Ni3S2 Nanosheets Research Articles

Vacancy-rich heterogeneous MnCo2O4.5@NiS electrocatalyst for highly efficient overall water splitting

Alkaline water electrolysis is regarded as a promising technology for sustainable energy conversion. Spinel oxides have attracted considerable attention as potential catalysts because of their diverse metal valence states. However, achieving the required current densities at low voltages is a challenge due to its limited active sites and suboptimal electron transport. In this study, we present a novel bifunctional catalyst composed of MnCo2O4.5 nanoneedles grown on NiS nanosheets for water electrolysis. Remarkably, MnCo2O4.5@NiS demonstrates exceptional catalytic activity, requiring 187 and 288 mV to achieve a current density of 100 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. The impressive performance of MnCo2O4.5@NiS is demonstrated by the lower value of voltage 1.44 V needed to deliver the current density of 10 mA cm−2, which outperformed the 1.66 V required for a commercial Pt/C||RuO2 system. Detailed structure analysis and density functional theory (DFT) calculations reveal that the MnCo2O4.5@NiS heterostructure enhances electron transfer at the interface, promotes the formation of oxygen vacancies and tunes the electronic structures of Mn and Co. These findings underscore the potential of MnCo2O4.5@NiS as an efficient and cost-effective electrocatalyst for hydrogen production.

Metallic 1T-MoS2 boosts the kinetics for NiS2-based hybrid supercapacitors with superb rate performance

NiS2 with high theoretical capacitance shows great potential for supercapacitors (SCs). However, the poor cycling stability and sluggish redox kinetics have limited the development of high-rate NiS2-based SCs. Integrating materials with high conductivity potentially reinforces its structure and improves its rate capability. 1T-MoS2 featuring extended interlayer spacing and superior electronic conductivity emerges as an ideal candidate. Therefore, we designed a hybrid material with an alternating interconnected structure of NiS2 and MoS2 with adjustable content of 1T-MoS2. Owing to the improved ion/electron transmittability and the mutual shielding effect, an obvious positive correlation between rate capability and stability with 1T-MoS2 content was established. The optimized 1T-MoS2/NiS2 nanosheets (NMS-2) with 1T phase purity of up to 67.6% in MoS2 demonstrated exceptional specific capacity (579.4 C g−1 at 1 A g−1) and impressive rate capability (345.0 C g−1 at 30 A g−1), which suggests much faster kinetics compared to pure NiS2. Notably, the hybrid supercapacitor (HSC) assembled with NMS-2 as the cathode and activated carbon as the anode (NMS-2//AC HSC) exhibited a maximum specific capacitance of 137.4 F g−1 at 1 A g−1. Furthermore, this HSC can deliver a high energy density of 45.9 Wh kg−1 at 774.9 W kg−1, and could retain 17.7 Wh kg−1 even at a high power density of 7731.7 W kg−1. After 5000 cycles at a high current density of 5 A g−1, the HSC still remained 93.23% of its initial capacitance with an extremely low fading rate of 0.0014% per cycle.

N-doped NiS2 nanosheets array on carbon fiber as an efficient hydrogen evolution reaction electrocatalyst

N-doped NiS2 nanosheets array on carbon fiber as an efficient hydrogen evolution reaction electrocatalyst

Versailles Santa Barbara-5 derived bifunctional one-dimensional electrocatalysts of hierarchical Ni3S2 nanoprism@nanosheets arrays for self-supporting and binder-free efficient supercapacitor and methanol oxidation reaction

