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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]

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]

Enhanced electrocatalysts that are cost‐effective, durable, and derived from abundant resources are imperative for developing efficient and sustainable electrochemical water–splitting systems to produce hydrogen. Therefore, the design and development of non–noble–based catalysts with more environmentally sustainable alternatives in efficient alkaline electrolyzers are important. This work reports ferrocene (Fc)‐incorporated nickel sulfide nanostructured electrocatalysts (Fc−NiS) using a one–step facile solvothermal method for water–splitting reactions. Fc−NiS exhibited exceptional electrocatalytic activity under highly alkaline conditions, evident from its peak current density of 345 mA cm−2, surpassing the 153 mA cm−2 achieved by the pristine nickel sulfide (NiS) catalysts. Introducing ferrocene enhances electrical conductivity and facilitates charge transfer during water–splitting reactions, owing to the inclusion of iron metal. Fc−NiS exhibits a very small overpotential of 290 mV at 10 mA cm−2 and a Tafel slope of 50.46 mV dec−1, indicating its superior charge transfer characteristics for the three–electron transfer process involved in water splitting. This outstanding electrocatalytic performance is due to the synergistic effects embedded within the nanoscale architecture of Fc−NiS. Furthermore, the Fc−NiS catalyst also shows a stable response for the water–splitting reactions. It maintains a steady current density with an 87% retention rate for 25 hours of continuous operation, indicating its robustness and potential for prolonged electrolysis processes. [ABSTRACT FROM AUTHOR]

The overconsumption of fossil fuels is leading to worsening environmental damage, making the generation of clean, renewable energy an absolute necessity. Two common components of electrochemical energy storage (EES) devices are batteries and supercapacitors (SCs), which are among the most promising answers to the worldwide energy issue. In this study, we introduce an exceptionally efficient electrode material for supercapacitors, composed of a hydrothermally synthesized composite known as MnNiS@MXene. We utilized XRD, SEM, and BET to analyze the material's crystallinity, morphology, and surface area. The Qs of MnNiS@MXene was a remarkable 1189.98 C/g or 1983.3 F/g at 2 A/g under three electrode assemblies in 1 M KOH electrolyte solution. Activated carbon was used as the negative electrode, while MnNiS@MXene served as the positive electrode in the assembled supercapattery device (MnNiS@MXene//AC). This device showed exceptional performance, a specific capacity of 307.18 C/g, a power density of 1142.61 W/kg, and an energy density of 34.79 Wh/kg. Additionally, cyclic durability was evaluated through 7000 cycles of charging/discharging, demonstrating that it maintained approximately 87.57% of its original capacity. The successful integration of these materials can lead to electrodes with superior energy storage capabilities and efficient photoelectrochemical performance. The aforementioned findings suggest that MnNiS@MXene exhibits promising potential as an electrode material for forthcoming energy storage systems. [ABSTRACT FROM AUTHOR]

Due to their high energy density and cost‐effectiveness, lithium–sulfur batteries (LSBs) are considered highly promising for the next generation of energy storage technologies. However, the soluble lithium‐polysulfides (LiPSs) notorious for causing the shuttle effect and the sluggish redox kinetics have hindered their practical commercialization. To tackle these challenges, a heterostructural catalyst featuring NiS‐NiCo2O4 interfaces is developed, which serves as an interlayer for LSBs. These interfacial sites leverage the advantages of polar NiCo2O4 and conductive NiS, enabling smooth Li+ diffusion, rapid electron transport, and effective immobilization of LiPSs. This synergistic approach promotes the conversion of sulfur species, resulting in a high discharge capacity of 526 mAh g−1 at 3 C for cells with the NiS‐NiCo2O4 interlayer. Additionally, remarkable cycling stability is achievable with an areal sulfur loading of ≈5.0 mg cm−2. It is believed that this research paves the way for practical applications of LSBs. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate an interface on porous nickel foam (NN) between crystalline nickel sulfide and amorphous nickel sulfide (NNS/NNSx) adapting simple hydrothermal and facile electrodeposition processes, respectively. The developed electrocatalyst required a low overpotential of 15 mV to deliver a current density of 10 mA cm−2 and the interface intrinsically activates the electrocatalyst with an onset overpotential comparable to that of Pt in an alkaline hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

Transition metal chalcogenides have been identified as low-cost and efficient electrocatalysts to promote the hydrogen evolution reaction in alkaline media. However, the identification of active sites and the underlying catalytic mechanism remain elusive. In this work, we employ operando X-ray absorption spectroscopy and near-ambient pressure X-ray photoelectron spectroscopy to elucidate that NiS undergoes an in-situ phase transition to an intimately mixed phase of Ni3S2 and NiO, generating highly active synergistic dual sites at the Ni3S2/NiO interface. The interfacial Ni is the active site for water dissociation and OH* adsorption while the interfacial S acts as the active site for H* adsorption and H2 evolution. Accordingly, the in-situ formation of Ni3S2/NiO interfaces enables NiS electrocatalysts to achieve an overpotential of only 95 ± 8 mV at a current density of 10 mA cm−2. Our work highlighted that the chemistry of transition metal chalcogenides is highly dynamic, and a careful control of the working conditions may lead to the in-situ formation of catalytic species that boost their catalytic performance. Transition metal chalcogenides are effective and economical electrocatalysts for the hydrogen evolution reaction in alkaline media, yet active sites and catalytic mechanisms remain unclear. Here the authors use operando spectroscopy to study the in-situ conversion of NiS to highly active Ni3S2/NiO dual-site catalysts for the alkaline hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

The severe Zn‐dendrite growth and insufficient carbon‐based cathode performance are two critical issues that hinder the practical applications of flexible Zn‐ion micro‐ssupercapacitors (FZCs). Herein, a self‐adaptive electrode design concept of the synchronous improvement on both the cathode and anode is proposed to enhance the overall performance of FZCs. Polypyrrole doped with anti‐expansion graphene oxide and acrylamide (PPy/GO‐AM) on the cathode side can exhibit remarkable electrochemical performance, including decent capacitance and cycling stability, as well as exceptional mechanical properties. Meanwhile, a robust protective polymeric layer containing reduced graphene oxide and polyacrylamide is self‐assembled onto the Zn surface (rGO/PAM@Zn) at the anode side, by which the "tip effect" of Zn small protuberance can be effectively alleviated, the Zn‐ion distribution homogenized, and dendrite growth restricted. Benefiting from these advantages, the FZCs deliver an excellent specific capacitance of 125 mF cm−2 (125 F cm−3) at 1 mA cm−2, along with a maximum energy density of 44.4 µWh cm−2, and outstanding long‐term durability with 90.3% capacitance remained after 5000 cycles. This conformal electrode design strategy is believed to enlighten the practical design of high‐performance in‐plane flexible Zn‐based electrochemical energy storage devices (EESDs) by simultaneously tackling the challenges faced by Zn anodes and capacitance‐type cathodes. [ABSTRACT FROM AUTHOR]

