Preparation method of multi-metal phosphide heterojunction electrode for oxygen evolution reaction

Abstract

The invention discloses a preparation method of a multi-metal phosphide heterojunction electrode for an oxygen evolution reaction, which comprises the following steps of: depositing a uniform multi-metal phosphide component active coating on a conductive substrate by adopting a plurality of non-noble metal salts as precursors through an electrochemical reduction method, and combining a plurality of metal phosphides to form a phosphide heterojunction structure, so as to obtain the multi-metal phosphide heterojunction electrode for the oxygen evolution reaction. And the self-supporting electrode material is tightly combined with the conductive substrate. The electrode material disclosed by the invention has the advantages of universality, simplicity in operation and controllable components, and shows excellent catalytic activity and wide application prospect in a reaction of oxygen evolution by electrolysis of water.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalytic materials, and relates to a preparation method of a multimetal phosphide heterojunction electrode for an oxygen evolution reaction. BACKGROUND

[0002] Hydrogen (H2) is widely used in aerospace, medical, chemical, energy and other fields as a clean, efficient and environmentally friendly energy source. Electrolysis of water is considered as one of the most promising green hydrogen production technologies. However, the oxygen evolution reaction (OER) at the anode usually affects the entire process of water electrolysis due to slow kinetics. Currently, commercial anode catalysts mainly include iridium, ruthenium and their oxides. However, the high cost and low reserves of noble metal catalysts greatly limit their large-scale application. Therefore, it is urgent to develop efficient, durable and low-cost non-noble metal electrocatalysts for OER to achieve efficient electrolysis of water to produce hydrogen. SUMMARY

[0003] To improve the above technical problems, the present application provides a preparation method of an electrode, which comprises the following steps: A transition metal salt, a rare earth metal salt and a phosphorus source are mixed as an electrolyte to obtain an electroplating solution. An electrically conductive substrate is used as a negative electrode, and a metal material is used as a positive electrode. A multimetal phosphide is deposited on the negative electrode substrate by an electrochemical reduction method to obtain the electrode.

[0004] According to an embodiment of the present application, the preparation method further comprises taking out the negative electrode after the electroplating is stopped, and cleaning and drying to obtain the electrode material.

[0005] According to an embodiment of the present application, the metal elements in the transition metal salt at least include iron and molybdenum.

[0006] In some embodiments, the metal elements in the transition metal salt can further include one, two or more of manganese, cobalt, nickel, copper and zinc. Exemplarily, the transition metal salt is one, two or more of ferric nitrate and its hydrate, sodium molybdate, cobalt nitrate hexahydrate and nickel chloride.

[0007] In one embodiment of the present application, the transition metal salt is a mixture of ferric nitrate and its hydrate and sodium molybdate, and the molar ratio of the ferric nitrate and its hydrate to the sodium molybdate is 1: (0.5-2), for example 1:1.

[0008] In one embodiment of the present application, the transition metal salt is a mixture of ferric nitrate and its hydrate, cobalt nitrate hexahydrate and sodium molybdate, and the molar ratio of the ferric nitrate and its hydrate, the cobalt nitrate hexahydrate to the sodium molybdate is 1: (0.5-2): (0.5-2), for example 1:1:1.

[0009] According to an embodiment of the present application, the molar ratio of the rare earth metal salt to the transition metal salt is 1: (5-100), for example, 1:8, 1:12, 1:20, 1:40, or 1:80.

[0010] According to an embodiment of the present application, the molar ratio of the transition metal salt to the phosphorus source is 1: (0.5-2), for example, 1:1, 1:1.5, or 1:2.

[0011] According to an embodiment of the present application, the plating solution further contains sodium citrate. Preferably, the molar ratio of the transition metal salt to sodium citrate is 1: (0.05-0.2), for example, 1:0.1, 1:0.15, or 1:0.2.

[0012] According to an embodiment of the present application, the rare earth element in the rare earth metal salt is at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, and gadolinium; and preferably, the rare earth metal salt is at least one of a nitrate of the rare earth element, a sulfate of the rare earth element, an acetate of the rare earth element, a chloride of the rare earth metal, a carbonyl salt of the rare earth metal, and a molybdate of the rare earth metal.

[0013] Illustratively, the rare earth metal salt is cerium nitrate hexahydrate, lanthanum nitrate hexahydrate, samarium nitrate hexahydrate, or praseodymium nitrate hexahydrate.

[0014] According to an embodiment of the present application, the phosphorus source is at least one of phosphoric acid, sodium phosphate, sodium hypophosphite monohydrate, potassium phosphate, and potassium hypophosphite.

