Non-noble metal PEM catalyst prepared through in-situ electrodeposition

Abstract

The invention provides a non-noble metal PEM catalyst prepared through in-situ electrodeposition. The preparation method comprises the following steps: mixing nickel nitrate, cobalt nitrate and an M salt solution, preparing a nickel-cobalt-tungsten precursor loaded on a platinum-plated titanium felt by utilizing an electro-deposition method, and calcining the precursor in an air atmosphere to obtain the nickel-cobalt-tungsten composite material. The nickel element is doped to form the NiCo2O4 catalyst, the valence state of cobalt is regulated and controlled through dissolution of nickel, the reaction activity is improved, and the catalytic performance of the catalyst is improved. According to the invention, high-valence cobalt is used as a raw material, an M element is further doped to form an M-NiCo2O4 catalyst, further transition oxidation and dissolution of high-valence cobalt are inhibited through the M element, and the maintenance of a high-activity state is ensured, so that the acid-resistant stability of the catalyst is improved, and the problem of insufficient stability of the NiCo2O4 catalyst in acidic OER is solved; meanwhile, the doping of the M element can further improve the catalytic performance of the catalyst. The preparation method is simple in process procedure, low in cost and suitable for large-scale preparation.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis, and relates to a non-precious metal PEM catalyst prepared by in-situ electrodeposition, specifically to a self-supported non-precious metal PEM catalyst, a preparation method thereof, and its application in industrial PEM water electrolysis. Background Art

[0002] With the extensive use of fossil energy, the environmental pollution problem is becoming increasingly serious, and energy transformation is imperative. Traditional clean energies such as solar energy and wind energy have the advantages of large total amounts and the limitation of low energy density. Therefore, developing efficient and low-cost energy conversion technologies is the general trend. The water electrolysis method is an ideal and environmentally friendly hydrogen production method.

[0003] Noble metal-based electrocatalysts play a key role in the acidic oxygen evolution reaction (OER) and can promote four-electron / four-proton transitions. However, due to their high cost, it severely restricts their large-scale application in proton exchange membrane water electrolysis (PEMWE). Therefore, researchers have made a great deal of efforts to reduce the use of noble metals in various acidic OER catalysts. Although catalysts using a small amount of noble metals exhibit excellent performance in acidic OER, designing noble metal-free acidic OER catalysts to improve their activity and stability is still a huge challenge.

[0004] Transition metal oxides, as a kind of low-cost catalysts, have good catalytic activity. In particular, Co3O4 is considered an ideal catalyst for acidic water electrolysis. Its structure and composition can effectively enhance its electronic conductivity, thereby increasing its current density and reaction efficiency in OER. At the same time, the surface state and oxidation state of cobalt tetroxide can be adjusted by doping, alloying or other methods, so as to further optimize its catalytic performance. This tunability enables it to exhibit good catalytic performance under different reaction conditions. Therefore, although cobalt tetroxide has certain potential in acidic OER, its structure still needs to be further optimized, its stability improved, and its catalytic performance enhanced in order to achieve better results in practical applications. Summary of the Invention

[0005] The present invention provides a non-precious metal PEM catalyst prepared by in-situ electrodeposition, aiming to overcome the problems of high cost, low activity and instability of catalysts in the existing PEM electrolytic water technology. In the present invention, nickel nitrate, M salt and cobalt nitrate solutions are mixed and used in an electrodeposition method to prepare a nickel-cobalt-tungsten precursor supported on a platinum-plated titanium felt. The precursor is washed and dried, and finally calcined in an air atmosphere to prepare a large-scale self-supporting catalyst. Experimental results show that the self-supporting non-precious metal electrolytic water catalyst prepared by the present invention has high stability and catalytic activity in acidic OER (at room temperature), and the process is simple, with low cost and can be prepared on a large scale, which has good guiding significance for reducing the cost of industrial PEM electrolytic water catalysts. The catalyst of the present invention has excellent catalytic activity and stability in a high current density environment, which can greatly improve the efficiency of catalytic hydrogen production.

