Iron-nickel Sulfide Research Articles

Design and Optimization of MoS2@rGO@NiFeS Nanocomposites for Hybrid Supercapattery Performance and Sensitive Electrochemical Detection.

Metal sulfide-based composites have become increasingly common as materials used for electrodes in supercapacitors because of their excellent conductivity, electrochemical activity, and redox capacity. This study synthesized a composite of NiFeS@MoS2@rGO nanostructure using a simple hydrothermal approach. The synthesized nanocomposite consisted of the composite of nickel sulfide and iron sulfide doped with MoS2@rGO. A three-electrode cell is employed to investigate the electrochemical properties of the NiFeS@MoS2@rGO electrode. The results demonstrated an optimal specific capacitance of 3188 F/g at 1.4 A/g in a 1 M KOH electrolyte. Furthermore, a supercapattery is designed utilizing NiFeS@MoS2@rGO//AC as the positive electrode and activated carbon (AC) as the negative electrode materials. The resulting supercapattery is designed at a cell voltage of 1.6 V, achieving a specific capacity value of 189 C/g at 1.4 A/g. It also demonstrated an excellent energy density of 55 Wh/kg with an enhanced power density of 3800 W/kg. Furthermore, the hybrid device demonstrated remarkable stability with a cycling stability of 95% over 30,000 charge-discharge cycles at a current density of 1.4 A/g. The supercapattery, which has excellent energy storage capabilities, is used as a power source for operating different portable electronic devices.

Corrosion Evaluation and Mechanism Research of AISI 8630 Steel in Offshore Oil and Gas Environments.

In this study, we optimized the traditional composition of AISI 8630 steel and evaluated its corrosion resistance through a series of tests. We conducted corrosion tests in a 3.5% NaCl solution and performed a 720 h fixed-load tensile test in accordance with the NACE TM-0177-2016 standard to assess sulfide stress corrosion cracking (SSCC). To analyze the corrosion products and the structure of the corrosion film, we employed X-ray diffraction and transmission electron microscopy. The corrosion rate, characteristics of the corrosion products, structure of the corrosion film, and corrosion resistance mechanism of the material were investigated. The results indicate that the optimized AISI 8630 material demonstrates excellent corrosion resistance. After 720 h of exposure, the primary corrosion products were identified as chromium oxide, copper sulfide, iron oxide, and iron-nickel sulfide. The corrosion film exhibited a three-layer structure: the innermost layer with a thickness of 200-300 nm contained higher concentrations of alloying elements and formed a dense, cohesive rust layer that hindered the diffusion of oxygen and chloride ions, thus enhancing corrosion resistance. The middle layer was thicker and less rich in alloying elements, while the outer layer, approximately 300-400 nm thick, was relatively loose.

Surface oxygen-doping induced atom migration of iron-nickel sulfides with tailored d-band center for enhanced oxygen evolution

The rational design of tailored surface properties by surface doping is an efficient yet challenging method for enhanced OER performance. Herein, we propose atom migration effect, induced by surface O-doping to precisely control surface compositions of FeNiS2 (FNS). The FNS undergoes a surface sulfur/oxygen exchange to form FeNiS2-xOx (FNSO) structure after surface O-doping, while the bulk phases remain unchanged. In contrast, the surface Ni/Fe ratio is significantly increased due to the accelerated atom migration of nickel during surface O-doping. At elevated temperatures, the bulk phase is prone to transition into complex phases of FeNiS and FeNiO, leading to the decreased surface Ni/Fe ratio. The optimized FNSO demonstrates superior OER performance with a low overpotential of 256 mV at 100 mA cm−2, and the assembled anion exchange membrane water electrolyzer requires only 1.83 V at 1 A cm−2 with robust durability. Theoretical calculations reveal that this surface atom migration adjusts the d-band center level, optimizes surface adsorption/desorption behaviors, and expedites the OER kinetics. This work contributes to a deeper comprehension of surface modulation with desired surface properties of sulfides and other compounds for enhanced OER performance.

Self-supported bimetallic iron-nickel sulfide nanosheets for efficient alkaline electrocatalytic oxygen evolution

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 (Fe1-xS-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.

FeNi2S4-A Potent Bifunctional Efficient Electrocatalyst for the Overall Electrochemical Water Splitting in Alkaline Electrolyte.

