A bipyramidal tungsten(molybdenum) trioxide powder, a preparation method and application thereof

Abstract

The present application relates to a kind of double-cone tungsten trioxide (molybdenum) powder and its preparation method and application, in preparation process, by controlling the concentration of glycerol and oxalic acid, the viscosity of reaction solution is adjusted, the growth of tungsten trioxide (molybdenum) powder (001) crystal surface and (110) crystal surface is inhibited, and monodisperse double-cone tungsten trioxide (molybdenum) powder with highly exposed (100) crystal surface can be prepared.The powder has higher specific surface area and specific exposed crystal surface, and can realize the rapid detection of trace hydrogen.The double-cone tungsten trioxide (molybdenum) powder prepared by the present application, as a sensitive material, is made into a hydrogen sensor, which shows a high response value (96) to 100 ppb H2 at 100 DEG C, and the response time is 3 s;It has a faster response time at low concentration.The sensor made of the double-cone material is much better than the currently reported hydrogen sensors of the same category, and is expected to promote the application of hydrogen sensor in hydrogenation station and new energy vehicle field.

Description

Technical Field

[0001] This invention relates to the field of inorganic materials technology, specifically to a biconical tungsten trioxide (molybdenum) powder, its preparation method, and its application. Background Technology

[0002] Hydrogen has a high energy density and produces pollution-free byproducts, making it widely used in power generation, chemical industry, food, and medical fields. However, hydrogen is colorless and odorless, easily leaked, and its explosive limits in air are 4-75 vol%. Therefore, developing an effective and practical method for online and real-time trace detection of hydrogen is crucial. Metal-oxide-semiconductor (MOS) sensors are considered ideal candidates for hydrogen monitoring due to their low cost, long lifespan, low power consumption, fast response, and reliable sensitivity. Essentially, MOS sensors utilize the contact and reaction between a sensitive material and gas molecules in the environment, converting the physicochemical changes on the surface of the sensitive material into electrical signals.

[0003] Tungsten oxide (molybdenum) has proven to be one of the most attractive sensing materials due to its structural flexibility, chemical stability, and high oxygen vacancy diffusion coefficient. However, tungsten oxide (molybdenum) as a sensing material for MOS sensors usually has certain disadvantages, such as slow detection response speed, requiring a certain amount of time to respond to changes in the target gas, and weak detection response to low concentration gases. Therefore, noble metal doping or morphology control methods are often used to improve these shortcomings to some extent. Invention patent (CN116375091A) reports the synthesis of needle-like nano-tungsten oxide with controllable morphology by adding a control substance in the dropwise step of the preparation process and controlling the amount added; invention patent (CN116893205A) reports that a MEMS hydrogen sensor made of Au-doped SnO2 nanoparticles has a response value of 94 for 150ppm hydrogen; invention patent (CN116794116A) reports the preparation of a metal oxide thin film hydrogen sensor by combining a traditional semiconductor metal oxide with a mesoporous inorganic-organic hybrid layer, with a response value of 247.06 for 30ppm H2 at 75℃ and a response time of 1000s; when the operating temperature is increased to 125℃, the response value is 112.54 and the response time is 151s.

[0004] The above methods provide insights for the design and fabrication of hydrogen sensors, but two main problems remain: 1) Although tungsten trioxide (molybdenum) sensitive film materials with different morphologies can now be prepared, the controllable construction of semiconductor materials with specific crystal planes remains challenging; 2) Traditional gas sensors exhibit some sensitivity to hydrogen, but their detection limits, sensitivity, and response times still cannot meet the safety requirements for rapid and highly sensitive detection of trace hydrogen. Therefore, it is urgent to develop novel controllable synthesis techniques for gas-sensitive materials and precisely regulate the microstructure of MOS gas-sensitive sensing materials to improve their gas-sensing performance. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a biconical tungsten trioxide (molybdenum) powder, its preparation method, and its applications.

[0006] To achieve the above objectives, this invention discloses a method for preparing biconical tungsten trioxide powder, comprising the following steps:

[0007] (1) A soluble tungsten salt solution was prepared using water as a solvent, and a cationic surfactant solution was prepared using diethyl methanol as a solvent. Under stirring conditions, the soluble tungsten salt solution was added dropwise to the cationic surfactant solution to obtain a mixed solution A.

[0008] Furthermore, the soluble tungsten salt mentioned in step (1) is one or more of ammonium tungstate, sodium tungstate, and potassium tungstate, and the concentration of the soluble tungsten salt solution is 0.12-0.86 mol / L.

