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The ca. 3.0 Ga Ni sulfide mineralisation at Maniitsoq, SW Greenland, is hosted by a cluster of relatively small, irregularly shaped mafic-ultramafic intrusions, typically 10s of m to a few km across, that are lodged within broadly coeval gneiss. Many of the intrusions are fault bounded and fragmented so that their original sizes remain unknown. The sulfides form disseminations and sulfide matrix breccia veins displaying sharp contacts to the host intrusives. The mineralisation has relatively high Ni/Cu, with 4–10% Ni and 1–2% Cu. Correlations between Ni and Cu with sulfide content are strong, consistent with a magmatic origin of the mineralisation. PGE contents are mostly below 0.5 ppm, and Cu/Pd is typically above primitive mantle levels, interpreted to reflect equilibration of the parent magma with segregating sulfide melt prior to final magma emplacement. Sulfide segregation was likely triggered by assimilation of crustal sulfur, as suggested by whole rock S/Se ratios of 7000–9000. The sulfide melt underwent extensive fractionation after final emplacement, caused by downward percolation of Cu-rich sulfide melt through incompletely solidified cumulates. We suggest that the exposed Maniitsoq intrusions represent the Ni-rich upper portions of magma conduits implying that there is potential for Cu-rich sulfides in unexposed deeper portions of the belt. [ABSTRACT FROM AUTHOR]

The highly active electrocatalysts are important to promote the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The composition of the material plays important role on the electrocatalytic activity. The nanosheet-like NiFe-MOF-74 is used as precursor to obtain crystalline Fe 0 · 4 Ni 0 · 6 Se 2 (FNS@CC), then Fe 0 · 4 Ni 0 · 6 Se 2 is treated by sulfuration reaction to gain a-FNS@CC composed of crystalline Fe 0 · 4 Ni 0 · 6 Se 2 and amorphous NiS 2 heterostructure. Importantly, by altering the reactive sequence, the Fe 3 Se 4 /NiSeS@CC catalyst comprised of Fe 3 Se 4 and NiSeS crystals is constructed. It is found that the crystal phase, morphology and electronic structure of electrocatalysts are different by tuning the sequence of the reaction. After introducing the amorphous NiS 2 into the crystalline Fe 0 · 4 Ni 0 · 6 Se 2 , the valence of Ni is increased and the R ct value is reduced. Thus, the overpotentials at 10 mA cm−2 for OER/HER of a-FNS@CC are 197 and 100 mV in 1 M KOH, respectively. In addition, the a-FNS@CC displays neglectable current degradation after 120 h I-t test. The a-FNS@CC‖a-FNS@CC overall water splitting system requires only 1.46 V to drive 10 mA cm−2. We provide a novel kind of heterostructure catalyst comprised of crystalline Fe 0 · 4 Ni 0 · 6 Se 2 and amorphous NiS 2. • The composition of the catalyst is tuned by altering the sequence of reaction. • The heterostructure of crystalline Fe 0 · 4 Ni 0 · 6 Se 2 and amorphous NiS 2 was prepared. • The heterostructure with different composition shows different electron state of elements. • With heterostructure catalyst, the EWS only proceeds at 1.46 V to obtain 10 mA cm−2. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting provides a sustainable method for hydrogen production. However, the primary challenge for electrochemical hydrogen generation is the high cost and limited availability of platinum-based noble-metal catalysts. Transition-metal chalcogenides have been identified as low-cost and efficient electrocatalysts to promote the hydrogen evolution reaction (HER) in alkaline electrolytes. Nonetheless, the identification of active sites and the underlying catalytic mechanism remain elusive. In this study, phosphorus-doped nickel sulfide has been successfully synthesized, demonstrating enhanced activity for alkaline HER. Investigating surface chemistry through X-ray photoelectron spectroscopy (XPS), depth profiling revealed that surface restructuring occurs during the HER process. The presence of phosphorus significantly influences this transformation, promoting the formation of a novel active Ni-O layer. This Ni-O layer is responsible for enhanced catalytic activity by upshifting the d-band center and increasing the density of states near the Fermi level, along with expanding the electrochemical surface area. This study reveals that the surface restructuring of transition-metal sulfides is highly tied to the electronic structure of the parent catalysts. Gaining a comprehensive understanding of this surface restructuring is essential for predicting and exploring more efficient non-precious transition-metal sulfide electrocatalysts. [ABSTRACT FROM AUTHOR]

MoS 2 /Ni 3 S 2 interfacial heterojunction is constructed and exhibits superior activity of promoting oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) towards efficient electrocatalytic water splitting process. [Display omitted] In the ongoing quest for cost-effective and durable electrocatalysts for hydrogen production—a critical element of sustainable energy transformation—the 1T phase of Molybdenum Disulfide (MoS 2) faces challenges due to its thermodynamic instability and the trade-off between efficiency and durability. Conversely, the 2H phase of MoS 2 , often disregarded in favor of the metallic 1T phase, suffers from its inert nature and limited active sites. To overcome these limitations, this study employs a straightforward hydrothermal synthesis strategy that couples both 1T and 2H phases of MoS 2 with Ni 3 S 2 , forming 1T- and 2H- MoS 2 /Ni 3 S 2 heterojunctions. Enhanced by Ni 3 S 2 ′s abundant active sites, improved electron transport capabilities, synergistic interface effects, and better structural stability, these heterojunctions achieve a high current density exceeding 500 mA cm−2 at low overpotentials, along with prolonged durability for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolytes. Remarkably, an electrolyzer assembly utilizing 1T-MoS 2 /Ni 3 S 2 as the cathode and 2H-MoS 2 /Ni 3 S 2 as the anode demonstrates a competitive voltage of 1.58 V at 20 mA cm−2, showcasing superior performance in overall water splitting compared to other non-noble metal-based electrocatalysts. This study not only offers a viable method for synthesizing efficient and stable electrocatalysts for water splitting using transition metal-based heterogeneous structures but also addresses the fundamental challenges associated with 1T and 2H phases of MoS 2. [ABSTRACT FROM AUTHOR]

