A molybdenum-based catalyst and its preparation method and application

Abstract

The present application belongs to the field of catalytic material technology, and specifically relates to a molybdenum-based catalyst, its preparation method and application. The molybdenum-based catalyst provided in the present application includes a substrate, and an active component loaded on the substrate, wherein the active component includes molybdenum dioxide and at least one of a nickel element or a nickel-molybdenum alloy; or, the substrate is loaded with a reducing metal oxide and / or a reducing metal; the morphology of the active component is needle-shaped, rod-shaped or blade-shaped; the size of the active component is nanometer-scale or micrometer-scale. The molybdenum-based catalyst provided in the present application has high catalytic activity for hydrogen production by electrolysis of water, while avoiding the safety hazards caused by hydrogen leakage during the reduction treatment, which is beneficial to the industrial production and application of the catalyst.

Description

Technical Field

[0001] The present application belongs to the technical field of catalytic materials, and specifically relates to a molybdenum-based catalyst and its preparation method and application. Background Art

[0002] Currently, research on hydrogen production catalysts from water electrolysis primarily focuses on precious metal catalysts, non-precious metal catalysts, and composite catalysts. Precious metal catalysts such as platinum and palladium have excellent catalytic activity, but their high cost limits their widespread adoption in large-scale applications. Non-precious metal catalysts, such as transition metal compounds and carbon-based materials, offer lower costs and higher catalytic activity. Currently, molybdenum-based catalysts exhibit excellent catalytic activity and have the potential to replace platinum-on-carbon as hydrogen evolution catalysts.

[0003] In the prior art, the general steps of the preparation method of molybdenum-based catalysts include: first synthesizing a molybdate precursor by a hydrothermal method, and then performing a reduction treatment to obtain a molybdenum-based catalyst. Among them, the reduction step is mostly carried out using hydrogen or other reducing substances. However, the process of hydrogen reduction involves hydrogen management and leakage issues, which poses a major safety hazard, thus limiting the industrial preparation of the catalyst; if other reducing substances are used for reduction, the catalytic activity of the resulting catalyst is low and needs to be further improved. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present application is to overcome the defects in the prior art such as the need to further improve the activity of molybdenum-based catalysts and / or the existence of safety hazards in production, thereby providing a molybdenum-based catalyst and its preparation method and application.

[0005] To this end, this application provides the following technical solutions:

[0006] According to one aspect of the present application, a platinum-based catalyst is provided, comprising a substrate and an active component supported on the substrate.

[0007] Wherein, the active component includes molybdenum dioxide and also includes nickel and / or nickel-molybdenum alloy;

[0008] The active component has a shape of needle, rod or blade; and a size of nanometer or micrometer.

[0009] In some optional embodiments, the substrate supports reducing metal oxides and / or reducing metals.

[0010] In some optional embodiments, the substrate comprises nickel-containing material, iron-containing material, carbon-containing material, preferably nickel foam, nickel mesh, nickel sheet, nickel felt, iron foam, iron mesh, iron sheet, or carbon mesh, carbon cloth.

[0011] According to another aspect of the present application, there is provided a method for preparing a molybdenum-based catalyst, comprising the following steps:

[0012] S1, loading a molybdenum-containing metal component on a substrate under heating conditions to obtain a precursor; wherein the heating temperature is 70-200° C. and the heating time is 1-48 hours;

[0013] As an example, the heating temperature is 70° C., 80° C., 100° C., 130° C., 150° C., 170° C., 200° C., or within a range thereof; the heating time is 1 h, 5 h, 10 h, 15 h, 20 h, 24 h, 26 h, 48 h, or within a range thereof;

[0014] S2 further includes performing at least one of the following (1)-(3):

[0015] (1) Introducing a carbon source during the process of loading the molybdenum-containing metal component on the substrate;

[0016] (2) Introducing a carbon source onto the precursor surface;

[0017] (3) applying a reducing metal to the surface of the precursor;

[0018] S3, heat treatment under protective atmosphere or vacuum conditions;

[0019] It should be noted that the expressions S1, S2 and S3 in the preparation steps are only for the convenience of describing the preparation steps and do not represent the execution order of the steps.

[0020] In this application, it is preferred that any two of (1)-(3) are executed in S2, and more preferably, all three are executed.

[0021] In some optional embodiments, in step S1, the heating temperature is 80-150° C., and the heating time is 5-24 h;

[0022] And / or, in step S3, the heat treatment temperature is 450-900°C and the heat treatment time is 1 second to 2 hours. It should be noted that if the heat treatment time is too short, a device with a particularly fast heating rate needs to be used. For example, if the heat treatment time is 1 second, a Joule heating furnace needs to be used.