[0009] Furthermore, the volume of diethylmethanol in step (1) is 100-400 mL, and the volume ratio of water to diethylmethanol is less than or equal to 1:1.

[0010] Furthermore, in step (1), the cationic surfactant is 1-aminoethyl-2-undecylimidazoline hydrochloride, and the concentration of the cationic surfactant is 8-35 mol / L.

[0011] Furthermore, the stirring conditions in step (1) are specifically a stirring rate of 60-180 r / min and a stirring time of 3-8 h.

[0012] (2) Glycerol solution and oxalic acid solution are added to mixed solution A in sequence to finally obtain mixed solution B. The addition method is to add dropwise under stirring conditions.

[0013] Furthermore, in step (2), the concentration of the glycerol solution is 5-20 mol / L and the volume is 10-100 mL; the concentration of the oxalic acid solution is 0.3-1.7 mol / L and the volume is 1-6 mL; the solvent for both the glycerol solution and the oxalic acid solution is deionized water.

[0014] Furthermore, the specific stirring conditions in step (2) are a stirring time of 2-6 hours and a stirring rate of 50-200 r / min;

[0015] (3) The mixed solution B was subjected to a hydrothermal reaction. After the reaction was completed, the product was filtered, washed and dried to obtain biconical tungsten trioxide powder.

[0016] Furthermore, in step (3), the hydrothermal reaction is a staged reaction. First, the mixed solution B is heated to the first stage reaction temperature at room temperature. The first stage reaction temperature is 120-160℃, and the reaction time is 2-6h. After the first stage reaction is completed, the temperature is raised to the second stage reaction temperature. The second stage reaction temperature is 160-200℃, and the reaction time is 12-24h.

[0017] In step (3), the heating rate of mixed solution B to the first stage reaction temperature is 8-20℃ / min at room temperature, and the heating rate of mixed solution B to the second stage reaction temperature is 0.2-1℃ / min after the first stage reaction is completed.

[0018] Furthermore, in step (3), the drying temperature is 40-80℃ and the drying time is 6-24h.

[0019] The present invention also discloses a method for preparing bipyramidal molybdenum trioxide powder, which is the same as the method for preparing bipyramidal tungsten trioxide powder, except that the soluble tungsten salt solution in step (1) is replaced with a soluble molybdenum salt solution. The soluble molybdenum salt is one or more of magnesium molybdate, sodium molybdate, and ammonium molybdate. The concentration of the soluble molybdenum salt solution is 0.25-0.95 mol / L. The bipyramidal molybdenum trioxide powder is obtained in step (3).

[0020] The present invention also discloses a bipyramidal tungsten trioxide (molybdenum) powder obtained by the above preparation method, namely bipyramidal tungsten trioxide powder or bipyramidal molybdenum trioxide powder, which has a structure with highly exposed (100) crystal planes.

[0021] This invention also discloses the application of a gas sensor prepared using the above-mentioned biconical tungsten trioxide (molybdenum) powder, i.e., biconical tungsten trioxide powder or biconical molybdenum trioxide powder as the sensitive material, in the trace detection of H2. At an H2 concentration of 100 ppb, the response value can reach 96 and the response time is 3s. This gas sensor can be used as a high-performance hydrogen sensor for rapid detection of trace hydrogen.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) This invention provides a synthesis technique for preparing tungsten trioxide (molybdenum) materials. By adjusting the concentrations of glycerol and oxalic acid, the viscosity of the reaction solution is changed, and the growth of the (001) and (110) crystal planes of tungsten trioxide (molybdenum) powder is inhibited. By controlling the amount of oxalic acid added, monodisperse bipyramidal tungsten trioxide (molybdenum) powder with highly exposed (100) crystal planes can be prepared. Compared with spherical and plate-like tungsten trioxide (molybdenum) powder, the bipyramidal structure has a higher specific surface area and better chemical reactivity.

[0024] (2) The highly exposed (100) crystal-faceted bipyramidal tungsten trioxide (molybdenum) powder prepared in this invention was used as a sensitive material to fabricate a hydrogen sensor. It exhibited a high response value (96) to 100 ppb H2 at 100℃ with a response time of 3 s; it also showed a relatively fast response time at low concentrations. The sensor made from this bipyramidal material is far superior to currently reported hydrogen sensors of the same type and is expected to promote the application of hydrogen sensors in hydrogen refueling stations and new energy vehicles. Attached Figure Description

[0025] Figure 1 The images shown are SEM images of the bipyramidal tungsten trioxide powder prepared in Example 1, where Figure (a) is a low-magnification morphology image and Figure (b) is a high-magnification morphology image.

