Mesoporous nanodisc-like tungsten trioxide and preparation method and application thereof

Abstract

The present application relates to a kind of mesoporous nanodisc-shaped tungsten trioxide and its preparation method and application, by controlling the matching of surfactant and tungsten salt and its reaction activity in water oil interface, the crosslinking and aggregation between micelles in hydrothermal reaction process are regulated, the gap inside micelle is precisely tailored, and the nanodisc-shaped tungsten trioxide powder with abundant mesoporous channel can be prepared controllably.The mesoporous nanodisc-shaped tungsten trioxide powder prepared has high structured pore network structure, with large specific surface area, which is beneficial to the reaction contact between hydrogen and catalyst, improves reaction efficiency;As electrocatalyst, it shows significant auxiliary energy-saving hydrogen production activity while purifying urea wastewater, and has very broad application prospect in the field of urea auxiliary energy-saving hydrogen production.

Description

Technical Field

[0001] This invention relates to the field of inorganic nanomaterials technology, specifically to a mesoporous nanodisc-shaped tungsten trioxide, its preparation method, and its applications. Background Technology

[0002] Hydrogen gas has an excellent energy density (~282 kJ / mol). -1 Hydrogen, with its pollution-free, zero-carbon properties and outstanding recyclability, is widely recognized as a promising core energy carrier. Electrochemical water electrolysis is an efficient and economical sustainable hydrogen production strategy. However, the inherently slow kinetics of the oxygen evolution reaction (OER) lead to excessive energy consumption and high H2 costs, severely hindering overall water separation efficiency. The urea oxidation reaction (UOR) requires only 0.37V of thermodynamic potential, significantly lower than the OER (1.23V), saving up to 70% of energy. Furthermore, urea electrolysis can simultaneously provide a green electrochemical method for remediating urea-rich wastewater from industrial synthesis and sanitary wastewater. However, urea electrolysis is still subject to complex 6e- transfer processes, complex gas (CO2 and N2) evolution, and inherently slow kinetics. Therefore, developing low-cost, highly active UOR electrocatalysts is crucial for the widespread commercialization of this promising energy conversion technology.

[0003] Tungsten trioxide (TDC) is abundant and highly stable, making it a good catalyst for urea-assisted water electrolysis to produce hydrogen. However, its poor conductivity and limited active sites severely inhibit hydrogen evolution catalysis. Constructing a mesoporous structure can expose more active sites, improve gas-liquid transport, and increase the contact area between the electrolyte and active sites, thereby enhancing the catalyst's activity and stability. Chinese patent (CN111514911B) uses a solvothermal, thermal decomposition, and in-situ phosphating reduction method to prepare mesoporous carbon-doped WP nanosheets using a WO3 / amine hybrid precursor. This nanosheet electrocatalyst exhibits a current density of 10 mA cm⁻¹ in an acidic electrolyte. -2 The overpotential at that time was 190mV, and the Tafel slope was 108mV dec. -1 The literature (Adv. Energy Mater. 2022, 12, 2200067.) easily prepared a self-supporting mesoporous heterostructure Fe2O3 / CuO on a nickel framework using lattice adaptation. Based on the high-speed transport characteristics of the nanoporous structure, Fe2O3 / CuO exhibited high oxygen evolution reaction catalytic activity in 1.0 M KOH at a current density of 10 mA cm⁻¹. -2 The overpotential at that time was approximately 0.22V, and it had a low Tafel slope (44.5mV dec). -1 ); at a current density of 100 mA cm -2At this time, the overpotential is as low as 0.26V, and the alkaline electrolyzer assembled with bifunctional Fe2O3 / CuO catalyst exhibits a low overall water splitting voltage (1.49V@10mA cm⁻¹). -2 It is superior to noble metal-based catalysts.

[0004] The above methods provide a framework for the preparation of energy-saving hydrogen production materials assisted by urea wastewater, but some problems still need to be solved: 1) Mesoporous materials, due to their highly ordered pore structure, have a large specific surface area, which is beneficial for applications such as adsorption, catalysis, and energy storage. However, the controllable synthesis of tungsten-based materials with abundant mesoporous channels remains extremely challenging; 2) Currently reported electrocatalysts have limited performance at 100 mA cm⁻¹. -2 It can operate continuously for 200 hours at current density without showing significant performance degradation, but its long-term stability under high operating current in urea-assisted water electrolysis hydrogen production systems remains challenging. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a mesoporous nanodisc-shaped tungsten trioxide, its preparation method, and its applications.

