Transition Metal Sulfides Research Articles

Cerium Doping-Induced Enrichment of Ni3S4 Phase for Boosting Oxygen Evolution Reaction.

The development of low-cost transition metal compounds with high-performance for efficient oxygen evolution reaction (OER) is of great significance in promoting the development of electrocatalysis. In this study, a Ce-doped Ni3S4 catalyst (Ce0.2-Ni3S4) was synthesized through a one-step solvothermal method, where the doped rare earth element Ce induced the transformation of NiS to Ni3S4. The Ce0.2-Ni3S4 catalyst exhibited excellent OER performance in 1 M KOH. At a current density of 10 mA cm-2, it showed a low overpotential of 230 mV and a low Tafel slope of 52.39 mV dec-1. Long-term OER tests at the same potential lasted for 24 h without significant loss of current density. This work introduces a novel method of Ce element doping for modifying transition metal sulfides, providing new insights into the effective utilization of rare earth elements in the field of electrochemistry. It creates more chances for the progress of highly efficient catalysts for efficient OER, contributing to the advancement of electrocatalysis.

Synergistic promotion effects of MoS2 integrated transition metal sulfides nanoparticles towards efficient tetracycline destruction: Performance, mechanism and toxicity assessment

Construction of effective multi-component composite materials via architecture modulation to destruct antibiotic pollutants through activating peroxymonosulfate (PMS) remains a challenge. In this study, we report a two-step hydrothermal process to construct MoS2 nanosheets integrated with transition metal sulfide (CoS2, Cu2S and MnS) nanoparticles for activating PMS towards degrading emerging tetracycline (TC) antibiotic. Among the samples, CoS2@MoS2 is verified as the best PMS activator for TC destructing with a removal rate of 95.3% in 30 min. The CoS2@MoS2/PMS system also performs well under various reaction conditions. The dominant reactive oxygen species responsible for TC degradation is identified as 1O2. Furthermore, CoS2@MoS2-catalyzed PMS efficiently degrades TC into eleven intermediates via three possible pathways. The toxicity of these intermediates is evaluated, both in terms of acute/chronic toxicity and phytotoxicity. The presence of Mo4+ sites on the catalyst surface facilitates the rapid transfer of electrons from MoS2 to Co3+, promotes the regeneration of Co2+, and facilitates the redox cycle of Co3+/Co2+. Therefore, the synergistic effects between CoS2 and MoS2 are responsible for the efficient degradation of TC over the CoS2@MoS2/PMS system. This study establishes an architecture engineering strategy for preparing dual transition metal sulfides, which synergistically promote PMS activation towards the degradation of organic pollutants.

High-performance heterometallic photocatalysts afforded by polyoxometalate synthons for efficient H2 production

MoS2-based materials have emerged as photoelectric semiconductors characterized by a narrow band gap, high capacity for absorbing visible light, and reduced H2 adsorption energy comparable to Pt. These attributes render them appealing for application in photocatalytic hydrogen production. Despite these advantages, the widespread adoption of MoS2-based materials remains hindered by challenges associated with limited exposure to active sites and suboptimal catalytic hydrogen production efficiency. To address these issues, we have designed and synthesized a new class of highly dispersed bimetallic/trimetallic sulfide materials. This was achieved by developing polyoxometalate synthons containing Ni-Mo elements, which were subsequently reacted with thiourea and CdS. The resulting Ni3S2-MoS2 and Ni3S2-MoS2-CdS materials achieve photocatalytic hydrogen production rates of 2770 and 2873 μmol g–1h−1, respectively. Notably, the rate of 2873 μmol g–1h−1 for Ni3S2-MoS2-CdS surpassed triple (3.23 times) the performance of CdS and nearly sextuple (5.77 times) that of single MoS2. These materials outperformed the majority of MoS2-based photocatalysts. Overall, this study introduces a straightforward methodology for synthesizing bimetallic/trimetallic sulfides with enhanced photocatalytic H2 evolution performance. Our findings underscore the potential of transition metal sulfide semiconductors in the realm of photocatalysis and pave the way for the development of more sustainable energy production systems.