[0026] Figure 2 The images shown are TEM images of the biconical tungsten trioxide powder prepared in Example 2, where Figure (a) is a low-resolution image and Figure (b) is a high-resolution image.

[0027] Figure 3 The image shows the XRD pattern of the biconical tungsten trioxide powder prepared in Example 2.

[0028] Figure 4 The response values ​​of the biconical tungsten trioxide powder prepared in Example 3 at different temperatures;

[0029] Figure 5 The values ​​represent the response values ​​of the biconical tungsten trioxide powder prepared in Example 3 at different concentrations.

[0030] Figure 6 The response recovery curve of the biconical tungsten trioxide powder prepared in Example 3;

[0031] Figure 7 This is a comparison chart of hydrogen detection values ​​at low concentrations for the biconical tungsten trioxide powder prepared in Example 3 and other substances disclosed in different literature. Detailed Implementation

[0032] 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.

[0033] Example 1:

[0034] (1) Prepare an ammonium tungstate solution with a concentration of 0.25 mol / L using 80 mL of water as the solvent, and prepare a 10 mol / L 1-aminoethyl-2-undecylimidazoline hydrochloride solution using 240 mL of diethylmethanol as the solvent. Under stirring conditions, add the above ammonium tungstate solution dropwise to the 1-aminoethyl-2-undecylimidazoline hydrochloride solution to obtain mixed solution A; wherein, the stirring rate is 80 r / min and the stirring time is 5 h;

[0035] (2) First, add 20 mL of glycerol solution with a concentration of 14 mol / L to the mixed solution A dropwise under stirring. Then, add 1.5 mL of oxalic acid solution with a concentration of 0.5 mol / L to the above solution dropwise under stirring to finally obtain mixed solution B.

[0036] The specific stirring conditions are a stirring rate of 120 r / min and a stirring time of 6 h;

[0037] (3) The mixed solution B was subjected to a hydrothermal reaction. Specifically, the mixed solution B was first heated to 150°C at room temperature at a heating rate of 8°C / min and reacted at this temperature for 4 hours. Then, the temperature was increased from 150°C to 190°C at a heating rate of 0.5°C / min and reacted at this temperature for 20 hours. After the reaction was completed, the reaction product was filtered, washed, and dried at 40°C for 18 hours to obtain biconical tungsten trioxide powder.

[0038] Example 2:

[0039] (1) Prepare a sodium tungstate solution with a concentration of 0.5 mol / L using 85 mL of water as the solvent, and prepare a 12 mol / L 1-aminoethyl-2-undecylimidazoline hydrochloride solution using 255 mL of diethylmethanol as the solvent. Under stirring conditions, add the above sodium tungstate solution dropwise to the 1-aminoethyl-2-undecylimidazoline hydrochloride solution to obtain mixed solution A; wherein, the stirring rate is 100 r / min and the stirring time is 4 h;

[0040] (2) First, add 12 mL of 18 mol / L glycerol solution dropwise to mixed solution A under stirring. Then, add 2 mL of 0.5 mol / L oxalic acid solution dropwise to the above solution under stirring to finally obtain mixed solution B.

[0041] The specific stirring conditions are a stirring rate of 160 r / min and a stirring time of 3 h;

[0042] (3) The mixed solution B was subjected to a hydrothermal reaction. Specifically, the mixed solution B was first heated to 120°C at room temperature at a heating rate of 10°C / min and reacted at this temperature for 3 hours. Then, the temperature was increased from 120°C to 200°C at a heating rate of 1°C / min and reacted at this temperature for 24 hours. After the reaction was completed, the reaction product was filtered, washed, and dried at 50°C for 20 hours to obtain biconical tungsten trioxide powder.

[0043] Example 3:

[0044] (1) Prepare a potassium tungstate solution with a concentration of 0.6 mol / L using 100 mL of water as the solvent, and prepare a 1-aminoethyl-2-undecylimidazoline hydrochloride solution with a concentration of 20 mol / L using 300 mL of diethylmethanol as the solvent. Under stirring conditions, add the above potassium tungstate solution dropwise to the 1-aminoethyl-2-undecylimidazoline hydrochloride solution to obtain mixed solution A; wherein, the stirring rate is 70 r / min and the stirring time is 8 h;

[0045] (2) First, add 50 mL of 10 mol / L glycerol solution dropwise to mixed solution A under stirring. Then, add 3.5 mL of 0.6 mol / L oxalic acid solution dropwise to the above solution under stirring to finally obtain mixed solution B.

