environmental‐friendly and cheap synthesis of robust, self‐supported and high surface area electrodes are required. Herein, a novel in‐liquid plasma (plasma electrolysis) approach for the growth of hierarchical nanostructures on nickel foam is reported on. Under morphology retention, iron can be doped into this high surface area electrode. For the oxidation of 5‐(hydroxymethyl)furfural and benzyl alcohol, the iron‐free, plasma‐treated electrode is more suitable reaching current densities up to 800 mA cm−2 with Faradaic efficiencies above 95%. For the OER, the iron‐doped nickel foam electrode reaches the industrially relevant current density of 500 mA cm−2 at 1.473 ± 0.013 VRHE (60 °C) and shows no activity decrease over 140 h. The different effects of iron doping are rationalized using methanol probing and in situ Raman spectroscopy. Furthermore, the intrinsic activity is separated from the number of active sites, and, for the organic oxidation reactions, diffusion limitations are revealed. The authors anticipate that the plasma modified nickel foam will be suitable for various (electro)catalytic processes. [ABSTRACT FROM AUTHOR]

In this study, Ni, NiFe, and Pt are electrochemically deposited on the porous carbon felt for various periods to increase catalytic efficiency and hydrogen gas production, which is investigated in an alkaline medium. The prepared electrodes are characterized by using electrochemical impedance spectroscopy, linear sweep voltammetry, potentiodynamic polarization, cyclic voltammetry, scanning electron microscopy, and X-ray diffraction methods. In addition, hydrogen gas volume is measured by applying the electrolysis process to the electrodes prepared in 1.0 M KOH. It is observed that the most effective Ni deposition time on carbon felt is 20 min. Nickel deposited electrodes were coated with Ni&Fe and Pt in different periods to increase the catalytic effect of the electrode. The highest catalytic effect on the hydrogen evolution reaction was obtained from the C#Ni 20 NiFe 10 @Pt 45 electrode. Applied of a −0.2 V SHE overpotential, 80 mA cm−2 current density is obtained. The mechanism is determined as Volmer-Heyrovsky and rate determined step is Volmer. [Display omitted] • C felt was decorated with Ni, Fe, and Pt metals to investigate HER efficiency. • Electrocatalytic properties of electrodes analyzed by polarization technique. • Catalyst efficiency was characterized by using LSV, CV and EIS techniques. • Hydrogen production amount per square meter was determined. • The surface morphology was brightened with SEM and XRD techniques. [ABSTRACT FROM AUTHOR]

This study reports nickel removing by electrocoagulation of Ni(II)-NH3-CO2-SO2-H2O system at laboratory scale. Experiments were done using Al/Al pair electrodes at initial nickel concentration between 293 and 1356 mg L-1 and under operation parameters of pH 8.6, current density 9.8 mA cm-2, electrolysis time 30 min, and temperature 60 °C. The obtained results show removal efficiencies between 97.7 and 99.7%. Kinetics modeling suggested combined effects of external diffusion and nucleation, and as controlling step the chemical reaction and a possible autocatalytic contribution. The process followed the Langmuir's isotherm with a maximum adsorption capacity of 7519 mg g-1. ICP-OES, XRD and FTIR characterization of the precipitates indicated a typical Ni-Al layered double hydroxide structures with 33.4-40.7% nickel and 6.3-7.0% aluminum depending on initial nickel concentration. The operation costs of energy and electrode consumption were 320-537 $ t-1 of removed nickel. [ABSTRACT FROM AUTHOR]

The utilization of urea during electrolysis presents an appealing option for anodic oxidation, offering environmental benefits by converting waste into energy. The present work focuses on synthesizing mixed transition metal oxide (MMO) nanostructures composed of nickel rich nickel cobaltite electrode materials. Interesting, cobalt rich nickel cobaltite have been widely studied; however, the nickel-rich nickel cobaltite remains relatively unexplored. For stabilization of nickel rich nickel cobaltite, we have designed a process for synthesizing three-dimensional (3D) Ni-Co oxalate as a precursor via the coprecipitation method using diammonium oxalate monohydrate as a precipitating agent. The as obtained precursor was further subjected to thermal decomposition which results in the formation of Ni 2 CoO 4. Microstructural analysis of Ni-Co oxalate indicates that oxalate-assisted synthesis leads to anisotropic ultrafine nanoparticle growth, forming hierarchically arranged 3D microflowers. Interestingly, the use of NaOH as a precipitating agent induces a significant change in the morphology of Ni 2 CoO 4 , (nanoparticles). Furthermore, the effect of morphology changes over the electrochemical performance was investigated. Ni 2 CoO 4 microflower demonstrates an overpotential of 330 mV@25 mA/cm2 for O 2 and −190 mV@10 mA/cm2 for H 2 production during water oxidation in 1 M KOH, exhibiting excellent stability for up to 24 h. During urea oxidation, the potential required by Ni 2 CoO 4 microflowers was 1.31 V@10 mA/cm2. Ni 2 CoO 4 nanoparticles' performance is significantly poor during water and urea oxidation compared to the microflower counterpart. Therefore, this work provides detailed insights into designing MMOs with high porosity, increased exposed active sites, and unique structural features that enhance electrocatalytic activity. [Display omitted] • Coprecipitation method results in nickel-rich nickel cobaltite (Ni 2 CoO 4) formation. • Oxalate-route led to anisotropic nanoparticle growth to form 3D Ni 2 CoO 4 microflower. • Varying Ni: Co content during synthesis results in a notable change in morphology. • Ni 2 CoO 4 exhibits η of 330 mV@25 mA/cm2 for O 2 , −190 mV@10 mA/cm2 for H 2 in 1 M KOH. • Lower potential to 1.29 V@10 mA/cm2 during urea oxidation compared to bare KOH. [ABSTRACT FROM AUTHOR]

