A method for preparing porous molybdenum disulfide based on ice crystal templating method

Abstract

The application discloses a preparation method of porous molybdenum disulfide based on an ice crystal template method, which comprises the following steps: adding ammonium molybdate and ammonia water into deionized water, adding citric acid and sodium chloride to prepare a precursor solution, performing freeze-drying treatment, calcination treatment and washing and drying treatment on the precursor solution to prepare MoO3, taking the MoO3 as a molybdenum source, taking thiourea as a pure sulfur source, taking a mixture of deionized water and ethanol as a mixed solvent, and performing sulfuration reaction to prepare MoS2. The application solves the technical problem of group aggregation and pore collapse in the calcination process of the preparation of the MoO3 template, and the porous structure MoS2 prepared by the sulfuration reaction of high-purity sulfur is a multilayer sheet structure, is uniform in form, has excellent specific surface area and rich pore structure. Since the MoS2 has a self-supporting performance, can be directly contacted with a substrate for loading, and effectively improves the catalytic performance of the MoS2.

Description

[0001] This patent is a divisional application of invention 202511705055.7, entitled "A method for preparing porous molybdenum disulfide nanocatalytic materials". Technical Field

[0002] This invention relates to the field of catalytic material preparation technology, specifically to a method for preparing porous molybdenum disulfide based on the ice crystal template method. Background Technology

[0003] Electrocatalytic water splitting is considered one of the most promising and feasible hydrogen production technologies, with highly efficient electrocatalysts being the core technology. Currently, highly efficient electrocatalysts are mainly platinum-based and other noble metal catalysts. However, the high cost and scarcity of platinum limit its large-scale utilization. Therefore, developing inexpensive non-noble metal-based electrocatalysts is essential. Molybdenum disulfide (MoS2) is a novel compound with excellent dispersion properties, diamagnetic properties, rectification, and energy conversion functions. It is abundant and possesses unique electrochemical stability due to its electronic structure. Molybdenum disulfide exhibits excellent hydrodesulfurization performance and is one of the active components in modern industrial hydrogenation catalysts, considered a potential alternative to noble metal-based catalysts.

[0004] Previous studies have shown that the layered edges of two-dimensional MoS2 are generally considered to be active sites for hydrogen production, with a Gibbs free energy for hydrogen adsorption close to zero, while the two-dimensional plane is inert. A direct way to improve the catalytic performance of MoS2 is to create abundant edge sites within it.

[0005] To date, various methods have been employed to endow MoS2 with more edge active sites, such as vertical growth and graphene loading. While numerous methods exist, some require complex preparation processes, while others necessitate expensive substrate materials, significantly limiting the large-scale application of MoS2. Furthermore, the electrocatalytic hydrogen production efficiency of currently obtained MoS2 catalytic materials still needs improvement. Therefore, exploring simplified preparation processes and enabling two-dimensional MoS2 catalytic materials to possess high edge active sites and high catalytic activity is crucial for the development of electrocatalytic hydrogen production technology. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing porous molybdenum disulfide nanocatalytic materials based on the ice crystal template method. This method produces MoS2 nanomaterials with abundant edge active sites, thereby improving the catalytic performance of the material.

[0007] The objective of this invention is achieved through the following technical solution: A method for preparing porous molybdenum disulfide based on the ice crystal template method is characterized by: preparing MoO3 using the ice crystal template method, then using MoO3 as the molybdenum source, thiourea as the pure sulfur source, and a mixture of deionized water and ethanol as the mixed solvent, and obtaining MoS2 through a sulfidation reaction. Specifically, the ice crystal template method involves sequentially adding ammonium molybdate and ammonia to deionized water, mixing them evenly, and then sequentially adding citric acid and sodium chloride to prepare a precursor solution. The precursor solution is then freeze-dried to obtain a precursor, which is then calcined and washed and dried to obtain MoO3.

[0008] Furthermore, the ratio of ammonium molybdate, citric acid, sodium chloride, and deionized water in the precursor solution is 1 g: 1.3~1.5 g: 4~5 g: 20 mL, the volume ratio of deionized water to ammonia is 10: 0.1~0.2, and the mass concentration of ammonia is 25~28%.

[0009] Furthermore, the freeze-drying process involves placing the precursor liquid in liquid nitrogen for 5-8 minutes to freeze it into a solid state, and then freeze-drying it at -45 to -55 °C and 15 to 25 Pa for 40 to 48 hours to obtain the precursor.