For a carbon-neutral society, the production of hydrogen as a clean fuel through water electrolysis is currently of great interest. Since water electrolysis is a laborious energetic reaction, it requires high energy to maintain efficient and sustainable production of hydrogen. Catalytic electrodes can reduce the required energy and minimize production costs. In this context, herein, a bifunctional electrocatalyst made from iron nickel sulfide (FeNi2S4 [FNS]) for the overall electrochemical water splitting is introduced. Compared to Fe2NiO4 (FNO), FNS shows a significantly improved performance toward both OER and HER in alkaline electrolytes. At the same time, the FNS electrode exhibits high activity toward the overall electrochemical water splitting, achieving a current density of 10mAcm-2 at 1.63V, which is favourable compared to previously published nonprecious electrocatalysts for overall water splitting. The long-term chronopotentiometry test reveals an activation followed by a subsequent stable overall cell potential at around 2.12V for 20h at 100mAcm-2.

Comparative study on prussian blue analogue derived iron nickel oxide, sulfide and phosphide as electrode materials for supercapacitors

Over the past decades, although metal oxides, sulfides and phosphides have developed as materials for supercapacitors (SCs), their SCs` performance should be deeply studied. In this work, FeNi-Prussian blue analogue (FeNi-PBA) was prepared via a simple co-precipitation method and served as a sacrificial template to prepare iron nickel oxide (NiFe2O4), sulfides (FeS/NiS2) and phosphides (Fe2P/Ni2P), whose capabilities for SCs were compared, respectively. The electrochemical results confirmed that the specific capacitance of FeS/NiS2 was 490.6 F g−1 much higher than those of NiFe2O4 (86 F g−1) and Fe2P/Ni2P (174.6 F g−1) at the current density of 1 A g−1. Therefore, the FeNiSx delivered the best electrochemical properties among them, because FeS/NiS2 composed by FeS/NiS2 heterostructure with sulfur vacancies provided an intimate/compact interfacial arrangement which better synergized the polyatomic conductivity and a large number of redox-active sites to bring about excellent electrochemical performance. Furthermore, FeS/NiS2 and activated carbon (AC) were employed to fabricate an asymmetric supercapacitor (ASC), which achieved the energy density of 54.34 Wh·kg−1 and the power density of 1349.13 W·kg−1, and could power a commercial light-emitting diode light. Among FeNiOx, FeS/NiS2 and Fe2P/Ni2P, FeS/NiS2 can be a potential electrode material for SCs attributing to its heterostructure and sulfur vacancies favourable for multi-atom conductivity and numerous redox-active sites. This work evidences that metal sulfides deliver the superior SCs` performance than the corresponding metal oxides and phosphides.

S-vacancy-rich NiFe-S nanosheets based on a fully electrochemical strategy for large-scale and quasi-industrial OER catalysts

The oxygen evolution reaction (OER) is regarded as a critical component in the water splitting system. Creating vacancies, increasing active surface area, and optimizing electronic structure would improve electrocatalytic performance. Herein, a facile electrochemical reduction method is used to generate sulfur vacancies in nickel iron sulfide (NiFe-S) with a large geometry area of 15 × 16 cm2, which is synthesized using an electrodeposition process assisted with the ion exchange (IOE) method. The X-ray absorption spectroscopies (XAS) are applied for atomic-level structural analysis, verifying that electrochemical desulfurization generates abundant S vacancies. The NiFe-S with abundant sulfur vacancies (NiFe-S-Vs) exhibits a low overpotential (252 mV at 100 mA cm−2), and long stability for 260 h at 500 mA cm−2. More importantly, the NiFe-S-Vs catalyst also delivers a small overpotential (235 mV at 1000 mA cm−2) and high alkaline tolerance (140 h at 500 mA cm−2) in 6 M KOH at 60 °C), implying a potentially significant industrial application prospect. Finally, theory calculation further illustrates the high performance of as-prepared vacancies-rich catalyst.

Unlocking enhanced electrochemical performance through oxygen–nitrogen dual functionalization of iron–nickel–sulfide for efficient energy storage systems

This study showcases a supercapacitor device with oxygen–nitrogen dual functionalized and sulfurized iron–nickel hydroxysulfide, demonstrating high performance and stability for energy storage.

Construction of nickel iron sulfide at ambient temperature on Fe foam for high-current overall water splitting

The development of non-precious metal overall water splitting electrocatalysts under high current density is of utmost importance in feasible water splitting technology.

Incorporation of Bimetallic Sulfide with Carbon Nitride for Advanced Na-Ion Batteries.