Revealing the gas-liquid interfacial corrosion mechanism of metals under anodic polarization in molten salts is crucial for the development of metallic anodes for molten carbonate electrolysis. Herein, the effects of operating temperature, gas atmosphere, applied current density and electrolysis time on the gas-liquid interfacial corrosion behaviors of nickel anodes in molten Li2CO3-Na2CO3-K2CO3 were systematically investigated. It was found that the gas-liquid interfacial corrosion of nickel anodes was accelerated with decreasing temperature and increasing CO2 content of gas atmosphere. Three distinct corrosion regions of nickel anodes can be identified: (I) the thin salt film region, (II) the meniscus region, and (III) the full immersion region. It was revealed that the formation of negative basicity gradient in the meniscus induced the dissolution/re-precipitation of NiO scale, thereby accelerating the gas-liquid interfacial corrosion of nickel anodes. Furthermore, an Al2O3 sheath was applied to shield the gas-liquid part of nickel electrodes to prevent gas-liquid interfacial corrosion, thus making Ni a stable oxygen-evolution inert anode. [ABSTRACT FROM AUTHOR]

The fascinating search for ultraefficient and high‐powered supercapacitors has stimulated continuous exploration of diverse energy storage materials like transition metal hydroxides with core–shell structure. Thus in this paper, a novel core–shell hybrid electrode material of nickel hydroxide (Ni(OH)2) supported on copper hydroxide nanorod arrays (Cu(OH)2 NAs), which is constructed on copper foam as the substrate by an in situ chemical oxidation reaction accompanied by chemical bath deposition, is reported. As a result, it is found that the pre‐fabricated Cu(OH)2@Ni(OH)2 electrode has a remarkable areal capacitance of 9.27 F cm−2 and good cycling performance (retains 92.38% after 6000 cycles) compared to its counterpart Cu(OH)2 nanorods (88.57%). Additionally, the Cu(OH)2@Ni(OH)2 material, as a positive electrode, can also be used to assemble a hybrid supercapacitor (HSC) while activated carbon is chosen as the negative electrode. As a result, the constructed HSC device with the desired working voltage of 0–1.5 V can light up the light‐emitting diode indicator, proving the potential practicability of the pre‐fabricated HSC device. [ABSTRACT FROM AUTHOR]

Hydrogen energy is a promising energy carrier for powering electric vehicles lying in its dense energy and zero pollution. However, the problems of hydrogen production and control have yet to be resolved. Here we present a novel hydrogen production using zinc plate connected to carbon @ nickel electrode in the alkaline solution, where the device works through zinc oxidation at the anode and hydrogen evolution reaction at the cathode. The results demonstrate that the amount of hydrogen production with carbon @ nickel electrode can be improved 5 times higher than that of nickel electrode, and carbon @ nickel electrode can block zinc oxide adsorption upon nickel surface to keep hydrogen production stable. Moreover, hydrogen production is flexibly controlled by means of switching on/off connection between zinc electrode and carbon @ nickel electrode, facilitating to promote hydrogen application. Lastly, the mechanism of hydrogen evolution reaction is analyzed based on electrochemical characterization and density functional theory calculation, displaying that carbon @ nickel electrode can improve electron transfer ability for hydrogen evolution reaction. • Hydrogen production and control is achieved by Zn and C @ Ni contact. • HER rate is enhanced by carbon in coordination with nickel. • The catalytic and mechanistic properties of C @ Ni electrode is analyzed. [ABSTRACT FROM AUTHOR]

