Catalyst for hydrogen production by electrolysis of water, method for its preparation and use

Abstract

The application relates to the technical field of catalysts, and discloses a catalyst for electrolyzing water to produce hydrogen as well as a preparation method and application of the catalyst. The catalyst contains active metal elements Pt and a carrier WO3 nanorod; the active metal elements Pt are dispersed on the carrier WO3 nanorod in the form of nanoparticles; the content of Pt is 1-10 wt% based on the total mass of the catalyst; the average diameter of the Pt nanoparticles in the catalyst is 1-5 nm; and the oxygen vacancy content of the catalyst is 12-20%. The catalyst provided by the application can provide continuous proton transmission and electron transmission channels, greatly reduces the platinum loading in the cathode catalytic layer of a membrane electrode, significantly improves the activity of a proton exchange membrane in the cathode reaction of water electrolysis, improves the comprehensive efficiency of a proton exchange membrane water electrolysis cell, and improves the efficiency of a water electrolysis device; and the method for preparing the catalyst is simple in operation, environment-friendly, easy to control and large-scaled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a catalyst for water electrolysis hydrogen production, a preparation method and application thereof. BACKGROUND

[0002] Hydrogen, with its clean, abundant and high energy density, is becoming a promising energy carrier. However, the use of fossil fuels (i.e. coal and natural gas) to produce hydrogen through steam reforming is an important source of large CO2 emissions. In contrast, electrolysis cells, which utilize zero-emission wind / solar resources, provide an eco-friendly alternative for the electrolysis reaction of water decomposition into H2, and water electrolysis hydrogen production is considered to be a next-generation energy technology with great potential.

[0003] The current common water electrolysis hydrogen production technologies include alkaline water electrolysis (AWE), proton exchange membrane water electrolysis (PEMWE) and high-temperature solid oxide water electrolysis (SOEC) and the like. Compared with alkaline water electrolysis and SOEC water electrolysis, PEM water electrolysis cells have higher advantages such as tolerance to pressure difference, current fluctuation and system shutdown and cold start, and can maintain standby mode with the lowest power, which has good matching with wind power and photovoltaic power with greater volatility and randomness. Since the PEM electrolysis cell is in a strong acidic environment and needs to withstand a very high voltage (usually greater than 2V), the selection range of PEMWE component materials becomes narrow, and only some precious metal catalyst materials (Pt, Ir, Ru) and Ti material current collectors can meet the use requirements, which greatly increases the cost of water electrolysis devices.

[0004] Therefore, in view of the key problem of high precious metal loading in the PEMWE membrane electrode, it is necessary to propose a strategy to reduce the platinum loading in the cathode catalyst layer of the membrane electrode and improve the efficiency of the water electrolysis device.

[0005] CN11788142A discloses a catalytic material, characterized in that it comprises: a carrier; noble metal nanoparticles anchored on the surface of the carrier; an amorphous oxide layer coated on the surface of the noble metal nanoparticles; the composition of the amorphous oxide layer is MOx, the M is one of Mo, W and V; the noble metal nanoparticles are one of Pt, Pd, Ru, Rh or Ir nanoparticles, and the particle size of the nanoparticles is not greater than 4nm. Although this scheme tries different metal oxide carriers with similar methods and selects the amorphous Mo oxide wrapped noble metal Pt particle catalytic material with higher catalytic activity, it does not verify that it can be applied in PEMWE with ultra-low loading.

[0006] CN111298790A discloses a hydrogen evolution reaction catalyst, characterized in that the hydrogen evolution reaction catalyst takes WO3 as the main body of a non-metallic catalyst, and WO3 is a WO3 nanosheet structure grown in situ on a flexible self-supporting substrate, and further includes Pt loaded on the WO3 nanosheet in the form of an atomic cluster to form a WO3 oxygen defect surface. This scheme uses carbon fiber cloth as the substrate to synthesize the carrier and then impregnates and loads platinum. The production of the hydrothermal amplification using carbon cloth as the substrate has limitations. Although the content of platinum in the synthesized catalyst is low, the electrochemical hydrogen evolution activity is poor, and the mass activity is low. In the application of this scheme, the platinum loading is only reduced to 1 / 3 of the commercial platinum loading; and the application effect in PEMWE cannot be expected.

