Ni3S2 Nanosheets Research Articles

Interfacial electronic modulation of Ni3S2 nanosheet arrays decorated with Au nanoparticles boosts overall water splitting

Rationally design and exploration of bifunctional electrocatalysts with excellent performance towards water splitting is significant for hydrogen energy economy. Herein, a novel Au/Ni3S2 heterostructure catalyst that was composed of self-supported Ni3S2 nanosheets decorated with Au nanoparticles on Ni foam was fabricated. The bifunctional catalyst exhibited excellent catalytic activities towards oxygen evolution reaction (230 mV @ 10 mA cm−2) and hydrogen evolution reaction (97 mV @ 10 mA cm−2) in 1 M KOH. The electrolytic tank using the bifunctional catalyst only required 1.52 V to deliver 10 mA cm−2 and sustained for 60 h, outperforming most of advanced bifunctional catalysts. The X-ray absorption fine structure (XAFS) and density functional theory (DFT) calculations validated that the strong electronic coupling at the interface could modulate the electronic structure of Ni3S2, thereby optimizing the free energies of the adsorbed intermediates. This work provides an atomic-scale insight into the structure-properties relation of a promising heterostructure catalyst for water splitting.

Synthesis of hierarchical Ni3S2@NiMoO4 core-shell nanosheet arrays on Ni foam for high-performance asymmetric supercapacitors

Hierarchical Ni3S2@NiMoO4 core-shell nanosheet arrays were directly fabricated on Ni foam through a simple two-step hydrothermal reaction followed by an annealing treatment. The shell, ultra-thin NiMoO4 nanosheets grew on the surface of the core, interconnected Ni3S2 nanosheet arrays. The growth density of the NiMoO4 nanosheets was adjusted by controlling the hydrothermal reaction time. When the hydrothermal time was 1 h, the as-prepared Ni3S2@NiMoO4 with a core-shell structure could achieve a high specific capacity up to 1121.4 C g−1 at a current density of 5 mA cm−2. In addition, the Ni3S2@NiMoO4 demonstrated 91.6% capacity retention of its initial value for 5000 cycles at a current density of 30 mA cm−2. Additionally, an asymmetric supercapacitor (ASC) device was assembled based on the optimized Ni3S2@NiMoO4 electrode as the positive electrode and activated carbon (AC) as the negative electrode. The ASC exhibited a maximum energy density of 28.4 W h kg−1 at a power density of 90.8 W kg−1, and showed a remarkable cycling performance with 93.1% retention of the initial capacitance after 10,000 cycles at a current density of 30 mA cm−2.

Schottky Heterojunction Nanosheet Array Achieving High‐Current‐Density Oxygen Evolution for Industrial Water Splitting Electrolyzers

AbstractVersatile catalyst systems with large current density under industrial conditions are pivotal to give impetus to hydrogen energy from fundamental to practical applications. Herein, a Schottky heterojunction nanosheet array composed of dispersed NiFe hydroxide nanoparticles and ultrathin NiS nanosheets (NiFe LDH/NiS) is proposed to regulate cooperatively mass transport and electronic structure for triggering oxygen evolution reaction (OER) activity at high current. In catalytic systems, the rich porosity of the NiS nanosheet array contributes abundant catalytic sites and good infiltration of the electrolyte for fast mass transfer. Furthermore, theoretical calculations reveal the coupling of NiFe LDH onto the NiS could tune the d‐band center of Ni(Fe) atoms and the binding strength of oxygen intermediates for favorable OER kinetics. Therefore, the NiFe LDH/NiS Schottky heterojunction exhibits a remarkable OER activity, delivering a current density of 1000 mA cm–2 at the ultralow overpotential of 325 mV. Meanwhile, scaled‐up NiFe LDH/NiS electrodes are implemented in an industrial water splitting electrolyzer and exhibit a stable cell voltage of 2.01 V to deliver a constant catalytic current of 8000 mA over 80 h, saving 0.215 kWh of electricity to generate more hydrogen per cubic meter than commercial Raney Ni electrodes.