[0010] The ice crystal template method is a recognized effective means of synthesizing porous materials. It utilizes the principle of phase separation to freeze-dry frozen samples. The ice crystals undergo solid-liquid-gas three-phase transformation, sublimate into water vapor, and are extracted from the system. At the same time, the colloidal particles involved in the arrangement of ice crystals are retained, and finally a porous structure with a specific orientation is obtained.

[0011] Improper freezing can lead to uneven large pores and an increase in collapsed pores. In this invention, the method of rapid freezing in nitrogen followed by freeze-drying at low temperature changes the solidification behavior of the dispersion medium and the interaction between the solid-liquid interface and the particles, thereby affecting the pore morphology formed by directional freezing. This results in pores that are mainly through-holes, with a more ordered structure that does not collapse.

[0012] Furthermore, the calcination involves calcining the precursor obtained from freeze-drying at 280~310 °C for 1.5~2 h.

[0013] Furthermore, the calcination involves first calcining the freeze-dried precursor at 220-250°C for 30-40 min, and then calcining it at 280-310°C for 1.5-2 h.

[0014] In the preparation of MoO3 using the ice crystal template method, it was found that the calcination temperature for ammonium molybdate to generate MoO3 is typically above 400℃. Higher calcination temperatures lead to structural collapse in the resulting MoO3 template, and the resulting template has an undesirable pore structure, resulting in poor catalytic performance of the subsequent sulfidation synthesis of MoS2. However, lower calcination temperatures result in lower purity MoO3 with more impurities and the formation of a large amount of metastable molybdenum compound mesophases, which also negatively impacts the catalytic performance of subsequent MoS2 preparation.

[0015] In this invention, citric acid and sodium chloride are used as additives during the preparation of the precursor solution. However, due to the low carbonization temperature of citric acid, it decomposes rapidly during calcination, leading to pore collapse, low porosity, and unsatisfactory specific surface area in the generated MoO3. Therefore, ammonia is added in this invention. Some of the citric acid and ammonia in the system preferentially generate ammonium citrate. During calcination, ammonium citrate decomposes at a lower temperature to generate carbon dioxide and ammonia, forming initial micropores in the precursor. Then, the citric acid that has not reacted with ammonia further decomposes at a higher temperature, expanding the micropores and forming a microporous-mesoporous composite structure, which improves the O2 permeation efficiency. Secondly, the citrate ions generated under the action of ammonia effectively react with Mo... 6+ A more stable chelated structure is formed, effectively inhibiting particle aggregation while continuously and slowly decomposing. At a low calcination temperature of 280~310℃, the coordination framework is completely broken, and under the action of NaCl and in a sufficient O2 environment, it is rapidly oxidized to generate MoO3. This also ensures that NaCl crystals are retained in specific positions in the system and eluted during subsequent washing, thus forming a hierarchical pore structure in the system, increasing the specific surface area of ​​MoO3 and enriching its pore structure. The additive citric acid decomposes through a hierarchical reaction, solving the problem of MoO3 structural collapse, while effectively fixing the sodium chloride crystals and molybdate structure. The addition of ammonia, citric acid, and sodium chloride changes the viscosity and surface tension of the precursor solution, while also adjusting the pH environment of the precursor solution. Combined with the calcination treatment, changes occur in the growth, sublimation kinetics, and thermodynamics of each component in the precursor solution, promoting the formation of uniformly dispersed pure-phase MoO3 porous material from molybdate at a lower calcination temperature.

[0016] Furthermore, the washing and drying process involves adding the calcined precursor to deionized water, centrifuging at 5000-6000 rpm, collecting the solid components, adding water and repeating the centrifugation 2-3 times, and then collecting the solid components and drying them at 60 °C for 4-5 h.

[0017] Furthermore, the ratio of MoO3, thiourea, and the mixed solvent is 0.14~0.15 g: 0.07~0.08 g: 30 mL, and the volume ratio of deionized water to ethanol in the mixed solvent is 1:2.

[0018] Furthermore, the temperature of the sulfidation reaction is 170~190 ℃, and the reaction time is 20~24 h.