Dry-processed technology for flexible and high-performance FeS2-based all-solid-state lithium batteries at low stack pressure

All-solid-state lithium batteries (ASSLBs) are considered promising energy storage systems due to their high energy density and inherent safety. However, scalable fabrication of ASSLBs based on transition metal sulfide cathodes through the conventional powder cold-pressing method with ultrahigh stacking pressure remains challenging. This article elucidates a dry process methodology for preparing flexible and high-performance FeS2-based ASSLBs under low stack pressure by utilizing polytetrafluoroethylene (PTFE) binder. In this design, fibrous PTFE interweaves Li6PS5Cl particles and FeS2 cathode components, forming flexible electrolyte and composite cathode membranes. Beneficial to the robust adhesion, the composite cathode and Li6PS5Cl membranes are tightly compacted under a low stacking pressure of 100 MPa which is a fifth of the conventional pressure. Moreover, the electrode/electrolyte interface can sustain adequate contact throughout electrochemical cycling. As expected, the FeS2-based ASSLBs exhibit outstanding rate performance and cyclic stability, contributing a reversible discharged capacity of 370.7 mAh g−1 at 0.3C after 200 cycles. More importantly, the meticulous dQ/dV analysis reveals that the three-dimensional PTFE binder effectively binds the discharge products with sluggish kinetics (Li2S and Fe) to the ion–electron conductive network in the composite cathode, thereby preventing the electrochemical inactivation of products and enhancing electrochemical performance. Furthermore, FeS2-based pouch-type cells are fabricated, demonstrating the potential of PTFE-based dry-process technology to scale up ASSLBs from laboratory-scale mold cells to factory-scale pouch cells. This feasible dry-processed technology provides valuable insights to advance the practical applications of ASSLBs.

Achieving High-Rate and Stable Sodium-Ion Storage by Constructing Okra-Like NiS2/FeS2@Multichannel Carbon Nanofibers.

Transition metal sulfides (TMSs) are considered as promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacities. However, the relatively low electrical conductivity, large volume variation, and easy aggregation/pulverization of active materials seriously hinder their practical application. Herein, okra-like NiS2/FeS2 particles encapsulated in multichannel N-doped carbon nanofibers (NiS2/FeS2@MCNFs) are fabricated by a coprecipitation, electrospinning, and carbonization/sulfurization strategy. The combined advantages arising from the hollow multichannel structure in carbon skeleton and heterogeneous NiS2/FeS2 particles with rich interfaces can provide facile ion/electron transfer paths, ensure boosted reaction kinetics, and help maintain the structural integrity, thereby resulting in a high reversible capacity (457 mA h g-1 at 1 A g-1), excellent rate performance (350 mA h g-1 at 5 A g-1), and outstanding long-term cycling stability (93.5% retention after 1100 cycles). This work provides a facile and efficient synthetic strategy to develop TMS-based heterostructured anode materials with high-rate and stable sodium storage properties.

Accelerated Sulfur Redox Kinetics on Transition Metal Sulfide Electrocatalysts by Modulating Electronic‐State of Active Sites