We herein present a structure consisting of two-dimensional (2D) single-crystal Ni3S2 nanosheets designed on one-dimensional (1D) Ni3S2 nanoprism arrays (also known as Ni3S2 nanoprism@nanosheets). These arrays are directly synthesized over nickel foam, which is referred to as Ni3S2/NF. These structures can be used as binderless, self-supporting electrodes for bifunctional methanol oxidation reaction (MOR) applications and high energy density hybrid supercapacitors (HSC). Ni3S2/NF is synthesized through the two steps of hydrothermal processes. In step I, 1D hexagonal Versailles Santa Barbara-5 (VSB-5) nanorod arrays have been prepared onto the surface of NF (denoted as VSB-5/NF). The precursor for step II was 1D VSB-5 nanorod arrays, which were transformed into Ni3S2 using Na2S as a sulfur source via the Kirkendall effect. Electrochemical examination results show that as-synthesized Ni3S2/NF electrode exhibited a high specific capacitance (Cs) of 145.0 mA h g−1 at 5 A g−1, low series resistance (0.18 Ω) and charge-transfer resistance (0.05 Ω), small relaxation time constant (τ0 = 8 ms) and high frequency response at 125.8 Hz. Ni3S2/NF has a superior specific capacity of 145.0 mA h g−1 at 5 A g−1 as a SC electrode. The Ni3S2/NF//CNTs/NF HSC can be operated up to 1.6 V in a 3 M KOH electrolyte, delivering an impressive energy density of 256.35 W h kg−1 at a power density of 6400 W kg−1. The as-assembled Ni3S2/NF//CNTs/NF HSC device exhibited an impressive stability of 81 % even after undergoing 10,000 charge-discharge cycles. When compared to previously reported catalysts, Ni3S2/NF was proved to be an excellent electrocatalyst for MOR due to its ability to generate a current density of 215.0 mA cm−2 at 0.5 VSCE, while maintaining a superior and stable current density of 619.2 mA cm−2 at 0.8 VSCE.

Comparison of Modifications for Enhancing the Electrooxidation Performance of Porous Ni Foil Catalytic Electrodes Derived from Paper Templates: Cu-Added Alloying and In Situ Growth of Ni-S Nanosheets

Comparison of Modifications for Enhancing the Electrooxidation Performance of Porous Ni Foil Catalytic Electrodes Derived from Paper Templates: Cu-Added Alloying and In Situ Growth of Ni-S Nanosheets

Hierarchical-hollow architecture NiSe2 nanosheets for overall water splitting

Electrolytic water splitting (EWS), regarded as a sustainable and promising strategy for hydrogen production, has received huge attention in recent years. However, the practical application of EWS is greatly hindered by the sluggish kinetics of the oxygen evolution reaction (OER). Herein, we proposed an efficient strategy for the synthesis of hierarchical hollow nickel selenide with significant HER and OER electrocatalytic activity. The as-synthesized NiSe2 possesses low overpotential of ∼85 mV at the current density of 10 mA/cm2 for the HER in 0.5 M H2SO4 and ∼270 mV for OER in 1 M KOH. Importantly, when employed into full water splitting on membrane electrode assembly, it merely requires an ultralow voltage of 1.73 V to achieve the current density of 1 A/cm2, outperforming most of the reported other Ni/Ni-Se based structures. Density Functional Theory (DFT) simulations confirm that the hierarchical hollow NiSe2 structure facilitates the reduction of the Gibbs free energy change of H- and O-containing intermediates in the HER/OER process, which promotes the formation of intermediates and thus accelerates the catalytic kinetics. This work offers an important structure engineering route to develop high catalytic performance materials and sheds light on the promotion of electrocatalytic activity for clean energy utilization.

Ligand-Induced Electronic Structure Modulation of Self-Evolved Ni3S2 Nanosheets for the Electrocatalytic Oxygen Evolution Reaction.

Modulating the electronic structure of the electrocatalyst plays a vital role in boosting the electrocatalytic performance of the oxygen evolution reaction (OER). In this work, we introduced a one-step solvothermal method to fabricate 1,1-ferrocene dicarboxylic acid (FcDA)-decorated self-evolved nickel sulfide (Ni3S2) nanosheet arrays on a nickel foam (NF) framework (denoted as FcDA-Ni3S2/NF). Benefiting from the interconnected ultrathin nanosheet architecture, ligand dopants induced and facilitated in situ structural reconstruction, and the FcDA-decorated Ni3S2 (FcDA-Ni3S2/NF) outperformed its singly doped and undoped counterparts in terms of OER activity. The optimized FcDA-Ni3S2/NF self-supported electrode presents a remarkably low overpotential of 268 mV to achieve a current density of 10 mA cm-2 for the OER and demonstrates robust electrochemical stability for 48 h in a 1.0 M KOH electrolyte. More importantly, in situ electrochemical Raman spectroscopy reveals the generation of catalytically active oxyhydroxide species (NiOOH) derived from the surface construction during the OER of pristine FcDA-Ni3S2/NF, contributing significantly to its superior electrocatalytic performance. This study concerns the modulation of electronic structure through ligand engineering and may provide profound insight into the design of cost-efficient OER electrocatalysts.

