NiCo2 S4 Research Articles

One stone, three birds: The enhanced electrocatalytic sensing for 4-nitrophenol derived from the triple-strategies regulated interface of Co-ZIF-L/NCS/CP

4-nitrophenol (4-NP) is one of the most toxic organic pollutants, which causes severe damages to organism and environment. The electrochemical analysis for 4-NP proceeded slowly due to the hard electrocatalytic reduction of 4-NP, the limited catalytic sites and poor stability of the electrodes. In this paper, by the “one stone with three birds” strategy, a series of three-phase interfaces n-Co-ZIF-L/NCS-X/CP were constructed for the enhanced electrocatalytic sensing for 4-NP. By the dual in-situ strategy, NiCo2S4 (NCS) was first electrodepositing on carbon paper (CP) and then Co-based metal-organic framework (Co-ZIF-L) was grown on the NiCo2S4, which not only introduced abundant metal active sites, but also improved the interfacial stability due to the strong bond interactions; By the dual-regulation strategy, the structures and composites of NiCo2S4 and Co-ZIF-L were precisely regulated. The heterogeneous structure of lamellar and nanoflower-like NiCo2S4, as well as the two-dimensional leaf-like Co-ZIF-L, made more catalytic sites be exposed and improved the electrocatalytic activity; The triple synergistic effect among Co-ZIF-L, NiCo2S4 and CP effectively optimized the electronic structure of the interfacial active sites and widen the electron transport channels, thus accelerated the electrochemical sensing process. In addition, the three-phase interface of 0.3-Co-ZIF-L/NCS-20/CP was successfully applied for 4-NP detection in the practical samples of lake water, seawater and industrial wastewater.

Binderless Electrodeposited NiCo2S4-MWCNT as a Potential Anode Material for Sodium-Ion Batteries

Conversion type ternary NiCo2S4, exhibiting high electrical conductivity (∼1.25 × 106 S m−1) and high theoretical capacity (703 mAh g−1), has gained interest as an anode material for sodium-ion batteries (SIBs). Despite its potential, NiCo2S4 (NCS) has extensive volume expansion during cycling. This study introduces the NCS-multi-walled carbon nanotube (MWCNT) onto a carbon fiber (CF) electrode (NCS and NCS-MWCNT@CF), developed through electrodeposition, which addresses these limitations. The unique sheet-like morphology of NCS, featuring abundant pores, ensures good access to the electrolyte. Incorporating a three-dimensional conductive CF framework that acts as a free-standing current collector helps prevent the agglomeration of NCS particles and mitigates volume expansion by providing enough buffer space in the layers of the CF matrix. Our findings reveal that NCS on CF electrodes deliver a second cycle capacity of 620 mA g−1 at 30 mA g−1 and retain 72% capacity after 200 cycles. At 200 mA g−1, the NCS@CF electrodes deliver 378 mAh g−1 in the second cycle with 68% capacity retention in the 200th cycle, whereas NCS-MWCNT@CF delivers 538 mAh g−1 at 200 mA g−1, maintaining 86 % capacity after 100 cycles, making it a potential anode for SIBs.

Construction of S-doped cellulose nanocrystals with edge sulfur vacancies to enhance the generation of 1O2 and promote peroxymonosulfate (PMS) activation

The strategy of constructing edge sulfur vacancies at cellulose surface interfaces has attracted widespread interest in fields such as electronics, photonics, optoelectronics, electrocatalysis, environmental remediation, and biosensing. In this study, NiCo2S4 (NCS) was modified onto cellulose sulfide nanocrystals (SCNC) with chiral helical structures. Utilizing high energy β Particle bombardment on the surface of photocatalysts induces the generation of edge S vacancies in SCNC, while promoting the formation of heterometallic single-atom clusters (Con, Nin) in NCS. The edge sulfur vacancies on the surface of SCNC exhibit high reactivity and adsorption capacity. The aggregation of Co and Ni at this position can transfer photo generated electrons to the edge sulfur vacancies, thereby protecting the edge sulfur vacancies and prolonging the carrier lifetime. Electrons enriched in edge S vacancies can activate the O–O bond of PMS, thereby achieving efficient degradation of ciprofloxacin (CIP). The degradation kinetics constant of Con-Nin/NCS/SCNC-Sv/PMS is 1.69 times higher than that of NCS/SCNC/PMS. In addition, electron paramagnetic resonance (EPR) shows that the sample produces a large amount of 1O2 during photocatalysis This article constructs a new approach for protecting edge S vacancies with heterogeneous single atom clusters, providing a new perspective for achieving efficient photocatalytic degradation of CIP.

