Molybdenum Disulfide Nanosheets Research Articles

Synthesis of Thioglycolic Acid-Modified Molybdenum Disulfide Nanosheets for Electrochemical Sensing and Its Application in Molnupiravir Detection

Abstract In the modern world, population growth, industrialization, and lifestyle changes have led to a rise in existing and new diseases, increasing global drug consumption. Proper pharmaceutical dosage is vital since drugs are only effective within specific concentration ranges. Therefore, developing reliable analytical methods for drug analysis in pharmaceuticals and biological samples is essential. Electroanalytical methods are particularly advantageous due to their low cost, ease of use, and rapid response. This study introduces a highly sensitive electrochemical sensor based on thioglycolic acid (TA)-decorated metallic phase molybdenum disulfide (MP-MoS2) nanosheets for the selective detection of molnupiravir (MOL), an antiviral drug used in Covid-19 treatment. The TA@MP-MoS2 nanomaterial was characterized using FTIR, TEM, and EIS. Screen-printed carbon electrodes (SPCE) were modified with TA@MP-MoS2 nanosheets to evaluate their electro-chemical and catalytic behaviours towards MOL by cyclic voltammetry (CV) and square wave voltammetry (SWV). The sensor displayed a well-defined electro-oxidation signal for MOL at 0.534 V, with the linear responses in two concentration ranges: 0.50 – 3.40 µM and 3.40 – 9.55 µM, and a low detection limit of 22.6 nM. The proposed design that has promising results could be an alternative strategy to fabricate the sensitive sensor for the detection of antiviral agents in real samples

Novel 3S-shaped biophotonic sensor utilizing MoS2–NSs/ZnO–NWs/AuCu–NCs for rapid detection of Shigella flexneri bacteria

This paper describes a unique, extremely sensitive biophotonic sensor with a three-tier S-tapered (3S) structure. It is designed for the real-time detection of Shigella flexneri (S. flexneri), a common foodborne pathogen that causes severe gastrointestinal diseases. The sensor development includes three distinct diameters of S-tapered structures. The performance of tapered sections was improved by using molybdenum disulfide nanosheets (MoS2-NSs), zinc oxide nanowires (ZnO-NWs), and photoluminescent bimetallic gold–copper nanoclusters (AuCu–NCs). These nanoparticles greatly improve the sensor’s performance. The sensor is further functionalized using anti-S. flexneri antibodies, allowing for the precise detection and capture of the target bacterium. The results show that the sensor can detect S. flexneri rapidly and accurately, with a linear detection range of 1–108 colony-forming units per milliliter (CFU/ml) and a low detection limit of 4.412 CFU/ml. In addition, the sensor’s ability to identify S. flexneri biofilms is demonstrated. Biofilm detection allows us to better understand and control biofilm concerns in the environment, equipment, and biomedical devices. Aptamer examines confirm the sensor’s ability to detect S. flexneri from the lateral direction. This study makes a significant contribution to the field of biosensing because no biophotonic sensor has previously been developed specifically for the detection of S. flexneri, fulfilling a critical gap in the arena of food safety and pathogen detection. The 3S sensor’s performance, robustness, and potential for practical applications make it an important addition to the field of photonics.

Sulfated Polysaccharides Mediated Liquid Exfoliation of Molybdenum Disulfide Nanosheets: Preparation and Antibacterial Assessment

Sulfated Polysaccharides Mediated Liquid Exfoliation of Molybdenum Disulfide Nanosheets: Preparation and Antibacterial Assessment

1 T/2 H mixed phase MoS2 nanosheets decorated with Ag nanoparticles for effective photocatalysis of organic dyes for wastewater treatment

