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Metal–organic frameworks, as a kind of advanced nanoporous materials with metal centers and organic linkers, have been applied as promising electrode materials in energy storage devices. In this study, we are successfully prepared cobalt sulfide nanosheets (CoS) derived from the metal–organic framework on nickel foam (NF). The prepared electrodes are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller and Barrett-Joyner-Halenda and electrochemical methods like voltammetry, galvanostatic charge–discharge curve and electrochemical impedance spectroscopy. The CoS/NF electrode demonstrates a high specific capacity of 377.5 mA h g−1 (1359 C g−1) at the current density of 2 A g−1, considerable rate performance and excellent durability (89.4% after 4000 cycles). A hybrid supercapacitor is assembled using CoS/NF as the positive electrode and activated carbon as the negative electrode, it shows a high energy density of 57.4 W h kg−1 at a power density of 405.2 W kg−1. The electrochemical results suggest that the CoS nanosheet arrays would possess excellent potential for applications in energy storage devices. [ABSTRACT FROM AUTHOR]

In this research, a thin layer of multi-metallic non-precious catalyst is prepared by electroplating from an electrolyte bath containing Ni, Co, and Fe sulfates over pressed commercial nickel foam electrode. The composition of the deposited catalytic film and its morphology are characterized by scanning electron microscopy (SEM) with energy dispersion X-ray (EDX) techniques. The efficiency of the prepared binder-free electrodes for electrochemical water splitting is investigated in a self-designed short water electrolysis stack with zero-gap configuration of the integrated single cells and hybrid electrical connections. The separator used is a commercial Zirfon Perl 500 membrane, doped with 25% KOH. The performance of the catalyst, the single cells, and the developed electrolyzer stack are examined by steady state polarization curves and stationery galvanostatic stability tests in the temperature range 20 °C to 80 °C. The NiFeCoP multi-metallic alloy demonstrates superior catalytic efficiency compared to the pure nickel foam electrodes and reliable stability with time. The single cells in the stack show identical performance and the cumulative stack parameters strictly follow the theoretical considerations. The applied hybrid electrical connections enable scaling of both the stack voltage and the passing current, which in turn ensures flexibility with regard to the input power and the hydrogen production capacity. [ABSTRACT FROM AUTHOR]

BACKGROUND: Nickel foam (NF) is widely used as battery electrode matrix and electrochemical process cathode. However, the surface of NF is prone to oxidation, which may affect its ability to reduce oxygen and produce H2O2, but the influence mechanism is still unclear. In this paper, surface oxidation of the NF was regulated by pickling and drying pretreatment, and the surface oxides were characterized by X‐ray photoelectron spectroscopy (XPS) and energy dispersive X‐ray spectrometry (EDS). The NF was used as the substrate, graphite powder as the catalyst, and PTFE as the binder to prepare graphite‐coated NF composite electrodes. The effect of NF surface oxidation on their ability to generate H2O2 was investigated. RESULTS: The results demonstrated that after pickling and drying, the NF surface generated a large amount of NiO, which increased the charge transfer resistance of the NF by 20.3%, and accelerated further reduction decomposition of H2O2. The rotating ring‐disk electrode (RRDE) tests further confirmed that NiO can reduce the two‐electron oxygen reaction selectivity, which was detrimental to H2O2 electrosynthesis. The graphite‐coated NF composite electrode with pristine NF as the substrate can produce 869.1 mg L−1 of H2O2 and maintain relatively good reusability. CONCLUSION: Overall, the surface oxidation of NF is not conducive to H2O2 electrosynthesis, and it is necessary to prevent oxidation during electrode preparation. This study provides a valuable reference for the preparation of NF electrodes and can promote the further study of in situ H2O2 electrosynthesis. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

To achieve carbon neutrality, the development of effective and durable electrodes for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of utmost importance. Herein, the Ru 3.4 -PMOF/NF electrode was successfully prepared by immobilizing Ru nanoparticles on porphyrinic metal-organic framework/nickel foam (PMOF/NF), effectively driving both the OER and the HER in an alkaline electrolyte. To achieve 10 mA cm−2, the Ru 3.4 -PMOF/NF electrode only required overpotentials of 19 and 215 mV for HER and OER, respectively. For overall water splitting, an ultra-low cell voltage of 1.468 V was required to drive 10 mA cm−2, surpassing the performance of the integrated Pt/C and RuO 2 couple electrode (1.6627 V). The outperformed electrocatalytic activity could be ascribed to the well-dispersed Ru nanoparticles, the self-reconstruction of PMOF, the synergistic effect, and the lamellar morphology. This study offers a promising approach for the development of ruthenium-doped electrodes that can enhance the efficiency of electrocatalytic water splitting. • The self-supporting electrode was prepared by immobilizing Ru on PMOF/NF. • The Ru 3.4 -PMOF/NF exhibited better HER and OER performance than Pt/C and RuO 2. • The Ru 3.4 -PMOF/NF couple could achieve a low cell voltage for water splitting. • The reasons for the improvement of electrocatalytic performance were summarized. [ABSTRACT FROM AUTHOR]

In this work, ultrathin nickel films are developed for application as transparent electrodes in thermoelectric devices. The quality of the films is determined systematically by electrical, optical, and morphological characterization in a series of samples with different thickness. The thermal properties of the films show a dramatic dependence of the Seebeck coefficient on the film thickness. This dependence, with values ranging from −16 to +5 휇V K−1 for thicknesses from 10 to 2 nm, includes a change in the behavior of the thermoelectric response from n‐ to p‐type. It has also been demonstrated that the accurate estimation of the thermal conductivity in thin films is challenging due to substrate effects. In this situation, a differential measurement method based on scanning thermal microscopy is proposed, as in these conditions the measurements are less sensitive to the substrate effects. In further works, the dependence of the thermal properties of ultrathin nickel films can be exploited as a tuning parameter for the design of thermoelectric devices. [ABSTRACT FROM AUTHOR]