The electrochemical characteristics (activation rate, cyclic stability, and capability to restore the discharge capacity and cyclic stability after a break in cycles) possessed by three samples of the ZrNi1.2Mn0.5Cr0.2V0.1 alloy doped with cathode, rolled cathode, and electrolytic nickel were studied. The impurity content was determined by emission spectral analysis. There were virtually no impurities (except for magnesium and titanium traces) in cathode nickel. In rolled cathode nickel, the largest number of impurities (magnesium and aluminum traces, 0.1 wt.% titanium, 0.1 wt.% copper, 0.1 wt.% silicon, and 0.2 wt.% iron) was revealed. In electrolytic nickel, the largest amount of iron impurities (>1 wt.%) was found. The experiments were performed with electrodes both without and with additions of carbonyl nickel powder (50 and 100% of the electrode weight) used as a catalyst of the electrochemical reaction. The electrodes produced from the alloy samples doped with cathode and rolled cathode nickel showed similar electrochemical behavior, differing significantly from the behavior of the electrodes produced with electrolytic nickel. Thus, the two former electrodes without nickel powder additions activated at 30 °C for three cycles and reached a discharge capacity of 256 and 280 mA∙h/g and that doped with electrolytic nickel activated for six cycles and reached 242 mA∙h/g. Nickel additions amounting to 50 and 100% of the electrode weight to the electrodes produced from samples with cathode and rolled cathode nickel significantly accelerated their activation at 15°C and had almost no effect on the activation at 30°C because it proceeded very quickly at this temperature (for three cycles). An ambiguous effect of catalytic additions in the case of electrodes produced with electrolytic nickel both at 15°C and 30°C (mainly accelerated activation) was revealed. Emission spectral analysis data suggest that this effect is probably due to a relatively large iron amount in the electrolytic nickel, resulting in less stable surface. Depending on the experimental temperature and the presence of activating additions, the discharge capacity of the electrodes produced with cathode and rolled cathode nickel after a breakin the cycles for five days either completely restored or slightly increased. The discharge capacity of the electrodes produced with electrolytic nickel significantly decreased when there was no catalytic addition and practically recovered when it was present. The electrodes produced with cathode and rolled cathode nickel were characterized by a constant rate of loss in the discharge capacity before and after a break in the cycles both at 15°C and 30°C (~0.7 mA∙h/g per cycle), in contrast to the electrodes with electrolytic nickel, whose lost in the discharge capacity was 1.14–1.3 mA∙h/g per cycle and increased to 5.0 mA∙h/g per cycle after a break. The electrode produced with cathode nickel and 50% nickel powder addition, preliminary held in a 30% KOH solution for five days, showed similar discharge capacity and better cyclic stability at 15°C than the electrode at 30°C after a break in the cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • A binder-free, highly-efficient, and nanostructured NiSe 2 electrode was optimized using DOE, by the RSM method, for both electrocatalytic hydrogen and oxygen evolution reaction. • The optimized electrode was synthesized at a frequency of 1200 Hz, a duty cycle of 15%, a current density of 40 mA/cm2, and an electrodeposition time of 7 min. • The optimized electrode was synthesized at a frequency of 1200 Hz, a duty cycle of 15%, a current density of 40 mA/cm2, and an electrodeposition time of 7 min. • The optimized electrode demonstrated better charge transfer resistance, active surface area, and durability stability as cathode and anode for water splitting. In this study, the electrocatalytic activity of Ni-Se electrode synthesized on nickel foam by pulse electrodeposition was optimized through the design of experiments (DOE) approach using the response surface methodology (RSM) for both hydrogen and oxygen evolution reactions. The frequency (f), duty cycle (dc), current density (i), and electrodeposition time (sum of t on s) were chosen as the parameters of the pulse electrodeposition method. The analyses of variance (ANOVA) were performed on the responses of the designed experiments that included the required overpotential at the current density of 10 mA/cm2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) (η 10,HER and η 10,OER), active surface area (R f) and intrinsic electrocatalytic activity (i/R f). The results indicated that η 10,HER , η 10,OER , and R f are mainly influenced by duty cycle and electrodeposition time, while i/R f is affected by frequency and time. The optimized NiSe 2 electrode synthesized under optimal conditions of pulse electrodeposition (low duty cycle and prolonged electrodeposition time) showed the most desirable values for η 10,HER , η 10,OER , and R f , equal to 44 mV (vs. RHE), 235 mV (vs. RHE) and 14700, respectively. The nanostructured NiSe 2 demonstrated the highest potential in the bifunctional application of OER and HER. [ABSTRACT FROM AUTHOR]

Corrosion poses a significant challenge to many materials, from industrial structures to electrochemical catalysts. Nickel (Ni) is considered one of the most active metal catalysts for electrochemical water oxidation reaction in the alkaline environment. To gain more insight into corroded nickel electrodes in the water oxidation reaction, we employed operando ambient pressure x-ray photoelectron spectroscopy to detect the nickel/electrolyte interface under various potentials. To probe the influence of various halide anions on cycled Ni electrode/electrolyte interfaces undergoing the oxygen evolution reaction, we examined the surface changes in nickel electrodes after repeated electrochemical cycles in the presence of KOH mixed with KBr and KI under various potentials. As the applied potential became more anodic, we detected the formation of surface hydroxide and bromide when Br− was present in the electrolyte, whereas in I− -containing electrolytes, we found only hydroxides. The formation of oxidized Ni species was highly dependent on the type and concentration of halide ions. Br− facilitated the formation of more oxidized Ni species than I− did under the same concentration. In the presence of higher concentrations of potassium halide (100 mM) in the bulk electrolyte, metallic nickel could be completely oxidized at the most anodic potentials with surface hydroxide formation. This work reports the observation of cationic metal ions in the bulk electrolyte and describes in situ observation of degradation at the metal/electrolyte interface. [ABSTRACT FROM AUTHOR]