The rapid industrialization and urbanization have led to the proliferation of organic dyes in wastewater, necessitating the development of efficient and sustainable treatment technologies. We report here a novel photocatalyst based on 1 T/2 H mixed-phase molybdenum disulfide nanosheets (1 T/2 H-MoS2 NSs) decorated with silver (Ag) nanoparticles for the enhanced photodegradation of both cataionic and anionic organic dyes under natural sunlight. Hydrothermally synthesized silver nanoparticles decorated 1 T/2 H MoS2 nanosheets (Ag-1 T/2 H MoS2 NSs) are characterized through X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Raman spectroscopy, UV–vis spectroscopy, and Photoluminescence (PL) spectroscopy. FESEM results reveal that MoS2 NSs of thickness 17 nm clustered into nanoflowers where Ag nanoparticles are embedded in them. XRD results show the characteristic diffraction peaks at 2ϴ value 9.80 and 32.380 for (002) and (100) planes respectively. Photocatalytic performance has been evaluated by the degradation of Crystal Violet (CV) and Methyl Orange (MO) under direct sunlight irradiation. Nanocomposites exhibit a significant improvement in degradation efficiency i.e. 97 % for both (CV) and (MO) in 15 minutes and 25 minutes respectively compared to pure MoS2. The superior activity of the Ag-1 T/2 H MoS2 composite is attributed to the synergistic effects of the mixed-phase MoS2 structure and the charge transfer phenomenon provided by Ag nanoparticles. This work highlights the potential of Ag-1 T/2 H MoS2 NSs as an effective photocatalyst for the treatment of dye-contaminated wastewater.

An integrated push-to-pull micromechanical device: Design, fabrication, and in-situ experiment

The rapid advancement of micro-nano machining technology has led to a decrease in the dimensions of microdevices and microchips, following the principles of Moore’s law. In addition to conventional semiconductor materials like silicon, emerging nanoscale materials such as nanowires, nanotubes, and two-dimensional materials are being considered as promising alternative constituent materials. The mechanical properties of these materials have a significant impact on the performance and service life of these microdevices and microchips. However, conventional mechanical testing methods have difficulty in accurately measuring the properties of these materials at the nanoscale due to limitations in displacement control and microforce sensing. Consequently, there is an urgent need to develop a micromechanical device capable of testing nanoscale solid materials. In this study, we propose a concept based on high-resolution image sequences for the design of an integrated micromechanical device capable of synchronously measuring the force and deformation of tested specimens. The device has been fabricated using ultrafast femtosecond laser etching technology, which offers an efficient and cost-effective approach for manufacturing microstructures and is suitable for processing various materials such as metals and nonmetals. The stiffness of the device plays a crucial role in the design of the micromechanical device, and a stiffness-matching criterion is introduced to ensure appropriate design parameters. The fabricated device is employed to conduct in-situ tension experiments on SiC nanowires and multilayer molybdenum disulfide nanosheet within a scanning electronic microscope, enabling accurate measurement of their strength, modulus, and fracture strain.

Electrostatically Self-Assembled Magnetic Nanoparticles for High-Temperature Resistant and Friction-Controlled Lubrication System.

Magnetic-responsive surfactants are considered promising smart lubricating materials due to their significant stimulation response to applied magnetic fields. In this study, four magneto-responsive surfactants are successfully fabricated and encapsulated on the surface of molybdenum disulfide nanosheets (MoS2@C18H37N+(CH3)3[XCl3Br]-, X=Fe, Ce, Gd, and Ho) as base-oil components using electrostatic self-assembly, thereby constructing a multi-functional magnetic lubrication system (MoS2@STAX). Magnetorheological measurements confirm the remarkable responsiveness of MoS2@STACe lubricants at high shear rates and applied magnetic fields, which is further corroborated by the constant proximity of the magnet. The formation of dense carbon and tribo-chemical films between the friction interfaces at elevated temperatures is the primary factor contributing to the significant reduction in frictional wear. Notably, the magnetic lubricant demonstrates a pronounced response behavior when subjected to an applied magnetic field in the ceramic tribopair, even at lower magnetic fields. This work presents concepts for the development of high-temperature resistant and tunable lubrication additives by designing the material structure and controlling the magnetic stimulation.