[0046] The specific stirring conditions are a stirring rate of 180 r / min and a stirring time of 2 h;

[0047] (3) The mixed solution B was subjected to a hydrothermal reaction. Specifically, the mixed solution B was first heated to 130°C at room temperature at a heating rate of 15°C / min and reacted at this temperature for 5 hours. Then, the temperature was increased from 130°C to 200°C at a heating rate of 0.8°C / min and reacted at this temperature for 21 hours. After the reaction was completed, the reaction product was filtered, washed, and dried at 80°C for 8 hours to obtain biconical tungsten trioxide powder.

[0048] Example 4:

[0049] (1) Prepare a magnesium molybdate solution with a concentration of 0.85 mol / L using 90 mL of water as the solvent, and prepare a 1-aminoethyl-2-undecylimidazoline hydrochloride solution with a concentration of 32 mol / L using 270 mL of diethylmethanol as the solvent. Under stirring conditions, add the above magnesium molybdate solution dropwise to the 1-aminoethyl-2-undecylimidazoline hydrochloride solution to obtain mixed solution A; wherein, the stirring rate is 120 r / min and the stirring time is 3 h;

[0050] (2) First, add 70 mL of 8 mol / L glycerol solution dropwise to mixed solution A under stirring, then add 2 mL of 1.6 mol / L oxalic acid solution dropwise to the above solution under stirring, and finally obtain mixed solution B;

[0051] The specific stirring conditions are a stirring rate of 200 r / min and a stirring time of 2 h;

[0052] (3) The mixed solution B was subjected to a hydrothermal reaction. Specifically, the mixed solution B was first heated to 140°C at room temperature at a heating rate of 9°C / min and reacted at this temperature for 5 hours. Then, the temperature was increased from 140°C to 180°C at a heating rate of 1°C / min and reacted at this temperature for 19 hours. After the reaction was completed, the reaction product was filtered, washed, and dried at 55°C for 19 hours to obtain biconical molybdenum trioxide powder.

[0053] Example 5:

[0054] (1) Prepare an ammonium molybdate solution with a concentration of 0.95 mol / L using 70 mL of water as the solvent, and prepare a 1-aminoethyl-2-undecylimidazoline hydrochloride solution with a concentration of 30 mol / L using 210 mL of diethylmethanol as the solvent. Under stirring conditions, add the above ammonium molybdate solution dropwise to the 1-aminoethyl-2-undecylimidazoline hydrochloride solution to obtain mixed solution A; wherein, the stirring rate is 160 r / min and the stirring time is 4 h;

[0055] (2) First, add 35 mL of 13 mol / L glycerol solution dropwise to mixed solution A under stirring. Then, add 6 mL of 0.7 mol / L oxalic acid solution dropwise to the above solution under stirring to finally obtain mixed solution B.

[0056] The specific stirring conditions are a stirring rate of 90 r / min and a stirring time of 6 h;

[0057] (3) The mixed solution B was subjected to a hydrothermal reaction. Specifically, the mixed solution B was first heated to 120°C at room temperature at a heating rate of 18°C / min and reacted at this temperature for 5 hours. Then, the temperature was increased from 120°C to 170°C at a heating rate of 0.5°C / min and reacted at this temperature for 15 hours. After the reaction was completed, the reaction product was filtered, washed, and dried at 80°C for 10 hours to obtain biconical molybdenum trioxide powder.

[0058] Figure 1 Figure 1 shows the SEM images of the bipyramidal tungsten trioxide powder prepared in Example 1, where Figure (a) is a low-magnification morphology image and Figure (b) is a high-magnification morphology image. Figure 1 It can be seen that the obtained reaction product is bipyramidal.

[0059] Figure 2 The images shown are TEM images of the bipyramidal tungsten trioxide powder prepared in Example 2. Figure (a) is a low-resolution image and Figure (b) is a high-resolution image. It can be seen that the obtained reaction product is bipyramidal with a lattice spacing of 0.632 nm, corresponding to the (100) crystal plane of tungsten trioxide.

[0060] Figure 3 The XRD pattern of the biconical tungsten trioxide powder prepared in Example 2 corresponds to the card (JCPDS No. 75-2187), proving that the prepared product is tungsten trioxide;

[0061] Figure 4 The response values ​​of the bipyramidal tungsten trioxide powder prepared in Example 3 at different temperatures show that the response value is the highest at 100℃, indicating that the bipyramidal tungsten trioxide powder has the best gas-sensing performance at this temperature.

[0062] Figure 5 The figures show the response values ​​of the biconical tungsten trioxide powder prepared in Example 3 at different concentrations. It can be seen that the gas sensor prepared using the biconical tungsten trioxide powder as a sensitive material can achieve a response value of 96 at 100℃ and 100ppb H2 concentration.