AbstractLithium‐sulfur (Li‐S) batteries are considered a competitive next‐generation electrochemical energy storage device, while the shuttle effect of soluble lithium polysulfides (LiPSs) resulting from the sluggish redox kinetics severely impedes their practical applications. Herein, a novel cation doping strategy is demonstrated for substantially accelerating the sulfur redox kinetics on the transition metal sulfide (TMS) electrocatalysts by partially substituting cobalt atoms with in situ dissolved Ni dopants (NixCo3‐xS4, 0<x≤1). Theoretical calculations revealed that the doping of Ni in the spinel Co3S4 phase enables the electronic‐state modulation of metal active sites by realizing the upshift of the d‐orbital center, thus leading to good chemical adsorption of intermediates and low redox conversion barriers between LiPSs and solid Li2S products. This is confirmed by in‐depth electrochemical dynamics and in situ Raman characterizations, in which the obtained Ni0.5Co2.5S4 with hierarchical nanosheet structure delivers the stronger chemical affinity of Li2S6 and higher precipitation/dissociation capacity of Li2S in comparison to monometallic cobalt sulfides. Benefiting from these outstanding attributes, the assembled Li‐S batteries by incorporating Ni0.5Co2.5S4 electrocatalysts into S@carbon nanotube cathode (S@Ni0.5Co2.5S4/CNT) exhibit a high specific capacity of 1189 mAh g−1 with excellent rate performance of 596 mAh g−1 at 5 C and long‐term cycling performance over 600 cycles with a capacity decay of 0.06% per cycle at 1 C. More importantly, an ultrahigh reversible areal capacity of 6.6 mAh cm−2 can be achieved for S@Ni0.5Co2.5S4/CNT cathode even with a high sulfur loading of 6.1 mg cm−2. This work demonstrates a new insight into designing TMS electrocatalysts toward rapid redox conversion kinetics in Li‐S batteries.

Fabrication of nickel-cobalt sulfide heterostructures with stable thermodynamic interfaces and enhanced electrochemical performance

Transition metal sulfides (TMS) with multicomponent heterostructure have been widely used as electrodes in electrochemical energy storage devices due to their abundant electroactive sites and fast charge transfer across the interfaces. Different kinds of heterostructures with specific TMS are fabricated by various routes to date, but it is still poorly understood how specific thermodynamic interfaces can be designed and easily coupled. Herein, the spinel and cobalt-pentlandite crystal phases of nickel–cobalt sulfides were chosen as models to demonstrate the formation of epitaxial heterointerface. The density functional theory calculations revealed the easy combination and high compatibility of these two crystal phases at the (111) plane. Along this guideline, a novel NiCo2S4/[Ni, Co]9S8 heterostructure was synthesized by a facile one-step hydrothermal strategy, with nanosheet-like shapes and well-defined heterointerfaces along the [111] crystal direction. The formation mechanism of the epitaxial heterointerface was proposed through the combination of solid and liquid phase reaction fields. As a proof-of-concept application, the obtained NiCo2S4/[Ni, Co]9S8 heterostructure as redox electrode for supercapacitor exhibits an enhanced specific capacitance of 1780F g−1 at 1 A/g and high capacitance retention of 70 % at 20 A/g. Moreover, the assembled aqueous hybrid supercapacitor of NiCo2S4/[Ni, Co]9S8//activated carbon delivers a high energy density of 62.8 Wh kg−1 at 0.4 kW kg−1 and excellent electrochemical stability after 3000 cycles. This work provides a new perspective on the epitaxial design of nickel–cobalt sulfide heterostructure with good lattice match as a promising electrode in energy storage devices.

Deciphering multistep transformation mechanism of cobalt-vanadium bimetallic sulfides anode in sodium storage

Transition metal sulfides as a high specific capacity sodium-ion batteries (SIBs) anode which have been suffering from successive phase transitions bringing about stress changes, poor electronic conductivity and ineffective ion transport kinetics. Combining self-sacrificial templates and ion-exchange transition reaction mechanisms, herein, cobalt, vanadium bimetallic sulfides hollow nano-cubic boxes with nitrogen-doped nanocarbon coating layer (CoV2S4@NC) are designed to solve these symbiosis problems. With a combination of in-situ Raman, ex-situ XPS/TEM, and density-functional theory calculations, the synergistically coordination mechanism between cobalt and vanadium binary metal during multi-step conversion processes is responsible for the faster charge transfer kinetics and boosted Na+ pseudocapacitance storage capability. Furthermore, the hollow cubic structure combined with the carbon shell layer can release the internal stress during phase transitions and avoid the recurrent growth of SEI film by volume change during the electrochemical process, thus realizing a superior electrode/electrolyte interface. Thus, when used as anode materials for SIBs, the prepared anode materials display excellent electrochemical performance, delivering capacity of 492 mA h g−1 at a current density of 10 A g−1 and high capacity stability with 484 mAh g−1 after 1000 cycles at 5 A g−1. More importantly, the assembled full cell (Na3V2(PO4)3//CoV2S4@NC) also shows high capacity of 574 mAh g−1 with 94.7% capacity retention after 85 cycles, suggesting the potential application of bimetallic sulfides in SIBs.