[0007] CN111111658A discloses a single-atom Pt supported tungsten oxide monolayer nanosheet catalyst with ultra-high catalytic activity, characterized in that the micro-morphology of the catalyst is that single-atom Pt is uniformly dispersed on tungsten oxide monolayer nanosheets to form a monolayer nanosheet with a thickness of 0.7-1.3 nm. In this scheme, the tungsten oxide is in a cubic phase, and the synthesis method is complex, time-consuming, multi-process and high-energy-consuming. In this scheme, platinum is dispersed in the form of single atoms on tungsten oxide nanosheets, and the platinum content in the catalyst is extremely low. Its catalytic activity has not been verified at high current density, and its stability is poor. The application effect in PEMWE cannot be expected. SUMMARY

[0008] The purpose of the present application is to solve the problems of high platinum loading, low utilization rate and low catalytic efficiency of the existing electrolytic water hydrogen evolution reaction catalyst applied to a proton exchange membrane water electrolysis tank.

[0009] To achieve the above-mentioned purpose, the first aspect of the present application provides a catalyst for electrolytic water hydrogen production, which contains active metal element Pt and carrier WO3 nanorods; the active metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles; the content of Pt is 1-10wt% based on the total mass of the catalyst.

[0010] The average diameter of the Pt nanoparticles in the catalyst is 1-5 nm, and the oxygen vacancy content of the catalyst is 12-20%.

[0011] The second aspect of the present application provides a method for preparing the catalyst of the first aspect, which comprises:

[0012] (1) mixing a sodium tungstate dihydrate aqueous solution with sulfuric acid to obtain a first solution; the concentration of the sodium tungstate dihydrate solution is 30-40 mg / mL; the amount of sulfuric acid is such that the pH value of the first solution is 1-2;

[0013] (2) reacting a directing agent with the first solution, and subjecting the obtained product to first drying to obtain WO3 nanorods; the mass ratio of the sodium tungstate dihydrate to the directing agent is 1:3-4; the reaction conditions include: temperature of 160-190℃, time of 10-24h;

[0014] (3) third mixing a platinum source with the WO3 nanorods in the presence of water, and subjecting the obtained product to second drying to obtain a catalyst precursor; the mass ratio of the platinum source to the WO3 nanorods is 1:10-40 in terms of platinum element and WO3 nanorods respectively;

[0015] (4) subjecting the catalyst precursor to reduction treatment to obtain the catalyst.

[0016] The third aspect of the present application provides the catalyst prepared by the method of the second aspect.

[0017] The fourth aspect of the present application provides the application of the catalyst of the first aspect and / or the third aspect in the water electrolysis hydrogen production reaction.

[0018] The WO3 nanorods in the catalyst provided by the present application provide abundant oxygen vacancies for Pt, which provides abundant anchoring sites for Pt, and Pt is highly dispersed on the surface of the WO3 nanorods, so that the specific surface area is large and the efficiency of Pt element can be fully utilized.

[0019] The catalyst provided by the present application can provide a continuous proton transmission and electron transmission channel, greatly reduces the platinum loading in the membrane electrode cathode catalytic layer, significantly improves the activity of the proton exchange membrane water electrolysis cathode reaction at a lower platinum loading, improves the comprehensive efficiency of the proton exchange membrane water electrolysis cell, and improves the efficiency of the water electrolysis device.

[0020] Further, the method for preparing the catalyst provided by the present application is simple in operation, environmentally friendly, easy to control and scalable. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the electron microscope image of the WO3 nanorods and the catalyst obtained in Example 1 provided by the present application;

[0022] Figure 2 is the electron microscope image of the catalyst obtained in Example 2 provided by the present application;

[0023] Figure 3 is the electron microscope image of the WO3 nanorods and the catalyst obtained in Example 3 provided by the present application;

[0024] Figure 4 is the electron microscope image of the WO3 nanorods obtained in Example 4 provided by the present application;

[0025] Figure 5 is a TEM image of the catalyst obtained from Example 6, which is exemplarily provided in the present application;

[0026] Figure 6 is a TEM image of the WO3 support obtained from Comparative Example 2, which is exemplarily provided in the present application;

[0027] Figure 7 is a TEM image of the WO3 support obtained from Comparative Example 5, which is exemplarily provided in the present application;

[0028] Figure 8 is a HRTEM image of the WO3 nanorods and catalyst obtained from Example 1, which is exemplarily provided in the present application;

