NiS Nanoparticles Research Articles

Porous carbon nanorods decorated with graphitic carbon bubbles encapsulated NiSe nanoparticles as an efficient microwave absorber

Microwave absorbers have been applied extensively to attenuate harmful electromagnetic radiation. In this study, efficient microwave absorbers are successfully prepared using metal-organic frameworks as precursors through a convenient in-situ growth and selenization approach in which NiSe nanoparticles are embedded in rod-like carbon networks decorated with graphitic carbon bubbles. The chemical composition, microstructure, graphitization degree, and corresponding microwave absorption performance are well controlled by changing the selenization condition. Remarkably, the reflection loss of the NiSe/C composite obtained at 700 °C reached −59.70 dB at 7.89 GHz and the effective absorption bandwidth was 4.67 GHz. In the as-prepared composite, pervasive carbon networks help improve conductive loss. The homogeneous interfaces between metal selenides and carbon, as well as the abundant defects and interfaces in the graphitic carbon bubbles, boost interfacial polarization and accelerate electron transfer, contributing to the high-performance absorption.

A dual-template imprinted polymer electrochemical sensor based on AuNPs and nitrogen-doped graphene oxide quantum dots coated on NiS2/biomass carbon for simultaneous determination of dopamine and chlorpromazine

In this study, a dual template molecularly imprinted electrochemical sensor was fabricated for the simultaneous determination of dopamine (DA) and chlorpromazine (CPZ). Nitrogen-doped graphene oxide quantum dots (N-GOQDs) and gold nanoparticles (AuNPs) were deposited on a combination of biomass carbon and biomass-derived asymmetric carbon-based nanospheres decorated with NiS2 nanoparticles (NiS2/BC), and the obtained material was used to modify glass carbon electrode (GCE). The electropolymerization of nicotinamide (NA) on Au/N-GOQDs/NiS2/BC/GCE via cyclic voltammetry (CV) using NA as functional monomer and DA and CPZ as template was used to produce molecularly imprinted polymer (MIP) film. Various experimental parameters, including electropolymerization cycles, template-to-functional monomer ratio, pH value, elution time, and incubation time, were optimized. Differential pulse voltammetry (DPV) response under optimized parameters show two linear ranges for DA (0.05–8 µM and 8–40 µM), and the limit of detection (LOD) is as low as 2.8 nM (S/N = 3). CPZ had a linearity range of 0.005–2 µM with very low LOD value of 0.25 nM (S/N = 3). The prepared MIP electrochemical sensor had good reproducibility and repeatability, acceptable stability, and high selectivity for DA and CPZ. Furthermore, the sensor was used in real sample analysis of human serum, urine and pharmaceutical samples, and the result of recovery (93.9%–106.15%) and relative standard deviation (RSD) (1.5%–6.6%) indicated good practicality.

Cellulose as Sacrificial Biomass for Photocatalytic Hydrogen Evolution over One‐dimensional CdS Loaded with NiS2 as a Cocatalyst

AbstractNiS2 nanoparticles (NPs)‐modified CdS nanowires (NWs) (NiS2/CdS) with varying amount of NiS2 were synthesized via a two‐step approach and characterized for sustainable hydrogen evolution. They showed much higher activity than pristine CdS NWs or NiS2 NPs, with the optimal hydrogen production rate reaching 14.49 mmol⋅h−1⋅g−1 for 40%‐NiS2/CdS with lactic acid as sacrificial agent. Under optimal conditions, hydrogen generation rate of 52.88 μmol⋅h−1⋅g−1 was achieved using single cellulose as sacrificial agent. Photoelectrochemical (PEC) properties of the NiS2/CdS nanocomposites were investigated to gain a better understanding of the mechanism behind the enhanced photocatalytic hydrogen evolution reaction (HER) activity. Furthermore, ultrafast transient absorption (TA) spectroscopy was also employed to investigate the charge carrier dynamics, revealing an exciton lifetime approximately four times shorter in 40%‐NiS2/CdS nanocomposite compared to pristine CdS NWs. These results suggest efficient charge transfer from CdS to NiS2. A possible mechanism for enhanced hydrogen production over NiS2/CdS nanocomposite is proposed.

