Iron-nickel Sulfide Research Articles

Bimetallic Sulfides Embedded in a Boron Modulated Carbon Matrix as the Bifunctional Catalyst with a Low Oxygen Evolution Reaction Overpotential for an Advanced Zinc-Air Battery

A composite bifunctional catalyst (FeNiS-NBC/C) was prepared with iron nickel sulfide nanoparticles embedded in a hybrid carbon matrix. The unique introduction of the boron element modulated the structure in achieving an ultralow oxygen evolution reaction (OER) overpotential. The incorporation of cellulose in the synthesis has improved the oxygen reduction reaction (ORR) performance. In the two-step synthesized FeNiS-NBC/C, a mixed transport network formed, with enhanced heterostructures and abundant catalytic sites. FeNiS-NBC/C exhibits the OER overpotential of 216 mV at the current density of 10 mA cm–2, as well as with the excellent ORR performance. The low OER overpotential reduces the oxidation corrosion in the rechargeable zinc-air batteries. The zinc-air battery with a liquid electrolyte assembled using FeNiS-NBC/C exhibited the power density of 133.0 mW cm–2 and specific capacity of 797.8 mAh g–1. The solid-state zinc-air battery assembled using FeNiS-NBC/C exhibited the power density of 61.4 mW cm–2 and can be stably charge–discharge cycled for 46 h. This work pointed out a novel avenue to construct bifunctional catalysts in the future for advanced zinc-air batteries.

Electrodeposited amorphous nickel–iron phosphide and sulfide derived films for electrocatalytic oxygen evolution

The preparation of inexpensive and efficient electrocatalysts for oxygen evolution reaction (OER) is crucial in the widespread application of water electrolyzers. A simple one-step aqueous electrodeposition method is utilized to prepare amorphous nickel-iron sulfide (Ni–Fe–S) and phosphide (Ni–Fe–P) films on Ni foam. The deposited films are highly porous, and can convert to active electrocatalysts for OER. In 1 M KOH, the Ni–Fe–S shows the highest OER activity, and requires only 230 mV overpotential to reach 0.05 A cm−2 OER current densities. The Fe–Ni–S also sustains the 30 h 0.05 A cm−2 galvanostatic OER test. Ex-situ characterizations show that sulfur in the Fe–Ni–S is oxidized and leached into the solution during OER, and that (oxy)hydroxide layer is formed at the surface. The adsorption energy of the hydroxyl group, an OER intermediate, is tuned by the electron interaction between the Ni and Fe, and the Ni–Fe–S exhibits the optimum hydroxyl group adsorption energy and the most facile OER kinetics. Also, higher intrinsic OER activity is observed for the electrodeposited amorphous nickel phosphide-derived film than the amorphous nickel sulfide-derived film.

Effect of the interfacial electronic coupling of nickel-iron sulfide nanosheets with layer Ti3C2 MXenes as efficient bifunctional electrocatalysts for anion-exchange membrane water electrolysis

In this study, nickel-iron sulfide (NiFeS) nanosheets were immobilized on Ti3C2 MXene-decorated nickel foam (Ti3C2 MXene/NF) by hydrothermal reaction (NiFeS@Ti3C2 MXene/NF). The morphology of NiFeS and interactions with Ti3C2 MXene resulted in electronic coupling that optimized the adsorption energies of water, protons, and oxygen atom for the HER (180 mV@20 mA cm-2) and OER (290 mV@20 mA cm-2). The NiFeS@Ti3C2 MXene/NF catalyst showed good water splitting performance in an alkaline membrane water electrolyzer, yielding a current density (j) of 401 mA cm-2 at 1.85 V with 67.65 % cell efficiency, performance comparable to Pt/C||RuO2 cells. From a commercial point of view, our electrolyzers are the best because of their low loading of catalysts (ca. 1.25 mg cm-2) and low operating temperatures (50 °C), resulting in low capital and operating costs. Our findings will aid the development of commercial green hydrogen production and offers an alternative to PEMWE.

