Nickel Hydroxide Research Articles

Intelligently constructing polyaniline/Nickel hydroxide core-shell nanoflowers as anode for flexible electrode-enhanced lithium/sodium ion batteries

Abstract The intelligent design of advanced anode materials plays a pivotal role in energy storage for lithium-ion (LIBs) and sodium-ion batteries (SIBs), and offering potential for broadening their practical applications through the development of flexible electrodes. In this study, Nickel hydroxide nanoflowers grown on Ni foam (Ni(OH)2 NFs/NF) was synthesized by hydrothermal method. Subsequently nickel hydroxide nanoflowers-polyaniline (Ni(OH)2 NFs/PANI) was synthesized by electrodeposition method. Ni(OH)2 NFs/NF and Ni(OH)2 NFs/PANI can be straightforwardly utilized as pliable electrodes. For the first discharge capacity, Ni(OH)2 NFs/PANI electrode delivers higher capacity (1608.1 mAh g−1) than Ni(OH)2 NFs/NF (1464.1 mAh g−1) for LIBs. For the first discharge capacity, Ni(OH)2 NFs/PANI electrode delivers more superior capacity (473.4 mAh g−1) than Ni(OH)2 NFs/NF (406.6 mAh g−1) for SIBs. Ni(OH)2 NFs/PANI electrode demonstrated enhanced rate performance and cycling stability in comparison to Ni(OH)2 NFs/NF electrode.

Role of synthetic process parameters of nano-sized cobalt/nickel oxide in controlling their structural characteristics and electrochemical energy performance as supercapacitor electrodes

The synthesis of nano-sized bimetallic Cobalt/Nickel oxides (Ni1.5Co1.5O4) with a 1:1 Co/Ni atomic ratio has been achieved using a surfactant-free co-precipitation/hydrothermal process. The growth mechanism of Cobalt/Nickel oxides Ni1.5Co1.5O4 is elucidated by tuning the synthesis process parameters, including co-precipitation pH and hydrothermal time. The formation of Cobalt/Nickel oxides Ni1.5Co1.5O4 oxide began with the nucleation of cobalt nickel hydroxide nanoplates through the co-precipitation process, followed by dissolution-recrystallization, stacked hexagonal nano-flakes, and a flower-like microstructure. The electrochemical performances of the oxides were evaluated, with the largest surface area observed at pH 9 being the main factor for the best super-capacitive performance. As hydrothermal time increased, the structural directing growth forward, resulted in the formation of a nano-flower structure with a larger surface area. The as-prepared cobalt nickel oxide exhibited a maximum specific capacitance value of 525.5 F g-1 at a current density of 1 A g-1 and energy and power densities of 88.2 WhKg-1 and 606 WKg-1, respectively.

Facilitating the electrooxidation of 5-hydroxymethylfurfural on nickel hydroxide through deintercalation

The electrocatalytic of 5-hydroxymethylfurfural oxidation reaction (HMFOR) is an alternative route for the green production of valuable oxygenated chemicals. Nickel hydroxides, which consist of hydroxide layers and interlayer charge-balancing anions, are a type of promising catalysts for HMFOR. Progresses have been made on elucidating the correlation between the hydroxide layer and HMFOR performance, while the effect of intercalated anions on the activity remains unclear. Herein, two self-supported nickel hydroxide catalysts (i.e., pristine Ni(OH)2/CP-F and deintercalated Ni(OH)2/CP-A) are employed for revealing the relationship between anion-deintercalation and HMFOR activity. Physical characterizations demonstrate that the deintercalation phenomenon can alter the d-band center and increase the electron density of the Ni site. This endows the deintercalated Ni(OH)2/CP-A with improved electrochemical properties (conversion = 99.99 %; FDCA yield > 99 %; FE > 99 %), enhanced adsorption strength for HMF, and increased intrinsic activity, compared to the pristine Ni(OH)2/CP-F. This work not only reports an excellent HMFOR electrocatalyst, but also manifests the crucial effect of deintercalation on the electrochemical oxidation performance of Ni(OH)2.