N-doped lotus seedpods biocarbon hybridized with NiCo2S4 as counter electrodes for dye sensitized solar cells

A facile and green approach to composites containing nitrogen doped lotus seedpods biocarbon (NALC) and NiCo2S4 (NCS) is reported. The composites present excellent electrocatalytic activity for reduction from I3− to I− due to the synergistic effect between the nanocrystalline NCS and the NALC. Dye-sensitized solar cells (DSSCs) assembled with the as-prepared NALC@NCS counter electrodes (CEs) achieve impressive photovoltaic conversion efficiency (PCE) of 8.58%, which is higher than that by the same structured cell with Pt (7.85%) and NCS (7.53%) CEs. Compared with other NCS based CEs, the NALC@NCS CEs show good durability and stability, suggesting that combining nanocrystalline catalyst with biocarbon is beneficial to stimulate the synergistic effect, and is a feasible strategy to optimal CEs for high performance DSSCs. Low cost NALC@NCS composites developed in this work are environmentally friendly, stable and efficient, which are believed to be good candidates for Pt-free CE materials in DSSCs and electrocatalysis applications.

Construction of Nickel Molybdenum Sulfide/Black Phosphorous 3D Hierarchical Structure Toward High Performance Supercapacitor Electrodes.

Supercapacitors (SCs) with outstanding versatility have a lot of potential applications in next-generation electronics. However, their practical uses are limited by their short working potential window and ultralow-specific capacity. Herein, the facile one-step in-situ hydrothermal synthesis is employed for the construction of a NiMo3S4/BP (black phosphorous) hybrid with a 3D hierarchical structure. After optimization, the NiMo3S4/BP hybrid displays a high specific capacitance of 830 F/g at 1 A/g compared to the pristine NiMo3S4 electrode. The fabricated NiMo3S4/BP//NiCo2S4/Ti3C2Tx asymmetric supercapacitor exhibits a better specific capacitance of 120 F/g at 0.5 A/g, which also demonstrates a high energy density of 54 Wh/kg at 1148.53 W/kg and good cycle stability with capacity retention of 86% and 97% of Coulombic efficiency after 6000 cycles. Further from the DFT simulations, the hybrid NiMo3S4/BP structure shows higher conductivity and quantum capacitance, which demonstrate greater charge storage capability, due to enhanced electronic states near the Fermi level. The lower diffusion energy barrier for the electrolyte K+ ions in the hybrid structure is facilitated by improved charge transfer performance for the hybrid NiMo3S4/BP. This work highlights the potential significance of hybrid nanoarchitectonics and compositional tunability as an emerging method for improving the charge storage capabilities of active electrodes.

High-performance supercapacitor based on NiCo2S4/g-C3N4/polyaniline deposited on carbon cloth for structural stability

Although the synthesis of NiCo2S4(NCS)/g-C3N4(GCN)/PANI as an electroactive material has been extensively documented, assembling a Nickel cobalt sulfide (NCS) electrode with outstanding electrochemical efficiency at high current density is still difficult. In this work, the fabrication of a supercapacitor (Sc) electrode of petal-like NiCo2S4/g-C3N4/PANI using a hydrothermal, thermal condensation, and chemical oxidative polymerization method was done. In this nanocomposite, g-C3N4 stabilized the metal atoms and PANI integration considerably improves ion mobility, leading to rapid charge transmission. Due to improvement in electron mobility, the eventual NiCo2S4/g-C3N4(0.40wt%) /PANI(A-3) electrode had shown a specific capacitance (Cs) of 3.4 F/cm2 (1799.07 F/g) with 90% retention and 2700 cycles at the current density of 2 mA/cm2. A good rate capacity of 87.36% at 5 mA/cm2, 82.92% at 10 mA/cm2, and a 50.35% decline of its original capacitance at a high charge/discharge current density of 20 mA/cm2. This work demonstrates that the produced NiCo2S4/g-C3N4/PANI electrode has a high potential for use in energy storage gadget technologies.