[0006] The object of the present invention can be achieved by the following solutions:

[0007] In a first aspect, the present invention provides a preparation method of a non-precious metal PEM catalyst, comprising the following steps:

[0008] S1. Dissolve the M salt and sodium potassium tartrate and heat to obtain a mixed solution 1;

[0009] S2. Dissolve cobalt nitrate, nickel nitrate and sodium citrate and add sodium sulfate. After stirring evenly, add the mixed solution 1 in S1 to obtain a mixed solution 2;

[0010] S3. Perform in-situ electrodeposition in the mixed solution 2 to deposit the metal on the platinum-plated titanium felt to obtain a catalyst precursor (wherein, the counter electrode includes a Pt electrode, the reference electrode includes an Ag / AgCl electrode, and the working electrode is a platinum-plated titanium felt);

[0011] S4. Calcine the dried catalyst precursor (in an air atmosphere), and after ultrasonic treatment and cleaning, it is obtained.

[0012] As an embodiment of the present invention, in step S1, the M element in the M salt includes any one of Cr, Mo, and W; the M salt includes any one of sodium tungstate, potassium tungstate, ammonium tungstate, chromium nitrate, and sodium molybdate.

[0013] As an embodiment of the present invention, in step S1, the heating temperature is 50-60 °C. In some embodiments, a certain amount of M salt and an equal amount of sodium potassium tartrate are ultrasonically dissolved in 10 mL of deionized water, stirred for 5 min, and heated in an oven at 50-60 °C.

[0014] In step S1 of the present invention, due to the large hydrolysis degree of the M salt, the solution will be alkaline, and its hydrolysis ions (such as WO4 2-) has a relatively high reduction potential. Therefore, potassium sodium tartrate is added to enhance the co-deposition ability of W and prevent the hydrolysis of WO4 2- . In addition, adding potassium sodium tartrate can also complex Ni 2+ and Co 2+ , reducing the hydrogen evolution reaction.

[0015] As an embodiment of the present invention, in step S2, the solvent used for dissolution includes deionized water; in 30 - 50 mL of deionized water, the dosage of the M salt is 0.11 - 0.33 mmol, the dosage of potassium sodium tartrate is 0.11 - 0.33 mmol, the dosage of cobalt nitrate is 1 - 2 mmol, the dosage of nickel nitrate is 0.5 - 1 mmol, the dosage of sodium citrate is 2 - 3 mmol, and the dosage of sodium sulfate is 0.03 - 0.05 mol. Preferably, in 30 - 50 mL of deionized water, the dosage of the M salt is 0.33 mmol, the dosage of potassium sodium tartrate is 0.33 mmol, the dosage of cobalt nitrate is 2 mmol, the dosage of nickel nitrate is 1 mmol, the dosage of sodium citrate is 3 mmol, and the dosage of sodium sulfate is 0.05 mol.

[0016] In step S2 of the present invention, sodium citrate is used to complex Co 2+ , Ni 2+ , form stable complexes with Co 2+ and Ni 2+ , inhibiting the generation of precipitation; sodium sulfate is used to improve the conductivity of the solution.

[0017] As an embodiment of the present invention, in step S3, the metals are M, cobalt, and nickel. The present invention deposits the metals in the metal salt onto the platinum - coated titanium felt.

[0018] As an embodiment of the present invention, in step S3, the platinum - coated titanium felt is the treated platinum - coated titanium felt; the treatment method is to soak the platinum - coated titanium felt in concentrated nitric acid and let it stand in the dark.

[0019] As an embodiment of the present invention, in step S3, the potential used for the working electrode is a constant potential of - 1.0 V, and the working time is 1 - 3 h. The in - situ electrodeposition of the present invention uses a three - electrode system.

[0020] As an embodiment of the present invention, in step S3, the catalyst precursor is alternately rinsed several times with water and absolute ethanol and then dried in an oven to remove moisture. The number of rinsing times is more than 3 times, and it is dried in the oven at 60 °C for 8 h.

[0021] As an embodiment of the present invention, in step S4, the calcination temperature is 350 - 450 °C, the heating rate is 4 - 6 °C / min, and the heat preservation time is 3 - 4 h. In some embodiments, the calcination is carried out in a muffle furnace.