Enhanced Cr(VI) removal induced by electron donor in magnetic iron-nickel sulfides biochar composites

In this study, magnetic iron-nickel sulfides biochar composites (MINBs) were successfully prepared via one-step solvothermal method and applied to Cr(VI)-containing wastewater treatment. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that synthesized iron-nickel sulfides anchored and dispersed on biochar surface. Cr(VI) removal efficiency and capacity by MINB-5 (molar ratio of Ni to Fe was 5%) were more than 97% and 24.8 mg g-1 within 20 min respectively, when the initial concentration of Cr(VI) was 20 mg L-1. Effects of different operational parameters on Cr(VI) removal efficiency were investigated, including molar ratio of Ni to Fe, dosage of catalyst, initial concentration of Cr(VI), pH value of solution, coexisting ions, natural organic matters (NOMs) and temperature. X-ray photoelectron spectroscopy (XPS) and flame atomic absorption spectrometric (FAAS) analysis demonstrated that Cr(VI) was removed through reduction process by Fe(Ⅱ), which was released from MINBs. Persistent free radicals (PFRs) of biochar, Ni(Ⅱ) and S(-Ⅱ) in MINBs jointly accelerated Fe(Ⅱ)/Fe(III) circulation, instead of direct reduction of Cr(VI) directly. These novel findings provide a new prospect of application of magnetic iron-nickel sulfides biochar composites for Cr(VI)-polluted wastewater remediation.

S/Se dual-doping promotes the formation of active Ni/Fe oxyhydroxide for oxygen evolution reaction of (sea)water splitting

Surface reconstruction produces metal oxyhydroxide (∗OOH) active sites, and promoting surface reconstruction is essential for the design of OER electrocatalysts. In this paper, we reported that a large amount of active NiFeOOH was generated in-situ on the surface of nickel-iron sulfide selenide, thus exposing more active sites and efficiently catalyzing OER. In 1 M KOH solution, NiFeOOH(S,Se) achieves an ultra-low overpotential of 195 mV at the current density of 10 mA cm−2, and the Tafel slope is only 31.99 mV dec−1, showing excellent catalytic performance. When the current density is 100 mA cm−2, the over-potential of NiFeOOH(S,Se) in KOH + seawater solution is 239 mV, which is almost equivalent to 231 mV in KOH solution. The excellent OER stability of the NiFeOOH(S,Se) catalyst in alkaline electrolytes was confirmed, and the overpotential did not change significantly after 4 days of testing in KOH + seawater solution.

Coordination modulation of iridium single-atom catalyst maximizing water oxidation activity

Single-atom catalysts (SACs) have attracted tremendous research interests in various energy-related fields because of their high activity, selectivity and 100% atom utilization. However, it is still a challenge to enhance the intrinsic and specific activity of SACs. Herein, we present an approach to fabricate a high surface distribution density of iridium (Ir) SAC on nickel-iron sulfide nanosheet arrays substrate (Ir1/NFS), which delivers a high water oxidation activity. The Ir1/NFS catalyst offers a low overpotential of ~170 mV at a current density of 10 mA cm−2 and a high turnover frequency of 9.85 s−1 at an overpotential of 300 mV in 1.0 M KOH solution. At the same time, the Ir1/NFS catalyst exhibits a high stability performance, reaching a lifespan up to 350 hours at a current density of 100 mA cm−2. First-principles calculations reveal that the electronic structures of Ir atoms are significantly regulated by the sulfide substrate, endowing an energetically favorable reaction pathway. This work represents a promising strategy to fabricate high surface distribution density single-atom catalysts with high activity and durability for electrochemical water splitting.

Surface Self-Reconstruction of Iron Nickel Sulfides on Ni Foam During Oxygen Evolution Reaction

Surface Self-Reconstruction of Iron Nickel Sulfides on Ni Foam During Oxygen Evolution Reaction

Plasma-assisted rhodium incorporation in nickel–iron sulfide nanosheets: enhanced catalytic activity and the Janus mechanism for overall water splitting

Rh was incorporated in Fe-doped Ni3S2 nanosheets with the assistance of hydrogen plasma to significantly enhance the HER/OER catalytic activity. The operando evolution behavior and Janus catalytic mechanism of this catalyst were further revealed.

Ultrathin NiFeS nanosheets as highly active electrocatalysts for oxygen evolution reaction

The development of efficient and cost-effective oxygen evolution reaction (OER) electrocatalysts is crucial for clean energy conversion and storage devices, such as water-splitting, CO2 reduction, and metal-air batteries. Herein, we report an efficient 2-dimensional OER catalyst of ultrathin nickel-iron sulfide nanosheets (NiFeS-NS). Dodecanethiol is employed in the synthesis, which prohibits the growth along the Z-axis, thus a nanosheet is obtained. The NiFeS-NS shows high OER catalytic activity, which only requires a small overpotential of 273 mV to achieve the OER current density of 10 mA/cm2 in alkaline electrolyte, and almost no decay after 150 h of chronopotentiometry test. The high performance is attributed to the 2-dimensional structure, the synergistic effect from the Ni and Fe components which promotes the formation of the high valence Ni species, and the tuning effect from the in-situ generated sulfate doping. This work demonstrates the advantages of the 2-dimensional sulfides in electrocatalysis.