Construction of multi-interface PDA-NiCo2S4 nanomaterials for synergistic design of efficient microwave absorption and anti-corrosion effects

The modern and complex environment requires microwave absorbing materials (MAMs) that can cope with environmental changes. In particular, the high humidity, high salt spray and high temperature of the marine environment conditions have been the toughest. Consequently, the development of integrated materials with both microwave absorption (MA) and corrosion resistance has emerged as a top priority. In this work, spherical NiCo2S4 (NCS) particles with stable size were prepared by a simple solvothermal method. Furthermore, the self-polymerization of dopamine (PDA) on the surface of NCS was achieved by exploiting the film-forming ease of dopamine. A series of PDA-NCS particles with different interfaces were fabricated by tuning the ratio of NCS and dopamine. The integrated magneto-electric drive synergy enhances the impedance matching. Multiple heterogeneous interfaces enhance the depletion efficiency of electromagnetic waves (EMWs) within the material. The samples designed have achieved an effective absorption bandwidth (EAB) value of 6.26 GHz and a maximum reflection loss value of −22 dB at a low thickness of 1.7 mm. Meanwhile, due to the electrochemical protection reaction of anode of metal and the passivation effect of barrier by PDA. The prepared coatings maintained favorable corrosion resistance in 240 h of continuous salt spray environment. Moreover, after the 240 h salt spray experiment, the sample realized the EAB value of 4.77 GHz at a thickness of 1.7 mm. This work breaks new ground for the development of absorbing and anti-corrosion integrated materials.

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.

Optimization of sodium storage performance by structure engineering in nickel-cobalt-sulfide.

The development of high-performance electrode materials is crucial for the advancement of sodium ion batteries (SIBs), and NiCo2S4 has been identified as a promising anode material due to its high theoretical capacity and abundant redox centers. However, its practical application in SIBs is hampered by issues such as severe volume variations and poor cycle stability. Herein, the Mn-doped NiCo2S4@GNs composite electrodes with hollow nanocages were designed using a structure engineering method to relieve the volume expansion and improve the transport kinetics and conductivity of the NiCo2S4 electrode during cycling. Physical characterization and electrochemical tests, combined with Density functional theory (DFT) calculations indicate that the resulting 3% Mn-NCS@GNs electrode demonstrates excellent electrochemical performance (352.9 mA h g-1 (200 mA g-1) after 200 cycles, and 315.3 mA h g-1 (5000 mA g-1)). This work provides a promising strategy for enhancing the sodium storage performance of metal sulfide electrodes.

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.

Construction of Co9S8@NiCo2S4 core–shell hetero-nanostructure with synergistic effect of abundant mesopores and multi-metallic elements for novel high-performance flexible hybrid supercapacitors

Flexible portable supercapacitor devices have gained increasing attention in the field of energy storage in recent years. However, challenges remain in the selection of applicable flexible materials and/or the preparation of materials. Through our research, we have effectively constructed a flexible CS@NCS/CC core–shell hetero-nanostructured cathode material by anchoring Co9S8 (CS) nanopins on a flexible carbon cloth (CC) substrate firstly, and then wrapping NiCo2S4 (NCS) nanosheets on the outer surface of CS nanopins. In this process, we have improved the traditional two-step method of preparing NCS nanosheets into a one-step method, which has greatly improved the efficiency of the material preparation. The prepared CS@NCS/CC material has abundant mesopores, stable core–shell heterostructures and multiple valence states of metal ions, which enable the CS@NCS/CC electrode material to have strong electrochemical reaction kinetics and excellent cycling stability. Additionally, the CC as the flexible substrate improves the charge transfer capability of the transition metal composite. Benefiting from the synergistic effect of these favorable factors, the electrode material exhibits a high Cs value of 2020.6F g−1, which maintains 89.8% after 10,000 constant current charges and discharges. It is worth noting that the CS@NCS/CC can be folded and twisted at multiple angles, which proves that it can be used in wearable applications. The flexible hybrid supercapacitor CS@NCS/CC//AC/CC displays terrific energy density (58 Wh kg−1, at 800 W kg−1) with the synergistic effect of pseudocapacitance and electrical double-layer capacitance, and a capacitance retention rate of 92.9% after 10,000 cycles of constant current charging and discharging. Therefore, using CC as the flexible substrate and transition metal sulphides as the active material is an effective strategy for constructing high-performance flexible supercapacitors.