Sulfide all‐solid‐state battery (SASSB) with ultrahigh‐nickel layered oxide cathode (LiNixCoyMn1‐x‐yO2, NCM, x ≥ 0.9) offers the potential of high energy density and safety for superior energy storage systems. However, stable cycling is difficult to realize due to adverse interfacial reactions, space charge layer (SCL), and elemental diffusion. Herein, a straightforward solid‐phase coating strategy is exploited to synthesize Ni90‐S cathode, which greatly improves the charge transmission capability of the composite cathode and suppresses interfacial reactions in SASSB. The consequent SC‐Ni90‐0.2%S/Li6PS5Cl/Li4Ti5O12 SASSB exhibits enhanced electrochemical performance, including a long life of 500 cycles with 87% capacity retention at 1C, high areal capacity of 11.44 mAh cm−2, and excellent rate performance at 20 C. These results promise an efficient strategy for designing cathode materials for SASSBs. [ABSTRACT FROM AUTHOR]

This article reports a simple hydrothermal method for synthesizing nickel disulfide (NiS2) on the surface of fluorine-doped tin oxide (FTO) glass, followed by the deposition of 5 nm Au nanoparticles on the electrode surface by physical vapor deposition. This process ensures the uniform distribution of Au nanoparticles on the NiS2 surface to enhance its conductivity. Finally, an Au@NiS2-FTO electrochemical biosensor is obtained for the detection of dopamine (DA). The composite material is characterized using transmission electron microscopy (TEM), UV-Vis spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical properties of the sensor are investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and time current curves in a 0.1 M PBS solution (pH = 7.3). In the detection of DA, Au@NiS2-FTO exhibits a wide linear detection range (0.1~1000 μM), low detection limit (1 nM), and fast response time (0.1 s). After the addition of interfering substances, such as glucose, L-ascorbic acid, uric acid, CaCl2, NaCl, and KCl, the electrode potential remains relatively unchanged, demonstrating its strong anti-interference capability. It also demonstrates strong sensitivity and reproducibility. The obtained Au@NiS2-FTO provides a simple and easy-to-operate example for constructing nanometer catalysts with enzyme-like properties. These results provide a promising method utilizing Au coating to enhance the conductivity of transition metal sulfides. [ABSTRACT FROM AUTHOR]

Facing the situation of nickel resource shortage and increasing nickel demand, it is an important task for the development of nickel industry to realize efficient utilization of low-grade nickel sulfide ore. In this work, the process of NaCl roasting-water leaching was proposed to simultaneously extract valuable metals from low-grade nickel concentrate. Based on the thermodynamic analysis of roasting process, the effect of several key factors on metal extraction was investigated. The results show that the extraction of Ni, Cu and Co can reach approximately 94.08, 92.81 and 91.85 pct, respectively, under the following optimum conditions: temperature 400 °C, time 90 minutes, NaCl dosage 100 pct and concentrate particle size 70–88 µm. The evolution behavior and mechanism of metallic minerals are determined through thermodynamic analysis, differential thermogravimetric analysis, and phase composition analysis of roasted product. The kinetics of the roasting process based on the differential thermal and thermogravimetric experiment was analyzed by Kissinger method and Doyle-Ozawa method. The average apparent activation energy of metallic minerals being chlorinated is determined as 400.12 kJ/mol and the kinetic equation was expressed as d α dt = 2.41 × 10 12 e - 400.12 RT (1 - α) 1.27 . [ABSTRACT FROM AUTHOR]

Poly (3‐methylthiophene) (P3MT) was modified by nickel oxide (NiO) and nickel sulfide (NiS) nanoparticles to enhance its electrochemical performance. The surface influence, crystalline structure, and electrochemical performance of the P3MT/NiO/NiS material were characterized and compared with that of pristine P3MT. It is found that surface modification can improve the structural stability of P3MT without decreasing its available specific capacitance. The electrochemical properties of synthesized P3MT/NiO/NiS electrode were evaluated using cyclic voltammetry and alternating current impedance techniques in 3 M KOH electrolyte. Specific capacitances of 253, 764, 932, and 1434 F g−1 were obtained for P3MT, P3MT/NiO, P3MT/NiS, and P3MT/NiO/NiS, respectively at 5 A g−1. This improvement is attributed to the synergistic effect of Ni2+ ions in the P3MT/NiO/NiS electrode material. The P3MT/NiO/NiS electrode in KOH has average specific energy and specific power densities of 1032 Wh kg−1 and 6192 W/kg, respectively. Only 2% of the capacitance's initial value is lost after 10,000 cycles. The resulting P3MT/NiO/NiS nanocomposite had very stable and porous layered structures. This work demonstrates that P3MT/NiO/NiS nanomaterials exhibit good structural stability and electrochemical performance, and are good material for supercapacitor applications. Highlights: The P3MT/NiO/NiS nanocomposite is fabricated and characterized as supercapacitor electrode.The incorporation of NiO/NiS in the poly (3‐methylthiophene) has improved the electrochemical performance.The P3MT/NiO/NiS electrodes retained 98% of their specific capacitance after 10,000 cycles.The P3MT/NiO/NiS nanocomposite electrode showed specific capacitance of 1434 F g−1 at 5 A g−1.The stability of the nanocomposite was enhanced without altering its morphology and chemical structure. [ABSTRACT FROM AUTHOR]

In the present work, a novel composite of nickel sulfide (NiS) and potato peel‐derived carbon spheres (NiS/PPCS) with higher specific capacitance and cyclic performance was synthesized as electrode material for supercapacitor applications. The composite was deposited on a graphite rod to be use as an electrode. The electrochemical performance studies using CV, GCD, and EIS revealed that the prepared electrode showed an improved current response and higher specific capacitance than the pristine NiS electrode. The maximum specific capacitance for the NiS/PPCS electrode was found to be 2185 F/g at 0.2 A/g current density. More precisely, it was observed that the NiS/PPCS composite exhibited an excellent retention capacity of 95.04% after 20 000 continuous charge‐discharge cycles, showing its exceptional cyclic performance. The impedance studies revealed that the reaction between the NiS/PPCS electrode and electrolyte was rapid and highly reversible. Based on the findings of the electrochemical performances, NiS/PPCS electrode appears to be a potential candidate for highly efficient and economical asymmetric supercapacitors. [ABSTRACT FROM AUTHOR]