Reversible Electron Transfer and Substrate Binding Support [NiFe3S4] Ferredoxin as a Protein-Based Model for [NiFe] Carbon Monoxide Dehydrogenase.

The nickel-iron carbon monoxide dehydrogenase (CODH) enzyme catalyzes the reversible and selective interconversion of carbon dioxide (CO2) to carbon monoxide (CO) with high rates and negligible overpotential. Despite decades of research, many questions remain about this complex metalloenzyme system. A simplified model enzyme could provide substantial insight into biological carbon cycling. Here, we demonstrate reversible electron transfer and binding of both CO and cyanide, a substrate and an inhibitor of CODH, respectively, in a Pyrococcus furiosus (Pf) ferredoxin (Fd) protein that has been reconstituted with a nickel-iron sulfide cluster ([NiFe3S4] Fd). The [NiFe3S4] cluster mimics the core of the native CODH active site and thus serves as a protein-based structural model of the CODH subsite. Notably, despite binding cyanide, no CO binding is observed for the physiological [Fe4S4] clusters in Pf Fd, providing chemical rationale underlying the evolution of a site-differentiated cluster for substrate conversion in native CODH. The demonstration of a substrate-binding metalloprotein model of CODH sets the stage for high-resolution spectroscopic and mechanistic studies correlating the subsite structure and function, ultimately guiding the design of anthropogenic catalysts that harness the advantages of CODH for effective CO2 reduction.

Insight into sulfur and iron effect of binary nickel-iron sulfide on oxygen evolution reaction

Insight into sulfur and iron effect of binary nickel-iron sulfide on oxygen evolution reaction

A multidimensional rational design of nickel–iron sulfide and carbon nanotubes on diatomite via synergistic modulation strategy for supercapacitors

Based on their characteristics, transition metal layered double hydroxides have been of great scientific interest for their use in supercapacitors. Up until now, severe aggregation and low intrinsic conductivity have been the major hurdles for their application. In this work, nickel–iron sulfide nanosheets (NiFeSx) and carbon nanotubes (CNTs) were synthesized on diatomite using chemical vapor deposition and a two-step hydrothermal method to overcome these challenges. Synthesis of this composite successfully exploits the synergistic effect of multicomponent materials to improve the electrochemical performance. Diatomite is selected as a substrate to provide preferable surroundings for the uniform dispersion of nanomaterial on its surface, which enlarges the active sites that come in contact with the electrolytes, significantly improving the electrochemical properties. Combined with high conductivity and a synchronous sulfurization effect, the NiFeSx@CNTs@MnS@Diatomite electrode delivered a high specific capacitance of 552F g−1 at a current density of 1 A g−1, a good rate capability of 68.4% retention at 10 A g−1, and superior cycling stability of 89.8% capacitance retention after 5000 cycles at 5 A g−1. Furthermore, an asymmetric supercapacitor assembled via NiFeSx@CNTs@MnS@Diatomite and graphene delivered a maximum energy density of 28.9 Wh kg−1 and a maximum power density of 9375 W kg−1 at a potential of 1.5 V. This research lays the groundwork for ideal material preparation as well as a rational design for the electrode material, including property enhancement of diatomite-based material for use in supercapacitors.

Vertically aligned MoS2 thin film catalysts with Fe-Ni sulfide nanoparticles by one-step sulfurization for efficient solar water reduction

• Transferable 2D/3D heterostructure catalysts synthesized via one-step sulfurization. • F1N9S/VMS/ p -Si exhibit excellent photocurrent density and lower onset potential. • No performance degradation during 10 h operation test for the F1N9S/VMS/ p -Si. • Scanning photoelectrochemical microscopy visualize photocurrents on photocathodes. Transferable 2-dimensional (2D) MoS 2 thin films have a versatile potential for constructing highly efficient photoelectrodes when combined with conventional semiconductor light absorbers, taking advantage of its optical transparency and high electrochemical activity. Here, we firstly report fully vertically aligned MoS 2 (VMS)/ p -Si heterostructure photocathode for photoelectrochemical (PEC) water splitting. Furthermore, 3D iron-nickel sulfide nanoparticles of tailored atomic composition are formed simultaneously during the synthesis of VMS via one-step sulfurization to build 3D/2D transition metal sulfide (TMD) heterostructure thin film catalyst. The spectroscopic results reveal that the Fe-doped Ni 3 S 2 nanoparticles on VMS/ p -Si photocathode induce the electrochemically-benign band bending in the overall heterostructure, enabling a significant improvement in PEC performance and long-term stability. Scanning photoelectrochemical microscopy is used to vividly visualize the photocurrent enhancement by the various 3D/2D TMD heterostructures. This work provides promising strategies in developing high performance TMD-based electrocatalysts for practical applications in a wide variety of electrochemical energy conversion processes.