Simple and affordable synthesis of a binder-free nickel-zinc sulfide electrode for high-performance supercapacitors

Due to the increasing demand for renewable energy solutions, aqueous energy systems have emerged as promising and sustainable technologies. Nanostructured transition metal sulfides, renowned for their exceptional properties, are prime candidates for electrochemical supercapacitors. In this study, we present the synthesis of nickel-zinc sulfide (Ni-Zn-S) as a binder-free supercapacitor material using the affordable successive ionic layer adsorption and reaction simple technique. The active nanomaterial was directly deposited onto a 3D Ni foam current collector substrate, negating the need for a binder. The synergistic combination of Ni and Zn enhances the electrode capacitance. Various electrochemical techniques were used to evaluate the loaded active material as a binder-free supercapacitor electrode in a 6 M KOH electrolyte. Results indicate pseudocapacitive performance, achieving a high specific capacitance of 400F/g at 0.7 A/g. This material retains 97 % of its capacity, even after 2000 cycles, showcasing exceptional long-term cycling stability. These findings underscore the potential of the Ni-Zn-S electrode for delivering low-cost, high-performance supercapacitors.

Composite of CoS1.97 nanoparticles decorated CuS hollow cubes with rGO as thin film electrode for high-performance all solid flexible supercapacitors

Stretchable flexible thin-film electrodes are extensively explored for developing new wearable energy storage devices. However, traditional carbon-based materials used in such independent electrodes have limited practical applications owing to their low energy storage capacity and energy density. To address this, a unique structure and remarkable mechanical stability thin-film flexible positive electrode comprising CoS1.97 nanoparticles decorated hollow CuS cubes and reduced graphene oxide (rGO), hereinafter referred to as CCSrGO, is prepared. Transition metal sulfide CoS1.97 and CuS shows high energy density owing to the synergistic effects of its active components. The electrode can simultaneously meet the high-energy density and safety requirements of new wearable energy storage devices. The electrode has excellent electrochemical performance (1380 F/g at 1 A/g) and ideal capacitance retention (93.8 % after 10,000 cycles) owing to its unique three-dimensional hollow structure and polymetallic synergies between copper and cobalt elements, which are attributed to their different energy storage mechanisms. Furthermore, a flexible asymmetric supercapacitor (FASC) was constructed using CCSrGO as the positive electrode and rGO as the negative electrode (CCSrGO//rGO), which delivers an energy density of 100 Wh kg−1 and a corresponding power density of 2663 W kg−1 within a voltage window of 0–1.5 V. The resulting FASC can power a light-emitting diode (LED) at different bending and twisting angles, exerting little effect on the capacitance. Therefore, the prepared CCSrGO//rGO FASC devices show great application prospects in energy storage.

Understanding the unique Ohmic-junction for enhancing the photocatalytic activity of CoS2/MgIn2S4 towards hydrogen production

MgIn2S4 is a photocatalyst with a suitable band gap for renewable energy production, but its effectiveness is hindered by pronounced photocorrosion, insufficient surface active sites and rapid charge recombination. Herein, we report the synthesis of CoS2/MgIn2S4 Ohmic junction with a robust internal electric field. The optimized CoS2/MgIn2S4 photocatalyst with a CoS2 loading of 20.5 wt%, depicts a maximum H2 evolution rate of 290 μmol g−1 h−1, which is 3.1 times higher than the value of MgIn2S4. The improved photocatalytic activity of CoS2/MgIn2S4 can be attributed to the intimate Ohmic junction at the CoS2/MgIn2S4 interface, which promotes effective photoelectron transfer from MgIn2S4 to CoS2. Simultaneously, CoS2 can act as an efficient surface cocatalyst, with an optimal hydrogen-adsorption Gibbs free energy, enabling highly efficient proton reduction at the catalyst/H2O interface. The present work introduces a novel approach to modulate interfaces, creating transition metal sulfide cocatalysts for photocatalysts, resulting in high photocatalytic performance.