[0006] To achieve the above objectives, this invention discloses a method for preparing mesoporous nanodisc-shaped tungsten trioxide, comprising the following steps:

[0007] (1) Prepare a soluble tungsten salt solution using water as a solvent; prepare a cationic surfactant solution using undecyl alcohol as a solvent; under stirring conditions, add the above soluble tungsten salt solution dropwise to the cationic surfactant solution to obtain mixed solution A;

[0008] Furthermore, in step (1), the volume ratio of water to undecyl alcohol is less than 1:1.

[0009] Furthermore, in step (1), the soluble tungsten salt is one or more of ammonium tungstate, ammonium metatungstate, and sodium tungstate, and the concentration of the soluble tungsten salt solution is 25-35 mmol / L.

[0010] Furthermore, in step (1), the cationic surfactant is dodecyltrimethylammonium chloride, and the concentration of the cationic surfactant solution is 20-30 mmol / L.

[0011] Furthermore, the stirring rate in step (1) is 60-150 r / min, and the stirring time is 1.5-3.5 h.

[0012] (2) Under stirring conditions, the acid solution is added dropwise to the mixed solution A to obtain the mixed solution B;

[0013] Furthermore, the acid solution in step (2) is acetic acid, with a concentration of 0.4-1.5 mol / L, a volume of 6-10 mL, a stirring rate of 70-230 r / min, and a stirring time of 2-6 h.

[0014] (3) The mixed solution B was subjected to a hydrothermal reaction. After the reaction was completed, the solution was filtered, washed and dried to finally obtain mesoporous nanodisc tungsten trioxide powder.

[0015] Furthermore, the hydrothermal reaction described in step (3) is a staged reaction. First, the temperature is raised from room temperature to the first stage reaction temperature and reacted at the first stage reaction temperature for a period of time. Then, the temperature is raised from the first stage reaction temperature to the second stage reaction temperature and reacted at the second stage reaction temperature for a period of time.

[0016] Furthermore, in step (3), the heating rate from room temperature to the first stage reaction temperature is 0.5-5℃ / min, the first stage reaction temperature is 90-120℃, and the reaction time is 5-9h; the heating rate from the first stage reaction temperature to the second stage reaction temperature is 5-15℃ / min, the second stage reaction temperature is 130-170℃, and the reaction time is 4-10h.

[0017] Furthermore, in step (3), the drying temperature is 60-85℃ and the drying time is 8-13h.

[0018] The present invention also aims to provide a mesoporous tungsten trioxide nanodisc powder prepared according to the above method and its application in urea wastewater-assisted hydrogen production.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) This invention regulates the interfacial reactivity of the water-oil two-phase solution by controlling the volume ratio of the two phases, and modifies the surface of tungsten salt with a cationic surfactant. By controlling the concentration of the soluble tungsten salt aqueous solution, a mesoporous nanodisc-shaped tungsten trioxide powder can be prepared. The formation of this mesoporous structure is due to the intermolecular interaction of surfactant molecules. When the soluble tungsten salt solution is added dropwise to the cationic surfactant solution, the tungstate ions in the tungsten salt are surrounded by the hydrophilic head groups of the surfactant molecules, forming a surfactant ion-tungstate (RN) structure. + -WO4 2- The micelle structure of ion pairs. As the hydrothermal reaction proceeds, cross-linking and aggregation occur between micelles due to electrostatic and hydrophobic interactions. The precise trimming of the internal voids of the micelles results in the retention of these voids, forming a mesoporous structure. This allows for the controlled preparation of nanodisc-shaped tungsten trioxide powder with abundant mesoporous channels.

[0021] (2) The prepared mesoporous nanodisc-shaped tungsten trioxide powder has abundant mesoporous channels, exhibiting significantly enhanced mesoscopic mass transfer characteristics and a large specific surface area, which is beneficial for the reaction contact between hydrogen and the catalyst, thus improving the reaction efficiency. This mesoporous nanodisc-shaped tungsten trioxide powder, as an electrocatalyst, exhibits significant auxiliary energy-saving hydrogen production activity while purifying urea wastewater: compared with the conventional water electrolysis system composed of hydrogen evolution reaction and oxygen evolution reaction, the urea-assisted water electrolysis hydrogen production system reaches 100 mA cm⁻¹. -2 The voltage required for the current density was reduced by 329mV, and at 100mA cm -2 The retention rate after 240 hours of operation at high current density is 90.55%, which shows great promise for application in the field of urea-assisted energy-saving hydrogen production. Attached Figure Description

[0022] Figure 1 X-ray diffraction (XRD) images of the mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1 and the rod-shaped tungsten trioxide powder prepared in Comparative Example 1.