Development of Amphiphilic Janus Molybdenum Disulfide Nanosheets and Their Application for Enhanced Oil Recovery

Development of Amphiphilic Janus Molybdenum Disulfide Nanosheets and Their Application for Enhanced Oil Recovery

Unlocking epoxy thermal management capability via hierarchical Ce-MOF@MoS2 hybrid constructed by in-situ growth method

This study demonstrates the preparation of needle-like Ce-MOF crystals on molybdenum disulfide (MoS2) nanosheets using in-situ growth technology. This hybrid structure significantly enhances the thermal management and mechanical properties of thermosetting epoxy resin (EP). Specifically, EP/Ce-MOF@MoS2-3 exhibits a notable increase in tensile strength (TS) to 50.87 MPa and elongation at break (EB) to 10.84 %. Moreover, Ce-MOF@MoS2 provides synergistic flame retardant benefits, reducing the peak heat release rate (pHRR) and total heat release (THR) of EP/Ce-MOF@MoS2-3 by 38 % and 12.64 %, respectively, compared to EP-0. Additionally, Ce-MOF@MoS2 suppresses smoke and reduces toxic emissions; at a 3 % loading, it decreases CO and CO2 production in EP nanocomposites by 48.8 % and 38.7 %, respectively. Thus, this Ce-MOF@MoS2 hybrid, synthesized via in-situ growth, offers a novel approach for developing EP nanocomposites with superior thermal management and mechanical properties, along with effective flame retardancy and reduced hazardous emissions during thermal events.

MoS2@Ti3C2Tx Heterostructure: A new negative electrode material for Li-Ion hybrid supercapacitors

Lithium-ion hybrid supercapacitors (LHSCs) demonstrate promising electrochemical performance, including long cyclic stability and a high-power density. However, their limited energy density has restricted the development towards commercialization. In this work, a novel heterostructure (HS) has been introduced based on molybdenum disulfide (MoS2) nanosheets (NSs) anchored on the surface of exfoliated layers of titanium carbide (Ti3C2Tx) MXenes. The prepared negative electrode material named as MoS2@Ti3C2Tx–HS holds substantial promise for advancing LHSCs to enhance energy density. The MoS2@Ti3C2Tx–HS demonstrates outstanding pseudocapacitive performance in a three-electrode system by achieving a capacitance of 1022.7 F g−1 at 1 A g−1. It exhibited a stable cyclic life (5,000 cycles) and retained 97.02 % of its initial capacitance. Theoretical calculations based on density functional theory (DFT) show impressive results to support the experimental work. The calculated density of states (DOS), band structures, adsorption energies (Eads), and diffusion energy demonstrate that MoS2@Ti3C2Tx–HS possesses excellent electronic and adsorption properties. The fabricated MoS2@Ti3C2Tx–HS//CP–LHSCs device shows a high capacitance of 153.75 F g−1 at 2 A g−1, with stable cyclic life (94.5 %) over 10,000 cycles. Furthermore, it shows a notable high energy density of 54.7 Wh kg−1 at a power density of 1,601.3 W kg−1. The prepared MoS2@Ti3C2Tx–HS electrode, with its synergistic combination, stands out as an auspicious material, showing remarkable electrochemical performance and paving the way for LHSCs.

Preparation of MoS2 nanosheets/nitrogen-doped carbon nanotubes/MoS2 nanoparticles and their electrochemical energy storage properties