Constructing fast electron transfer pathways and abundant electro-active sites is an effective strategy to improve the oxygen evolution reaction (OER) performance of catalysts. Herein, structural engineering and dual-phase engineering were employed to construct a NiS2 nanoparticle-encapsulated MOF configured with a pseudo-neuronal structure (NiS2/MOF/HT). It was found that the pseudo-neuronal structure, constructed with a carbon nanohorn (CNH) and carbon nanotube (CNT), provided fast electron transfer pathways and abundant exposed active sites. Moreover, the NiS2/MOF/HT composite obtained via partial vulcanization not only inherited the pseudo-neuronal structure but also prevented the aggregation and growth of NiS2 particles. NiS2/MOF composites provide various active sites. With the combination of the promotion of electronic transfer and enrichment of electro-active sites (NiS2, MOF), NiS2/MOF/HT showed excellent performance, whose overpotential at 25 mA cm−2 was reduced by 19.5% compared with MOF/HT. [ABSTRACT FROM AUTHOR]

Inevitable leaching and corrosion under anodic oxidative environment greatly restrict the lifespan of most catalysts with excellent primitive activity for oxygen production. Here, based on Fick' s Law, we present a surface cladding strategy to mitigate Ni dissolution and stabilize lattice oxygen triggering by directional flow of interfacial electrons and strong electronic interactions via constructing elaborately cladding‐type NiO/NiS heterostructure with controlled surface thickness. Multiple in situ characterization technologies indicated that this strategy can effectively prevent the irreversible Ni ions leaching and inhibit lattice oxygen from participating in anodic reaction. Combined with density functional theory calculations, we reveal that the stable interfacial O−Ni−S arrangement can facilitate the accumulation of electrons on surficial NiO side and weaken its Ni−O covalency. This would suppress the overoxidation of Ni and simultaneously fixing the lattice oxygen, thus enabling catalysts with boosted corrosion resistance without sacrificing its activity. Consequently, this cladding‐type NiO/NiS heterostructure exhibits excellent performance with a low overpotential of 256 mV after 500 h. Based on Fick's law, this work demonstrates the positive effect of surface modification through precisely adjusting of the oxygen‐sulfur exchange process, which has paved an innovative and effective way to solve the instability problem of anodic oxidation. [ABSTRACT FROM AUTHOR]

Healthcare diagnostics and supplementary experimental research require electrochemical tools that are straightforward, inexpensive, delicate, quick, and precise. In addition to the previous reports of paracetamol sensors, we present an electrochemical sensor that customs differential pulse voltammetry (DPV) and cyclic voltammetry (CV) to determine the presence of nickel sulfide (NiS) on graphene oxide sheets (GO) (NiS@GO). Utilizing analytical methods, the composite surface morphology and structural characteristics were described. A substantial drop in overpotential was seen in the electrochemical investigation of the NiS@GO composite revised glassy carbon electrode (NiS@GO/GCE) owing to its substantial external part and high hauler agility, which demonstrated remarkable activity towards the oxidation of paracetamol (Para). Para electrochemical sensing was made more accessible by a diffusion-controlled oxidation process with an identical quantity of protons and electrons. From 3.3 µM to 125 µM the concentration of Para ornament linearly with the peak currents during the determination process 0.052 µM was the Para detection limit (3σ/S) sensitivity of the fabricated electrode was 12.14 µA µM−1. In addition, the sensors demonstrated remarkable recovery with actual tablet samples over a month-long period with very little interference from common species. Commercial tablet samples demonstrate a noteworthy potential for wide-ranging applications in the electrochemical sector, with an acceptable recovery rate of 96.6 to 100.8%. An upfront, affordable quality monitoring system that can track the amount of para in tablets may be developed with the help of the suggested electrochemical sensor. Application investigations using the proposed sensor successfully detected Para in drug tabulations and biological materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Fe,Mo-NiS/Ni 9 S 8 /NF catalyst with rich interfaces was prepared from POMs-MOFs. • The rich interfaces within the Fe,Mo-NiS/Ni 9 S 8 /NF catalyst effectively enhanced oxygen evolution reaction. • The Fe,Mo-NiS/Ni 9 S 8 /NF showed desired performance in alkaline sea water electrolysis. Designing a highly coupled interfacial-engineered transition metal sulfide electrocatalyst with rich interfaces is crucial for accelerating the catalytic oxygen evolution reaction (OER), which involves several intermediates. This study presents a novel polyoxometalate-based metal–organic framework (POM-MOF)-derived Fe- and Mo-codoped NiS/Ni 9 S 8 heterostructure supported on a nickel foam (NF) (denoted as Fe,Mo-NiS/Ni 9 S 8 /NF). The newly prepared Fe,Mo-NiS/Ni 9 S 8 /NF catalyst possesses rich interfaces of NiS and Ni 9 S 8 with uniformly doped Fe and Mo atoms. The optimized Fe,Mo-NiS/Ni 9 S 8 /NF catalyst demonstrated best OER performance with ultralow overpotentials of 47 and 56 mV at 10 mA·cm−2 for alkaline and simulated seawater, respectively. This resulting performance is attributed to its low interfacial resistance, fully exposed active sites, superhydrophilic properties, and excellent electronic interactions. Furthermore, Fe,Mo-NiS/Ni 9 S 8 /NF exhibited strong durability under both alkaline and simulated seawater conditions for 100 h, fulfilling the requirements of an effective water oxidation electrocatalyst. This study focused on the design and optimization of POM-MOF sulfide derivatives for electrocatalytic OER, offering broadened avenues for the application of POM-MOF-derived heterostructures in renewable energy conversion and storage. [ABSTRACT FROM AUTHOR]