The metal–organic framework (MOF) materials with significant steadiness and a large specific surface area have been popular with supercapacitor material in recent years. However, its application in supercapacitors is restricted due to the low specific capacitance and poor conductivity. Herein, sulfur compounds with a high theoretical specific capacitance and highly conductive titanium nitride (TiN) were introduced into Co-based metal–organic frameworks/nickel foam (Co-MOF/NF) through a two-step hydrothermal technique (nickel sulfide/titanium nitride@ Co-based metal–organic frameworks/nickel foam). In detail, the fabricated nickel sulfide/titanium nitride@Co-based metal–organic frameworks/nickel foam (Ni3S2/TiN@Co-MOF/NF) electrode material exhibits a markedly high specific capacitance (2648.8 F g−1) at 1 A g−1, compared with that (770 F g−1) of the precursor Co-MOF/NF. And its mass specific capacitance is retained 88.3% (8 A g−1) after 5000 cycles. Furthermore, a non-symmetrical supercapacitor (ASC) composed of Ni3S2/TiN@Co-MOF/NF and AC exhibits excellent power density (801.8 W kg−1) and energy density (97.8 W h kg−1). Therefore, Ni3S2/TiN@Co-MOF/NF with excellent electrochemical properties and stability provides new ideas for the development of excellent supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

To revolutionize the photochemical efficiency of quantum dots sensitized solar cells (QDSSCs) devices, herein, a passivation of the cells with multilayer material has been developed for heterojunctions TiO2/NiS/MnS/HI-30/Pt devices. In this study, NiS and MnS were deposited on a photoanode for the first time as passivated photon absorbers at room temperature. The adoption of NiS as a passisvative layer could tailor the active surface area and improve the photochemical properties of the newly modified cells. The vibrational shifts obtained from the Raman spectra imply that the energy change is influenced by the surface effect, giving rise to better electronic conductivity. The electrochemical stability and durability test for the N/M-3 device slows down and remains at 8.88% of its initial current after 3500 s, as compared to the N/M-1 device at 7.20%. The disparity in charge recombination implies that both the outer and inner parts of the nanoporous material are involved in the photogeneration reaction. The hybridized N/M-3 cell device reveals the highest current density with a low potential onset, indicating that power conversion occurs more easily because photons tend to be adsorbed easily on the surface of the MnS. The Nyquist plot for N/M-1 and N/M-3 promotes the faster transport of electrolytic ions across the TiO2/NiS/MnS, providing a good interaction for the electrolyte. The I-J Value of 9.94% shows that the passivation with the NiS layer promotes electron transport and enhances the performance of the modified cells. The passivation of the TiO2 layer with NiS attains a better power conversion efficiency among the scant studies so far on the surface passivation of QDSCs. [ABSTRACT FROM AUTHOR]

Supercapacitors are useful for storing and delivering more energy in smaller footprints. Developing high-energy-density supercapacitors enables more efficient utilization of energy, improved performance, and a means for flexibly addressing diverse energy storage requirements. The electrode materials and the techniques used for their fabrication play a significant role in obtaining the desired operating performance of supercapacitors. The present study employs a novel, simple, scalable, and low-cost fabrication technique to synthesize nickel-cobalt sulfide (NiCo2S4) nanostructures on commercial nickel foam. Prominent morphological and electrochemical characterization techniques were used to assess the structural and operating performance of the synthesized nanostructure. The synergistic effects of nickel and cobalt transition metals resulted in enhanced performance of the nanostructure. The synthesized nanostructure was further employed in a symmetric supercapacitor device. Surface morphological and electrochemical experiments showed an energy density value of 62.8 Wh/kg and retention capacity of 94% even after 8000 cycles. The electrochemical characteristics were validated using electrical experiments as well. The high specific capacitance, faster electron and ion transfer, and improved structural integrity obtained for the supercapacitor indicate its suitability for enhanced energy storage applications. [ABSTRACT FROM AUTHOR]

Supercapatteries are contemporary electrochemical energy‐storage devices that bridge the gap between the conventional supercapacitors and rechargeable batteries. Supercapatteries utilize battery‐type electrode‐active materials for their charge storage. Among the various futuristic materials, transition‐metal dichalcogenides receive prominent attention due to their excellent charge‐storage capabilities. Herein, the microwave‐assisted hydrothermal synthesis of layered two‐dimensional (2D) nickel sulfide nanosheets (NSN) and their application as electrode‐active materials in high‐performance asymmetric supercapatteries are reported. The layered 2D architecture is preferred for the electrode‐active materials as the layered electrode nanostructure provides a hindrance‐free movement to the electrolyte ions through it during the charge‐storage process that include intercalation/deintercalation mechanisms. The electrochemical thermal stability of the 2D NSN electrode reveals that its stability in KOH (aqueous) electrolyte is better than that in LiOH (aqueous) and NaOH (aqueous) electrolytes. The supercapattery electrode synthesized using 2D NSN exhibits excellent electrochemical charge‐storage performances bearing a maximum specific capacity of 594.77 C g−1 (an equivalent mass‐specific capacitance of 991.29 F g−1) in 2 M KOH (aqueous) electrolyte. The electrochemical cycling performance of the 2D NSN electrode shows a stability over 40 000 cycles without any significant capacity loss. An asymmetric supercapattery device fabricated with 2D NSN electrode as positrode and activated carbon as negatrode exhibits a maximum mass‐specific capacity of 143.58 C g−1 with a corresponding energy density of 29.91 Wh kg−1 in 2 M KOH (aqueous) electrolyte. [ABSTRACT FROM AUTHOR]

In recent decades, photocatalysis technology, a typical mild and environmentally friendly technique, can use sunlight to drive the oxidation/reduction reactions on the surface of catalysts. However, single semiconductor materials can hardly meet the requirements of photocatalytic application due to the low availability of visible light, quick e− − h+ recombination, and the insufficiency of active sites. Cocatalysts are often introduced to solve the above problems. Among the numerous cocatalysts, NiS cocatalysts exhibit excellent properties, such as superior chemical stability, suitable band structure, and larger specific surface area, which can improve the photocatalytic efficiency of various semiconductors. Herein, the research progress of NiS cocatalysts in photocatalysis is reviewed. First, the structure of NiS and several common preparation methods are briefly introduced. Second, the NiS cocatalytic principle about how to achieve the effective separation of photogenerated carriers is introduced. Third, the methods to optimize the catalytic activity of NiS are mainly summarized. At the same time, the review summarizes the research progress of composite photocatalysts based on NiS cocatalyst. Finally, the review discusses the existing challenges and obstacles of NiS‐based photocatalytic systems and proposes feasible improvements and ideas to meet the future requirements of practical applications. [ABSTRACT FROM AUTHOR]

