1T Phase MoS2 Research Articles

Space-Confinement and in Situ Reduction of Pt with 1T-MoS2 for Exceptional Hydrogen Evolution Reaction in Simulated Seawater.

Efficient catalysts for hydrogen generation from seawater are essential for advancing clean energy technologies. In this study, we present a straightforward method for producing Pt nanoparticles enclosed within metallic 1T-phase MoS2 nanosheets on graphite paper as a promising catalyst for the hydrogen evolution reaction (HER). The resulting 14.3 wt % Pt-MoS2 nanosheets demonstrate an ultralow onset potential of 65.6 mV vs the reversible hydrogen electrode (RHE) and a minimal Tafel slope of 64 mV/dec with remarkable stability and durability in simulated seawater, offering comparable catalytic performance to the 40 wt % Pt/C commercial catalyst at a lower cost. This exceptional hydrogen production is attributed to the robust reducing ability of 1T-phase MoS2 and the confinement of Pt nanoparticles within the MoS2 interlayers and nanosheets. Our findings highlight the significance of this approach in developing practical and sustainable electrocatalysts for seawater splitting. This research represents a crucial step toward a greener and more sustainable future, leveraging innovative catalyst design strategies for clean energy production.

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.

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.

Bottom-up Synthesis of Highly Chiral 1T Molybdenum Disulfide Nanosheets.

Chirality in inorganic nanostructures has recently stimulated the attention of many researchers, both to unravel fundamental questions on the origin of chirality in inorganic and hybrid materials, as well as to introduce novel promising properties that are originated by the symmetry breaking. MoS2 is one of the most investigated among the large family of layered transition metal dichalcogenides. In particular, the metastable metallic 1T-MoS2 phase is of large interest for potential applications. However, due to thermodynamic reasons, the synthesis of 1T-MoS2 phase is quite challenging. Herein, we present the first synthesis of chiral 1T-MoS2 phase which shows remarkably high chiroptical activity with a g-factor up to 0.01. Chiral 1T-MoS2 was produced using tartaric acid as a chiral ligand to induce symmetry breaking during the material's growth under hydrothermal conditions, leading to the formation of distorted hierarchical nanosheet assemblies exhibiting chiral morphology. Thorough optimization of the synthetic conditions was carried out to maximize chiroptical activity, which is strongly related to the nanostructures' morphology. Finally, the formation mechanism of the chiral 1T-MoS2 nanosheet assemblies was investigated, focusing on the role of molecular intermediates in the growth of the nanosheets and the transfer of chirality.

Growth and stabilization of high-concentration metallic 1T-phase MoS2 as a high-performance l-cysteine electrochemical sensor by electron injection engineering

MoS2 is an attractive electrochemical sensing electrode material for the detection of biomolecule because of its adjustable band gap, large surface area, and unique electrochemical characteristics. However, the poor catalytic and electrical conductivity of the semiconductor 2H-phase MoS2 and the phenomenon of restacking during electrochemical use hinder its sensing application. Herein, electron injection engineering is employed for the formation and stabilization of high-concentration metal 1T-phase MoS2 nanosheets on ionic liquid-functionalized carbon nanotubes (CNTs-IL). The increase of MoS2 concentration in the metal 1T phase significantly accelerates electron transfer kinetics. The in-situ growth method results in a tightly interfaced coupling effect, thereby substantially shortening the electron transport pathway and decreasing interfacial transmission impedance. In addition, the sulfur defects on the surface of MoS2 as the anchoring point of sulfhydryl groups promote the enrichment of thiols on the surface of the material and reduce the reaction barrier for sulfhydryl oxidation, thereby improving the catalytic performance. The prepared CNTs-IL-MoS2/SPE biosensor shows excellent l-cysteine sensing performance by electrochemical detection.

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.

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.

Fe doping 1T phase MoS2 with enhanced zinc-ion storage ability and durability for high-performance aqueous zinc-ion batteries

Fe doping 1T phase MoS2 with enhanced zinc-ion storage ability and durability for high-performance aqueous zinc-ion batteries