Nickel sulphide (NiS) with its low band gap and interesting optical properties, is able to absorb visible light, thus possess appreciable photocatalytic properties. However, their synthesis by green and sustainable methods with controlled morphologies, sizes and phases for specific applications remains a major challenge. We herein report the green synthesis of olive oil- (OO) and castor oil-(CO) capped NixSy nanoparticles by the thermolysis of [Ni(L)2] (1) and [Ni2(L)3(SCN)].6H2O (2) complexes as single source precursors (SSPs) at 190 °C and 230 °C, (L being furan-2-carbaldehyde thiosemicarbazone). The single crystal X-ray structure of compound (1) has been elucidated. The influence of reaction parameters on the structure, morphology, size, optical and photocatalytic properties of the synthesized nanoparticles Has been examined using various techniques. Results of powder X-ray diffraction (p-XRD) reveal a mixture of hexagonal Ni17S18 and orthorhombic Ni9S8 nanomaterials. Energy dispersive X-ray spectroscopy (EDX) confirmed the elemental composition of NixSy nanoparticles. Transmission electron microscopy (TEM) images revealed spherical and fibrous nanoparticles with sizes ranging between 3.0 and 25.3 nm. Optical properties of NixSy nanoparticles. The band gap energies obtained from Tauc plots vary between 2.25 and 2.49 eV and 2.29–2.50 eV for NixSy nanoparticles derived from complex (1) and complex (2) respectively and show considerable blue shift from its bulk value due to quantum size confinement effect. The presence of peaks around 1390 and 1561 cm-1 in the Raman spectra confirm the formation of olive and castor oil capped nickel sulphide nanoparticles (NPs). These results suggest that crystallinity, size, morphology and optical properties of the synthesized NixSy NPs were affected by thermolysis temperature, capping agent and precursor type. The as-prepared nickel sulphide nanoparticles were used as photocatalysts for the degradation of methylene blue (MB) at a concentration of 10 ppm under UV light irradiation. Nickel sulphide nanoparticles obtained in olive oil at 190 °C using complex (2) as SSP, showed a maximum degradation efficiency of 52.0% after 180 min, suggesting that NixSy nanoparticles can be used as photocatalysts for the degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

Developing low‐cost and highly efficient electrocatalysts toward oxygen evolution reaction (OER) is of vital significance for electrochemical water splitting. Herein, we fabricate a heterostructure NiS/Ni(OH)x electrocatalyst (Ni‐S‐n) with regenerative oxygen vacancies via electro‐deposition on nickel foam (NF) followed by a facile NaBH4 reduction. The resulting Ni‐S‐5 catalyst with appropriate amount of oxygen vacancies (Ovs) exhibits extraordinary activity for alkaline OER with overpotential of 142 mV and 248 mV to reach the current density of 10 mA cm−2 and 100 mA cm−2, respectively. This catalyst also shows remarkable durability with 40 h. After the stability test, the excellent OER performance is well recovered by regenerating the surface oxygen vacancies (Ovs) significantly with additional NaBH4 reduction. The Ni‐S‐5 catalyst still displays good activity even after repeating it three times (180 h). The surface oxygen vacancies act as vital active sites for OER. A mechanism of Ovs species transformation and regeneration based on the Ni‐S‐5 catalyst is proposed, which provides a new direction for exploring ultrastable and efficient OER electrocatalysts with renewable active species. [ABSTRACT FROM AUTHOR]

Among efficient electrocatalysts used for hydrogen evolution reaction (HER) from electrocatalytic water splitting, the nickel-based sulfides exhibit promising applications via effective heteroatom doping strategy. Herein, we deeply investigate the fundamental mechanism of the Cu doping towards the HER performance improvement of NiS 2 catalyst. Firstly, based on the density functional theory calculations, the Cu doping can efficiently modulate the electronic structure of NiS 2 , thereby optimizing the adsorption free energies of hydrogen and H 2 O, and enhancing the kinetics of H 2 O dissociation. Secondly, we prepare the Cu-doped NiS 2 nanosheet arrays on carbon fiber paper (Cu–NiS 2 /CFP), exhibiting superior alkaline HER performances compared with NiS 2 nanosheet arrays on CFP (NiS 2 /CFP). Specifically, Cu–NiS 2 /CFP shows a low HER overpotential of 75 mV at the cathodic current density of 10 mA/cm2 in 1 M KOH. Both aspects of theory calculations and experiments together certify the Cu doping can efficiently modulate NiS 2 catalyst to improve alkaline HER performances. • Efficient modulation of NiS 2 electrocatalyst via the Cu doping strategy. • Optimized adsorption free energies of H∗ and H 2 O∗ on NiS 2 benefitted from Cu doping. • Enhanced kinetics of H 2 O dissociation process on NiS 2 benefitted from Cu doping. • Optimized electronic structure of NiS 2 catalyst benefitted from Cu doping. • Improved hydrogen evolution reaction performances of NiS 2 attributed to Cu doping. [ABSTRACT FROM AUTHOR]

There is a growing interest in the development of active, durable, and cost-effective electrocatalysts for oxygen evolution reactions (OER). In this study, we synthesized a self-reconstruction iron-doped sulfide-regulated nickel molybdate catalyst using wet chemical sulfuration and electrodeposition techniques. The core-shell nanorods (SC@NMO) were produced through rapid sulfuration. We investigated the effects of sulfur leaching on rapid and extensive electrochemical self-reconstruction. Our approach utilized the phase change of Fe3+ and electrodeposition-induced restructuring to enhance the catalyst's OER activity and stability in an alkaline electrolyte. Notably, iron ions establish a precipitation-dissolution dynamic equilibrium at the interface between the catalyst surface and the electrolyte, which minimizes iron loss and results in a more efficient and stable catalyst. The prepared sample, SC-Fe(Ni)OOH@NMO, demonstrated exceptional oxygen evolution performance and long-term stability in a 1 M KOH solution, achieving an overpotential of only 279 mV at a current density of 100 mA cm−2. It maintained stable operation for 200 h in a high-concentration 6 M KOH solution. The above data prove that this work provides a feasible strategy to enhance the OER catalytic capacity of metal oxides by the two modification methods of co-doping of metal and non-metal and reconstruction. [Display omitted] • The core-shell nanorods were obtained by wet sulfuration. • The dynamic reconstruction of Fe3+ improves the catalyst's activity and stability. • SC-NiFeOOH@NMO has long-term stability in high concentration alkaline medium. [ABSTRACT FROM AUTHOR]

Nickel and cobalt sulfide-based catalysts supported on a silicon-pillared MFI zeolite were synthesized, characterized, and tested in the hydrodesulfurization reaction of dibenzothiophene. The metallic phases were incorporated by following the incipient wetness impregnation process, and different techniques were employed to determine the physicochemical properties of the obtained catalysts, such as X-ray diffraction, N2 adsorption–desorption at – 196 °C, Infrared Spectroscopy and High-Resolution Transmission Electron Microscopy. The catalytic performance in the hydrodesulfurization of dibenzothiophene showed that the NiW catalyst was the most active due to the redispersion of NiS on WS2 to form the active NiWS phase. Instead, the desired CoWS phase did not occur under the presence of cobalt, and therefore, the catalytic performance worsened. [ABSTRACT FROM AUTHOR]

