NiCo2S4 Nanoparticles Research Articles

A highly sensitive and selective label-free impedimetric immunosensor for the detection of interleukin-6 based on AuNPs@pDA@NiCo2S4@MoS2 nanocomposite.

A highly sensitive and selective label-free impedimetric immunosensor based on AuNPs@pDA@NiCo2S4@MoS2 nanocomposite modified on the surface of a screen-printed electrode (SPE) was designed for the detection of interleukin-6 (IL-6). The distribution of NiCo2S4 nanoparticles on MoS2 nanosheets was able to prevent them from agglomerating. The polydopamine (pDA) layer was coated on the surface of NiCo2S4@MoS2 nanosheets by self-polymerization, which improved the stability and biocompatibility of the nanomaterial. The excellent reduction ability of pDA promoted the synthesis of gold nanoparticles (AuNPs), which increased the amount of antibody adsorption and the conductivity of the material. Finally, the antibody (Ab) of IL-6 was immobilized on the surface of AuNPs@pDA@NiCo2S4@MoS2 nanocomposite. Electrochemical impedance spectroscopy (EIS) was used to detect the change of impedance before and after the immune response between Ab and IL-6 antigen (IL-6). Under the optimal experimental conditions, the relative change in impedance and the logarithmic concentration of IL-6 showed a good linear relationship in the range 1.00 to 1.00 × 106pg/mL, with a low detection limit of 0.97pg/mL. In addition, the proposed immunosensor performed with good reproducibility, stability, and specificity. It was successfully applied to the determination of IL-6 in patient's serum samples of head and neck carcinoma with recoveries of 98.40% to 106.5%. To sum up, the proposed label-free impedimetric immunosensor was successfully constructed for IL-6 detection in real samples.

NiCo2S4 nanoparticles encapsulated within hollow mesoporous carbon spheres enabling rapid and stable sodium storage

Poor rate capability and cycling performance significantly impair the utilization of NiCo2S4 as an anode material in sodium-ion batteries. Herein, hollow mesoporous carbon spheres (HMCSs) are synthesized using a hard-template method. NiCo2S4 nanoparticles with sizes ranging from 15 to 43 nm are grown in-situ within HMCSs (NiCo2S4@HMCS) by melt adsorption, solution impregnation, and gas-phase sulfurization. Specifically, NiCo2S4 nanoparticles are uniformly distributed on the inner walls of HMCSs and within the mesoporous channels of spherical shells. In half-cells, NiCo2S4@HMCS exhibits reversible capacities of 482 mAh g−1 after 340 cycles at 1.0 A g−1, 340 mAh g−1 after 600 cycles at 5.0 A g−1, and 271 mAh g−1 after 700 cycles at 10.0 A g−1. In NiCo2S4@HMCS//Na3V2(PO4)3 full-cells, NiCo2S4@HMCS maintain reversible capacities of 203 mAh g−1 after 1200 cycles at 1.0 A g−1 and 122 mAh g−1 after 2000 cycles at 5.0 A g−1. The unique nano-encapsulated structure prevents the detachment of NiCo2S4 from HMCSs, maintaining electrochemical activity and stability of NiCo2S4. Additionally, the nano-encapsulated structure also facilitates electrolyte penetration and enhances the electronic conductivity of NiCo2S4. These effects synergistically result in rapid and stable sodium storage performance.

Design and fabrication of reduced graphene oxide (RGO) incorporated NiCo2S4 hybrid composites as electrode materials for high performance supercapacitors

One of the most promising bimetallic sulphides for use in energy-storage systems is NiCo2S4, but further research is required to give it a high reversibility and electrochemical reaction capacity. In this study, we show the rational materials design of an ideal NiCo2S4 nanoparticle as a NiCo2S4/RGO nanocomposite, embedded in a reduced graphene oxide (RGO) matrix. NiCo2S4 nanoparticles, which ranged in size from 20 to 25 nm and were firmly fixed on the surface of RGO sheets, made up the produced composite. As predicted, the produced nanocomposite displayed a high specific surface area, a mesoporous structure, and high conductivity, resulting in a large electroactive area and rapid electron and ion motion. Additionally, we present the advancements in material science, showcasing the NiCo2S4/RGO nanocomposite electrode, which has a long cycle life of 5000 cycles, a high capacitance retention of 85.6 %, and an exceptional specific capacitance of 1505 Fg-1 at 1 Ag-1. A high active-material loading asymmetric supercapacitor serves as an example of the real-world use. The NiCo2S4/RGO nanocomposite exhibits an exceptional 48 Whkg-1 energy density at a power density of 985 Whkg-1, while maintaining a high power density of 7227 Wkg-1 density of 25 Whkg-1. The exceptional stability and electrochemical efficiency of the NiCo2S4/RGO nanocomposite validate that our methodical materials science and technology optimisation in the areas of active substance synthesis, electrode expansion, and device design/fabrication will help advance the development of high-performance supercapacitors in future years.