‘Cotton-ball’ shaped porous iron-nickel sulfide: A high-rate cathode for long-life aqueous rechargeable battery

Aqueous rechargeable batteries (ARB) offer reasonably higher energy density and cycle life than their non-aqueous counterparts. Yet, the bottleneck is a limited choice of positive electrodes coupled with low-rate capability and inadequate cycle life. We report here a wet chemical approach to synthesize in-situ three-dimensional (3D) ‘cotton-ball’ shaped porous iron-nickel sulfide (FeNi2S4) (henceforth referred to as PINS) as a diffusion-controlled ARB electrode. It shows a high specific capacity of 177 mA h g−1 at 1 A g−1 vs Pt in the alkaline electrolyte with excellent rate capability (89 mA h g−1 at 40 A g−1) and ultra-long cycle life (10,000 cycles). Furthermore, a pouch-type full-cell ARB (FeNi2S4//AC) delivers an energy density of 56.7 Wh kg−1 at a power density of 871.5 W kg−1 with high cycling stability (10,000 cycles). The present study offers a straightforward and efficient approach for developing nanostructured transition metal sulfide-based cathode materials for practical ARB.

Waste cotton fabric derived porous carbon containing Fe3O4/NiS nanoparticles for electrocatalytic oxygen evolution

Developing low-cost, active and durable electrocatalysts for oxygen evolution reaction (OER) is an urgent task for the applications such as water splitting and rechargeable metal-air battery. Herein, this work reports the fabrication of a metal and hetero atom co-doped fibrous carbon structure derived from cotton textile wastes and its use as an efficient OER catalyst. The free-standing fibrous carbon structure, fabricated with a simple two-step carbonization process, has a high specific surface area of 1796 m2/g and a uniform distribution of Fe3O4/NiS nanoparticles (Fe3O4/NiS@CC). The composite exhibits excellent OER performance with an onset potential of 1.44 V and a low overpotential of 310 mV at the current density of 10 mA/cm2 in a 1.0 M KOH solution, which even surpass commercial RuO2 catalyst. Additionally, this ternary catalyst shows remarkable long-term stability without current density loss after continuous operation for 26 h. It can be believed that the outstanding OER performance is attributed to the synergistic effect between the iron oxides and nickel sulphides, as well as the micro-meso porous carbon structure. This study demonstrates a new strategy to use conventional textile materials to prepare highly efficient electrocatalysts; it also provides a simple approach to turn textile waste into valuable products.

Novel (Ni, Fe)S2/(Ni, Fe)3S4 solid solution hybrid: an efficient electrocatalyst with robust oxygen-evolving performance

Fabrication of high-activity electrocatalysts with operational stability is desperately needed to achieve efficient energy conversion. Herein, for the first time, we highlight a novel electrocatalyst based on binary nickel iron sulfide solid solution hybrids on carbon cloth for oxygen evolution reaction. Benefitting from the synergistic effect of varied phases and the interfacial connection between (Ni, Fe)S2 and (Ni, Fe)3S4 to accelerate the charge transport, the Ni incorporation to optimize the electronic structure of the hybrids and the downshift of the d-band center to facilitate the desorption of oxygen intermediates, the partial charge-transfer between Fe and Ni to boost the generation of catalytically active Ni3+ as well as the unique nanosphere structure to offer enough buffer area for the volume changes during constant redox reactions, the obtained binary nickel iron sulfide hybrids ((Ni, Fe)S2/(Ni, Fe)3S4) display high catalytic reactivity with a low overpotential of 210 mV to reach the current density of 10 mA cm−2, and excellent stability with negligible activity deterioration, making the hybrid a promising candidate for electrocatalytic alkaline water oxidation.

