Highly conductive, high aspect ratio sulfide nanowires, methods of making and applications thereof

Abstract

The application relates to a high-conductivity high-length-diameter-ratio sulfide nanowire and a preparation method and application thereof. The chemical composition of the sulfide nanowire is Mo2S3, and the crystal phase is monoclinic phase; the diameter of the sulfide nanowire is 200 nm-1000 nm, and the length is 20 mu m-1 mm.

Description

Technical Field

[0001] This invention relates to a high conductivity, high aspect ratio transition metal sulfide nanowire, its preparation method and application, belonging to the field of nanomaterials. Background Technology

[0002] With the increasing popularity of flexible wearable electronic devices, stretchable electronic devices have received growing attention. Flexible stretchable conductors, as the foundation of flexible electronic devices, are a key research focus. Currently, the most common method for preparing stretchable conductors is to composite conductive materials with stretchable materials to form a conductive interpenetrating network. During the stretching process, the conductive fillers in the composite material slide against each other, allowing the conductive material to maintain electronic conductivity even during stretching. Commonly used conductive materials include inorganic conductive nanowires, conductive nanoparticles, conductive films, and conductive polymers. Among these, inorganic conductive nanowires stand out due to their high aspect ratio, enabling them to form interpenetrating connections at relatively low concentrations. Furthermore, their excellent stretchability and high electronic conductivity after being composited with a substrate give them a competitive edge.

[0003] Nanowire materials commonly used in flexible and stretchable conductors include metallic nanowires (such as silver nanowires and copper nanowires) and carbon nanotubes. Metallic nanowires possess high electronic conductivity, but as they are elemental metals, they are prone to reaction with oxygen, sulfur, and chlorine ions in the environment, leading to failure and limiting their applications. Carbon nanotubes exhibit good electronic conductivity and excellent weather resistance; however, their overly stable surface chemical structure makes them difficult to disperse directly in common solvents, thus limiting further processing and shaping. Therefore, finding a high aspect ratio nanowire material that simultaneously satisfies high conductivity, chemical stability, and easy dispersibility has become an urgent problem to be solved. Summary of the Invention

[0004] Therefore, the purpose of this invention is to prepare sulfide nanowire materials with high conductivity, high aspect ratio, and uniform size, as well as their preparation methods and applications.

[0005] On one hand, the present invention provides a conductive sulfide nanowire, wherein the chemical composition of the sulfide nanowire is Mo2S3 and the crystal phase is monoclinic; the diameter of the sulfide nanowire is 200nm to 1000nm and the length is 20μm to 1mm.

[0006] Furthermore, preferably, the electrical conductivity of the sulfide nanowires is ~4.9 × 10⁻⁶. 4 Sm -1 Among them, the intermetallic bonding in Mo2S3 crystal forms electronic transition pathways, giving it high electronic conductivity.

[0007] On the other hand, the present invention provides a method for preparing sulfide nanowires, comprising: (1) A transition metal elemental powder, sulfur elemental powder, molten salt and a structure directing agent are mixed evenly to obtain a reaction precursor; the structure directing agent is elemental phosphorus. (2) The reaction precursor was sealed in a quartz tube and placed in a muffle furnace and sintered at 850℃~1200℃ to prepare sulfide nanowires.

[0008] In this invention, elemental phosphorus is added as a structure guiding agent on the basis of molten salt-assisted solid-phase preparation of Mo2S3. During the growth process, phosphorus is adsorbed on the (100) crystal plane of Mo2S3 crystal, so that it is directionally grown into one-dimensional nanowires.

[0009] Preferably, the molar ratio of the transition metal powder to the sulfur powder is 2:3.

[0010] Preferably, the molten salt is selected from at least one of sodium chloride, sodium bromide, potassium chloride, and potassium bromide; the mass ratio of the molten salt to the total mass ratio of transition metal powder and sulfur powder is 0.5:1 to 20:1.