Tantalum-induced reconstruction of nickel sulfide for enhanced bifunctional water splitting: Separate activation of the lattice oxygen oxidation and hydrogen spillover

Designing highly active and stable bifunctional catalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) under alkaline conditions is crucial for sustainable overall water splitting. Herein, we present a targeted reconstruction of Ni3S2 by introducing tantalum, achieving remarkable overall water splitting performance through the separate activation of the lattice oxygen mechanism and hydrogen spillover. Electrochemical Mass Spectrometry and in-situ Raman spectroscopy reveal that tantalum induces Ni3S2 to reconstruct into nickel hydroxide during OER, thereby enhancing catalytic activity via the activation of the lattice oxygen mechanism. In the corresponding HER, tantalum promotes the reconstruction of Ni3S2 into oxysulfide, facilitates hydrogen spillover, and acts as an anchor to shorten the spillover distance, improving the HER catalytic performance, as verified by the kinetic isotope effect and theoretical calculations. Therefore, the catalyst-based anion exchange membrane water electrolyzer system achieves a current density of 1 A cm−2 at just 1.97 V, maintaining continuous operation for 500 h. This study offers new insights into the design of bifunctional catalysts, advancing the development of efficient and robust overall water splitting catalysts.

In-situ Electrochemical Synthesis of Ni/Ni(OH)2/Molecularly Imprinted Polymer Nanocomposite for High-Performance Glucose Detection

This study presents a novel non-enzymatic glucose sensor that synergistically combines the high catalytic activity of nickel hydroxide (Ni(OH)2) with the selective recognition of molecularly imprinted polymers (MIPs). The sensors were fabricated through an entirely in-situ synthesis directly on the electrode, comprising electrodeposition and oxidation of Ni/Ni(OH)2 nanoparticles and electropolymerization of a glucose-imprinted MIP layer using pyrrole and 3-aminophenyl boronic acid. The integrated MIP layer significantly enhanced selectivity against common interferents while amplifying glucose sensitivity. The resulting sensor demonstrated a high sensitivity of 1802 μA mM-1 cm-2 with a linear range from 0.04 to 2.6mM. Notably, the sensor exhibited remarkable stability, retaining 97.2% of its original sensitivity after 6 months of room-temperature storage. To extend the linear range, Nafion coatings at two concentrations were applied, achieving ranges up to 0.04 – 11.6mM with adjusted sensitivities. This innovative approach, leveraging MIPs to provide selectivity to electrocatalytic nanomaterials, offers a promising strategy for developing high-performance non-enzymatic sensors for glucose and other biomolecules in diabetes monitoring and beyond.

Thermal Conversion of Ultrathin Nickel Hydroxide for Wide Band Gap 2D Nickel Oxides.

Wide band gap (WBG) semiconductors (E g > 2.0 eV) are integral to the advancement of next-generation electronics, optoelectronics, and power industries owing to their capability for high-temperature operation, high breakdown voltage, and efficient light emission. Enhanced power efficiency and functional performance can be attained through miniaturization, specifically via the integration of device fabrication into a two-dimensional (2D) structure enabled by WBG 2D semiconductors. However, as an essential subgroup of WBG semiconductors, 2D transition metal oxides (TMOs) remain largely underexplored in terms of physical properties and applications in 2D optoelectronic devices, primarily due to the scarcity of sufficiently large 2D crystals. Thus, our goal is to develop synthesis pathways for 2D TMOs possessing large crystal domains (e.g., >10 μm), expanding the 2D TMO family and providing insights for future engineering of 2D TMOs. Here, we demonstrate the synthesis of WBG 2D nickel oxide (NiO) (E g > 2.7 eV) thermally converted from 2D nickel hydroxide (Ni(OH)2) with a lateral domain size larger than 10 μm. Moreover, the conversion process is investigated using various microscopic techniques, such as atomic force microscopy, Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, providing significant insights into morphology and structural variations under different oxidative conditions. The electronic structure of the converted Ni x O y is further investigated using multiple soft X-ray spectroscopies, such as X-ray absorption and emission spectroscopies.