[0019] Most specifically, a method for preparing porous molybdenum disulfide based on the ice crystal template method is characterized by comprising the following steps: Step (I) Preparation of MoO3 (1) Preparation of precursor solution Ammonium molybdate is added to deionized water and dissolved. Ammonia is then added and mixed thoroughly. After the solution becomes clear, citric acid and sodium chloride are added sequentially and ultrasonically mixed until homogeneous to prepare a precursor solution. The ratio of the amount of ammonium molybdate, citric acid, and sodium chloride to deionized water is 1 g: 1.3~1.5 g: 4~5 g: 20 mL, the volume ratio of deionized water to ammonia is 2:0.1~0.2, and the mass concentration of ammonia is 25~28%. (2) Freeze-drying treatment The precursor solution was placed in an aluminum can, and the aluminum can was placed in liquid nitrogen and frozen for 5-8 min. After the precursor solution was frozen to a solid state, it was freeze-dried at -45 to -55 °C and 15 to 25 Pa for 40 to 48 h to obtain the precursor. (3) Calcination, washing and drying treatment The precursor was first calcined at 220-250℃ for 30-40 min, and then calcined at 280-310℃ for 1.5-2 h. The calcined precursor was added to deionized water and centrifuged at 5000-6000 rpm. The solid components were collected, and water was added again and the centrifugation was repeated 2-3 times. The solid components were then collected and dried at 60℃ for 4-5 h to obtain MoO3. Step (II) Preparation of MoS2 The MoO3 and thiourea prepared in step (I) were added to a mixed solvent consisting of deionized water and ethanol. After mixing evenly, a sulfidation reaction was carried out. Specifically, the reaction was carried out at 170~190℃ for 1.5~2.5 h. The ratio of the amount of MoO3, thiourea and mixed solvent was 0.14~0.15g:0.07~0.08g:30mL. The volume ratio of deionized water and ethanol in the mixed solvent was 1:2. After the reaction was completed, the solid components were collected and dried at 60℃ to obtain MoS2 nanomaterials.

[0020] In this invention, the addition of citric acid and ammonia improves the ice growth kinetics and the topology of the solid-liquid interface, thereby reducing the liquid-solid phase free energy of surface thermodynamics to promote interlayer bridging, which is beneficial to enhancing the mechanical properties of porous MoO3 materials.

[0021] The present invention has the following technical effects: This invention prepares porous MoO3 using an ice crystal template method, and then uses it as a template to prepare porous MoS2 through a sulfidation reaction with high-purity sulfur. This solves the technical problem of agglomeration and pore collapse during the calcination process of MoO3 template preparation. The prepared MoS2 has a multi-layered, plate-like structure with uniform morphology, excellent specific surface area, and abundant pore structure. Because MoS2 has self-supporting properties, it can be directly loaded onto the substrate without the need for coating, thus reducing the interference of binders and other components on catalytic performance and effectively improving the catalytic performance of MoS2. Attached Figure Description

[0022] Figure 1 Comparison of physical samples of MoO3 and MoS2 prepared in Example 1 of this invention: (a) is MoO3, and (b) is MoS2.

[0023] Figure 2 XRD diffraction patterns of MoO3 and MoS2 prepared in Example 1 of this invention.

[0024] Figure 3 Scanning electron microscope (SEM) images of MoS2 prepared in Example 1 of this invention, (a) at low magnification and (b) at high magnification.

[0025] Figure 4 Transmission electron microscope (TEM) images of MoS2 nanomaterials prepared in Example 1 of this invention, (a) at low magnification and (b) at high magnification.

[0026] Figure 5 Scanning electron microscope (SEM) images of MoS2 prepared in Comparative Examples 1, 2 and 3: (a) Low magnification of Comparative Example 1, (b) High magnification of Comparative Example 1; (c) Low magnification of Comparative Example 2, (d) High magnification of Comparative Example 2; (e) Low magnification of Comparative Example 3, (f) High magnification of Comparative Example 3.

[0027] Figure 6 Scanning electron microscope (SEM) images of MoS2 from Examples 2 and 3: (a) is low magnification of Example 2, (b) is high magnification of Example 2, (c) is low magnification of Example 3, and (d) is high magnification of Example 3.

[0028] Figure 7 : Specific surface area curves (BET) for each sample.

