MoS2 Phase Research Articles

Two-Dimensional Nonvolatile Valley Spin Valve.

A spin valve represents a well-established device concept in magnetic memory technologies, whose functionality is determined by electron transmission, controlled by the relative alignment of magnetic moments of the two ferromagnetic layers. Recently, the advent of valleytronics has conceptualized a valley spin valve (VSV)─a device that utilizes the valley degree of freedom and spin-valley locking to achieve a similar valve effect without relying on magnetism. In this study, we propose a nonvolatile VSV (n-VSV) based on a two-dimensional (2D) ferroelectric semiconductor where resistance of n-VSV is controlled by a ferroelectric domain wall between two uniformly polarized domains. Focusing on the 1T″ phase of MoS2, which is known to be ferroelectric down to a monolayer and using density functional theory combined with quantum transport calculations, we demonstrate that switching between the uniformly polarized state and the state with oppositely polarized domains separated by a domain wall results in a resistance change of as high as 107. This giant VSV effect occurs due to transmission being strongly dependent on matching (mismatching) the valley-dependent spin polarization in the two domains with the same (opposite) ferroelectric polarization orientations, when the chemical potential of 1T″-MoS2 lies within the spin-split valleys. The proposed n-VSV can be employed as a functional device for high-performance nonvolatile valleytronics.

Defect dependent electronic properties of two-dimensional transition metal dichalcogenides (2H, 1T, and 1T' phases).

Transition metal dichalcogenides (TMDs) exhibit a wide range of electronic properties due to their structural diversity. Understanding their defect-dependent properties might enable the design of efficient, bright, and long-lifetime quantum emitters. Here, we use density functional theory (DFT) calculations to investigate the 2H, 1T, and 1T' phases of MoS2, WS2, MoSe2, WSe2 and the effect of defect densities on the electronic band structures, focusing on the influence of chalcogen vacancies. The 2H phase, which is thermodynamically stable, is a direct band gap semiconductor, while the 1T phase, despite its higher formation energy, exhibits metallic behavior. 1T phases with spin-orbit coupling show significant band inversions of 0.61, 0.77, 0.24 and 0.78 eV for MoS2, MoSe2, WS2 and WSe2, respectively. We discovered that for all four MX2 systems, the energy difference between 2H, 1T and 1T phases decreases with increasing concentration of vacancies (from 3.13% to 21.88%). Our findings show that the 2H phase also has minimum energy values depending on vacancies. TMDs containing W were found to have a wider bandgap compared to those containing Mo. The band gap of 2H WS2 decreased from 1.81 eV (1.54 eV with SOC included) under GGA calculations to a range of 1.37 eV to 0.79 eV, while the band gap of 2H MoSe2 reduced from 1.43 eV (1.31 eV with SOC) under GGA to a range of 0.98 eV to 0.06 eV, depending on the concentration. Our findings provide guidelines for experimental screening of 2D TMD defects, paving the way for the development of next-generation spintronic, electronic, and optoelectronic devices.

Can structure influence hydrovoltaic energy generation? Insights from the metallic 1T' and semiconducting 2H phases of MoS2.

Hydrovoltaic power generation from liquid water and ambient moisture has attracted considerable research efforts. However, there is still limited consensus on the optimal material properties required to maximize the power output. Here, we used laminates of two different phases of layered MoS2 - metallic 1T' and semiconducting 2H - as representative systems to investigate the critical influence of specific characteristics, such as hydrophilicity, interlayer channels, and structure, on the hydrovoltaic performance. The metallic 1T' phase was synthesized via a chemical exfoliation process and assembled into laminates, which can then be converted to the semiconducting 2H phase by thermal annealing. Under liquid water conditions, the 1T' laminates (having a channel size of ∼6 Å) achieved a peak power density of 2.0 mW m-2, significantly outperforming the 2H phase (lacking defined channels) that produced a power of 2.4 μW m-2. Our theoretical analysis suggests that energy generation in these hydrophilic materials primarily arises from electro-kinetic and surface diffusion mechanisms. These findings highlight the crucial role of phase-engineered MoS2 and underscore the potential of 2D material laminates in advancing hydrovoltaic energy technologies.