[0023] As an example, the heat treatment temperature is 450°C, 500°C, 600°C, 700°C, 800°C, 900°C, or within the range of any of the above values; the heat treatment time is 1s, 30s, 5min, 30min, 1h, 1.5h, 2h, or within the range of any of the above values.

[0024] In the present application, the heat treatment in step S3 can be performed in one step or in multiple stages. When only item (1) is performed in S2, the heat treatment needs to be completed in one step, otherwise, the activity of the catalyst will be affected.

[0025] In some optional embodiments, if one or more of items (1) and (2) in S2 are performed, the heat treatment includes the following steps:

[0026] The temperature is raised to 400-1000° C., preferably 500° C., at a heating rate of 0.01-20° C. / min, preferably 10° C. / min, and maintained for 1 min-2 h, preferably 50 min-2 h.

[0027] In some optional embodiments, in (1) of the above step S2, a carbon source is introduced during the process of loading a molybdenum-containing metal component on a substrate, comprising the following steps: mixing a molybdenum source, a carbon source, and a solvent to obtain a mixed solution A, immersing the substrate in the mixed solution A, soaking, and reacting under heating conditions to obtain a precursor.

[0028] In some optional embodiments, in step (2) of step S2 above, introducing a carbon source onto the surface of the precursor comprises:

[0029] The precursor is immersed in a carbon source solution and dried.

[0030] In some optional embodiments, in step (3) of step S2 above, applying a reducing metal to the surface of the precursor includes:

[0031] The precursor is covered and encapsulated with a reducing metal.

[0032] In the present application, the reducing metal may be reducing metal particles or reducing metal powder, etc. In order to increase the contact area between the reducing metal and the precursor, reducing metal powder is preferably used.

[0033] In some optional embodiments, if (1) introducing a carbon source during the process of loading the molybdenum-containing metal component on the substrate is not performed, then loading the molybdenum-containing metal component on the substrate includes:

[0034] A molybdenum source is mixed with a solvent to obtain a mixed solution B, and a substrate is immersed in the mixed solution B for soaking and reacting under heating conditions to obtain a precursor.

[0035] In some optional embodiments, the mixed solution A and / or the mixed solution B further includes a nickel source.

[0036] In some optional embodiments, the method for preparing the molybdenum-based catalyst satisfies at least one of the following (a)-(j):

[0037] (a) The content of the molybdenum source in the mixed solution A is 10-35 g / L, preferably 12-35 g / L;

[0038] (b) the content of the carbon source in the mixed solution A is 0.1-18 g / L, preferably 3-18 g / L;

[0039] (c) the content of nickel source in the mixed solution A is 0-40 g / L;

[0040] (d) The content of the molybdenum source in the mixed solution B is 10-35 g / L, preferably 12 g / L;

[0041] (e) the content of nickel source in the mixed solution B is 1-40 g / L;

[0042] (f) the carbon source content in the carbon source solution is 0.1-18 g / L, preferably 1-4 g / L;

[0043] (g) The solvent of the mixed solution A and the mixed solution B includes water, and independently includes at least one of an alcohol solvent, hydrogen peroxide, and ammonium fluoride; in the present application, the use of ammonium fluoride is beneficial for the loading of components;

[0044] (h) the reducing metal comprises at least one of aluminum, magnesium, and zinc;

[0045] (i) The substrate comprises nickel foam, iron foam or carbon cloth;

[0046] (j) The soaking time is 0-5h; as an example, the soaking time is 1min, 5min, 20min, 0.5h, 1h, 1.5h, 2h, 3h, 4h, 5h, or any range thereof; the soaking temperature is room temperature, for example, 25°C; in some optional embodiments, an oscillation treatment may be further performed during the soaking process, and the oscillation frequency is 50-200rpm.

[0047] In the present application, the molybdenum source is conventional in the field, including but not limited to at least one of ammonium molybdate, molybdenum trioxide, and molybdenum powder.

[0048] In the present application, the nickel source is a soluble salt containing nickel, including but not limited to at least one of nickel nitrate, nickel sulfate, and nickel chloride.

[0049] In the present application, the carbon source is conventional in the art and can be a carbon-containing organic matter, including but not limited to at least one of glucose, carboxymethyl cellulose, polyvinyl pyrrolidone, p-phenylenediamine, amino acids, sodium alginate, sucrose, etc.

[0050] In the present application, the alcohol solvent is conventional in the field, including but not limited to at least one of methanol, ethanol, isopropanol, etc.

[0051] In the present application, the protective atmosphere is a nitrogen atmosphere or an inert gas atmosphere, such as an argon atmosphere.

[0052] According to another aspect of the present application, there is provided a use of the above-mentioned molybdenum-based catalyst or the molybdenum-based catalyst prepared by the above-mentioned preparation method in hydrogen production by electrolysis of water.

