Ni3S2 Nanosheet Arrays Research Articles

Interface engineering of Ag-Ni3S2 heterostructures toward efficient alkaline hydrogen evolution.

Exploring Earth-abundant transition-metal-based electrocatalysts with high performance toward the alkaline hydrogen evolution reaction (HER) is crucial for sustainable hydrogen production. Ni3S2 has been recently identified as a promising HER catalyst, but it has unfavorable water dissociation and hydrogen adsorption characteristics. Here, we report Ag-decorated Ni3S2 nanosheet arrays grown on Ni Foam (NF) (Ag-Ni3S2/NF) as efficient heterostructure electrocatalysts for the HER in alkaline media. The catalyst only requires a low overpotential of 89 mV at 10 mA cm-2, as well as sustaining long-term durability for 15 h. The experimental analysis, in combination with density functional theory calculation, demonstrates that the electronic coupling at the interface between Ni3S2 and Ag results in enhanced electronic conductivity and optimized hydrogen adsorption and water adsorption/dissociation free energies. This work not only develops a highly efficient catalyst toward the HER, but also sheds light on the structure-activity relationship of the heterostructure catalyst on an atomic scale.

Vanadium doping over Ni3S2 nanosheet array for improved overall water splitting

Abstract Engineering 3D dual-functional electrodes with non-noble metals toward efficient overall water electrolysis is significantly important but challenging for the renewable chemical fuels. Here, vanadium doped Ni3S2 nanosheets array decorated on carbon fiber cloth (V-Ni3S2/CC) is successfully constructed as 3D dual-functional electrodes for efficient overall water splitting. The specific nanosheet array electrode provides structural benefits of high contact area, abundant accessible catalytic sites, shortened and accelerated charge transfer, and improved electrolyte penetration. Moreover, the vanadium dopants have a positive effect on the catalysis process, contributing to the improved intrinsic activity and accelerated catalysis reaction kinetics of Ni3S2 catalyst. Reasonably, the developed V-Ni3S2/CC electrodes exhibit robust water splitting performances, with small overpotential of 180 mV for oxygen evolution reaction and 81 mV for hydrogen evolution reaction at 10 mA cm−2. In a V-Ni3S2/CC dual-electrodes constructed electrolyzer system, an ultralow cell potential of 1.49 V is achieved for a stable catalytic current of 10 mA cm−2, outperforming most of the reported non-noble metals based dual-functional electrocatalysts.

Electronic modulation of composite electrocatalysts derived from layered NiFeMn triple hydroxide nanosheets for boosted overall water splitting.

Herein, we report the synthesis of Fe and Mn co-doped Ni3S2 nanosheet arrays (FM-NS NSAs) as well as layered NiFeMn triple hydroxide (NiFeMn-LTH)/FM-NS hybrid NSAs (HNSAs) via an easily controllable sulfidation method with NiFeMn-LTH NSAs as the precursor, which can be employed as coupled oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) electrodes to achieve boosted overall water splitting performance. It is discovered that the incorporation of the dual Fe and Mn cations can simultaneously modulate the morphology and optimize the electron density of the obtained catalysts. As a result, the full sulfidation product of FM-NS NSAs display a much-enhanced activity for the OER at a current density of 10 mA cm-2 with an overpotential of 188 mV. The NiFeMn-LTH/FM-NS HNSAs obtained from partial sulfidation demonstrate an enhanced HER activity with a lower overpotential of 110 mV at 10 mA cm-2. The FM-NS NSA anode and the NiFeMn-LTH/FM-NS HNSA cathode were coupled in an alkaline medium for overall water splitting and exhibited a much lower cell voltage of 1.48 V at 10 mA cm-2, superior to most of the reported noble-metal-free electrocatalysts. Additionally, a battery-assisted electrolyzer (1.5 V) was assembled to explore the feasibility for practical energy-efficient water splitting.

One-step electrodeposition fabrication of Ni3S2 nanosheet arrays on Ni foam as an advanced electrode for asymmetric supercapacitors

Ni3S2 nanosheet (NS) arrays on Ni foam were fabricated by a simple one-step electrodeposition strategy, and used as a kind of electrode material for asymmetric supercapacitors. The Ni3S2 NS arrays are interconnected, which can be regarded as bridges between these individual nanoparticle units. The electrochemical performances were evaluated by cyclic voltammetry and chronopotentiometry techniques in a three-electrode system. The Ni3S2 NS arrays display a specific capacitance of 773.6 F g−1 at 1 A g−1, and excellent rate property of 84.3% at 10 A g−1. The performance of the Ni3S2 NS arrays was further investigated in an asymmetric supercapacitor for potential practical application. The asymmetric supercapacitor using the Ni3S2 electrode and reduced graphene oxide electrode as positive and negative electrodes, respectively, exhibits an energy density of 41.2 W h kg−1 at 1.6 kW kg−1. When up to 16 kW kg−1, it holds 25.3 W h kg−1. These excellent electrochemical performances are attributed to the improved electronic conductivity and rich redox reaction sites from Ni3S2 NS arrays. Our results indicate that the Ni3S2 NS arrays have great potential for supercapacitors.