Structural transformations and enhanced electrochemical performance of Co doped NiS2 nanosheets for supercapacitor applications

Doping and morphology tailoring in metal sulfides up to nanoscale plays a vital role for better performance in various applications. Herein hydrothermally synthesized Co-doped nickel sulfide (NiS2) nanostructures have been transformed from nano-rods to nano-sheets up to optimal doping concentration of 3 %. The phase changes, morphological modifications and elemental investigations have been analyzed by SEM, TEM, HRTEM, SAED, EDS, XRD and FTIR. The morphology transitions revealed that NiCo3S exhibited sophisticated morphology of flower like structures formed by nano-sheet patterns. NiCo3S electrode possesses an auspicious capacitance of 1242 Fg_1 at 1 Ag_1 within potential window range of 0.1–0.8 V. In accordance with GCD study, CV and EIS study confirmed that NiCo3S is more electroactive and less resistive showing excellent stability up to 92 % after 5000 cycles. The power law (b = 0.71) showed the capacitive nature of the NiCo3S. The capacitive and diffusive behavior calculated by Dunn’s relationship confirmed the pseudocapacitive charge storage behavior of NiCo3S electrode making this a potential candidate for electrochemical applications.

Synchronously integration of carbon-quantum-dot and Cu, Mo dual-metal doped in Ni3S2@Ni foam toward robust and stable electrocatalytic hydrogen generation

In the pursuit of advancing the production of H2 through hydrogen-evolution reaction (HER), the demand for the elaborate design of cost-effective and robust durability electrocatalysts has gained momentum, especially replacement of noble-metal counterparts like Pt. Herein, we introduce a facile one-pot hydrothermal approach to synthesize nickel foam-supported Ni3S2 nanosheet arrays, which integrate with carbon-quantum-dot (CQDs) and Cu, Mo dual-metal doped. With the introduction of CQDs and Cu, Mo dual-metal doped site, the optimal CQDs-Cu-Mo-Ni3S2@NF exhibits superior HER catalytic activity with a low overpotential of 125 mV at 10 mA·cm−2 and strong durability for 30 h in alkaline medium. The exceptional electrocatalytic performance is ascribed to the synergistic effect of CQDs and Cu, Mo dual-metal site. This synergy encompasses optimization of water molecule adsorption/desorption energetics, elevated electrical conductivity, weakening of the strong S–H bond interaction on the Ni3S2 surface, and providing ample active centers. Furthermore, an in-depth understanding of the electronic structure and adsorption energy during the HER process is probed by density functional theory (DFT) analysis. Our work provides a quintessential paradigm for the rational design of multi-component electrocatalysts for water splitting.

In situ growth of iron incorporated Ni3S2 nanosheet on nickel foam in mediating electron transfer to peroxymonosulfate for pollutant abatement

Catalytic oxidation of organic pollutants is a well-known and effective technique for pollutant abatement. Unfortunately, this method is significantly hindered in practical applications by the low efficiency and difficult recovery of the catalysts in a powdery form. Herein, a three-dimensional (3D) framework of Fe-incorporated Ni3S2 nanosheets in-situ grown on Ni foam (Fe-Ni3S2@NF) was fabricated by a facile two-step hydrothermal process and applied to trigger peroxymonosulfate (PMS) oxidation of organic compounds in water. A homogeneous growth environment enabled the uniform and scalable growth of Fe-Ni3S2 nanosheets on the Ni foam. Fe-Ni3S2@NF possessed outstanding activity and durability in activating PMS, as it effectively facilitated electron transfer from organic pollutants to PMS. Fe-Ni3S2@NF initially supplied electrons to PMS, causing the catalyst to undergo oxidation, and subsequently accepted electrons from organic compounds, returning to its initial state. The introduction of Fe into the Ni3S2 lattice enhanced electrical conductivity, promoting mediated electron transfer between PMS and organic compounds. The 3D conductive Ni foam provided an ideal platform for the nucleation and growth of Fe-Ni3S2, accelerating pollutant abatement due to its porous structure and high conductivity. Furthermore, its monolithic nature simplified the catalyst recycling process. A continuous flow packed-bed reactor by encapsulating Fe-Ni3S2@NF catalyst achieved complete pollutant abatement with continuous operation for 240 h, highlighting its immense potential for practical environmental remediation. This study presents a facile synthesis method for creating a novel type of monolithic catalyst with high activity and durability for decontamination through Fenton-like processes.