[0015] According to an embodiment of the present application, the total molar concentration of the metal elements in the plating solution is 0.01-2 mol / L, for example, 0.01 mol / L, 0.1 mol / L, 0.45 mol / L, 1 mol / L, or 2 mol / L. -1 -1 -1 -1 -1 -1

[0016] According to an embodiment of the present application, the molar concentration of the phosphorus element in the plating solution is 0.001-1 mol / L, for example, 0.01 mol / L, 0.1 mol / L, 0.5 mol / L, 0.6 mol / L, 1 mol / L, or 2 mol / L. -1 -1 -1 -1 -1 -1 -1

[0017] ​​​​​​​​​​​​​According to an embodiment of the present application, the conductive substrate is selected from at least one of titanium felt, carbon felt, nickel mesh, nickel foam, carbon paper and carbon cloth.

[0018] According to an embodiment of the present application, the metal material is selected from at least one of manganese, iron, cobalt, nickel, copper, zinc and molybdenum.

[0019] In one embodiment of the present application, the metal material is selected from molybdenum sheet or nickel foam.

[0020] According to an embodiment of the present application, the electrochemical reduction method is performed under constant current. Preferably, the constant current is applied by an external power source. Preferably, the current density is 0.1-1000 mA cm -2 , for example 200 mA cm -2 , 300 mA cm -2 or 400 mA cm -2 ; and the current-on time is 1-600 minutes, for example 10 min, 20 min, 30 min, 40 min.

[0021] According to an embodiment of the present application, the deposition temperature is room temperature-60℃, for example 30℃, 40℃ or 50℃.

[0022] The present application also provides an electrode prepared by the above preparation method.

[0023] According to an embodiment of the present application, the electrode comprises a conductive substrate and a multi-metal phosphide heterojunction plating layer loaded on the surface of the conductive substrate. The multi-metal phosphide heterojunction is uniform and structurally stable on the surface of the conductive substrate.

[0024] According to an embodiment of the present application, the conductive substrate is selected from at least one of titanium felt, carbon felt, nickel mesh, nickel foam, carbon paper and carbon cloth.

[0025] The present application also provides the above electrode for use in the anode oxygen evolution reaction of an electrocatalytic water splitting hydrogen production system.

[0026] The present application also provides an electrolysis system with the above electrode as a working electrode.

[0027] The present application has the following advantages: 1. The present application uses a plurality of non-noble metal salts as precursors, and through an electrochemical reduction method, a uniform multi-metal phosphide component active plating layer is deposited on a conductive substrate, wherein the plurality of metal phosphides combine to form a phosphide heterojunction structure, which is tightly combined with the conductive substrate to form a self-supporting electrode material. The preparation method of the present application can prepare a multi-metal phosphide heterojunction electrode material, and this method has wide applicability, easy control of conditions, easy operation, simple electrode preparation process and low cost.

[0028] 2. The elemental composition, content, and ratio of the polymetallic phosphide heterojunction prepared by this invention are easily adjustable, and the coating structure morphology is controllable. Therefore, it can be adjusted according to different requirements of the catalytic reaction.

[0029] 3. The polymetallic phosphide heterojunction electrode prepared by the present invention exhibits superior catalytic performance and structural stability in the electrocatalytic water splitting oxygen evolution system, and therefore has potential application prospects in the field of water splitting oxygen evolution. Attached Figure Description

[0030] Figure 1 The image shows the scanning electron microscope (SEM) morphology of the rare earth-doped electrode material prepared in Example 6 and the original nickel foam conductive substrate.

[0031] Figure 2 The image shows a comparison of the XRD structures of the rare earth-doped electrode material prepared in Example 6, the electrode material prepared in Comparative Example 2, and the original nickel foam conductive substrate.

[0032] Figure 3 The image shows the EDX elemental distribution of the rare earth-doped electrode material prepared in Example 6.

[0033] Figure 4 This is a comparison chart of the oxygen generation performance of electrode materials prepared from commercial iridium oxide in Example 6, Comparative Example 1, Comparative Example 2, and Example 2.

[0034] Figure 5 The graph shows a comparison of the oxygen generation performance of the rare earth-doped electrode materials prepared in Examples 4-6.

[0035] Figure 6 The diagram shows a comparison of oxygen production in the rare earth-doped electrode materials prepared in Examples 6 and 11-13. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0037] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0038] The electrode materials of Examples 1-13 of the present invention were tested using the following instruments and methods: The morphology of the electrode materials of Examples 1-13 was characterized by scanning electron microscopy (SEM), and the structure of the electrode materials prepared in the examples was characterized by X-ray diffraction (XRD). The oxygen production performance of the electrode materials in Examples 1-13 was determined in an electrocatalytic water splitting system.

[0039] Example 1 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate hexahydrate, 0.02 mol sodium molybdate, 0.005 mol samarium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. A nickel foam (1 cm x 1 cm, 1 mm thick) was used as the negative electrode conductive substrate, and a molybdenum sheet was used as the positive electrode (sacrificial anode). An external power supply was connected to construct the electroplating apparatus.