Quasi-Solid-State Electrolyte Induced by Metallic MoS2 for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are a promising high-energy-density technology for next-generation energy storage but suffer from an inadequate lifespan. The poor cycle life of Li-S batteries stems from their commonly adopted catholyte-mediated operating mechanism, where the shuttling of dissolved polysulfides results in active material loss on the sulfur cathode and surface corrosion on the lithium anode. Here, we report in situ formation of a quasi-solid-state electrolyte (QSSE) on the metallic 1T phase molybdenum disulfide (MoS2) host that extends the lifetime of Li-S batteries. We find that the metallic 1T phase MoS2 host is able to initiate the ring-opening polymerization of 1,3-dioxolane (DOL), forming an integrated QSSE inside batteries. Nuclear magnetic resonance analysis reveals that the QSSE consists of ∼13% liquid DOL in a solid polymer matrix. The QSSE efficiently mediates sulfur redox reactions through dissolution-conversion chemistry while simultaneously suppressing polysulfide shuttling. Therefore, while ensuring high sulfur utilization, it avoids degradation of both electrodes, as well as the concomitant electrolyte consumption, leading to enhanced cycling stability. Under a practical lean electrolyte condition (electrolyte-to-sulfur ratio = 2 μL mg-1), Li-S pouch cell batteries with the QSSE demonstrate a capacity retention of 80.7% after 200 cycles, much superior to conventional liquid electrolyte cells that fail within 70 cycles. The QSSE also enables Li-S pouch cell batteries to operate across a wider temperature range (5 to 45 °C), together with improved safety under mechanical damage.

Stabilizing and Activating Active Sites: 1T-MoS2 Supported Pd Single Atoms for Efficient Hydrogen Evolution Reaction.

Metallic 1T-MoS2 with high intrinsic electronic conductivity performs Pt-like catalytic activity for hydrogen evolution reaction (HER). However, obtaining pure 1T-MoS2 is challenging due to its high formation energy and metastable properties. Herein, an in situ SO4 2--anchoring strategy is reported to synthesize a thin layer of 1T-MoS2 loaded on commercial carbon. Single Pd atoms, constituting a substantial loading of 7.2wt%, are then immobilized on the 1T-phase MoS2 via Pd─S bonds to modulate the electronic structure and ensure a stable active phase. The resulting Pd1/1T-MoS2/C catalyst exhibits superior HER performance, featuring a low overpotential of 53mV at the current density of 10mAcm-2, a small Tafel slope of 37mVdec-1, and minimal charge transfer resistance in alkaline electrolyte. Moreover, the catalyst also demonstrates efficacy in acid and neutral electrolytes. Atomic structural characterization and theoretical calculations reveal that the high activity of Pd1/1T-MoS2/C is attributed to the near-zero hydrogen adsorption energy of the activated sulfur sites on the two adjacent shells of atomic Pd.

Three-dimensional Co–MoS2/Ni3S2/Ni assembly with interfacial engineering and electronic modulation for efficient hydrogen evolution reaction

To maximize the active sites and accelerate the electron transfer are of significant importance for developing efficient MoS2-based catalysts towards hydrogen evolution reaction (HER). Herein, we report a facile one-step construction of three-dimensional assembly in which Co doped MoS2 nanoflowers are attached on partially sulfided nickel foam (Co–MoS2/Ni3S2/Ni). The three-dimensional structure enables maximum exposure of the active sites. Besides, interfacial interaction between MoS2 and Ni3S2 accelerates the electron transfer kinetics and increases the electrochemically active surface area. Additionally, electronic synergy effect of Co to MoS2 promotes the formation of 1T-MoS2 phase. Consequently, the optimized Co–MoS2/Ni3S2/Ni catalyst shows a superior HER performance with low overpotentials of 43 mV and 201 mV to achieve the current densities of 10 mA/cm2 and 100 mA/cm2, as well as an excellent stability of 11 h. Besides, Co–MoS2/Ni3S2/Ni has a small Tafel slope of 53 mV dec−1 which indicates a combined Volmer-Heyrovsky mechanism during the HER process. This work provides a novel insight for designing excellent MoS2-based HER catalysts through electronic modulation and interfacial engineering.

Structural and optical properties of 1T-MoS2/MoO3 thin films prepared by spray pyrolysis method

Electrical properties of the devices based on two dimensional (2D) transition metal dichalcogenids thin films, is highly depended to their producing method and preparation conditions. In the present work structural and optical properties of MoS2/MoO3 nano-heterostructure films prepared by spray pyrolysis technique were studied. X-ray diffraction analysis revealed a phase transformation from hexagonal semiconducting 2H–MoS2 to octahedral metallic 1T-MoS2 phase by decreasing the molarity of ammonium molybdate as the precursor solution. The controllable phase transition provides a degree of freedom to pave the way for more novel devices. UV–Vis absorption spectra and photoluminescence (PL) spectroscopy confirm the presence of monolayer MoS2 with a direct band gap of ∼1.84 eV, related to a peak position at 674 nm in the composite. A change in the sample's band gap by annealing treatment on the hybrid films is, here reported. We found three different band gap of 1.7, 2.1 and 2.25 eV for the three composite samples and discussed the case. The highest PL quantum yield (QY) of the 1T-MoS2 based composite make it as a better candidate for photocatalysis applications. A brief discussion of the Raman spectra analysis from a prepared MoS2/MoO3 sample is also included. The present work illustrates the potential use of composite based heterostructures in electrical devises where higher conductivity of the metallic phase of MoS2 nanostructures is needed.