Products from the thermal conversion of heavy crude oil in the presence of Ni- and Co-containing catalysts formed in situ from a mixture of appropriate salts with ethanol have been studied. In the catalytic process, the light fraction yield increases from 51 to 63% and the coke yield decreases from 3 to 2 wt % compared with the respective parameters of thermal cracking. In the case of a mixed Ni+Co catalyst, the lowest yields of gas (5 wt %) and coke (0.1 wt %) are observed. The decrease in sulfur content in both the thermal cracking (by 17%) and catalytic cracking products (by 12–32 rel %) occurs primarily due to the removal of sulfur in the form of gaseous products. The structural group characteristics of average asphaltene molecules before and after heavy crude oil cracking have been studied. Using X-ray diffraction analysis, Ni0.96S, Ni9S8, and Co9S8 phases have been identified in the solid cracking products. [ABSTRACT FROM AUTHOR]

Nickel oxide (NiO), nickel hydroxide (Ni(OH)2), and nickel sulfide (NiS) nanoparticles have been fabricated using a simple co-precipitation method. The effect of different structures and morphologies of the prepared nanoparticles on a supercapacitor have been investigated. The prepared nanoparticles were characterized by UV, XRD, FESEM, and EDAX. The XRD demonstrated face centered cubic (FCC), hexagonal, and rhombohedral molecular structures of the nanoparticles. The FESEM analysis found a non-uniform aggregated spherical morphology of NiO, a rock-like morphology of Ni(OH)2, and an irregular spherical morphology of NiS. In KOH electrolyte, NiO stainless-steel electrodes showed a better performance, exhibiting a high specific capacitance of 438 F/g with a good cycling stability of 87% after 1000 cycles. NiO has the lowest conducting resistance among the three nanoparticles, was effectively optimized as a superior electrode, and yielded the greatest pseudo-capacitance by carbon-free electrode fabrication. This study suggests simple ways to enhance a supercapacitor's electrochemical characteristics. [ABSTRACT FROM AUTHOR]

Anion exchange membrane (AEM) water electrolysers have shown their potential in green hydrogen production. One of the crucial tasks is to discover novel cost‐effective and sustainable electrocatalyst materials. In this study, a low‐cost Ni−S‐based catalyst for hydrogen evolution reaction was prepared via a simple electrodeposition process from a modified Watts bath recipe. Physical characterisation methods suggest this deposit film to be amorphous. Optimisation of the electrodeposition parameters of the NixSy catalyst was carried out using a rotating disk electrode setup. The optimised catalyst exhibited excellent catalytical performance in 1 M KOH on a microelectrode, with overpotentials of 41 mV, 111 mV and 202 mV at 10, 100 and 1000 mA cm−2 with Tafel slope of 67.9 mV dec−1 recorded at 333 K. Long‐term testing of the catalyst demonstrated steady performance over a 24 h period on microelectrode at 100 mA cm−2 with only 71 mV and 37 mV overpotential increase at 293 K and 333 K respectively. Full cell testing with the optimised NixSy as cathode and NiFe(OH)2 as anode showed 1.88 V after 1 h electrolysis at 500 mA cm−2 in 1 M KOH under 333 K with FAA‐3‐30 membrane. [ABSTRACT FROM AUTHOR]

Self-supported NiCo 2 O 4 @Ni 1.18 S core-shell nanocomposite were synthesized on nickel foams by uniform growth Ni 1.18 S nanosheets encircling NiCo 2 O 4 nanoneedles. Characterization results demonstrate that NiCo 2 O 4 @Ni 1.18 S core-shell nanocomposite have significant advantages in one - and two-dimensional nanostructure coordination structure, with richer REDOX active sites and more energy storage paths. Density functional theory (DFT) calculations results indicate that the surficial adsorption energy with OH− ions is enhanced in NiCo 2 O 4 @ Ni 1.18 S nanocomposite, thereby facilitating the reversible redox reaction kinetics and the electrochemical activity. As a result, self-supported NiCo 2 O 4 @Ni 1.18 S core-shell nanocomposite exhibit excellent energy-storage properties, i.e.: the specific charge capacity of 3158 F g−1 at 1 A g−1, high rate performance of 52.3 % from 1 A g−1 to 5 A g−1, and the 81.25 % capacity retention rate after 5000 cycles. Especially, it should be pointed out that the hybrid supercapacitors assembled from self-supported NiCo 2 O 4 @Ni 1.18 S core-shell nanocomposite and activated carbon present the wide voltage window (0–1.6 V), high energy density of 100.3 Wh kg−1 at power density of 177 W kg−1 and prospective commercial consideration. These facts fully prove the practical feasibility of self-supported NiCo 2 O 4 @Ni 1.18 S core-shell nanocomposite in advanced energy-storage facilities. [Display omitted] • NiCo 2 O 4 @Ni 1.18 S core-shell nanocomposite are constructed by hydrothermal-calcination-electrodeposition method. • This core-shell nanostructure has the structural advantages and composition complementariness. • Hybrid supercapacitors are assemled based on core-shell NiCo 2 O 4 @Ni 1.18 S and active carbon. • Hybrid device is promising for smart watches, electric vehicles, and wearable electronics, etc. [ABSTRACT FROM AUTHOR]

The catalytic activity of an unsupported nickel-promoted tungsten disulfide catalyst prepared in situ in the reaction medium was studied in the competitive hydrodechlorination of 1,4-dichlorobenzene and hydrodeazotization of quinoline. The morphology and phase composition of the catalyst were studied by x-ray photoelectron spectroscopy and transmission electron microscopy. This study indicated the presence of nickel sulfide, nickel chloride and a mixed NiWS phase on the surface of the tungsten disulfide catalyst. A considerable decrease in catalyst activity was noted during the concurrent hydrodechlorination and hydrodeazotization reactions, leading to a decrease in the extent of hydrodechlorination of 1,4-dichlorobenzene. The loss of catalyst activity was attributed to the strong adsorption of nitrogen-containing compounds as well as the accumulation of quinolinium salts on the catalyst surface. [ABSTRACT FROM AUTHOR]

