Binary Transition Metal Sulfides Research Articles

Nanostructured binary transition-metal-sulfides and nanocomposites as high-performance electrodes for hybrid supercapacitors

Supercapacitors (SCs) are attractive as promising energy storage devices because of their distinctive attributes, such as high power density, good current charge/discharge ability, excellent cyclic stability, reasonable safety, and low cost. Electrode materials play key roles in achieving excellent performance of these SCs. Among them, binary transition metal sulfides (BTMSs) have received significant attention, attributed to their high conductivity, abundant active sites, and excellent electrochemical properties. This topic review aims to summarize recent advances in principles, design, and evaluation of the electrochemical performance for nanostructured BTMSs (including nickel–cobalt sulfides, zinc–cobalt sulfides, and copper–cobalt sulfides.) and their nanocomposites (including those carbon nanomaterials, transition metal oxides, binary transition metal oxides, transition metal sulfides, and polymers). Nanostructuring of these BTMSs and nanocomposites as well as their effects on the performance were discussed, including nanoparticles, nanospheres, nanosheets, nanowires, nanorods, nanotubes, nanoarrays, and hierarchitectured nanostructures. Their electrochemical performance has further been reviewed including specific capacitance, conductivity, rate capability, and cycling stability. In addition, the performance of hybrid supercapacitors (HSCs) assembled using the nanostructured BTMSs as the cathodes also have been summarized and compared. Finally, challenges and further prospects in the HSCs-based BTMS electrodes are presented.

Binary transition metal sulfides MoS2–NiS2 anchored on biomass-derived carbon for improved performance of lithium–sulfur batteries

The poor electrical conductivity of sulfur and electrochemically active solid-state products (Li2Sn, n = 1–3), and the shuttle effect have led to the low cycling stability of lithium-sulfur batteries and the low utilization of the sulfur cathode. In this work, 3D porous biomass-derived carbon material (KMC) was prepared from Miscanthus sinensis by KOH activation. The transition metal sulfide with excellent adsorption and catalytic characteristics was effectively combined with the conductive porous biomass-derived carbon material, and a KMC/MoS2−NiS2 composite material was obtained. The product was characterized by field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Results show that MoS2−NiS2 nanoparticles can be uniformly distributed on the porous carbon material. Electrochemical measurements reveal that with an initial specific capacity of 1292 mA h g–1 at a current density of 0.1 C. After 400 cycles at 0.5 C, the specific capacity of KMC/MoS2−NiS2/S decays from 1007 to 814 mA h g–1. Thus, the capacity decay rate per cycle is about 0.054 %. This strategy provides a new idea for developing lithium−sulfur batteries with attractive performance.

The role of binary transition metal Cobalt-Nickel sulfide as an anode catalyst in specifically selection of Desulfuromonas and improved performance of microbial fuel cell

Microbial fuel cell (MFC) has been regarded as a promising approach for electricity generation by oxidizing organic wastewater, yet the low power density still hinders its factual application. By replacing oxygen with lower electronegative sulfur, the sulfide with better stability, high biocompatibility and lower internal resistance could be obtained, which is suitable for the requirements of anode materials. However, there are few studies on sulfide as anode to improve MFC from the perspective of electrochemical performance and bacteria. Hence, a capacitive and biocompatible NiCo2S4 is prepared by hydrothermal method and utilized as anode material on a titanium network in MFC. Compared with the NiCo2O4, the charge transfer resistance of the NiCo2S4 modified electrode decreases from 17.48 Ω to 8.76 Ω. Moreover, the MFC with NiCo2S4 anode obtains a faster start-up time and maximum power density of 8.40 W/m3, nearly 1.63 times higher than that of NiCo2O4 (5.13 W/m3). The microbial community analysis further exhibits that the NiCo2S4 significantly and specifically selected exoelectrogens, Desulfuromonas (42.74 %), with improved associated metabolic pathways, indicating a more efficient power generation process. The high performance could be ascribed to the fact that NiCo2S4 decreases the inner resistance and improve the efficiency and kinetics of extracellular electron transfer (EET), while its unique biocompatibility allows exoelectrogens to adhere to the bioanode selectively. This study demonstrates the potential of binary transition metal sulfide as the anode material for MFC from the perspective of electricity production and microbial community structure.