Boosting hydrogen production from alkaline water splitting by regulating interlayer stress via lattice mismatch in NiS/MoS2

Alkaline water splitting currently represents one of the most promising routes for sustainable hydrogen production. However, the key challenge with this method lies in the development of low-cost catalysts showing high-performance for hydrogen evolution reaction (HER). Given the rapid advances in the structural design of HER catalysts, a potential procedure to boost their performance is introduced herein. A controllable interlayer stress is generated at the homojunction NiS/NiS interface of electrodeposited hybrid transition metal sulphide NiS/MoS2, by precisely regulating lattice mismatches of NiS nanostructures, achieve a precise control over its charge transfer resistance and the effective balance of electrochemical area. Accordingly, an optimal design, NM5030 (NiS(50 mA/cm2)-NiS(20 mA/cm2)/MoS2/CC), showing an excellent HER performance in alkaline electrolyte is produced. It can drive a high current density of 10 mA/cm2, 100 mA/cm2 and 400 mA/cm2 at a low overpotential of 18 mV, 93 mV and 161 mV, respectively. Under chronoamperometric test, no obvious reduction in current density is observed after 48 h, indicating its high stability. Overall, this work demonstrates the feasibility and effectiveness of the strategy of fabricating lattice mismatch to find an optimal layered structure based catalyst for efficient HER.

Constructing mixed-dimensional lightweight magnetic cobalt-based composites heterostructures: An effective strategy to achieve boosted microwave absorption and self-anticorrosion

Subtle microstructure design and an appropriate multicomponent strategy are essential for advanced electromagnetic absorbing (EMA) materials with a wide effective absorption bandwidth (EAB) and intense absorption. However, sophisticated environments restrict the range of applications for EMA materials. Herein, three hollow spherical bifunctional CoSx/MnS/C nanocomposites with different crystal structures were constructed via cation exchange and subsequent vulcanization. The manganese sulfide and carbon generated during vulcanization exhibit a narrow band gap and enhanced conductivity, thereby facilitating conductive loss. The presence of cobalt sulfide facilitates the improvement of magnetic loss. More importantly, there is a potential difference between different phases at the heterogeneous interface, resulting in a region of space charge, which is conducive to interfacial polarization. The 3D hollow structure and heterogeneous dielectric/magnetic interfaces benefit the predominant EMA performance by forming perfect impedance matching, interface polarization, conduction loss, and magnetic loss effects. Specifically, an optimal reflection loss (RL) of –51.31 dB at 10.72 GHz and an effective EAB of 5.92 GHz at 2.1 mm can be achieved for Co1–xS/MnS/C nanocomposite. Moreover, the nanocomposites maintained promising self-anticorrosion properties in simulated seawater environments. Transition metal sulfides with superior self-anticorrosion properties provide a pathway to efficient wave-absorbing materials in complicated environments.

Resource recovery and regeneration strategies for spent lithium-ion batteries: Toward sustainable high-value cathode materials

Traditional cathode recycling methods have become outdated amid growing concerns for high-value output and environmental friendliness in spent Li-ion battery (LIB) recycling. Our study presents a closed-loop approach that involves selective sulfurization roasting, water leaching, and regeneration, efficiently transforming spent ternary Li batteries (i.e., NCM) into high-performance cathode materials. By combining experimental investigations with density functional theory (DFT) calculations, we elucidate the mechanisms within the NCM-C-S roasting system, providing a theoretical foundation for selective sulfidation. Utilizing in situ X-ray diffraction techniques and a series of consecutive experiments, the study meticulously tracks the evolution of regenerating cathode materials that use transition metal sulfides as their primary raw materials. The Li-rich regenerated NCM exhibits exceptional electrochemical performance, including long-term cycling, high-rate capabilities, reversibility, and stability. The closed-loop approach highlights the sustainability and environmental friendliness of this recycling process, with potential applications in other cathode materials, such as LiCoO2 and LiMn2O4. Compared with traditional methods, this short process approach avoids the complexity of leaching, solvent extraction, and reverse extraction, significantly increasing metal utilization and Li recovery rates while reducing pollution and resource waste.