Nickel sulfide nanoparticles were successfully synthesized through a meticulous process involving a well-mixed powder of Ni(CH3COO)2∙2H2O and Thiourea. The X-ray diffraction analysis provided insights into the structural nature of NiS, revealing its polycrystalline characteristics with a hexagonal system. This information is fundamental, as it forms the basis for understanding the material's behavior and functionality in various applications. Determining the average values of mean crystallite size, microstrain, and dislocation Nickel sulfide nanoparticles were successfully synthesized through a careful process involving a well-mixed powder of Ni(II)2∙2H2O and Thiourea. The X-ray diffraction analysis provided insights into the structural nature of NiS, revealing its polycrystalline characteristics with a hexagonal system. This information is crucial as it forms the basis for understanding the material's behavior and functionality in various applications. Determining the average values of mean crystallite size, microstrain, and dislocation density for the (100) plane (32.62 nm, 0.000296, and 0.000939 nm-2, respectively) contributes to a comprehensive understanding of the material's structural features. The photoluminescence spectrum of NiS in the visible region revealed split peaks at 405.8 and 428.25 nm, shedding light on the radiative recombination process between electrons and holes. The confirmation of thermal stability through a thermogravimetry diagram is essential for applications in elevated temperature environments, ensuring the material's reliability under varying conditions. Analyzing the stoichiometry of NiS using energy dispersive spectroscopy attached to transmission electron microscopy provides insights into the material's composition. Cyclic voltammetry results indicating a diffusion coefficient greater than that of NiS added to carbon hold significance for electrochemical applications. The unique characteristic peaks observed in cyclic voltammetry for fuel cell applications suggest the potential use of NiS in energy conversion technologies, broadening its scope of application. The confirmation of NiS's ability to elucidate the physical and electronic properties of electrochemical systems through electrochemical impedance spectroscopy underlines its importance as a versatile material in various research and practical domains. [ABSTRACT FROM AUTHOR]

Photo-assisted energy storage systems, by which solar energy can be both converted and stored, have been of interest in the past few years. Novel energy conversion and storage technology is offered by photo-supercapacitors through the combination of an energy collecting unit and a supercapacitor. This dual-application system effectively generates and stores power in a single device, which makes it appropriate for various purposes. In this work, the electrochemical anodization-electrodeposition has been employed to fabricate manganese-nickel sulfide (Mn–Ni–S) nanostructures on titania nanotubes (TNs) and used them as photoelectrodes in photo-supercapacitors. The high surface area and improved properties make TNs considerably important for energy production and storage. Photoelectrochemical analysis was carried out in a three-electrode system under a xenon (Xe) lamp irradiation using the film prepared as the photoelectrode. The highest photocurrent and photovoltage were shown by MnNiS-3/TN electrode, indicating its superior photosensitivity. Upon illumination under a 0.7 mA/cm2 current density, the area-specific capacitance of MnNiS-3/TN electrode increased from 388.3 to 723.3 mF/cm2, which is 2.0, 3.6, and 12.8 times higher than the corresponding values for NiS/TN, MnS/TN, and bare TN electrodes under similar conditions, respectively. This indicates the considerable enhancement of the capacitance of this electrode induced by light. The desirable light-sensitive properties of MnNiS/TN make it capable of simultaneous solar energy harvesting and storage. Light sensitivity makes it possible to charge MnNiS/TN optically. More importantly, upon light irradiation, the capacity can be increased from 374.7 to 630.2 mF/cm2 (current density 0.5 mA/cm2) compared to the corresponding value in the dark. Using MnNiS-3/TN as the best photoelectrode and MnS/FTO, NiS/FTO, MnNiS-1/FTO, MnNiS-2/FTO, and MnNiS-3/FTO as the counter electrodes, photo-charged through light illumination on their surfaces, five asymmetric solid-state photo-supercapacitors (ASSPS) were prepared. MnNiS-3/TN//MnNiS-3/FTO device showed the largest CV curve area, which indicated its highest areal capacitance. High capacitance gain under irradiation (155.7% at 2.0 mA/cm2) and outstanding capacitance maintenance (97.9% over 10000 cycles) were shown by this ASSPS. Furthermore, a great energy density of 4855.4 mWh/cm2 was shown by the MnNiS-3/TN//MnNiS-3/FTO device under light irradiation. This research introduces a novel approach to the development of powerful solar energy conversion/storage devices. [Display omitted] • Mn–Ni sulfides with various Mn/Ni ratios have been grown on titania by co-electrodeposition. • The highest photocurrent and photovoltage were shown by MnNiS-3/TN. • Upon illumination, the area-specific capacitance of MnNiS-3/TN electrode increased from 388.3 to 723.3 mF/cm2. • Using MnNiS-3/TN as the best photoelectrode, five asymmetric solid-state photo-supercapacitors (ASSPS) were prepared. • High capacitance gain under irradiation (155.7% at 2.0 mA/cm2) and outstanding capacitance maintenance (97.9% over 10000 cycles) were shown by this ASSPS. [ABSTRACT FROM AUTHOR]

Efficient and cost-effective catalysts for hydrogen evolution reaction (HER) are essential for large-scale hydrogen production, which is a critical step toward reducing carbon emissions and advancing the global transition to sustainable energy. Nickel sulfide-based catalysts, which exist in various stoichiometries, show promise for HER in alkaline media. However, as single-phase materials, they do not demonstrate superior activity compared to Pt-based catalysts. This review highlights recent strategies to enhance the HER performance of nickel sulfides, including heteroatom doping, heterostructure construction, and vacancy engineering, tailored to their different stoichiometric ratios. The study also examines synthesis methods, characterizations, and their impact on HER performance. Furthermore, it discusses the challenges and limitations of current research and suggests future directions for improvement. [ABSTRACT FROM AUTHOR]