[0040] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and then subjected to electroplating at 50 ℃. o After drying at C for 6 hours, a multi-metal phosphide heterojunction electrode material is obtained.

[0041] Example 2 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate hexahydrate, 0.02 mol sodium molybdate, 0.005 mol lanthanum nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. Nickel foam (1 cm in size) was then used. A 1cm thick molybdenum sheet (1 mm thick) serves as the negative electrode conductive substrate, while a molybdenum sheet acts as the sacrificial anode. An external power supply is then used to construct the electroplating device.

[0042] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and then subjected to electroplating at 50 ℃. o After drying at C for 6 hours, a multi-metal phosphide heterojunction electrode material is obtained.

[0043] Example 3 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate, 0.02 mol sodium molybdate, 0.005 mol cerium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. Nickel foam (1 cm in size) was then used. A 1cm thick molybdenum sheet (1 mm thick) serves as the negative electrode conductive substrate, while a molybdenum sheet acts as the sacrificial anode. An external power supply is then used to construct the electroplating device.

[0044] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0045] Example 4 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.002 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. A nickel foam (1 cm x 1 cm, 1 mm thick) was used as the negative electrode conductive substrate, and a molybdenum sheet was used as the sacrificial anode. An external power supply was connected to construct the electroplating apparatus.

[0046] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0047] Example 5 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.0005 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. A nickel foam (1 cm x 1 cm, 1 mm thick) was used as the negative electrode conductive substrate, and a molybdenum sheet was used as the sacrificial anode. An external power supply was connected to construct the electroplating apparatus.

[0048] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0049] Example 6 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.001 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. A nickel foam (1 cm x 1 cm, 1 mm thick) was used as the negative electrode conductive substrate, and a molybdenum sheet was used as the sacrificial anode. An external power supply was connected to construct the electroplating apparatus.

[0050] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 °C for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 °C for 6 hours to obtain the multi-metal phosphide heterojunction electrode material. A scanning electron microscope image of the electrode loaded with the electrode material of this embodiment is shown below. Figure 1 As shown, compared to the original smooth nickel foam conductive substrate, the electrode surface prepared in this embodiment has a more uniform electroplated layer. The structural characterization of the electroplated layer is as follows. Figure 2 As shown, the XRD results indicate that the electrode body is a nickel conductive substrate, and changes in the composition and content of the plating solution did not cause significant changes in the XRD peak values.

[0051] The elemental distribution in the multimetallic phosphide heterojunction electrode material obtained in this embodiment is as follows: Figure 3 As shown, the results indicate that the elements nickel, iron, molybdenum, praseodymium, and phosphorus are uniformly distributed, thus confirming the successful preparation of the electrode material.

[0052] The above Examples 1-6 all demonstrate that corresponding anode electrode materials can be prepared by changing the types and concentrations of rare earth element nitrates and transition metal salts in the plating solution. This indicates that the preparation method of the present invention can realize the synthesis of polymetallic phosphide electrode materials.

[0053] Example 7 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.001 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. An electroplating apparatus was constructed using carbon paper (1 cm x 1 cm, 0.2 mm thick) as the negative conductive substrate and a molybdenum sheet as the sacrificial anode, connected to an external power supply.

[0054] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0055] Example 8 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.001 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. An electroplating apparatus was constructed using nickel foam (1 cm x 1 cm, 1 mm thick) as the negative conductive substrate and nickel foam as the sacrificial anode, connected to an external power supply.

[0056] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0057] Example 9 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.001 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. An electroplating apparatus was constructed using carbon paper (1 cm x 1 cm, 0.2 mm thick) as the negative conductive substrate and nickel foam as the sacrificial anode, connected to an external power supply.

[0058] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0059] The above embodiments 7-9 can all prepare multi-metal phosphide heterojunction electrode materials by changing the type of conductive substrate of the negative electrode and the sacrificial electrode material of the positive electrode during the electroplating process.

[0060] Example 10 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.001 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. An electroplating apparatus was constructed using nickel foam (1 cm x 1 cm, 1 mm thick) as the negative conductive substrate and a molybdenum sheet as the sacrificial anode, connected to an external power supply.

[0061] 2. At a current density of 300 mA cm⁻¹ -2Electroplating was performed continuously at 50 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0062] Example 11 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.001 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. An electroplating apparatus was constructed using nickel foam (1 cm x 1 cm, 1 mm thick) as the negative conductive substrate and a molybdenum sheet as the sacrificial anode, connected to an external power supply.

[0063] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 10 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0064] Example 12 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.001 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. An electroplating apparatus was constructed using nickel foam (1 cm x 1 cm, 1 mm thick) as the negative conductive substrate and a molybdenum sheet as the sacrificial anode, connected to an external power supply.