Direct methanol fuel cell is an emerging energy transformation system with the prospect of substituting secondary batteries soon due to their exciting features. One of the most limitations is the weak catalytic activity of the expensive nonprecious Pt-based catalysts at the fuel cell's anode. In this work, a standalone Nickel layered double hydroxide of hierarchical nanosheet structure was effectively synthesized on the nickel foam's surface through facile hydrothermal treatment that subsequently converted into NiO without destroying the structure by heat treatment at 500 °C. The synthesized standalone electrodes demonstrated a significant activity for methanol oxidation with an onset potential of 0.35 V in KOH (1 M), which is attributed to the Ni(OH) 2 (Ni+2)/(Ni+3) NiOOH active site. The electrodes effectively discharged current at 0.5 V for more than 1 h with no performance degradation compared to the bare nickel foam. The better activity of the synthesized electrodes was attributed to the nanosheet structure layer's better charge and mass transfers, as confirmed by the morphological images (SEM images) and the electrochemical characteristics (electrochemical impedance spectroscopy, chronoamperometry, and cyclic voltammetry). [Display omitted] • Standalone Nickel layered double hydroxide (Ni-LDH) nanosheet structure was prepared. • Nickel oxide (NiO) was prepared by heat treatment of Ni-LDH at 500 °C. • The synthesized electrodes demonstrated a significant activity for methanol oxidation. • Nanosheet structure exhibited better charge and mass transfers, and thus activity. • The electrodes have high stability during long-term oxidation activity. [ABSTRACT FROM AUTHOR]

A new approach for the determination of atenolol (ATN) at a graphite polyurethane composite electrode (GPUE) modified with electrodeposited nickel(II) nanoparticles electrochemically pretreated in alkaline medium (GPUE-NiNP) is reported. The electrodeposition of NiNP on the GPUE surface was performed by 5 scans in cyclic voltammetry between 0.0 to −1.5 V (vs. SCE) and scan rate of 20 mV s−1 in a 0.05 mol L−1 NiSO4 and 0.32 mol L−1 H3BO3 solution at pH 5. After deposition, the GPUE-NiNP was submitted to an electrochemical pretreatment in 0.50 mol L−1 NaOH by cyclic voltammetry at 100 mV s−1. The best results were obtained after 50 cycles at 100 mV s−1. Quantitative measurements at GPUE-NiNP were performed using differential pulse voltammetry (DPV) in pH 11 universal buffer. Atenolol promotes a decrease in the nickel oxide signals probably due to a complexation of the analyte with free Ni2+ in solution. Thus, the analyte was quantified by the signal suppression and an analytical curve was obtained at the GPUE-NiNP using the optimized conditions for 1.0 to 100 x 10−8 mol L−1 atenolol between 1.0 and 0.0 V (vs. SCE) with a linear range between 2.0 x 10−8 and 1.0 x 10−7 mol L−1 and a limit of detection of 3.47 x 10−9 mol L−1 with R = 0.9995 for GPUE-NiNP. The procedure was applied to three commercial pharmaceutical formulations with recoveries between 99.5 and 100.7% and agreed with a comparative HPLC procedure within 95% confidence level according to the Student's t-test. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting using renewable energy is considered a key technology to mitigate global warming and to realize the hydrogen economy. Extensive efforts have been devoted to finding high-performance electrode catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) involved in electrochemical water splitting, whereas the research on added components in the electrolyte to boost HER and/or OER is very limited. In this work, we report the use of 18-crown ether-6 (18C6) in the electrolyte as a bifunctional booster in water splitting. The addition of 18C6 in alkaline electrolyte drastically boosts HER current density from −50 to −300 mA cm−2 at −0.3 V vs. RHE and OER current density from 25 to 250 mA cm−2 at 1.7 V vs. RHE on the Ni foam electrode. Combing DFT calculations and experimental characterizations, the functions of 18C6 in boosting HER and OER on nickel electrodes under the alkaline condition are revealed. This research demonstrates the potential of macrocycle molecules as electrolyte additives and opens up new opportunities for boosting the performance of water splitting. The macrocycle molecule crown ether as an additive in the alkaline electrolyte boosts electrochemical water splitting by accelerating the kinetics of both HER and OER. [Display omitted] • Crown ether 18C6 in alkaline electrolyte boosts water splitting on Ni electrode. • HER current increases from −50 to −300 mA cm−2 at −0.3 V vs RHE. • OER current increases from 25 to 250 mA cm−2 at 1.7 V vs RHE. • Characterizations and DFT calculations are conducted to reveal the mechanisms. [ABSTRACT FROM AUTHOR]

The widespread use of unsustainable fossil fuels has caused serious damage to the ecological environment. The development of sustainable clean energy is urgent. Producing hydrogen by water electrolysis can effectively solve fossil energy shortage and environmental pollution issues. The preparation of inexpensive, efficient, and stable electrocatalytic hydrogen evolution electrode materials is the key to achieving the application of electrocatalytic hydrogen evolution. Herein, the amorphous nickel oxide/nickel foam (NiO x /NF) hydrogen evolution electrode was prepared by a simple one-step hydrothermal method with hydrogen peroxide as an oxidant. The amorphous leaf array structure of NiO x /NF electrode can enrich the surface composition and expose more catalytic active sites. Further, hydrogen peroxide etching can optimize the electronic structure of NiO x , and accelerate the electron migration. Thus, NiO x /NF displays excellent alkaline hydrogen evolution activity with the low over potentials of 70, 318 and 361 mV at 10, 500 and 1000 mA cm−2, respectively, leading to high performance in alkaline HER than those of reported Ni-based electrodes and even surpasses commercial Pt/C at high current density. Our work provides a new approach for developing inexpensive electrocatalysts with excellent alkaline hydrogen evolution activity and stability. [Display omitted] • Amorphous NiO X /NF electrocatalyst was developed in a simple hydrothermal process with hydrogen peroxide as an etchant. • Hydrogen peroxide etching optimized the electronic structure of NiO X , and increased the electron transfer rates. • NiO X /NF exhibited admirable alkaline HER activity (η 10 of 70 mV, 68.2 mV dec-1) and excellent long-term stability. • NiO X /NF displayed obvious advantages at a practical current density of 500 mA cm-2 over commercial Pt/C. [ABSTRACT FROM AUTHOR]