Defect-engineered Sulfur Vacancy Modified NiCo2 S4-x Nanosheet Anchoring Polysulfide for Improved Lithium Sulfur Batteries.

The low conductivity of sulfur and the shuttle effect of lithium polysulfides (LiPSs) are the two intrinsic obstacles that limit the application of lithium-sulfur batteries (LSBs). Herein, a sulfur vacancy introduced NiCo2 S4 nanosheet array grown on carbon nanofiber (CNF) membrane (NiCo2 S4-x /CNF) is proposed to serve as a self-supporting and binder-free interlayer in LSBs. The conductive CNF skeleton with a non-woven structure can effectively reduce the resistance of the cathode and accommodate volume expansion during charge-discharge process. The bonding between CNF matrix and NiCo2 S4 nanosheet is enhanced by in situ growth, ensuring fast electron transfer. Besides, the sulfur vacancies in NiCo2 S4 enhance the chemisorption of LiPSs, and the highly active sites at vacancies can accelerate the LiPSs conversion kinetics. LSB paired with NiCo2 S4-x /CNF interlayer achieved improved stability in 500 cycles at 0.2 C and long life of 3000 cycles at 3 C. More importantly, a high areal capacity of 9.69 mAh cm-2 is achieved with a sulfur loading of 10.8mg cm-2 and a low electrolyte to sulfur (E/S) ratio of 4.8. This work provides insight into the sulfur vacancy in catalysis design for LiPSs conversion and demonstrates a promising direction for electronic defect engineering in material design for LSBs.

Amorphous Oxysulfide Reconstructed from Spinel NiCo2S4 for Efficient Water Oxidation

The progress of effective and durable electrocatalysts for oxygen evolution reaction (OER) is urgent, which is essential to promote the overall efficiency of green hydrogen production. To improve the performance of spinel cobalt-based oxides, which serve as promising water oxidation electrocatalysts in alkaline electrolytes, most researches have been concentrated on cations modification. Here, an anionic regulation mechanism is employed to adopt sulfur(S)anion substitution to supplant NiCo2 O4 by NiCo2 S4 , which contributed to an impressive OER performance in alkali. It is revealed that the substitution of S constructs a sub-stable spinel structure that facilitates its reconstruction into active amorphous oxysulfide under OER conditions. More importantly, as the active phase in the actual reaction process, the hetero-anionic amorphous oxysulfide has an appropriately tuned electronic structure and efficient OER electrocatalytic activity. This work demonstrates a promising approach for achieving anion conditioning-based tunable structure reconstruction for robust and easy preparation spinel oxide OER electrocatalysts.

Electrolyte Engineering on Performance Enhancement of NiCo2 S4 Anode for Sodium Storage.

NiCo2 S4 is an attractive anode for sodium-ion batteries (SIBs) due to its high capacity and excellent redox reversibility. Practical deployment of NiCo2 S4 electrode in SIBs, however, is still hindered by the inferior capacity and unsatisfactory cycling performance, which result from the mismatch between the electrolyte chemistry and electrode. Herein, a functional electrolyte containing 1.0m NaCF3 SO3 in diethylene glycol dimethyl ether (DEGDME) (1.0m NaCF3 SO3 -DEGDME) is developed, which can be readily used for NiCo2 S4 anode with high initial coulomb efficiency (96.2%), enhanced cycling performance, and boosted capacities (341.7mA h g-1 after 250 continuous cycles at the current density of 200mA g-1 ). The electrochemical tests and related phase characterization combined with density functional theory (DFT) calculation indicate the ether-based electrolyte is more suitable for the NiCo2 S4 anode in SIBs due to the formation of a stable electrode-electrolyte interface. Additionally, the importance of the voltage window is also demonstrated to further optimize the electrochemical performance of the NiCo2 S4 electrode. The formation of sulfide intermediates during charging and discharging is predicted by combining DFT and verified by in situ XRD and HRTEM. The findings indicate that electrolyte engineering would be an effective way of performance enhancement for sulfides in practical SIBs.