Harnessing mixed-phase MoS2 for efficient room-temperature ammonia sensing.

Molybdenum disulfide (MoS2), a notable two-dimensional (2D) material, has attracted considerable interest for its potential applications in gas sensing, despite its typically insulating characteristics, which have limited its practical use. In this study, we present the use of mixed phase MoS2 (1T@2H-MoS2) to overcome sensing limitations of MoS2 material by enhancing its conductivity and demonstrating its high-performance characteristics for sensing ammonia (NH3) at room temperature (20 °C). The 1T@2H-MoS2 was synthesized via a hydrothermal process, and the coexistence of two different phases (the 1T and 2H phases) was confirmed by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The flower-like morphology was confirmed by field emission scanning electron microscopy (FESEM) and TEM. Our results indicate that the presence of both 1T and 2H phases within the material introduces sulfur vacancies, which we propose are critical to significantly enhancing its sensitivity to NH3 gas. The ammonia-sensing performance of the 1T@2H-MoS2 material was evaluated, and it demonstrated rapid and selective detection of NH3 gas across a wide concentration range (2 ppm to 100 ppm), with a very swift response time (7 s), fast recovery and high selectivity at room temperature without requiring heating. This improvement is attributed to the increased conductivity and effective active sites provided by the sulfur defects. This study underscores the potential of mixed-phase MoS2 in developing rapidly responsive and highly selective NH3 sensors, paving the way for the safety monitoring of hazardous gases in various industrial settings.

Metallic 1T Phase MoS2 Nanosheets Covalently Functionalized with BBD Molecules for Enhanced Supercapacitor Performances.

Metallic 1T phase molybdenum disulfide (MoS2) is among the most promising electrode materials for supercapacitors, but its capacitance and cyclability remain to be improved to meet the constantly increasing energy storage needs in portable electronics. In this study, we present a strategy, covalent functionalization, which achieves the improvement of capacitance of metallic 1T phase MoS2. Covalently functionalized by the modifier 4-bromobenzenediazonium tetrafluoroborate, the metallic MoS2 membrane exhibits increased interlayer spacing, slightly curled layered architecture, enhanced charge transfer, and improved adsorption capabilities toward electrolyte molecules and ions. Thanks to these boosted properties, the functionalized metallic MoS2 membrane exhibited excellent supercapacitor performances in a 0.5 M TBABF4 (acetonitrile as the solvent) electrolyte (with a specific capacitance of 135.67 F/cm3 at 1 A/g, more than three times that of the unfunctionalized metallic MoS2 membrane) and good stability, which can maintain a capacitance retention of 76.0% after 10 000 charge-discharge cycles.

Fully printed zero-static power MoS2 switch coded reconfigurable graphene metasurface for RF/microwave electromagnetic wave manipulation and control

Reduction of power consumption is the key target for modern electronic devices. To this end, a lot of attention is paid to zero-static power switches, being able to change their state between highly resistive and highly conductive and remain in this state even in the absence of external voltage. Still, the implementation of such switches is slow because of compatibility issues of new materials with CMOS technology. At the same time, printable technology enables low-cost processes at ambient temperature and integration of devices onto flexible substrates. Here we demonstrate that printed Ag/MoS2/Ag heterostructures can be used as zero-static power switches in radiofrequency/microwave spectrum and fully-integrated reconfigurable metasurfaces. Combined with graphene, our printed platform enables reconfigurable metasurface for electromagnetic wave manipulation and control for wireless communications, sensing, and holography. In addition, it is also demonstrated that the localised MoS2 phase change may have promoted Ag diffusion in forming conductive filaments.