Confinement and phase engineering boosting 1T phase MoS2/carbon hybrid for high‐performance capacitive deionization

AbstractCapacitive deionization (CDI) has attracted significant attention as a water treatment technology owing to its low cost, high efficiency, and eco‐friendliness. However, the unsatisfactory desalination performance of traditional electrode materials hinders the development of CDI. Herein, 1T‐MoS2/C hybrid microspheres are successfully fabricated through confinement and phase engineering strategies. The confinement effect of porous hollow carbon microspheres reduces the overgrowth and agglomeration of MoS2 nanosheets, which is beneficial for exposing more active sites and enhancing stability. Meanwhile, the 1T phase MoS2 displays high intrinsic conductivity and large interlayer spacing, which is conducive to rapid insertion/extraction of Na+. Consequently, 1T‐MoS2/C hybrid becomes a prospect electrode material for CDI, which showcases outstanding desalination capacity (48.1 mg/g at 1.2 V), eminent desalination rate as well as exceptional stability. Moreover, the desalination mechanisms are clarified through various characterizations and density functional theory calculations. This study provides new perspectives on designing high‐performance MoS2‐based CDI electrode materials.

Dual-vacancies modulation of 1T/2H heterostructured MoS2-CdS nanoflowers via radiolytic radical chemistry for efficient photocatalytic H2 evolution

Precise defect engineering of photocatalysts is highly demanding but remains a challenge. Here, we developed a facile and controllable γ-ray radiation strategy to assemble dual-vacancies confined MoS2-CdS-γ nanocomposite photocatalyst. We showed the solvated electron induced homogeneous growth of defects-rich CdS nanoparticles, while the symbiotic •OH radicals etched flower-like 1T/2H MoS2 substrate surfaces. The optimal MoS2-CdS-γ exhibited a H2 evolution rate of up to 37.80 mmol/h/g under visible light irradiation, which was 36.7 times higher than that of bare CdS-γ, and far superior to those synthesized by hydrothermal method. The microscopic characterizations and theoretical calculations revealed the formation of such unprecedented dual-sulfur-vacancies ensured the tight interfacial contact for fast charge separation. Besides, the existence of 1T-MoS2 phase further improved the conductivity and strengthened the adsorption interaction with H+ intermediate. Therefore, the radiolytic radical chemistry offered a facile, ambient and effective synthetic strategy to improve the catalytic performances of photocatalytic materials.

Molten salt synthesis of 1T/2H mixed phase MoS2 for boosting photocatalytic H2 evolution via Schottky junction under EY-sensitized system

Clean H2 fuel obtained from the photocatalytic water splitting to hydrogen reaction could efficiently alleviate current energy crisis and the concomitant environmental pollution problems. Therefore, it is desirable to search for a highly efficient photocatalytic system to decrease the energy barrier of water splitting reaction. Herein, the 1T/2H mixed phase MoS2 sample with Schottky junction between contact interfaces is developed through molten salt synthesis for photocatalytic hydrogen production under a dye-sensitized system (Eosin Y-TEOA-MoS2) driven by the visible light. In mixed phase MoS2 sample, the photogenerated electrons of 2H-phase MoS2 migrated to the 1T-phase MoS2 are difficult to jump back because of the existence of Schottky barrier, which greatly suppresses the quenching of EY and therefore results in an enhanced hydrogen evolution performance. Therefore, the optimized MoS2 sample (MoS2-350) has an initial hydrogen evolution rate of 213 μmol h−1 and corresponding apparent quantum yield of 36.1 % at 420 nm, far higher than those of pure Eosin Y. It is strongly confirmed by the steady‐state/time-resolved photoluminescence (PL) spectra and transient photocurrent response experiments. With the assistance of Density functional theory (DFT) calculation, the function of Schottky junction in photocatalytic hydrogen evolution reaction is well explained. In addition, a new and universal method (SVM curve) of judging oxidation or reduction quenching for photosensitizers is proposed.