[0023] Figure 2 Field emission scanning electron microscope (FESEM) image of the mesoporous nanodisc tungsten trioxide powder prepared in Example 1;

[0024] Figure 3 Field emission scanning electron microscope (FESEM) image of the mesoporous nanodisc tungsten trioxide powder prepared in Example 2;

[0025] Figure 4 This is a field emission scanning electron microscope (FESEM) image of the mesoporous nanodisc tungsten trioxide powder prepared in Example 3;

[0026] Figure 5 A field emission scanning electron microscope (FESEM) image of the rod-shaped tungsten trioxide powder prepared in Comparative Example 1;

[0027] Figure 6 The mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1 was subjected to a concentration of 1 mol·L⁻¹. -1 Two-electrode LSV curves in KOH + 0.5 molurea electrolyte and H2O;

[0028] Figure 7 The mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1 and the rod-shaped tungsten trioxide powder prepared in Comparative Example 1 were respectively subjected to a concentration of 1 mol·L⁻¹. -1 Two-electrode LSV curves of KOH + 0.5 mol urea electrolyte;

[0029] Figure 8The mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1 was tested in the HER||UOR system at 100 mA·cm⁻¹. -2 Timing current curves at current density;

[0030] Figure 9 The image shows a comparison of the stability of the mesoporous nanodisc tungsten trioxide powder prepared in Example 1 as an electrocatalyst and the electrocatalysts currently reported as used in a two-electrode urea-assisted hydrogen evolution process. Detailed Implementation

[0031] To better understand the content of this invention, specific embodiments will be used to further illustrate the invention below. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps; however, the scope of protection of this invention is not limited to the following embodiments.

[0032] Example 1:

[0033] (1) Prepare a sodium tungstate solution with a concentration of 25 mmol / L using 100 mL of water as solvent; prepare a dodecyltrimethylammonium chloride solution with a concentration of 20 mmol / L using 300 mL of undecyl alcohol as solvent; add the sodium tungstate solution dropwise to the dodecyltrimethylammonium chloride solution under stirring conditions to obtain mixed solution A; wherein, the stirring rate is 100 r / min and the stirring time is 2 h;

[0034] (2) Under stirring conditions, 8 mL of 1 mol / L acetic acid was added dropwise to mixed solution A to obtain mixed solution B; wherein, the stirring rate was 100 r / min and the stirring time was 2 h;

[0035] (3) The mixed solution B was subjected to a hydrothermal reaction. The hydrothermal reaction was a staged reaction. First, the temperature was increased from room temperature to 110℃ at a heating rate of 2℃ / min and reacted at 110℃ for 6 hours. Then, the temperature was increased from 110℃ to 150℃ at a heating rate of 8℃ / min and reacted at 150℃ for 8 hours. After the reaction was completed, the solution was filtered, washed, and dried at 60℃ for 12 hours to finally obtain mesoporous nanodisc tungsten trioxide powder.

[0036] Example 2:

[0037] (1) Prepare a sodium tungstate solution with a concentration of 27 mmol / L using 100 mL of water as a solvent; prepare a dodecyltrimethylammonium chloride solution with a concentration of 23 mmol / L using 300 mL of undecyl alcohol as a solvent; under stirring conditions, add the above sodium tungstate solution dropwise to the dodecyltrimethylammonium chloride solution to obtain mixed solution A; wherein, the stirring rate is 100 r / min and the stirring time is 2 h;

[0038] (2) Under stirring conditions, 8 mL of 1 mol / L acetic acid was added dropwise to mixed solution A to obtain mixed solution B; wherein, the stirring rate was 100 r / min and the stirring time was 2 h;

[0039] (3) The mixed solution B was subjected to a hydrothermal reaction. The hydrothermal reaction was a staged reaction. First, the temperature was increased from room temperature to 110℃ at a heating rate of 2℃ / min and reacted at 110℃ for 6 hours. Then, the temperature was increased from 110℃ to 150℃ at a heating rate of 8℃ / min and reacted at 150℃ for 8 hours. After the reaction was completed, the solution was filtered, washed, and dried at 60℃ for 12 hours to finally obtain mesoporous nanodisc tungsten trioxide powder.