Nickel sulfide wrapped by porous cobalt molybdate nanosheet arrays grown on Ni foam for oxygen evolution reaction and supercapacitor

Co-Mo-O (Co1.2MoO4.2·1.3H2O)/Ni3S2 nanosheet arrays were in-situ grown directly on Ni foam (NF) by a facile two-step hydrothermal reaction, in which the untrathin Co-Mo-O nanosheets are connected to each other into a three-dimensional (3D) porous hierarchical architecture with Ni3S2 entrapped on the underneath Ni support. The resulting Co-Mo-O/Ni3S2/NF exhibits an excellent electrocatalytic activity for oxygen evolution reaction (OER) in KOH solution, which yields a 50 mA cm−2 of OER current density at an overpotential of 0.29 V, outperforming the state-of-the-art noble RuO2 (η50 = 0.42 V), Co-Mo-O/NF (η50 = 0.33 V) and Ni3S2/NF (η50 = 0.31 V). And it demonstrates a high specific capacity of 340 mAh g−1 at 2 mA cm−2 with good capability (82.1% of the retention at 32 mA cm−2) in basic solution when used as supercapacitor electrode, which is superior to those of Co-Mo-O/NF (183 mAh g−1) and Ni3S2/NF (70 mAh g−1). The outstanding electrochemical performance of Co-Mo-O/Ni3S2/NF is associated with the synergistic effect of the individual components as well as the nanosheets directly grown on Ni conducting support with more active sites exposed. Furthermore, Co-Mo-O/Ni3S2/NF displays good durability in 12 h-electrolysis experiment for OER and 10000 charge-discharge cycles. It is expected to benefit from Ni3S2 entrapped by the protective layer of 3D porous Co-Mo-O nanosheet arrays, which not only can provide channel for electrolyte ion to pass through, but also improve the stability of Ni3S2. In addition, the fabricated Co-Mo-O/Ni3S2/NF//Activated carbon (AC) asymmetrical supercapacitor shows an ultra-high energy density of 57.9 Wh kg−1 at a power density of 1.1 kW kg−1.

Honeycomb-like Ni3S2 nanosheet arrays for high-performance hybrid supercapacitors

Supercapacitors have attracted great attention as advanced energy storage devices. However, the low energy density and high cost of electrode materials are the downsides for their practical applications. Here, we introduce a facile and low-cost strategy to develop honeycomb-like Ni3S2 nanosheet arrays (NSAs) as a redox-type electrode for aqueous hybrid supercapacitors (HSCs). Owing to the porous structure of NSAs, the Ni3S2 electrode can show excellent electrochemical performance in 2 M KOH aqueous electrolyte. A high specific capacity of 151.2 mAh g−1 has been achieved at the current density of 3 A g−1. To demonstrate their further applications, HSCs have been assembled with activated carbon (AC) as negative electrode and the assembled devices can successfully work within a large voltage range of 0–1.6 V and deliver a maximum energy density of 35.2 Wh kg−1 at the power density of 491 W kg−1.

Anion Engineering on 3D Ni3S2 Nanosheets Array toward Water Splitting

Anion engineering on transition-metal-based materials has been put forward as an important strategy to develop efficient and stable non-noble-metal electrocatalysts toward water electrolysis, including both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). On the basis of theoretical predictions, a three-dimensional (3D) integrated electrode constructed by P-decorated Ni3S2 nanosheet arrays (Ni3S2|P) was prepared via a facile two-step method. The suitable controlled incorporation of P anions into the Ni3S2 matrix can have little influence on the crystal structure, and meanwhile can effectively modify the electronic structure, increase the concentration of charge carrier, supply more delocalized electrons, facilitate more active sites to be electrically activated, optimize the hydrogen adsorption Gibbs free energy, strengthen the interaction for water molecules, and benefit the oxidation of Ni2+ to Ni3+ oxo-/hydroxides. As a result, the freshly achieved 3D Ni3S2|P electrode exhibits hi...