[0063] Figure 6 The response recovery curve of the biconical tungsten trioxide powder prepared in Example 3 shows that the response time of the biconical tungsten trioxide powder is 3s at 100℃ and 100ppb H2 concentration.

[0064] Figure 7 The graph shows a comparison of the hydrogen detection values ​​at low concentrations of the biconical tungsten trioxide powder prepared in Example 3 with other substances disclosed in different literature. It can be seen that the biconical tungsten trioxide powder prepared in this patent, as a gas sensor made from a sensitive material, has excellent gas-sensing performance.

[0065] 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 biconical tungsten trioxide powder, characterized in that: Specifically, the following steps are included: (1) A soluble tungsten salt solution was prepared using water as a solvent, and a 1-aminoethyl-2-undecylimidazoline hydrochloride solution was prepared using diethylmethanol as a solvent. Under stirring conditions, the soluble tungsten salt solution was added dropwise to the 1-aminoethyl-2-undecylimidazoline hydrochloride solution to obtain a mixed solution A. (2) Glycerol solution and oxalic acid solution are added to mixed solution A in sequence to obtain mixed solution B. The addition method is to add dropwise under stirring conditions. The concentration of glycerol solution is 5-20 mol / L and the volume is 10-100 mL. The concentration of oxalic acid solution is 0.3-1.7 mol / L and the volume is 1-6 mL. (3) The mixed solution B is subjected to a hydrothermal reaction. The hydrothermal reaction is a staged reaction. First, the mixed solution B is heated to the first stage reaction temperature at room temperature. The first stage reaction temperature is 120-160℃ and the reaction time is 2-6h. After the first stage reaction is completed, the temperature is raised to the second stage reaction temperature. The second stage reaction temperature is 160-200℃ and the reaction time is 12-24h. After the reaction is completed, the product is filtered, washed and dried to obtain biconical tungsten trioxide powder.

2. The method for preparing biconical tungsten trioxide powder as described in claim 1, characterized in that: The soluble tungsten salt mentioned in step (1) is one or more of ammonium tungstate, sodium tungstate, and potassium tungstate, and the concentration of the soluble tungsten salt solution is 0.12-0.86 mol / L.

3. The method for preparing biconical tungsten trioxide powder as described in claim 1, characterized in that: The volume of diethylmethanol in step (1) is 100-400 mL, and the volume ratio of water to diethylmethanol is less than or equal to 1:

1.

4. The method for preparing biconical tungsten trioxide powder as described in claim 1, characterized in that: The concentration of the 1-aminoethyl-2-undecylimidazoline hydrochloride solution in step (1) is 8-35 mol / L; the specific stirring conditions are a stirring rate of 60-180 r / min and a stirring time of 3-8 h.

5. The method for preparing biconical tungsten trioxide powder as described in claim 1, characterized in that: In step (2), the solvents for the glycerol solution and oxalic acid solution are both deionized water; the specific stirring conditions are a stirring time of 2-6 hours and a stirring rate of 50-200 r / min.

6. The method for preparing biconical tungsten trioxide powder as described in claim 1, characterized in that: In step (3), the drying temperature is 40-80℃ and the drying time is 6-24h.

7. The method for preparing biconical tungsten trioxide powder as described in claim 6, characterized in that: In step (3), the heating rate of mixed solution B to the first stage reaction temperature is 8-20℃ / min at room temperature, and the heating rate of mixed solution B to the second stage reaction temperature is 0.2-1℃ / min after the first stage reaction is completed.

8. A method for preparing bipyramidal molybdenum trioxide powder, characterized in that: According to the preparation method described in any one of claims 1-7, the soluble tungsten salt solution in step (1) is replaced with a soluble molybdenum salt solution. The soluble molybdenum salt is one or more of magnesium molybdate, sodium molybdate, and ammonium molybdate. The concentration of the soluble molybdenum salt solution is 0.25-0.95 mol / L. The product obtained in step (3) is bipyramidal molybdenum trioxide powder.

9. The biconical tungsten trioxide or molybdenum trioxide powder prepared by the preparation method according to any one of claims 1 to 8, characterized in that: Its structure is characterized by highly exposed (100) crystal planes.

10. The application of the biconical tungsten trioxide or molybdenum trioxide powder as described in claim 9 in a hydrogen sensor, characterized in that: The gas sensor prepared using the biconical tungsten trioxide powder or biconical molybdenum trioxide powder as the sensitive material has a response value of 96 and a response time of 3s at an H2 concentration of 100 ppb.

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