3D-structured Co9S8@NSG prepared using deep eutectic solvents as high-performance anode material of lithium-ion batteries

Transition metal sulfides (TMSs) are ideal materials for replacing graphite anodes in lithium-ion batteries (LIBs). However, their low conductivities and large volume changes during charge/discharge cycling greatly limit their applications. Herein, a new method for co-doping nitrogen and sulfur in 3D graphene via a one-step method in deep eutectic solvents (DESs) was developed to prepare Co9S8@NSG composites, enhancing the storage performance of LIBs. The obtained Co9S8@NSG nanosheets exhibited excellent lithium-ion storage performance as anode materials. In the first cycle, the electrode material possessed high specific capacity (1647.5 mAh·g−1 at a current density of 2 a·g−1). After 250 cycles, the reversible capacity was still maintained at 516 mAh·g−1. The electrode material also displayed good cycling stability with specific capacity reaching 710 mAh·g−1 after 700 cycles at a current density of 0.5 a·g−1. In sum, the developed route for the synthesis of heteroatom-doped nanocomposites looks promising for modification of sulfide materials as excellent-performance LIBs.

Design and synthesis of active site rich cobalt tin sulfide nano cubes: An effective electrochemical sensing interface to monitor environmentally hazardous phenolic isomers

In the present study, we synthesized Cobalt Tin Sulfide Nano Cubes (CoSnS2) using a simple sol–gel method, and the structural and morphological characterizations were performed to confirm the effectiveness and feasibility of the approach without any impurities. Further, to serve as an electrochemical interface for sensing dihydroxy benzene isomers (DHBIs), CoSnS2 nanoparticles were drop cast on the surface of the glassy carbon electrode (GCE). From the electrochemical characterizations, CoSnS2/GCE shows improved electrochemical performance than bare GCE, and can selectively detect DHBIs. The limits of detection (LODs) calculated for individual determination of catechol (CC) and hydroquinone (HQ) at CoSnS2/GCE was 10.21 nM (5.0–135.0 µM) and 12.56 nM (5.0–135.0 µM), respectively. Also, possible interference does notgreatly affect the analytical performance ofthe modified electrode.Overall, we investigated the simple synthesis of transitional-metal sulfides (TMSs) and their electrochemical sensing applications to chemicals that are dangerous to the environment. We anticipate that the easy approach proposed herein will be very attractive for producing and commercializingelectrochemical sensing devices in the future.

Rod-like Ni-CoS2@NC@C: Structural design, heteroatom doping and carbon confinement engineering to synergistically boost sodium storage performance

Currently, conversion-type transition metal sulfides have been extensively favored as the anodes for sodium-ion batteries due to their excellent redox reversibility and high theoretical capacity; however, they generally suffer from large volume expansion and structural instability during repeatedly Na+ de/intercalation. Herein, spatially dual-confined Ni-doped CoS2@NC@C microrods (Ni-CoS2@NC@C) are developed via structural design, heteroatom doping and carbon confinement to boost sodium storage performance of the material. The morphology of one-dimensional-structured microrods effectively enlarges the electrode/electrolyte contact area, while the confinement of dual-carbon layers greatly alleviates the volume change-induced stress, pulverization, agglomeration of the material during charging and discharging. Moreover, the introduction of Ni improves the electrical conductivity of the material by modulating the electronic structure and enlarges the interlayer distance to accelerate Na+ diffusion. Accordingly, the as-prepared Ni-CoS2@NC@C exhibits superb electrochemical properties, delivering the satisfactory cycling performance of 526.6 mA h g−1 after 250 cycles at 1 A g−1, excellent rate performance of 410.9 mA h g−1 at 5 A g−1 and superior long cycling life of 502.5 mA h g−1 after 1,500 cycles at 5 A g−1. This study provides an innovative idea to improve sodium storage performance of conversion-type transition metal sulfides through the comprehensive strategy of structural design, heteroatom doping and carbon confinement.