[0053] The technical solution of this application has the following advantages:

[0054] The molybdenum-based catalyst provided in the present application comprises a substrate and an active component loaded on the substrate, wherein the active component comprises molybdenum dioxide and also comprises nickel and / or nickel-molybdenum alloy; alternatively, a reducing metal oxide and / or reducing metal is loaded on the substrate; the morphology of the active component is needle-shaped, rod-shaped or blade-shaped; and the size of the active component is nanometer-scale or micrometer-scale. The molybdenum-based catalyst provided in the present application has a catalytic activity for hydrogen production by electrolysis of water that is much higher than that of similar catalysts obtained by reduction treatment using other reducing substances in the prior art, and is close to the catalytic activity of catalysts obtained by reduction treatment using hydrogen, thus avoiding the safety hazards caused by hydrogen leakage during the reduction treatment and facilitating the industrial production and application of the catalyst.

[0055] The preparation method of the molybdenum-based catalyst provided in the present application can reduce the catalyst in the absence of hydrogen by introducing a carbon source or a reducing metal. This not only maintains the hierarchical structural morphology before heat treatment, but also promotes the reduction of molybdate to conductive molybdenum dioxide, thereby promoting material transport and charge transfer during high-current catalysis and achieving efficient hydrogen evolution catalytic activity. At the same time, this method also avoids the safety hazards caused by hydrogen leakage during heat treatment, which is beneficial to the industrial production and application of the catalyst.

[0056] The preparation method of the molybdenum-based catalyst provided in the present application can better dissolve raw materials such as the molybdenum source, nickel source and / or carbon source by limiting the solvent in the mixed solution A and / or mixed solution B, thereby facilitating the heating reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0058] Figure 1 is the test polarization curve of the platinum-based catalyst provided in Example 1 of the present application;

[0059] Figure 2 is the test polarization curve of the platinum-based catalyst provided in Example 2 of the present application;

[0060] Figure 3 is a scanning electron microscope image of the molybdenum-based catalyst provided in Example 2 of the present application;

[0061] Figure 4 is the test polarization curve of the platinum-based catalyst provided in Example 3 of the present application;

[0062] Figure 5 is the test polarization curve of the platinum-based catalyst provided in Example 4 of the present application;

[0063] Figure 6 is the test polarization curve of the platinum-based catalyst provided in Example 5 of the present application;

[0064] Figure 7 is the test polarization curve of the platinum-based catalyst provided in Example 6 of the present application;

[0065] Figure 8 is the test polarization curve of the platinum-based catalyst provided in Example 7 of the present application;

[0066] Figure 9 is a scanning electron microscope image of the platinum-based catalyst provided in Example 7 of the present application;

[0067] Figure 10 is the test polarization curve of the platinum-based catalyst provided in Example 8 of the present application;

[0068] Figure 11 is the test polarization curve of the platinum-based catalyst provided in Example 9 of the present application;

[0069] Figure 12 is a scanning electron microscope image of the platinum-based catalyst provided in Example 9 of the present application;

[0070] Figure 13 is the test polarization curve of the platinum-based catalyst provided in Example 10 of the present application;

[0071] Figure 14 is a scanning electron microscope image of the platinum-based catalyst provided in Example 10 of the present application;

[0072] Figure 15 is the test polarization curve of the platinum-based catalyst provided in Example 11 of the present application;

[0073] Figure 16 is a scanning electron microscope image of the platinum-based catalyst provided in Example 11 of the present application;

[0074] Figure 17is the test polarization curve of the platinum-based catalyst provided in Example 12 of the present application;

[0075] Figure 18 is a scanning electron microscope image of the platinum-based catalyst provided in Example 12 of the present application;

[0076] Figure 19 is the test polarization curve of the platinum-based catalyst provided in Example 13 of the present application;

[0077] Figure 20 is the XRD spectrum of the platinum-based catalyst provided in Example 13 of the present application;

[0078] Figure 21 is a scanning electron microscope image of the platinum-based catalyst provided in Example 13 of the present application;

[0079] Figure 22 is the test polarization curve of the platinum-based catalyst provided in Example 14 of the present application;

[0080] Figure 23 is the test polarization curve of the platinum-based catalyst provided in Example 15 of the present application;

[0081] Figure 24 is the test polarization curve of the platinum-based catalyst provided in Example 16 of the present application;

[0082] Figure 25 is a scanning electron microscope image of the platinum-based catalyst provided in Example 16 of the present application;

[0083] Figure 26 is the XRD spectrum of the platinum-based catalyst provided in Example 16 of the present application;

[0084] Figure 27 This is the test polarization curve of the catalyst provided in Comparative Example 1 of the present application;

[0085] Figure 28 is a scanning electron microscope image of the catalyst provided in Comparative Example 1 of the present application;