Fe and Mo co-doped Ni 3 S 2 nanorod array is in situ built on Ni foam using Keplerate polyoxomolybdate as precursor and performs efficiently for electrocatalytic overall water splitting, capable of achieving a low cell voltage of 1.60 V and Faradaic efficiency of nearly 100%. [Display omitted] • Free-standing Fe and Mo co-doped Ni 3 S 2 nanorod array is in situ built on Ni foam using Keplerate polyoxomolybdate as precursor. • Fe-MoS 2 /Ni 3 S 2 @NF is reported first time for overall water splitting. • Fe and Mo co-doping modulates the electronic structure of Ni 3 S 2 and induces abundant active sites. • Fe-MoS 2 /Ni 3 S 2 @NF attains a more exceptional electrochemistry improvement, faster electron transfer, better reaction kinetics and long-term durability. Heazlewoodite nickel sulfide (Ni 3 S 2) is advocated as a promising nonnoble catalyst for electrochemical water splitting because of its unique structure configuration and high conductivity. However, the low active sites and strong sulfur–hydrogen bonds (S–H ads) formed on Ni 3 S 2 surface greatly inhibit the desorption of H ads and reduce the hydrogen and oxygen evolution reaction (HER and OER) activity. Doping is a valid strategy to stimulate the intrinsic catalytic activity of pristine Ni 3 S 2 via modifying the active site. Herein, the Ni foam supported Fe and Mo co-doped Ni 3 S 2 electrocatalysts (Fe-MoS 2 /Ni 3 S 2 @NF) have been constructed using Keplerate polyoxomolybdate {Mo 72 F 30 } as precursor through a facile hydrothermal process. Experimental results certificate that Fe and Mo co-doping can effectively tune the local electronic structure, facilitate the interfacial electron transfer, and improve the intrinsic activity. Consequently, the Fe-MoS 2 /Ni 3 S 2 @NF display more excellent HER and OER activity than MoS 2 /Ni 3 S 2 @NF and bare Ni 3 S 2 @NF by delivering the 10 and 50 mA cm−2 current densities at ultra-low overpotentials of 74/175 and 80/160 mV for HER and OER. Moreover, when coupled in an alkaline electrolyzer, Fe-MoS 2 /Ni 3 S 2 @NF approached the current of 10 mA cm−2 under a cell voltage of 1.60 V and exhibit excellent stability. The strategy to realize tunable catalytic behaviors via foreign metal doping provides a new avenue to optimize the water splitting catalysts. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Unsymmetric sulfides and selenides have great applications in the pharmaceutical field. Herein, we describe the reductive coupling reaction of xanthate esters with sulfur‐containing and selenium‐containing compounds (thio(seleno)sulfonates and disulfides(selenides)) under the nickel‐catalyzed condition. It provides a mild and effective method for the synthesis of unsymmetric sulfides and selenides which has the advantages of mild reaction conditions, high yields and a wide range of substrates. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. The contents list includes various articles on topics such as halogen bonding in crown ether chemistry, metal-organic framework-derived materials for enhanced performance of aqueous zinc ion batteries, and the effect of grain boundary doping on the mechanical behavior of Ta bicrystal. The journal is published by The Royal Society of Chemistry, a leading chemistry community. [Extracted from the article]

Nickel sulfides prepared using conventional methods usually exhibit bulk structure and multiple phases, which pose great challenges for controllably synthesizing designer particles with high performance. Herein, we developed a novel and universal strategy to regulate the crystal phase and structure of nickel sulfide through an acid- or alkaline-induced strategy. We found that HCl and KOH could partially extract nickel and sulfur from nickel sulfide under a hydrothermal process, respectively. As a result, HCl treatment induced the transformation of nickel sulfide from nickel-rich phase (NiS) to nickel-deficient phase (NiS2) and bulk structure to micro–nano structure. The KOH treatment induced the transformation of nickel sulfide from a sulfur-rich phase (NiS2) to a sulfur-deficient phase (NiS), as well as the changes in surface microstructure. Attributed to the structural advantages brought by structure reconstruction, these samples exhibit enhanced electrochemical properties after the treatment. This is a unique and significant finding to the structure-regulation method of transition metal sulfides and will enrich their structure-dependent applications in supercapacitors or batteries. [ABSTRACT FROM AUTHOR]

A series of physical mixtures of Na4P2S6 and NiCl2 (P‐NiPS(x), where x represents the P/Ni molar ratio) were employed for the preparation of Ni2P. For comparison, a sulfur‐containing Ni2P catalyst (Ni2P‐S) and a sulfur‐free Ni2P catalyst (Ni2P‐TPR) were prepared by reduction of Ni2P2S6 and a nickel phosphate precursor, respectively. The reduction of the P‐NiPS(x) precursors with P/Ni ratios above 2/3 yielded Ni2P catalysts with a distinct nickel phosphosulfide layer (NiPS(x)), and the Ni2P phase started to form at ca. 200 °C. The reduction of Ni2P2S6 to Ni2P most likely follows a disproportionation mechanism. The P3+ species in Ni2P2S6 disproportionate to PH3 and P5+ during the reduction, and PH3 further reacts with nickel and sulfur species to form Ni2P and the surface nickel phosphosulfide layer. The sulfur atoms in the nickel phosphosulfide phase were in the form of S2−. The introduction of sulfur to Ni2P favored the hydrogenation pathway of the hydrodesulfurization (HDS) of dibenzothiophene (DBT), but hardly affected the direct desulfurization (DDS) pathway and inhibited the hydrogenation of biphenyl. The DDS pathway rate constants of DBT HDS over the Ni2P‐TPR and NiPS(x) catalysts were observed to increase linearly with the increase in their surface Ni atomic concentrations. [ABSTRACT FROM AUTHOR]

A series of physical mixtures of Na4P2S6 and NiCl2 (P‐NiPS(x), where x represents the P/Ni molar ratio) were employed for the preparation of Ni2P. For comparison, a sulfur‐containing Ni2P catalyst (Ni2P‐S) and a sulfur‐free Ni2P catalyst (Ni2P‐TPR) were prepared by reduction of Ni2P2S6 and a nickel phosphate precursor, respectively. The reduction of the P‐NiPS(x) precursors with P/Ni ratios above 2/3 yielded Ni2P catalysts with a distinct nickel phosphosulfide layer (NiPS(x)), and the Ni2P phase started to form at ca. 200 °C. The reduction of Ni2P2S6 to Ni2P most likely follows a disproportionation mechanism. The P3+ species in Ni2P2S6 disproportionate to PH3 and P5+ during the reduction, and PH3 further reacts with nickel and sulfur species to form Ni2P and the surface nickel phosphosulfide layer. The sulfur atoms in the nickel phosphosulfide phase were in the form of S2−. The introduction of sulfur to Ni2P favored the hydrogenation pathway of the hydrodesulfurization (HDS) of dibenzothiophene (DBT), but hardly affected the direct desulfurization (DDS) pathway and inhibited the hydrogenation of biphenyl. The DDS pathway rate constants of DBT HDS over the Ni2P‐TPR and NiPS(x) catalysts were observed to increase linearly with the increase in their surface Ni atomic concentrations. [ABSTRACT FROM AUTHOR]