Design and regulation of FeCo2S4 nanoneedles deposited on carbon felt as binder-free electrodes for high-performance hybrid supercapacitor

Hybrid supercapacitors have drawn much attention since they possess both high energy density and power density. Carbon felt (CF) is chosen as the substrate in this work due to its 3D porous structure, good conductivity, and excellent flexibility. FeCo2S4 nanoneedles are uniformly deposited on CF via hydrothermal, annealing and sulfidation processes, forming the binder-free FeCo2S4 @CF electrode. The morphology of FeCo2S4 deposited on the CF can be designed and regulated by controlling the hydrothermal reaction time. The electrode with unique features is beneficial to the exposure of electroactive sites and the rapid transport of electrons/ions, showing a high specific capacitance of 847.8 mF cm−2 and outstanding rate performance. The hybrid supercapacitor assembled by FeCo2S4 @CF electrode and activated carbon felt exhibits the maximum specific capacitance of 309.7 mF cm−2, energy density of 110.1 μWh cm−2 and power density of 562.4 μW cm−2. Besides, the capacitance retention of the device reaches 98.5% after 10,000 charge-discharge cycles and 87.2% after 3000 bending cycles respectively, revealing its great cycling stability and flexibility. Therefore, this work provides an effective and feasible strategy for the morphology regulation of binary transition metal sulfides with superior electrochemical performance for supercapacitors.

Controlled preparation of CoNi2S4 nanorods derived from MOF-74 nanoarrays involving an exchange reaction for high energy density supercapacitors.

Binary transition metal sulfides are considered to be a promising material for supercapacitors, possessing richer electrochemically active sites and superior electrochemical performance. Metal-organic frameworks (MOFs) are often used as self-sacrificing templates in the preparation of metal sulfides. Usually, direct sulfidation of MOFs tends to cause collapse of the morphological structure and blockage of the ion transport channels, so that the morphology of the original MOF template can be well preserved by using pyrolysis followed by S2- ion exchange. In this paper, we first prepared NiCo-MOF-74 on nickel foam by an in situ transformation method from layered double hydroxides (LDHs) through a ligand exchange reaction. Then, CoNi2S4 was synthesized in two steps involving the pyrolysis of NiCo-MOF-74 and a subsequent S2- ion exchange reaction. Compared with direct sulfidation, this synthetic strategy can well maintain the rod-like morphology of MOF-74 arrays and prevent structural collapse. The surface of CoNi2S4 has a fine nanosheet structure, which exposes more active sites and shows a high specific capacitance of 7.50 F cm-2 at 2 mA cm-2 and an excellent Coulomb efficiency (96.32%). In addition, the hybrid supercapacitor assembled with activated carbon shows a high energy density of 0.64 mW h cm-2 at a power density of 1.64 mW cm-2 and a high capacitance retention of 88.39% after 5000 cycles. These results indicate that rod-shaped CoNi2S4 can be controllably prepared from MOF-74 involving an exchange reaction and has promising application in high-performance supercapacitors.

NiCo2S4 nano composite structure with high electrochemical performance in band gap

Synthesize NiCo2S4 and its application to find out electrochemical performance of anionic reaction in nano chemistry. Because of binary transition metal sulfide NiCo2S4 are prepared by using a Chemical precipitation to find out anionic movement within the compound. But the electrochemical were used as a conductive network for the NiCo2S4 hexagonal nano plates. Hence hexagonal nano plates have an average crystalline size of the particles 38.34nm and 20.06nm. Nickel and cobalt sulfides with various stoichiometries have been synthesized from Ni(CH3COO)2.2H2O, CoCl2.6H2O with different sulfur precursors using as a direct method. The morphological composite were characterized by (scanning electron microscopy) SEM, XRD (X-ray diffraction), EDX, UV-visible, FTIR spectrum and optical band-gap energy were evaluated. Optical band-gap energies in the range 4.7 eV−5.1 eV were observed.