Enhanced Catalysis of Electrochemical Overall Water Splitting in Alkaline Media by Fe Doping in Ni3S2 Nanosheet Arrays

The development of bifunctional electrocatalysts with high performance for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with earth-abundant elements is still a challenge in electrochemical water splitting technology. Herein, we fabricated a free-standing electrocatalyst in the form of vertically oriented Fe-doped Ni3S2 nanosheet array grown on three-dimensional (3D) Ni foam (Fe-Ni3S2/NF), which presented a high activity and durability for both HER and OER in alkaline media. On the basis of systematic experiments and calculation, the Fe-doping was evidenced to increase the electrochemical surface area, improve the water adsorption ability, and optimize the hydrogen adsorption energy of Ni3S2, which resulted in the enhancement of HER activity on Fe-Ni3S2/NF. Moreover, metal sites of Fe-Ni3S2/NF were proved to play a significant role in the HER process. During the catalysis of OER, the formation of Ni–Fe (oxy)hydroxide was observed on the near-surface section of Fe-Ni3S2/NF, and...

Ultrafast surface modification of Ni3S2 nanosheet arrays with Ni-Mn bimetallic hydroxides for high-performance supercapacitors

Amorphous Ni-Mn bimetallic hydroxide film on the three-dimensional nickle foam (NF)-supported conductive Ni3S2 nanosheets (denoted as Ni-Mn-OH@Ni3S2/NF) is successfully synthesized by an ultrafast process (5 s). The fascinating structural characteristic endows Ni-Mn-OH@Ni3S2/NF electrodes better electrochemical performance. The specific capacitance of 2233.3 F g−1 at a current density of 15 A g−1 can achieve high current density charge and discharge at 20/30 A g−1 that the corresponding capacitance is 1529.16 and 1350 F g−1, respectively. As well as good cycling performance after 1000 cycles can maintain 72% at 15 A g−1. The excellent performance can be attributed to unique surface modification nanostructures and the synergistic effect of the bimetallic hydroxide film. The impressive results provide new opportunity to produce advanced electrode materials by simple and green route and this material is expected to apply in high energy density storage systems.

Ultrafast Formation of Amorphous Bimetallic Hydroxide Films on 3D Conductive Sulfide Nanoarrays for Large‐Current‐Density Oxygen Evolution Electrocatalysis

Developing nonprecious oxygen evolution electrocatalysts that can work well at large current densities is of primary importance in a viable water-splitting technology. Herein, a facile ultrafast (5 s) synthetic approach is reported that produces a novel, efficient, non-noble metal oxygen-evolution nano-electrocatalyst that is composed of amorphous Ni-Fe bimetallic hydroxide film-coated, nickel foam (NF)-supported, Ni3 S2 nanosheet arrays. The composite nanomaterial (denoted as Ni-Fe-OH@Ni3 S2 /NF) shows highly efficient electrocatalytic activity toward oxygen evolution reaction (OER) at large current densities, even in the order of 1000 mA cm-2 . Ni-Fe-OH@Ni3 S2 /NF also gives an excellent catalytic stability toward OER both in 1 m KOH solution and in 30 wt% KOH solution. Further experimental results indicate that the effective integration of high catalytic reactivity, high structural stability, and high electronic conductivity into a single material system makes Ni-Fe-OH@Ni3 S2 /NF a remarkable catalytic ability for OER at large current densities.

Efficient electrocatalysis of overall water splitting by ultrasmall NixCo3−xS4 coupled Ni3S2 nanosheet arrays

The overall water splitting into hydrogen and oxygen is one of the most promising ways to store intermittent solar and wind energy in the form of chemical fuels. However, this process is quite thermodynamically uphill, and thus needs to be mediated simultaneously by efficient hydrogen evolving and oxygen evolving catalysts to get any feasible output from it. Herein, we report the synthesis of such a catalyst comprising ultrasmall NixCo3−xS4-decorated Ni3S2 nanosheet arrays supported on nickel foam (NF) via a partial cation exchange reaction between NF-supported Ni3S2 nanosheet arrays and cobalt(II) ions. We show that the as-prepared material, denoted as NixCo3−xS4/Ni3S2/NF, can serve as a self-standing, noble metal-free, highly active and stable, bifunctional electrocatalyst for the two half reactions involved in the overall water splitting: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Furthermore, we demonstrate that a high-performance electrolyzer for the overall water splitting reaction can be assembled by using NixCo3−xS4/Ni3S2/NF as the electrocatalyst at both the cathode and the anode sides of the electrolyzer. This electrolyzer delivers water-splitting current densities of 10 and 100mA/cm2 at applied potentials of 1.53 and 1.80V, respectively, with remarkable stability for >200h in both cases. The electrolyzer's performance is much better than the performances of electrolyzers assembled from many types of other bifunctional electrocatalysts as catalyst couple. Moreover, the overall performance of the electrolyzer is comparable with the performances of electrolyzers containing two different, benchmark, monofunctional HER and OER electrocatalyst couple (i.e., Pt/C-IrO2).