Synthesis of nickel sulfide and nickel–iron sulfide nanoparticles from nickel dithiocarbamate complexes and their photocatalytic activities

Abstract[Ni(dtc)2] (dtc = N‐(pyrrole‐2‐ylmethyl)‐N‐thiophenemethyldithiocarbamate (1), N‐methylferrocenyl‐N‐(2‐phenylethyl)dithiocarbamate (2), N‐furfuryl‐N‐methylferrocenyldithiocarbamate (3), and (N‐[pyrrole‐2‐ylmethyl]‐N‐thiophenemethyldithiocarbamato‐S,S′)(thiocyanato‐N)(triphenylphosphine)nickel(II) (4) complexes were prepared and characterized by elemental analysis, infrared, ultraviolet–visible, and nuclear magnetic resonance (1H and 13C) spectroscopies. The data were consistent with the formation of square planar nickel(II) complexes, which was confirmed by single‐crystal X‐ray diffraction studies on 2 and 4. Fe···Fe interactions exhibited by complex 2 led to supramolecular aggregation. The structure of 4 reveals intermolecular and intramolecular C‐H···Ni anagostic interactions. The anion‐sensing properties of 2 were studied with halide ions by cyclic voltammetry. It was observed that 2 acts as sensor for bromide. Complexes 1, 2, and 3, were utilized to prepare nickel sulfide, nickel–iron sulfide‐1, and nickel–iron sulfide‐2, respectively. The composition, structure, morphology, and optical properties of nickel sulfide and nickel–iron sulfides were examined using powder X‐ray diffraction, transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, ultraviolet–visible, fluorescence, and infrared spectroscopy. Powder X‐ray diffraction patterns of nickel sulfide, nickel–iron sulfide‐1, and nickel–iron sulfide‐2 indicate the formation of orthorhombic Ni9S8, cubic NiFeS2, and cubic Ni2FeS4, respectively. The photocatalytic activities of as‐prepared nickel sulfide and nickel–iron sulfide‐1 nanoparticles were investigated for photodegradation of methylene blue and rhodamine‐B under ultraviolet irradiation. Nickel–iron sulfide‐1 nanoparticles show slightly higher photodegradation efficiency compared with the nickel sulfide nanoparticles.

A multiphase nickel iron sulfide hybrid electrode for highly active oxygen evolution

Development of highly active electrocatalysts for oxygen evolution reaction (OER) is one of the critical issues for water splitting, and most reported catalysts operate at overpotentials above 190 mV. Here we present a multiphase nickel iron sulfide (MPS) hybrid electrode with a hierarchical structure of iron doped NiS and Ni3S2, possessing a benchmark OER activity in alkaline media with a potential as low as 1.33 V ( vs . reversible hydrogen electrode) to drive an OER current density of 10 mA cm−2. The Fe doped NiS, combined with highly conductive disulfide phase on porous Ni foam, is believed to be responsible for the ultrahigh activity. Furthermore, density functional theory simulation reveals that partially oxidized sulfur sites in Fe doped NiS could dramatically lower the energy barrier for the rate-determining elementary reaction, thus contributing to the active oxygen evolution.

Effective removal of chlorinated organic pollutants by bimetallic iron-nickel sulfide activation of peroxydisulfate

Chlorinated organic pollutants (COPs) have caused serious contaminants in soil and groundwater, hence developing methods to remove these pollutants is necessary and urgent. By a simple hydrothermal method, we synthesized the bimetallic iron-nickel sulfide (FeNiS) particles which exhibited excellent catalytic property of COPs removal. FeNiS was chosen as the peroxydisulfate (PDS) activator to removal COPs including 4-chlorophenol (4-CP), 1,4-dichlorophenol (1,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP). The results show that FeNiS can efficiently activate PDS to produce sulfate radical (SO4−) which plays major role in the oxidative dechlorination and degradation due to its strong oxidizing property and the ability of producing hydroxyl radicals (OH) in the alkaline condition. Meanwhile, the Cl− abscised from COPs during the dechlorination can turn into the chlorine radicals and enhance the degradation and cause further mineralization of intermediate products. This bimetallic FeNiS catalyst is a promising PDS activator for removal of chlorinated organics.

Metal distribution in iron-nickel sulfide mineral pentlandite: First-principles study

Pentlandite (Fe,Ni)9S8 has been recently reported in experiments to show a good performance in hydrogen evolution reaction (HER) whose atomic scale mechanism necessarily requires explicit metal distribution. However, the knowledge of its explicit Fe/Ni distribution is lacking, impeding further HER research. In this work, we employed first-principles method to study metal distribution in pentlandite. The results demonstrated that the metal distribution at tetrahedral sites plays a major role in structural stability, where FeNi contact can significantly increase it. Additionally, it is importantly revealed that the metal atoms at octahedral sites can be tailored easily compared with those at tetrahedral sites.