Colloidal nickel nanoparticles were prepared by a top-down approach using an electric discharge. The method was improved by a computerized control unit implemented with virtual instrumentation. A controlled electric arc discharge between two nickel electrodes generates a plasma, which rapidly disintegrates the nickel to form nanoparticles in deionized water. Dynamic light scattering and scanning electron microscopy show synthesis of nickel nanoparticles with size distributions that depend on the discharge parameters. [ABSTRACT FROM AUTHOR]

In this paper, atmospheric reflux in water is used to directly form a nickel sulfide layer in-situ with excellent conductivity sulfide on the surface of spherical nickel hydroxide particles, significantly improving the conductivity of nickel hydroxide particles. The experimental results show that the spherical Ni(OH) 2 @NiS material synthesized by the in situ sulfurization method. As the cathode active material of nickel-iron batteries exhibits excellent electrochemical performance, especially high-rate discharge and cycle performance, which are better than nickel hydroxide electrodes with cobalt oxide. The atmospheric reflux method in water has a simple process and equipment and has no pollution to the environment. Spherical Ni(OH) 2 @NiS materials synthesized by in situ vulcanization can completely replace nickel hydroxide material with cobalt, and they have great commercial application value and market competitiveness as cathode active materials for alkaline nickel-based batteries. [Display omitted] • A NiS layer is formed on the surface of spherical Ni(OH) 2 by in situ vulcanization. • NiS has the same function as γ-CoOOH, and both have good electrical conductivity. • A spherical Ni(OH) 2 electrode with a NiS layer shows excellent electrochemical performance. • In situ NiS instead of cobalt additives can significantly reduce the cost of nickel electrodes. [ABSTRACT FROM AUTHOR]

Nickel-based thin film electrodes were electrodeposited onto copper substrate using a deep eutectic solvent. The supercapacitor performance of these electrodes in alkaline KOH solution was greatly enhanced by altering surface roughness of coatings. In order to create a rougher surface, two paths were followed. In the first path, Ni-only coatings were prepared at different deposition potentials and smooth-to-rough transition in surface morphology took place at higher potentials due to increasing emission of hydrogen bubbles. In the second path, Ni–Zn binary coatings with varying zinc concentration were electrodeposited and surface roughness was formed by dealloying zinc element from the electrodes as corroborated by Scanning Electron Microscopy and Atomic Force Microscopy results. In both paths, noticeable improvements in the capacitance of nickel electrodes were observed upon the apperance of rougher surface. A linear relationship was discovered between cathodic peak currents and polarization values in the cyclic voltammetry scans of electrodes, possibly for the first time here in literature. The increase in polarization was explained by the decrease in electrode conductivity proved by dwindling of metallic nickel peaks in X-ray diffraction upon electrochemical testing. [ABSTRACT FROM AUTHOR]

Nickel foam is widely used as a current lead/current collector and the basis of nickel hydroxide electrodes for various electrochemical devices – batteries, hybrid supercapacitors, devices for electrocatalytic oxidation of organic substances. The characteristics of commercial samples of nickel foam produced by Novomet-Perm (Russian Federation) obtained by electroless and then electrochemical nickel plating and Linyi Gelon LIB Co Ltd (China) obtained by electroless nickel plating were studied. The nature of passivity was determined by forming model samples of electrochemical and electroless nickel on a steel base. For the passive sample, activation was carried out by applying a layer of electrochemical nickel from an impact nickel plating solution. Activated, non-activated samples of nickel foam, as well as model samples, were studied by the methods of cyclic voltammetry and galvanostatic charge-discharge cycling in the supercapacitor mode. Comparative analysis of Chinesemade and Russian-made nickel foam samples showed significant passivity of the former – in cyclic voltammetry, the activity was 4.8 times lower, with galvanostatic charge-discharge cycling – 2.59 times lower. It was suggested that high passivity was determined by the fact that the sample consisted of Ni-P or Ni-B alloy. This assumption was proved by the method of natural simulation. The electrochemical activity of electroless nickel was 1.25 times lower than that of electrochemical nickel (according to cyclic voltammetry data) and 1.58 times lower (according to galvanostatic cycling data). For the first time, Chinese-made nickel foam (electroless nickel) was activated by applying a layer of electrochemical nickel from an impact nickel electrolyte. The high activation efficiency was shown as follows – on the cyclic curve, the specific current of the anodic peak increased 8.71 times, and with galvanostatic cycling, the increase in specific capacity was from 1.73 times (at i=120 mA/ cm²) to 4.84 times (at i=20 mA/cm²). [ABSTRACT FROM AUTHOR]