[0029] Figure 9 is an EDS image of the catalyst obtained from Example 1, which is exemplarily provided in the present application;

[0030] Figure 10 is an XPS image of the catalyst obtained from Example 1, which is exemplarily provided in the present application;

[0031] Figure 11 is an XPS image of the catalyst obtained from Comparative Example 4, which is exemplarily provided in the present application;

[0032] Figure 12 is a comparison of XRD images of the catalysts obtained from Example 1, Example 2 and Comparative Example 3, which is exemplarily provided in the present application;

[0033] Figure 13 is a comparison of polarization curves of the catalysts obtained from Example 1 and Comparative Example 4, which is exemplarily provided in the present application. DETAILED DESCRIPTION

[0034] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are understood to be approximate values. The exact numerical values of the endpoints of the ranges and any values are approximations which are now to be understood to include values approximately the same as the stated values. For example, the endpoints of the ranges of values are not limited to the precise values stated, but include values which are approximately the same as the stated values. The ranges of values are understood to include values which are approximately the same as the stated values. The exact numerical values of the endpoints of the ranges and any values are approximations which are now to be understood to include values approximately the same as the stated values.

[0035] As described previously, the first aspect of the present application provides a catalyst for hydrogen production by electrolysis of water, which contains an active metal element Pt and a support WO3 nanorod; the active metal element Pt is dispersed on the support WO3 nanorod in the form of nanoparticles; the content of the Pt is 1-10 wt% based on the total mass of the catalyst.

[0036] The average diameter of the Pt nanoparticles in the catalyst is 1-5 nm, and the oxygen vacancy content of the catalyst is 12-20%.

[0037] Preferably, the content of Pt is 3-4 wt% based on the total mass of the catalyst.

[0038] More preferably, the average diameter of the Pt nanoparticles in the catalyst is 1-2 nm, and the oxygen vacancy content of the catalyst is 16.5-17.2%.

[0039] Further preferably, the average length of the WO3 nanorods is 100-200 nm, and the average diameter is 10-20 nm.

[0040] As described before, the second aspect of the present application provides a method for preparing the catalyst of the aforementioned first aspect, the method comprising:

[0041] (1) performing a first mixing of an aqueous sodium tungstate dihydrate solution and sulfuric acid to obtain a first solution; the concentration of the aqueous sodium tungstate dihydrate solution is 30-40 mg / mL; the amount of the sulfuric acid is such that the pH value of the first solution is 1-2;

[0042] (2) performing a reaction of a directing agent with the first solution, and performing a first drying of the obtained product to obtain WO3 nanorods; the mass ratio of the amount of the aqueous sodium tungstate dihydrate solution to the amount of the directing agent is 1:3-4; the reaction conditions include: a temperature of 160-190°C, and a time of 10-24 h;

[0043] (3) performing a third mixing of a platinum source and the WO3 nanorods in the presence of water, and performing a second drying of the obtained product to obtain a catalyst precursor; the mass ratio of the amount of the platinum source to the amount of the WO3 nanorods is 1:10-40, in terms of platinum element and WO3 nanorods, respectively;

[0044] (4) performing a reduction treatment of the catalyst precursor to obtain the catalyst.

[0045] Preferably, in step (1), the concentration of the sulfuric acid is 3-5 mol / L.

[0046] Preferably, the conditions of the first mixing include: a temperature of 25-30°C.

[0047] More preferably, the first mixing is performed under stirring, and the speed of the stirring is 200-500 rpm, and the time is 0.25-0.5 h.

[0048] Preferably, in step (2), the directing agent is a combination of a sulfate and dihydrate oxalic acid in a molar ratio of 3-4:1; the sulfate is selected from at least one of ammonium sulfate and sodium sulfate; more preferably, the sulfate is ammonium sulfate. The inventors have found that, in this preferred specific embodiment, the catalyst obtained by the present application has better catalytic activity, and has a higher current density when applied to a water electrolysis device.

[0049] Preferably, in step (2), the reaction is carried out in a reactor, and the reaction conditions include: temperature of 175-185℃, time of 10-12h.

[0050] Preferably, the reaction is carried out under stirring, and the stirring speed is 200-500rpm.

[0051] More preferably, in step (2), the method further comprises: before the reaction, mixing the directing agent with the first solution for a second mixing, and the second mixing conditions include: stirring speed of 200-500rpm, time of 20-30min, and temperature of 20-30℃.