[0022] As an embodiment of the present invention, in step S4, the power of the ultrasonic treatment is 70 - 100 Hz, and the time is 5 - 10 seconds; the cleaning is carried out by repeatedly rinsing with ethanol and deionized water to remove any loosely connected particles.

[0023] In a second aspect, the present invention provides a non - noble metal PEM catalyst prepared by the above - mentioned preparation method. The general formula of the non - noble metal PEM catalyst is M - NiCo2O4; wherein, M is three elements (Cr, Mo, W) of the sixth subgroup.

[0024] Furthermore, the non - noble metal PEM catalyst is a tungsten - nickel co - doped cobalt tetroxide self - supported catalyst, and the molar ratio of the tungsten - nickel co - doped cobalt tetroxide is 1:3:6, having uniform element dispersion and a regular structure.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. Based on the requirements of acidic electrolyzed water, the non - noble metal PEM catalyst of the present invention has a main body of entropy oxide composed of transition metals. Utilizing the unique properties of cobalt tetroxide, by doping nickel element (forming NiCo2O4 catalyst), the valence state of cobalt is regulated by the dissolution of nickel, enhancing the reaction activity and improving the catalytic performance of the catalyst; further, by co - electrodepositing cobalt salt and nickel salt, depositing the metal on the platinum - plated titanium felt, the catalytic area of the co - doped oxide is greatly increased, further improving the catalytic performance; at the same time, the platinum - plated titanium felt as the carrier of the catalyst can also enhance the stability, conductivity and metal interface effect of the catalytic material.

[0027] 2. The present invention first discovers the problem of insufficient stability of the NiCo2O4 catalyst in acidic OER, and further dopes three transition metals (Cr, Mo, W) of the sixth subgroup in NiCo2O4 to synthesize M - NiCo2O4. During the OER process, M - NiCo2O4 plays a stabilizing role by doping metal M, that is, by inhibiting the further over - oxidation and dissolution of high - valence cobalt, ensuring the maintenance of the high - activity state, thereby improving the stability of the catalyst in acidic OER. In addition, the doping of the sixth - subgroup metal element M can further enhance the catalytic performance of the catalyst.

[0028] 3. The present invention provides a preparation process for a self-supporting non-precious metal PEM catalyst, which is mainly based on electro-deposition to partially deposit metal ions in a solution, enabling the metal to be loaded on a platinum-plated titanium felt, thereby forming an electrocatalyst with high stability, high catalytic activity, and high specific surface area. The preparation process of the present invention is a general synthetic strategy for transition metal catalysts, providing a new idea for the large-scale preparation of transition metal catalysts; at the same time, the above process has the advantages of strong stability, simple operation, low cost, and large-scale preparation, and has great industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] By reading the following detailed description of the non-limiting embodiments with reference to the accompanying drawings, other features, objects, and advantages of the present invention will become more apparent:

[0030] Figure 1 SEM diagram of W-NiCo2O4 in Example 1;

[0031] Figure 2 XRD comparison diagram of the catalysts prepared in Example 1 and Comparative Example 3;

[0032] Figure 3 LSV curves of the catalysts prepared in Examples 1-3 and Comparative Examples 2-3;

[0033] Figure 4 LSV curves of carbon paper supported W-NiCo2O4 in Comparative Example 1 and platinum-plated titanium felt supported W-NiCo2O4 in Example 1;

[0034] Figure 5 Stability diagrams of the catalysts prepared in Example 1 and Comparative Examples 2-3 in 0.5M H2SO4 solution at 10mA cm -1 and 100mA cm -1 ;

[0035] Figure 6 Stability diagrams of the catalysts prepared in Examples 2-3 and Comparative Example 1 in 0.5M H2SO4 solution at 10mA cm -1 ; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following examples are implemented on the premise of the technical solution of the present invention, providing detailed implementation manners and specific operation processes, which will help those skilled in the art to further understand the present invention. It should be noted that the protection scope of the present invention is not limited to the following embodiments. Any adjustments and improvements made on the premise of the concept of the present invention belong to the protection scope of the present invention.