Carbon fibers coated with floral MoSe2 are applied to high-performance electromagnetic absorbing materials

Studied the microwave absorption performance of carbon fiber, mixed carbon fiber/MoSe2 (CM) bilayer composite materials in the range of 2–18 GHz. The flower-shaped layer and core-shell double-layer interface of MoSe2 work together to improve electromagnetic wave absorption, providing a new approach for designing lightweight, broadband, and strong absorption-absorbing materials. To address the drawbacks of the high conductivity of pure carbon fibers, transition metal sulfides were introduced promptly, and the CM core-shell materials with flower-shaped outer shell structures were prepared. An in-depth analysis of the working mechanism of CM absorbing materials and the influence of the interface between carbon fibers and MoSe2 on the absorbing performance has been conducted, providing a favorable experimental basis for the application of fiber membranes in absorbing materials.

Short-term cathodic tuning atomic-level S-S interaction of CuS for heavy metal ultrafast detoxication

Transition metal sulfides have demonstrated excellent heavy metal detoxification in previous studies. However, the activity of their S-functional sites is usually not maximized because they are not precisely regulated. Herein, we report a new short-term cathodic tuned CuS crystals (C-tuned CuS) distortion strategy, ultrafast detoxicating over 95% Cr(VI) in 1 min，its detoxification rate was elevated by five orders of magnitude times compared to the untuned one. The high Cr(VI) detoxification performance is mainly attributed to the layered sulfur atoms tuning within series of cathodic potential shown by In-situ Raman. Besides, the four-tuning stages of C-tuned CuS lattice distortion based on the variation of Raman peak height and redshift changes was investigated by density functional theory (DFT) calculations, showing that the S-S bonds was stretched under cathodic tuning, extending from 2.106 to 2.345 Å. The stretched S-S bonds with enhanced polarity and electron activity prevailed the formation of transient Cr-S bonds with Cr(VI), favoring the direct electron transfer without O mediation, thus reducing the Cr(VI) reduction energy barrier. Cathodic tuning CuS crystal distortion, a “Plug and Play” strategy, show a new electron-level microscopic insights into wastewater reduction techniques development.

A Defective Disc-Like Cu1.96S Anode Material with the Efficient Cu Vacancies for High-Performance Sodium-Ion Storage.

Due to their significant capacity and reliable reversibility, transition metal sulphides (TMSs) have received attention as potential anode materials for sodium-ion batteries (SIBs). Nonetheless, a prevalent challenge with TMSs lies in their significant volume expansion and sluggish kinetics, impeding their capacity for rapid and enduring Na+ storage. Herein, a Cu1.96S@NC nanodisc material enriched with copper vacancies is synthesised via a hydrothermal and annealing procedure. Density functional theory (DFT) calculations reveal that the incorporation of copper vacancies significantly boosts electrical conductivity by reducing the energy barrier for ion diffusion, thereby promoting efficient electron/ion transport. Moreover, the presence of copper vacancies creates ample active sites for the integration of sodium ions, streamlines charge transfer, boosts electronic conductivity, and, ultimately, significantly enhances the overall performance of SIBs. This novel anode material, Cu1.96S@NC, demonstrates a reversible capacity of 339mAhg-1 after 2000 cycles at a rate of 5Ag-1. In addition, it maintains a noteworthy reversible capacity of 314mAhg-1 with an exceptional capacity retention of 96% even after 2000 cycles at 20Ag-1. The results demonstrate that creating cationic vacancies is a highly effective strategy for engineering anode materials with high capacity and rapid reactivity.