Efficient and Stable Photocatalytic Hydrogen Evolution Activity of Multi-Heterojunction Composite Photocatalysts: CdS and NiS2 Co-modified NaNbO3 Nanocubes.

In this study, a NaNbO3/CdS/NiS2 ternary composite photocatalyst containing no precious metals was successfully prepared by a simple hydrothermal method. The prepared ternary photocatalyst has a significant improvement in photocatalytic performance of hydrogen production from water splitting under visible light irradiation. The best sample NCN40% hydrogen production rate is 4.698 mmol g−1 h−1, which is about 24.7 times that of pure CdS sample. In addition, the stability of the composite catalyst in the long-term photocatalytic hydrogen production cycle is also improved. The reason for the enhanced hydrogen production performance may be the optimization of the microstructure of the catalyst and the reduction of photogenerated electron-hole recombination. The construction of multi-heterojunctions (NaNbO3-CdS, CdS–NiS2, and NaNbO3-NiS2) helps to reduce the recombination of carriers. Furthermore, the in-situ-formed NiS2 nanoparticles can serve as active sites for hydrogen evolution. All of these factors induced the improved photocatalytic activity of the as-prepared ternary photocatalyst.

Hydrogen Evolution and Wastewater Treatment of Hydrangeal‐like Catalyst Decroatedby the NiS Nanosheet and PdNanoparticle

AbstractMultifunctional catalysts with photodegradation of organic contaminants and electrocatalytic hydrogen evolution are extremely urgent. In this work, a unique MoS2 hollow microsphere with a diameter of 1.5 μm was fabricated without adding any spherical template by an improved hydrothermal process. Interestingly, the MoS2 hollow microspheres with introduction of the NiS and Pd nanoparticles greatly restrain recombination rates of electron‐hole pairs, resulting in the outstanding photocatalytic activity. The RhB removal rates of the MoS2 hollow microsphere and the NPMS composites were 7 and 10 times higher than that of pure MoS2, respectively, for the high concentration of macrocyclic contaminants under visible‐light illumination. Furthermore, the optimal robust NPMS hybrids exhibite a lower overpotential of 100 mV (at 10 mV cm−2) and a smaller Tafel slope of 50 mV dec−1. The unique structure composite catalysts possess more exposed active sites and defects to enhance the catalytic activity for HER and removal of organic pollution.

Metallic sulfide nanoparticles anchored graphene oxide: Synthesis, characterization and reduction of methylene blue to leuco methylene blue in aqueous mixtures

Oxidizing graphite (Gt) to graphene oxide (GO) through non-explosive oxidizing mixture at 55 °C is reported with high yield. GO was anchored with NiS, ZnS, and CdS metallic sulfide nanoparticles (MSNPs) in 1:1 ratio at 85 °C. MSNPs were obtained by using chloride salts of Ni, Zn, and Cd metals with thiourea in 1:3 ratio in aqueous GO for in situ doping. The GO and MSNPs doped GO (MSNP-GO) were characterized with X-ray diffraction (XRD), FTIR, UV–Vis spectrophotometry, Raman spectroscopy and thermogravimetric analysis (TGA). The GO, CdS-GO, NiS-GO, ZnS-GO had photocatalyzed methylene blue (MB) reduction by 88, 97.22, 79.68, and 89.87% to leuco MB (LMB) colorless, in aqueous medium respectively. Contrary to NiS-GO, the CdS and ZnS increased MB reduction by 9 and 1.87% respectively by weakening intersheet Vander Waals forces of GO for availing surface area. Ni2+ with 3d8 catalyzed 8.32% less MB to LMB than Zn2+ with 3d10 and Cd2+ with 4d10. MSNPs were uniformly anchored within the 2D GO sheets through sulfide anions (S2−) releasing activity for a higher reduction from water and electronically active solvents. MSNP-GO-MB-LMB ventures a novel host-guest chemistry as the MB with sp2 along with sp2-sp3 hybridizations of GO are photocatalyzed to LMB. MSNP-GO-MB-LMB formulates a multifunctional nanocluster to absorb solar radiation energy and heat contents due to MSNPs-GO interfaces. Likewise ethylene (EB) and propylene blue (PB) could be separated through selective reductions as per their hydrophobicity.