Sodium-ion batteries (SIBs) have received tremendous attention owing to their low cost, high working voltages, and energy density. However, the design and development of highly efficient SIBs represent a great challenge. Here, a unique and reliable approach is reported to prepare carbon nitride (CN) hybridized with nickel iron sulfide (NFCN) using simple reaction between Ni-Fe layered double hydroxide and dithiooxamide. The characterization results demonstrate that the hybridization with optimal amount of CN induces local distortion in the crystal structure of the hybrid, which would benefit SIB performance. Systematic electrochemical studies with a half-cell configuration show that the present hybrid structure exhibits a promising reversible specific capacity of 348 mAh g-1 at 0.1 A g-1 after 100 cycles with good rate capability. Simulation result reveals that the iron atoms in nickel iron sulfide act as a primary active site to accommodate Na+ ions. At last, with a full cell configuration using NFCN and Na3V2(PO4)2O2F as the anode and cathode, respectively, the specific capacity appears to be ≈95 mAh g-1 after 50 cycles at 0.1 A g-1 condition. This excellent performance of these hybrids can be attributed to the synergistic effect of the incorporated CN species and the high conductivity of nickel-iron sulfide.

Enhanced structural properties of electrochemically synthesised NiFeS using 500 keV carbon C++ ions irradiation

ABSTRACT An electrochemical approach was used to synthesise nickel iron sulphide (NiFeS) materials in this work. The prepared NiFeS underwent a thorough investigation, which included analyses of its optical, electrical, structural, morphological, elemental, and functional group properties. Cubic crystal formations with prominent peaks were visible from the structural pattern. Nanoflakes and pebbles were visible, and their elements were determined through elemental dispersive X-ray diffractometer (EDX) spectrum. The film’s crystallinity increased after incorporating carbon ions and its optical properties improved, with energy band gap values ranging from 1.50 eV to 1.15 eV as the peaks became more distinct. The materials produced could be utilised in the production of solar cells and optoelectronic devices. The electrical conductivity diminishes with increasing thickness. Carbon ion radiation increases carrier concentration, which increases electrical conductivity.

Bimetallic nickel iron sulfide directly grown on defect-rich Ti3C2 MXene as an efficient bifunctional electrocatalyst for water electrolysis

Water electrolysis has been regarded as ideal method for producing high-purity hydrogen without the generation of environmental pollutants. Accordingly, the development of precious metal-free electrocatalysts that demonstrate high activity for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) is essential for practical water electrolysis. Herein, porosity-engineered Ti3C2 MXene is employed as an efficient substrate for a bimetallic Ni-Fe-S electrocatalyst. The porous and defect-rich Ti3C2 (D-Ti3C2) flakes provide metal-like electrical conductivity and large surface area for direct growth of active species. Simultaneously, the Ni-Fe-S nanoparticles, constructed through a strong coupling between NiS2 and (Ni,Fe)S2 solid solution, not only serve as active sites with rich redox properties, but also generate charge transfer channels for electrochemical reactions. Leveraging these advantageous properties, the resulting Ni-Fe-S/D-Ti3C2 electrocatalyst exhibits excellent bifunctional electrocatalytic performance toward both OER and HER. As a result, the symmetric water electrolysis cell using the Ni-Fe-S/D-Ti3C2 requires a low cell voltage of 1.621 V to deliver current density of 10 mA cm−2, and shows stable electrocatalytic performance over 100 h of continuous operation.

One-step electrodeposition synthesis of bimetallic sulfides for highly efficient electrocatalytic water splitting

Investigation of highly effective and affordable metal-based electrocatalysts is crucial for water splitting that yields pure hydrogen. Herein, using one-step room-temperature electrodeposition, we successfully created a binary metal nickel-iron sulfide bifunctional electrocatalyst having plenty of active sites and a significant specific surface area on nickel foam (NF). Additionally, the synergistic interaction of the two metal components, iron and nickel, facilitates the electron transfer process and increases the materials’ electrocatalytic performance. To obtain 10 mA cm−2, the catalyst only requires 75 mV for HER and 210 mV for OER in 1.0 M KOH. The two-electrode electrolyzer only needs a modest driving voltage (1.46 V@10 mA cm−2). The research presented here offers fresh understandings into the water splitting of nickel-iron-based sulfides as well as a reasonable direction for the development of bifunctional electrocatalysts.