Cu, Co co-doped Ni3S2 nanosheets grown on nickel foam as an efficient catalyst for urea oxidation reaction

Doping modification can significantly enhance the catalytic performance of Ni3S2 in urea oxidation reaction (UOR). In this study, we synthesized Cu, Co co-doped Ni3S2 nanosheets on nickel foam (Cu/Co-Ni3S2/NF) through a two-step hydrothermal reaction. Cu, Co dual-doped Ni3S2 nanosheets exhibited a thickness of about 30 nm, composed of nanoparticles. Benefiting from the synergistic regulation of Cu and Co dopants on electronic structure, increased availability of active sites, boosted electron transference rates, and improved electrical conductivity, Cu/Co-Ni3S2/NF exhibited an excellent UOR catalytic performance and enhanced reaction kinetics, offering a low potential of 1.350 V at 100 mA cm-2, along with a low Tafel slope of 15.5 mV dec-1. Moreover, Cu/Co-Ni3S2/NF coupled with Pt/C/NF only necessitated 1.68 V to drive 100 mA cm-2 for overall urea splitting, which is lower than that of traditional water splitting (1.996 V). This indicates that the addition of urea into electrolyte is an energy-conserving strategy for hydrogen production from water electrolysis. This work provides a novel dual-ion doping method to design a highly efficient electrocatalysts for UOR.

Photothermal-regulated selective desorption of enantiomers from Ag/Ni3S2 nanosheet-covered Ni foam

Separation of racemates is critically important in the chemical, agrochemical and pharmaceutical industries, since enantiomers may differ in biological interactions, pharmacology, and toxicity. However, the methods for highly enantioselective separation are still insufficient. In this study, we prepared Ni3S2 nanosheet arrays with excellent photothermal properties using Ni foam as the precursor. The PT enantioselective desorption approach is based on a Ni3S2 NSA decorated with Ag nanoparticles modified with D-penicillamine as the enantioselective substrate. Finite-difference time-domain simulation was used to probe the optimal number, shape, and distribution of Ag NP to optimize the localized surface plasmon resonance and photothermal effect. The enantiomers of 3,4-dihydroxyphenylalanine were used as models to demonstrate enantioselective separation based on the different number of stable hydrogen bonds between the homochiral substrate and each enantiomer. This enantioselective desorption approach has the advantages of efficiency, low cost, and recyclability, and provides a new solution for separating racemic molecules.

The influence of nanostructure and electrolyte concentration on the performance of nickel sulfide (Ni3S2) catalyst for electrochemical overall water splitting

Developing non-precious nanostructured electrocatalysts, exhibiting high catalytic activity in combination with excellent stability, has an enormous potential to replace noble-metal-based catalysts for Hydrogen production through electrochemical water splitting. In this study, a facile method is used for the synthesis of three different hierarchical nanostructures of nickel sulfide (Ni3S2) including nanosheets, nanorods, and multiconnected nanorods that are directly grown on 3D nickel foam (NF). These nanostructured electrocatalysts are evaluated for electrochemical water splitting in alkaline media using four different concentrations to understand the effect of nanostructure and ion concentration on the efficiency. Among different combinations of structure and electrolyte concentration, the Ni3S2 in the form of nanosheets exhibited the best electrocatalytic performance for hydrogen evolution reaction (HER) as well as oxygen evolution reaction (OER) in 3.0 M alkaline solution. The hierarchical Ni3S2 nanosheets exhibited a high electrochemically active surface area, which facilitated the charge transport phenomenon along the electrode–electrolyte interface in a higher electrolyte concentration that improved the reaction kinetics so as overall water splitting. The developed Ni3S2 nanosheets required an overpotential of 110 mV (@10 mA cm−2) and 211 mV (@100 mA cm−2) for HER and OER, respectively in 3.0 M electrolyte concentration. This work provides insight into how the materials’ nanostructures and electrolyte concentration could be utilized to improve the electrocatalytic performance for an overall water-splitting process, and the concept could be applied for material designing and conditions optimization for other catalytic applications.