[0052] It should be noted that, in step (2), the present application does not have special requirements for the reactor, which can meet the high temperature and high pressure required for the reaction. The present application will not be described here, and those skilled in the art should not be construed as limiting the present application.

[0053] Preferably, in step (3), the platinum source is selected from at least one of H2PtCl6·6H2O, potassium chloroplatinate, and cisplatin.

[0054] More preferably, the platinum source is an aqueous solution of platinum source with a concentration of 10-30mg / mL.

[0055] Preferably, in step (3), the amount of water is 20-40mL relative to 100mg of WO3nanorods.

[0056] Preferably, the third mixing is carried out under stirring, and the third mixing conditions include: temperature of 50-90℃, more preferably 60-90℃; and time of 10-14h, more preferably 11-12h. The inventors have found that, in this preferred embodiment, the catalyst obtained by the present application has more active sites exposed, the dispersion of platinum is more uniform, and the electrochemical performance is better when applied to an electrolytic water device.

[0057] Preferably, in step (4), the reduction treatment is carried out in the presence of a reducing atmosphere, and the reduction treatment conditions include: heating rate of 2-5℃ / min, temperature of 350-450℃, and time of 3-5h.

[0058] More preferably, the reducing atmosphere is a combination of hydrogen and argon, and the content of hydrogen is 4-6% by volume.

[0059] As described above, the third aspect of the present application provides a catalyst prepared by the method of the aforementioned second aspect.

[0060] As described above, the fourth aspect of the present application provides the use of the catalyst of the first aspect and / or the third aspect in the reaction of electrolysis of water to produce hydrogen.

[0061] Preferably, the catalyst is used in the reaction of electrolysis of water to produce hydrogen in a proton exchange membrane;

[0062] More preferably, the loading of the catalyst in the membrane electrode is not higher than 0.05 mg / cm 2 .

[0063] The present application will be described in detail below by way of examples. In the following examples, the raw materials and equipment used are commercially available and are of analytical purity unless otherwise specified.

[0064] Example 1

[0065] This example is used to illustrate the preparation of the catalyst for electrolysis of water to produce hydrogen provided by the present application using the following steps:

[0066] (1) Dissolve 1.32 g of sodium tungstate dihydrate in 40 mL of water to obtain a sodium tungstate dihydrate aqueous solution with a concentration of 33 mg / mL, then perform first mixing with concentrated sulfuric acid (the stirring speed is 300 rpm, the time is 1 h, and the temperature is 25°C) to obtain a first solution; the amount of the sulfuric acid is such that the pH value of the first solution is 1;

[0067] (2) In a reaction kettle, perform second mixing of the directing agent with the first solution (the stirring speed is 400 rpm, the time is 30 min, and the temperature is 25°C) and then perform reaction, and then perform first drying (50°C for 5 h) on the obtained product to obtain WO3 nanorods;

[0068] The mass ratio of the amount of the sodium tungstate dihydrate to the directing agent is 1:3.8;

[0069] The reaction conditions are: the temperature is 180°C, and the time is 10 h;

[0070] The directing agent is a combination of ammonium sulfate and oxalic acid dihydrate with a molar ratio of 4:1;

[0071] (3) Disperse 100 mg of the WO3 nanorods in 30 mL of water, then perform third mixing with a chloroplatinic acid aqueous solution with a concentration of 30 mg / mL, and then perform rotary evaporation and second drying (50°C for 5 h) on the obtained product in sequence to obtain a catalyst precursor;

[0072] The mass ratio of the amount of the platinum source to the WO3 nanorods is 1:33.3 in terms of platinum element and WO3 nanorods, respectively;

[0073] The third mixing condition is that the temperature is 80℃, the time is 12h, and the stirring speed is 500rpm;

[0074] (4) The catalyst precursor is subjected to reduction treatment to obtain the catalyst S1;

[0075] The reduction treatment condition is that the reduction atmosphere is a combination of 5% by volume of hydrogen and 95% by volume of argon, the temperature rising rate is 5℃ / min, the temperature is 400℃, and the time is 4h.