A two-step electrolytic deposition of Ni and Pt from aqueous solutions formed a porous Ni–Pt alloy surface. A nickel sample with a thin layer of platinum covered by a nickel electrode coating was used in the electrolysis of aluminium from molten salts at 900°. The molten salt was a mixture of 48.25 mol% NaCl, 48.25 mol% KCl and 3.5 mol% AlF 3. Deposition of Al on Ni and Pt samples was carried out at a potential of −1.8 V, respectively. Al and the resulting intermetallic phases were dissolved at −0.5 V to produce porous Ni–Pt alloy foams. It was found that a porous Ni–Pt alloy layer is formed due to an intense reaction between liquid Al and solid Ni, which propagates deep into the solid material. The high temperature of the molten salts allows the metallic Pt to penetrate deep into the porous structure. It makes it possible to obtain a uniform Pt distribution in the electrode volume. The fabricated porous Ni–Pt alloy was tested in cathodic and anodic polarisation measurements in an aqueous solution of 10 wt% KOH to assess their electrocatalytic activity. During constant-voltage electrolysis, a solid-electrolyte hydrogen sensor was coupled to the experimental system and allowed the in-situ hydrogen production efficiency to be measured. The promising electrochemical performance of porous Ni–Pt alloys as electrode materials for hydrogen and oxygen release in alkaline solutions was confirmed by measuring the partial pressure of hydrogen in electrolysis at constant voltage. Due to the large amount of highly active surface area, the porous Ni–Pt alloys showed a significantly higher current density than untreated samples in hydrogen evolution reactions. Based on cyclic voltammetry measurements, it was demonstrated that the electrochemically active surface area was highest for the modified Ni–Pt electrode. The Pt-modified sample with Al deposition at −1.8 V and a molten salt temperature of 900 °C generated the highest amount of hydrogen (9.38 mL). • Porous Ni–Pt alloy was formed by Al-Deposition/Dissolution molten salt electrolysis. • The hydrogen evolution intensity was in-situ measured by the hydrogen sensor. • Application of temperature 900 °C allow to obtain even distribution of Pt in porous body. • Porous Ni–Pt electrodes are highly-active in HER/OER in alkaline solutions. [ABSTRACT FROM AUTHOR]

The present paper deals with hydrogen generation using sono-electrolysis. The experimental investigation is based on a parametric study of water electrolysis system according to the nature of the dissolved salt KOH/NaOH, the concentration of salt in the electrolyte, the temperatures of the electrolyte and the bath (27, 40, 45, 50, 55 and 60 °C), and the nature of the electrode (stainless steel 304, nickel, nickel foam and graphite). Two electrolyzer designs were adopted, namely Hoffmann cell and H-cell. The parametric study revealed the optimum configuration under silent conditions, before integrating the ultrasound power both in continuous and pulsed modes, in order to assess its effect on the energy efficiency of the process and the kinetics of hydrogen production. Under optimal conditions of electrolyte and electrode material, i.e., in KOH electrolyte using nickel foam electrodes, the integration of continuous ultrasound resulted in an increase of 7.78% in the cell current under ambient temperature, corresponding to 64% reduction in the bubble resistance. With the same configuration, the effect of sonication was negligible at the optimal solution temperature of 45 °C, while room temperature operation of the sono-electrolyzer conducted to a better performance than under silent conditions. Finally, continuous sonication mode led to the most performant operation with all the studied configurations, both kinetically and energetically, as compared to pulsed mode. • The geometry of the electrolytic cell controls the ionic transport between both anodic and cathodic compartments. • The effect of the electrolyte in sono-electrolysis is related to surface tension and ionic conductivity. • Heterogeneous solid liquid acoustic cavitation controls the kinetics of H 2 production by sono-electrolysis using nickel foam. • Continuous sono-electrolysis using KOH and nickel foam leads to 64% reductio of the bubble resistance. • Continuous sonication is the optimal mode in sono-electrolysis, both kinetically and energetically. [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]

Non-noble metal electrocatalysts for the oxygen evolution reaction (OER) have recently gained particular attention. In the present work, a facile one-step electrodeposition method is applied in situ to synthesize cobalt sulfide nanostructures on nickel foam (NF) electrodes. For the first time, a systematic study is carried out on the impact of the Co/S molar ratio on the structural, morphological, and electrochemical characteristics of Ni-based OER electrodes by employing Co(NO3)2·6 H2O and CH4N2S as Co and S precursors, respectively. The optimum performance was obtained for an equimolar Co:S ratio (1:1), whereas sulfur-rich or Co-rich electrodes resulted in an inferior behavior. In particular, the CoxSy@NF electrode with Co/S (1:1) exhibited the lowest overpotential value at 10 mA cm−2 (0.28 V) and a Tafel slope of 95 mV dec−1, offering, in addition, a high double-layer capacitance (CDL) of 10.7 mF cm−2. Electrochemical impedance spectroscopy (EIS) measurements confirmed the crucial effect of the Co/S ratio on the charge-transfer reaction rate, which is maximized for a Co:S molar ratio of 1:1. Moreover, field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) were conducted to gain insights into the impact of the Co/S ratio on the structural and morphological characteristics of the electrodes. Notably, the CoxSy@NF electrocatalyst with an equimolar Co:S ratio presented a 3D flower-like nanosheet morphology, offering an increased electrochemically active surface area (ESCA) and improved OER kinetics. [ABSTRACT FROM AUTHOR]

A multiscale model has been used to optimize the microstructure of a classical hydrogen electrode made of nickel and yttria‐stabilized zirconia (Ni‐8YSZ). For this purpose, a 3D reconstruction of a reference electrode has been obtained by X‐ray nano‐holotomography. Then, a large dataset of synthetic microstructures has been generated around this reference with the truncated Gaussian random field method, varying the ratio Ni/8YSZ and the Ni particle size. All the synthetic microstructures have been introduced in a multiscale modeling approach to analyze the impact of the microstructure on the electrode and cell responses. The local electrode polarization resistance in the hydrogen electrode, as well as the complete cell impedance spectra, have been computed for the different microstructures. A significant performance improvement was found when decreasing the Ni particle size distribution. Moreover, an optimum has been identified in terms of electrode composition allowing the minimization of the cell polarization resistance. The same methodology has been also applied to assess the relevance of graded electrodes. All these results allow a better understanding of the precise role of microstructure on cell performances and provide useful guidance for cell manufacturing. [ABSTRACT FROM AUTHOR]

[Display omitted] Two-step water electrolysis has been proposed to tackle the ticklish H 2 /O 2 mixture problems in conventional alkaline water electrolysis recently. However, low buffering capacity of pure nickel hydroxide electrode as redox mediator limited practical application of two-step water electrolysis system. A high-capacity redox mediator (RM) is urgently needed to permit consecutive operation of two-step cycles and high-efficiency hydrogen evolution. Consequently, a high mass-loading cobalt-doped nickel hydroxide/active carbon cloth (NiCo-LDH/ACC) RM is synthesized via a facile electrochemical method. The proper Co doping can apparently enhance the conductivity and simultaneously remain the high-capacity of the electrode. Density functional theory results further confirms more negative values in redox potential of NiCo-LDH/ACC than Ni(OH) 2 /ACC on account of the charge redistribution induced by Co doping, which can prevent the parasitic O 2 evolution on RM electrode during decoupled H 2 evolution step. As a result, the NiCo-LDH/ACC combined the superiorities of high-capacity Ni(OH) 2 /ACC and high-conductivity Co(OH) 2 /ACC, and the NiCo-LDH/ACC with 4:1 ratio of Ni to Co presented a large specific capacitance of 33.52F/cm2 for reversible charge–discharge and high buffering capacity with two-step H 2 /O 2 evolution duration of 1740 s at 10 mA/cm2. The necessary input voltage (2.00 V) of the whole water electrolysis was broken into two smaller ones, 1.41 and 0.38 V, for H 2 and O 2 production, respectively. NiCo-LDH/ACC provided a favorable electrode material for the practical application of two-step water electrolysis system. [ABSTRACT FROM AUTHOR]