[0011] Preferably, the mass ratio of the structure-directing agent to the total mass of transition metal powder and sulfur powder is 0.001:1 to 0.1:1, more preferably 0.008:1 to 0.03:1. As the phosphorus content increases from zero to an optimal value (0.03:1), the morphology of Mo2S3 gradually changes from nanosheets to nanowires. However, as the phosphorus content further increases to an excess (e.g., 0.04:1), the morphology of Mo2S3 gradually becomes a mixture of nanowires and nanoparticles.

[0012] Preferably, the atmosphere in the quartz tube is a vacuum or an inert atmosphere.

[0013] Preferably, the sintering heating rate is 1 to 20 °C / min.

[0014] Preferably, the sintering time is 300 to 4000 minutes.

[0015] In another aspect, the present invention provides an application of the above-mentioned sulfide nanowires in wearable devices, energy storage devices, electrocatalysis, stretchable conductors, and flexible sensors.

[0016] Beneficial effects: This invention provides a simple and feasible method for preparing sulfide nanowires with high aspect ratio and uniform size. This method yields highly conductive sulfide nanowires with the chemical composition Mo₂S₃. The Mo₂S₃ nanowires have a diameter of 200 nm to 1000 nm and a length of 20 μm to 1 mm. Their electronic conductivity is 4.9 × 10⁻⁶. 4 S m-1 Due to sulfur end-capping, it exhibits excellent environmental weather resistance and good biocompatibility. Furthermore, its simple preparation method makes it suitable for large-scale production. Attached Figure Description

[0017] Figure 1 The X-ray diffraction pattern of the Mo2S3 sample in Example 1; Figure 2 This is a scanning electron microscope image of the Mo2S3 nanowires in Example 1; Figure 3 The energy spectrum of the Mo2S3 nanowires in Example 1; Figure 4 This is a conductivity-temperature curve of the Mo2S3 nanowires in Example 1 at around 300K; Figure 5 Scanning electron microscope image of Mo2S3 nanomaterials prepared for Comparative Example 1; Figure 6 The image shows a scanning electron microscope image of the Mo2S3 nanomaterials prepared in Example 4. Detailed Implementation

[0018] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0019] The inventors have discovered that transition metal sulfides, as chemically stable materials with tunable band gaps, have attracted widespread attention. Their surfaces exhibit good biocompatibility due to sulfur atom end-capping, and their tunable band gaps enable excellent electrical conductivity. Therefore, the technical problem to be solved by this invention is how to prepare sulfide nanowires with high conductivity, high aspect ratio, and uniform size.

[0020] Therefore, based on the research foundation in the field of solid-state chemistry and combined with the design concept of low-dimensional materials, this invention introduces additional metal atoms between the two-dimensional transition metal sulfide layers, which promotes the formation of conductive pathways in the crystal structure. At the same time, it creatively achieves one-dimensional directional growth through phosphorus-assisted molten salt sintering, and successfully synthesizes sulfide nanowire materials with high electrical conductivity, high aspect ratio and uniform size.

[0021] In this invention, the chemical formula of the sulfide nanowire material with high conductivity, high aspect ratio, and uniform size is Mo2S3, and its crystal structure is P121 / m1 monoclinic.

[0022] This invention combines the design concept of low-dimensional nanomaterials, using phosphorus as a structure directing agent and a molten salt-assisted growth process to achieve the synthesis and preparation of sulfide nanowires with high conductivity and high aspect ratio. The following exemplarily illustrates the preparation method of sulfide nanowire materials.

[0023] Metal elemental powder and sulfur elemental powder are mixed in a molar ratio of 2:3 to obtain the reactant precursor.

[0024] Phosphorus and other substances are added to the reaction precursor as structure directing agents, and molten salt is added as a co-solvent. After grinding them together evenly, the mixture is reacted at 850℃~1200℃ for 300~4000 min.

[0025] The structure-directing agent can be 0.1–10 wt% of the total mass of the reactant precursors. Phosphorus is used as the structure-directing agent, which adsorbs onto a specific surface of the seed crystal during the reaction, causing it to grow in a directional manner into high aspect ratio nanowires.