A Zn-doped Ni3S2 nanosheet array as a high-performance electrochemical water oxidation catalyst in alkaline solution.

It is of high importance to design efficient electrocatalysts for the oxygen evolution reaction (OER) at alkaline pH. In this communication, we report the development of a Zn-doped Ni3S2 nanosheet array on Ni foam (Zn-Ni3S2/NF) as a high-performance and durable electrocatalyst for the OER. Such Zn-Ni3S2/NF drives a catalytic current density of 100 mA cm-2 with the requirement of an OER overpotential of 330 mV, 90 mV less than that for Ni3S2/NF. Furthermore, Zn-Ni3S2/NF demonstrates excellent long-term electrochemical durability maintaining its activity at an overpotential of 300 mV for 20 h.

Rational Design of Self-Supported Ni3S2 Nanosheets Array for Advanced Asymmetric Supercapacitor with a Superior Energy Density.

We report a rationally designed two-step method to fabricate self-supported Ni3S2 nanosheet arrays. We first used 2-methylimidazole (2-MI), an organic molecule commonly served as organic linkers in metal-organic frameworks (MOFs), to synthesize an α-Ni(OH)2 nanosheet array as a precursor, followed by its hydrothermal sulfidization into Ni3S2. The resulting Ni3S2 nanosheet array demonstrated superior supercapacitance properties, with a very high capacitance of about 1,000 F g-1 being delivered at a high current density of 50 A g-1 for 20,000 charge-discharge cycles. This performance is unparalleled by other reported nickel sulfide-based supercapacitors and is also advantageous compared to other nickel-based materials such as NiO and Ni(OH)2. An asymmetric supercapacitor was then established, exhibiting a very stable capacitance of about 200 F g-1 at a high current density of 10 A g-1 for 10,000 cycles and a surprisingly high energy density of 202 W h kg-1. This value is comparable to that of the lithium-ion batteries, i.e., 180 W h kg-1. The potential of the material for practical applications was evaluated by building a quasi-solid-state asymmetric supercapacitor which showed good flexibility and power output, and two of these devices connected in series were able to power up 18 green light-emitting diodes.

High-Index Faceted Ni3S2 Nanosheet Arrays as Highly Active and Ultrastable Electrocatalysts for Water Splitting

Elaborate design of highly active and stable catalysts from Earth-abundant elements has great potential to produce materials that can replace the noble-metal-based catalysts commonly used in a range of useful (electro)chemical processes. Here we report, for the first time, a synthetic method that leads to in situ growth of {2̅10} high-index faceted Ni3S2 nanosheet arrays on nickel foam (NF). We show that the resulting material, denoted Ni3S2/NF, can serve as a highly active, binder-free, bifunctional electrocatalyst for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Ni3S2/NF is found to give ∼100% Faradaic yield toward both HER and OER and to show remarkable catalytic stability (for >200 h). Experimental results and theoretical calculations indicate that Ni3S2/NF's excellent catalytic activity is mainly due to the synergistic catalytic effects produced in it by its nanosheet arrays and exposed {2̅10} high-index facets.

3D Ni3S2nanosheet arrays supported on Ni foam for high-performance supercapacitor and non-enzymatic glucose detection

3D Ni3S2 nanosheet arrays grown on Ni foam were successfully synthesized through a facile one-step hydrothermal approach and then directly applied as the electrode for a high-performance supercapacitor and non-enzymatic glucose sensor. The structure and morphology of the prepared Ni3S2 were characterized by X-ray power diffraction (XRD), field emission scanning electronic microscopy (FESEM) and transmission electron microscopy (TEM). The subsequent electrochemical measurements showed that the Ni3S2 nanosheet array electrode possessed a superior specific capacitance of 1370.4 F g−1 at a current density of 2 A g−1. Remarkably, a specific capacitance of 952.0 F g−1 could be still achieved at a high current density of 20 A g−1, indicating its excellent rate capability. And 91.4% of the specific capacitance was retained after 1000 cycles at a current density of 6 A g−1. Besides, to demonstrate its practical application, an asymmetric supercapacitor based on the Ni3S2 nanosheet array electrode as the positive electrode and activated carbon as the negative electrode was assembled. It delivered high energy density and good long-term stability. Additionally, serving as a non-enzymatic sensor, the 3D Ni3S2 nanosheet array electrode exhibited remarkable electrocatalytic activity towards glucose oxidation with a high sensitivity of 6148.0 μA mM−1 cm−2. All these impressive performances suggest that the Ni3S2 nanosheet array is a promising electrode material for supercapacitors and non-enzymatic glucose sensors.