Understanding the growth of NiSe nanoparticles on reduced graphene oxide as efficient electrocatalysts for methanol oxidation reaction

With the development of direct methanol fuel cell (DMFC), methanol oxidation reaction (MOR) becomes the crux of the application of DMFC, and the preparation of cheap, efficient MOR electrocatalyst is still the focus of researchers. Hence, we have prepared NiSe/RGO nanoparticles by a simple and universal way using pyrolyzation and selenylation. The MOR of NiSe/RGO is tested in 0.5 M MeOH/1 M KOH solution. Compared with the precursor Ni, NiSe/RGO-550 has outstanding performance for MOR with onset potential is 1.35 V vs. RHE, and 59.84 mA cm−2 for peak current density, and it can stable catalytic oxidation of methanol more than 4000 s. Because of the augment of active sites after selenization and the load of RGO enhanced electroconductibility, NiSe/RGO-550 has remarkable performance for MOR. This work provides the possibility of high performance, low cost catalysts for energy storage, conversion and practical applications.

Fe, Al-co-doped NiSe2 nanoparticles on reduced graphene oxide as an efficient bifunctional electrocatalyst for overall water splitting.

Developing low-cost and highly efficient electrocatalysts for overall water splitting is of far-reaching significance for new energy conversion. Herein, dual-cation Fe, Al-co-doped NiSe2 nanoparticles on reduced graphene oxide (Fe, Al-NiSe2/rGO) were prepared as a bifunctional electrocatalyst for overall water splitting. The dual-cation doping can induce a stronger electronic interaction between the foreign atoms and host catalyst, for optimizing the adsorption energy of reaction intermediates. Meanwhile, the leaching out of Al from the crystal structure of the target product during the alkaline wash creates more defects and increases the active site exposure. As a result, the Fe, Al-NiSe2/rGO catalyst exhibits excellent catalytic activities for both the OER and HER with an overpotential of 272 mV @η10 for the OER in 1.0 M KOH and 197 mV @η10 for the HER in 0.5 M H2SO4, respectively. A two-electrode electrolyzer using Fe, Al-NiSe2/rGO as the anode and cathode shows a low voltage of 1.70 V at the current density of 10 mA cm-2. This study emphasizes the synergistic contribution of the dual-cation co-doping effect and more defects created by Al leaching to boost the performance of water splitting.

NiS2 nanoparticles anchored on open carbon nanohelmets as an advanced anode for lithium-ion batteries.

Low intrinsic conductivity and large volume expansion seriously restrict the efficient lithium storage performance of metal sulfides. Here, we fabricate a hybrid material of NiS2 nanoparticles/carbon nanohelmets (NiS2/CNHs) to address the above issues. As an anode material in lithium-ion batteries, NiS2/CNHs exhibit excellent cycling stability (490 mA h g−1 after 3000 cycles at 5 A g−1) and rate properties (412 mA h g−1 at 10 A g−1), outperforming other NiSx-based anode materials. These remarkable performances originate from the three-dimensional helmet-like integrated architecture of NiS2/CNHs, which reduces the electrode resistance due to the tight combination between NiS2 and CNHs, provides efficient diffusion paths for the electrolyte and Li+ owing to the amorphous nanoporous carbon structure, and significantly mitigates the aggregation and buffers the large volumetric expansion of NiS2 nanoparticles upon long-term cycling thanks to the open three-dimensional architecture and well-dispersed NiS2 nanoparticles on it.

Nickel sulfide-incorporated sulfur-doped graphitic carbon nitride nanohybrid interface for non-enzymatic electrochemical sensing of glucose.

A nickel sulfide-incorporated sulfur-doped graphitic carbon nitride (NiS/S-g-C3N4) nanohybrid was utilized as an interface material for the non-enzymatic sensing of glucose in an alkaline medium (0.1 M NaOH). The precursors used in the preparation of NiS/S-g-C3N4 hybrid were thiourea and nickel nitrate hexahydrate as the sulfur and nickel sources, respectively. The HRTEM results reveal that NiS nanoparticles incorporated on the S-g-C3N4 nanosheet surface could enhance the electrocatalytic activity and electrical conductivity. The prepared NiS/S-g-C3N4 crystalline nature, surface functionalities, graphitic nature, thermal stability and surface composition were investigated using XRD, FT-IR, Raman spectroscopy, TGA and XPS analyses. The NiS/S-g-C3N4 modified electrode was used for the non-enzymatic sensing of glucose at an applied potential of 0.55 V vs. Ag/AgCl with a detection limit of 1.5 μM (S/N = 3), sensitivity of 80 μA mM−1 cm−2 and the response time of the fabricated sensor was close to 5 s. Different inorganic ions and organic substances did not interfere during glucose sensing. The NiS/S-g-C3N4 nanohybrid material could be extended for a real sample analysis and open the way for diverse opportunities in the electrochemical sensing of glucose.