Synthesis and Characterization of NiCo2S4-MOF-ZIF-67@rGO for Efficient Electrochemical Energy Storage

Abstract A nanocomposite, NiCo2S4-MOF-ZIF-67@reduced grapheme oxide was produced via a straightforward and scalable hydrothermal process. The product nanocomposite was characterized using different techniques including Infra red spectroscopy, X-ray diffraction analysis, scanning electron microscopy and electrochemical measurements. This nanocomposite was found to be composed of NiCo2S4 nanoparticles embedded in a MOF-ZIF-67 matrix, which was anchored onto rGO sheets. The NiCo2S4-MOF-ZIF-67@rGO nanocomposite exhibited excellent electrochemical performances. These properties make the NiCo2S4-MOF-ZIF-67@rGO nanocomposite a potential electrode substance in the case of electric energy accumulators and conversion devices such as primary and rechargeable Li cells and high performance ultra-capacitors. The simple and scalable synthesis method used in this study also suggests that this material has potential for large-scale production.

Tunable fabric zinc-based batteries utilizing core-shell like fiber electrodes with enhanced deformation durability

One-dimensional (1D) fiber-based batteries stand as a promising route for next-generation wearable devices, owing to their combined energy storage capability and wearability. However, the development of efficient fiber electrodes and high-quality battery configurations that retain excellent electrochemical performance and garment compatibility while withstanding variable mechanical deformations remains a pressing challenge. In this study, NiCo2S4@rGO nanocomposites with stable structures and excellent electrochemical performance were constructed using an in-situ hydrothermal strategy. The highly conductive network of reduced graphene oxide (rGO) improved the electron transport efficiency of the nanocomposites, while mitigating volume changes, structural collapse, and self-aggregation of NiCo2S4 nanoparticles during the charging/discharging cycle. As expected, the nanocomposite cathodes in the Zn-based batteries exhibited remarkable discharging capacity (277.11 mAh g−1) and cycling performance (70% retention after 2000 cycles). Subsequently, a composite fiber cathode (NiCo2S4@rGO-PU-CNTs) with tailorable length and core-shell like structure was fabricated via wet spinning. Benefiting from the introduced carbon nanotubes (CNTs) and polyurethane (PU), the composite fiber cathode formed efficient dual-conducting networks and stable core-shell like structures, thereby improving the electron transport pathways and mechanical flexibility. Finally, as a proof of concept, the independent NiCo2S4@rGO-PU-CNTs cathode and independent Zn@SSY (stainless steel yarn) anode were woven into a knitted fabric, creating tunable serpentine footprint fabric Zn-based batteries with exceptional electrochemical properties (175.29 mAh g−1 and 0.088 mAh cm−1), coupled with remarkable electrochemical stability and mechanical deformation durability. The engineering strategy reported herein provides a promising platform for the quick, facile, and continuous preparation of composite fiber cathodes and tailorable wearable energy textiles.

Mesoporous NiCo2S4@rGO nanocomposites as sulfur carriers for high performance lithium sulfur batteries

It is of unprecedented significance to surmount the daunting challenges of lithium-sulfur battery due to its low cost and exceptionally high energy density. Herein, the mesoporous NiCo2S4@rGO nanocomposites were fabricated solvothermally with mesoporous NiCo2S4 nanoparticles dispersed on rGO and investigated as highly-efficient carriers for sulfur cathode in lithium-sulfur battery. The as-obtained NiCo2S4@rGO nanocomposites are featured with abundant mesopore, good electronic and ionic conductivity, excellent catalytic effect on the redox of lithium polysulfides conversion and strong adsorption, thus observably accelerating the redox kinetics of lithium polysulfides and suppressing the shuttle effect. Therefore, the NiCo2S4@rGO@S electrode delivers a high reversible specific discharge density of 785 mAh g−1 at 0.1 C after 100 cycles and exhibits good rate capability and cycling stability, verifying its great promising for the commercial application of lithium-sulfur battery.