Phase Reconstruction‐Directed Synthesis of Oxalate‐Functionalized Nickel Hydroxide Electrocatalyst for High‐Yield H2O2 Generation at Industrial Currents

AbstractThe electrochemical oxygen reduction reaction (2e− ORR) offers a promising approach for H2O2 production, yet developing highly active, selective, and stable electrocatalysts remains a challenge. In this work, a phase reconstruction strategy is presented to synthesize an oxalate‐adsorbed nickel hydroxide electrocatalyst (Ni(OH)2‐C2O4) through the self‐dissociation of nickel oxalate in an alkaline medium, leading to a notable enhancement in H2O2 yield at elevated current densities. Remarkably, Ni(OH)2‐C2O4 exhibits a 2e− selectivity exceeding 93% across a broad voltage range (0.0 to 0.5 V vs RHE) in 0.1 M KOH, outperforming pristine Ni(OH)2. When deployed as a gas diffusion electrode in a flow cell, the Ni(OH)2‐C2O4 catalyst demonstrates stable operation for 50 h at 200 mA cm−2, with a Faradaic efficiency surpassing 90% and a peak H2O2 yield of 6.2 mol g−1cat h−1. Comprehensive advanced characterizations, including in situ Raman spectroscopy, transient photovoltage spectra, and transient potential scanning spectra, coupled with post‐ORR analyses, reveal that surface‐adsorbed oxalate groups on Ni(OH)2 enhance the interfacial reaction kinetics between active Ni sites and reactants by inducing a charge trapping effect and forming a hydrogen‐bonded network, facilitating robust and high‐yield H2O2 production.

In situ regulating the interfacial work function of Ag doped Ni(OH)2 via trace of Fe2+ for efficient water splitting

Traditional approaches for tuning the water electrolysis performance of catalysts through manipulating their work function (WF) have primarily focused on the design of pre-catalysts prior to electrochemical test. Herein, an in situ interfacial WF modulation concept has been developed to synthesize the Fe modified nickel-based hydroxide electrocatalyst with enhanced OER (named as 0.168-FeO-Ag-Ni(OH)2/NF) and HER (0.168-FeH-Ag-Ni(OH)2/NF) activity. The modulator is trace amounts of Fe2+ in 1 M KOH, while the support comprises silver-modified nickel hydroxide, in which the Ag possesses a valence catalysis effect on Ni or Fe sites. Under optimized Fe2+ content, the deposition of Fe facilitates the release of the WF of Ag-Ni(OH)2/NF and accelerates the electron transfer between the catalyst and reaction intermediates. Meanwhile, the charge transfer from Fe to Ni sites coupled with the blue shift of d-band promote the adsorption of water molecules and the desorption of hydrogen protons, thereby accelerating the hydrogen evolution reaction kinetics. Consequently, the OER and HER activity of 0.168-FeO-Ag-Ni(OH)2/NF and 0.168-FeH-Ag-Ni(OH)2/NF enhanced 4.31 and 2.48 times, respectively. Notably, compared with Ag-Ni(OH)2/NF(+)//Ag-Ni(OH)2/NF(−), at a high current density of 1000 mA cm−2, the potential for energy consumption reduction of 0.168-FeO-Ag-Ni(OH)2/NF(+)//0.168-FeH-Ag-Ni(OH)2/NF(−) couple is at least 6 %, which endows it a promising application prospect in the actual electrolytic water system in the future.

Diffusion and capacitive controlled surfactant assisted vanadium-doped nickel hydroxide nanostructures for supercapacitor applications

Diffusion and capacitive controlled surfactant assisted vanadium-doped nickel hydroxide nanostructures for supercapacitor applications

Sequential oxygen evolution and decoupled water splitting via electrochemical redox reaction of nickel hydroxides

Alkaline water electrolysis is a promising low-cost strategy for clean and sustainable hydrogen production but is largely limited by the sluggish anodic oxygen evolution reaction and the challenges in maintaining adequate separation between H2 and O2. Here, we reveal an anodic-cathodic sequential oxygen evolution process via electrochemical oxidation and subsequent reduction of Ni hydroxides, enabling much lower overpotentials than conventional anodic oxygen evolution. By using (isotope-labeled) differential electrochemical mass spectrometry and in situ Raman spectroscopy combined with density functional theory calculations, we evidence that the sequential oxygen evolution originates from the electrochemical oxidation of Ni hydroxides to NiOO– active species while undergoing a different, reductive step of NiOO– for the final release of O2 due to weakened Ni–O covalency. Based on this sequential process, we propose and demonstrate a hybrid water electrolysis and energy storage device, which enables time-decoupled hydrogen and oxygen evolution and electrochemical energy storage in the Ni hydroxides.