[0076] Example 2

[0077] (1) 1.32g of sodium tungstate dihydrate is dissolved in 33mL of water to obtain a sodium tungstate dihydrate aqueous solution with a concentration of 40mg / mL, which is then subjected to first mixing (stirring speed is 500rpm, time is 0.5h, and temperature is 25℃) with concentrated sulfuric acid with a concentration of 5mol / L to obtain a first solution; the amount of the sulfuric acid is such that the pH value of the first solution is 1.5;

[0078] (2) In a reaction kettle, the directing agent is subjected to second mixing (stirring speed is 400rpm, time is 30min, and temperature is 25℃) with the first solution, and then subjected to reaction, and the obtained product is subjected to first drying (50℃ for 5h) to obtain WO3 nanorods;

[0079] The mass ratio of the amount of the sodium tungstate dihydrate to the directing agent is 1:3.5;

[0080] The reaction condition is that the temperature is 170℃, and the time is 12h;

[0081] The directing agent is a combination of ammonium sulfate and dihydrate oxalic acid with a molar ratio of 3:1;

[0082] (3) 100mg of the WO3 nanorods is dispersed in 30mL of water, which is then subjected to third mixing with a chloroplatinic acid aqueous solution with a concentration of 20mg / mL, and the obtained product is subjected to rotary evaporation and second drying (50℃ for 5h) in sequence to obtain a catalyst precursor;

[0083] The mass ratio of the amount of the platinum source to the WO3 nanorods is 1:11 in terms of platinum element and WO3 nanorods respectively;

[0084] The third mixing condition is that the temperature is 60℃, the time is 11h, and the stirring speed is 500rpm;

[0085] (4) The catalyst precursor is subjected to reduction treatment to obtain the catalyst S2;

[0086] The reducing treatment is performed under the following conditions: a reducing atmosphere of 5 vol% hydrogen and 95 vol% argon, a temperature ramping rate of 2°C / min, a temperature of 450°C, and a time of 5 h.

[0087] Example 3

[0088] This example was performed using a similar procedure to Example 1, except that in this example, the directing agent was a combination of sodium sulfate and oxalic acid dihydrate in a mass ratio of 4:1.

[0089] The rest was the same as Example 1.

[0090] Catalyst S3 was prepared.

[0091] Example 4

[0092] This example was performed using a similar procedure to Example 1, except that in this example, in step (2), the reaction was performed for 24 h.

[0093] The rest was the same as Example 1.

[0094] Catalyst S4 was prepared.

[0095] Example 5

[0096] This example was performed using a similar procedure to Example 1, except that in this example, in step (3), the third mixture was at a temperature of 25°C.

[0097] The rest was the same as Example 1.

[0098] Catalyst S5 was prepared.

[0099] Example 6

[0100] This example was performed using a similar procedure to Example 1, except that in this example, the reducing treatment was performed under the following conditions: a reducing atmosphere of N2.

[0101] The rest was the same as Example 1.

[0102] Catalyst S6 was prepared.

[0103] Comparative Example 1

[0104] This comparative example was performed using a similar procedure to Example 1, except that in this comparative example, tungstic acid was used instead of sodium tungstate dihydrate in Example 1.

[0105] The rest was the same as Example 1.

[0106] Catalyst DS1 was prepared.

[0107] Comparative Example 2

[0108] The comparative example was carried out by using a similar procedure as in Example 1, except that in the comparative example, in step (1), the amount of sulfuric acid was used so that the pH value of the first solution was 0.3.

[0109] The rest was the same as in Example 1.

[0110] The catalyst DS2 was prepared.

[0111] Comparative Example 3

[0112] The comparative example was carried out by using a similar procedure as in Example 1, except that in the comparative example, the catalyst prepared did not contain platinum element, and the specific preparation steps were as follows:

[0113] (1) The same as in Example 1;

[0114] (2) The same as in Example 1;

[0115] (3) 100 mg of WO3 nanorods was reduced (the reduction conditions were the same as in Example 1), to obtain the material DS3.

[0116] Comparative Example 4

[0117] Commercial Pt / C (mass content of Pt was 40%) was purchased from Zhengzhou Alpha Chemical Co., Ltd.

[0118] Comparative Example 5

[0119] The example was carried out by using a similar procedure as in Example 1, except that in the example, in step (2), the reaction conditions were as follows: the temperature was 150°C.

[0120] The rest was the same as in Example 1.

[0121] The catalyst DS5 was prepared.