[0040] Example 3:

[0041] (1) Prepare a sodium tungstate solution with a concentration of 30 mmol / L using 100 mL of water as a solvent; prepare a dodecyltrimethylammonium chloride solution with a concentration of 26 mmol / L using 300 mL of undecyl alcohol as a solvent; under stirring conditions, add the above sodium tungstate solution dropwise to the dodecyltrimethylammonium chloride solution to obtain mixed solution A; wherein, the stirring rate is 100 r / min and the stirring time is 2 h;

[0042] (2) Under stirring conditions, 8 mL of 1 mol / L acetic acid was added dropwise to mixed solution A to obtain mixed solution B; wherein, the stirring rate was 100 r / min and the stirring time was 2 h;

[0043] (3) The mixed solution B was subjected to a hydrothermal reaction. The hydrothermal reaction was a staged reaction. First, the temperature was increased from room temperature to 110℃ at a heating rate of 2℃ / min and reacted at 110℃ for 6 hours. Then, the temperature was increased from 110℃ to 150℃ at a heating rate of 8℃ / min and reacted at 150℃ for 8 hours. After the reaction was completed, the solution was filtered, washed, and dried at 60℃ for 12 hours to finally obtain mesoporous nanodisc tungsten trioxide powder.

[0044] Comparative Example 1:

[0045] (1) Under stirring conditions, 2 mL of 1 mol / L nitric acid was added dropwise to 10 mL of 10 mol / L hydrogen peroxide, and 3 mmol of sodium tungstate powder was added at the same time to obtain mixed solution A; wherein, the stirring rate was 90 r / min and the stirring time was 2 h;

[0046] (2) The mixed solution A was subjected to a hydrothermal reaction. The temperature was increased from room temperature to 180℃ at a rate of 5℃ / min, and the reaction was carried out at 180℃ for 6 hours. After the reaction was completed, the solution was filtered, washed, and vacuum dried at 60℃ for 12 hours to finally obtain rod-shaped tungsten trioxide powder.

[0047] Figure 1 X-ray diffraction (XRD) images of the mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1 and the rod-shaped tungsten trioxide powder prepared in Comparative Example 1, from... Figure 1 It can be seen that the peak position in the XRD pattern of the mesoporous nanodisc tungsten trioxide powder is at the position of WO3 (PDF#89-4477), proving that the product prepared in Example 1 is WO3. The peak position in the XRD pattern of the rod-shaped tungsten trioxide powder is at the position of WO3 (PDF#89-4477), proving that the product prepared in Comparative Example 1 is also WO3.

[0048] Figure 2 The image shown is a FESEM image of the mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1. Figure 2 It can be seen that the mesoporous nanodisc tungsten trioxide particles are uniform in size and evenly distributed, and the surface exhibits a mesoporous morphology.

[0049] Figure 3 This is a field emission scanning electron microscope (FESEM) image of the mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 2. Figure 3 It can be seen that the mesoporous nanodisc-shaped tungsten trioxide particles are evenly distributed and the surface exhibits a mesoporous morphology.

[0050] Figure 4 These are field emission scanning electron microscope (FESEM) images of the mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 3. Figure 4 It can be seen that the mesoporous nanodisc-shaped tungsten trioxide particles are evenly distributed and the surface exhibits a mesoporous morphology.

[0051] Figure 5 The image shows a field emission scanning electron microscope (FESEM) image of the rod-shaped tungsten trioxide powder prepared in Comparative Example 1. Figure 5 As can be seen, the product is evenly distributed and exhibits a rod-like structure.

[0052] The electrochemical performance of the mesoporous nanodisc-shaped tungsten trioxide powder obtained in Example 1 as an anode and cathode catalyst was tested using an electrochemical workstation 660E. The results are as follows: Figure 6 , Figure 7 , Figure 8 As shown.

[0053] Figure 6 The mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1 was subjected to a concentration of 1 mol·L⁻¹. -1 Two-electrode LSV curves in KOH + 0.5 molurea electrolyte and H2O. Figure 6Electrochemical performance test results show that, compared with traditional water electrolysis, the urea-assisted water decomposition reaction saves 329 mV of voltage (urea-assisted water decomposition at 100 mA cm⁻¹). -2 The voltage is 1.46V, and water electrolysis occurs at 100mA cm⁻¹. -2 (at 1.789V) to provide 100mA cm -2 The current density.