Template strategy to synthesize porous Mn-Co-S nanospheres electrode for high-performance supercapacitors

Supercapacitors, such as pseudocapacitors (PCs), are widely used because of their excellent electrochemical activity and capacitance; however, it is still challenging to fabricate PCs with high stability and good electrochemical properties. Therefore, suitable templates and transition metal composite materials should be selected for improving their performance. Binary transition metal sulfides exhibit excellent electrochemical performance owing to their rich valence, electrical conductivity, and abundant electrochemical active sites. In this study, we prepared porous Mn-Co-S nanospheres (MCSN) via the hydrothermal method using silica colloidal particles was as the template; to the best of our knowledge, this is the first study to synthesize MCSN. Results suggest that the MCSN composite exhibited excellent conductivity and enhanced stability owing to the porous structure formed by the vertical growth of MnS2-CoS2 nanosheets on silica nanoparticles. The porous MCSN electrode showed an excellent specific capacitance of 1158 F g−1 at 1 A g−1. Moreover, when coupled with an activated carbon (AC) positive electrode, the supercapacitor of MCSN//AC exhibited stability of 90.4% after 5000 cycles at 10 A g−1 (the specific energy of 34 W h kg−1 at 775 W kg−1). Given the results, we believe that the prepared MCSN material has potential application prospects for high-efficiency supercapacitors.

Construction of a Label-Free Electrochemical Immunosensor Based on Zn-Co-S/Graphene Nanocomposites for Carbohydrate Antigen 19-9 Detection.

Nanocomposites of the binary transition metal sulfide Zn-Co-S/graphene (Zn-Co-S@G) were synthesized through a one-step hydrothermal method. They may be useful in the construction of an electrochemical immunosensor for carbohydrate antigen 19-9 (CA19-9) detection. Zn-Co-S dot-like nanoparticles uniformly covered the surface of graphene to form an interconnected conductive network, ensuring strong interaction between transition metal sulfide and graphene, which can expose numerous electroactive sites leading to the improvement of the amplified electrochemical signal toward a direct reduction of H2O2. Thus, the construction of an electrochemical immunosensor using Zn-Co-S@G nanocomposites showed outstanding sensing properties for detecting CA19-9. The constructed electrochemical immunosensor exhibited a good linear relationship in the range of 6.3 U·mL−1–300 U·mL−1, with the limit of detection at 0.82 U·mL−1, which makes it a promising candidate for an electrochemical immunosensor.

High‐performance all‐solid‐state supercapacitor with binder‐free binary transition metal sulfide array as cathode

SummaryTransition metal sulfides show excellent performance in an aqueous supercapacitor. However, all‐solid‐state supercapacitors are attracting more and more interest because of thinner, lighter, and more flexible. Binary sulfides Ni3Co6S8 nanowire arrays (NCS) are directly grown on a nitrogen‐doped carbon foam (NCF) through hydrothermal reaction, which is applied as a binder‐free electrode for all‐solid‐state supercapacitor. The unique needlelike structure assembled by nanosheet effectively increases the utilization efficiency of active materials and promotes electrochemical performance. The NCS‐NCF electrode shows promising application potential for wearable electronic devices due to the flexibility of NCF. A high‐specific capacitance of 243 mAh g−1is delivered by NCS‐NCF electrode, which also exhibits good rate behavior along with outstanding cycle stability. The NCS‐NCF electrode (positive electrode) and NCF electrode (negative electrode) are employed to assemble asymmetric all‐solid‐state supercapacitor. When the high power density is 675 W kg−1, the energy density of supercapacitor reaches the maximum of 28.31 Wh kg−1. The specific capacitance of supercapacitors could maintain 84%, after 10 000 cycles of galvanostatic charge and discharge under 4 A g−1, indicating the potential application of NCS‐NCF electrode as an excellent supercapacitor electrode material in flexible, wearable energy storage systems.

Novel Designed MnS‐MoS2 Heterostructure for Fast and Stable Li/Na Storage:Insights into the Advanced Mechanism Attributed to Phase Engineering