Construction of hierarchical NiCo2 S4 /2D-Carbyne nanohybrid onto nickel foam for high performance supercapacitor and non-enzymatic electrochemical glucose sensor applications.

Synthesising and designing pseudocapacitive material with good electrochemical and electrocatalytic behaviour is essential to use as supercapacitor as well as non-enzymatic glucose sensor electrode. In this work, NiCo2 S4 nanoparticles decorated onto the 2D-Carbyne nanosheets are achieved by the solvothermal process. The as-prepared NiCo2 S4 @2D-Carbyne provides rich reaction sites and better diffusion pathways. On usage as an electrode for supercapacitor application, the NiCo2 S4 @2D-Carbyne exhibits the specific capacitance of about 2507 F g-1 at 1 A g-1 . In addition, the fabricated hybrid device generates an energy density of 52.2 Wh kg-1 at a power density of 1.01 kW kg-1 . Besides, the glucose oxidation behaviour of NiCo2 S4 @2D-Carbyne modified GCE has also been performed. The diffusion of glucose from the electrolyte to the electrode obeys the kinetic control process. Furthermore, the fabricated NiCo2 S4 @2D-Carbyne non-enzymatic glucose sensor exhibits a limit of detection of about 34.5 μM with a sensitivity of about 135 μA mM-1 cm-2 . These findings highlight the need to design and synthesis electrode materials with adequate electrolyte-electrode contact, strong structural integrity, and rapid ion/electron transport.

In‐Situ Colloidal Synthetic Route to Monodispersed NiCo2S4 Nanoparticles over Nickel Foam for High‐Performance Supercapacitive Charge Storage

AbstractOne‐step colloidal synthetic route was adopted to in‐situ grow monodispersed NiCo2S4 nanoparticles (NPs) on nickel foam (NF) from metallic salts with benzyl disulfide in the media of oleylamine and octadecene. Owing to the favorable dispersion and considerable redox activity of NiCo2S4 along with tight and binder‐free connection with NF, the obtained battery‐type supercapacitor delivered a specific capacitance of 1790.8 F g−1 at 1 A g−1 via a three‐electrode system. Simultaneously, it just degraded 40 % at 20 A g−1 and maintained 86.8 % of initial specific capacitance (C0) after 2000 cyclic trials at 10 A g−1. When the NiCo2S4 NPs were assembled with active carbon (AC) forming an asymmetric capacitor device of NiCo2S4 NPs//AC, it delivered an energy density (E) of 48.7 W h kg−1 at a power density (P) of 161.1 W kg−1, and kept 21.9 W h kg−1 at a high P of 8.05 kW kg−1. Meanwhile, the capacitor manifested preeminent cycling life (C=94.5 % C0 after 5000 cyclic trials) at 5 A g−1. The in‐situ grown NiCo2S4 NPs on NF without any binder exhibited high performance in energy storage, providing a feasible way to improve the electrochemical performance of the electrode materials.

Novel Surface-Enriched Spiky Ball With Spines NiCo2S4@GO/CNT Electrode Material for a High-Performance Flexible Asymmetric Supercapacitor

Nickel cobalt sulfide (NiCo2S4) nanoparticles on graphene oxide GO sheets and carbon nanotube (CNT) were fabricated successfully via a simple solvothermal route. Most NiCo2S4 nanoparticles cover both sides of the GO sheets, and the carbon nanotubes are arranged at the edge of the composite, creating a Spiky ball structure that effectively prevents the accumulation of GO. Synthesized hybrid nanocomposite (NiCo2S4/GO/CNT) has an optimum specific surface area and pore nature, and the coupling between CNT and GO enhances the electrochemical properties of NiCo2S4. The structural, morphological, and spectral characteristics were analysed using diffraction, microscopy, and spectroscopy techniques. To determine the electrochemical activity, cyclic voltammetry (CV), galvanostatic charge-discharge spectroscopy, and electrochemical impedance spectroscopy (EIS) were performed in a 3 M KOH electrolyte solution, the prepared sample was evaluated as an active electrode material for the supercapacitor. It delivers a very high specific capacitance of 845 Fg−1 at a current density of 2 Ag −1 as compared with NiCo2S4 (423 Fg−1). Coin cell was fabricated and tested using NiCo2S4/GO/CNT as cathode and graphite as an anode. The device exhibited an excellent energy density of 30.8 Wh kg−1, a power density of 3691 Wkg−1, and good cyclic stability with 82% retention after 1000 cycles.