[0086] Figure 29 This is the test polarization curve of the catalyst provided in Comparative Example 2 of the present application;

[0087] Figure 30 is a scanning electron microscope image of the catalyst provided in Comparative Example 2 of the present application;

[0088] Figure 31 is the XRD spectrum of the catalyst provided in Comparative Example 2 of the present application;

[0089] Figure 32 This is the test polarization curve of the catalyst provided in Comparative Example 3 of the present application;

[0090] Figure 33 This is the test polarization curve of the catalyst provided in Comparative Example 4 of the present application. DETAILED DESCRIPTION

[0091] The following examples are provided to further better understand the present application, but are not limited to the best implementation mode described herein, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by anyone under the inspiration of the present application or by combining the features of the present application with other prior arts shall fall within the scope of protection of the present application.

[0092] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0093] Example 1

[0094] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0095] (1) Ammonium molybdate, polyvinyl pyrrolidone (Aladdin, molecular weight 10,000) and water were mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate in the mixed solution was 33 g / L and the mass concentration of polyvinyl pyrrolidone was 6 g / L.

[0096] (2) The nickel foam and the mixed solution were placed in an oscillator, and the nickel foam (thickness 1 mm, 100 PPI) was immersed in the mixed solution and oscillated for 2 h at a frequency of 150 rpm to obtain a white-green suspension; wherein the immersion and oscillation temperature was 25°C.

[0097] (3) The nickel foam and the white-green suspension were placed at 150°C for a hydrothermal reaction for 6 hours to obtain a catalyst precursor; then the temperature was raised to 500°C at a heating rate of 10°C / min and maintained at 500°C for 20 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was pure argon.

[0098] Example 2

[0099] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0100] (1) Ammonium molybdate, carboxymethyl cellulose and water are mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate in the mixed solution is 33 g / L and the mass concentration of carboxymethyl cellulose is 6 g / L.

[0101] (2) The nickel foam and the mixed solution were placed in an oscillator, and the nickel foam was immersed in the mixed solution and oscillated for 2 h at a frequency of 150 rpm to obtain a white-green suspension; wherein the immersion and oscillation temperature was 25°C.

[0102] (3) The nickel foam and the white-green suspension were subjected to a hydrothermal reaction at 150°C for 6 hours to obtain a catalyst precursor; the catalyst precursor was covered with Mg powder and wrapped with aluminum foil, and then heated to 600°C at a heating rate of 10°C / min, and maintained at 600°C for heat treatment for 30 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was pure argon.

[0103] Example 3

[0104] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0105] (1) Ammonium molybdate, p-phenylenediamine and water are mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate in the mixed solution is 33 g / L, and the mass concentration of p-phenylenediamine is 6 g / L.

[0106] (2) The nickel foam and the mixed solution were placed in an oscillator, and the nickel foam was immersed in the mixed solution and oscillated for 2 h at a frequency of 150 rpm to obtain a white-green suspension; wherein the immersion and oscillation temperature was 25°C.

[0107] (3) The nickel foam and the white-green suspension were subjected to a hydrothermal reaction at 150°C for 6 h to obtain a catalyst precursor; the catalyst precursor was soaked in a 2 g / L glucose solution for several minutes and then dried, and then heated to 700°C at a heating rate of 10°C / min and maintained at 700°C for 2 h to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was pure argon.

[0108] Example 4

[0109] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0110] (1) Ammonium molybdate, polyvinyl pyrrolidone (Aladdin, molecular weight 10,000) and water were mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate in the mixed solution was 33 g / L and the mass concentration of polyvinyl pyrrolidone was 3 g / L.

[0111] (2) The nickel foam and the mixed solution were placed in an oscillator, and the nickel foam was immersed in the mixed solution and oscillated for 2 h at a frequency of 150 rpm to obtain a white-green suspension; wherein the immersion and oscillation temperature was 25°C.

[0112] (3) The nickel foam and the white-green suspension were subjected to a hydrothermal reaction at 150°C for 6 h to obtain a catalyst precursor; the catalyst precursor was soaked in a 2 g / L glucose solution for several minutes and then dried, and then heated to 600°C at a heating rate of 10°C / min and maintained at 600°C for 1 h to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was pure argon.

[0113] Example 5

[0114] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0115] (1) Ammonium molybdate, polyvinyl pyrrolidone (Aladdin, molecular weight 10,000) and water were mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate in the mixed solution was 33 g / L and the mass concentration of polyvinyl pyrrolidone was 6 g / L.

[0116] (2) The nickel foam and the mixed solution were placed in an oscillator, and the nickel foam was immersed in the mixed solution and oscillated for 2 h at a frequency of 150 rpm to obtain a white-green suspension; wherein the immersion and oscillation temperature was 25°C.