[0037] Example 1

[0038] The self-supported non-precious metal PEM catalyst W-NiCo2O4 of this example is prepared by a method including the following steps:

[0039] Step (1): Prepare the solution. Dissolve 0.33 mmol of sodium tungstate and 0.33 mmol of potassium sodium tartrate in 10 m of deionized water, stir evenly, and heat in an oven at 50 °C to form a homogeneous solution. Dissolve 2 mmol of cobalt nitrate, 1 mmol of nickel nitrate, 3 mmol of sodium citrate dihydrate, and 0.05 mol of sodium sulfate in 30 mL of deionized water and stir until a homogeneous solution is formed. Mix the two solutions and stir magnetically for 5 minutes.

[0040] Step (2): Prepare the precursor. Deposit three metal salts (Ni, Co, W) on the treated platinum-plated titanium felt by the three-electrode electrodeposition method for the solution in step (1) (the treatment method is to soak the platinum-plated titanium felt in concentrated nitric acid and let it stand in the dark for 12 h). The counter electrode is a Pt electrode, the reference electrode is an Ag / AgCl electrode, and the working electrode is the platinum-plated titanium felt. The electroplating voltage is -1 V and the time is 1 h. Alternately rinse the catalyst precursor deposited on the platinum-plated titanium felt several times with water and absolute ethanol, and then dry it in an oven at 60 °C for 8 h to remove moisture.

[0041] Step (3): High-temperature treatment. Calcinate the sample obtained in step (2) in an air atmosphere. The calcination temperature of the precursor in the muffle furnace is 350 °C, the heating rate of the muffle furnace is 4 °C / min, the holding time is 3 h, and then cool to room temperature. Ultrasonically treat the obtained product for 10 seconds to remove any loosely connected particles, and repeatedly rinse it with ethanol and deionized water more than 3 times. It can be Figure 1 seen that the synthesized catalyst presents a two-dimensional sheet structure and has a large specific surface area, exposing more active sites.

[0042] Step (4): Test the OER performance of the synthesized W-NiCo2O4 catalyst. The test system is a three-electrode system. The counter electrode is a platinum wire and the reference electrode is a silver chloride electrode. From Figure 3 the LSV curve (corresponding to the W-NiCo2O4 curve), it can be seen that its overpotential at a current density of 10 mA cm -2 is only 274 mV; from Figure 5 it can be seen that it can be stable for more than 600 h at a current density of 10 mA cm -2 , and it can be stable for more than 300 h at a current density of 100 mA cm -2 .

[0043] Example 2

[0044] The self-supporting non-noble metal PEM catalyst Cr-NiCo2O4 of this example is prepared by a method comprising the following steps:

[0045] Step (1): Prepare the solution. Dissolve 0.33 mmol of chromium nitrate and 0.33 mmol of potassium sodium tartrate in 10 mL of deionized water, stir evenly, and heat in an oven at 50 °C to form a homogeneous solution. Dissolve 2 mmol of cobalt nitrate, 1 mmol of nickel nitrate, 3 mmol of sodium citrate dihydrate, and 0.05 mol of sodium sulfate in 30 mL of deionized water and stir until a homogeneous solution is formed. Mix the two solutions and stir magnetically for 5 minutes.

[0046] Step (2): Prepare the precursor. Deposit three metal salts (Ni, Co, Cr) on the treated platinum-plated titanium felt by three-electrode electrodeposition method for the solution in step (1) (the treatment method is to soak the platinum-plated titanium felt in concentrated nitric acid and let it stand in the dark for 12 h). The counter electrode is a Pt electrode, the reference electrode is Ag / AgCl, the working electrode is the platinum-plated titanium felt, the electroplating voltage is -1V, and the time is 1 h. Alternately rinse the catalyst precursor deposited on the platinum-plated titanium felt several times with water and absolute ethanol, and then dry it in an oven at 60 °C for 8 h to remove moisture.