Self-supporting hierarchical porous NiCo2S4/RGO/CNTs nanohybrids with abundant exposed electroactive redox sites for excellent hybrid supercapacitor

Bimetallic sulfide NiCo2S4 is a highly promising electrode material for applications in novel sustainable high-performance energy storage devices, but its poor rate capability and cycling life need to be enhanced. Herein, we report a novel self-supporting hierarchical porous NiCo2S4/RGO/CNTs nanohybrids (NCSRCs) by co-modification of NiCo2S4 nanoparticles with RGO and CNTs. The synergistic effect of RGO and CNTs not only constructs a hierarchical porous conductive network that facilitates charge transport kinetic and ion diffusion kinetic, but also provides abundant induced sites for the dispersion anchoring of NiCo2S4 nanoparticles due to their high specific surface area with rich functional groups, which reduces the stacking of NiCo2S4 nanoparticles and provides abundant exposed electroactive redox sites. Therefore, the electrochemical performance test results demonstrate that the NCSRCs electrodes exhibit significantly enhanced charge storage performance, showing a high specific capacity of 257.1 mAh g−1 at 0.3 A g−1 and good rate capability. In addition, the optimal NCSRC-24//N-RGO aqueous hybrid supercapacitor delivered a high specific energy of 33.67 Wh kg−1 and ultra-long durability with 82.44% capacity retention after 22,000 cycles. These results provide a facile approach to design and synthesize novel NCSRCs nanohybrids with superior properties for high-safety, sustainable and efficient aqueous energy storage devices.

In Situ XPS Proved Efficient Charge Transfer of S‐Scheme Heterjunction Based on Graphdiyne (g‐CnH2n‐2) Nanosheets Coupling with Semi‐Crystalline NiCo2S4 for Efficient Photocatalytic H2 Evolution

AbstractThe excessive utilization of fossil fuels has resulted in an energy crisis. The implementation of a heterojunction for photocatalytic hydrogen evolution represents a promising solution to the current energy predicament. In this work, a 0D/2D S‐scheme graphdiyne/NiCo2S4 (GDY/NiCo2S4) heterojunction is constructed by semi‐crystalline NiCo2S4 nanoparticles (NPs) immobilized on the surface of GDY nanosheets through hydrothermal method. Atomic force microscopy (AFM) demonstrated the thickness of GDY nanosheets is 2.8 nm. The unique 2D laminar structure and porous structure of GDY ensures a tight bond with NiCo2S4 NPs. The maximum rate of photocatalytic hydrogen production is 6682.6 µmol h−1 g−1 over 15% GDY/NiCo2S4, which is much higher than GDY and NiCo2S4. The outstanding photocatalytic hydrogen production performance can be attributed to the S‐scheme GDY/NiCo2S4 heterostructure. The fluorescence results demonstrated that the incorporation of GDY significantly enhanced the efficiency of photoelectron‐hole transfer and prolonged the electron lifetime. The S‐scheme photogenerated charge transfer mechanism is verified through in situ irradiated X‐ray photoelectron spectroscopy. The present study introduces innovative concepts for the design of an S‐scheme heterojunction based on graphdiyne, aiming to enhance photocatalytic hydrogen production.