A Coaxial Triboelectric Fiber Sensor for Human Motion Recognition and Rehabilitation via Machine Learning

This work presents the fabrication of a coaxial fiber triboelectric sensor (CFTES) designed for efficient energy harvesting and gesture detection in wearable electronics. The CFTES was fabricated using a facile one-step wet-spinning approach, with PVDF-HFP/CNTs/Carbon black as the conductive electrode and PVDF-HFP/MoS2 as the triboelectric layer. The incorporation of 1T phase MoS2 into the PVDF-HFP matrix significantly improves the sensor’s output owing to its electron capture capabilities. The sensor’s performance was carefully optimized by varying the weight percentage of MoS2, the thickness of the fiber core, and the CNT ratio. The optimized CFTES, with a core thickness of 156 µm and 0.6 wt% MoS2, achieved a stable output voltage of ~8.2 V at a frequency of 4 Hz and 10 N applied force, exhibiting remarkable robustness over 3600 s. Furthermore, the CFTES effectively detects human finger gestures, with machine learning algorithms further enhancing its accuracy. This innovative sensor offers a sustainable solution for energy transformation and has promising applications in smart portable power sources and wearable electronic devices.

Beneficial surface defect engineering of MoS2 electrocatalyst for efficient hydrogen evolution reaction

Hydrogen evolution reaction (HER) is considered the most efficient method for hydrogen production using an effective electrocatalyst. Molybdenum disulfide (MoS2), with its unique 2D layered structure, is the most promising electrocatalyst. This is attributed to its flexibility, which facilitates the exploration of various MoS2 phases and properties, closely mirroring those of platinum, particularly its Gibbs energy (ΔGH* ̃ 0.08 eV), which makes MoS2 an excellent electrocatalyst. However, its low electrical conductivity and inert basal planes limit its effectiveness for HER. This study utilized a facile hot-gun approach to successfully introduce sulfur vacancies, simultaneously incorporating oxygen from the air, which partially occupied these vacancies. This process resulted in the formation of an intermediate MoOxSy interlayer, yielding a highly effective electrocatalyst. Exposure to the hot gun for a short duration led to several changes, notably expanding the interlayer spacing and altering the atomic S:O ratio from approximately 75 % to 57 %, primarily affecting the MoS2 structure. The optimal duration for hot-gun treatment was determined to be 30 s, enhancing electrochemical activity for HER, with an overpotential of 486 mV vs. RHE (briefly marked as VRHE) at a current density of 10 mA·cm−2 and Tafel slope of 224 mV·dec-1. The improvement in basal active sites, attributable to the formation of defects from sulfur vacancies and partial passivation by oxygen at these sites, was identified as the key factor for this enhanced performance.

Synergistic effect of in-situ generated hydrogen peroxide on the degradation of sulfamethoxazole (SMX) by 1T-2H phase MoS2-activated PAA

Activation of peracetic acid (PAA) for pollutants degradation has been a hotspot recently. In this paper, sulfamethoxazole (SMX) is selected as the target pollutant, the degradation system consists of a TiO2 photoanode loaded with 1T-2H phase MoS2 and a nitrogen-doped ZnO cathode. The octahedral coordination and metallic properties of 1T-phase molybdenum disulfide endowed 1T-2H MoS2 with enhanced catalytic performance. Meanwhile, the cathode exhibited outstanding capabilities in generating H2O2 and facilitating its decomposition. In a weakly acidic environment, the SMX removal ratio of the 1T-2H MoS2/N-ZnO/PAA system within 30 min is 96.8 %, which is significantly higher than that of the 1T-2H MoS2/Pt/PAA system at 44.9 % and the 1T-2H MoS2/N-ZnO system at 33.1 %. After OH quenching, the degradation rate of PAA was found to significantly decrease, while the degradation rate of SMX remained almost unchanged. This suggests the hydroxyl radical (OH) preferentially reacts with PAA, leading to the formation of CH3C(O)OO rather than attacking SMX. This co-activation accelerates the formation of CH3C(O)OO and further promotes the degradation of SMX. Overall, this study systematically investigated the overlooked but crucial role of H2O2 in the decomposition of PAA process, which might provide valuable insights for better understanding the underlying mechanism in catalyzed PAA processes.