Nickel-iron sulfide nanoparticles supported on biomass-derived N-doped hierarchical porous carbon as a robust electrode for supercapacitors

Biomass-based carbon electrode material with hierarchical porous structure is considered as a promising candidate for supercapacitor applications, which could enhance the electron transfer and shorten the ion diffusion pathways. However, the low energy density of carbon-based materials seriously affects their wide applications. Herein, 3D N-doped hierarchical porous carbon coupled with nickel-iron sulfide nanoparticles (Fe5Ni4S8/FeS@N-HPC) is fabricated by a simple pyrolysis process. The 3D N-doped interconnected porous structure with large specific surface area provides more channels for ion transport and electron transfer. The nickel-iron sulfide nanoparticles in the porous carbon offer numerous sites for reduction and oxidation occurring to improve the charge storage for supercapacitors. Consequently, the synthesized Fe5Ni4S8/FeS@N-HPC electrode exhibits excellent electrochemical properties. The optimized Fe5Ni4S8/FeS@N-HPC composite fabricated under 800 °C displays an excellent capacitance of 2812.4 F g−1 (734.56 C g−1) at a current density of 0.5 A g−1. Beside, the Fe5Ni4S8/FeS@N-HPC-800//active carbon asymmetric supercapacitor shows an energy density of 76.8 W h kg−1 at a power density of 395.03 W kg−1 and superior cycling stability of 93.24% over 10,000 charge-discharge cycles. Our work presents a novel approach to the construction of high-performance electrode materials for supercapacitors.

Synergistically induced dual-interfacial interactions in iron-nickel sulfides heterojunction encapsulated by N, S-codoped carbon matrix heightened ion-transport kinetics for sodium-storage

Exploring bimetallic sulfides of diverse metal species with well-defined nanoarchitectures and distinctive interfacial interactions is indispensable for advanced sodium-storage systems in achieving rapid electron/ion transfer kinetics, optimizing structural durability, and enhancing electrochemical energy storage. In this regard, the fabrication of a spindle-like hierarchical hollow nanocage with the dual heterointerfaces was reported utilizing N, S co-doped carbon support encapsulating hollow FeS2/NiS heterojunction (FeS2/NiS@N,S-C) through the critical steps of facile dopamine self-polymerization, followed by hydrolyzation, carbonization and further sulphuration. Benefiting from the great superiorities of superior conductivity, excellent structural robustness, abundant active reaction sites, efficient charge transport pathways, as well as fast ion-migration kinetics bestowed by creating an synergistically induced dual interfacial interaction in the ingenious nanoarchitecture, the FeS2/NiS@N,S-C composites render a significantly optimized comprehensive performance of Na+-storage, yielding a highly competitive capacity of 598.0 mAh g−1 after 600 cycles at 1.0 A g−1, and desirable cycle stability with supernormal rate capability (362.6 mAh g−1 after 1950 cycles at 20.0 A g−1), one of the best performances for FeS2- or NiS based heterojunctions. Meanwhile, the redox mechanism involving initial intercalation reaction and following conversion stage was uncovered detailly by a set of ex-situ experimental characterizations. Theoretical evidences drawn from density functional theory calculations illustrate that the formation of dual heterointerfaces in FeS2/NiS@N,S-C composites enables good conductivity, optimizes Na+ adsorption energy, and reduces activation energy for Na+ migration, which facilitates ion/electron migration and enhances reaction kinetics of the electrode.

Heterogeneous engineering of nickel-iron sulfide with cerium-promoted reconstruction for enhanced oxygen evolution

The development of efficient oxygen evolution reaction (OER) electrocatalysts is critical for electrochemical water splitting. Herein, a cerium-doped Ni3S2/NiS/FeS heterogeneous structure nanoparticle supported on nickel foam (Ce-NiSx/FeS/NF) is prepared as a precatalyst for OER reaction in alkaline solution. The heterointerfaces of NiSx/FeS adjust the electronic structure and expose more active sites, accelerating the OER process. The Ce incorporation promotes the in situ reconstruction and oxidation of the sulfides to the heterogeneous NiOOH/FeOOH, which act as the actual active sites for the OER reaction. Thus, the Ce-NiSx/FeS/NF demonstrates excellent OER performance with a low overpotential of 125 mV at 10 mA cm−2 and long-term robustness. Additionally, a water splitting device is constructed using Ce-NiSx/FeS/NF and commercial Pt/C/NF as the anode and cathode, respectively. This device achieves a current density of 10 mA cm−2 at 1.38 V with 50 h of reliable continuous operation at 1.78 V. Density functional theory (DFT) calculation confirms that the active sites of Ce-NiOOH/FeOOH optimize intermediates adsorption energy (higher OH− adsorption energy and lower O2 desorption energy) and provide faster OER kinetics, conducive to the OER process. This work presents the concept of rare-earth-doping promotes reconstruction of heterogeneous transition-metal-based compounds for the development of high-performing OER electrocatalysts.