Nickel boride has attracted great interest in the field of energy storage due to its superior electrochemical performance, However, particles agglomeration and poor electability have limited its wider application. Clay minerals with high specific surface area and excellent wettability can reduce the agglomeration of particles. We synthesized eight kinds of composites Ni 3 B@montmorillonite (Ni 3 B@Mt), Ni 3 B@chlorite (Ni 3 B@Chl), Ni 3 B@vermiculite (Ni 3 B@Ver), Ni 3 B@kaolinite (Ni 3 B@Kaol), Ni 3 B@palygorskite (Ni 3 B@Pal), Ni 3 B@halloysite (Ni 3 B@Hal), Ni 3 B@sepiolite (Ni 3 B@Sep), and Ni 3 B@talc (Ni 3 B@Tal) materials with different morphologies and structures by simple liquid phase reduction method. We explored the influence of a series of clay minerals on the electrochemical performance of Ni 3 B. The results show that the specific capacitance of the Ni 3 B@clay minerals composites has been improved in different degrees. In addition, the Ni 3 B@Mt. shows the best specific capacitance of 1406 F g−1 at a current density of 0.5 A g−1, and still maintains a high specific capacitance of 944 F g−1 at a current density of 5 A g−1. The assembled asymmetric supercapacitor Ni 3 B@Mt.//AC using an activated carbon (AC) and the Ni 3 B@Mt. showed excellent electrochemical performance with achieving the maximum energy density of 92.60 W h kg−1 at the power density of 350 W kg−1, which suggests the practical application of clay minerals in the electrochemical energy storage field. • A series of clay modified nickel boride composites have been prepared. • The effects of clays with different structure on the electrochemical properties of nickel boride were explored. • The montmorillonite modified nickel boride electrode possessed an excellent electrochemical performance. • The assembled asymmetric supercapacitor had superior energy density. [ABSTRACT FROM AUTHOR]

Carbene-ligated nickel(II) complexes self-assemble into exceptionally robust and efficient homogeneous water oxidation catalysts. The resulting stable thin film bonds metal electrode through poly-imidazole bridges, making them supported heterogeneous electrochemical catalysts that are resilient to leaching and stripping. The electrochemical OER with our nickel-carbene catalysts exhibits excellent current densities with high efficiency, low Tafel slope, and useful longevity for a base metal catalyst. [Display omitted] The oxygen evolution reaction (OER) of water splitting is essential to electrochemical energy storage applications. While nickel electrodes are widely available heterogeneous OER catalysts, homogeneous nickel catalysts for OER are underexplored. Here we report two carbene-ligated nickel(II) complexes that are exceptionally robust and efficient homogeneous water oxidation catalysts. Remarkably, these novel nickel complexes can assemble a stable thin film onto a metal electrode through poly-imidazole bridges, making them supported heterogeneous electrochemical catalysts that are resilient to leaching and stripping. Unlike molecular catalysts and nanoparticle catalysts, such electrode-supported metal-complex catalysts for OER are rare and have the potential to inspire new designs. The electrochemical OER with our nickel-carbene catalysts exhibits excellent current densities with high efficiency, low Tafel slope, and useful longevity for a base metal catalyst. Our data show that imidazole carbene ligands stay bonded to the nickel(II) centers throughout the catalysis, which allows the facile oxygen evolution. [ABSTRACT FROM AUTHOR]

• UEO on nickel(III) is studied with real human urine. • Strong competitive effects are highlighted by spiking urine-contained organic compounds. • Kinetic partial order of urea falls down to a very low value in urine medium. • UEO on nickel electrode is implemented for the first time at pilot-scale. • Urea-to-hydrogen valorization is demonstrated at pilot-scale with real human urine. This paper presents an investigation into urea-to-hydrogen valorization through electro-oxidation on nickel(III). The study has dual objectives: (i) to gain a better understanding of the effects of organic compounds (other than urea) in human urine on UEO and (ii) to upscale the process to pilot-scale. Initial voltammetric studies at lab-scale using real human urine showed that urea adsorption on nickel(III) sites, followed by its electro-oxidation, competes with molecules such as creatinine, histidine, and creatine. Notably, creatinine reduced the nickel(II) oxidation signal by up to 20 %, indicating its reaction precedence over urea. Additionally, the oxidation rate of urea by nickel(III) in urine exhibited a much lower partial order (0.1), as opposed to 0.3 in KOH solution, confirming the impact of competitive adsorption. Subsequently, UEO experiments were upscaled using a specially designed 1 L undivided tubular EC reactor operating in multi-pass mode. Potentiostatic electrolysis of a urea synthetic solution was conducted over 70 h, achieving nitrogen and carbon species mass balances of over 97 %—a milestone previously unreported at this scale. The study further examined the influence of operating parameters such as anode surface area, flow rate and applied potential on the EC process. This investigation underscored the impact of factor like reactor geometry, controlled potential and temperature on process efficiency. Parameters for optimal N 2 production, highest urea conversion rate, etc., were also defined. Finally, the electrolysis of human urine at pilot-scale unveiled new challenges distinct from those encountered with urea synthetic solutions. [ABSTRACT FROM AUTHOR]