The process of argon arc welding of nickel onto titanium with a nonconsumable electrode with feeding of the nickel filler wire into the liquid metal pool is investigated. The influence of the welding modes on the geometrical parameters of the bead and on the susceptibility of the forming surface layer to crack formation is described. The effect of the welding modes on the chemical and phase compositions of the formed surface layer of titanium nickelide is determined. The chemical and phase compositions of the welded-on layer are shown to affect its hardness and wear resistance. [ABSTRACT FROM AUTHOR]

In the face of current energy and environmental challenges, electrochemical storage devices emerge as a promising alternative. Specifically, supercapacitors are highly valued for their exceptional ability to deliver rapid responses and exhibit high-power capabilities. Although rare-earth compounds have received less attention in the electrochemical storage field, the utilization of nanotechnology tools allows for precise manipulation of their shape and size, which opens new possibilities for developing novel configurations with improved properties, presenting previously unexplored applications. Herein, we set a new electrode material consisting of nanospheres of gadolinium vanadate (GdVO4) synthesized by microwave-assisted hydrothermal method, which was a crucial component in preparing nickel foam-based electrodes. The material was thoroughly characterized, revealing interesting properties for energy storage applications. The electrode delivered a high specific capacitance of 1203.75 F g−1 at 1 A g−1 and good cycling stability after 500 cycles. Then, an asymmetric supercapacitor was performed, reaching 80.63 F g−1 at 1 A g−1 and 130.2 Wh kg−1 of energy density when the power density was 2880.18 W kg−1. Thus, this study highlights the potential of GdVO4 as an electrode material in electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

Cholesterol (CH) is a vital diagnostic marker for a variety of diseases, making its detection crucial in biological applications including clinical practice. In this work, we report the synthesis of tin oxide-polyaniline nanocomposite-modified nickel foam (SnO2-PANI/NF) for non-enzymatic detection of CH in simulated human blood serum. SnO2 was synthesized via the hydrothermal method, followed by the synthesis of SnO2-PANI nanocomposite through in situ chemical polymerization of aniline using ammonium persulfate as the oxidizing agent. Morphological studies display agglomerated SnO2-PANI, which possess diameters ranging from an average particle size of ∼50 to ∼500 nm, and the XRD analysis revealed the tetragonal structure of the SnO2-PANI nanocomposite. Optimization studies demonstrating the effect of pH and weight percentage are performed to improve the electrocatalytic performance of the sensor. The non-enzymatic SnO2-PANI/NF sensor exhibits a linear range of 1–100 μ M with a sensitivity of 300 μ A μ M−1/cm−2 towards CH sensing and a low limit of detection of 0.25 μ M (=3 S m−1). SnO2-PANI/NF facilitates the electrooxidation of CH to form cholestenone by accepting electrons generated during the reaction and transferring them to the nickel foam electrode via Fe (III)/Fe (IV) conversion, resulting in an increased electrochemical current response. The SnO2-PANI/NF sensor demonstrated excellent selectivity against interfering species such as Na+, Cl−, K+, glucose, ascorbic acid, and SO42−. The sensor successfully determined the concentration of CH in simulated blood serum samples, demonstrating SnO2-PANI as a potential platform for a variety of electrochemical-based bioanalytical applications. [ABSTRACT FROM AUTHOR]

Self-heteroatom-doped N-carbon dots (N-CDs) with a 2.35 eV energy gap and a 65.5% fluorescence quantum yield were created using a one-step, efficient, inexpensive, and environmentally friendly microwave irradiation method. FE-SEM, EDX, FT-IR, XRD, UV–VIS spectroscopy, FL spectroscopy, and CV electrochemical analysis were used to characterise the produced heteroatom-doped N-CDs. The graphitic carbon dot surface is doped with heteroatom functional groups such (S, P, K, Mg, Zn) = 1%, in addition to the additional passivating agent (N), according to the EDX surface morphology and the spontaneous heteroatom doping was caused by the heterogeneous chemical composition of pumpkin seeds. These spontaneous heteroatom-doped N-CDs possess quasispherical amorphous graphitic structure with an average size of less than 10 nm and the interplaner distance of 0.334 nm. Calculations utilising cyclic voltammetry showed that the heteroatom-doped N-CDs placed on nickel electrodes had a high specific capacitance value of 1044 F/g at a scan rate of 10 mV/s in 3 M of KOH electrolyte solution. Furthermore, it demonstrated a high energy and power density of 28.50 Wh/kg and 3350 W/kg, respectively. The higher value of specific capacitance and energy density were attributed to the fact that the Ni/CDs electrode material possesses both EDLC and PC properties due to the sufficient surface area and the multiple active sites of the prepared N-CDs. Furthermore, the heteroatom N-CDs revealed the antifungal action and bioimaging of the "Cladosporium cladosporioides" mould, which is mostly accountable for economic losses in agricultural products. The functional groups of nitrogen, sulphur, phosphorus, and zinc on the surface of the CDs have strong antibacterial and antifungal properties as well as fluorescence enhanced bioimaging. [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]

Theophylline is a drug with a narrow therapeutic range. Electrochemical sensors are a potentially effective method for detecting theophylline concentration to prevent toxicity. In this work, a simple modification of a boron-doped diamond electrode using nickel nanoparticles was successfully performed for a theophylline electrochemical sensor. The modified electrode was characterized using a scanning electron microscope and X-ray photoelectron spectroscopy. Square wave voltammetry and cyclic voltammetry methods were used to study the electrochemical behavior of theophylline. The modified nickel nanoparticles on the boron-doped diamond electrode exhibited an electrochemically active surface area of 0.0081 cm2, which is larger than the unmodified boron-doped diamond's area of 0.0011 cm2. This modified electrode demonstrated a low limit of detection of 2.79 µM within the linear concentration range from 30 to 100 µM. Moreover, the modified boron-doped diamond electrode also showed selective properties against D-glucose, ammonium sulfate, and urea. In the real sample analysis using artificial urine, the boron-doped diamond electrode with nickel nanoparticle modifications achieved a %recovery of 105.10%, with a good precision of less than 5%. The results of this work indicate that the developed method using nickel nanoparticles on a boron-doped diamond electrode is promising for the determination of theophylline. [ABSTRACT FROM AUTHOR]