Developing low‐cost and exceedingly efficient electrocatalysts for oxygen evolution reaction (OER) is vital for application of hydrogen production from water splitting. Herein, three different nickel sulfides on nickel foam were fabricated via a simple sulfuring the as‐formed Ni‐MOF with different sulfide as the sulfur source. The effect of sulfur source on OER performance, morphology and structure of the as‐prepared product are well discussed. The optimized Ni‐MOF/NF‐SS deliver overpotentials of 253 and 330 mV to reach current densities of 10 and 100 mA cm−2 with a small Tafel slope of 70.9 mVdec−1, and stability of over 50 h. This work provides insights into the relationship between the OER activity and the structures of nickel sulfides, but also affords a new route to fabricate nickel sulfides‐based electrocatalysts for OER. [ABSTRACT FROM AUTHOR]

A series of Ni3S2 electrocatalysts were successfully prepared using nickel foam precursor as substrate and thiourea, sodium thiosulfate pentahydrate, sodium sulfide nonahydrate and sodium diethyldithiocarbamate as sulfur sources, and their performances in electrocatalytic hydrogen evolution (HER) were further compared. The results exhibited that the Ni3S2 catalyst prepared with sodium thiosulfate pentahydrate as the sulfur source showed the best performance in HER. At a current density of 10 mA cm−2, the overpotential was only 178 mV, and the Tafel slope was 70.4 mV dec−1. In addition, through the double-layer capacitance test, it was found that the catalyst had the highest electrochemical active area, and the capacitance reached 41.33 mF cm−2, which was consistent with its excellent HER performance. In this work, the influence mechanism of different sulfur sources on the sulfurization process of Ni3S2 catalyst and the further impact of these effects on the performance of HER were also discussed in detail. These results provide a solid theoretical and experimental basis for optimizing the application of Ni3S2 catalyst in the field of electrocatalytic hydrogen production. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to determine the order of the paragenetic sequence and phase transitions of the Ni–Fe sulfide association hosted in listvenites. Listvenites are hydrothermally altered mafic and ultramafic rocks that are often associated with active tectonic settings, such as transform faults, suture zones, and regional extensional faults, usually in contact with volcanic or carbonate rocks. Listvenitization is displayed by a carbonation process when the original olivine, pyroxene, and serpentine group minerals are altered to Mg–Fe–Ca carbonates (magnesite, calcite, dolomite, and siderite), talc, quartz, and accessory Cr spinel, fuchsite, and Ni–Fe sulfides. The formed rocks are highly reactive; therefore, very often, younger hydrothermal processes are observed, overprinting the mineralogy and geochemistry of the original listvenitization products, including accessory Ni–Fe sulfide paragenesis. The studied samples of listvenites were collected from two locations in Kosovo (Vardar Zone): Janjevo and Melenica. The Ni–Fe sulfide textures and relationships with the surrounding listvenite-hosted minerals were obtained using reflected and transmitted light microscopy, while their chemical composition was determined using an electron microprobe. They form accessory mono-or polymetallic aggregates that usually do not exceed 100 μm in size disseminated in the studied listvenites. Generally, the paragenetic sequence of Ni–Fe sulfides is divided into three stages. The first pre-listvenite magmatic phase is represented by pentlandite and millerite. The second listvenite stage consists of Ni–Co bearing pyrite I (Ni content up to 11.57 wt.% [0.24 apfu], and Co content up to 6.54 wt.% [0.14 apfu]) and differentiated thiospinels (violarite + siegenite ± polydymite). The last, late listvenite stage is represented by younger gersdorffite−ullmannite and base metal mineralization: pyrite + marcasite + sphalerite + galena ± chalcopyrite ± sulfosalts. The findings obtained should help in the interpretation of many disseminated accessory Ni–Fe–Co mineralizations associated with mafic and ultramafic rocks worldwide. [ABSTRACT FROM AUTHOR]

Nickel is an important raw metal material in industry, which has been identified as a strategic mineral resource by the Chinese Ministry of Land and Resources. Nickel sulfide ore accounts for 40% of all nickel ores worldwide. However, magnesium silicate gangue minerals in sulfide nickel ores, particularly serpentine, pose significant challenges to the flotation of nickel sulfide ores. The presence of magnesium silicate gangue leads to a series of issues, including increased energy consumption in subsequent smelting processes, accelerated equipment wastage, and increased SO2 emissions, which severely impact the comprehensive utilization of nickel resources in sulfide nickel ores. In this regard, flotation depressants are the most direct and effective method to reduce adverse influences caused by magnesium silicate gangue in the flotation of nickel sulfide ore concentrate. Based on the characteristics of the typical magnesium-containing nickel sulfide ore, this review illustrates the difficulties of the depression of magnesium silicate gangue during the flotation of nickel sulfide ore and gives an overview of the common depressants from six aspects (chelation depressants, dispersion depressants, flocculation depressants, depressants for grinding, depressants for slurry adjustment and combination depressants). Each section summarizes the relevant depression mechanisms and analyzes the advantages and disadvantages of various reagents, providing a reference for designing depressants specifically targeting serpentine. [ABSTRACT FROM AUTHOR]

The inclusion of ruthenium (Ru) to decorate nickel sulphide (Ru@NiS/Ni foam) resulted in a highly efficient electrocatalyst for the alkaline HER by enhancing water dissociation at the interface and reducing the energy barrier of the Volmer step. This strategic fusion significantly boosts the catalyst's performance in facilitating hydrogen production. [ABSTRACT FROM AUTHOR]