Battery‐type electrode materials such as NiS applied in Faradaic supercapacitors (FSs) could display poor performance with regard to rate‐capability and cycling stability due to the inappropriate texture of the electrodes. Numerous works focussed on tuning the microscopic structure of electrode materials, but neglected the influence of the microscopic structure of current collectors such as nickel foam on the electrochemical performance of FSs. In this work, the performance of NiS is associated with the microscopic structure of nickel foams by decorating the 2D porous nanostructured NiS on a 2D nanoengineered skeleton‐surface of nickel foams. It could be inferred from the characterization results that the synergistic effect of both 2D nanostructured NiS and nickel foam significantly promotes the rate‐capability and stabilizes the performance of NiS. Asymmetric supercapacitors using the dually nanostructured NiS/nickel foam as positive electrode and AC as negative electrode exhibit both high energy and high power densities. [ABSTRACT FROM AUTHOR]

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Single‐atom catalysts (SACs) show great promise for electrochemical CO2 reduction reaction (CRR), but the low density of active sites and the poor electrical conduction and mass transport of the single‐atom electrode greatly limit their performance. Herein, we prepared a nickel single‐atom electrode consisting of isolated, high‐density and low‐valent nickel(I) sites anchored on a self‐standing N‐doped carbon nanotube array with nickel–copper alloy encapsulation on a carbon‐fiber paper. The combination of single‐atom nickel(I) sites and self‐standing array structure gives rise to an excellent electrocatalytic CO2 reduction performance. The introduction of copper tunes the d‐band electron configuration and enhances the adsorption of hydrogen, which impedes the hydrogen evolution reaction. The single‐nickel‐atom electrode exhibits a specific current density of −32.87 mA cm−2 and turnover frequency of 1962 h−1 at a mild overpotential of 620 mV for CO formation with 97 % Faradic efficiency. [ABSTRACT FROM AUTHOR]

Nickel oxide, as a typical pseudocapacitive material, holds great promise for boosting the energy storage capability of supercapacitors (SCs) owing to its great advantages, such as high theoretical capacitance value, low‐cost, good stability, and environmentally benign nature. Nevertheless, many obstacles, including low intrinsic conductivity and limited surfice electrochemically active sites, need to be overcome before its practical implementation. In this review, the recent advances on nickel oxide‐based electrode materials are outlined with particular attention paid to strategies for enhancing their SC performance. To begin, an introduction to the physical and chemical properties of nickel oxide and its charge storage mechanisms is presented, followed by a discussion of the obstacles to its widespread implementation and the corresponding strategies for constructing high‐performance nickel oxide‐based electrode materials. After that, recent progress in the use of organic electrolyte systems to achieve improvements in integrated device performance is highlighted. To conclude, a detailed discussion on future trends and opportunities associated with NiO‐based electrode materials for future SCs is provided. [ABSTRACT FROM AUTHOR]

The corrosion inhibition of nickel in 0.5 M H2SO4 by cysteine was investigated with various electrochemical methods and surface observations by SEM. The cyclic voltammetry revealed that the current density is the highest in absence of the cysteine and decreases with increasing inhibitor concentration. The cysteine is an anodic inhibitor. The polarization and electrochemical impedance spectroscopy showed that the cysteine has a poor inhibitive effect. The surface observation by scanning electron microscope corroborates the addition of cysteine has no significant improvement of the surface morphology of nickel electrode in 0.5 M H2SO4. Results obtained by different methods corroborate each other. [ABSTRACT FROM AUTHOR]

[Display omitted] • A more compact PbO 2 electrode was prepared by co-doping with Ni and SDS. • Higher O ad content was observed for Ni-SDS-PbO 2. • The production of •OH was significantly improved. • The electrocatalytic activity for tetracycline degradation was greatly enhanced. A PbO 2 electrode co-doped with nickel (Ni) and sodium dodecyl sulfate (SDS) was prepared with TiO 2 nanotube as the substrate by a simple electro-deposition method. The morphology, composition and structural information were characterized by SEM, XPS and XRD. The techniques of linear sweep voltammetry and electrochemical impedance spectroscopy were used to investigate electrochemical properties. The characterizations indicated that an increased OEP value and a higher O ads content were obtained for Ni-SDS-PbO 2. The experimental results confirmed that the yield rate of ·OH by Ni-SDS-PbO 2 was 2.21 times as high as that by the undoped PbO 2. Accordingly, the electrocatalytic degradation of tetracycline by Ni-SDS-PbO 2 was the fastest. The corresponding pseudo-first-order kinetic constant for Ni-SDS-PbO 2 was the highest (0.0504 min−1), and it was 2.83 times as high as that for the pristine PbO 2. The increased electrocatalytic performance of Ni-SDS-PbO 2 and its enhanced stability could be attributed to the co-modification of Ni and SDS. [ABSTRACT FROM AUTHOR]