Direct seawater electrolysis provides a grand blueprint for green hydrogen (H2) technology, while the high energy consumption has severely hindered its industrialization. Herein, a promising active site implantation strategy is reported for Ni(OH)2 nanowire network electrode on nickel foam substrate by Ru doping (denoted as RuNi(OH)2 NW2/NF), which can act as a dual‐function catalyst for hydrazine oxidation and hydrogen evolution, achieving an ultralow working potential of 114.6 mV to reach 1000 mA cm−2 and a small overpotential of 30 mV at 10 mA cm−2, respectively. Importantly, using the two‐electrode hydrazine oxidation assisted seawater electrolysis, it can drive a large current density of 500 mA cm−2 at 0.736 V with over 200 h stability. To demonstrate the practicability, a home‐made flow electrolyzer is constructed, which can realize the industry‐level rate of 1 A cm−2 with a record‐low voltage of 1.051 V. Theoretical calculations reveal that the Ru doping activates Ni(OH)2 by upgrading d‐band centers, which raises anti‐bonding energy states and thus strengthens the interaction between adsorbates and catalysts. This study not only provides a novel rationale for catalyst design, but also proposes a feasible strategy for direct alkaline seawater splitting toward sustainable, yet energy‐saving H2 production. [ABSTRACT FROM AUTHOR]

In this study, we present a novel electrode material that combines Ti 3 C 2 MXene and high-capacity CuMn 2 O 4 to increase the energy density of supercapacitors, which are a popular choice for energy storage due to their high-performance potential. The electrode material was synthesized using the hydrothermal method with varying deposition times (3 h, 6 h and 9 h), and the resulting composite materials were characterized using advanced analytical techniques. The CuMn 2 O 4 /MXene composite electrode synthesized at 3h exhibited exceptional performance, with a specific capacitance of 628 mF/cm2 at 4 mA/cm2, due to the enhanced electrical conductivity and charge storage properties of CuMn 2 O 4 and MXene sheets. We also uncovered an intricate charge transfer mechanism and storage kinetics of CuMn 2 O 4 /MXene composite on a nickel foam electrode, revealing a diffusion-controlled energy storage mechanism with fast mass transportation. To demonstrate practicality, we constructed an asymmetric coin cell supercapacitor device using CuMn 2 O 4 /MXene composite synthesized at 3h and activated carbon as the positive and negative electrodes, respectively. The device showed a specific capacitance of 496 mF/cm2 at 6 mA/cm2 with cyclic stability of 80% for up to 10,000 cycles, and a power density of 1.5 mW/cm2 at a higher energy density of 0.073 mWh/cm2. Our results demonstrate the potential to significantly advance the development of high-performance supercapacitors by combining Ti 3 C 2 MXene and high-capacity oxides, refining the synthesis process, and exploring innovative electrode architectures. [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]

Neutral water oxidation is a crucial half‐reaction for various electrochemical applications requiring pH‐benign conditions. However, its sluggish kinetics with limited proton and electron transfer rates greatly impacts the overall energy efficiency. In this work, we created an electrode/electrolyte synergy strategy for simultaneously enhancing the proton and electron transfers at the interface toward highly efficient neutral water oxidation. The charge transfer was accelerated between the iridium oxide and in situ formed nickel oxyhydroxide on the electrode end. The proton transfer was expedited by the compact borate environment that originated from hierarchical fluoride/borate anions on the electrolyte end. These concerted promotions facilitated the proton‐coupled electron transfer (PCET) events. Due to the electrode/electrolyte synergy, Ir−O and Ir−OO− intermediates could be directly detected by in situ Raman spectroscopy, and the rate‐limiting step of Ir−O oxidation was determined. This synergy strategy can extend the scope of optimizing electrocatalytic activities toward more electrode/electrolyte combinations. [ABSTRACT FROM AUTHOR]

[1][4] Since the first development of transition-metal-catalyzed addition reactions of buta-1,3-diene with diverse nucleophiles in 1976, more and more chemists have focused on the functionalization of buta-1,3-diene catalyzed by transition metals. Keywords: electrochemical reduction; trans -olefins; 1,3-dienes; alkyl halides; radicals EN electrochemical reduction trans -olefins 1,3-dienes alkyl halides radicals 3033 3039 7 08/31/23 20230915 NES 230915 Graph Buta-1,3-diene is of great importance in pharmaceuticals and chemical industry with an annual output over 10 million tons, which serves as a basic synthetic motif for terpene natural products. Finally, a cyclic alkyl iodide containing the I N i -Boc group could be reduced to a free radical in the electrochemical reduction system, and the target product was readily obtained by the addition reaction with buta-1,3-diene ( B 3l b ). Free radicals could be obtained by visible-light-induced photoredox processes, and then reacted with 1,3-diene derivatives to obtain free radical intermediates by 1,2- and 1,4-addition, followed by radical capture to give multicomponent products. [Extracted from the article]

In this study, Ni 3 (benzene 1,3,5-tricarboxylic acid)@polyaniline-rGO nanocomposite (Ni-MOF@PANI-rGO) is fabricated by a two-step procedure involving polymerization and hydrothermal operations. This nanocomposite-based Ni-MOF was designed for binder-free surface modification of nickel foam (NF). This is offered a novel approach for enhancing the electrochemical performance, and even energy density with a wider operating potential window. An in-situ Ni-MOF was then synthesized on polyaniline@GO (PANI-GO) using an NH-fragment linker and an in-situ hydrothermal technique. The electrochemical behavior of the nanocomposite was studied in asymmetric systems and exhibited outstanding electrochemical performance, high energy density, and power density (73.99 Wh kg−1 at 848.29 W kg−1). The electrode also showed a high specific capacity (1680 C g−1 at 1.0 A g−1) and exceptional cycling stability (92⁒) after 5000 cycles in a three-electrode system. The present results imply a direct application of Ni-MOF@PANI-rGO composite as a bridge performance between supercapacitors and batteries. In addition, the electrocatalyst activity of Ni-MOF@PANI-rGO toward hydrogen evolution reaction (HER) was investigated by linear sweep voltammetry at a scan rate of 10 mV s−1 in 1.0 M KOH. The results showed that Ni-MOF@PAN-rGO acts as a suitable electrocatalyst with the lowest overpotential at 10, 50, and 80 mA cm−2 and the lowest Tafel slope. [Display omitted] • A binder-free engineering design current collector electrode is introduced. • An in-situ Ni-MOF was then synthesized on PANI-rGO using an NH-fragment linker. • Ni 3 (BTC)@PANI-rGO nanocomposite exhibited good behavior for supercapacitor application and HER. • The nanocomposite showed high energy density and power density (132 Wh kg−1 at 1500 W kg−1). • Ni 3 (BTC)@PANI-rGO acts as a suitable electrocatalyst lowest overpotential and Tafel slope. [ABSTRACT FROM AUTHOR]