Carbon Encapsulated NiCo2 S4 Nanoparticles with Enhanced Surface Mediated Charge Storage for Superior Ultracapacitor Electrodes.

Three different compositions of NiCo2 S4 (NCS) materials were prepared using three solvents, named NCS HTDI (hydrothermal in DI water), NCS STEG (solvothermal in ethylene glycol), and a novel carbon-encapsulated NCS STFA (solvothermal in formamide). The structural and morphological properties of the prepared NCS HTDI, NCS STEG, and NCS HTDI materials were analyzed using various physical characterization techniques. As prepared, NCS materials were tested as an electrode for supercapacitor (SC) application using a 3-electrode system in a basic electrolyte (3 M KOH). NCS HTDI exhibits a specific capacitance of 2536 F g-1 , NCS STEG shows 1355 F g-1 , and NCS STFA shows 1178 F g-1 at an input current density of 1 A g-1 . The SBN-PSC material is utilized as a counter electrode in the NCS STFA || SBN-PSC-based asymmetric SC device. The device exhibits exceptionally superior electrochemical performance with a specific capacitance of 172 F g-1 at 10 A g-1 input current density and 97% capacity retention after 5000 cycles in a voltage window of 1.6 V. The results confirm the superiority of NCS STFA||SBN-PSC deviceas an excellent high-energy and high-power SC.

Investigation of Biomass-Derived Heteroatom-Doped Carbon Fiber Aerogel Decorated with NiCo2S4 Flowers as a Binder-Free Anode for Urea Electrooxidation: From a Sustainable Standpoint

The fabrication of proficient anodes for urea oxidation reaction (UOR) with the inherent traits including competent catalytic activity, enhanced electronic conductivity, sound durability, and low cost are the inevitable criteria for the advancement and practical implementation of green energy conversion devices, such as direct urea/urine fuel cells. Herein we are reporting the decoration of biomass-derived nitrogen-doped carbon fiber aerogel (NCFA) with three-dimensional (3D) flower-like NiCo2S4 (NCS) architectures fabricated via the one-step hydrothermal method and exploited as a binder-free anode for UOR. With concrete operational stability, the constructed NCS@NCFA (1:2) anode delivered an excellent current density of 166 mA cm–2 and 79 mA cm–2 in urea and human urine, respectively. This remarkable UOR activity of the NCS@NCFA (1:2) electrode is chiefly ascribed to the unique 3D open morphological feature, which triggers the maximum adsorption and momentous electrooxidation of urea. Moreover, the densely interconnected graphitized fibers not only inhabit the catalytic active structures but also facilitate the elevated anolyte transfer characteristics by their conductive open framework.

Dual regulation strategy to enhance the electrochemical performance of rich sulfur vacancies NiCo2S4 integrate electrode material for supercapacitors

NiCo2S4 is a promising electrode material for supercapacitors due to its high conductivity and rich elemental valence distribution. However, the low specific capacitance and poor cycling stability of NiCo2S4 electrode material restricted its practical application. In this paper, we proposed a dual regulation strategy of nitrogen-doped carbon cloth current collector (NCC) and the introduction of S vacancies in the NiCo2S4 (NCS) to prepare a high electrochemical performance of integrated electrode material. The introduction of N doping into the CC current collector helped to improve the loading capacity of NCS and contributed to capacitance, while the rich S vacancies in NCS could provide more electroactive sites and increase its electrical conductivity. Benefiting from the synergistic effect of NCC and S vacancies, the fabricated NCS4–0.5/NCC integrated electrode material illustrated an ultra-high specific capacitance of 4075.89 mF cm−2 (2079.53 F g−1) at 1 mA cm−2 and superior electrochemical cycling stability with 80.03% of initial capacitance at a high current density of 20 mA cm−2 after 5000 cycles. Therefore, the present dual regulation strategy provides a new route to fabricate supercapacitor electrode materials with excellent electrochemical properties.