[0047] Step (3): High-temperature treatment. Calcinate the sample obtained in step (2) in an air atmosphere. The calcination temperature of the precursor in the muffle furnace is 350 °C, the heating rate of the muffle furnace is 4 °C / min, the holding time is 3 h, and then cool to room temperature. Ultrasonically treat the obtained product for 10 seconds to remove any loosely connected particles, and repeatedly rinse it with ethanol and deionized water more than 3 times.

[0048] Step (4): Test the OER performance of the synthesized Cr-NiCo2O4 catalyst. From Figure 3 the LSV curve (corresponding to the Cr-NiCo2O4 curve), it can be seen that its overpotential is 400 mV at a current density of 10 mA cm -2 ; From Figure 6 it can be seen that it can be stable for 100 h at a current density of 10 mA cm -2 .

[0049] Example 3

[0050] The self-supporting non-noble metal PEM catalyst Mo-NiCo2O4 of this example is prepared by a method comprising the following steps:

[0051] Step (1): Prepare the solution. Dissolve 0.33 mmol of sodium molybdate and 0.33 mmol of sodium potassium tartrate in 10 mL of deionized water, stir evenly, and then heat in an oven at 50 °C to form a homogeneous solution. Dissolve 2 mmol of cobalt nitrate, 1 mmol of nickel nitrate, 3 mmol of trisodium citrate dihydrate, and 0.05 mol of sodium sulfate in 30 mL of deionized water and stir until a homogeneous solution is formed. Mix the two solutions and stir magnetically for 5 minutes.

[0052] Step (2): Prepare the precursor. Deposit three metal salts (Ni, Co, Mo) on the treated platinum-plated titanium felt by three-electrode electrodeposition using the solution in step (1) (the treatment method is to soak the platinum-plated titanium felt in concentrated nitric acid and let it stand in the dark for 12 h). The counter electrode is a Pt electrode, the reference electrode is Ag / AgCl, and the working electrode is the platinum-plated titanium felt. The electroplating voltage is -1 V and the time is 1 h. Alternately rinse the catalyst precursor deposited on the platinum-plated titanium felt several times with water and absolute ethanol, and then dry it in an oven at 60 °C for 8 h to remove the moisture.

[0053] Step (3): High-temperature treatment. Calcinate the sample obtained in step (2) at high temperature in an air atmosphere. The calcination temperature of the precursor in the muffle furnace is 350 °C, the heating rate of the muffle furnace is 4 °C / min, the holding time is 3 h, and then cool to room temperature. Ultrasonically treat the obtained product for 10 s to remove any loosely connected particles, and repeatedly rinse it with ethanol and deionized water more than 3 times.

[0054] Step (4): Test the OER performance of the synthesized Mo-NiCo2O4 catalyst. From Figure 3 the LSV curve (corresponding to the Mo-NiCo2O4 curve), it can be seen that its overpotential is 347 mV at a current density of 10 mA cm -2 . From Figure 6 it can be seen that it can be stable for 200 h at a current density of 10 mA cm -2 .

[0055] Comparative Example 1

[0056] The preparation method of this comparative example is basically the same as that of Example 1, except that the platinum-plated titanium felt is replaced with carbon paper, and it is prepared by the method including the following steps:

[0057] Step (1): Prepare the solution. Dissolve 0.33 mmol of sodium tungstate and 0.33 mmol of sodium potassium tartrate in 10 mL of deionized water, stir evenly, and then heat in an oven at 50 °C to form a homogeneous solution. Dissolve 2 mmol of cobalt nitrate, 1 mmol of nickel nitrate, 3 mmol of trisodium citrate dihydrate, and 0.05 mol of sodium sulfate in 30 mL of deionized water and stir until a homogeneous solution is formed. Mix the two solutions and stir magnetically for 5 minutes.

[0058] Step (2): Prepare the precursor. Deposit three metal salts (Ni, Co, W) on the treated carbon paper by three-electrode electrodeposition using the solution in step (1) (the treatment method is to soak the carbon paper in concentrated nitric acid and let it stand in the dark for 12 h). The counter electrode is a Pt electrode, the reference electrode is Ag / AgCl, and the working electrode is the carbon paper. The electroplating voltage is -1 V and the time is 1 h. After the catalyst precursor deposited on the platinum-coated titanium felt is rinsed alternately with water and absolute ethanol several times, it is dried in an oven at 60 °C for 8 h to remove moisture.