Inferior electrical conductivity, huge volume swell, shuttle effect and slow redox reactions in Li-S batteries restrict their practical applications. In this study, molybdenum disulfide nanosheets anchored on nitrogen-doped carbon nanotubes encapsulating molybdenum disulfide nanoparticles (MoS2/NC/MoS2 NTs) were prepared by heat treatment, ammonia etching, high-temperature sulfurization, and solvent-thermal in-situ growth using polypyrrole-coated molybdenum trioxide nanorods (MoO3 NRs) as templates. The hollow structure of nitrogen-doped carbon nanotubes and the high specific surface area are conducive to increasing sulfur loading, increasing the contact area of electrolyte, accelerating the electron transport, and shortening the lithium ion transport route. The MoS2 nanosheets on the outer layer of the nitrogen-doped carbon tubes and the MoS2 particles wrapped inside can anchor polysulfides by chemisorption, slowing down the shuttle effect and enhancing the energy storage performance of lithium-sulfur batteries. The MoS2/NC/MoS2/S nanotubes (MoS2/NC/MoS2/S NTs) maintain a capacity of 498.9 mAh g−1 over 500 cycles at 1.0 A g−1, with an average single-cycle capacity decay rate of 0.061 %. The density functional theory calculations, the adsorption experiments, and the X-ray photoelectron spectroscopy results all confirm that the MoS2/NC/MoS2 NTs are able to anchor lithium polysulfides through strong adsorption, thus effectively mitigating the shuttle effect of polysulfides. The synthesis of MoS2/NC/MoS2/S NTs in this study is of important significance for the development of advanced lithium-sulfur batteries.

Vanadium Molybdenum Disulfide Nanosheets Anchoring on Carbon Cloth as High-Energy Density Cathode for Magnesium-Lithium Hybrid Batteries.

Magnesium-lithium-ion hybrid batteries (MLIBs) have gained significant attention since the combination of a dendrite-free and low-cost magnesium anode with lithium-ion storage cathodes. However, the lack of high-performance cathodes has severely hindered their development, limited by the lower operating voltages of electrolytes. Herein, vanadium molybdenum disulfide nanosheets anchoring on flexible carbon cloth (VMS@CC) are constructed as high-performance cathodes for MLIBs, which inherit the electrochemical properties of high-voltage VS2 and high-capacity MoS2, simultaneously. By adjusting the V and Mo atomic ratio, the VMS@CC cathode for MLIBs delivers a record maximum energy density of 275.5 Wh kg-1 with a high working voltage of 1.07 V at 50 mA g-1. Meanwhile, under the synergistic effects of the conductive carbon cloth matrix, abundant hetero-interfaces and defects, as well as expanded interlayer spacing, the VMS@CC cathode displays superior rate capability and long-term cycling stability. Ex situ analyses demonstrate the VMS nanosheets cathode exhibits a Li+/Mg2+ co-insertion/extraction mechanism in MLIBs, following the in situ insertion of organic species in the hybrid electrolyte during the aging process. The fabricated flexible cathode herein provides a new insight into the construction of high-energy density cathodes for MLIBs.

Humic acid changes effect of naturally occurring oxidants on the environmental transformation of molybdenum disulfide nanosheets

2H-phase molybdenum disulfide (2H-MoS2) has been considered to be a chemically stable two-dimensional (2D) nanomaterial. Nonetheless, the persistence of 2H-MoS2 in the presence of environmental redox-active matrices, such as naturally occurring oxidants (e.g., manganese dioxide (MnO2)) and natural organic matter (NOM), remains largely unknown. Herein, we examined the interplay between 2H-MoS2, MnO2 (a common natural oxidant), and NOM species (i.e., Aldrich humic acid (ALHA) and Suwannee River natural organic matter (SRNOM)). The results show that MnO2 accelerates the oxidative dissolution of 2H-MoS2, regardless of the presence of dissolved oxygen. The effect of NOM on the MnO2-induced fate of 2H-MoS2 was found to depend on its affinity for 2H-MoS2 and the functionality of NOM. ALHA preferentially adsorbed on hydrophobic 2H-MoS2 nanosheets due to the enrichment of reductive polycyclic aromatics and polyphenolic constituents. The preferential ALHA adsorption counteracted the MnO2-triggered oxidative transformation of 2H-MoS2, as revealed by the cathodic response of 2H-MoS2 (i.e., decreased the open circuit potential by 0.0338 V) and the emergence of reductive Mo‒C bonds at 228.8 and 231.9 eV upon the addition of ALHA. This work evaluated the persistence of 2H-MoS2, illustrating its susceptibility to decomposition by naturally occurring oxidants and the influence of NOM on it. These findings are crucial for revealing the fate and transport of MoS2 in aquatic environments and provide guidelines for related applications in natural or engineered systems for MoS2 and potentially other 2D materials.