Given the energy crisis and escalating environmental pollution, the imperative for developing clean new energy is evident. Hydrogen has garnered significant attention owing to its clean properties, high energy density, and ease of storage and transportation. This study synthesized four types of catalysts—FeS(DI/MB), FeS(ET/MB), Fe(DI/MB), and Fe(ET/MB)—using two distinct solution systems: DI/MB and ET/MB. The FeS(DI/MB) catalyst, synthesized using the layered solution system (DI/MB), demonstrates a uniformly distributed and dense nanosheet structure, exhibiting excellent resistance to strong bases and superior catalytic properties. The FeS(DI/MB) electrode showed OER overpotentials of 460 mV and 318 mV in 1 M and 6 M, respectively, at current densities of up to 500 mA cm−2. Under industrial electrolysis test conditions, the FeS(DI/MB) electrode required only 262 mV to achieve a current density of 500 mA cm−2, operating in a high-temperature, strong alkaline environment of 6 M at 60 °C. Furthermore, the FeS(DI/MB) electrode exhibited excellent OER catalytic activity and stability, as evidenced by a 60 h stability test These findings provide valuable insights into the preparation of iron nickel sulfide-based catalysts, and further in-depth and comprehensive exploration is anticipated to yield the excellent catalytic performance of these catalysts in the realm of electrolytic water hydrogen production. [ABSTRACT FROM AUTHOR]

Heavy oils are characterized by a high content of resins and asphaltenes, which complicates refining and leads to an increase in the cost of refinery products. These components can be strongly adsorbed on the acid sites of a supported catalyst, leading to its deactivation. Currently, various salts of group 8 metals are being considered for such processes to act as catalysts during oil cracking. At the same time, the nature of the precursor often has a significant impact on the process of refining heavy oil. In this work, catalytic cracking of heavy oil from the Ashalchinskoye field using different precursors (nanodispersed catalysts formed in situ based on NiO) has been studied. The cracking was carried out at 450 °C with a catalyst content from 0.1 to 0.5 wt.%. The catalytic cracking products were analyzed via SARA, GC, XRD and SEM. Nickel acetate and nitrate promote similar yields of by-products, while formate promotes higher yields of gaseous products. Formate and nickel acetate were shown to produce 1.8 and 2.8 wt.% more light fractions than nickel nitrate. When heavy oil is cracked in the presence of Ni(NO3)2∙6H2O, the maximum decrease in sulfur content (2.12 wt.%) is observed compared to other precursors. It has been found that the composition and morphology of the resulting nickel sulfides and compaction products are influenced by the nature of the catalyst precursor. XRD and SEM analyses of coke-containing catalysts indicate the formation of Ni9S8 and Ni0.96S phases during cracking when nickel nitrate is used and the formation of NiS and Ni9S8 when nickel acetate and formate are used. [ABSTRACT FROM AUTHOR]

Nickel has excellent physicochemical properties and a wide range of applications, nickel resources are mainly found in nickel sulfide ores and nickel laterite ores, and nickel laterite ores are gradually becoming the main raw materials for nickel extraction. Due to the high water-content of nickel laterite ores, high temperature pre-treatment of the ores is usually required in the smelting process to remove hydroxylated water in the lattice of the ores and to prereduction of part of the metal, but this part of the hydroxylated water removal needs to consume a lot of energy and produce physical phase changes, which will affect the prereduction and leaching. However, the removal of this part of hydroxyl water needs to consume a large amount of energy, and produces physical phase changes, which will have an impact on the prereduction and leaching, so it is important to investigate the physical phase changes and kinetic conditions of the dehydroxylation process of nickel laterite ores for the subsequent processing operations. In this paper, the possible chemical reactions during the heating process of nickel laterite ore were simulated and calculated using thermodynamic analysis software, and the physical phase changes during the heating process of nickel laterite ore of silica-magnesium type were investigated using thermogravimetric-differential thermal analysis and XRD analysis, and nonisothermal kinetic experiments were carried out at five heating rates from room temperature to 1 400 °C. Three characteristic peaks were observed at 256.8, 582.8 and 823.0 °C, corresponding to the fuselage dehydroxylation process. The three characteristic peaks corresponding to the dehydroxylation of limonite, dehydroxylation of serpentine, and phase transformation of silicate minerals respectively. A nonisothermal kinetic model solution was used to determine the apparent activation energy and the finger front factor of the reaction. The activation energy of the serpentine dehydroxylation process was calculated by using the Flynn-Wall-Ozawa method and the Kissinger Akahira-Sunose method, and 30 commonly used mechanistic functions were fitted by using the Satava-Sestak method, and the eligible mechanistic functions were retained. The A1/3 function of the Avrami-Erofeev equation was determined to be consistent with the dehydroxylation process, and is integral form was G(α) = + - ln (1-α)] ³, which yielded the activation energy of the serpentine dehydroxylation reaction to be 258.71 kj/mol, lnA being 28.94, and the average linear correlation coefficient of 0.995 1. The serpentine dehydroxylation process is consistent with stochastic nucleation and subsequent growth of serpentines. The process is consistent with the stochastic nucleation and subsequent growth model. [ABSTRACT FROM AUTHOR]

In order to improve the pseudocapacitance performance of metal sulfide electrode materials and obtain supercapacitor energy storage devices with excellent electrochemical reversibility and long-term cycle stability, the synthesis of flower-shaped crystal nickel–cobalt sulfide and its supercapacitor performance were studied. NiCo2S4 flower-shaped crystal nickel–cobalt sulfide was prepared by the hydrothermal method with nickel foam as the raw material, and electrode materials were added to prepare supercapacitor electrodes for testing of the supercapacitor performance. The physical properties of flower-shaped crystal nickel–cobalt sulfide were tested by a scanning electron microscope and transmission electron microscope, and the voltammetric cycle and constant current charge and discharge of supercapacitor electrodes prepared from this sulfide were analyzed through experiments. The experimental results showed that the flower crystal microstructure had a positive effect on the electrochemical properties. The capacitance value was always high at different current densities, and the capacity was as high as 3867.8 A/g at pH 12. After 2000 voltage–charge–discharge cycle tests, the petal-like sulfide capacity still had a retention rate of 90.57, the flower crystal nickel–cobalt sulfide still showed an excellent supercapacitor performance and the specific capacity was still high, which demonstrates that this sulfide has excellent cyclic stability and durability in electrochemical applications. [ABSTRACT FROM AUTHOR]