Electrochemical phase evolution of NiCo2S4 nanoparticles in aqueous alkaline electrolyte

Evaluating structural stability of electrode materials under electrochemical operation in the alkaline electrolyte needs to further clarify, which is closely related with the electrochemical mechanism. Herein, NiCo2S4 nanoparticles@CNT sponge was prepared as the working electrode in three-electrode test system. From the first 20th CV test procedure, specific capacitances with the range of 1034 ∼ 1344F/g show electrochemical reversibility. Intriguingly, NiCo2S4 nanoparticles have not only stacked into nanosheets, and but also separated from the surface of the CNT sponge. Spinel NiCo2S4 nanoparticles have first partially cracked into the metastable derivative phases of Ni(Co)OOH, Ni(OH)2, and then quickly converted into the mixed hexagonal NiOOH and cubic Co3S4. S atoms disengage from the lattice positions of spinel NiCo2S4 nanoparticles, which depicts the irreversible electrochemical reaction occurring during electrochemical operation process.

Enhanced pseudocapacitive behaviour in laser-written graphene micro-supercapacitors decorated with nickel cobalt sulphide nanoparticles

The next generation of energy storage technologies requires enhanced fabrication techniques such as the use of CO2 infrared lasers to pattern micro-supercapacitor (MSC) electrodoes. This study reports direct-writen laser-induced graphene (LIG) micro-supercapacitors with electrodepositated NiCo2S4- nanoparticles on commercial polyimide sheets. X-ray photoelectron spectroscopy (XPS) combined with transmission electron microscopy (TEM) showed NiCo2S4 nanoparticles decorating the graphene, within a highly porous carbon-based electrode. The LIG/NiCo2S4 exhibited outstanding properties with a specific capacitance of 30.4 mF cm−2 at 0.75 mA cm−2 and an energy density of 16.9 µWh cm−2 at a power density of 367.5 µW cm−2. High capacitance retention of 1.22-fold was measured after 5000 cycles of charge/discharge, and of ∼90% when bent to 120˚ angle. Here, it is demonstrated that surface decoration is an effective route in improving LIG MSC storage properties, and that the LIG/NiCo2S4 MSC is suitable for use in next generation of flexible and miniaturized portable devices.

Fabrication of super-high energy density asymmetric supercapacitor prototype device employing NiCo2S4@f-MWCNT nanocomposite

Materials with high porosity, high redox activity and rich electrochemically active sites are promising candidates for pseudocapacitance. Among the bimetallic sulphides of transition metals, nickel cobalt sulphide (NiCo2S4; NCS) is a promising pseudocapacitive material. NiCo2S4 (NCS) can be coupled with carbonaceous material such as functionalised multiwalled carbon nanotubes (NCS@f-MWCNT) to further enhance the electrochemical characteristics such as high charge-storage capacity, improved charge-discharge characteristics, stability and rate performance. In this line, bare NiCo2S4 (NCS) and functionalized multiwalled carbon nanotubes (f-MWCNT) loaded NiCo2S4 nanoparticles were synthesized by hydrothermal method by employing hexadecyltrimethylammonium bromide (CTAB) as surfactant. X-ray diffraction studies confirmed the formation of cubic phase of NiCo2S4 and transmission electron microscopic study revealed the formation of NCS@f-MWCNT nanocomposite. The XPS findings confirmed the co-existence of Ni3+, Ni2+, Co3+, and Co2+ species in both the NCS and NCS@f-MWCNT samples. Cyclic voltammetry analysis was performed to determine the respective impacts of the surface adsorption and diffusion-mediated processes on the charging/discharging kinetics. The incorporation of f-MWCNT into NCS led to improved overall charge storage kinetics, demonstrating a promising avenue for developing low-cost cathode materials for high-performance hybrid battery-type materials with both high power and energy densities. Bare NiCo2S4 showed a specific capacitance of ~899 Fg−1 at 1 Ag−1 with a capacitance retention of ~52 %. While NCS@f-MWCNT exhibited a high charge storage capacity of ~1360 Fg−1 with capacitance retention of 89 % at 10 Ag−1. An asymmetric coin cell devices were fabricated using NCS@f-MWCNT as a positive electrode and an activated carbon, reduced graphene oxide ((ASC2) or carbon fiber (ASC3) as negative electrodes. Among them, the NCS@f-MWCNT//AC (say ASC1) showed outstanding charge storage characteristics with a capacitance of ~109.9 Fg−1, energy density ~ 78.3 Whk g−1 and power density ~ 800 Wk g−1 at 1Ag−1. The presented analysis has demonstrated that a hybrid structure made of highly conductive materials like functionalized multiwall carbon nanotubes could be employed to synergistically enhance the electrochemical performance of NiCo2S4.