[0122] The composition and parameter characteristics of the catalysts prepared in each of the above examples are shown in Table 1; wherein the content of Pt element was detected by ICP-MS detector.

[0123] Table 1

[0124]

[0125] Table 1 (continued)

[0126]

[0127]

[0128] Note: " / " in Table 1 means not detected or no actual detection significance.

[0129] The present application also exemplarily provides the electron microscope images of the catalyst prepared by the above example, Figure 1 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 1 Figure 1 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 1 Figure 1 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 1

[0130] The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 2 Figure 2 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles.

[0131] Figure 3 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 3 Figure 3 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 3 Figure 3 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 3 Figure 3 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles.

[0132] The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 4 Figure 4 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles.

[0133] The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 5 Figure 6 The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles.

[0134] The electron microscope images of the WO3 nanorods (a) and (b) in the WO3 nanorods (c) and (d) in the catalyst provided for Example 1, from which it can be seen that the prepared WO3 carrier is in the form of nanorods, and the metal element Pt is dispersed on the carrier WO3 nanorods in the form of nanoparticles. Figure 6 Figure 6 ​​​​​​As can be seen from the data, in step (1), when the pH value of the first solution is 0.3, the prepared sample has an irregular morphology.

[0135] Figure 7 For the WO3 carrier provided in Comparative Example 5, from Figure 7 It is quite obvious that the prepared sample has an irregular morphology.

[0136] Figure 8 The images show HRTEM images of the WO3 nanorods and catalyst prepared in Example 1. (a), (b), and (c) are HRTEM images of the WO3 nanorods prepared in Example 1, showing lattice fringes with a spacing of 0.37 nm, belonging to the 110 crystal plane of WO3. (d), (e), and (f) are HRTEM images of the catalyst prepared in Example 1, showing lattice fringes belonging to the 111 crystal plane of Pt with a spacing of 0.23 nm.

[0137] The present invention also provides, by way of example, an EDS diagram of the catalyst obtained in Example 1. Figure 9 ),from Figure 9 It can be clearly seen that the active metal element Pt is uniformly dispersed in the form of nanoparticles on the WO3 nanorod support.

[0138] The present invention also provides an exemplary embodiment 1 ( Figure 10 ) and Comparative Example 4 ( Figure 11 XPS graph from Figure 10 It can be clearly seen from the data that the oxygen vacancy content of the catalyst is 16.96%. Figure 10 and Figure 11 It can be seen from this that the platinum in commercial catalysts is mainly Pt and Pt 2+ The Pt in the catalyst prepared in Example 1 is mainly in the form of Pt 2+ It exists in form.

[0139] The present invention also provides exemplary XRD patterns of Embodiment 1 (S1), Embodiment 2 (S2), and Comparative Example 3 (DS3) (e.g. Figure 12 As shown), from Figure 12 It is clear from the data that Example 1 (S1) and Comparative Example 3 (DS3) correspond to the PDF#85-2460 standard card of WO3. However, due to the low platinum content, no obvious diffraction peaks belonging to Pt were observed in Example 1.

[0140] Test Example 1

[0141] The electrocatalytic hydrogen evolution performance of the catalysts provided in the aforementioned examples was tested.

[0142] The above samples were tested using a three-electrode system, with a saturated calomel electrode (SCE) as the reference electrode, a carbon rod electrode as the counter electrode, and 0.5M H2SO4 saturated with H2 as the electrolyte. The tests were conducted using a Shanghai Chenhua CHI 760e electrochemical workstation.

[0143] The working electrode was prepared as follows: 5 mg of the prepared catalyst sample was weighed and dispersed in a mixed solvent of 1 mL ultrapure water and isopropanol (volume ratio 3:1). Then, 20 μL of 5 wt% Nafion membrane solution and 1 mg of carbon black were added as conductive agents. A uniform catalyst dispersion was obtained by ultrasonic dispersion for 30 min at room temperature using an ultrasonic processor. 13.33 μL and 2.5 μL of the above catalyst dispersion were then drop-coated onto a platinum-carbon electrode (d = 5 mm), respectively. After the surface was completely dried, a platinum loading of 10 μg / cm³ was formed. 2 and 1.875 μg / cm 2 The working electrode, reference electrode, and counter electrode were used as a three-electrode system. Linear sweep voltammetry (LSV) and chronoamperometry (it) were performed. The test results are shown in Tables 2 and 3, depending on the platinum loading of the working electrode.