Synergistic coupling of NiCo-LDH in high-performance supercapacitors via hydrothermal method: Optimal utilization of the potential window

Enhancing the efficiency of layered nickel-cobalt double hydroxides (NiCo-LDH) as electrode materials represented a promising strategy for advancing supercapacitor technology and improving energy storage systems. However, achieving optimal synthesis conditions and addressing the inherent limitations of NiCo-LDH remained critical challenges. In this study, we developed a novel hydrothermal approach to fabricate ultrathin NiCo-LDH nanosheets with a highly porous architecture. In the present study, we have introduced a hydrothermal methodology aimed at the fabrication of ultrathin NiCo-LDH nanosheets characterized by an intricate and highly porous architecture. This innovative approach entailed the simultaneous deposition of nickel and cobalt hydroxides in the presence of ammonium fluoride, a technique that not only streamlined the synthesis process, but also markedly augmented the electrochemical performance of the resultant material. These effects collectively contributed to improved electron transport and structural stability. The optimized NiCo-LDH-18 electrode achieved an exceptional specific capacitance of 2266.6 F g⁻1 and an energy density of 104.8 W h kg⁻1, with a remarkable 93.19 % capacitance retention after 40,000 cycles. Additionally, the potential window of the system closely approximated its theoretical maximum, reaching 96.88 % at a current density of 10 A g⁻1. This refined synthesis strategy offered a significant advancement in supercapacitor performance and stability. By overcoming the inherent drawbacks of traditional supercapacitors, the developed materials provided an effective solution for meeting the growing demand for storage devices with high energy density.

Kinetic Understanding of Metal Ions Doping in Enhancing the Electrocatalytic Ethanol Oxidation Performance of Nickel Hydroxides

Kinetic Understanding of Metal Ions Doping in Enhancing the Electrocatalytic Ethanol Oxidation Performance of Nickel Hydroxides

Revealing Enhanced Active Oxygen Formation by Incorporating Chromium into Nickel Hydroxide Nanosheets for Improved Oxygen Evolution Reaction.

Nickel-based oxyhydroxides have emerged as promising catalysts for the oxygen evolution reaction (OER) among Earth-abundant metals. While the incorporation of foreign elements is recognized to enhance catalytic activity, the origin of this enhancement is still debated. We synthesize and examine Ni hydroxide nanosheets, both with and without Cr doping, to elucidate the underlying enhancements. Operando UV-vis and Raman spectroscopy are employed to unravel the behavior of the catalysts. The Cr doping facilitates the oxidation of Ni, resulting in the generation of active oxygen species. The enriched active oxygen species improves OER performance through a lattice oxygen-mediated pathway in Fe-free KOH, and further contribute to the creation and increased activity of FeOxHy sites in the presence of Fe impurities. This work provides a mechanistic understanding of the performance enhancement in Ni-based catalysts through Cr doping and suggests a strategy for the design of more efficient catalysts in the future.

Microwave-assisted hydrothermal synthesis of αβ-Ni(OH)2 nanoflowers on nickel foam for ultra-stable electrodes of supercapacitors