Iron Nickel Sulfide Nanorods for Oxygen and Hydrogen Evolution Reaction

AbstractThe electrochemical water splitting process needs fabrication of cost‐effective transition metal‐based materials for its commercialization process. Transition metal chalcogenides are good electrocatalysts for such processes in different media. Herein, we have synthesized Iron Nickel Sulfide (FeNiS2) nanorods by one step hydrothermal method. The synthesized material performed excellent bifunctional activity i. e. Hydrogen Evolution Reaction (HER) & Oxygen Evolution Reaction (OER) in basic environment. The nanorod shaped FeNiS2 deliver its OER activity at an overpotential of 250 mV to afford current density 10 mA cm−2. It shows low Tafel slope of 99 mV/dec along with 11 h stability. Further, we have tested HER activity and the as‐prepared material shows a good overpotential of 141 mV at 10 mA cm−2 and low Tafel slope of 104 mV/dec with durability of 9 h. The electrochemical characterization suggests that FeNiS2 nanorod could be an efficient, OER and HER electrocatalyst for water splitting reaction.

Peony-like CuxSy hybrid iron-nickel sulfide heterogeneous catalyst for boosting alkaline oxygen evolution reaction

Designing and fabricating earth-abundant and highly-efficient electrocatalysts is vital to accelerate dynamics of the oxygen evolution reaction (OER), which is a half reaction of water splitting. In the present work, we developed and successfully synthesized copper sulfides with diverse valence states hybridizing iron-nickel sulfide (CuxSy/FeNiS) heterogeneous catalyst via a governable two-step hydrothermal method, which processes superior OER performance and outstanding durableness in 1.0 M KOH solution. Benefitting from the polyvalent copper dopant and competent interfacial effects between Cu sulfides and FeNiS, this self-supported hybrid material requires 286 and 354 mV to achieve 50 and 500 mA cm−2, respectively. Besides, the plentiful disordered structures in CuxSy/FeNiS hybridization also enrich the exposure sites and modulate the electronic interaction of active sites and enhance the intrinsic OER activity. Furthermore, this optimal CuxSy/FeNiS electrode exhibits remarkable stability at both 10 and 100 mA cm−2 prolonged chronopotentiometry process.

Iron nickel sulphide embedded on multi-walled carbon nanotubes as efficient electrocatalysts for oxygen evolution reaction in alkaline medium

Oxygen evolution reaction (OER) plays a vital role in clean energy production such as water splitting and metal-air batteries to achieve renewable energy technologies. In this regard, electrocatalysts play a major role in the oxidative half-cell reaction of water splitting. Among various transition metal-based catalysts, FeNi-based electrocatalysts are of particular interest owing to their low-cost, non-toxic, non-precious metal, high stability, and enhanced electrocatalytic performance of OER. Herein, we report the preparation of iron-nickel sulphide-based catalysts (a mixed phase of Fe5Ni4S8 and Ni9S8, or FeNiS) and their composite with MWCNTs using a facile hydrothermal method for electrocatalytic water oxidation. The physicochemical properties of the prepared composite of FeNiS-MWCNT were analyzed through various characterization techniques. The FeNiS-MWCNT composite exhibits enhanced electrochemical performance of OER with the current density of 10 mA cm−2 at a lower overpotential of 260 mV vs RHE and lower Tafel slope of 50 mV dec−1 as compared to FeNiS (10 mA cm−2 at an overpotential of 370 mV vs RHE; Tafel slope of 82 mV dec−1). The superior electrocatalytic performance of the FeNiS-MWCNT composite over the FeNiS catalyst is attributed to the higher surface area, conductivity of the MWCNT and the synergistic effect of FeNiS and MWCNTs. This work also paves the way for the development of highly efficient and promising non-precious metal catalysts for electrocatalytic water oxidation as an alternative to traditional noble-metal catalysts.

High-efficiency overall alkaline seawater splitting: using a nickel–iron sulfide nanosheet array as a bifunctional electrocatalyst

NiFeS nanosheet array on Ni foam (NiFeS/NF) behaves as a superb bifunctional electrocatalyst for overall seawater splitting, attaining a commercially demanded current density of 500 mA cm−2at a low cell voltage of 1.85 V with robust stability.