Se-Doped CoS2@MoS2 Heterostructures on Multiwalled Carbon Nanotubes as Efficient Bifunctional Electrocatalysts for Alkaline Overall Water Splitting.

The use of efficient and affordable non-precious metal catalysts for hydrogen and oxygen evolution reactions is vital for replacing and widely implementing new energy sources. Nevertheless, improving the catalytic performance of these non-precious-metal bifunctional electrocatalysts continues to be a major challenge. In this article, an optimized Se-incorporated bulk CoS2@MoS2 heterostructure grown on the surface of carbon nanotubes is reported. The resulting Se-CoS2@MoS2/CNTs exhibit robust bifunctional electrocatalytic performance, with low overpotentials of 85 and 240mV @ 10 mA·cm-2 for HER and OER, respectively. The materials exhibit superior long-term stability of over 145h, surpassing most electrocatalysts of similar type. This enhanced performance is attributed to the synergistic effect at the interface between the MoS2 and CoS2 phases, abundant active sites, and high active surface area, which collectively improves the electron-transfer efficiency during the reaction process. Furthermore, the incorporation of the amorphous state of Se into the heterostructure yields a change in the crystallinity of the heterostructure in the electronic structure, which optimizes the adsorption and activation energy barriers of the catalytic intermediate. This study thus presents a promising approach to regulating anion doping in bifunctional electrocatalysts.

Effect of MoS2 Morphology on the Photocatalytic Degradation of 4-Nitrophenol to Aminophenol

Nitroaromatic compounds are frequently detected as contaminants in industrial or agricultural wastewaters. Wastewater discharge contributes to nitrophenol pollution of the aquatic environment. Toxicity and carcinogenicity of 4-nitrophenol cause serious impact on water bodies. The present study is devoted to investigates the photocatalytic degradation of p-nitrophenol to aminophenol by MoS2 photocatalyst. MoS2 nanoparticles were synthesized via a hydrothermal process and further characterized by using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), High resolution transmission microscopy (HRTEM), UV-Visible spectroscopy, Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy (XPS). X-ray analysis revealed the presence of 2H phase of MoS2 and XPS analysis determined its various oxidation states. Fourier Transformation Infra-Red Spectroscopy (FTIR) and Thermogravimetric analyses (TGA) were used to study the functional group and thermal stability. UV-Visible spectroscopy was used to study the degradation of 4-nitrophenol and reaction kinetics. Investigation results showed a significant effect of nanosheets over nanoflower morphology for degradation efficiency of 4 nitrophenol to aminophenol under natural Sunlight.

Enhanced Hg(II) reduction activity over two-dimensional n-n heterojunction MoS2/Bi2WO6 nanocomposites under visible light illumination

The engineering of band structure acts as an effective avenue to promote photocatalytic redox reactions, which can be achieved by fabricating heterojunction photocatalysts. Herein, MoS2 NPs were anchored on the surface of the mesoporous Bi2WO6 network through a facile sol-gel process to form heterostructure MoS2/Bi2WO6 nanocomposites. HR-TEM and XRD results of the obtained MoS2/Bi2WO6 nanocomposite verified the formation of the hexagonal phase of MoS2 and the orthorhombic one for Bi2WO6. The MoS2/Bi2WO6 nanocomposites displayed enhancemed harvest for the visible light domain and photocatalytic ability in comparison with the pristine Bi2WO6. The photocatalytic ability of MoS2/Bi2WO6 nanocomposites was assessed by the Hg(II) reduction upon visible light irradiation. The optimal 12 % MoS2/Bi2WO6 photocatalyst displayed the superior reduction of Hg(II) about 99 % after 50 min, and the rate constant reached 0.1220 min−1 according to pseudo-first-order kinetic, where it was larger three folds than pristine Bi2WO6 (0.0418 min−1). The outstanding photocatalytic ability of n-n heterojunction MoS2/Bi2WO6 photocatalyst was attributed to the huge surface area, wide photoabsorption, and high separation efficiency of photocarriers. The reduction ability of MoS2/Bi2WO6 photocatalyst remained at 94 % after five times recycle, indicating its good reusability and high stability. The obtained heterojunction with the S-scheme mechanism could inhibit the recombination of the photocarriers, thus leading to superb photocatalytic ability. This work emerges an efficient route to design S-scheme heterojunction Bi2WO6-based photocatalytic methods for energy conversion and environmental purification.