[Display omitted] Flexible supercapacitors have received considerable attention for their potential application in flexible electronics, but usually suffer from relatively low energy density. Developing flexible electrodes with high capacitance and constructing asymmetric supercapacitors with large potential window has been considered as the most effective approach to achieve high energy density. Here, a flexible electrode with nickel cobaltite (NiCo 2 O 4) nanowire arrays on nitrogen (N)-doped carbon nanotube fiber fabric (denoted as CNTFF and NCNTFF, respectively) was designed and fabricated through a facile hydrothermal growth and heat treatment process. The obtained NCNTFF-NiCo 2 O 4 delivered a high capacitance of 2430.5 mF cm−2 at 2 mA cm−2, a good rate capability of 62.1 % capacitance retention even at 100 mA cm−2 and a stable cycling performance of 85.2 % capacitance retention after 10,000 cycles. Moreover, the asymmetric supercapacitor constructed with NCNTFF-NiCo 2 O 4 as positive electrode and activated CNTFF as negative electrode exhibited a combination of high capacitance (883.6 mF cm−2 at 2 mA cm−2), high energy density (241 μW h cm−2) and high power density (80175.1 μW cm−2). This device also had a long cycle life after 10,000 cycles and good mechanical flexibility under bending conditions. Our work provides a new perspective on constructing high-performance flexible supercapacitors for flexible electronics. [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]

Light rare earth (LRE3+) ions‐doped Ta2O5 semiconductor material is synthesized via coprecipitation method with the bandgap energy of 3.94–4.05 eV and an orthorhombic geometry with 74.49 nm size. The rare earth‐modified Ta2O5 improves the photovoltaic functionality of the fully ambient perovskite solar cell by efficient extraction of electrons and blocking of the holes. The device achieved an efficiency of 13.36% with 63% of fill factor and negligible hysteresis index. LRE3+ triply doped Ta2O5 is used for the fabrication of an electrode by decorating on the nickel foam. This electrode outperforms the conventionally used materials by achieving a specific capacitance of 517.5 F g−1 marked by fast reaction kinetics and diffusion with an equivalent series resistance of 0.18 Ω. LRE3+‐doped Ta2O5 is proved to be an excellent electrode material with the characteristic electric double‐layer capacitance behavior in conjugation with the Faradic pseudocapacitive behavior. Finally, the electrocatalysis using this material indicates its excellence as a H2 generating catalyst in comparison to O2 generation with the smallest overpotential and Tafel slope values of 143 mV and 125.3 mV dec−1, respectively. The designed electrode expressed an exceptional stability over ambient conditions as well as inside an electrolyte. [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]

The demand for power storage devices with good quality, fast charging and high energy density is becoming more and more urgent in today's electronic technology. For batteries and traditional capacitors, it is an insurmountable challenge to combine fast charging and discharging, large capacitance and long-life properties. The characteristics of supercapacitors can meet all the above requirements at the same time. In this study, a simple one-step hydrothermal method was successfully used to grow β-nickel hydroxide nanocone particles directly on the 3D foamed nickel substrate as a working electrode material for supercapacitors. After growing β-nickel hydroxide crystals on 3D foamed nickel substrate, by controlling the cooling rate, a well-crystalized β-nickel hydroxide with good capacitance characteristics can be obtained. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) were used to analyze the capacitance characteristics of the β-nickel hydroxide electrode. The research results show that the specific capacitance value of the β-Ni(OH)2/3D nickel foam electrode material prepared at the cooling rate of 10 °C/h can reach 539 F/g with the charge–discharge test at a current density of 3 A/g. After 1000 continuous charge and discharge cycles, the material still retains 94.1% of the specific capacitance value. [ABSTRACT FROM AUTHOR]

Pepper processing is one of the largest productions that significantly contribute (98%) to Sarawak, Malaysia's economic and agricultural sectors. The prolonged retting process of pepper berries would cause undesirable dark colour and acidic wastewater. This study aims to evaluate the performance of an electrocoagulation treatment using nickel and copper electrodes for the changes in turbidity and pH of pepper wastewater. Some analyses (correlation studies and kinetic modelling) were studied. The electrocoagulation treatment was conducted by having two conditions nickel and copper electrodes immersed in 400 mL of pepper wastewater for 30 minutes. Every 5 minutes, it was monitored, and the sample was taken for further analysis. The results indicated a significant decrease in the turbidity of pepper wastewater for nickel (98.25%) and copper electrodes (86.32%) was noticed with the increase in the electrocoagulation treatment time. At the same time, the pH values for nickel and copper electrodes were increased by 27.43% and 31%, respectively. The results were evaluated by using Principal Component Analysis (PCA). PCA describes the correlation between the wastewater qualities in this study within less time. Among four models (zero, first and second-order) applied in this study, the turbidity for nickel and copper electrodes had the highest R² values (0.9457 and 0.9899) in the zero-order model. For pH, the second-order model had the highest R² values (0.9508 and 0.9657) for nickel and copper electrodes. Electrocoagulation using nickel and process electrodes is a practical method to treat pepper wastewater. [ABSTRACT FROM AUTHOR]