[0029] Figure 8 Electrochemical polarization curves (LSV) of each sample. Detailed Implementation

[0030] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0031] Example 1 A method for preparing molybdenum disulfide nanomaterials based on the ice crystal template method includes the following steps: Step (I) Preparation of MoO3 (1) Preparation of precursor solution Ammonium molybdate was added to deionized water and dissolved. Ammonia was then added and mixed thoroughly. After the solution became clear, citric acid and sodium chloride were added sequentially and ultrasonically mixed to prepare a precursor solution. The ratio of the amount of ammonium molybdate, citric acid, sodium chloride, and deionized water was 1 g: 1.4 g: 4 g: 20 mL. The volume ratio of deionized water to ammonia was 2:0.15, and the mass concentration of ammonia was 25%. (2) Freeze-drying treatment The precursor liquid was placed in an aluminum can, and the aluminum can was placed in liquid nitrogen and frozen for 6 min. After the precursor liquid was frozen to solid, it was freeze-dried at -50 ℃ and 20 Pa for 48 h to obtain the precursor. (3) Calcination, washing and drying treatment The precursor was first calcined at 240℃ for 35 min, and then calcined at 300℃ for 2 h. The calcined precursor was added to deionized water and centrifuged at 5500 rpm. The solid components were collected, and water was added again and the centrifugation was repeated twice. The solid components were then collected and dried at 60℃ for 5 h to obtain MoO3. Step (II) Preparation of MoS2 The MoO3 and thiourea prepared in step (I) were added to a mixed solvent consisting of deionized water and ethanol. After mixing evenly, a sulfidation reaction was carried out, specifically at 180°C for 2 h. The ratio of the amount of MoO3, thiourea and the mixed solvent was 0.15 g: 0.075 g: 30 mL, and the volume ratio of deionized water and ethanol in the mixed solvent was 1:2. After the reaction was completed, the solid components were collected and dried at 60°C to obtain MoS2 nanomaterials.

[0032] The MoO3 and MoS2 prepared in this embodiment are as follows: Figure 1 As shown, (a) is MoO3 and (b) is MoS2. It can be seen that the MoO3 sample is a white powder, while the color of MoS2 prepared using MoO3 as a template changes from white to black.

[0033] The MoO3 and MoS2 samples prepared in this embodiment were tested by XRD, and the results are as follows: Figure 2As shown, the MoO3 sample, compared with the corresponding PDF card 12-0517, belongs to the P4 / nmm(129) space group, with lattice constants a=45.990 Å, b=45.990 Å, c=3.937 Å, belonging to a tetragonal crystal structure. It can be seen that the diffraction of the MoO3 sample is consistent, and the diffraction peak intensity of the obtained product is high, indicating that the sample has high crystallinity. The diffraction peaks of the synthesized product molybdenum disulfide at 2θ of 26.0°, 37.0° and 53.6° after sulfidation treatment correspond to the (004), (102) and (105) crystal planes of MoS2, respectively, which correspond one-to-one with PDF card 37-1492, with lattice constants a=3.161 Å, b=3.161 Å, c=12.299 Å. MoS2 belongs to the P63 / mmc(194) space group, and the surface synthesized is a hexagonal structure of MoS2.

[0034] To analyze the size, microstructure, and distribution of the samples, we performed scanning electron microscopy (SEM) characterization on the MoS2 products. The SEM images are shown below. Figure 3 As shown, (a) and (b) are scanning electron microscope images with scale bars of 5 μm and 1 μm, respectively. It can be seen that the overall particle size of MoS2 is relatively large, and there are obvious densely packed small pores in the structure. This indicates that a porous structure of MoO3 was successfully prepared by the ice crystal template method. The MoS2 prepared after sulfidation using this as a template is multi-layered and plate-like, with abundant pores and a relatively uniform morphology. This multi-layered structure can increase the specific surface area of ​​the sample, increase the number of active sites, and give it good adsorption capacity. At high magnification, it can be found that the morphology of molybdenum disulfide is a perforated structure with a large number of small pores inside, and the layers are stacked. Through analysis and comparison with the standard card 37-1492, the results show that it has crystal planes such as (004), (102), and (105), and the diffraction peak intensity is high, indicating that the obtained molybdenum disulfide is a hexagonal structure with high crystallinity. The product is pure phase molybdenum disulfide.