Molybdenum Disulfide Nanosheet-Based Nanocomposite for the Topical Delivery of Umbelliferone: Evaluation of Anti-inflammatory and Analgesic Potentials.

This study aimed to develop a nanocomposite formulation comprising umbelliferone (UMB) and molybdenum disulfide (MoS2) nanosheets as a carrier, termed as the UMB-MoS2 nanocomposite in gel for topical delivery. MoS2 nanosheets were successfully synthesized via a green-hydrothermal reaction of 10 mg of ammonium molybdate and 10 mg of thiourea in 80 mL of deionized water under predetermined conditions. The UMB-MoS2 nanocomposite was prepared by sonicating UMB and MoS2 nanosheets (each of 1 mg/mL) in dimethylformamide. Scanning electron microscopy revealed crumpled nanosheets with an open-ended structure and a nanocomposite as a layered structure. The X-ray diffraction pattern revealed the amorphous nature of UMB in the UMB-MoS2 nanocomposite. Fourier-transform infrared spectra of the UMB-MoS2 nanocomposite had modified bands of the functional group, which confirmed the formation of the nanocomposite. The size and polydispersity-index (435 nm and 0.415, respectively) of the nanocomposite were within the limit for an efficient topical application. Carbopol 934 (2%) was used to prepare the UMB-MoS2 nanocomposite gel (F1) and UMB-Carbopol gel (F2, for comparative evaluation). The pH, spreadability, and viscosity of F1 were found to be 5.56, 5.89 g·cm/s, and 32.5 Pa-sec, respectively, which were optimal for the topical application of gel-based formulations. In vitro release characteristics of both formulations were deemed to be suitable for topical application, where F1 exhibited a biphasic drug release profile and a superior release rate of 94.8% compared to 43.5% for F2 at 24 h. In the carrageenan-induced rat paw edema model, the animal group treated with F1 demonstrated the lowest increase in paw thickness of 26.6%, which was significantly lower as compared to the F2-treated group (52.9%) and the diclofenac sodium-treated group (32.2%). Similarly, in the tail immersion method, F1 exhibited the highest peak tail withdrawal latency of 10.9 s, significantly greater than F2 (8.9 s) and standard treatment (10 s), indicating the superior analgesic activity of F1. This pioneering work introduces a novel UMB-MoS2 nanocomposite with promising anti-inflammatory and analgesic potentials, paving the way for further research into the biomedical applications of MoS2-based nanocarriers.

Scalable 2D Semiconductor‐Based van der Waals Heterostructure Interface with Built‐in Electric Field for Enhanced Electrochemical Water Splitting

Electrochemical water splitting has received tremendous attention as an eco‐friendly approach to produce hydrogen. Noble metals and their oxides are commonly used as electrocatalysts to reduce activation energy barriers for hydrogen and oxygen evolution reactions in high‐performance electrodes, but their cost, scarcity, and limited stability hinder widespread adoption of electrochemical water splitting. Further advancements are therefore needed to reduce reliance on noble metals and improve the long‐term stability. Herein, solution‐processed 2D van der Waals (vdW) p–n heterostructures as an interfacial layer between catalysts and the electrode are introduced to enhance the catalytic performance. These heterostructures are formed by sequentially assembling electrochemically exfoliated black phosphorus and molybdenum disulfide nanosheets into electronic‐grade p‐ and n‐type semiconductor thin films, with the scalability extending across tens‐of‐centimeter scale areas. Benefiting from the charge distribution and built‐in electric field developed upon heterojunction formation, the vdW heterostructure interfacial layer increases both the catalytic activity and stability of commercial Pt/C and Ir/C catalysts compared to when these catalysts are directly loaded onto electrodes. Additionally, the vdW heterostructure also serves as a template for synthesizing nanostructured Pt and Ir catalysts through electrodeposition, further enhancing the catalytic performance in terms of mass activity and stability.