[0026] The molten salt includes one or more of sodium chloride, sodium bromide, potassium chloride, and potassium bromide. The molten salt can be 50–5000 wt% of the total mass of the reactant precursors.

[0027] The sintering method includes sealed vacuum sintering or sintering under inert atmosphere protection.

[0028] After cooling, the molten salt was dissolved in a large amount of deionized water, then washed three times with deionized water, and dried at 80°C to obtain sulfide nanowires.

[0029] The conductive sulfide nanowires obtained in this invention are applied to energy storage devices, flexible batteries, flexible electronics, stretchable electronics, and flexible sensors.

[0030] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below. In the following examples, unless otherwise specified, the reagents, materials, and instruments used are all conventional reagents, conventional materials, and conventional instruments, all of which are commercially available.

[0031] Example 1 Weigh out 4 mmol of elemental molybdenum powder (0.576 g), 6 mmol of elemental sulfur powder (0.192 g), 0.2 mmol of red phosphorus (0.0062 g) (0.008:1), and 4 g of sodium chloride (500 wt%). Grind the powder for 30 min. Place the ground powder into a quartz glass tube, evacuate, seal with a flame gun, and place in a muffle furnace. Heat to 900 °C at a rate of 5 °C / min and hold for 3000 min. After cooling, soak the prepared sample in 2 L of deionized water for 8 h, then wash three times with deionized water and dry in an oven at 80 °C for 12 h to obtain Mo2S3 nanowire material.

[0032] Powder X-ray diffraction testing of the sample prepared in Example 1 confirmed that it was a pure monoclinic Mo2S3 sample. Figure 1 As shown.

[0033] Using a scanning electron microscope equipped with an energy dispersive spectroscopy (EDS) instrument, the prepared Mo₂S₃ was identified as nanowires with a diameter of 200–600 nm and a length of 50–200 μm. The molar ratio of Mo to S in the nanowires was 2:3. Figure 2 , Figure 3 As shown.

[0034] Using a comprehensive physical property measurement system, the bulk conductivity of the Mo2S3 nanowire sample at 300 K was determined to be 4.9 × 10⁻⁶. 4 S m -1 ,like Figure 4 As shown.

[0035] Example 2 Weigh out 4 mmol of elemental molybdenum powder, 6 mmol of elemental sulfur powder, 0.2 mmol of red phosphorus (0.008:1), and 4 g of sodium chloride (500 wt%), and grind them for 30 min. Place the ground powder in a crucible and put it in a tube furnace. Heat to 900 °C at a rate of 10 °C / min and hold for 3000 min. After cooling, immerse the prepared sample in 2 L of deionized water for 8 h, then wash it three times with deionized water and dry it in an oven at 80 °C for 12 h to obtain Mo2S3 nanowire materials. The diameter of the obtained Mo2S3 nanowires is 100–500 nm, and the length is 10–50 μm.

[0036] Example 3 4 mmol of elemental molybdenum powder, 6 mmol of elemental sulfur powder, 0.04 mmol of red phosphorus (0.016:1), and 6 g of molten salt (500 wt%) of potassium chloride and lithium chloride mixed in a 1:1 mass ratio were weighed and ground for 30 min. The ground powder was then placed in a quartz glass tube, vacuum-sealed, and sealed with a flame gun. The tube was then placed in a muffle furnace and heated to 900 °C at a rate of 5 °C / min, and held at that temperature for 3000 min. After cooling, the prepared sample was immersed in 2 L of deionized water for 8 h, then washed three times with deionized water, and dried in an oven at 80 °C for 12 h to obtain Mo2S3 nanowire materials. The diameter of the obtained Mo2S3 nanowires was 200–600 nm, and the length was 50–200 μm.