[0117] (3) The nickel foam and the white-green suspension were subjected to a hydrothermal reaction at 150°C for 6 hours to obtain a catalyst precursor; the catalyst precursor was soaked in 2 g / L polyvinyl pyrrolidone for several minutes and then dried, and then heated to 500°C at a heating rate of 10°C / min, and maintained at 500°C for 20 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was pure argon.

[0118] Example 6

[0119] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0120] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, ammonium fluoride, ethanol and water are mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution is 12 g / L, the mass concentration of nickel nitrate is 40 g / L, the mass concentration of ammonium fluoride is 6 g / L, the total volume of hydrogen peroxide is 5 ml, the total volume of ethanol is 6 ml, and the total volume of water is 7 ml.

[0121] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0122] (3) The catalyst precursor was soaked in a 3 g / L sucrose solution for several minutes and then dried. The temperature was then raised to 850°C in a Joule heating furnace at a rate of 1 second and heat treated for 5 seconds to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was vacuum.

[0123] Example 7

[0124] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0125] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, ammonium fluoride, ethanol and water are mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution is 12 g / L, the mass concentration of nickel nitrate is 40 g / L, the mass concentration of ammonium fluoride is 6 g / L, the total volume of hydrogen peroxide is 5 ml, the total volume of ethanol is 6 ml, and the total volume of water is 7 ml.

[0126] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0127] (3) The catalyst precursor was soaked in a 3 g / L p-phenylenediamine solution for several minutes and then dried. The temperature was then raised to 750° C. in a Joule heating furnace at a rate of 1 second and heat treated for 5 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was vacuum.

[0128] Example 8

[0129] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0130] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, ammonium fluoride, ethanol and water are mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution is 12 g / L, the mass concentration of nickel nitrate is 40 g / L, the mass concentration of ammonium fluoride is 6 g / L, the total volume of hydrogen peroxide is 5 ml, the total volume of ethanol is 6 ml, and the total volume of water is 7 ml.

[0131] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0132] (3) The catalyst precursor was immersed in a 2 g / L polyvinyl alcohol (Aladdin, molecular weight 10,000) solution for several minutes and then dried. The temperature was then raised to 850°C in a Joule heating furnace at a rate of 1 second and heat treated for 5 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was vacuum.

[0133] Example 9

[0134] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0135] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, ammonium fluoride, ethanol and water are mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution is 12 g / L, the mass concentration of nickel nitrate is 40 g / L, the mass concentration of ammonium fluoride is 6 g / L, the total volume of hydrogen peroxide is 5 ml, the total volume of ethanol is 6 ml, and the total volume of water is 7 ml.

[0136] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0137] (3) The catalyst precursor was soaked in a 1 g / L polyvinyl pyrrolidone (Aladdin, molecular weight 10,000) solution for several minutes, dried, covered with reducing metal Al powder and wrapped with aluminum foil, and then heated to 600°C in a Joule heating furnace at a rate of 1 second and heat treated for 10 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was vacuum.

[0138] Example 10

[0139] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0140] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, p-phenylenediamine, ammonium fluoride, ethanol and water are mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution is 12 g / L, the mass concentration of nickel nitrate is 40 g / L, the mass concentration of p-phenylenediamine is 6 g / L, the mass concentration of ammonium fluoride is 3 g / L, the total volume of hydrogen peroxide is 5 ml, the total volume of ethanol is 6 ml, and the total volume of water is 7 ml.

[0141] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0142] (3) The catalyst precursor was soaked in 1 g / L glucose solution for several minutes and then dried, and then heat-treated in a Joule heating furnace at 500°C for 5 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere is vacuum.

[0143] Example 11

[0144] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0145] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, polyvinyl pyrrolidone (Aladdin, molecular weight 10,000), ammonium fluoride, ethanol and water were mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution was 12 g / L, the mass concentration of nickel nitrate was 40 g / L, the mass concentration of polyvinyl pyrrolidone was 6 g / L, the mass concentration of ammonium fluoride was 3 g / L, the total volume of hydrogen peroxide was 5 ml, the total volume of ethanol was 6 ml, and the total volume of water was 7 ml.

[0146] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0147] (3) The catalyst precursor was soaked in 1 g / L glucose solution for several minutes, dried, covered with reducing metal Zn powder, and wrapped with aluminum foil. The temperature was then raised to 500°C in a Joule heating furnace at a rate of 1 second and heat treated for 5 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was vacuum.

[0148] Example 12

[0149] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0150] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, polyvinyl pyrrolidone (Aladdin, molecular weight 10,000), ammonium fluoride, ethanol and water were mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution was 12 g / L, the mass concentration of nickel nitrate was 40 g / L, the mass concentration of polyvinyl pyrrolidone was 12 g / L, the mass concentration of ammonium fluoride was 3 g / L, the total volume of hydrogen peroxide was 5 ml, the total volume of ethanol was 6 ml, and the total volume of water was 7 ml.