[0144] Table 2

[0145] 10 mA-cm -2 overpotential at the cathode Example 1 9.8 mV Example 2 12.6 mV Example 3 13.2 mV Example 4 20.1 mV Example 5 21.3 mV Example 6 24.6 mV Comparative Example 1 / Comparative Example 2 42.6 mV Comparative Example 3 / Comparative Example 4 25.2 mV Comparative Example 5 /

[0146] Note: In Table 2, " / " indicates 10 μg / cm³ prepared using a catalyst. 2 The platinum-loaded working electrode is at 10 mA·cm -2 The overpotential at the current density is too high, which directly indicates that the catalyst has virtually no electrochemical hydrogen evolution activity.

[0147] As can be seen from the results in Table 2, the hydrogen evolution performance of the catalyst was tested in a three-electrode system at 10 mA·cm⁻¹. -2 The overpotential is used as an indicator to evaluate its electrochemical activity. The catalyst provided by this invention exhibits higher hydrogen evolution activity than the comparative example, at 10 mA·cm⁻¹. -2 The overpotentials were all within 25mV.

[0148] Table 3

[0149]

[0150]

[0151] Note: In Table 3, " / " indicates 1.875 μg / cm³ prepared using a catalyst. 2 The platinum-loaded working electrode is at 10 mA·cm -2 The overpotential at the current density is too high, which directly indicates that the catalyst has virtually no electrochemical hydrogen evolution activity.

[0152] From the results of Table 3, it can be seen that when the platinum loading on the working electrode is reduced to 1.875 pg / cm 2 , the electrochemical activity of the catalyst obtained by the present application has a difference compared with the platinum loading of 10 pg / cm 2 , but still exhibits higher hydrogen evolution activity than the comparative examples. Among them, the difference of the catalyst obtained by Example 1 before and after the reduction of platinum loading is the smallest, and the overpotential of 10 mA·cm -2 is within 15 mV, and it can be calculated that the mass activity of the catalyst obtained by Example 1 at a 50 mV overpotential can reach 14.285 A mg -1 Pt.

[0153] Test Example 2

[0154] A custom-made PEMWE electrolysis cell was used to evaluate the performance of two-electrode water electrolysis.

[0155] The test method is as follows:

[0156] Preparation method of membrane electrode: using the catalyst prepared in the aforementioned Example 1 (S1) and Comparative Example 4 (DS4), catalyst slurry K with a platinum loading of 0.05 mg / cm 2 was prepared, and a commercial IrO2catalyst slurry with an iridium loading of 1.2 mg / cm 2 was also prepared. On both sides of the proton exchange membrane N212, the cathode catalyst slurry K and the commercial IrO2catalyst slurry were sprayed, respectively. The cathode-side gas diffusion layer used hydrophilic carbon paper, and the anode-side gas diffusion layer used commercial platinum-coated titanium felt, thereby obtaining the membrane electrode used for testing.

[0157] The flow battery includes a corrosion-resistant titanium plate (anode bipolar plate) and a graphite plate (cathode bipolar plate) with a single three-snake flow field (area 4.0 cm 2 ) processed thereon; the end plate is made of corrosion-resistant 316 stainless steel (SUS 316), the cathode-side gas diffusion layer uses hydrophilic carbon paper, and the anode-side gas diffusion layer uses commercial platinum-coated titanium felt. The prepared membrane electrode is placed between the anode and cathode bipolar plates, with the cathode catalyst layer facing the hydrophilic carbon paper and the anode catalyst layer facing the platinum-coated titanium felt.

[0158] The electrolysis cell temperature was kept at 60°C, and deionized water was continuously pumped into the anode flow field at a flow rate of 100 sccm by a peristaltic pump. The polarization curve was obtained in cooperation with an electrochemical workstation (Solartron) and a 20A current amplifier. Before the water electrolysis measurement, the prepared MEA was activated by cyclic voltammetry (1.2V-2.0V) until the battery reached the target temperature. The polarization curve of the battery was obtained at a scan rate of 10 mV·s-1. The results are shown in Figure 13 .