Hybridization of graphene into NiCo2S4 hybrid composites as electrode materials for high performance supercapacitors

NiCo2S4 is one of the most promising bimetallic sulfides for use in energy-storage systems, but more studies are needed to endow NiCo2S4 (NCS) with a high electrochemical reaction capability and reversibility. In this work, we present rationally materials design of an optimal NiCo2S4 nanoparticle in a graphene (G) matrix as a NiCo2S4/graphene nanocomposite (NCSG). A uniform composite with NiCo2S4 nanoparticles anchored on graphene sheets is fabricated through an innovative one-step hydrothermal method. The XRD, Raman, XPS, SEM, HRTEM and EDS analyses are performed for characterizing the morphology and microstructure of the as-prepared NiCo2S4/graphene composite. Furthermore, we report the improvements in the materials technology, demonstrating the NiCo2S4/graphene (NCSG) nanocomposite electrode with an excellent specific capacitance of 1500 Fg−1 at 2 Ag−1, high capacitance retention of 85.6 %, and long cycle life of 6500 cycles. The practical application is showcased in an asymmetric supercapacitor with a high active-material loading. Tremendously, the produced NiCo2S4/AC asymmetric supercapacitor has a high energy density of 43.2 Wh kg−1 at a power density of 920 W kg−1.

Hollow Spherical NiCo2S4@N-CNT Composites with High Energy Density for All-Solid-State Supercapacitors

NiCo2S4@N-CNT composites with multidimensional hierarchical structures are rationally designed and synthesized by a simple two-step hydrothermal strategy, aiming to achieve excellent electrochemical performances for supercapacitor applications. The hollow spherical NiCo2S4 nanoparticles with both zero- and two-dimensional architecture are interconnected by the conductive bridges of nitrogen-doped carbon nanotubes (N-CNTs, 1D). This unique structure can provide a much rougher surface, rich two-phase interface, and porous channels exposed to electrolytes with fast ion diffusions and electron transmissions, as well as effectively relieve the expansion/contractions during charging and discharging. As such, the asymmetric all-solid-state supercapacitor device assembled by NiCo2S4@N-CNTs and activated carbons can provide an energy density high up to 59.37 W h kg–1 at the power density (750 W kg–1). Even if the power density is increased up to 1.5 kW kg–1, it still can achieve the energy density superior to 45.6 W h kg–1. These results can provide the open interesting perspective to design the favorable structure of bimetallic sulfides for supercapacitor applications.

NiCo2S4 combined 3D hierarchical porous carbon derived from lignin for high-performance supercapacitors

Metal sulfides with the nature of low electronegativity and high electrochemical activity are potentially considered effective electrode materials for supercapacitors. Meanwhile, hierarchical porous carbon (HPC) materials derived from eco-friendly enzymatic hydrolysis lignin are the ideal matrix for holding nanoparticles (NP) that allows the overall NP/HPC composite to achieve outstanding electrochemical performance. In this study, NiCo2S4 nanoparticles were in-situ synthesized on the inner surface of 3D HPC that derived from enzymatic hydrolysis lignin with a simple one-step solvothermal method, thus forming a high-performance composite electrode material for supercapacitor applications. As a result, the NiCo2S4/HPC composite yields an outstanding specific capacity of 1264.2 F g−1 at 1 A g−1 and also exhibits remarkable rate performance. Such remarkable property is attributed to the effective combination of NiCo2S4 plus HPC and their strong chemical bonds, which enable excellent electronic conductivity and abundant exposed electroactive sites. The asymmetric supercapacitor assembled by utilizing NiCo2S4/HPC and active carbon as the positive and negative electrodes, respectively, provide an excellent energy density of 32.05 Wh kg−1 at a power density of 193.9 W kg−1. This work puts forward a practical optimization strategy for metal sulfides used in electrochemical energy storage devices.