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Co-reduction of lanthanum and nickel ions on inert tungsten and active nickel electrodes were studied using the methods of cyclic chronovoltammetry, chronopotentiometry and open circuit chronopotentiometry in equimolar KCl–NaCl at 973 K. When both lanthanum and nickel ions are present in equimolar KCl–NaCl, the voltammetry dependences demonstrate the nickel ions reduction wave in the region of potentials –(0.00–0.1) V and lanthanum ions reduction wave in the region of potentials –(1.85–1.9) V relative to a silver chloride reference electrode. There are two more reduction waves on the opposite sides of voltammograms in the regions of potentials –(1.5–1.6) V and –(1.75–1.8) V. These waves are associated with the reduction of lanthanum ions and their depolarization on metallic nickel preliminarily deposited on the tungsten electrode, which results in the formation of intermetallic La x Ni y phases. The (E–t) dependences of open circuit chronopotentiometry demonstrate a delay plateau, which corresponds to the time required for dissolution of separate phases of intermetallic compounds. LaNi 2 and LaNi 5 intermetallic phases were electrochemically synthesized at a definite concentration of lanthanum and nickel chlorides in equimolar KCl–NaCl. The synthesized lanthanum and nickel intermetallic compounds were characterized by the X-ray diffraction analysis, scanning electron microscopy and photon correlation spectroscopy. • Co-reduction of La3+ and Ni2+ has been first performed in equimolar KCl–NaCl. • La x Ni y is synthesized under kinetic regime due to difference in La and Ni deposition potentials. • La x Ni y intermetallic phases can be synthesized by potentiostatic electrolysis. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) exhibit many structural advantages, such as large specific surface area and abundant active sites, which make them promising candidates as electrode materials for non-enzymatic glucose sensors. In this work, using MOFs as templates, MOFs derived Co 3 O 4 nanoparticles (NPs) were in-situ synthesized on the surface of NiCo 2 O 4 nanowires (NWs), forming a self-supporting electrode based on nickel foam (NF), which was directly used for the detection of glucose. Because of the presence of MOFs derivatives and self-supporting structures, NF/NiCo 2 O 4NWs @Co 3 O 4NPs electrode exhibits good structural stability and high conductivity, which ensure the excellent electrocatalytic performance. The NF/NiCo 2 O 4NWs @Co 3 O 4NPs electrode shows prominent electrocatalytic performance toward glucose with a wide testing range (0.001–1.7 mmol/L), high sensitivity (8163.2 μA cm−2 mM−1), fast response time (within 1 s), high anti-interference ability and long-term stability. Further, the electrode was used to test different glucose levels in live mouse serum samples, showing acceptable reliability and high accuracy comparing with blood glucose meter test (medical test method). Thus, NF/NiCo 2 O 4NWs @Co 3 O 4NPs electrode with self-supporting core-shell nanostructure will be a promising candidate applied in non-enzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

Supercapacitors (SCs) are currently numbered among the most outstanding energy storage and supply devices due to their high power density, durable cycle life, and wide operating temperature range. However, the wide application of SCs is still subject to the low energy density, which drives researchers to extensively look for high-performance electrode materials. In recent years, nickel sulfide-based materials have been widely studied as promising electrode materials for SCs due to their superior theoretical specific capacity, high redox activity, and rapid electric conduction, but the inferior active material utilization efficiency and poor reaction kinetics limit their practical demand in SCs. In this review, we briefly introduced the energy storage mechanism of nickel sulfide electrode materials used in supercapacitors and then launched an overview of improving performance. A particular emphasis is on the modification strategies to accelerate the electron conduction and mass transfer process through carbon recombination, metal heteroatom doping, interfacial electric field construction, exposure of edge active sites and large specific surface area, and building of ion diffusion channels. Finally, we discuss the research orientation of nickel sulfide-based electrode materials. [ABSTRACT FROM AUTHOR]

Lithium-ion battery cells exhibit a complex and nonlinear coupling of thermal, electrochemical, and mechanical behavior. In order to increase insight into these processes, we report the development of a pseudo-three-dimensional (P3D) thermo-electro-mechanical model of a commercial lithium-ion pouch cell with graphite negative electrode and lithium nickel cobalt aluminum oxide/lithium cobalt oxide blend positive electrode. Nonlinear molar volumes of the active materials as function of lithium stoichiometry are taken from literature and implemented into the open-source software Cantera for convenient coupling to battery simulation codes. The model is parameterized and validated using electrical, thermal and thickness measurements over a wide range of C-rates from 0.05 C to 10 C. The combined experimental and simulated analyses show that thickness change during cycling is dominated by intercalation-induced swelling of graphite, while swelling of the two blend components partially cancel each other. At C-rates above 2 C, electrochemistry-induced temperature increase significantly contributes to cell swelling due to thermal expansion. The thickness changes are nonlinearly distributed over the thickness of the electrode pair due to gradients in the local lithiation, which may accelerate local degradation. Remaining discrepancies between simulation and experiment at high C-rates might be attributed to lithium plating, which is not considered in the model at present. [ABSTRACT FROM AUTHOR]

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]

Suitable transitional metal electrode substrate should keep high electroactivity and meanwhile suppress polarization effect. Theoretical calculation and experimental measurement are adopted to investigate interfacial interaction-dependent capacitance of lithium perchlorate-titanium and nickel (LiClO4-Ti, LiClO4-Ni) metal substrates. LiClO4-Ti reveals ideal electrical double layer capacitance due to electrochemical stability and LiClO4-Ni reveals the deviated electrical double layer capacitance due to polarization effect in potential range of 0–0.8 V. LiClO4-Ni reveals lower ohmic resistance, charge transfer resistance and Warburg resistance to present higher conductivity, more active interface, and more feasible ion diffusion properties than LiClO4-Ti. Titanium and nickel substrates achieve mean response current of 0.13–2.47 μA cm−2 and 1.03–22.20 μA cm−2 at 5200 mV s−1. The corresponding specific capacitances are 0.010–0.0095 mF cm−2 and 0.322–0.155 mF cm−2 at 0.01–0.10 mA cm−2. LiClO4-Ni keeps much higher capacitance but relatively lower electrochemical stability than LiClO4-Ti. Theoretical calculation proves interfacial electrostatic adsorption of LiClO4 on Ti and Ni substrates could change charge density distribution. LiClO4-Ni with the enlarged potential difference causes intensified polarization effect. LiClO4-Ni exhibits higher electrical conductivity and lower interface energy than LiClO4-Ti. Furthermore, carbon-coated nickel (C@Ni) was prepared to mostly restrain polarization effect and meanwhile keep high electroactivity of Ni substrate for the promising supercapacitor electrode application. It reveals specific capacitance of 25.9 mF cm−2 and cycling capacitance retention of 94.5% after 1000 charge-discharge cycles at 1.0 mA cm−2 in 1.0 M LiClO4. The C@Ni electrode accordingly exhibits superior electroactivity and electrical double layer capacitance for energy storage application. [ABSTRACT FROM AUTHOR]