Construction of NiS/MnCdS S-scheme heterojunction for efficient photocatalytic overall water splitting: Regulation of surface sulfur vacancy and energy band structure

The overall water splitting based on specific photocatalysts is one of the ultimate ways to solve the energy and environmental crisis facing humanity. Sulfide photocatalysts have greater potential in photocatalytic production of solar fuel. However, due to its easy photocorrosion phenomenon, it not effectively driving the water oxidation semi-reaction to produce oxygen, so how to use sulfide photocatalyst to decompose pure water to achieve stoichiometric reaction of H2/O2 production remains a quite challenging task. Herein, sulfur vacancies-rich MnCdS nanoparticles were modified with NiS nanosheets through the hydrothermal derivation method. Different concentration gradients of sulfur-vacancy in MnCdS nanoparticles (MnCdS-Vs-X) with tunable band structures were successful prepared by regulating the concentration of hydrazine hydrate, thus improves the efficiency of light energy utilization and charge separation and the existence of S defects was verified by transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR). The density function theory (DFT) calculation bears out that the draw into of S vacancy adjusted the band structure of MnCdS. Moreover, the successful construction of an S-scheme heterojunction between NiS and MnCdS-Vs-3 has been strongly demonstrated by in-situ XPS and UPS, which promoted interfacial charge separation and further improved the photocatalytic hydrogen evolution efficiency. The as-obtained S-scheme 20 %NiS/MnCdS-Vs-3 heterojunction exhibit excellent visible-light H2 production activity of 4099.55 μmol g−1h−1, 6.75 times higher than pure MnCdS. Most importantly, the excellent and stable photocatalytic overall water splitting activity of H2-509.70 μmol g-1h−1/O2-254.90 μmol g-1h−1 were obtained over 20 % NiS/MnCdS-Vs-3, which further demonstrates the application value of NiS/MnCdS-Vs-3 photocatalysts. This work proposes new ideas for the application of S-vacancies and S-scheme heterojunction in addressing the stability issues associated with sulfide-based photocatalysts in photocatalytic water splitting.

Precisely Control Relationship between Sulfur Vacancy and H Absorption for Boosting Hydrogen Evolution Reaction

HighlightsThe Ar plasma etching strategy was introduced to homogeneously distributed S-vacancies (VS) into the NiS2 nanosheets (NiS2-VS).Build the relationship between sulfur vacancy and H absorption and find that NiS2-VS 5.9% performs outstanding hydrogen evolution reaction performance and remarkable stability.

Innovative solvent-free compound-direct synthesis of defect-rich ultra-thin NiS nanosheets for high-performance supercapacitors.

Defect engineering in NiS nanosheets is an effective method to improve their surface properties and electronic structure for promoting electrochemical properties. However, a tunable, simple, and safe strategy for the introduction of abundant defect sites with a high activity into NiS with a special microstructure is worth developing. Herein, a novel hierarchical micro-flower-like NiS using graphene-like ultra-thin nanosheets with abundant defects as the building blocks was facilely synthesized by an innovative solvent-free compound-direct reaction strategy, which employed cost-efficient NaCl as the friction agent and dispersant to ensure adequate contact between sulfur ions and nickel ions and regulate the growth direction of NiS. Graphene-like ultra-thin NiS nanosheets effectively shorten the transport distance of ions and electrons. Defect engineering in NiS nanosheets provides more adsorption and storage sites for ions and high-activity sites for electrode materials, as well as adjusts the local electronic structure so as to effectively promote ion diffusion and charge transfer. The high performance of the as-obtained N-NiS electrode is illustrated by fabricating an asymmetric supercapacitor, which exhibits a specific capacitance of 351.5 F g-1 and energy density of 71.0 W h kg-1 at a power density of 229.3 W kg-1. The solvent-free compound-direct reaction strategy demonstrated in this study provides a new direction for the synthesis of high-performance nanomaterials for electrochemical energy storage applications.