Electrodeposition of NiS/Ni2P nanoparticles embedded in amorphous Ni(OH)2 nanosheets as an efficient and durable dual-functional electrocatalyst for overall water splitting

To develop earth-abundant and cost-effective catalysts for overall water splitting is still a major challenge. Herein, a unique “raisins-on-bread” Ni–S–P electrocatalyst with NiS and Ni2P nanoparticles embedded in amorphous Ni(OH)2 nanosheets is fabricated on Ni foam by a facile and controllable electrodeposition approach. It only requires an overpotential of 120 mV for HER and 219 mV for OER to reach the current density of 10 mA cm−2 in 1 M KOH solution. Employed as the anode and cathode, it demonstrates extraordinary electrocatalytic overall water splitting activity (cell voltage of only 1.58 V @ 10 mA cm−2) and ultra-stability (160 h @ 10 mA cm−2 or 120 h @50 mA cm−2) in alkaline media. The synergetic electronic interactions, enhanced mass and charge transfers at the heterointerfaces facilitate HER and OER processes. Combined with a silicon PV cell, this Ni–S–P bifunctional catalyst also exhibits highly efficient solar-driven water splitting with a solar-to-hydrogen conversion efficiency of 12.5%.

Synthesis of NiS–MoO3 nanocomposites and decorated on graphene oxides for heterogeneous photocatalysis, antibacterial and antioxidant activities

Preparation of metal sulfide/oxide nanoparticles and decoration on graphene oxide is the aim of significant research for extending great stable catalysts in wide-area light. Here, we indicated synthesis of hybrid metal sulfide/oxide nanocomposites, NiS–MoO3 and decorated on graphene oxide using hydrothermal method. The NiS–MoO3/graphene oxide nanocomposites were characterized by X-ray diffraction/photo-electron, electron microscopy, UV–vis spectroscopy. The outcomes have demonstrated that NiS nanoparticles were completely distributed on the MoO3 nanoparticles surface. The photo-degradation of methyl orange under visible, and ultraviolet irradiation was applied to investigate the photocatalytic performance of NiS–MoO3/graphene oxide nanocomposites prepared. It is obtained that the photocatalysis process under UV light is much faster than the visible light. The stability of NiS–MoO3/graphene oxide nanocomposites was evaluated through cyclic photo-degradation test. Next, the bactericidal experiment was carried out against E. coli and S. pyogenes using NiS–MoO3/graphene oxide nanocomposites as the antibacterial agents. The antioxidant data represented the excellent properties of NiS–MoO3/graphene oxide nanocomposites for this study.

Engineering ultrafine NiS cocatalysts as active sites to boost photocatalytic hydrogen production of MgAl layered double hydroxide

Nonprecious cocatalyst decoration is of great importance to create more active sites on the photocatalyst surface and provides insights into the photocatalytic activity enhancement. Herein, through facile hydrothermal and precipitation routes, the surface of MgAl layered double hydroxide (LDH) was modified by ultrafine NiS nanoparticles as a cocatalyst to design MgAl-LDH/NiS hybrid photocatalysts for highly-efficient photocatalytic hydrogen generation. The presence of NiS not only enhances the visible-light absorption but also promotes the separation and transfer of photogenerated charges, thereby boosting the photocatalytic activity of MgAl-LDH/NiS (35.8 μmol h−1) compared with bare MgAl-LDH (2.7 μmol h−1). The MgAl-LDH/NiS hybrid, moreover, displays a superior stability towards photocatalytic hydrogen evolution. This research offers a facile route to develop a high-performance photocatalyst using low-cost metal sulfide as cocatalyst for visible light photocatalytic hydrogen production.

Reduced Graphene Oxides Decorated NiSe Nanoparticles as High Performance Electrodes for Na/Li Storage.