To increase the effectiveness of both the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER), significant efforts are made to produce bifunctional water‐splitting electrocatalysts. In this study, bismuth oxide/nickel oxide (Bi2O3/NiO)‐based composite is supported over the nickel foam (Bi2O3/NiO‐NF) and carbon nanotube fiber (Bi2O3/NiO‐CNTF) to develop two different electrode systems for water‐splitting studies. For OER, Bi2O3/NiO‐NF and Bi2O3/NiO‐CNTF require overpotential of 401 and 369 mV, respectively, to achieve the current density of 50 mA cm−2 in alkaline media, while the current density of 50 mA cm−2 is achieved at overpotential of 398 and 304 mV, respectively, in neutral media. For HER, Bi2O3/NiO‐NF and Bi2O3/NiO‐CNTF achieve the current density of 50 mA cm−2 at overpotential of 301 and 268 mV, respectively, in neutral media. For overall water splitting in neutral media, Bi2O3/NiO‐CNTF achieves the current density of 50 mA cm−2 at cell voltage of 1.654 V. The promising performance of synthesized electrocatalysts reveals that the mixed metal oxides (p‐block and d‐block elements)‐based electrocatalysts can be potential candidates for practical water splitting in basic (1 M KOH) as well as neutral media (1 M phosphate‐buffered saline). [ABSTRACT FROM AUTHOR]

New data on the multiple sulfur isotope signature of Archean sulfides from country rocks and magmatic mineralization at the Moran deposit (Kambalda, Western Australia) were combined with previously published geochemical data to constrain the various stages of the dynamic evolution of this magmatic system, unveiling new insights into the transport mechanisms of sulfide liquids in komatiite magmas. Sulfides in the Archean magmatic and sedimentary host rocks of the komatiites display a unique mass-independent sulfur isotope signature (Δ33S), which records a photochemical reaction of sulfur in an oxygen-poor atmosphere prior to the Great Oxidation Event. Sedimentary rocks that are thought to be assimilated by komatiite show a distinctly positive Δ33S signature (+ 0.9 to + 2.4‰). Early ore sulfides situated above these sedimentary rocks contain relatively few valuable metals and display an overlapping Δ33S range (+ 0.6 to + 1.0‰). Subsequent but still early ore sulfides are situated above basalt, as the sedimentary rocks were thermo-mechanically eroded by the sulfide melt, displaying more mantle-like signatures (+ 0.2 to + 0.3‰) and valuable metal content - indistinguishable from the main ore deposit. This reflects a progressive dilution of the contaminant signature by the magmatic isotope signature of the komatiite liquid. Calculated volumes of the interaction of silicate melt and sulfide melt to explain the metal tenor of the ore and its Δ33S signature indicate a decoupling between chemical and isotopic signatures. This can be explained by upgrading the sulfide melt with valuable metals simultaneously with the dissolution of sulfur in the komatiite melt. [ABSTRACT FROM AUTHOR]

The design and development of high‐efficiency and low‐energy consumption catalysts for hydrogen evolution are critical to mitigating environmental problems. Herein, amorphous Co9S8 quantum dots (QDs) are prepared by hydrothermal method and loaded on concave cubic NiS/CdS derived from Prussian blue analog (PBA) to construct an efficient Co9S8 QDs/NiS/CdS dual S‐scheme heterojunction photocatalysts, showing excellent photocatalytic hydrogen performance of 13.45 mmol·g−1·h−1, which is 5.42 times higher than that of pure CdS. The improved photocatalytic performance is ascribed to the creation of a double S‐scheme heterojunction, quantum confinement effect, and a concave cubic structure, accelerating electron transport and offering ample surface active sites. The possible mechanism is demonstrated with valence band XPS (VB‐XPS), ultraviolet photoelectron spectroscopy (UPS), and density functional theory (DFT) calculations. This work provides insight into the exploration of PBA‐based photocatalysts to improve photocatalytic hydrogen evolution and provides an effective strategy for the design of photocatalysts with double the S‐scheme heterojunction. [ABSTRACT FROM AUTHOR]

A bifunctional electrocatalyst with high efficiency and low costs for overall water splitting is critical to achieving a green hydrogen economy and coping with the energy crisis. However, developing robust electrocatalysts still faces huge challenges, owing to unsatisfactory electron transfer and inherent activity. Herein, NiFe LDH/NiS2/VS2 heterojunctions have been designed as freestanding bifunctional electrocatalysts to split water, exhibiting enhanced electron transfer and abundant catalytic sites. The optimum NiFe LDH/NiS2/VS2 electrocatalyst exhibits a small overpotential of 380 mV at 10 mA cm−2 for overall water splitting and superior electrocatalytic performance in both hydrogen and oxygen evolution reactions (HER/OER). Specifically, the electrocatalyst requires overpotentials of 76 and 286 mV at 10 mA cm−2 for HER and OER, respectively, in alkaline electrolytes, which originate from the synergistic interaction among the facilitated electron transfer and increasingly exposed active sites due to the modulation of interfaces and construction of heterojunctions. [ABSTRACT FROM AUTHOR]

At present, the rational design and facile synthesis of highly active and low-cost photocatalysts are still facing great challenges. Herein, a series of Zn0.5Cd0.5S/NiS (x mol%) composite photocatalysts have been synthesized via a simple and mild one-pot hydrothermal method. Compared with pure Zn0.5Cd0.5S, the NiS-loaded samples exhibit enhanced photocatalytic hydrogen generation performance, in which the Zn0.5Cd0.5S/NiS-5% sample has the highest H2 production rate of 10 855 ± 461 μmol h−1 g−1 with a quantum yield of 11.82% at 365 nm, which is almost 6.3 times higher than that of pristine Zn0.5Cd0.5S. The high activity of the Zn0.5Cd0.5S/NiS nanosheets may be attributed to their distinct nanostructure, including a short transfer distance of photoinduced charge carriers, a large number of unsaturated surface atoms, and a large surface area. Moreover, the added NiS nanoparticles served as an effective cocatalyst to promote photoinduced electron transfer and enhance the surface kinetics of H2 evolution. Our work provides a simple and effective route for the preparation of sulphur-based photocatalysts, which can significantly improve the efficiency of hydrogen production from water. [ABSTRACT FROM AUTHOR]

We report the synthesis of a new nickel(II) hydroxide complex 2 supported by a rigid, tridentate triazolylidene-carbazolid ligand. The complex can be accessed in high yields following a simple and stepwise extraction protocol using dichloromethane and aqueous ammonium chloride followed by aqeous sodium hydroxide solution. We found that complex 2 is highly basic, undergoing various deprotonation/desilylation reactions with E–H and C–H acidic and silylated compounds. In this context we synthesized a variety of novel, functionalized nickel(II) complexes with trimethylsilylolate (3), trityl sulfide (4), tosyl amide (5), azido (6), pyridine (7), acetylide (8, 9), fluoroarene (10 & 11) and enolate (12) ligands. We furthermore found that 2 reacts with malonic acid dimethyl ester in a knoevennagel-type condensation reaction, giving access to a new enolate ligand in complex 13, consisting of two malonic acid units. Furthermore, complex 2 reacts with acetonitrile to form the cyanido complex 14. The formation of complexes 13 and 14 is particularly interesting, as they underline the potential of complex 2 in both C–C bond formation and cleavage reactions. [ABSTRACT FROM AUTHOR]