Interlayer-expanded 1T-phase MoS2 as a cathode material for enhanced capacitive deionization

Molybdenum disulfide (MoS2) is a potential material for capacitive deionization (CDI) electrodes due to its large surface area and theoretical capacitance. However, its low electrical conductivity and limited spacing between layers hinder the improvement of the desalination performance. In our research, we combined phase modulation and interlayer engineering methodologies to create a CDI electrode material made of metallic phase MoS2 with expanded interlayer spacing. The high conductivity of the metallic phase facilitates rapid charge transport, while the expanded interlayer spacing (increased from 6.2 Å to 9.8 Å) promotes effective utilization of active sites and reduces the barriers for ion diffusion. The created electrode showcases a notable specific capacitance (131.1 F g−1 at 10 mV s−1) and an elevated capacitive contribution percentage (81 %). Additionally, it demonstrates a high desalination capacity of 47.1 mg g−1 and a fast desalination rate of 2.4 mg g−1 min−1 in a 200 mg L−1 NaCl solution. Furthermore, our density functional theory (DFT) calculations validate the essential role played by enlarged interlayer spacing in promoting Na+ insertion and accelerating its diffusion kinetics.

High-yield preparation of 1T-MoS2 with excellent piezo-catalytic activity via W6+ doping for antibiotics degradation and Cr(VI) reduction: Mechanistic insights from characterizations to DFT calculations

Molybdenum disulfide (MoS2) is a promising piezoelectric material. Herein, a simple method is reported for the high-yield production of metallic (1 T) phase MoS2 which exhibits excellent piezo-catalytic activity by in-situ doping of trace amounts of W6+. At 1 wt% W6+ doping, the 1 T phase of the obtained MoS2 reaches a concentration as high as 85.56 % and the piezoelectric coefficient and piezoelectric response current increase by 1.67 and 1.18 times, respectively, as compared to pristine MoS2. Consequently, W1.0-MoS2 can remove more than 99.8 % of tetracycline and 97.3 % of Cr(VI) in 10 min. Experimental characterization and theoretical calculations indicate that the enhanced piezoelectric catalytic activity is attributed to the strong synergistic effect between 1T-MoS2 and W6+ doping, which facilitates the rapid generation of hydroxyl radicals and superoxide radicals. This new strategy of doping 1 T/2H-MoS2 with W6+ can significantly enhance the piezoelectric catalytic performance, providing important insights for the removal of pollutants.

Multi-interface and rich-defects 1T phase MoS2 combine with FeS anchored on reduced graphene oxide for efficient alkaline hydrogen evolution

Exploring and fabricating noble-metal-free and cost-effective electrocatalysts to minimise the excessive potential required is of great significance for alkaline hydrogen evolution reaction (HER). Herein, we report FeS/1T-MP MoS2@rGO heterostructure with 1T and 2H mixed phase MoS2 (1T-MP MoS2) combining with FeS anchored on reduced graphene oxide (rGO) matrix, which is synthetized by utilizing Anderson polyoxometalate as Fe–Mo precursor by a facile hydrothermal method. The FeS/1T-MP MoS2@rGO heterostructure in the form of interconnected nanosheet arrays with multiple interfaces and rich-defects, which is in favor of the immersion of the electrolyte and exposing more active sites. Benefiting from the synergistic advantages of 1T-MoS2, FeS and rGO, FeS/1T-MP MoS2@rGO heterostructure delivers enhanced conductivity, enlarged electrochemical active surface area, and eventually promote the HER kinetics. As expected, FeS/1T-MP MoS2@rGO heterostructure emerges prominent HER activity with low overpotentials of 102 and 256 mV to achieve current density of 10 and 100 mA cm−2, outperforming vast majority of the advanced 1T MoS2-based alkaline HER electrocatalysts.