Polydiolcitrate-MoS2 Composite for 3D Printing Radio-Opaque, Bioresorbable Vascular Scaffolds.

Implantable polymeric biodegradable devices, such as biodegradable vascular scaffolds, cannot be fully visualized using standard X-ray-based techniques, compromising their performance due to malposition after deployment. To address this challenge, we describe a new radiopaque and photocurable liquid polymer-ceramic composite (mPDC-MoS2) consisting of methacrylated poly(1,12 dodecamethylene citrate) (mPDC) and molybdenum disulfide (MoS2) nanosheets. The composite was used as an ink with microcontinuous liquid interface production (μCLIP) to fabricate bioresorbable vascular scaffolds (BVS). Prints exhibited excellent crimping and expansion mechanics without strut failures and, importantly, with X-ray visibility in air and muscle tissue. Notably, MoS2 nanosheets displayed physical degradation over time in phosphate-buffered saline solution, suggesting the potential for producing radiopaque, fully bioresorbable devices. mPDC-MoS2 is a promising bioresorbable X-ray-visible composite material suitable for 3D printing medical devices, such as vascular scaffolds, that require noninvasive X-ray-based monitoring techniques for implantation and evaluation. This innovative biomaterial composite system holds significant promise for the development of biocompatible, fluoroscopically visible medical implants, potentially enhancing patient outcomes and reducing medical complications.

Flexible and wearable sensor for in situ monitoring of gallic acid in plant leaves

Gallic acid (GA) is one of the main phenolic components naturally occurring in many plants and foods and has been a subject of increasing interest owing to its antioxidant and anti-mutagenic properties. This study introduces a novel flexible sensor designed for in situ detecting GA in plant leaves. The sensor employs a laser-induced graphene (LIG) flexible electrode, enhanced with MXene and molybdenum disulfide (MoS2) nanosheets. The MXene/MoS2/LIG flexible sensor not only demonstrates exceptional mechanical properties, covering a wide detection range of 1–1000 μM for GA, but also exhibits remarkable selectivity and stability. The as-prepared sensor was successfully applied to in situ determination of GA content in strawberry leaves under salt stress. This innovative sensor opens an attractive avenue for in situ measurement of metabolites in plant bodies with flexible electronics.

Sacrificial MoS2-Polyelectrolyte membranes for fouling control in nanofiltration and reverse osmosis

Sacrificial membranes have emerged as a promising solution to mitigate membrane fouling through their ability to be removed and regenerated while preserving membrane integrity and performance. In this study, we synthesized sacrificial trilayers on a commercial polyamide nanofiltration membrane using layer-by-layer (LbL) assembly of two-dimensional molybdenum disulfide (MoS2) nanosheets and polyelectrolytes. Quartz crystal microbalance with dissipation (QCM-D) studies showed the trilayers to be MoS2-dominant by mass and have a total areal density of 2.37 μg/cm2 after the deposition of two trilayers. The trilayer membrane showed a slight decrease in water permeability and an increase in calcium chloride rejection compared to the pristine nanofiltration membrane. The trilayer membrane demonstrated improved organic fouling resistance over the pristine nanofiltration membrane, maintaining permeability throughout six consecutive cycles. Interestingly, the trilayer membrane after gypsum scaling exhibited sacrificial layer removal and permeability recovery with simple hydraulic cleaning. This suggests the potential for membrane regeneration and sustained fouling resistance that may be achieved by utilizing disruptive interactions with the trilayer materials. In conclusion, sacrificial membranes made of MoS2 nanosheets and polyelectrolytes exhibited excellent organic and inorganic fouling resistance and promising potential for layer removal and regeneration.