Nanomaterials synergy in a binary system offers a great opportunity for the development of high-performance electrode material for Lithium-ion batteries (LiBs). So far SnS/Ni3S4 binary sulfides are scarcely investigated as an anode for LIBs. In this work, to intrinsically enhance the kinetics of SnS, SnS/Ni3S4 (SN-x) binary sulfides were synthesized by introducing nickel sulfide with different stoichiometric ratios (0.5, 1, 2, and 3). The developed electrode (SN-2) delivers an initial discharge capacity of 2567 mA h g−1 and a high reversible capacity of 360 mA h g−1 at a current rate of 300 mA g−1 after 180 cycles with a Coulombic efficiency of over 97%. The electrochemical impedance spectroscopy (EIS) and density functional theory (DFT) confirm the improved kinetics of the SN-2 electrode as compared to other electrodes. The significantly enhanced performance of the SN-2 electrode can be attributed to the addition of an optimized amount of Ni3S4, synergistic effects between SnS and Ni3S4, generation of more active sites and structural integrity. This work suggests that the prepared SnS/Ni3S4 binary sulfides exhibit great promise for the development of efficient energy storage devices. [ABSTRACT FROM AUTHOR]

The achievement of the outstanding theoretical capacitance of nickel sulfide (NiS2) is challenging due to its low conductivity, slow electrochemical kinetics, and poor structural stability. In this study, we utilize polyaniline (PANI) as a linker to anchor the NiS2 with a hollow bowl‐like structure, uniformly dispersed at the surface of graphene oxide (GO)(NiS2@15PG). The presence of PANI provides growth sites, resulting in a uniform and dense arrangement of NiS2. This morphological modulation of NiS2 increases the contact area between the active material to electrolyte. Additionally, PANI effectively connects NiS2 with the conductive network of GO, which advances the electrical conductivity and ion diffusion properties. As a result, the Rct (charge transfer resistance) and Zw (Warburg impedance) of NiS2@15PG decrease by 82.61 % and 66.76 % respectively. This unique structure confers NiS2@15PG with high specific capacitance (536.13 C g−1 at 1 A g−1) and excellent multiplicative property of 60.93 % at 20 A g−1. The assembled NiS2@15PG//YP‐50 supercapacitors (HSC) demonstrates an energy density (13.09 Wh kg−1) at a high‐power density (16 kW kg−1). The capacity retention after 10,000 cycles at 5 A g−1 is 86.59 %, indicating its significant potential for practical applications. [ABSTRACT FROM AUTHOR]

We present a carbonation-assisted flotation method for nickel (Ni) separation from low-grade ultramafic ores. The high process economics of conventional flotation of low-grade ultramafic ores makes Ni unrecoverable on an industrial scale. Based on the fundamentals of CO2 sequestration in minerals, we carbonated a low-grade serpentine (lizardite) ore specimen under extreme conditions (185 °C, 15 MPa, and 24 h) and attained a conversion efficiency of serpentine to magnesite of 22% and 16% in the presence and absence of inorganic salts, respectively. Rhombohedral structures on carbonated particles detected using scanning electron microscopy suggested the formation of magnesite. We also found that Ni–Fe existed as sulfides, as confirmed by elemental mapping micrographs, and did not leach out as Ni2+ and Fe2+, as confirmed through carbonation supernatant analysis. Here, we introduced Denver cell froth flotation experiments after carbonation, which showed that the carbonated ore in the presence of inorganic salts had 29% higher Ni recovery and 0.15 wt% higher nickel grade than the uncarbonated ore. This study is the first to successfully show that the carbonation of serpentine containing nickel-bearing pentlandite leads to magnesite formation, does not lead to the dissolution of nickel sulphide, and enhances the nickel separation efficiency during froth flotation. This study paves the path forward for the integration of mineral carbonation in the processing of low-grade ultramafic nickel ores. [ABSTRACT FROM AUTHOR]

The objective of this work was to prepare and evaluate Ni3S4/graphene nanostructures for making high-performance supercapacitor electrodes. A one-pot solvothermal method was developed to prepare the hierarchical nanostructures consisting of Ni3S4 nanoflowers on graphene nanosheets. Due to the hierarchical structure of Ni3S4 nanoflowers on graphene nanosheets, the resulting electrodes exhibited high supercapacitive performance. Herein, the Ni3S4/graphene electrode demonstrated the specific capacitance of 978.4 F g–1 at the current density of 0.5 A g–1, the rate capability and long-term cycling stability were also excellent. Moreover, the capacitance contribution of NG-60 can reach 87.9% of the total capacity at 10 mV s−1. The high pseudo-capacitive performance can be attributed to the superior electronic conductivity of graphene nanosheets and the well interconnected tiny pores/channels in the Ni3S4 nanoflower arrays. The prepared Ni3S4/graphene hierarchical nanostructures may be promising as innovative electrode materials for making high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Hydrogen energy plays an important role in clean energy system and is considered the core energy source for future technological development owing to its lightweight nature, high calorific value, and clean combustion products. The electrocatalytic conversion of water into hydrogen is considered a highly promising method. An electrocatalyst is indispensable in the electrocatalytic process, and finding an efficient electrocatalyst is essential. However, the current commercial electrocatalysts (such as Pt/C and Ru) are expensive; therefore, there is a need to find an inexpensive and efficient electrocatalyst with high stability, corrosion resistance, and high electrocatalytic efficiency. In this study, we developed a cost-effective bifunctional electrocatalyst by incorporating molybdenum into nickel sulfide (Ni3S2) and subsequently tailoring its structure to achieve a one-dimensional (1D) needle-like configuration. The hydrogen production efficiency of nickel sulfide was improved by changing the ratio of Mo doping. By analyzing the electrochemical performance of different Mo-doped catalysts, we found that the Ni3S2-Mo-0.1 electrocatalyst exhibited the best electrocatalytic effect in 1 M KOH; at a current density of 10 mA cm−2, it exhibited overpotentials of 120 and 279 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively; at a higher current density of 100 mA cm−2, the HER and OER overpotentials were 396 and 495 mV, respectively. Furthermore, this electrocatalyst can be used in a two-electrode water-splitting system. Finally, we thoroughly investigated the mechanism of the overall water splitting of this electrocatalyst, providing valuable insights for future hydrogen production via overall-water-splitting.