[0151] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0152] (3) The catalyst precursor was soaked in a 1 g / L p-phenylenediamine solution for several minutes and then dried. The temperature was then raised to 500° C. in a Joule heating furnace at a rate of 1 second and heat treated for 5 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was vacuum.

[0153] Example 13

[0154] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0155] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, glucose, ammonium fluoride, ethanol and water are mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution is 12 g / L, the mass concentration of nickel nitrate is 40 g / L, the mass concentration of glucose is 12 g / L, the mass concentration of ammonium fluoride is 3 g / L, the total volume of hydrogen peroxide is 5 ml, the total volume of ethanol is 6 ml, and the total volume of water is 7 ml.

[0156] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0157] (3) The catalyst precursor was soaked in 3 g / L sodium alginate solution for several minutes, dried, covered with reducing metal Al powder and wrapped with aluminum foil, and then heated to 500°C in a Joule heating furnace at 1 second and heat treated for 5 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was vacuum.

[0158] Example 14

[0159] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0160] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, polyvinyl pyrrolidone (Aladdin, molecular weight 10,000), ammonium fluoride, ethanol and water were mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution was 12 g / L, the mass concentration of nickel nitrate was 40 g / L, the mass concentration of polyvinyl pyrrolidone was 18 g / L, the mass concentration of ammonium fluoride was 3 g / L, the total volume of hydrogen peroxide was 5 ml, the total volume of ethanol was 6 ml, and the total volume of water was 7 ml.

[0161] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0162] (3) The catalyst precursor was soaked in a 4 g / L glucose solution for several minutes and then dried. The temperature was then raised to 500° C. in a Joule heating furnace at a rate of 1 second and heat treated for 5 minutes to obtain a molybdenum-based catalyst. The heat treatment atmosphere was vacuum.

[0163] Example 15

[0164] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0165] (1) Ammonium molybdate, nickel nitrate and a sucrose aqueous solution are mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate is 30 g / L, the mass concentration of nickel nitrate is 30 g / L, and the mass concentration of sucrose is 9 g / L.

[0166] (2) The nickel foam and the mixed solution were placed in a reactor and subjected to a hydrothermal reaction at 150°C for 6 hours to obtain a catalyst precursor.

[0167] (3) The catalyst precursor was soaked in 1 g / L glucose solution, dried, covered with reducing metal Mg powder, and wrapped with aluminum foil. It was then heat-treated in a Joule heating furnace at 500°C for 5 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was vacuum.

[0168] Example 16

[0169] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0170] (1) Ammonium molybdate, nickel nitrate and water are mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate in the mixed solution is 30 g / L, and the mass concentration of nickel nitrate is 30 g / L.

[0171] (2) The nickel foam and the mixed solution were placed in a reactor and subjected to a hydrothermal reaction at 150°C for 6 hours to obtain a catalyst precursor.

[0172] (3) The catalyst precursor was covered with reducing metal Mg powder and wrapped with aluminum foil, and then heated to 500°C in a tubular furnace at a heating rate of 5°C / min, and maintained at this temperature for 20 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was pure argon.

[0173] Example 17

[0174] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0175] (1) Ammonium molybdate, nickel nitrate, polyvinyl pyrrolidone and water are mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate in the mixed solution is 35 g / L, the mass concentration of nickel nitrate is 30 g / L, and the mass concentration of polyvinyl pyrrolidone is 6 g / L.

[0176] (2) The foamed iron and the mixed solution were placed in an oscillator, and the foamed iron was immersed in the mixed solution and oscillated for 2 h at a frequency of 150 rpm to obtain a white-green suspension; wherein the immersion and oscillation temperature was 25°C.

[0177] (3) The foamed iron and the white-green suspension were placed at 140°C for a hydrothermal reaction for 5 hours to obtain a catalyst precursor; the temperature was then raised to 500°C at a heating rate of 10°C / min and maintained at 500°C for a heat treatment for 20 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was pure argon.

[0178] Example 18

[0179] This embodiment provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0180] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, polyvinyl pyrrolidone, ammonium fluoride, ethanol and water are mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution is 12 g / L, the mass concentration of nickel nitrate is 40 g / L, the mass concentration of polyvinyl pyrrolidone is 12 g / L, the mass concentration of ammonium fluoride is 3 g / L, the total volume of hydrogen peroxide is 5 ml, the total volume of ethanol is 6 ml, and the total volume of water is 7 ml.

[0181] (2) The carbon cloth and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction lasted for 24 hours to obtain a catalyst precursor.