[0059] Step (3): High-temperature treatment. Calcinate the sample obtained in step (2) at high temperature in an air atmosphere. The calcination temperature of the precursor in the muffle furnace is 350 °C, the heating rate of the muffle furnace is 4 °C / min, the holding time is 3 h, and it is cooled to room temperature. The obtained product is ultrasonically treated for 10 seconds to remove any loosely connected particles, and is repeatedly rinsed with ethanol and deionized water more than 3 times.

[0060] Step (4): Test the OER performance of the carbon paper-supported W-NiCo2O4 catalyst. From Figure 4 the LSV curve in, its overpotential is 330 mV at a current density of 10 mA cm -2 ; from Figure 6 it can be seen that it can be stable for 400 h at a current density of 10 mA cm -2 .

[0061] Comparative Example 2

[0062] The preparation method of this comparative example is basically the same as that of Example 1, except that sodium tungstate is not added, and it is prepared by a method including the following steps:

[0063] Step (1): Dissolve 2 mmol of cobalt nitrate, 1 mmol of nickel nitrate, 3 mmol of sodium citrate dihydrate, 0.33 mmol of potassium sodium tartrate, and 0.05 mol of sodium sulfate in 40 mL of deionized water and stir until a homogeneous solution is formed. After mixing the two solutions, stir magnetically for 5 minutes.

[0064] Step (2): Prepare the precursor. Deposit two metal salts on the treated platinum-coated titanium felt by three-electrode electrodeposition using the solution in step (1) (the treatment method is to soak the platinum-coated titanium felt in concentrated nitric acid and let it stand in the dark for 12 h). The counter electrode is a Pt electrode, the reference electrode is an Ag / AgCl electrode, the working electrode is the platinum-coated titanium felt, the electroplating voltage is -1 V, and the time is 1 h. After the catalyst precursor deposited on the platinum-coated titanium felt is rinsed alternately with water and absolute ethanol several times, it is dried in an oven at 60 °C for 8 h to remove moisture.

[0065] Step (3): High-temperature treatment. The sample obtained in step (2) is calcined at high temperature in an air atmosphere. The calcination temperature of the precursor in the muffle furnace is 350 °C, the heating rate of the muffle furnace is 4 °C / min, the holding time is 3 h, and it is cooled to room temperature. The obtained product is ultrasonically treated for 10 seconds to remove any loosely connected particles, and rinsed repeatedly with ethanol and deionized water more than 3 times.

[0066] Step (4): Test the OER performance of the synthesized NiCo2O4 catalyst. The test system is a three-electrode system. The counter electrode is a platinum wire, and the reference electrode is a silver chloride electrode. And compare with the performance of Example 1. From Figure 3 the LSV curve (corresponding to the NiCo2O4 curve), it can be seen that its overpotential is 320 mV at a current density of 10 mA cm -2 ; from Figure 5 it can be seen that it can be stable for 300 h at a current density of 10 mA cm -2 , and can be stable for 100 h at a current density of 100 mA cm -2 .

[0067] Comparative Example 3

[0068] The preparation method of this comparative example is basically the same as that of Example 1, except that sodium tungstate and nickel nitrate are not added, and it is prepared by a method including the following steps:

[0069] Step (1): Dissolve 2 mmol of cobalt nitrate, 3 mmol of sodium citrate dihydrate, 0.33 mmol of sodium potassium tartrate, and 0.05 mol of sodium sulfate in 40 mL of deionized water and stir until a homogeneous solution is formed. After mixing the two solutions, magnetically stir for 5 minutes.