Transition metal hydroxides (TMHs) are considered promising materials for supercapacitors because of their high theoretical capacitance and tunable morphology. Among TMHs, nickel hydroxide stands out for its multiple oxidation states, facilitating charge storage. This paper reports on a novel microwave-assisted hydrothermal technique employed to synthesize mixed-phase nickel hydroxide nanoflowers directly at the surface of nickel foam substrates with improved electrochemical stability compared to pure phases of nickel hydroxide. The analysis of nickel hydroxide in different phases alpha, beta and mixed-phase materials using physiochemical techniques like XRD, SEM, EDX, RAMAN, FT-IR and TGA is explained. The areal capacitance calculated from GCD tests for α-Ni(OH)2, β-Ni(OH)2 and αβ-Ni(OH)2 is estimated 7.35 F/cm2, 2.66 F/cm2 and 5.12 F/cm2 at a current density of 10 mAcm−2. The mass-specific capacitance calculated from GCD tests for α-Ni(OH)2, β-Ni(OH)2 and αβ-Ni(OH)2 is estimated 2311 Fg−1, 688 Fg−1 and 1511 Fg−1 at a current density of 10 mAcm−2. The cyclic stability test revealed the superior cycling performance of nickel hydroxide in mixed-phase as the cathode of an ultralong supercapacitor with nearly 100% capacitance retention after 5000 cycles at 50 mAcm−2. The proposed synthesis technique advances the efficiency and control of nanostructure geometry, providing insights into the design for electrodes of extreme-performance supercapacitors. However, conventional synthesis methods are time-consuming and energy-intensive. These findings underscore the potential of mixed-phase nickel hydroxide as an outstanding electrode material with extended cyclic performance for supercapacitors, contributing to the improvement of energy storage technologies in the renewable energy landscape.

Comparative studies of cobalt hydroxide and nickel hydroxide designed using novel metal tetrafluoroborate as active materials of battery supercapacitor hybrids

Structure directing agent (SDA) can tailor morphology of active materials with preferable surface properties. Ammonium fluoroborate has been proposed as an effective SDA to synthesize metal organic framework (MOF) derivatives in previous reports, where fluoroborate ions play as morphology regulators by providing steric hindrance. Nickel and cobalt hydroxides are intensively used as active materials in battery supercapacitor hybrids (BSHs), owing to high theoretical capacitances and durability. However, previous studies rarely investigate metal specie effects on energy storage and compare electrochemical performance of nickel and cobalt hydroxides particularly in unique synthesis environments. In this study, nickel tetrafluoroborate (Ni(BF4)2) and cobalt tetrafluoroborate (Co(BF4)2) are respectively used as nickel and cobalt sources to synthesize hydroxides as active materials of BSHs. Tetrafluoroborate ions act as SDAs to design favorable morphologies, while 2-methylimidazole is incorporated to control the pH value for facilitating precipitations. The Ni(OH)2 and Co(OH)2 electrodes respectively show specific capacitances (CF) of 1118.5 and 334.3 F/g at 20 mV/s, owing to the preferable alpha-type hydroxide and larger pore volume/width for Ni(OH)2. A BSH consisted of a Ni(OH)2 positive electrode shows a maximum energy density of 64.0 Wh/kg at 700.0 W/kg, and the CF retention of 116 % and Coulombic efficiency of 94 % after 5000 cycles.

Preparation of Ni-Cu-C composite catalysts prepared from mixed nickel and copper hydroxides for selective hydrogenation of 4-nitrophenol

A high-performance Ni-Cu-C composite catalyst was prepared from mixed nickel hydroxide and copper hydroxide, which were obtained by coprecipitation, by thermal treatment with acetylene-containing gas at 120 °C followed by hydrogen reduction at 180 °C. The characterization results of XRD, TEM, XPS, and H2-TPR measurements confirmed the presence of nickel carbide (Ni3C), copper carbide (CuxC), Cu, and Ni in the matrix of amorphous carbon in the composite catalyst. The mild preparation temperature and the porous carbon shell layers prevented the nano-sized particles from aggregation. The formation of interstitial Ni3C and CuxC significantly enhanced the dissociation of molecular hydrogen, accelerating the selective hydrogenation of 4-nitrophenol (4-NP) to yield 4-aminophenol (4-AP) at relatively mild conditions (80 °C and 1.0 MPa hydrogen pressure). The catalytic performance of the composite catalysts depended strongly on the Ni/Cu molar ratio, with an optimal Ni/Cu molar ratio of 4. In addition, the composite catalyst showed high conversion and selectivity to the corresponding aniline in the selective hydrogenation of other nitroarenes, including nitrobenzene, 4-nitrotoluene, 4-nitrochlorobenzene, 4-nitrobenzaldehyde, 4-nitroacetophenone, and 2-nitroaniline. The catalyst offers a novel approach to rational design and preparation of high-performance abundant metal catalysts for selective hydrogenation of nitroarenes.