[0159] from Figure 13 It can be clearly seen that 40% commercial platinum-carbon (DS4) achieves 1 A·cm at a voltage of 1.95 V. -2 The catalyst (S1) provided by this invention has a platinum loading of 0.05 mg / cm³. 2 At that time, it can reach 1A·cm at a voltage of 1.74V. -2 The current density reaches 2 A·cm at a voltage of 1.94 V. -2 The current density is significantly higher than that exhibited by 40% commercial platinum-carbon catalysts with the same platinum loading. This demonstrates that the catalyst provided by this invention can still exhibit the performance of a platinum-based catalyst with extremely low platinum loading, ensuring high activity of the electrode material while significantly reducing the amount of precious metal platinum, and showing good application prospects in PEMWE devices.

[0160] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for hydrogen production by water electrolysis, characterized in that, The method includes: (1) Sodium tungstate dihydrate aqueous solution is mixed with sulfuric acid to obtain a first solution; the concentration of sodium tungstate dihydrate solution is 30-40 mg / mL; the amount of sulfuric acid used is such that the pH value of the first solution is 1-2; (2) The directing agent is reacted with the first solution, and the resulting product is dried to obtain WO3 nanorods; the mass ratio of sodium tungstate dihydrate to the directing agent is 1:3-4; the reaction conditions include: temperature of 160-190℃ and time of 10-24h; the directing agent is a combination of sulfate and oxalic acid dihydrate with a molar ratio of 3-4:

1. (3) In the presence of water, the platinum source and the WO3 nanorods are mixed for the third time, and the resulting product is dried for the second time to obtain the catalyst precursor; the mass ratio of the platinum source and the WO3 nanorods, respectively, based on the amount of platinum and the amount of WO3 nanorods, is 1:10-40. (4) The catalyst precursor is reduced to obtain the catalyst; the reduction is carried out in the presence of a reducing atmosphere, and the conditions of the reduction are: heating rate of 2-5℃ / min, temperature of 350-450℃, and time of 3-5h. The catalyst contains the active metal element Pt and the supported WO3 nanorods; the active metal element Pt is dispersed in the form of nanoparticles on the supported WO3 nanorods; based on the total mass of the catalyst, the content of Pt is 1-10 wt%. The catalyst has an average diameter of 1-5 nm for Pt nanoparticles and an oxygen vacancy content of 12-20%; the WO3 nanorods have an average length of 100-200 nm and an average diameter of 10-20 nm.

2. The method according to claim 1, characterized in that, Based on the total mass of the catalyst, the Pt content is 3-4 wt%; And / or, the average diameter of the Pt nanoparticles in the catalyst is 1-2 nm, and the oxygen vacancy content of the catalyst is 16.5-17.2%.

3. The method according to claim 1, characterized in that, In step (1), the concentration of the sulfuric acid is 3-5 mol / L; And / or, the conditions for the first mixture include: a temperature of 25-30°C.

4. The method according to claim 1 or 3, characterized in that, In step (2), the sulfate is selected from at least one of ammonium sulfate and sodium sulfate.

5. The method according to claim 4, characterized in that, In step (2), the sulfate is ammonium sulfate.

6. The method according to claim 1 or 3, characterized in that, In step (2), the reaction is carried out in a reaction vessel, and the reaction conditions include: temperature 170-185℃ and time 10-12h.

7. The method according to claim 1 or 3, characterized in that, In step (3), the platinum source is selected from at least one of H2PtCl6·6H2O and potassium chloroplatinate; And / or, the third mixing is carried out under stirring conditions, the conditions of which include: a temperature of 50-90°C and a time of 10-14 hours.

8. The method according to claim 7, characterized in that, In step (3), the platinum source is an aqueous solution of platinum source with a concentration of 10-30 mg / mL.

9. The method according to claim 7, characterized in that, The conditions for the third mixing include a temperature of 60-90°C.

10. The method according to claim 7, characterized in that, The conditions for the third mixing include a time of 11-12 hours.

11. The method according to claim 1 or 3, characterized in that, In step (4), the reducing atmosphere is a combination of hydrogen and argon, and the hydrogen content is 4-6% by volume.

12. A catalyst prepared by the method according to any one of claims 1-11.

13. The application of the catalyst according to claim 12 in the electrolysis of water to produce hydrogen.

14. The application according to claim 13, characterized in that, Application of the catalyst in proton exchange membrane water electrolysis for hydrogen production.

15. The application according to claim 14, characterized in that, Based on the Pt element content, the catalyst loading in the membrane electrode is no higher than 0.05 mg / cm³. 2 .

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