AbstractCombining 2D MoS2 with other transition metal sulfide is a promising strategy to elevate its electrochemical performances. Herein, heterostructures constructed using MnS nanoparticles embedded in MoS2 nanosheets (denoted as MnS‐MoS2) are designed and synthesized as anode materials for lithium/sodium‐ion batteries via a facile one‐step hydrothermal method. Phase transition and built‐in electric field brought by the heterostructure enhance the Li/Na ion intercalation kinetics, elevate the charge transport, and accommodate the volume expansion. The sequential phase transitions from 2H to 3R of MoS2 and α to γ of MnS are revealed for the first time. As a result, the MnS‐MoS2 electrode delivers outstanding specific capacity (1246.2 mAh g−1 at 1 A g−1), excellent rate, and stable long‐term cycling stability (397.2 mAh g−1 maintained after 3000 cycles at 20 A g−1) in Li‐ion half‐cells. Superior cycling and rate performance are also presented in sodium half‐cells and Li/Na full cells, demonstrating a promising practical application of the MnS‐MoS2 electrode. This work is anticipated to afford an in‐depth comprehension of the heterostructure contribution in energy storage and illuminate a new perspective to construct binary transition metal sulfide anodes.

Synthesis and Supercapacitive Properties of Ni/Co-S Derived from MOF-74

Supercapacitors have been considered as one of the most promising energy storage devices for developing renewable energy resources with the increasing demands of energy and environmental protection. Binary transition metal sulfides have captured tremendous research interests in the field of supercapacitors due to their intrinsically high electrical conductivity and superior capacitive properties. In this work, the MOF-74 with Ni, Co and different ratios of Ni/Co (2:3, 1:1, 3:2) was synthesized by a facile solvothermal method, and then adopted as templates to derive Ni3S4, Co3S4 and NiCo sulfides by a heat treatment and subsequently solvothermal sulphidation. Electrochemical measurements show that the obtained rod-like sulfides have excellent capacitance properties. Notably, Co3S4 exhibits a high specific capacitance of 1843 F g-1 at 1 A g-1, which decreases to 930 F g-1 at 20 A g-1 with a retention of around 50%. While NiCo-S derived from NiCo-MOF-74 (Ni/Co=2:3) displays superior specific capacitances of 1910 F g-1 and 1160 F g-1 at 1 A g-1 and 20 A g-1, respectively, with a retention of above 60%. This clearly demonstrates that compared with Co3S4, NiCo-S has a higher specific capacitance and a better rate capability, which can be attributed to synergistic effects accompanying with the introduction of Ni.

Synthesis and Supercapacitive Properties of Ni/Co-S Derived from MOF-74

Supercapacitors have been considered as one of the most promising energy storage devices for developing renewable energy with increasing demands of energy and environmental protection. Binary transition metal sulfides have captured tremendous interests in the field of supercapacitors due to intrinsically high electrical conductivity and superior capacitive properties. In this work, MOF-74 with Ni, Co and different ratios of Ni/Co (2:3, 1:1, 3:2) are synthesized by a facile solvothermal method, and then adopted as templates to derive Ni3S4, Co3S4 and NiCo sulfides by a heat treatment and subsequently solvothermal sulphidation. Electrochemical measurements indicate that the obtained rod-like sulfides have excellent capacitance properties. Notably, Co3S4 exhibits a high specific capacitance of 1843 F g-1 at 1 A g-1, which decreases to 930 F g-1 at 20 A g-1 with a retention of circa 50%. While NiCo-S derived from NiCo-MOF-74 (Ni/Co=2:3) displays superior specific capacitance of 1910 F g-1 and 1160 F g-1 at 1 A g-1 and 20 A g-1, respectively, with a retention of above 60%. It shows that NiCo-S has higher specific capacitance and superior rate capability, which can be attributed to synergistic effects accompanying with the introduction of Ni.

Facile synthesis clusters of sheet-like Ni3S4/CuS nanohybrids with ultrahigh supercapacitor performance

Binary transition metal sulfides would have better electrochemical performance in supercapacitor, which can attribute to the synergistic effect, sufficient redox reaction and diversified nanostructure than single sulfides. In this work, new type clusters of sheet-like nickel sulfide and copper sulfide (Ni3S4/CuS) nanohybrids electrode was transformed from its hydroxide precursor through a facile chemical interface method, followed by an anion-exchange reaction. The Ni3S4/CuS composite electrode delivers much higher capacity of 970 ​C ​g-1 than its hydroxide precursor and those of the pristine Ni3S4 (559 ​C ​g-1) and CuS (148 ​C ​g-1), displays a good rate capability and cycling stability. When assembled an asymmetric capacitor, Ni3S4/CuS//AC (active carbon) presents high voltages up to 1.7 ​V and exhibits top energy density of 18.4 ​Wh Kg-1 even at high power density of 8500 ​W ​Kg-1. Such novel hybrids electrode and its synthesis method may provide a viable solution for energy storage materials issues.