[0054] The rod-shaped tungsten trioxide powder obtained in Comparative Example 1 was used as both an anode and cathode catalyst in an electrochemical workstation (660E) for electrochemical performance testing. The results are as follows: Figure 7 As shown. Figure 7 The LSV curves of the mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1 and the rod-shaped tungsten trioxide powder prepared in Comparative Example 1 are shown in the two-electrode LSV curves of 1 mol·L⁻¹ KOH + 0.5 mol Urea electrolyte. Figure 7 Electrochemical performance test results show that: at 1 mol·L -1 In a KOH + 0.5 mol Urea electrolyte, a rod-shaped tungsten trioxide electrocatalyst requires a voltage of 1.54 V to provide a 100 mA cm⁻¹. -2 The current density is higher than that of the mesoporous nanodisc tungsten trioxide electrocatalyst at the same current density (1.46V).

[0055] Figure 8 The mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1 was tested in the HER||UOR system at 100 mA·cm⁻¹. -2 Chronocurrent curves at current density, showing the mesoporous nanodisc tungsten trioxide powder as an anode and cathode catalyst at 100 mA cm⁻¹. -2 The stability at current density showed that the retention rate after 240 hours of stabilization was 90.55%.

[0056] Figure 9 The mesoporous nanodisc-shaped tungsten trioxide powder prepared in Example 1 was used as an electrocatalyst, and the electrocatalysts currently reported were used at 100 mA cm⁻¹. -2The stability comparison of urea-assisted hydrogen evolution at a current density of 100 mA is shown in the figure: A corresponds to Example 1, with a stabilization time of 240 h; B corresponds to Chem. Eng. J, 2023, 471:144657, with a stabilization time of 200 h; C corresponds to Small, 2023, 2304390, with a stabilization time of 100 h; D corresponds to Small, 2023, 19:2302923, with a stabilization time of 60 h; E corresponds to Adv. Funct. Mater, 2023, 33:2212811, with a stabilization time of 60 h; and F corresponds to Small, 2023, 19:2302698, with a stabilization time of 20 h. The results indicate that using mesoporous nanodisc-shaped tungsten trioxide powder as both cathode and anode electrocatalysts at 100 mA cm⁻¹ is effective. -2 At a current density, its stability as a two-electrode urea-assisted hydrogen evolution catalyst is superior to the five electrocatalysts currently reported.

[0057] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing mesoporous nanodisc-shaped tungsten trioxide, characterized in that, Specifically, the following steps are included: (1) Prepare a soluble tungsten salt solution with water as solvent, the concentration of which is 25-35 mmol / L; prepare a cationic surfactant solution with undecyl alcohol as solvent, the concentration of which is 20-30 mmol / L, wherein the cationic surfactant is dodecyltrimethylammonium chloride, and the volume ratio of water to undecyl alcohol is less than 1:1; under stirring conditions, add the above soluble tungsten salt solution dropwise to the cationic surfactant solution to obtain mixed solution A; (2) Under stirring conditions, the acid solution is added dropwise to the mixed solution A to obtain the mixed solution B; (3) The mixed solution B is subjected to a hydrothermal reaction. The hydrothermal reaction is a staged reaction. First, the temperature is raised from room temperature to 90-120℃ at a rate of 0.5-5℃ / min, and the reaction is carried out at 90-120℃ for 5-9 hours. Then, the temperature is raised from 90-120℃ to 130-170℃ at a rate of 5-15℃ / min, and the reaction is carried out at 130-170℃ for 4-10 hours. After the reaction is completed, the solution is filtered, washed, and dried to finally obtain mesoporous nanodisc tungsten trioxide powder.

2. The method for preparing mesoporous nanodisc-shaped tungsten trioxide as described in claim 1, characterized in that: In step (1), the stirring rate is 60-150 r / min and the stirring time is 1.5-3.5h.

3. The method for preparing mesoporous nanodisc-shaped tungsten trioxide as described in claim 1, characterized in that: In step (1), the soluble tungsten salt is one or more of ammonium tungstate, ammonium metatungstate, and sodium tungstate.

4. The method for preparing mesoporous nanodisc-shaped tungsten trioxide as described in claim 1, characterized in that: The acid solution in step (2) is acetic acid, with a concentration of 0.4-1.5 mol / L, a volume of 6-10 mL, a stirring rate of 70-230 r / min, and a stirring time of 2-6 h.

5. The method for preparing mesoporous nanodisc-shaped tungsten trioxide as described in claim 1, characterized in that: In step (3), the drying temperature is 60-85℃ and the drying time is 8-13 h.

6. Mesoporous nanodisc-shaped tungsten trioxide powder prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the mesoporous nanodisc-shaped tungsten trioxide powder as described in claim 6 in hydrogen production assisted by urea wastewater.

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