NiCo2S4 nanoparticles anchored in the 3D interpenetrating framework composed of GNs and CNTs toward enhanced sodium storage performance

NiCo2S4 as a promising anode material for sodium ion batteries (SIBs) with rich redox potential and high theoretical specific capacity, but suffers the poor conductivity and severe volume expansion. The electrode materials with a three-dimensional (3D) framework can facilitate the migration of ions/electrons, enhance structural stability, and alleviate the volume expansion during charging/discharging. Herein, we report the NiCo2S4 nanoparticles anchored on a 3D interpenetrating framework consisting of graphene nanosheets (GNs) and carbon nanotubes (CNTs) to solve the above issues. Benefiting from the structural stability and superior conductivity in special 3D structure, the as-prepared NCS@GNs@CNTs electrode delivers a high initial discharge/charge capacity (558.1/538.8 mAh g1 at 100 mA g−1), superior cyclic stability (362.8 mAh g−1 after 100 cycles at 200 mA g−1) and an excellent rate capability (311.8 mAh g−1 at 5000 mA g−1). Furthermore, the sodium-ion full-cell Na3V2(PO4)3@C-NCS@GNs@CNTs test demonstrates that NCS@GNs@CNTs exhibits good cycling stability and further illustrates the possibility in practical applications.

Superdispersed NiCo2S4 nanoparticles anchored on layered C3N4 for high performance supercapacitor

In recent years, the concept of sustainable development has encouraged the development and application of green, natural, and recyclable energy storage devices. Herein, using Ni(NO3)20.6 H2O and Co(NO3)20.6 H2O as raw material and K2S2O8 as a vulcanizing agent, NiCo2S4 nanomaterials@C3N4 (NCS@C3N4) composite was prepared by a one-step solvothermal method, in which the introduction of C3N4 significantly improves the dispersion of NCS, while the petal-like NCS also expands the layer spacing of C3N4, which effectively alleviates the structural instability and promotes the exposure of stable active sites during charge and discharge. Physical structure and electrochemical characterizations showed that the NCS were distributed on the surface of the C3N4 nanosheets, which reduced the stacking of the nanosheets and accelerated the charge transfer during the charging and discharging process. The specific capacity (Csp) of the NCS@C3N4 composite electrode was up to 890.4 C/g at a current density of 1 A/g. In addition, the supercapacitor consisting of NCS@C3N4 composite electrode had good cycling stability and still displayed excellent capacitance retention after 3000 cycles. The NCS@C3N4 composite greatly optimizes the stability and extends the operating life of supercapacitors, which has a broad application potential in the field of energy storage devices.

Superdispersed NiCo2S4 nanoparticles anchored on reduced graphene oxide for efficient hydrogen evolution reaction in acidic and alkaline media

Reasonable design and preparation of the earth abundant and efficient electrocatalysts for hydrogen production from the electrolysis of water is an effective solution to solve the growing global energy and environmental crisis. Herein, in order to increase the number of the active sites and fasten the charge transfer of NiCo 2 S 4 , a facile two-step solvothermal method is used to prepare superdispersed NiCo 2 S 4 nanoparticles anchored on reduced graphene oxide (NCS/rGO) as low-cost and high-efficient electrocatalyst for hydrogen evolution reaction (HER). By modulating the amount of rGO, the as-prepared NCS/rGO composite shows high specific surface area of 114.4 m 2 g −1 and small particle size of 50–60 nm, which exhibits excellent HER activity with a lower overpotential of 115 mV at 10 mA cm −2 and a smaller charge transfer resistance of 12 Ω in acidic solution. Additionally, in the case of alkaline solution, the as-prepared NCS/rGO composite also exhibits a low overpotential of 241 mV and a small Tafel slope of 110 mV dec −1 . The significantly improved HER performance of NCS/rGO composite can be ascribed to the constructed heterogeneous interface between NiCo 2 S 4 nanoparticles and rGO, which can inhibit the aggregation of NiCo 2 S 4 nanoparticles and enhance the intrinsic electrical conductivity. In light of the excellent HER electrocatalytic performance, the inexpensive NCS/rGO composite might be regarded as a promising alternative in HER and other energy conversion and storage applications. • Superdispersed bimetallic NiCo 2 S 4 nanoparticles anchored on rGO are obtained via a friendly solvothermal method. • The conductive graphene can avoid the agglomeration of NiCo 2 S 4 nanoparticles and facilitate the conduction of electrons. • The NiCo 2 S 4 /rGO composite possesses high specific surface area and provides rich active sites for HER. • The resulting NiCo 2 S 4 /rGO composite achieves enhanced HER activities in acidic and alkaline media.