[0182] (3) The catalyst precursor was soaked in a 1 g / L p-phenylenediamine solution for several minutes and then dried. The temperature was then raised to 500° C. in a Joule heating furnace at a rate of 1 second and heat treated for 5 minutes to obtain a molybdenum-based catalyst; wherein the heat treatment atmosphere was vacuum.

[0183] Comparative Example 1

[0184] This comparative example provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0185] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, ammonium fluoride, ethanol and water are mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution is 12 g / L, the mass concentration of nickel nitrate is 40 g / L, the mass concentration of ammonium fluoride is 3 g / L, the total volume of hydrogen peroxide is 5 ml, the total volume of ethanol is 6 ml, and the total volume of water is 7 ml.

[0186] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0187] (3) Wrapping the catalyst precursor with aluminum foil, heating it to 500° C. in a Joule heating furnace for 1 second, and calcining it for 3 minutes to obtain a molybdenum-based catalyst; wherein the treatment atmosphere is vacuum.

[0188] Comparative Example 2

[0189] This comparative example provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0190] (1) Ammonium molybdate, nickel nitrate and water are mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate in the mixed solution is 30 g / L, and the mass concentration of nickel nitrate is 30 g / L.

[0191] (2) The nickel foam and the mixed solution were placed in a reactor and subjected to a hydrothermal reaction at 150°C for 6 hours to obtain a catalyst precursor.

[0192] (3) Wrap the catalyst precursor with aluminum foil, heat it to 500°C in a tubular furnace at a heating rate of 5°C / min, maintain the temperature, and calcine for 20 minutes to obtain a molybdenum-based catalyst; wherein the treatment atmosphere is pure argon.

[0193] Comparative Example 3

[0194] This comparative example provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0195] (1) Ammonium molybdate, polyvinyl pyrrolidone (Aladdin, molecular weight 10,000) and water were mixed to obtain a mixed solution, wherein the mass concentration of ammonium molybdate in the mixed solution was 33 g / L and the mass concentration of polyvinyl pyrrolidone was 6 g / L.

[0196] (2) The nickel foam and the mixed solution were placed in an oscillator, and the nickel foam (thickness 1 mm, 100 PPI) was immersed in the mixed solution and oscillated for 2 h at a frequency of 150 rpm to obtain a white-green suspension; wherein the immersion and oscillation temperature was 25°C.

[0197] (3) The nickel foam and the white-green suspension were subjected to a hydrothermal reaction at 150°C for 6 hours to obtain a catalyst precursor; the temperature was first kept constant at 250°C for 1 hour, and then the temperature was increased to 500°C and kept constant for 20 minutes; the atmosphere for the heat treatment was pure argon.

[0198] Comparative Example 4

[0199] This comparative example provides a method for preparing a molybdenum-based catalyst, and the specific steps and operating parameters are as follows:

[0200] (1) Molybdenum trioxide, nickel nitrate, hydrogen peroxide, p-phenylenediamine, ammonium fluoride, ethanol and water are mixed to obtain a mixed solution, wherein the mass concentration of molybdenum trioxide in the mixed solution is 12 g / L, the mass concentration of nickel nitrate is 40 g / L, the mass concentration of p-phenylenediamine is 6 g / L, the mass concentration of ammonium fluoride is 3 g / L, the total volume of hydrogen peroxide is 5 ml, the total volume of ethanol is 6 ml, and the total volume of water is 7 ml.

[0201] (2) The nickel foam and the mixed solution were placed in a glass vial and reacted at 80°C. The liquid level was kept constant during the reaction. The reaction was continued for 24 hours to obtain a catalyst precursor.

[0202] (3) The catalyst precursor was soaked in a 1 g / L glucose solution for several minutes, dried, and wrapped in aluminum foil. The catalyst was then heated in stages in a tubular furnace to obtain a molybdenum-based catalyst. The temperature was first maintained at 250°C for 1 hour, then raised to 500°C and maintained at this temperature for 20 minutes to obtain the molybdenum-based catalyst. The heat treatment atmosphere was vacuum.

[0203] Table 1

[0204]

[0205] Note: “ / ” represents that the corresponding component was not introduced.

[0206] Test Case

[0207] The catalysts provided in each embodiment and comparative example of the present application were subjected to XRD, SEM and catalytic performance tests. The specific test methods are as follows:

[0208] 1. XRD uses Bruker D8 advance with a scanning range of 5-80 degrees;

[0209] 2. Scanning electron microscopy was performed using a Zeiss electron microscope (Gemini 450 microscope system);

[0210] 3. Catalytic performance

[0211] A three-electrode test method was used, with the catalyst (from each Example and Comparative Example) serving as the cathode, a graphite sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. Measurements were performed in a glass electrolytic cell with a 1 mol / L potassium hydroxide solution as the electrolyte. Linear sweep voltammetry was performed from 0 V to -0.4 V at a sweep rate of 5 mV / s.