Binary transition metal sulfides as an economical Pt-free counter electrodes for dye-sensitized solar cells

Binary CuxCoySz sulfide based Pt-free counter electrodes (CE) were prepared in one-step solvothermal synthesis process. The obtained CEs were characterized by SEM, XRD, and Raman spectroscopy methods. EDX analysis showed uniform distribution of Cu, Co and S. SEM images revealed different level of coverage of the FTO glass by the binary metal sulfide products. DSSCs were constructed using proposed CEs with N719 dye, and their photovoltaic and electrochemical performances were assessed against Pt reference cell. The efficiency of the CuxCoySz-3 CE produced an 11% improvement of its photovoltaic efficiency compared to the reference cell.

NiMoS4 nanocrystals anchored on N-doped carbon nanosheets as anode for high performance lithium ion batteries

Owing to the excellent electrical conductivity and high theoretical capacity, binary transition metal sulfides have attracted extensive attention as promising anodes for lithium ion batteries (LIBs). However, the relatively poor electrical conductivity and serious capacity fading originated from large volume change still hinder their practical applications. Herein, binary NiMoS4 nanoparticles are deposited on N doped carbon nanosheets (NC@NiMoS4) through a facile hydrothermal method. The N doped carbon nanosheets and the strong chemical bonding between NC and NiMoS4 can accommodate the volume change, keep the structural integrity and promote the ion/electron transfer during electrochemical reaction. The extra voids between NiMoS4 nanoparticles enlarge the contact area and reduce the lithium migration barriers. As anode for LIBs, the NC@NiMoS4 exhibits the excellent cycle stability with 834 mAh g−1 after 100 cycles at the current density of 100 mA g−1. Even at high rate of 2000 mA g−1, the specific capacity of 544 mAh g−1 can be achieved after 500 cycles.

Template-assisted synthesis of hierarchically hollow C/NiCo2S4 nanospheres electrode for high performance supercapacitors

Binary transition metal sulfides hold immense promise for use in energy storage devices thanks to their higher electronic conductivity and capacity compared to that of the mono-metal sulfides arising from the richer redox reactions. Herein, hierarchically hollow C/NiCo2S4 nanosphere composites have been synthesized through carbon coating and hydrothermal processes with SiO2 nanosphere and glucose as the hard template and carbon source, respectively. The interconnected NiCo2S4 nanosheets, void spaces in the interior of nanospheres and the conductive carbon layer enable the C/NiCo2S4 composite electrode to achieve an outstanding conductivity and good stability. Accordingly, the hollow C/NiCo2S4 nanosphere electrode exhibits an extraordinary specific capacitance of 1545 F g−1, as well as an enhanced cycling stability (90.1% after 6000 cycles) at a high current density of 10 A g−1. Satisfactory energy density (34.1 Wh kg−1 at 160 W kg−1) and high power density (8000 W kg−1 at 19.8 Wh kg−1) can be obtained by fabricating an asymmetric supercapacitor with activated carbon in the operation window of 0–1.6 V. These encouraging results further reveal the promising prospects of the as-prepared C/NiCo2S4 nanocomposite for high efficient electrochemical supercapacitor.

Rational synthesis of Cu7S4/CoS2 hybrid nanorods arrays grown on Cu foam from metal-organic framework templates for high-performance supercapacitors