[0035] To better understand the morphology and structure of molybdenum disulfide, we performed transmission electron microscopy characterization. Figure 4 The images are TEM images of MoS2. (a) and (b) are TEM images with scale bars of 500 nm and 50 nm, respectively. It can be seen that the synthesized MoS2 contains a large number of uniform small pore structures. In addition, abundant hierarchical micropores are uniformly dispersed in the pores. MoS2 also presents a plate-like structure with layers stacked together. The TEM results strongly prove that the crystallinity of the synthesized molybdenum disulfide is excellent, which is consistent with the XRD results.

[0036] Comparative Example 1 Citric acid was replaced with sucrose with an equimolar carbon content, and the remaining steps and parameters were the same as in Example 1.

[0037] Comparative Example 2 Compared with Example 1, no ammonia was added when preparing the precursor solution, and the remaining steps were the same as in Example 1.

[0038] Comparative Example 3 Compared to Example 1, the difference lies in the calcination treatment during the preparation of MoO3, which is as follows: The precursor was calcined at 300 °C for 2 h. The calcined precursor was then added to deionized water and centrifuged at 5500 rpm. The solid components were collected, and the process was repeated twice with the addition of water. The collected solid components were then dried at 60 °C for 5 h to obtain MoO3. This process involved only one calcination step.

[0039] Figure 5 These are scanning electron microscope (SEM) images of MoS2 prepared in the above comparative examples. Comparative Example 1 is shown below. Figure 5 As shown in (a) and (b), where the scale bar in (a) is 5 μm and the scale bar in (b) is 1 μm, the introduction of sucrose led to a significant change in the viscosity, surface tension, and pH of the precursor solution. This resulted in alterations in the growth, sublimation kinetics, and thermodynamics of the components in the precursor solution. Furthermore, sucrose in this system only served as a carbon source framework and could not participate in pH adjustment or act as a chelating agent. Consequently, the final MoO3 exhibited significant agglomeration, which was detrimental to the subsequent preparation of MoS2. In contrast, Comparative Example 2 did not include ammonia, as shown in... Figure 5 As shown in (c) and (d), where the scale bar for (c) is 5 μm and for (d) is 1 μm, it can be observed that large blocky structures and obvious aggregation still exist in the samples. This is because no ammonia was added to the precursor solution, and the citric acid and Mo in the system... 6+ The chelation between the two components was weak, and the pH of the precursor solution also changed significantly, leading to agglomeration during the template preparation process. Furthermore, the reaction was hindered at low temperatures, ultimately preventing the formation of a porous structure in the MoS2 prepared using this template. In Comparative Example 3, a one-step calcination method was used to prepare the MoO3 template. However, the rapid decomposition during the citric acid calcination process caused pore collapse in the generated MoO3, resulting in low porosity and an unsatisfactory specific surface area. Consequently, the prepared MoS2 also failed to form a superior porous structure. Specifically, as shown below... Figure 5 As shown in (e) and (f), the scale bar of (e) is 5 μm and the scale bar of (f) is 1 μm.

[0040] The essence of electrocatalytic reactions lies in the adsorption, activation, reaction, and desorption of reactants at the active sites of the catalyst. To a certain extent, a larger BET specific surface area can increase the density of active sites and optimize their accessibility, which is one of the core foundations for improving catalytic activity. By testing the specific surface area (BET) of the samples in Example 1 and various comparative examples, as... Figure 7 As shown, the specific surface area of ​​Example 1 is 128.02 m². 2 / g, compared to Comparative Example 1 (22.19m 2 / g), Comparative Example 2 (18.20m 2 / g) and Comparative Example 3 (21.86m 2 / g) manifests as a larger specific surface area.

[0041] In the field of electrocatalysis, the onset voltage refers to the minimum applied voltage required for an electrocatalytic reaction (hydrogen evolution) to reach a specific target current. A low onset voltage in an electrocatalyst is essentially a direct reflection of its excellent catalytic performance. A low onset voltage is a core indicator of an electrocatalyst's superior activity, high kinetic efficiency, and high application value. For example... Figure 8 As shown in the figure, it can be seen from the LSV curve that at 10 mA / cm 2 At the specified current density, Example 1 (122.2 mV) exhibited a lower start-up voltage compared to Comparative Example 1 (254.1 mV), Comparative Example 2 (264.0 mV), and Comparative Example 3 (286.2 mV). This indicates that MoS2 prepared by using MoO3, which was prepared by preparing a precursor from ammonia, citric acid, and sodium chloride and then calcining it in stages, as a template has superior catalytic performance.