NiS nanosheets synthesized by one-step microwave for high-performance supercapacitor

The NiS nanosheets were fabricated using one-step microwave approach with the microwave radiation of 800 W for 1.5 min. Impressively, the NiS nanosheets revealed praiseworthy electrochemical performance, with a capacitance value of 1082.8 F ⋅ g[Formula: see text] at 1 A ⋅ g[Formula: see text] and 77.8% retention over 5000 cycles at 5 A ⋅ g[Formula: see text]. Moreover, an asymmetric supercapacitor was assembled with NiS as the positive electrode and activated carbon (AC) as the negative electrode. It shows 80.42% capacity retention after 8000 cycles and an energy density of 19.45 W ⋅ h ⋅ kg[Formula: see text] at a power density of 801.05 W ⋅ kg[Formula: see text].

Plasma-induced chemical etching generating Ni3S2 for formaldehyde detection

In this paper, Ni3S2 nanosheet (NS) was generated by chemical etching with sodium sulfide directly on the nickel foam (NF), which was induced by dielectric barrier discharge plasma in liquid. Compared with other chemical etching methods of nickel-based nanomaterials, this method was not only rapid (40 min) and mild (at room temperature and atmospheric pressure), but also showed consistent stability and good reproducibility. The Ni3S2 NS/NF electrode showed excellent performance in the electrochemical detection of formaldehyde under alkaline conditions. It had a good linear relationship with the concentration of formaldehyde in the range of 0.002-5.45 mmol/L (R2 = 0.9957) and the limit of detection (LOD) was 1.23 µmol/L (S/N = 3). The sensitivity was 1286.9 µA L mmol‒1 cm‒2, and the response time was about 5 s. The plasma-induced chemical etching strategy provides a simple and stable electrode preparation method, which has great application prospects in nonenzymatic electrochemical sensors.

A Self-Standing 3D Heterostructured N-Doped Co4S3/Ni3S2/NF for High-Performance Overall Water Splitting

Development of efficient electrocatalysts with earth-abundant materials for water splitting is of paramount significance for energy harvesting and storage. Here, novel nickel foam-supported nitrogen-doped Co4S3/Ni3S2 heterostructured nanosheets (denoted as N-Co4S3/Ni3S2/NF) were synthesized for water splitting. The self-standing 3D electrocatalysts consisting of Co4S3 nanocrystals and Ni3S2 nanosheets show an abundant interface of Co4S3/Ni3S2 and a high density of defects of nitrogen doping as catalytic active sites to improve electronic band structure and efficient charge transfer ability. The as-prepared N-Co4S3/Ni3S2/NF exhibits superior OER performance (overpotential of 331 mV at 100 mA cm−2) and enhanced HER performance (overpotential of 150 mV at 10 mA cm−2). Eventually, a high-performance electrolyzer (N-Co4S3/Ni3S2/NF//N-Co4S3/Ni3S2/NF) was assembled for overall water splitting with a low cell voltage of 1.647 V at 10 mA cm−2. The rational structural design and nitrogen doping present a wide range of possibilities for the further development of highly efficient electrocatalysts based on earth abundant elements.

Reduced graphene oxide decorated amorphous NiS2 nanosheets as high-performance anode materials for enhanced sodium-ion hybrid capacitors

Reduced graphene oxide decorated amorphous NiS2 nanosheets as high-performance anode materials for enhanced sodium-ion hybrid capacitors

Accessible active sites activated by cobalt-doping into MoS2/NiS2 nanosheet array electrocatalyst for enhanced hydrogen evolution reaction

It is of great importance to develop highly efficient electrocatalysts with low-cost, superior activity and good stability toward hydrogen production. The conductivity property and catalytic activity of transition metal electrocatalyst can be desirable optimized by metal doping for hydrogen evolution reaction (HER). Herein, a Co-doped MoS2/NiS2 nanosheet array was in-situ covered on the carbon cloth substrate (Co-MoS2/NiS2/CC) via facile successive three-step hydrothermal processes, in which Co-MoS2 nanosheets were hierarchically integrated with NiS2 nanosheets. Benefitting from the introduction of Co atom and numerous heterostructures, the as-obtained Co-MoS2/NiS2/CC allows high conductivity and plenty of accessible active sites, showing favorable synergistic effect for electrocatalytic HER properties. Specifically, the optimal Co-MoS2/NiS2/CC electrocatalyst requires low overpotentials of 92 and 122 mV to deliver current densities of 10 and 50 mA cm−2 in 0.5 M H2SO4. It presents excellent electrocatalytic activity in 0.1 M KOH simultaneously. Moreover, such a Co-MoS2/NiS2/CC electrocatalyst shows a small Tafel slope of 47 mV dec−1 and remarkable long-term stability. This work provides a novel strategy to synthesize transition metal-doped heterogeneous electrocatalysts for efficient hydrogen evolution reaction.