The present investigation deals with the development, characterization and application of nanostructured Pd doped Ni electrodes (Pd@Ni), which uses the electrochemical properties of Pd in synergy with the magnetic properties of Ni for biosensors development. The Pd@Ni electrodes have been characterized by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. It has been shown that palladium presented spherical assemblies ranging 150–200 nm medium diameter size that covers large areas of the electrode surface while metallic nickel, which confers magnetic properties, showed a uniform granular structure with sizes between 20 and 50 nm. Cyclic voltammetry and electrochemical impedance spectroscopy were performed to understand the electrochemical process at the Pd@Ni electrodes in neutral media. The Pd@Ni electrodes were applied for the electrochemical detection of H 2 O 2. Finally, Ni nanoparticles (NiNP) functionalized with the model enzyme glucose oxidase (GOx-NiNP) have been attached to the Pd@Ni electrode solely through magnetic interactions, and the obtained GOx-NiNP/Pd@Ni biosensor applied for glucose determination in aqueous solutions by fixed potential amperometry at −0.05 V (vs Ag/AgCl) with reduced interferences. Image 10197 • Palladium doped nickel electrodes and nickel nanoparticles. • Benefits from the catalytic effect of Pd and the magnetic properties of Ni. • Oxidase immobilization solely through magnetic interactions. • Palladium doped nickel electrodes for the detection of H 2 O 2. • Biosensor operates at low potential values avoiding interfering compounds. [ABSTRACT FROM AUTHOR]

Abstract This work reports the development of a dimethylglyoxime (DMG) modified sensor in which the complexing agent was successfully immobilized by drop-casting onto a screen-printed carbon electrode support (SPCE). The experimental conditions for the preparation of the DMG-SPCE sensor were optimized by means of a D-optimal design, and the built sensors were analytically evaluated for the determination of Ni(II) by adsorptive stripping voltammetry (AdSV). Its analytical performance suggests its suitability for the determination of Ni(II)-ions by AdSV at concentration levels of μg L−1 (LOD of 2.3 μg L−1, linear range from 7.6 to 200 μg L−1). Finally, the applicability of the developed sensor was assessed by the determination of trace levels of Ni(II) by AdSV in a wastewater reference material with a very high reproducibility (0.005%) and good trueness (0.1%). Graphical abstract Unlabelled Image Highlights • Reagent-less dimethylglyoxime based screen-printed electrode for Ni(II) determination • Optimization of the experimental conditions through a D-optimal design • Limit of detection down to 2.3 μg L−1 and wide linear range (7.6–200.0 μg L−1) • Good trueness in the analysis of a certified wastewater reference material [ABSTRACT FROM AUTHOR]

[Display omitted] • Co 3 S 4 /Ni 3 S 4. nanowires grown on nickel foam are obtained by a two-step hydrothermal method. • The Co 3 S 4 /Ni 3 S 4 cathode exhibits an excellent electrocatalytic dechlorination performance of Florfenicol. • High electron transfer performance is achieved by unique morphology and heterogeneous structure. • Innovative application of non-noble metals in electrocatalytic dechlorination. Chlorinated antibiotics, particularly Florfenicol (FF), pose a serious global threat to humans and animals by contaminating freshwater and causing water pollution. Electrocatalytic dechlorination (ECH) is effective for removing chlorinated organic compounds during wastewater treatment and water remediation, however, there are limited reports on high-performance, cost-effective, and environmentally friendly cathode materials. In this study, a catalyst was prepared using a two-step hydrothermal process, and a vertically grown 2D Co 3 S 4 /Ni 3 S 4 heterostructure was constructed on a nickel foam electrode. Owing to its inherently high electron transfer performance and H* adsorption properties, extensive dechlorination of FF could be achieved via cathodic reduction. The electrode formed using a 100 mM Na 2 S concentration during the hydrothermal reaction exhibited an optimal crystal composition and morphology, resulting in a substantial electrocatalytic dechlorination effect exhibiting nearly 100 % FF removal after 120 min at −1 V vs Ag/AgCl. The experimental results indicated that the dechlorination of FF is primarily achieved via direct electron transfer, with the degradation rate decreasing by only 5 % after the addition of 400 mM tert -butanol, confirming that H* played a supporting role. Therefore, this study proposes a cost-effective and sustainable electrochemical approach for reducing chlorinated antibiotics using a highly efficient non-noble metal electrode material. It can be successfully utilized as an effective, eco-friendly electrochemical strategy for the removal of similar antibiotics. [ABSTRACT FROM AUTHOR]

This is an overview of the electrochemical characterization of nickel and stainless steel (so‐called SS) as electrodes in medical devices for the early diagnosis of small fiber neuropathy that originates from type‐2 diabetes or cystic fibrosis. The electrical current responses obtained during the clinical tests are related to the amount of chloride present on the sweat. SS electrodes are now used to replace nickel because this later not only presents problems with chloride sensitivity but its contact with skin can cause possible allergic reactions for some patients. For the above reasons, several types of SS were studied. It was shown that some of them perform well and have lower costs than Ni electrodes. We discuss the state of the art of the electrochemical studies conducted with nickel and steels under physiological or biomimetic conditions and discuss the advantages of a particular steel over the others depending on the conditions, especially chloride concentration. [ABSTRACT FROM AUTHOR]