The core–shell NiS 2 @C encapsulated by thin hydrothermal carbon (HC) layer (NiS 2 @C/HC) has been designed and prepared without any surfactants or templates assistance, which exhibits high-rate and durable stability for aqueous rechargeable battery. [Display omitted] Nickel sulfides, as promising candidate for aqueous rechargeable battery, have aroused broad attention on account of abundant natural resources, rich phases, moderate price and high theoretical capacity. Nevertheless, tremendous volume expansion during repeated charging-discharging procedure leads to the poor rate capability and cycling stability of nickel sulfide electrodes. Therefore, in this work, core–shell NiS 2 @C encapsulated by thin hydrothermal carbon (HC) layer (NiS 2 @C/HC) has been designed and prepared without any surfactants or templates assistance, which avoid tedious process and shorten preparation cycle greatly. When matched with the treated iron powder (TIP) electrode to form NiS 2 @C/HC//TIP aqueous rechargeable battery, the NiS 2 @C/HC//TIP battery exhibits a high discharge capacity of 205.1 mAh g−1 at 1 A g−1, remarkable rate ability (176.4 mAh g−1 at 5 A g−1, about 86% capacity conversation) and superiorly durable stability (80.8 % capacity retention after 10,000 cycles at ultra-high current density of 15 A g−1). The outstanding high-rate capability and cycling stability for aqueous rechargeable battery can be ascribed to the distinct cowpea-like architecture and intrinsic properties of NiS 2 @C/HC. Specifically, the interior porous carbon provides a space to tolerate the volume expansion of the NiS 2 nanoparticles and prevent NiS 2 nanoparticles from aggregation, guaranteeing its high-rate capability. Meanwhile, the exterior HC layer is conducive to improve the electric conductivity to facilitate the electrons transfer and promote the mechanical strength of the whole active materials, ensuring its robust cycling stability. [ABSTRACT FROM AUTHOR]

Electrochemically durable perovskite electrodes of nickel foam/TiO2/FA(Pb1−xGex)I3, passivated using various surfactants of tetra-n-alkyl ammonium halides (alkyl = ethyl, butyl, hexyl, or octyl; halide = I, I0.5Br0.5, Br, Br0.5Cl0.5, or Cl), were successfully applied as good electro-catalysts on the counter electrodes in dye-sensitized solar cells (DSSCs). The longer alkyl chain of a surfactant resulted in a higher water contact angle, but poorer film conductivity. Based on the optimal tetra-n-hexyl ammonium (THA) cation, shrinking the halide radius of THA from I to I0.5Br0.5 formed an appropriate amount of FAPbBr3 nano-crystals covering on the FA(Pb1−xGex)I3 grain surface. This phenomenon not only suppressed the perovskite decomposition under electrochemical measurements, but also created additional electro-catalytic active sites for triggering the iodide/triiodide redox reaction. Further shrinking the halide radius of THA from I0.5Br0.5 to Cl resulted in a severe self-aggregation of THACl, leading to an insufficient passivation and thereby poor electrochemical performance. In an ambient environment with a relative humidity higher than 75%, the optimal perovskite electrode of nickel foam/TiO2/FA(Pb1−xGex)I3-THAI0.5Br0.5 maintained the good crystallinity of α-FAPbI3 at least for 6 months, without obvious decomposition. Compared to the DSSC couple with a common counter electrode of nickel foam/Pt (8.74%), a better cell performance of 8.87% was achieved using the counter electrode of nickel foam/TiO2/FA(Pb1−xGex)I3-THAI0.5Br0.5, which was attributed to its good intrinsic electro-catalytic activity, large surface area, multiple active sites, and decent thermodynamic stability. Under room light illumination, higher cell efficiencies were obtained at 1 klux (21.5% for an office), 3 klux (22.9% for a shopping window), and 6 klux (22.3% for a lampshade). There is no doubt that air-stable perovskites have great potential in showing high performance for various electrochemical devices. [ABSTRACT FROM AUTHOR]

Plastic waste is a serious environmental issue, and polyethylene (PE) is a significant component. The chemically inert nature of PE makes its recycling/upcycling process challenging. Thus, a novel method was demonstrated that enables the selective electrochemical functionalization and deconstruction of low‐density polyethylene (LDPE) by using low‐cost transition metal electrocatalysts at room temperature (23±2 °C) and low cell voltage (±1 V). Three different electrode and electrolyte combinations were studied for the oxidation of LDPE: copper metal/copper (II) ions, nickel metal/nickel (II) ions, and stainless steel/iron (II) and (III) ions. The copper and nickel electrode/electrolyte pairs showed a promising capability for oxidation and chain‐scission of LDPE. In contrast, the stainless‐steel and iron electrode/electrolyte pair showed no activity towards LDPE oxidation or depolymerization. The electrolysis of LDPE offers a new vista for the depolymerization and upcycling of plastics, further understanding of the process is needed. [ABSTRACT FROM AUTHOR]

Poly(3,4-ethylenedioxythiophene) (PEDOT) was electrosynthesized on nickel electrodes from aqueous micellar solutions of sodium dodecylbenzenesulfonate (SDBS) containing sodium saccharin or sodium perchlorate as supporting electrolytes. The choice of the aqueous medium for the preparation of PEDOT is mainly dictated by its relevant interest on the economic and ecological fronts. The electrodeposition of the organic coating was achieved using cyclic voltammetry, chronoamperometry and chronopotentiometry. This latter electrochemical method proved to be the most suited to the preparation of homogeneous and adherent PEDOT films. Elsewhere, the presence of SDBS micelles in the electrolytic medium led to an improvement of the monomer solubility and a notable decrease in its oxidation potential. Furthermore, spectroscopic and microscopic characterization techniques revealed regular and compact nodule-like structure of the coating and proved the increase in its doping rate when increasing the electrosynthesis current density. On the other hand, in order to discuss the potential application of the prepared conducting polymer as protective layer against corrosion, several electrochemical tests were performed, using open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) methods. OCP curves have shown a slight increase in the potential toward more positive values, while the EIS measurements have given a 90° capacitive line indicating the pure capacitive behavior of the polymeric system and have proven the presence of a fast charge transfer at the metal/polymer and polymer/solution interfaces. [ABSTRACT FROM AUTHOR]

Advances in wearable bioelectronics enable the possibility of transforming the currently reactive and disease-centric healthcare system to one focused on disease prevention and health promotion. Converting biomechanical activities into electrical signals could be a unique way to develop wearable bioelectronics for personalized healthcare. In this work, an air-permeable textile (APT) bioelectronics is developed. It is formed with a liquid metal electrode treated with Nickel (Ni-EGaIn) encapsulated between two layers of electrospun Polycaprolactone textile. With a size of 4 cm by 4 cm, the APT bioelectronics produces an open-circuit voltage of 12 V and a short-circuit current of 0.12 mA, ultimately outputting a power density of 7.975 W m-2. The APT bioelectronics demonstrates an ability to produce electrical output under varying degrees of deformation with stable performance over 6000 cycles. In addition, the APT bioelectronics holds a drying rate of 5.07% min-1 compared to conventional fabrics such as polyester with a drying rate of 3.93% min-1. This keeps the ATP dry and cool for decent wearing comfort. With a collection of compelling features, the air-permeable textile bioelectronics represents a promising approach for human body centered energy and sensing applications. [ABSTRACT FROM AUTHOR]