A facile, one-pot hydrothermal method was used to synthesize Nickel selenide (NiSe) nanoparticles decorated with reduced graphene oxide nanosheets (rGO), denoted as NiSe/rGO. The NiSe/rGO exhibits good electrochemical performance when tested as anodes for Na-ion batteries (SIBs) and Li-ion batteries (LIBs). An initial reversible capacity of 423 mA h g−1 is achieved for SIBs with excellent cyclability (378 mA h g−1 for 50th cycle at 0.05 A g−1). As anode for LIBs, it delivers a remarkable reversible specific capacity of 1125 mA h g−1 at 0.05 A g−1. The enhanced electrochemical performance of NiSe/rGO nanocomposites can be ascribed to the synergic effects between NiSe nanoparticles and rGO, which provide high conductivity and large specific surface area, indicating NiSe/rGO as very promising Na/Li storage materials.

Hierarchical Nanostructured NiS/MoS2/C Composite Hollow Spheres for High Performance Sodium-Ion Storage Performance.

Development of high performance electrode materials for sodium-ion batteries has been given a lot of attention in recent years but challenges remain. Herein, we have successfully synthesized the first NiS/MoS2/C composite hollow spheres (NMSCHSs) via a facile hard template method combined with calcined sulfidation process. Owing to its unique hierarchical nanostructure with NiS nanoparticles embedded in shell wrapped with MoS2 nanosheets, the NMSCHS-based anode electrodes exhibit superior rate capability and cycling stability, with a specific discharge capacity of 516 mAh g-1 and 98.5% retention after 60 cycles at a current density of 0.1 A g-1 and a discharge capacity of 398 mAh g-1 even at 5 A g-1.

ZIF-67-derived Co, Ni and S co-doped N-enriched porous carbon polyhedron as an efficient electrocatalyst for oxygen evolution reaction (OER)

Rational fabrication of highly efficient and non-precious metal electrocatalysts for oxygen evolution reaction (OER) are of great importance for renewable energy exploitation to solving the energy crisis and environmental problems. In this paper, we report a novel hybrid nanostructure with Co, Ni and S co-doped N-enriched porous carbon polyhedron (CoNixSy/NCP) via a absorption-pyrolysis-sulfuration strategy derived from zeolitic imidazolate framework-67 (ZIF-67) and explored its electrocatalytic performance for OER. During the synthesis process, Ni2+ is abosrbed within the pores or surface of ZIF-67 and Ni/ZIF-67 can be transformed into the Co and Ni co-doped porous carbon frameworks when it is sulfurazed at 800 °C. NiS2 and NiCo2S4 nanoparticles formed at high temperature are homogeneously dispersed in porous carbon and can activate its electrocatalytic performance. The porous carbon can enhance the electrochemical surface area and charge transfer efficiency. Benefiting from the synergistic effects between highly active NiS2, NiCo2S4, and porous carbon, CoNixSy/NCP electrocatalyst exhibits excellent electrocatalytic performance. The results show that CoNixSy/NCP also exhibits a potential as low as 1.51 V to achieve 10 mA/cm2 current density and extremely stability towards OER. The good electrocatalytic activity of CoNixSy/NCP further suggest its great potential as an efficient eletctocatalyst for sustainable energy applications.

Decorating Cu2O photocathode with noble-metal-free Al and NiS cocatalysts for efficient photoelectrochemical water splitting by light harvesting management and charge separation design

Developing low-cost but effective cocatalyst is of crucial importance for strongly enhancing the photoelectrodes performance in photoelectrochemical (PEC) water splitting. Herein, we firstly report a rational and low-cost design of a ternary photocathode that Cu2O sandwiched by spatial noble-metal-free cocatalysts (NiS nanoparticles on the surface and Al nanoparticles on the bottom) to realize enhanced PEC performance. The integration of Al with surface plasmon resonance (SPR) effect and electron trapper NiS spatially loaded on the Cu2O nanocubes is indeed conducive to excite the hot electron-hole pairs, boost the solar light absorption and elevate ultrafast spatial transfer and separation of photogenerated electrons and holes, resulting in remarkable photocurrent density of −5.16 mA/cm2 at 0 V vs. RHE, an eight-fold enhancement than that of pristine Cu2O. The selection of noble-metal-free Al and NiS cocatalysts is superior substitute to noble metal Au and Pt from the comparison with our previous work. Therefore, this work could inspire ongoing interest in the design of highly efficient and cost-effective hybrid photoelectrodes which is able to replace noble metals in practical applications of PEC water splitting.