[0070] Step (2): Prepare the precursor. The solution in step (1) is used to deposit metal salts on the treated platinum-plated titanium felt by three-electrode electrodeposition (the treatment method is to soak the platinum-plated titanium felt in concentrated nitric acid and let it stand in the dark for 12 h). The counter electrode is a Pt electrode, the reference electrode is an Ag / AgCl electrode, the working electrode is the platinum-plated titanium felt, the electroplating voltage is -1 V, and the time is 1 h. The catalyst precursor deposited on the platinum-plated titanium felt is alternately rinsed several times with water and absolute ethanol and then dried in an oven at 60 °C for 8 h to remove moisture.

[0071] Step (3): High-temperature treatment. The sample obtained in step (2) is calcined at high temperature in an air atmosphere. The calcination temperature of the precursor in the muffle furnace is 350 °C, the heating rate of the muffle furnace is 4 °C / min, the holding time is 3 h, and it is cooled to room temperature. The obtained product is ultrasonically treated for 10 seconds to remove any loosely connected particles, and rinsed repeatedly with ethanol and deionized water more than 3 times. From Figure 2It can be seen that the W, Ni co-doped Co3O4 synthesized in Example 1 has the same crystal structure as pure Co3O4, which is a typical spinel phase.

[0072] Step (4): Test the OER performance of the synthesized Co3O4 catalyst and compare it with the performance of Example 1. From Figure 3 the LSV curve (corresponding to the Co3O4 curve), it can be seen that its overpotential is 425 mV at a current density of 10 mA cm -2 ; from Figure 5 it can be seen that it can only be stable for 20 h at a current density of 10 mA cm -2 , and only be stable for 10 h at a current density of 100 mA cm -2 .

[0073] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A preparation method of a non-noble metal PEM catalyst, characterized in that, It includes the following steps: S1. Dissolve M salt and sodium potassium tartrate and heat to obtain mixture 1; the M element in the M salt includes any one of Cr, Mo, and W. S2. Dissolve cobalt nitrate, nickel nitrate, and sodium citrate, add sodium sulfate, stir evenly, and then add mixture 1 in S1 to obtain mixture 2. S3. Perform in-situ electrodeposition in mixture 2 to deposit metal onto the platinum-coated titanium felt to obtain the catalyst precursor. S4. Calcinate the dried catalyst precursor, perform ultrasonic treatment and cleaning to obtain the product.

2. The preparation method according to claim 1, characterized in that, In step S1, the M salt includes any one of sodium tungstate, potassium tungstate, ammonium tungstate, chromium nitrate, and sodium molybdate.

3. The preparation method according to claim 1, characterized in that, In step S1, the heating temperature is 50 - 60°C.

4. The preparation method according to claim 1, characterized in that, In step S2, the solvent used for dissolution includes deionized water; in 30 - 50 mL of deionized water, the dosage of the M salt is 0.11 - 0.33 mmol, the dosage of sodium potassium tartrate is 0.11 - 0.33 mmol, the dosage of cobalt nitrate is 1 - 2 mmol, the dosage of nickel nitrate is 0.5 - 1 mmol, the dosage of sodium citrate is 2 - 3 mmol, and the dosage of sodium sulfate is 0.03 - 0.05 mol.

5. The preparation method according to claim 1, wherein In step S3, the metal is M, cobalt, and nickel.

6. The preparation method according to claim 1, characterized in that, In step S3, the platinum-coated titanium felt is the treated platinum-coated titanium felt; the treatment method is to soak the platinum-coated titanium felt in concentrated nitric acid and let it stand in the dark.

7. The preparation method according to claim 1, wherein In step S3, the potential used for the working electrode is a constant potential of -1.0 V, and the working time is 1 - 3 h.

8. The preparation method according to claim 1, characterized in that, In step S4, the calcination temperature is 350 - 450°C, the heating rate is 4 - 6°C / min, and the heat preservation time is 3 - 4 h.

9. The preparation method according to claim 1, characterized in that, In step S4, the power of ultrasonic treatment is 70 - 100 Hz, and the time is 5 - 10 seconds; the cleaning is performed by repeatedly rinsing with ethanol and deionized water.

10. A non-noble metal PEM catalyst obtained by the preparation method according to any one of claims 1-9, characterized in that, The general formula of the non-noble metal PEM catalyst is M-NiCo2O4; where M is Cr, Mo, or W.

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