3D-Stretched Film Ni3 S2 Nanosheet/Macromolecule Anthraquinone Derivative Polymers for Electrocatalytic Overall Water Splitting.

For the first time, anew polymer electrode AQS/S is prepared by compositing Ni3 S2 nanosheets and macromolecular anthraquinone derivative (AQD) supported on nickel foam with flying colors. The AQS/S exhibits high crystalline structure and abundant S defects. Density of state calculation shows that AQD has stable internal bonding and easy external bonding with metals, conducive to the dispersion of metal reaction sites, ensuring excellent activity and high stability.Under 1.0 m KOH solution, ultralow overpotentials of 62 and 133 mV at 10 mA cm-2 on AQS/S for hydrogen evolution reaction and on activated AQS/S (A-AQS/S) for oxygen evolution reaction, respectively, are achieved. 100 h chronopotentiometry and the cyclic voltammetry tests show that catalysts have high durability. The AQS/S‖A-AQS/S two-electrode system is also found to have good electrocatalytic activity for 1.43V to get 10mA cm-2 in overall water splitting, better than the state-of-the-art 20% Pt/C‖RuO2 combination.

Rational design of nanorod-supported Ni3S2 nanosheet array for advanced asymmetric pseudocapacitor with a great energy density

Rational design of nanorod-supported Ni3S2 nanosheet array for advanced asymmetric pseudocapacitor with a great energy density

Co-doped Ni3S2 ultrathin nanosheets for efficient oxygen evolution catalysis

Oxygen evolution reaction (OER) sets the huge obstacle for water electrolysis application, and the low-cost catalysts with small overpotential and fast kinetics are highly needed. Herein, cobalt-doped Ni3S2 nanosheets constructed flower-like architecture is grown on nickel foam (Co-Ni3S2/NF) toward OER application. It is found that, heteroatom doping induces positive effects for OER, including the modulated electronic structure, more active sites, and accelerated charge transfer. Nanosheets structure assures exposed active sites and shortened charge transfer path. Benefited from the aforementioned advantages, the as-prepared sample exhibits impressive catalysis performances, such as ultralow overpotential of 160 mV at current density of 10 mA cm−2, small Tafel slope of 49 mV dec−1, and high stability, which behaves as the promising catalyst for OER.

Construction of NiSe2/BiVO4 Schottky junction derived from work function discrepancy for boosting photocatalytic activity

The rapid recombination of photogenerated carriers limits the photocatalytic activity of BiVO4. Here, we grew NiSe2 nanosheets on the surface of BiVO4 through a facile solvothermal method to construct a Schottky junction. Due to the discrepancy of work function, electrons at the interface are transferred from BiVO4 to NiSe2, thereby forming a built-in electric field. In virtue of the built-in electric field and the good conductivity of NiSe2, the photo-generated carriers can be quickly separated and transferred. In addition, the interaction at the interface reduces the band gap of BiVO4, which increases the absorption of visible light. These above benefits improve the photocatalytic performance. The photocatalytic reaction under visible light shows that the degradation rate of RhB for 9 mol% NiSe2 composited BiVO4 increases by 11 times compared with pure BiVO4. The simplicity of the preparation method and the significantly improved performance show the enormous potential of NiSe2 to be coupled with other semiconductor photocatalysts to improve their catalytic activity.

Synthesis of core-shell structured Ni3S2@MnMoO4 nanosheet arrays on Ni foam for asymmetric supercapacitors with superior performance

The present study successfully synthesized core-shell structured Ni3S2@MnMoO4 nanosheet arrays on Ni foam via a simple two-step hydrothermal method followed by the annealing process. MnMoO4 nanosheets as the shell were grown on the surface of the Ni3S2 nanosheet as the core, and the growth density of the MnMoO4 nanosheets was controlled by changing the hydrothermal time. The optimized Ni3S2@MnMoO4 electrode was able to deliver a specific capacity of 979.3 C g−1 at a current density of 2 mA cm−2 in a 2 M KOH solution and also exhibited an ultrahigh cycling stability of 88.3% capacity retention after 7000 charge-discharge cycles under a current density of 10 mA cm−2. In addition, an asymmetric supercapacitor (ASC) device was fabricated using the optimized electrode as the positive electrode and activated carbon (AC) as the negative electrode, and its electrochemical performance was determined. The device achieved a maximal energy density of 31.4 W h kg−1 at a power density of 399.9 W kg−1 as well as an excellent cycling stability with 91.3% retention of its initial value at a high current density of 20 mA cm−2.