Recently, Ni‐based chalcogenides havedemonstrated remarkable activity and selectivity for alcohol electrooxidation, but the mechanisms remain debated. This study synthesizes Ni‐based electrodeswith different chalcogen anion coordination on nickel nanorod arrays (NiOx/Ni,NiSx/Ni, and NiSex/Ni NRAs). NiSex/Ni NRAsshowcases superior performance (Faradaic efficiency 92.9%) in glycerolelectrooxidation reaction (GOR). In situ spectroscopy reveals that NiSecoordination inhibits deep oxidative reconstruction of the Ni‐based interface, preventingNiOOH phase formation during GOR, enhancing activity and stability of NiSex/NiNRAs. Conversely, NiS and NiO coordination lead to deep reconstruction with NiOOHphase formation, limiting GOR performance. Differently, during competingreaction of GOR, the oxygen evolution reaction (OER) leads to deepreconstruction of NiSex interface due to the instability of Ni‐Sebonds, inducing performance degradation and dissolution of Se components. Furthermechanism investigation elucidates that the rate‐determining step (RDS) ofGOR at the NiSex interface involves oxidation of *C2H3O3 intermediatesthrough H2O adsorption, favoring stable formate production.Contrarily, the RDS at the NiSx, NiOx, and NiOOHinterfaces predominantly focus on the decarboxylation of multi‐carbon intermediates, raisingenergy barriers and over‐oxidizing formate to CO2. These results providenew insights for designing Ni‐based non‐oxide catalysts forefficient and stable electrocatalytic oxidation. [ABSTRACT FROM AUTHOR]

Hydrogen is an important energy carrier without carbon emissions. To achieve a carbon‐neutral world, the demand for hydrogen is very significant. In the process of producing green hydrogen, water splitting using electrocatalysts is a desirable process among many methods. The ideal electrocatalyst for hydrogen evolution is the platinum group of metals; however, the limitations of high cost and low abundance hinder large‐scale hydrogen production. Hence, researchers are trying to develop materials from more abundant and less expensive. Hence, in this review, we focus on the fundamental principles of hydrogen evolution reaction (HER) and various synthesis methods and strategies. From the material perspective, we focus on nickel sulfide‐based nanomaterials of different phases during the last four years of development. We compared the electrocatalyst parameters concerning the synthesis methods and strategies chosen. Finally, we have also discussed future challenges. Ultimately, by synthesizing the collective knowledge amassed in the field of HER research, this review endeavors to offer a comprehensive resource for researchers, engineers, and policymakers striving to advance hydrogen‐based energy technologies. In doing so, we aspire to foster continued innovation and collaboration toward realizing a sustainable energy future powered by hydrogen. [ABSTRACT FROM AUTHOR]

Hydrogen is an efficient and environmentally friendly energy source, and the development of cost-effective electrocatalysts is crucial for improving the efficiency of hydrogen production by water electrolysis. Despite the excellent electrolysis efficiency of noble metal catalysts, their cost and reserves have hindered commercial applications, so more attention has been paid to the study of non-precious metal catalysts in recent years. Nickel sulfide phase composites with various structures offer a wide scope for modification engineering of electrocatalysts and are ideal for electrocatalytic materials. In this work, we comprehensively review the research progress of nickel sulfide phase composites, focusing on the synthesis strategies of nickel sulfide composites as well as the four main modifications affecting the performance of electrolytic water: morphology engineering, heterogeneous structures, defect engineering, and substrate materials. It is found that the impact on electrolytic water properties is multiplied by utilizing clever modifications. Finally, the limitations of the current research on nickel sulfide phase electrocatalytic materials are analyzed. [Display omitted] • The special properties of nickel sulfide-based electrocatalytic materials are discussed. • The synthesis strategies of nickel sulfide-based materials were summarized and compared. • The modification strategies of nickel sulfide-based electrocatalysts are analyzed. [ABSTRACT FROM AUTHOR]

The ongoing pursuit of cost-effective approaches for synthesizing transition metal sulfide heterostructure oxygen evolution electrocatalysts, with the objective of optimizing active site exposure and stabilizing spatial framework, remains a significant challenge. In this study, self-supported bimetallic iron-nickel sulfide (Fe 1-x S-NiS/NF) nanosheet heterostructures were successfully fabricated in situ on nickel foam through the direct sulfurization of bimetallic carbonate precursors. The effects of sulfurization temperature and Fe content on the oxygen evolution reaction (OER) performance of the catalyst are investigated, and the best conditions are found to be 350 °C and 2 mmol, respectively. As expected, the optimized catalyst demonstrates remarkable OER performance in an alkaline solution with low overpotentials of 235 mV and 333 mV at high current densities of 50 mA cm−2 and 100 mA cm−2, respectively. Furthermore, the catalyst shows long-term stability lasting for 35 h at 60 mA cm−2 with a negligible shift in the polarization curve observed even after 2000 cyclic voltammetry cycles, while also exhibiting good structural preservation. The current study has the potential to offer valuable insights into the fabrication of electrocatalysts based on metal sulfide heterostructures. A simple hydrothermal-sulfurization strategy was adopted to fabricate series of self-supported iron-nickel sulfide nanosheet heterostructures catalysts with excellent OER performance. [Display omitted] • Self-supported Fe 1-x S-NiS/NF nanosheets were synthesized by sulfurization of carbonates. • Effects of sulfurization temperature and Fe content on the OER performance are investigated. • The Fe 1-x S-NiS/NF-2 catalyst exhibits excellent OER performance. [ABSTRACT FROM AUTHOR]

Developing highly efficient and stable electrocatalysts for urea electro-oxidation reactions (UORs) will improve wastewater treatment and energy conversion. A low-cost cobalt sulfide-anchored nickel sulfide electrode (CoS/Ni3S2@CP) was synthesized by electrodeposition in DMSO solutions and found to be highly effective and long-lasting. The morphology and composition of catalyst surfaces were examined using comprehensive physicochemical and electrochemical characterization. Specifically, CoS/Ni3S2@CP electrodes require a potential of 1.52 volts for a 50 mA/cm2 current, confirming CoS in the heterointerface CoS/Ni3S2@CP catalyst. Further, the optimized CoS/Ni3S2@CP catalyst shows a decrease of 100 mV in the onset potential (1.32 VRHE) for UORs compared to bare Ni3S2@CP catalysts (1.42 VRHE), demonstrating much greater performance of UORs. As compared to Ni3S2@CP, CoS/Ni3S2@CP exhibits twofold greater UOR efficiency as a result of a larger electroactive surface area. The results obtained indicate that the synthetic CoS/Ni3S2@CP catalyst may be a favorable electrode material for managing urea-rich wastewater and generating H2. [ABSTRACT FROM AUTHOR]