Role of defects on the electrochemical performance of MnS nanoparticles decorated 2H-MoS2 nanoflower: Experimental and theoretical investigation

We report the influence of MnS nanoparticles on the surface morphological, structural, chemical, and electrochemical performance of 2H-MoS2 nanoflower (MoS2/MnS) produced by a facile hydrothermal method. Morphological study reveals that the incorporation of MnS nanoparticles distorts the lattice fringe and increases the interlayer spacing of the MoS2 nanoflower. XPS analysis reveals a partial conversion from the 2H-MoS2 to 1T- MoS2 together with the formation of defects states in the nanoflower due to the sulfur vacancies created by MnS. The MoS2/MnS nanocomposite provides improved electrochemical performance with a maximum specific capacitance of 351 Fg−1 at a current density of 0.3 Ag−1 and a capacitive retention of 80 % after 8000 charging/discharging cycles. The density functional theory (DFT) revealed defect states formed in forbidden energy regions because of strong hybridization between Mo-d and Mn-d orbitals. The improved electrochemical performance of the MoS2/MnS nanocomposite can be attributed to the defect rich 1T-MoS2 phase, the enlarged surface, and increased interlayer spacing originating from the decoration of MnS nanoparticles. The combined experimental and theoretical approach, together with a facile synthesis technique, will open up an economical route for the fabrication of efficient energy storage devices.

The Effect of Heat Treatment after Hydrothermal Reaction on the Lithium Storage Performance of a MoS2/Carbon Cloth Composite.

In this study, 1T phase MoS2 nanosheets were synthesized on the surface of a carbon cloth via a hydrothermal reaction. After heat treatment, the 1T phase MoS2 was transformed into the 2H phase with a better capacity retention performance. As an anode material for lithium-ion batteries, 2H phase MoS2 on the carbon cloth surface delivers a capacity of 1075 mAh g-1 at a current density of 0.1 A g-1 after 50 cycles; while the capacity of the 1T phase MoS2 on the surface of the carbon cloth without heat treatment fades to 528 mAh g-1. The good conductivity of a carbon cloth substrate and the separated MoS2 nanosheets help to increase the capacity of MoS2 and decrease its charge transfer resistance and promote the diffusion of lithium ions in the electrode.

Integrating configuration, doping and heterojunction into the g-C3N4-based photocatalyst for water splitting

Construction of a highly efficient g-C3N4-based photocatalyst for hydrogen generation is promising but still challenging. In this work, the 1T-phase MoS2 nanosheets are prepared by using supercritical carbon dioxide, which are utilized to build 2D-2D g-C3N4/MoS2 heterojunction for solar H2 generation. In addition, MoS2 is also severed as the precursor of heteroatom to dope into 2D g-C3N4 nanosheets for forming monatomic Mo-doped g-C3N4-based photocatalyst. The obtained single atomic Mo-doped 2D/2D g-C3N4/MoS2 heterojunction exhibits a boosted H2 production of 2222.6 μmol g−1 h−1 with the apparent quantum yield of 9.08%, far exceeding the primitive one. Theoretical calculations and experimental results demonstrate that Mo-PCN/PMS composite possess a Mo-N3 configuration, and the synergy of three promoted strategies, including stripping, doping, and heterojunction plays vital roles in boosting the catalytic activity. This study implies that the integrated g-C3N4-based composite has great potential application in the field of photocatalytic hydrogen evolution.

Phase-incorporation-induced electromagnetic coupling of NFS@1T/2H–MoS2 for enhanced microwave absorption

Herein, we propose a combination strategy to induce robust room-temperature electromagnetic coupling in non-magnetic MoS2 semiconductor (2H–MoS2). The introduction of ascorbic acid (AA) is intended to introduce sulfur vacancies (sv) in the process of 2H–MoS2 nano-sheet shells coating on the surface of three-dimensional (3D) matrix. It promotes the transformation of local lattice (2H–MoS2) into metal phase (1T-MoS2). The transformed 1T-MoS2 phase improves the conductivity (σ) of the composite by 1.48 times. Due to the Mo4+4d energy state within the bandgap, the exchange interaction between the sv and the Mo4+4d bandgap state produces a robust intrinsic electromagnetic response of more than 1.2 emu/g. Density functional theory (DFT) calculations are used to analyze the above results, and a novel electromagnetic-coupling-enhanced microwave absorption mechanism is proposed. The results indicates that microwave absorption performance can be effectively improved by the phase-incorporation effect. The minimum reflection loss (RLmin) reaches −53.1 dB (1.7 mm) and the adjustable effective absorption bandwidth (EAB) covers 14.5 GHz (3.5–18 GHz) at the various matching thicknesses. This work might shed light on a new possibility of manipulating electromagnetic interaction to promote microwave absorption.