The Multifaceted Role of Boric Acid in Nickel Electrodeposition and Electroforming

This study involved an investigation of the role of boric acid in nickel electroforming from sulfamate electrolytes, especially in relation to its ability to minimise interfacial pH changes during electrodeposition. Initial speciation calculations indicated that buffering by polyborate species and nickel-borate complexes are most likely responsible for this effect. However, the concentration of nickel-borate complexes was too low even at elevated pH to be a significant electroactive species. Polarisation and electrochemical quartz crystal microbalance measurements indicated that, in the absence of boric acid, electrodeposits typically contained Ni(OH)2, while boric acid additions resulted in pure Ni being deposited with a current efficiency approaching unity. Boric acid additions substantially modified the nickel and hydrogen partial currents, and influenced the overall current efficiency. Studies in nickel-free solutions indicated that boric acid adsorbs on the surface which explains the suppression of H2O reduction observed in the electroforming experiments. Collectively, solution buffering due to polyborate and nickel-borate species and inhibition of H2O reduction by adsorbed boric acid minimised interfacial pH changes and prevented the formation of nickel hydroxide.

Advances in Nickel Hydroxide: Structures and Modern Applications (review)

This review article provides an overview of research conducted over the past few decades on nickel hydroxide, a crucial material in both physics and chemistry with notable engineering applications, particularly in batteries. It begins by outlining the structures of the two known polymorphs, α-Ni(OH)2 and β-Ni(OH)2. The article also explores various types of disorder commonly found in nickel hydroxide, such as hydration, stacking faults, mechanical stresses, and the incorporation of ionic impurities. Related materials, including intercalated α-derivatives and basic nickel salts, are also discussed. The review goes on to summarize several methods for synthesizing nickel hydroxide, such as chemical and electrochemical precipitation, sol–gel synthesis, chemical aging, hydrothermal and solvothermal synthesis, electrochemical oxidation, microwave-assisted synthesis, and sonochemical methods. Finally, the known physical properties of nickel hydroxide—magnetic, vibrational, optical, electrical, and mechanical—are examined. The concluding section offers a summary of the potentially valuable properties of these materials and techniques for identifying and characterizing unknown nickel hydroxide-based samples.

Synthesis of Ni(OH)2‐g‐C3N4/C Composite by Biological Template for Asymmetric Supercapacitor

Nickel hydroxide (Ni(OH)2) is recognized as a promising material for electrodes in supercapacitors owing to its exceptional theoretical specific capacitance. However, Ni(OH)2 has several drawbacks, including a short cycle life, susceptibility to volume expansion, and poor electrical conductivity. In this work, Ni(OH)2 nanosheets anchored on layered g‐C3N4/C (Ni(OH)2–g–C3N4/C) are designed by biological template induction and a hydrothermal method. Ni(OH)2–g–C3N4/C has unique petal‐like structures, which can provide a vertical charge transport channel to increase reaction potential of the material during the charge–discharge process. The introduction of biomass carbon can solve the problem of the bulk phase accumulation of g‐C3N4 and can also improve the overall conductivity of the composite. Compared to Ni(OH)2 (522 F g−1), g‐C3N4/C (76.2 F g−1), and g‐C3N4 (16 F g−1), the Ni(OH)2–g–C3N4/C‐0.75 (NGC‐0.75) composite exhibits the highest specific capacitance of 1034 F g−1 at 1 A g−1. Furthermore, after 5000 cycles at 5 A g−1, the capacitance of the material is maintained at 85.97%. Meanwhile, the asymmetric supercapacitor based on the NGC‐0.75 shows a high energy density of 18.29 Wh kg−1 at the power density of 400.02 W kg−1 with excellent cyclic stability of 127.45% over 10 000 cycles.

Soft chemistry-derived Al-substituted hydrated nickel hydroxide electrodes for rechargeable aqueous batteries.

Hydrated nickel hydroxides with partial aluminum substitution were synthesized using the conventional coprecipitation and soft chemistry methods. The soft chemistry derived sample showed better reversibility owing to the low activity for oxygen evolution during charging. Operando X-ray diffraction indicated the increased interlayer distance and decreased crystallinity during discharging caused by water accommodation.