Ethoxylated molybdenum disulphide based nanofluid for enhanced oil recovery

Despite advances in renewable energy sources, the world's current infrastructure and consumption patterns still heavily depend on crude oil. Enhanced oil recovery (EOR) is a crucial method for significantly increasing the amount of crude oil extracted from mature and declining oil fields. Nanomaterials have shown great potential in improving EOR methods due to their unique properties, such as high surface area, tunable surface chemistry, and the ability to interact at the molecular level with fluids and rock surfaces. This study examines the potential use of incorporating ethoxylated molybdenum disulfide with a unique three-dimensional flower-like morphology for overcoming the challenges associated with oil recovery from reservoirs characterized by complex pore structures and low permeability. The synthesized nanomaterial features a chemical composition that encompasses a polar ethoxy group linking molybdenum disulfide nanosheets and an alkylamine chain. The ethoxy group promotes interactions with water molecules through hydrogen bonding and electrostatic forces, disrupting the cohesive forces among water molecules and reduction surface tension at the oil–water interface. As a result, the nanomaterial achieves an ultra-low interfacial tension of 10−3 mN/m. Core flooding experiments demonstrate a significant oil recovery of approximately 70% at a concentration as low as 50 ppm. This research paves the way for the design and synthesis of advanced extended surfactant-like nanomaterials, offering a promising avenue for enhancing oil recovery efficiency.

Exfoliated 2D Nanosheet-Based Conjugated Polymer Composites with P-N Heterojunction Interfaces for Highly Efficient Electrocatalytic Hydrogen Evolution.

They have achieved a significant breakthrough in the preparation and development of two-dimensional nanocomposites with P-N heterojunction interfaces as efficient cathode catalysts for electrochemical hydrogen evolution reaction (HER) and iodide oxidation reaction (IOR). P-type acid-doped polyaniline (PANI) and N-type exfoliated molybdenum disulfide (MoS2) nanosheets can form structurally stable composites due to formation of P-N heterojunction structures at their interfaces. These P-N heterojunctions facilitate charge transfer from PANI to MoS2 structures and thus significantly enhance the catalytic efficiency of MoS2 in the HER and IOR. Herein, by combining efficient sodium-functionalized chitosan-assisted MoS2 exfoliation, electropolymerization of PANI on nickel foam (NF) substrate, and electrochemical activation, controllable and scalable Na-Chitosan/MoS2/PANI/NF electrodes are successfully constructed as non-noble metal-based electrochemical catalysts. Compared to a commercial platinum/carbon (Pt/C) catalyst, the Na-Chitosan/MoS2/PANI/NF electrode exhibits significantly lower resistance and overpotential, a similar Tafel slope, and excellent catalytic stability at high current densities, demonstrating excellent catalytic performance in the HER under acidic conditions. More importantly, results obtained from proton exchange membrane fuel cell devices confirm the Na-Chitosan/MoS2/PANI/NF electrode exhibits a low turn-on voltage, high current density, and stable operation at 2 V. Thus, this system holds potential as a replacement for Pt/C with feasibility for applications in energy-related fields.

Enriching the active sites of nanosheets assembled as flower-like MoS2 microstructure by controllable morphology for electrochemical hydrogen evolution reaction

With their tunable electronic structure, transition metal dichalcogenides offer a high surface area and enhanced active sites, making them a promising electrocatalyst for hydrogen production techniques. However, restacking of 2D layers and particle aggregation during material preparation negate its advantages. Herein, we developed a flower-like morphology with numerous molybdenum disulfide (1T/2H MoS2) nanosheet petals. The final formation and arrangements of MoS2 were validated through three distinct approaches: air (AD-M), vacuum (VD-M), and freeze-drying (FD-M). Interestingly, the drying phenomenon effectively alters the stacking and aggregation between the flower petals in the MoS2 and the electrocatalytic activity. Among the different drying processes, the FD-M exhibits minimal stacking and agglomeration between the nanoflowers. The FD-M exhibits remarkable catalytic activity in 1 M KOH for HER, reaching 10 mA cm−2 at a low overpotential (η10) of 198 mV and a small Tafel slope of 58.5 mV dec−1, which is lower than the AD-M (228 mV) and VD-M (215 mV). The FD process modulates the electronic structure of MoS2 by lowering stacking between layers, which effectively increases the ECSA and boosts the HER performance.