In this work, we prepared and studied the physical properties of nickel sulfide (NiS) nanostructure thin films, which were deposited on heated glasses substrates (T = 250°C) using the spray pyrolysis technique (SPT)using different Precursor concentrations of these two solution sources: nickel nitrates hyxahydrate {(Ni(NO3)2.6H2O)=X} and thiourea {(CS(NH2)2)=Y}: {30% [X].70%[Y]}, {33%[X].76% [Y]}&{36% [X]. 63 % [Y]} with fixing the other remaining experimental conditions, and this is to understand more the role of the Precursor concentrations of the solutions on the physical properties of nickel sulfide thin films. The results of X-ray diffraction (DRX) analysis showed that all nickel sulfide (NiS) thin films samples are polycrystalline in a hexagonal phase and have a preferred orientation of (010). The Crystallite size (D) was estimated by The Debye–Scherrer’s relation, ranging from 9.915 nm to 22.148 nm. The emergence of the Ni-S bond corresponding to the frequency 668.563 cm–1 was confirmed by FTIR analysis. On the other hand, the energy of the band gaps varies for samples from 0.87, 0.88 to 0.92 eV. Finally, the Sheet resistance (Rsh) was measured using the four-point method, which it used to determine the conductivity of the samples. [ABSTRACT FROM AUTHOR]

Hydrogen evolution reaction (HER) through electrocatalytic water splitting is regarded as a promising route to produce hydrogen in a large scale. Designing a low-cost, large-scale, and highly active electrolytic hydrogen production catalyst is still a huge challenge. Incorporation of high-loading redox-active materials with small amounts of graphene is a general protocol to achieve high-performance catalysts. Herein, reduced graphene oxide (RGO) and Au NPs cocatalysts-modified NiS hybrid composite photocatalysts were successfully synthesized via a facile hydrothermal method for hydrogen evolution reaction (HER). XRD results suggest the NiS with rhombohedral phase (# JCPDS No. 65-2117). Both SEM and TEM results reveal that Au with NiS sample has clear spherical-shaped nanoparticles sizes in the range of 30–40 nm are coated on the rGO nanosheets. The estimated optical band gap energy is in the order of Au NPs/NiS@rGO (2.36 eV) < Nis@rGO (2.67 eV) < pure NiS (2.91 eV). The surface areas of NiS, NiS@rGO, and Au-NiS@rGO were calculated to be 64.58, 87.6, and 106.35 m2g−1, respectively. The Au-NiS@rGO exhibits significantly enhanced catalytic activity for hydrogen evolution reaction (HER) in both the acid and alkaline electrolytes in comparison with the pristine NiS. The Au-NiS@rGO delivers a striking catalytic kinetic metrics of a small Tafel slope of 54 mV dec−1, a low overpotential of 252 mV at a current density of 10 mA cm−2, and long operation stability of 4 day in the acid electrolyte. The improved HER activity of the Au-NiS@rGO hybrid composite catalyst is attributed to the synergistic effect of the surface plasmon resonance of Au NPs and enhanced electron transfer on RGO. This work could offer a facile and low-cost strategy for the construction of composite photocatalysts with high-efficiency hydrogen generation activity. [ABSTRACT FROM AUTHOR]

Zn-BTC (H3BTC refers to 1, 3, 5-benzoic acid) MOF was used as a self-template and a zinc source to prepare ZnS/NiS2 with a layered heterogeneous structure as a promising electrode material using cation exchange and solid-phase vulcanization processes. The synergistic effect of the two metal sulfides enhances the application of ZnS/NiS2. And the high specific surface area and abundant active sites further promote the mass/charge transfer and redox reaction kinetics. In the three-electrode system, the specific capacitance was as high as 1547 F/g at a current density of 1 A/g, along with satisfactory rate capability (1214 F/g at 6 A/g) and cycling performance. Coupled with activated carbon (AC), the prepared hybrid device (ZnS/NiS2 as the positive electrode and AC as the negative electrode) (ZnS/NiS2/AC) can be operated under a potential window of 1.6 V and provides a high energy density of 26.3 Wh/kg at a power density of 794 W/kg. Notably, the assembled ZnS/NiS2//AC showed little capacity degradation after 5000 charge/discharge cycles. [ABSTRACT FROM AUTHOR]

Hydrogen energy plays an important role in clean energy system and is considered the core energy source for future technological development owing to its lightweight nature, high calorific value, and clean combustion products. The electrocatalytic conversion of water into hydrogen is considered a highly promising method. An electrocatalyst is indispensable in the electrocatalytic process, and finding an efficient electrocatalyst is essential. However, the current commercial electrocatalysts (such as Pt/C and Ru) are expensive; therefore, there is a need to find an inexpensive and efficient electrocatalyst with high stability, corrosion resistance, and high electrocatalytic efficiency. In this study, we developed a cost-effective bifunctional electrocatalyst by incorporating molybdenum into nickel sulfide (Ni3S2) and subsequently tailoring its structure to achieve a one-dimensional (1D) needle-like configuration. The hydrogen production efficiency of nickel sulfide was improved by changing the ratio of Mo doping. By analyzing the electrochemical performance of different Mo-doped catalysts, we found that the Ni3S2 - Mo-0.1 electrocatalyst exhibited the best electrocatalytic effect in 1 M KOH; at a current density of 10 mA cm-2, it exhibited overpotentials of 120 and 279 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively; at a higher current density of 100 mA cm- 2, the HER and OER overpotentials were 396 and 495 mV, respectively. Furthermore, this electrocatalyst can be used in a two-electrode water-splitting system. Finally, we thoroughly investigated the mechanism of the overall water splitting of this electrocatalyst, providing valuable insights for future hydrogen production via overall-water-splitting. [ABSTRACT FROM AUTHOR]

The electrochemical nitrate reduction reaction (ENO3RR) is a green ammonia synthesis method under ambient conditions relative to the traditional Haber–Bosch technology, which does not require high-temperature or high-pressure conditions and can convert nitrate pollutants in the environment into value-added NH3, thus achieving a dual purpose. However, more electrocatalysts with a remarkable performance towards high-efficiency ENO3RR need to be developed. In this work, a Cu/NiO-NF composite electrocatalyst with a nanorod structure on nickel foam was successfully fabricated, which contains heterogeneous interfaces between Cu and NiO toward selective electrocatalytic nitrate reduction for ammonia synthesis. The steric nanorod morphology of the catalyst can significantly increase the surface area, expose more active sites, and improve the reaction activity. Moreover, the construction of the composite and the interface effectively boosts the synergistic effect of the active species Cu and NiO, which can regulate the electronic structure of the catalyst, expose more active sites, enhance the conductivity of the material, and accelerate the interfacial electron transfer, thereby further promoting the ENO3RR performance. This Cu/NiO-NF composite exhibits a high NH3 yield of 0.6 mmol h−1 cm−2 and up to 97.81% faradaic efficiency at the optimal applied potential of −1.0 V (vs. RHE) in a concentration of 0.1 M NO3−-containing 0.1 M PBS. Furthermore, it demonstrates excellent electrochemical cycle stability. This work provides insights into the rational design and fabrication of ENO3RR electrocatalysts for potential electrocatalytic applications. [ABSTRACT FROM AUTHOR]