Construction of layered C@MnNiCo–OH/Ni3S2 core–shell heterostructure with enhanced electrochemical performance for asymmetric supercapacitor

Transition metal hydroxides with three-dimensional heterostructure have been proved to be promising candidates as the electrode materials for energy storage. Herein, a layered C@MnNiCo–OH/Ni3S2 core-shell heterostructure, composed of grass-like Ni3S2 nanosheets, interlaced ultrathin MnNiCo–OH nanosheets and the coated amorphous carbon, has been successfully designed and synthesized by the facile hydrothermal and electrodeposition processes, which exhibits superior electrochemical performance. The unique core-shell structure is conductive to enlarge the active sites and provide charge transfer rate and redox reactions. The specific capacitance of the C@MnNiCo–OH/Ni3S2/NF electrode could reach 2332 mF cm−2 at 1 mA cm−2 and reserves 89.45 % capacitance after 5000 continuous cycles. Besides, the two-electrode device assembled by C@MnNiCo–OH/Ni3S2/NF and activated carbon (C@MnNiCo–OH/Ni3S2/NF//AC) shows an excellent density of 73.84 Wh kg−1 at 800 W kg−1. The remarkable performances make it possible for the C@MnNiCo–OH/Ni3S2/NF nanocomposite to apply in the area of conversion and energy storage.

Fe-cation Doping in NiSe2 as an Effective Method of Electronic Structure Modulation towards High-Performance Lithium-Sulfur Batteries.

The commercialization of Li-S batteries is hindered by the shuttling of lithium polysulfides (LiPSs), the sluggish sulfur redox kinetics as well as the low sulfur utilization during charge/discharge processes. Herein, a free-standing cathode material was developed, based on Fe-doped NiSe2 nanosheets grown on activated carbon cloth substrates (Fe-NiSe2 /ACC) for high-performance Li-S batteries. Fe-doping in NiSe2 plays a key role in the electronic structure modulation of NiSe2 , enabling improved charge transfer with the adsorbed LiPSs molecules, stronger interactions with the active sulfur species and higher electrical conductivity. Effective promotion of the sulfur redox kinetics and enhanced sulfur utilization were achieved under high areal sulfur loadings. The stronger interactions with LiPSs together with the unique 3D structure of Fe-NiSe2 /ACC also induced the transformation of Li2 S2 /Li2 S growth from conventional 2D films to 3D particles, significantly eliminating the barriers of solid nucleation and growth during the phase transition of liquid LiPSs to solid Li2 S2 /Li2 S. With a high sulfur loading of 9.9 mg cm-2 , the Fe-NiSe2 /ACC cathode enabled a high area capacity of 9.14 mAh cm-2 with a low average decay of 0.11 % per cycle over 200 cycles at 0.1 C.

NiFe2O4–Ni3S2 nanorod array/Ni foam composite catalyst indirectly controlled by Fe3+ immersion for an efficient oxygen evolution reaction

A NiFe alloy was designed on nickel foam (NF) as a precursor using cathodic electrodeposition. NiFe2O4–Ni3S2 nanorods (NRs) composite catalysts were prepared by Fe3+ impregnation and further hydrothermal sulfuration methods. NiFe2O4–Ni3S2 nanosheets (NSs) were also prepared by direct hydrothermal sulfuration of the NiFe alloy for comparison. Compared to the dense NS structure of the NiFe2O4–Ni3S2 NSs/NF, the NiFe2O4–Ni3S2 NRs/NF showed better oxygen evolution performance due to its unique weed-like NR array structure composed of additional oxygen evolution reaction (OER) active sites, with a strong electron interaction for Ni and Fe and the active sulfide synergistic effect with oxides. Therefore, Driving a current density of 10 mA cm−2 only requires an overpotential of 189 mV and the catalyst could provide 100 mA cm−2 continuously and be constant for more than 80 h in 1.0 M KOH. This experiment indicated that Fe3+ immersion had an indirect regulating effect on the morphological growth of the catalyst, which provided a novel concept for designing better OER catalysts.