[0042] Example 2 A method for preparing molybdenum disulfide nanomaterials based on the ice crystal template method includes the following steps: Step (I) Preparation of MoO3 (1) Preparation of precursor solution Ammonium molybdate was added to deionized water and dissolved. Ammonia was then added and mixed thoroughly. After the solution became clear, citric acid and sodium chloride were added sequentially and ultrasonically mixed thoroughly to prepare a precursor solution. The ratio of the amount of ammonium molybdate, citric acid, sodium chloride, and deionized water was 1 g: 1.2 g: 4 g: 20 mL, the volume ratio of deionized water to ammonia was 2:0.1, and the mass concentration of ammonia was 25%. (2) Freeze-drying treatment The precursor solution was placed in an aluminum can, and the aluminum can was placed in liquid nitrogen and frozen for 5 min. After the precursor solution was frozen to a solid state, it was freeze-dried at -55 ℃ and 25 Pa for 40 h to obtain the precursor. (3) Calcination, washing and drying treatment The precursor was first calcined at 220℃ for 40 min, and then calcined at 280℃ for 2 h. The calcined precursor was added to deionized water and centrifuged at 6000 rpm. The solid components were collected, and water was added again and the centrifugation was repeated 3 times. The solid components were then collected and dried at 60℃ for 4 h to obtain MoO3. Step (II) Preparation of MoS2 The MoO3 and thiourea prepared in step (I) were added to a mixed solvent consisting of deionized water and ethanol. After mixing evenly, a sulfidation reaction was carried out, specifically at 170°C for 2.5 h. The ratio of MoO3, thiourea and the mixed solvent was 0.15 g: 0.08 g: 30 mL, and the volume ratio of deionized water and ethanol in the mixed solvent was 1:2. After the reaction was completed, the solid components were collected and dried at 60°C to obtain MoS2 nanomaterials.

[0043] The preparation in this embodiment is as follows Figure 6 As shown in (a) and (b), where the scale bar in (a) is 5 μm and the scale bar in (b) is 1 μm, the specific surface area of ​​the prepared MoS2 is 123.36 m². 2 / g, at 10mA / cm 2 The starting voltage at current density is 147.0mV.

[0044] Example 3 A method for preparing molybdenum disulfide nanomaterials based on the ice crystal template method includes the following steps: Step (I) Preparation of MoO3 (1) Preparation of precursor solution Ammonium molybdate was added to deionized water and dissolved. Ammonia was then added and mixed thoroughly. After the solution became clear, citric acid and sodium chloride were added sequentially and ultrasonically mixed to prepare a precursor solution. The ratio of the amount of ammonium molybdate, citric acid, sodium chloride, and deionized water was 1 g:1.5 g:5 g:20 mL, the volume ratio of deionized water to ammonia was 2:0.2, and the mass concentration of ammonia was 25%. (2) Freeze-drying treatment The precursor liquid was placed in an aluminum can, and the aluminum can was placed in liquid nitrogen and frozen for 8 min. After the precursor liquid was frozen to solid, it was freeze-dried at -45 ℃ and 15 Pa for 44 h to obtain the precursor. (3) Calcination, washing and drying treatment The precursor was first calcined at 250℃ for 30 min, and then calcined at 310℃ for 1.5 h. The calcined precursor was added to deionized water and centrifuged at 5000 rpm. The solid components were collected, and water was added again and the centrifugation was repeated twice. The solid components were then collected and dried at 60℃ for 5 h to obtain MoO3. Step (II) Preparation of MoS2 The MoO3 and thiourea prepared in step (I) were added to a mixed solvent consisting of deionized water and ethanol. After mixing evenly, a sulfidation reaction was carried out, specifically at 190°C for 1.5 h. The ratio of MoO3, thiourea and the mixed solvent was 0.14 g: 0.07 g: 30 mL, and the volume ratio of deionized water and ethanol in the mixed solvent was 1:2. After the reaction was completed, the solid components were collected and dried at 60°C to obtain MoS2 nanomaterials.

[0045] The preparation in this embodiment is as follows Figure 6 As shown in (c) and (d), where the scale bar for (c) is 5 μm and the scale bar for (d) is 1 μm, the specific surface area of ​​MoS2 prepared in this embodiment is 127.58 m². 2 / g, at 10mA / cm 2 The starting voltage at current density is 147.0 mV.