In situ assembly of Ni3S2 nanosheets encapsulated with NiFe(oxy)hydroxides for efficient water oxidation.

Morphology control plays a pivotal role in achieving an exceptionally efficient electrocatalyst with abundant active sites and outstanding electrical conductivity. In this study, we employed a sophisticated chemical nanoengineering technique to fabricate an exquisitely thin NiFe(OH)x electrocatalyst on Ni3S2 nanosheets. Firstly, the Ni3S2 nanosheets were synthesized through an innovative in situ one-step sulfurization reaction of the Ni(OH)2 nanosheets grown on Ni foam. Subsequently, a remarkable ultrathin layer of NiFe(OH)x was precisely deposited onto the surface of the Ni3S2 to form a captivating core-shell structure using a chemical dipping method. The resulting electrode, denoted as NiFe(OH)x/Ni3S2/NF, exhibited exceptional electrocatalytic activity and durability towards the oxygen evolution reaction (OER), owing to its expansive specific surface area, rapid electron transport, and robust interlayer bonding. Notably, this electrode achieved an impressive current density of 100 mA cm-2 at an astonishingly low overpotential of 218 mV while maintaining a low Tafel slope of 37.9 mV dec-1 and remarkable stability for up to 12 days in 1 M KOH aqueous solution. This work presents an alluring novel approach for constructing highly efficient ultrathin catalysts for water splitting.

Free-standing films of nickel nanowires anchored with Ni3S2 nanosheets for stable Li anodes

A free-standing 3D scaffold of nickel nanowires decorated with lithiophilic Ni3S2 nanosheets was successfully constructed for stable Li anodes.

Mn and Mo co-doped NiS nanosheets induce abundant Ni3+-O bonds for efficient electro-oxidation of biomass.

MnMo-NiS were synthesized for electro-oxidizing ethylene glycol (EG), glycerol (GLY), and 5-hydroxymethylfurfural (HMF), achieving faradaic efficiencies of 97.5%, 98.6%, and 99.2%, and yield rates of 615.7, 475.5, and 333.9 μmol h-1 cm-2. In situ Raman spectroscopy and multi-step chronoamperometry reveal that Ni3+-O is the active site.

Flexible multiscale cavity with omnidirectionality and high stability for in-site SERS detection of nanoplastics on oyster

Nanoplastics are widespread and pose a potential threat to human health. In this work, we designed a flexible multiscale cavity structured (MCS) surface-enhanced Raman scattering (SERS) substrate decorating Ni3S2 nanocavity on a modified polyvinylidene fluoride (PVDF) microcavity. The dense two-dimensional Ni3S2 nanosheets can provide a large surface area for the deposition of plasmonic silver nanoparticles (Ag NPs), increasing the density and strength of the “hotspots”. Additionally, the nanocavity (width ∼500 nm), formed by the nanosheet surroundings, offers not only electromagnetic enhancement of the cavity mode for SERS but also a crucial detection site for nanoplastics attachment. This effectively addresses the challenge of SERS detection due to the scale mismatch between nanoplastics (>50 nm) and conventional “hotspots” (<10 nm). Moreover, the flexible imprinted PVDF microcavity endows the proposed substrate with omnidirectional “hotspots” enhancement, ensuring the signal stability and the feasibility of in-site detection of the actual sample. As a result, we achieved the successful in-site detection of polystyrene (PS) spheres of different sizes on the surface of oysters, with a detection limit of 10-3 mg/mL for 50 nm diameter. The flexible multiscale cavity SERS substrate is expected to show great potential in food safety and environmental monitoring.