Rationally Designed Bimetallic Co-Ni Sulfide Microspheres as High-Performance Battery-Type Electrode for Hybrid Supercapacitors.

Rational designing of electrode materials is of great interest for improving the performance of battery-type supercapacitors. The bimetallic NiCo2S4 (NCS) and CoNi2S4 (CNS) electrode materials have received much attention for supercapacitors due to their rich electrochemical characteristics. However, the comparative electrochemical performances of NCS and CNS electrodes were never studied for supercapacitor application. In this work, microsphere-like bimetallic NCS and CNS structures were synthesized via a facile one-step hydrothermal method by controlling the molar ratio of Ni and Co precursors. The physico-chemical results confirmed that microsphere-like structures with cubic spinel-type NCS and CNS materials were successfully fabricated by this method. When tested as the supercapacitor electrode materials, both NCS and CNS electrodes exhibited battery-type behavior in a three-electrode configuration with outstanding electrochemical performances such as specific capacity, rate performance and cycle stability. Impressively, the CNS electrode delivered a high specific capacity of 430.1 C g-1 at 1 A g-1, which is higher than 345.9 C g-1 of the NCS electrode. Furthermore, the NCS and CNS electrodes showed a decent cycling stability with 75.70 and 84.70% capacity retention after 10,000 cycles. Benefiting from the electrochemical advantage of CNS microspheres, we fabricated a hybrid supercapacitor (HSC) device based on CNS microspheres (positive electrode) and activated carbon (AC, negative electrode), which is named as CNS//AC. The assembled CNS//AC HSC device showed a large energy density of 41.98 Wh kg-1 at a power density of 800.04 W kg-1 and displayed a remarkable cycling stability with a capacity retention of 91.79% after 15,000 cycles. These excellent electrochemical performances demonstrate that both bimetallic NCS and CNS microspheres may provide potential electrode materials for high performance battery-type supercapacitors.

Accelerating the reaction kinetics from nitrate to ammonia by anion substitution in NiCo-based catalysts

The electrocatalytic nitrate reduction reaction (NITRR) plays a critical role in maintaining global nitrogen balance, which is strongly depended on the reactive activity of catalysts. Herein, we develop a simple hydrothermal technology to replace the O ions in NiCo2O4 (NCO) by S ions to form NiCo2S4 (NCS), in which the bonding interactions among Ni-O or Co-O bonds are stronger than Ni-S and Co-S bonds. Therefore, more 3d electrons can be localized at Ni or Co sites that can donate more charges to the intermediates. As a result, the ammonia yield can be enhanced to 642 μg h−1 cm−2 and the selectivity can reach 92.42%, which is obviously excellent than NCO. This work provides a new insight into accelerating the electrocatalytic activity by regulating the orbital interaction between anions and cations.

Surface Spin Enhanced High Stable NiCo2 S4 for Energy-Saving Production of H2 from Water/Methanol Coelectrolysis at High Current Density.

Nickel based materials are promising electrocatalysts to produce hydrogen from water in alkaline media. However, the stability is of great challenge, limiting its practical material functions. Herein, a new technique for electro-deposition flower-like NiCo2 S4 nanosheets on carbon-cloth (CC@NiCo2 S4 ) is proposed for energy-saving production of H2 from water/methanol coelectrolysis at high current density by constructing array architectures and regulating surface magnetism. The optimized and fine-tuned magnetism on the surface of the electrochemical in situ grown CC@NiCo2 S4 nanosheet array result in (0 1 -1) surface universally exposed, high catalytic activity for methanol electrooxidation, and long-term stability at high current density. X-ray photoelectron spectroscopy in combination of density functional theory calculations confirm the valence electron states and spin of d electrons for the surface of NiCo2 S4 , which enhance the surface stability of catalysts. This technology may be utilized to alter the surface magnetism and increase the stability of Ni-based electrocatalytic materials in general.