NiS2 Nanoparticles with Tunable Surface Area As Catalyst for Ethanol Oxidation

NiS2 is rationally and readily prepared via a simple and general hydrothermal synthetic route. The particle sizes of NiS2 species are tunable by adjusting the pH value of the hybrid solution. The optimized sample (NiS2-4) contains NiS2 nanoparticles of about 32.6 nm, and large surface area of 368.5 m2 g–1. The high surface area renders NiS2-4 an excellent electrocatalytic performance for ethanol oxidation. NiS2-4 electrode also exhibits a good long-term cycling stability. 93.3% of the initial current density is recovered by moving the NiS2-4 electrode into fresh 0.1 M NaOH solution with 0.5 M ethanol after 500 cycles. The excellent electrocatalytic properties of NiS2-4 for ethanol oxidation stems from the high surface areas.

Electrospun carbon nanofiber-encapsulated NiS nanoparticles as an efficient catalyst for hydrogen production from hydrolysis of sodium borohydride

Carbon nanofibers (CNFs) incorporating NiS nanoparticles (NPs), namely NiS@CNFs were prepared by one-step electrospinning and successfully employed as a catalyst for hydrogen production from hydrolytic dehydrogenation of sodium borohydride (SBH). As-prepared NiS@CNFs, composed of polyacrylonitrile (PAN), nickel acetate, and ammonium sulfide, was calcined at 900 °C in argon atmosphere, and characterized using standard surface science techniques. The combined results revealed the growth of NiS NPs inside the CNFs, hence confirmed the presence of elemental Ni, S, and C. The as-prepared NiS@CNFs catalyst has a significantly higher surface area (650.92 m2/g) than the reported value of 376 m2/g. Importantly, this catalyst exhibited a much higher catalytic performance, for H2 production from SBH, than that of Ni@CNFs, as evidenced by its low activation energy (∼25.11576 kJ/mol) and their Rmax values of 2962 vs. 1770 mL/g·min. Recyclability tests on using NiS@CNFs catalyst showed quantitatively production (∼100% conversion) of H2 from SBH and retained up to 70% of its initial catalytic activity after five successive cycles. The low cost and high catalytic performance of the designed NiS@CNFs catalyst enable facile H2 production from readily available hydrogen storage materials.

Porous and Hierarchically Structured Ammonium Nickel Molybdate/Nickel Sulfide/Reduced Graphene Oxide Ternary Composite as High Performance Electrode for Supercapacitors

AbstractA novel ternary composite composed of ammonium nickel molybdate, nickel sulfide and reduced graphene oxide (ANM‐NiS‐rGO) has been synthesized by using a two‐step hydrothermal method for the first time. The morphological analysis reveals that the rGO nanosheets in the ternary composite are decorated with the electrochemically active NiS nanoparticles and ANM microflowers. Because the ternary composite exhibits a porous and 3D flower‐like structures, it possesses the large surface area of 135 m2 g−1 and high pore volume of 0.258 cm3 g−1. On the other hand, ANM‐NiS‐rGO was investigated as positive electrode for battery‐type hybrid supercapacitor that shows a specific capacity of 150 mAh g−1 at a current density of 1 A g−1. For comparison, the corresponding components such as ANM‐rGO and NiS‐rGO were also investigated. It was found that the ternary composite shows a higher specific capacity, better rate capability and cyclic stability compared with the binary composites as the former possesses higher surface area and electrical conductivity. To demonstrate the practical applications, a hybrid supercapacitor was fabricated by using ANM‐NiS‐rGO and rGO as the positive and negative electrodes, respectively. This device can be operated in the voltage range of 0–1.75 V and shows a high specific capacity of 28 mAh g−1 at a current density of 2 Ag−1. Furthermore, the device delivers a maximum energy density of 24.2 Wh kg−1 at a power density of 1.75 kW kg−1. These results suggest that the porous and hierarchically structured ANM‐NiS‐rGO has high potential in practical energy storage applications.