Ingenious regulation and activation of sites in the 2H-MoS2 basal planes by oxygen incorporation for enhanced photocatalytic hydrogen evolution of CdS

The 2H phase of MoS2 has the advantages of stable phase structure and tunable preparation approach, while the unfavorable H adsorption ability at the basal plane sites hinders the H2 evolution performance. Here, we developed an effective strategy for the regulation of the basal plane properties of MoS2 via oxygen doping. It is demonstrated that the Gibbs free energy of hydrogen adsorption (ΔGH*) at the sites in the basal plane can be effectively optimized. Using oxygen-doped MoS2 (OMoS) as a cocatalyst, the constructed OMoS/CdS heterojunction photocatalyst shows a stronger built-in electric field and improved photocatalytic H2 production activity. The optimized OMoS/CdS sample with only 0.3 wt% OMoS loading amount achieved an H2 evolution rate of 58.47 mmol g-1h−1 under AM 1.5 light irradiation, which is significantly superior to that of conventional MoS2 modified CdS and even higher than the 1 wt% Pt modified CdS. Our results not only highlighted the significant potential of OMoS as a photocatalyst for hydrogen production, but also proposed a superior to and effective conception for optimizing the H2 evolution activity at the basal plane sites of 2H-MoS2.

Effect of Heterojunction Dynamics on Electrochemical Properties of ZnS/MoS2 Type-II Nanocomposite for Photovoltaic Application

In the present work, ZnS/MoS2 nanocomposite has been synthesized by hydrothermal route. X-ray diffraction analysis revealed ZnS and MoS2 phases, showing the crystallite size of 19.5 and 9.25 nm from W-H and S-S plots, respectively. The lattice parameters of MoS2 and ZnS were found to be a = b = 3.79 Å, c = 12.4 Å and a = b = 3.2 Å, and c = 9.5 Å, respectively. The dislocation density, stacking fault and strain from W-H and S-S plots were found to be 4.1 × 10−4, 2.4 × 10−3, −1.2 × 10-3 and −2.4 × 10−2, respectively. The absorbance peaks of the nanocomposite were observed at 209, 246 and 320 nm revealing a band gap of 3.3 eV with refractive index of 2.32. Scanning electron microscopy and transmission electron microscopy imaging demonstrated ZnS nanoparticles over MoS2 sheets with an average particle size of 45.9 and 23.8 nm, respectively. In cyclic voltammetry analysis, pure ZnS and nanocomposite showed maximum oxidation current of 0.25 and 0.51 mA, respectively. Electrochemical impedance spectroscopy analysis revealed the presence of Warburg diffusion with a high exchange current density of 2.5 mA along with electrolyte’s and working electrode’s resistance to be 1000 Ω and 100 Ω, respectively. Charge transfer resistance, Warburg impedance, electrical double layer capacitance and film’s capacitance was found to be 10 Ω, 1000 Ω·s−1/2, 100 μF and 1 μF, respectively.

Computational analysis of 1T-MoS2: Probing the interplay of layer-dependent electronic structure, quantum capacitance, charge density and mechanical properties

To meet the high energy demand of society, a conversion to renewable energy sources has become essential and energy should be appropriately stored for future use. This has led to the development of energy-storing devices such as supercapacitors (SCs). To enhance capacitive behavior, the concept of quantum capacitance (CQ) is unveiled, which results from the confinement of electrons in their energy states. In this work, 1T phase of MoS2 is studied as it has received a lot of attention because of its wide applications in the energy storage devices and electronics. Here, the electronic structure, CQ and surface charge density (σ) of one, two and three-layered structures of 1T phase is studied using Density Functional Theory. No bandgap is obtained in the Density of States (DOS) and the bands plot of 1T structure indicates their metallic character and the DOS is continuous in all three layers. The CQ of three-layered structure dominates over the other two layers throughout the potential window. The larger CQ and σ values are obtained as 1718.06 μF cm−2 and -1299.50 μC cm−2 for three-layered structure at −0.27 V and −1 V respectively. For analyzing the mechanical strength, Young's modulus is evaluated for optimized structure by applying uni-axial strain. The value is obtained as 177.37 GPa, which is a measure of elastic deformation behavior. The results suggest that the capacitive performance of 1T MoS2 for SC applications is better and it can function as flexible cathode material for asymmetric SC applications.