Claims

1. A method for preparing porous molybdenum disulfide based on the ice crystal template method, characterized in that: MoO3 is prepared using the ice crystal template method. Then, MoS2 is obtained by using MoO3 as the molybdenum source, thiourea as the pure sulfur source, and a mixture of deionized water and ethanol as the mixed solvent through a sulfidation reaction. Specifically, the ice crystal template method involves adding ammonium molybdate and ammonia water to deionized water in sequence, mixing them evenly, and then adding citric acid and sodium chloride in sequence to prepare a precursor solution. The precursor solution is then freeze-dried to obtain a precursor, which is then calcined and washed and dried to obtain MoO3.

2. The method for preparing porous molybdenum disulfide based on the ice crystal template method as described in claim 1, characterized in that: The ratio of ammonium molybdate, citric acid, sodium chloride, and deionized water in the precursor solution is 1 g: 1.3~1.5 g: 4~5 g: 20 mL, the volume ratio of deionized water to ammonia is 10: 0.1~0.2, and the mass concentration of ammonia is 25~28%.

3. A method for preparing porous molybdenum disulfide based on the ice crystal template method as described in claim 1 or 2, characterized in that: The calcination process involves first calcining the freeze-dried precursor at 220-250°C for 30-40 minutes, and then calcining it at 280-310°C for 1.5-2 hours.

4. A method for preparing porous molybdenum disulfide based on the ice crystal template method as described in any one of claims 1-3, characterized in that: The freeze-drying process involves placing the precursor liquid in liquid nitrogen for 5-8 minutes to freeze it into a solid state, and then freeze-drying it at -45 to -55°C and 15 to 25 Pa for 40 to 48 hours to obtain the precursor.

5. A method for preparing porous molybdenum disulfide based on the ice crystal template method as described in any one of claims 1-4, characterized in that: In the sulfidation reaction, the ratio of MoO3, thiourea, and mixed solvent is 0.14~0.15 g: 0.07~0.08 g: 30 mL, and the volume ratio of deionized water and ethanol in the mixed solvent is 1:

2.

6. The method for preparing porous molybdenum disulfide based on the ice crystal template method as described in claim 5, characterized in that: The vulcanization reaction is carried out at a temperature of 170-190 °C for 20-24 h.

7. A method for preparing porous molybdenum disulfide based on the ice crystal template method, characterized in that, Includes the following steps: Step (I) Preparation of MoO3 (1) Preparation of precursor solution Ammonium molybdate is added to deionized water and dissolved. Ammonia is then added and mixed thoroughly. After the solution becomes clear, citric acid and sodium chloride are added sequentially and ultrasonically mixed until homogeneous to prepare a precursor solution. The ratio of the amount of ammonium molybdate, citric acid, and sodium chloride to deionized water is 1 g: 1.3~1.5 g: 4~5 g: 20 mL, the volume ratio of deionized water to ammonia is 2:0.1~0.2, and the mass concentration of ammonia is 25~28%. (2) Freeze-drying treatment The precursor solution was placed in an aluminum can, and the aluminum can was placed in liquid nitrogen and frozen for 5-8 min. After the precursor solution was frozen to a solid state, it was freeze-dried at -45 to -55 °C and 15 to 25 Pa for 40 to 48 h to obtain the precursor. (3) Calcination, washing and drying treatment The precursor was first calcined at 220-250℃ for 30-40 min, and then calcined at 280-310℃ for 1.5-2 h. The calcined precursor was added to deionized water and centrifuged at 5000-6000 rpm. The solid components were collected, and water was added again and the centrifugation was repeated 2-3 times. The solid components were then collected and dried at 60℃ for 4-5 h to obtain MoO3. Step (II) Preparation of MoS2 The MoO3 and thiourea prepared in step (I) were added to a mixed solvent consisting of deionized water and ethanol. After mixing evenly, a sulfidation reaction was carried out. Specifically, the reaction was carried out at 170~190℃ for 1.5~2.5 h. The ratio of the amount of MoO3, thiourea and mixed solvent was 0.14~0.15g:0.07~0.08g:30mL. The volume ratio of deionized water and ethanol in the mixed solvent was 1:

2. After the reaction was completed, the solid components were collected and dried at 60℃ to obtain MoS2 nanomaterials.

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