The behavior of complexes of iron, nickel, zirconium and copper as an electrode in alkaline, acidic and neutral solution has been investigated primarily by cyclic voltammetry. Cyclic voltammetry is a classical measuring method in electro-analytic chemistry which is used for the study of catalysis and charge transfer. For the complexes [Fe-Cu], [Ni-Ni], [Zr-Zr] and [Cu-Cu] as well as for supported catalysts, it was possible to determine various oxidation reactions with the cyclic voltammetry method. For this method, these complexes and catalysts were coated on nickel electrodes and using cyclic voltammetry following reactions were carried out (a) oxidation of CH3OH, (b) oxidation of NaCl and (c) oxidation of NaOH. The cyclic voltammogram presented in this work were shown to have different oxidation states and reduction states depending upon the kind of chemical reaction carried out, nature of complex utilized, the nature of support as well as how the complex is bonded to the support. [ABSTRACT FROM AUTHOR]

Abstract: The design and synthesis of Pt‐based electrocatalysts for the hydrogen evolution reaction (HER) are of great importance for the successful development of hydrogen‐based alternative energy technologies. Although Pt is considered to be the most active catalyst for the HER, its reaction performance is limited in alkaline solutions owing to a slow rate for water dissociation. Therefore, many research groups have intensively investigated reaction mechanisms and developed system designs and efficient Pt‐based catalysts to enhance the alkaline HER. Herein, we summarize the catalytic surface specificity of Pt and Pt–Ni(OH)2 materials to control the kinetics of the alkaline HER. In particular, we increase our understanding of Ni(OH)2‐modified Pt surfaces and the corresponding nanoscaled Pt–Ni(OH)2 electrocatalysts to improve the sluggish water‐dissociation step, and this knowledge will guide us to future sustainable energy applications of advanced nanomaterials. [ABSTRACT FROM AUTHOR]

Three nickel electrodeposits with comparable grain size were synthesized by tailoring the electrodeposition conditions. Thorough microstructural characterizations including electron backscatter diffraction, ion channeling contrast imaging, electron channeling contrast imaging, transmission Kikuchi diffraction, transmission electron and high annular dark-field imaging were applied. The deposits contain a high density of twin boundaries with similar microstructures in terms of grain boundary character. These materials were annealed at various temperatures to study the microstructural evolution, and hence, their thermal stability. The differences in the character of twin boundaries and morphology of the grain boundaries in as-deposited state and their influence on the microstructural evolution at elevated temperatures are analyzed. The importance of incoherent twin boundaries, and the interaction of mobile general high angle boundaries with stationary boundaries are discussed. Finally, an optimal design for high thermal stability is proposed, based on the mechanisms that were inferred from the results. [ABSTRACT FROM AUTHOR]

The influence of the temperature on the kinetics of the hydrogen oxidation (HOR) and evolution reactions (HER) on Ni electrodes has been explored in the range from 298 to 338 K. By combining an expexrimental cyclic voltammetry study and microkinetic modeling, the rate constants and the activation energies of the individual Volmer-Tafel-Heyrovsky steps have been extracted for two surface states of Ni electrode, namely metallic Ni and partially oxidized one. The kinetic model suggests that the HOR/HER on metallic Ni follows the Heyrovsky-Volmer mechanism characterized by strong adsorption of the hydrogen intermediate and low reaction rate. Partial coverage of the electrode surface with Ni oxide species results in a decrease of the strength of adsorption of hydrogen atoms and an increase of the rate of the Volmer step thus leading to a significant enhancement of the HOR/HER kinetics. Furthermore, the kinetic model provides evidence for a contribution of the Tafel step in the reaction mechanism for a partially oxidized electrode. The apparent activation energy is shown to be slightly dependent on the surface state, decreasing from 30 ± 1 for metallic to 26 ± 1 kJ mol −1 for partially oxidized Ni. [ABSTRACT FROM AUTHOR]

A low-cost, facile and highly efficient in situ solvothermal reaction has been developed for the first time to synthesize, by using a 3D Ni foam template, three-dimensional nickel-antimony (3D NiSb) thin films as anode electrode materials for use in sodium-ion batteries (SIBs). The structure design and preparation have proved reasonable and efficient, leading to excellent electrochemical properties. At current densities of 100, 200 and 400 mA g-1, specific capacities of 643.8, 520.5 and 378.6 mA h g-1, respectively, could be obtained. Additionally, a specific capacity of 420 mA h g-1 could be achieved after 100 cycles at a current density of 100 mA g-1. This could be attributed to the special 3D binder-free conductive network connecting the NiSb nanoparticles and the 3D contact area with the electrolyte, which is beneficial for the charge-transfer kinetics and electrochemical performance. Moreover, the porous structure offers enough space to alleviate the volume changes and stress generated in the sodiation/desodiation process. Most importantly, the 3D porous Ni foam, as a support for NiSb nanoparticles, can effectively prevent the agglomeration of the NiSb and Na3Sb nanoparticles. Therefore, such a unique NiSb anode material may be of great significance in next-generation energy storage devices. [ABSTRACT FROM AUTHOR]