Cobalt-doped molybdenum sulfide as an interlayer facilitates polysulfide conversion to obtain high-performance lithium−sulfur batteries

Lithium–sulfur (Li–S) batteries are considered to be a promising energy storage system due to their theoretical specific capacity. However, the “shuttle effect” of polysulfides (LiPSs) and the slow redox kinetics of LiPSs in the conversion reaction have hindered their large−scale application. In this study, the Co-MoS2 is prepared and coated on the polypropylene (PP) separator of Li–S batteries. The Co elements are successful addition and uniform distribution in the Co-MoS2. This coating is designed to provide chemical adsorption and catalysis for LiPSs. Consequently, Li–S batteries with a Co-MoS2 interlayer exhibit outstanding long-cycle and high-rate performance. After 500 cycles at 0.5C, the reversible capacity is found to be 561 mAh g−1, with only a low-capacity reduction of 0.097 % per cycle. Furthermore, 602 mAh g−1 is delivered even at 4C. The results of electrochemical measurements and first principles calculations demonstrate that the high performance of Li–S batteries is attributed to the chemical adsorption and electrocatalysis roles of the Co-MoS2 interlayer, which inhibit the “shuttle effect” and enable fast redox reaction kinetics. In addition, the introduction of cobalt doping results in the formation of the 1T phase of MoS2, which enhances the conductivity of the Co-MoS2. The presence of plentiful cobalt-doped MoS2 defects provides abundant catalytic sites for the electrochemical reaction of LiPSs.

Nitrogen plasma-induced phase engineering and titanium carbide/carbon nanotubes dual conductive skeletons endow molybdenum disulfide with significantly improved lithium storage performance

MoS2/Ti3C2 MXene composite has emerged as a promising anode material for lithium storage due to the synergistic combination of high specific capacity offered by MoS2 and conductive skeleton provided by Ti3C2 MXene. However, its two-dimensional/two-dimensional (2D/2D) structure is susceptible to collapse after long cycles, while the inherent low conductivity of MoS2 limits its rate performance. In this study, we developed a novel approach combining plasma-induced phase engineering with dual skeleton structure design to fabricate a unique P-MoS2/Ti3C2/CNTs anode material featuring highly conductive 1T phase MoS2 and a stable one-dimensional/two-dimensional (1D/2D) architecture. Within this architecture, growth of MoS2 nanosheets on the surface of Ti3C2 cross-linked by carbon nanotubes (CNTs) was achieved. The resulting Ti3C2/CNTs dual skeleton not only provides robust mechanical support to prevent structural collapse during long cycles but also offers increased specific surface area and additional Li+ storage space, thereby enhancing the lithium storage capacity of the composite. Subsequent N2 plasma treatment induced a phase transition in MoS2 from 2H to 1T configuration. Density functional theory (DFT) calculations confirmed that the induced 1T-MoS2 exhibits higher conductivity and lower Li+ diffusion barrier compared to 2H-MoS2. Benefiting from these synergistic effects, our P-MoS2/Ti3C2/CNTs anode demonstrated remarkable electrochemical performance including a high reversible specific capacity of 1120 mAh g−1 at 0.1 A g−1, excellent cycling stability with a specific capacity retention of 670 mAh g−1 after 600 cycles at 1 A/g, and superior rate performance with a specific capacity of 614 mAh g−1 at 2 A g−1. This combined modification strategy will serve as guidance for designing other energy storage materials.