Nanostructured copper sulfides with well-controlled morphologies, sizes, crystalline phases and compositions have been the subject of extensive research as the promising candidates in energy-related applications due to their excellent semiconducting properties and environmental compatibility. In this work, Cu7S4/CoS2 hybrid nanorods arrays on copper foam with different Co/Cu molar ratios (denoted as Cu-Co-S/CF-x, x = 0.12, 0.25 and 0.5) were firstly fabricated by a facile metal-organic framework templated synthetic strategy with three-step procedures of in situ interface growth, cation exchange and sulfurization. The optimized Cu-Co-S/CF-0.25 binder-free electrode displays the highest specific capacitance of 2132.7 mF cm−2 at a current density of 3 mA cm−2 (762.2 F g−1 at 1 A g−1) and outstanding cycling stability (92.3% capacitance retention over 10000 cycles). What's more, the assembled asymmetric supercapacitor (Cu-Co-S/CF-0.25//AC ASC) device based on Cu-Co-S/CF-0.25 as positive electrode and activated carbon (AC) as negative electrode offers a high energy density of 82.8 μWh cm−2 at the power density of 1.1 mW cm−2 (27.6 Wh kg−1 at 1125 W kg−1), which also demonstrates long-term cycling stability. These impressive results reveal that a rational and effective strategy has been explored to prepare binary transition metal sulfide nanorods arrays from metal-organic framework template for high-performance energy storage and conversion devices.

Hierarchical nanosheets-anchored-on-microsheets FeCo2S4 arrays as binder-free electrode for high-performance hybrid supercapacitor

The binary transition metal sulfides are highly desirable electrode materials for high-performance supercapacitors, thanks for their excellent electrochemical activity and electrical conductivity. Herein, the hierarchical FeCo2S4 arrays are designed and constructed on Ni foam, which consists of microsheets anchored nanosheets. The FeCo2S4 hierarchical structure provides high conductivity and abundant electroactive sites as well as facial and short ion transport paths. Therefore, the FeCo2S4 electrode achieves an excellent specific capacitance of 2488.50 F g−1 (7.66 F cm−2) at 5 mA cm−2, and a high level of cycle stability of 95.67% retention after 5000 cycles. The FeCo2S4//activated carbon (AC) device delivers the maximal energy density of 44.89 W h kg−1 and the maximal power density of 4015.56 W kg−1. The impressive electrochemical properties of hierarchical FeCo2S4 arrays make it a promising high-performance electrode for hybrid supercapacitors.

Hierarchical copper cobalt sulfides nanowire arrays for high-performance asymmetric supercapacitors

Binary transition metal sulfides are considered to be promising electrode materials for high-performance supercapacitors because of their ultrahigh electron conductivity and superior electrochemical activity compared to the unitary transition metal sulfides. In this work, copper cobalt sulfides nanowire arrays on nickel foam with different element ratios and porosities are prepared by using a two-step hydrothermal method, and their electrochemical performance is explored. Benefited from the high electrical conductivity, rich active sites and optimized microstructure, the optimized copper cobalt sulfides (CuCo2S4) electrode can achieve a ultrahigh specific capacitance of 2446.6 F·g−1 at 1 A·g−1 and favorable rate performance. The asymmetric supercapacitor assembled with the CuCo2S4 nanowire array and activated carbon (AC) electrodes displays a high energy density of 33.4 Wh·kg−1 at a power density of 751.5 W·kg−1 can be obtained. Additionally, the assembled asymmetric cell shows a favorable capacitance retention of 78% after charging and discharging for 10,000 cycles at a high current density of 4 A·g−1.

Facile Synthesis of Binary Transition Metal Sulfide Tubes Derived from NiCo‐MOF‐74 for High‐Performance Supercapacitors

Recently, binary transition metal oxides, phosphates, and sulfides have attracted wide attention due to their potential applications in supercapacitors. The emergence of metal‐organic frameworks (MOFs) provides new opportunities for the synthesis and investigation of porous binary metal compounds with similar microstructures. Herein, binary metal oxide (NiCo‐O) tubular structures are derived from NiCo‐MOF‐74 via a facile annealing process, and then phosphate (NiCo‐P) and sulfide (NiCo‐S) structures are obtained from NiCo‐O by heat treatment and solvothermal process, respectively. Among the three derivatives, NiCo‐S with nanosheet structures has the highest specific capacitance of 930.4 F g−1 at a current density of 1 A g−1 and an excellent rate capability with a retention of ≈80% at 10 A g−1. The long‐term cycling performance of NiCo‐S is superior with 70.5% retention after 10 000 cycles. The hybrid supercapacitor device with NiCo‐S and activated carbon as positive and negative electrodes delivers a high energy density of 22.6 W h kg−1 at a power density of 800 W kg−1. The excellent performance of NiCo‐S can be attributed to its nanosheet structure, which increases the specific surface area and electroactive sites.