Optical anisotropy offers a heightened degree of flexibility in shaping optical properties and designing cutting-edge devices. Quasi-one-dimensional Ta2NiS5, with giant optical anisotropy, has been used in the development of new lasers and sensors. In this research endeavor, we successfully acquired the complete dielectric tensor of Ta2NiS5, utilizing the advanced technique of Mueller matrix spectroscopic ellipsometry, enabling a rigorous quantitative assessment of its optical anisotropy. The results indicate that Ta2NiS5 demonstrates giant birefringence and dichroism, with Δnmax = 1.54 and Δkmax = 1.80. This pursuit also delves into the fundamental underpinnings of this optical anisotropy, drawing upon a fusion of first-principles calculations and critical points analysis. The anisotropy of Ta2NiS5 arises from differences in optical transitions in different directions and is shown to be due to van Hove singularities without exciton effects. Its giant optical anisotropy is expected to be useful in the design of novel optical devices, and the revelation of the physical mechanism facilitates the modulation of its optical properties. [ABSTRACT FROM AUTHOR]

The following review is Part III of a series concerned with the direct hydrometallurgical processing of nickel sulfide flotation concentrates. In the first part of this series, piloted leaching processes and commercial nickel sulfide operations that employed direct hydrometallurgical processing were comprehensively reviewed. In the second part of this series, laboratory investigations into pressure leaching of nickel sulfide concentrates were critically analyzed. In Part III of this series, laboratory investigations into the leaching of nickeliferous sulfide concentrates at ambient pressure are reviewed, and the challenges and research opportunities in the direct leaching of nickel sulfide flotation concentrates are summarized. The majority of the published studies on atmospheric leaching of nickel sulfide flotation concentrates have focused on leaching in chloride media due to the faster leaching kinetics in chloride lixiviants relative to sulfate media; bioleaching due to the perceived environmental advantages over other leaching systems; and pyrometallurgical pre-treatments to render refractory sulfide minerals more amenable to subsequent leaching. [ABSTRACT FROM AUTHOR]

Herein, new efficient photocatalysts composed of Cu doped NiS/ZnS quantum dots-composites were synthesized by coprecipitation technique for treatment of organic dyes. Treatment of dyeing-wastewater is an important issue to reduce the environmental pollution and providing a large quantity of pure water. The transmission electron microscope images of pure and Cu doped NiS/ZnS composites show quantum dots particles with size of 3–4 nm. The X-ray diffraction confirmed the formation of cubic ZnS and rhombohedral NiS. Optically, doping by 4 wt% Cu ions was reduced the band gap energy of ZnS from 3.4 to 2.98 eV, which improve the visible light absorption. 4 wt% Cu doped NiS/ZnS nanocomposite reveals a fast and remarkable photodegradation efficiency of 95%, 98% and 97% towards 20 ppm methyl green, methylene blue and Congo red during 60 min of sunlight irradiation. For three cycles, 4 wt% Cu doped NiS/ZnS nanocomposite exhibits significant photodegradation activities of 98%, 92% and 85%, respectively. The improvements of the photocatalytic activity of Cu doped NiS/ZnS nanocomposite can be attributed to some factors including visible-light absorption and charge carriers separation. The Cu doping improves the visible light response of ZnS through reducing the band gap which reinforce the number of the excited electron-hole pairs. Too, Cu ions act as trapping centers (Cu2+ + e → Cu+) which boost the separation of the excited electron-hole pairs and consequently improve the photodegradation activity. This study point out that the integration of p-n heterostructure and doping strategies are efficient for deign of photocatalysts for wastewater treatment. [ABSTRACT FROM AUTHOR]

Van der Waals (vdW) interfaces can be formed via layer stacking regardless of the lattice constant or symmetry of the individual building blocks. Herein, we constructed a vdW interface of layered Ta2NiS5 and CrOCl, which exhibited remarkably enhanced in-plane anisotropy via polarized Raman spectroscopy and electrical transport measurements. Compared with pristine Ta2NiS5, the anisotropy ratio of the Raman intensities for the B2g, 2Ag, and 3Ag modes increased in the heterostructure. More importantly, the anisotropy ratios of conductivity and mobility in the heterostructure increased by one order of magnitude. Specifically speaking, the conductivity ratio changed from ~2.1 (Ta2NiS5) to ~15 (Ta2NiS5/CrOCl), while the mobility ratio changed from ~2.7 (Ta2NiS5) to ~32 (Ta2NiS5/CrOCl). Such prominent enhancement may be attributed to the symmetry reduction caused by lattice mismatch at the heterostructure interface and the introduction of strain into the Ta2NiS5. Our research provides a new perspective for enhancing artificial anisotropy physics and offers feasible guidance for future functionalized electronic devices. [ABSTRACT FROM AUTHOR]

Microscopic compartmentalization is beneficial in synthetic chemistry and indispensable for the evolution of life to separate a reactive "inside" from a hydrolyzing "outside". Here, we show compartmentalization in aqueous solution containing mixtures of fatty acids up to 19 carbon atoms which were synthesized by one-pot reactions of acetylene and carbon monoxide in contact with nickel sulfide at 105 °C, reaction requirements which are compatible to Hadean Early Earth conditions. Based on confocal, dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements, vesicle-like structures with diameters of 10–150 nm are formed after solvent extraction and resolubilisation. Moreover fluorescent dye was encapsulated into the structures proving their vesicular properties. This self-assembly could also have occurred on Early Earth as a crucial step in establishing simple membranes of proto-cells as a prerequisite in the evolution of metabolism and life. [ABSTRACT FROM AUTHOR]

A new method has been proposed for the synthesis of bis(phosphine sulfides) and nickel and platinum chelate complexes of 1,3,6-azadiphosphacycloheptanes. The method is based on the ability of 14-membered 3,6,10,13-diazadiphosphacyclotetradecanes to undergo a reversible transformation in solutions into a mixture of meso- and rac-isomers of seven-membered bis-phosphines. The reaction of 3,6,10,13-diazadiphosphacyclotetradecanes with elementary sulfur results in 14-membered tetrakis(phosphine sulfides) or seven-membered bis(phosphine sulfides), depending on the reaction conditions. The reaction of 1,3,6-azadiphosphacycloheptanes, resulting from the reversible dissociation of 14-membered tetraphosphines in chloroform, with Ni(CH3CN)6(BF4)2 and Pt(COD)Cl2 gives the corresponding chelate complexes. The structures of the meso-isomer of 1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane-3,6-disulfide, bis-(κ2-1-isopropyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)nickel bis(tetrafluoroborate), bis-(κ2-1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)chloronickel tetrafluoroborate, and cis-dichloro-(κ2-1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)platinum(II), isolated in crystalline form, have been confirmed by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]