Efficient MOF- derived V–Ni3S2 nanosheet arrays for electrocatalytic overall water splitting in alkali

The synergistic achievement of low-cost earth-abundant electrocatalysts and high efficiency to meet renewable energy need is highly desirable yet challenging. Here, we developed a simple Ni foam self -templating route for V-doped Ni3S2 nanosheet arrays through in situ formation of metal-organic frameworks (MOFs) combined with subsequent conversion. The as-prepared MOF-V-Ni3S2/NF catalyst delivers outstanding electrocatalytic performance in the alkaline solution, which requires low overpotentials of 118.1 mV @10 mA cm−2 and 268 mV @10 mA cm−2 for hydrogen evolution reaction and oxygen evolution reaction, respectively. The V-doping and MOF-derived 3D hieratical nanostructure play a vital role in the catalytic process, which provides efficient active sites and large surface areas. Furthermore, an alkaline electrolyzer was assembled with two pieces of MOF-V-Ni3S2/NF, which achieves efficient water splitting at 1.58 V @10 mA cm−2. This strategy opens up new channels to synthesize MOF-based bifunctional electrocatalysts toward overall water spitting.

Construction of NiS Nanosheets Anchored on the Inner Surface of Nitrogen-Doped Hollow Carbon Matrixes with Enhanced Sodium and Potassium Storage Performances

Although nickel sulfides with high theoretical capacities have been demonstrated as promising anodes for sodium/potassium ion batteries (SIBs/KIBs), they always suffer from large volume expansion and inferior electronic conductivity, resulting in irreversible capacity loss. In this work, we design and prepare NiS nanosheets attached to the inner surface of the hole in nitrogen-doped carbon matrixes (h-NiS@N-C), which could provide much more exposed active sites for electrochemical reactions for SIBs and KIBs. The void space in nitrogen-doped carbon matrixes not only could largely buffer volume expansion of NiS nanosheets but also could store the electrolyte and shorten the diffusion distance for ions during the discharge/charge process. The h-NiS@N-C exhibits a reversible capacity of 510 and 500 mA h g–1 after 200 cycles at 100 mA g–1 for SIBs and KIBs, respectively. When tested at a high current density of 1 A g–1, it displays a long-term cycling stability over 1000 cycles with a capacity of 290 and 260 mA h g–1 for SIBs and KIBs, respectively. Furthermore, the sodium full battery performance suggests that the h-NiS@N-C has application potential for energy-storage devices.

The rational design of Ni3S2 nanosheets–Ag nanorods on Ni foam with improved hydrogen adsorption sites for the hydrogen evolution reaction

Heterostructures made of Ni3S2 nanosheets–Ag nanorods on Ni foam are rationally designed as efficient electrocatalysts for the HER under alkaline conditions.

Construction of self-supporting, hierarchically structured caterpillar-like NiCo2S4 arrays as an efficient trifunctional electrocatalyst for water and urea electrolysis.

In this study, we have developed intriguing self-supporting caterpillar-like spinel NiCo2S4 arrays with a hierarchical structure of nanowires on a nanosheet skeleton, which can be used as a self-supporting trifunctional electrocatalyst for the oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). The caterpillar-like NiCo precursor arrays are first in situ grown on carbon cloth (NiCo2O4/CC) by a facile hydrothermal reaction, which is followed by an anion exchange process (or sulfuration treatment) with Na2S to form self-supporting spinel NiCo2S4 arrays (NiCo2S4/CC) with a roughened nanostructure. Taking advantage of the bimetallic synergistic effect, the unique hierarchical nanostructure, and the self-supporting nature, the resultant NiCo2S4/CC electrode exhibits high activities toward the OER, HER and UOR, which are highly superior to the monometallic counterparts of NiS nanosheets and Co9S8 nanowires on a carbon cloth substrate. The comparison of the three electrodes also indicates that the hierarchically structured bimetallic electrode combines the morphological and structural characteristics of monometallic Ni-based nanosheets and Co-based nanowires. When assembling a two-electrode electrolytic cell with NiCo2S4/CC as both the anode and cathode, an applied cell voltage of only 1.66 V is required to deliver a current density of 10 mA cm-2 in water electrolysis. By using the same two-electrode setup, the applied voltage for urea electrolysis is further reduced to 1.45 V that produces hydrogen at the cathode with the same current density. This study paves the way for exploring the feasibility of future less energy-intensive and large-scale hydrogen production.