[0212] Specific test results such as Figure 1-Figure 33 As shown, Figure 1 , 2, 4, 5, 6, 7, 8, 10, 11, 13, 15, 17, 19, 22, 23, 24, 27, 29, 32, 33 are the test polarization curves of Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 and Comparative Examples 1, 2, 3, 4 respectively; Figure 3 , 9, 12, 14, 16, 18, 21, 25, 28, 30 are scanning electron microscope images of Examples 2, 7, 9, 10, 11, 12, 13, 16 and Comparative Examples 1 and 2; Figure 20 , 26, 31 are XRD patterns of Examples 13, 16 and Comparative Example 2. From the polarization curves, it can be seen that Examples 1-16 have a high 2The overpotential at a current density of 1.5 is significantly lower than that of Comparative Examples 1 and 2 without heat treatment; and the performance is better than that of Comparative Examples 3 and 4 obtained by staged reduction. In addition, it can be seen from the scanning electron microscope images that the various reduction treatment methods used in this application can still well maintain the nanomorphology of the catalyst hierarchical structure, thereby ensuring efficient material transfer and charge transport under high current density. From the XRD diagram, it can be seen that, in combination with various heat treatment methods, Example 13 can be completely reduced to a heterogeneous structure of molybdenum dioxide and nickel-molybdenum alloy. Although Example 16 is not completely reduced, it still has obvious molybdenum dioxide phase and metal phase. For Comparative Example 2, there is no obvious reduction effect.

[0213] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a molybdenum-based catalyst, characterized in that: The active components of the molybdenum-based catalyst include molybdenum dioxide and nickel and / or nickel-molybdenum alloy; the preparation method includes the following steps: S1, mixing a molybdenum source, a carbon source, and a solvent to obtain a mixed solution A, immersing a substrate in the mixed solution A, soaking, reacting under heating conditions to obtain a precursor, applying a reducing metal on the surface of the precursor, and covering and wrapping the precursor with the reducing metal, wherein the reducing metal includes at least one of aluminum, magnesium, and zinc; wherein the heating temperature is 70-200° C. and the heating time is 1-48 hours; S2, heat treatment under protective atmosphere or vacuum conditions; or, S1, mixing a molybdenum source with a solvent to obtain a mixed solution B, immersing a substrate in the mixed solution B, soaking, reacting under heating conditions to obtain a precursor, immersing the precursor in a carbon source solution, drying, applying a reducing metal, and covering and wrapping the precursor with the reducing metal, wherein the reducing metal includes at least one of aluminum, magnesium, and zinc; wherein the heating temperature is 70-200° C. and the heating time is 1-48 hours; S2, heat treatment under protective atmosphere or vacuum conditions; or, S1, mixing a molybdenum source, a carbon source, and a solvent to obtain a mixed solution A, immersing a substrate in the mixed solution A, soaking, reacting under heating conditions to obtain a precursor, immersing the precursor in a carbon source solution, drying, applying a reducing metal, and covering and wrapping the precursor with the reducing metal, wherein the reducing metal includes at least one of aluminum, magnesium, and zinc; wherein the heating temperature is 70-200° C. and the heating time is 1-48 hours; S2, heat treatment is carried out under protective atmosphere or vacuum conditions.

2. The method for preparing a platinum-based catalyst according to claim 1, wherein In step S1, the heating temperature is 80-150° C., and the heating time is 5-24 hours.

3. The method for preparing a platinum-based catalyst according to claim 1, wherein In step S2, the heat treatment temperature is 450-900° C., and the heat treatment time is 1 second to 2 hours.

4. The method for preparing a platinum-based catalyst according to claim 1, wherein The mixed solution A and / or the mixed solution B further includes a nickel source.

5. The method for preparing a platinum-based catalyst according to claim 4, wherein Satisfy at least one of the following (a)-(i): (a) The content of the molybdenum source in the mixed solution A is 10-35 g / L; (b) the content of the carbon source in the mixed solution A is 0.1-18 g / L; (c) the content of nickel source in the mixed solution A is 0-40 g / L; (d) the content of the molybdenum source in the mixed solution B is 10-35 g / L; (e) the content of nickel source in the mixed solution B is 1-40 g / L; (f) the carbon source content in the carbon source solution is 0.1-18 g / L; (g) the solvent of the mixed solution A and the mixed solution B includes water, and independently includes at least one of an alcohol solvent, hydrogen peroxide, and ammonium fluoride; (h) The substrate comprises nickel foam, iron foam or carbon cloth; (i) The soaking time is 0-5 hours.

6. A molybdenum-based catalyst prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the molybdenum-based catalyst according to claim 6 in producing hydrogen by electrolysis of water.

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