[0037] Example 4 Weigh 4 mmol of elemental molybdenum powder, 6 mmol of elemental sulfur powder, 1 mmol of red phosphorus (0.04:1), and 4 g of sodium chloride (500 wt%), grind for 30 min, and place the ground powder into a quartz glass tube. Vacuum the tube, seal it with a flame gun, and place it in a muffle furnace. Heat to 900℃ at a rate of 5℃ / min and hold for 3000 min. After cooling, soak the prepared sample in 2 L of deionized water for 8 h, then wash it three times with deionized water, and dry it in an oven at 80℃ for 12 h to obtain Mo2S3 material. The obtained Mo2S3 is a mixture of nanowires and nanoparticles. The nanowires have a diameter of 100 nm to 5 μm and a length of 30 μm to 1 mm, while the nanoparticles have a diameter of 500 nm to 2 μm. Figure 6 As shown.

[0038] Comparative Example 1 Weigh 4 mmol of elemental molybdenum powder, 6 mmol of elemental sulfur powder, and 4 g of sodium chloride (500 wt%), grind for 30 min, and place the ground powder into a quartz glass tube. Vacuum the tube, seal it with a flame gun, and place it in a muffle furnace. Heat to 900℃ at a rate of 5℃ / min and hold for 3000 min. After cooling, soak the prepared sample in 2 L of deionized water for 8 h, then wash it three times with deionized water, and dry it in an oven at 80℃ for 12 h to obtain Mo2S3 material. The obtained Mo2S3 is urchin-like nanoflowers with a diameter of 30–200 μm. Figure 5 As shown.

[0039] The above embodiments are merely illustrative of the present invention and are not restrictive. Those skilled in the art, inspired by the present invention, can make numerous substitutions or modifications without departing from the fundamental principles and scope of the claims. Any non-essential improvements and adjustments made fall within the scope of protection of the present invention.

Claims

1. A sulfide nanowire, characterized in that, The sulfide nanowires have the chemical composition of Mo2S3 and a monoclinic crystal phase; the diameter of the sulfide nanowires is 200 nm to 1000 nm, and the length is 20 μm to 1 mm; the preparation method of the sulfide nanowires includes: (1) The transition metal powder, sulfur powder, molten salt and structure directing agent are mixed evenly to obtain the reaction precursor; the structure directing agent is elemental phosphorus; (2) The reaction precursor was sealed in a quartz tube and placed in a muffle furnace and sintered at 850℃~1200℃ to prepare sulfide nanowires.

2. The sulfide nanowire according to claim 1, characterized in that, The electrical conductivity of the sulfide nanowires is 4.9 × 10⁻⁶. 4 S m -1 .

3. A method for preparing sulfide nanowires according to claim 1 or 2, characterized in that, include: (1) The transition metal powder, sulfur powder, molten salt and structure directing agent are mixed evenly to obtain the reaction precursor; the structure directing agent is elemental phosphorus; (2) The reaction precursor was sealed in a quartz tube and placed in a muffle furnace and sintered at 850℃~1200℃ to prepare sulfide nanowires.

4. The preparation method according to claim 3, characterized in that, The molar ratio of the transition metal powder to the sulfur powder is 2:

3.

5. The preparation method according to claim 3, characterized in that, The molten salt is selected from at least one of sodium chloride, sodium bromide, potassium chloride, and potassium bromide; the mass ratio of the molten salt to the total mass ratio of transition metal powder and sulfur powder is 0.5:1 to 20:

1.

6. The preparation method according to claim 3, characterized in that, Structure directing agent mass: The total mass of transition metal powder and sulfur powder is 0.001:1 to 0.1:

1.

7. The preparation method according to claim 6, characterized in that, Structure directing agent mass: The total mass of transition metal powder and sulfur powder is 0.008:1 to 0.03:

1.

8. The preparation method according to claim 3, characterized in that, The atmosphere inside the quartz tube is a vacuum or an inert atmosphere.

9. The preparation method according to claim 3, characterized in that, The sintering heating rate is 1-20°C / min, and the sintering time is 300-4000 minutes.

10. The application of the sulfide nanowire according to claim 1 or 2 in energy storage devices, electrocatalysis, stretchable conductors, and flexible sensors.

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