[0065] 2. At a current density of 200 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 30 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0066] Example 13 The preparation method of polymetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol ferric nitrate nonahydrate, 0.02 mol sodium molybdate, 0.001 mol praseodymium nitrate hexahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. An electroplating apparatus was constructed using nickel foam (1 cm x 1 cm, 1 mm thick) as the negative conductive substrate and a molybdenum sheet as the sacrificial anode, connected to an external power supply.

[0067] 2. At a current density of 400 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the multi-metal phosphide heterojunction electrode material.

[0068] The corresponding electrode materials can be prepared by changing the current density, electroplating time and temperature in the above embodiments 10-13.

[0069] Comparative Example 1 The preparation method of single-metal phosphide electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol sodium molybdate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. An electroplating apparatus was constructed using nickel foam (1 cm x 1 cm, 1 mm thick) as the negative conductive substrate and a molybdenum sheet as the sacrificial anode, connected to an external power supply.

[0070] 2. At a current density of 300 mA cm⁻¹ -2 Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the monometallic phosphide electrode material.

[0071] Comparative Example 2 The preparation method of bimetallic phosphide heterojunction electrode material includes the following steps: 1. An electroplating solution was prepared by ultrasonically dissolving 0.02 mol sodium molybdate, 0.02 mol ferric nitrate nonahydrate, 0.06 mol sodium hypophosphite, and 0.006 mol sodium citrate in 100 mL of ultrapure water. An electroplating apparatus was constructed using nickel foam (1 cm x 1 cm, 1 mm thick) as the negative conductive substrate and a molybdenum sheet as the sacrificial anode, connected to an external power supply.

[0072] 2. At a current density of 300 mA cm⁻¹ -2Electroplating was performed continuously at 30 ℃ for 40 min. After electroplating was stopped, the negative electrode material was removed, cleaned, and dried at 50 ℃ for 6 hours to obtain the bimetallic phosphide heterojunction electrode material.

[0073] Application Example 1 Using the electrode materials obtained in Example 6 and Comparative Examples 1 and 2 as anolyte catalysts in the water electrolysis system, the potential of the prepared polymetallic phosphide electrode material for electrolytic oxygen desorption is demonstrated: 1. Test System Setup: The test apparatus was a three-electrode system. The reference electrode was Hg / HgO (1 M KOH solution), the counter electrode was a carbon rod, and the working electrodes were the electrode materials of Example 6 and Comparative Examples 1 and 2, respectively. The electrolyte was a 1 M KOH solution. A 50 mL double-layer single-cell electrolytic cell was used during the test.

[0074] 2. Catalytic performance evaluation method: The electrolytic cell temperature is maintained at room temperature, and the oxygen evolution performance of various multimetal phosphide electrode materials is evaluated by polarization curves. The current density of electrode materials with and without rare earth element doping is compared at the same potential.

[0075] In addition, commercial iridium oxide (Maclean, CAS No. 7439-88-5) was drop-coated onto a conductive nickel foam substrate (nickel foam dimensions: 1cm x 1cm, thickness: 1 mm, iridium loading mass: 5 mg / cm³). 2 Using the control sample as a reference, a test system was constructed according to the three-electrode system described in step 1 above, with the working electrode replaced by the control sample. The catalytic performance was then evaluated according to step 2. Specific test results are as follows: Figure 4 As shown in the figure, the oxygen evolution performance of the polymetallic phosphide electrode material doped with rare earth element praseodymium of the present invention is higher than that of the electrode material without rare earth element praseodymium doping and the sample without the addition of transition metal iron. This proves that the polymetallic phosphide electrode material prepared by electroplating of the present invention is beneficial to improving the catalytic performance of the anode electrode material for water electrolysis, and the electrode material prepared by the present invention has better catalytic oxygen evolution performance than commercial iridium oxide.

[0076] Application Example 2 The electrode materials obtained in Examples 4-6 were used as anode catalysts in water electrolysis systems, demonstrating the potential of electrode materials prepared from rare earth nitrates with different contents for the electrolytic oxygen application. 1. Test System Setup: The test setup was a three-electrode system. The reference electrode was Hg / HgO (1 M KOH solution), the counter electrode was a carbon rod, and the working electrodes were the electrode materials obtained in the above examples. The electrolyte was a 1 M KOH solution. A 50 mL double-layer single-cell electrolytic cell was used during the test.

[0077] 2. Catalytic performance evaluation method: The electrolytic cell temperature was maintained at room temperature, and the oxygen evolution performance of electrode materials doped with different concentrations of rare earth praseodymium was evaluated by polarization curves. Specific test results are as follows. Figure 5 As shown in the figure, the oxygen evolution performance of the polymetallic phosphide electrode material changes with the content of rare earth nitrates in the electroplating solution. Therefore, this invention can adjust the content of various elements doped in the polymetallic phosphide heterojunction electrode material by adjusting the content of rare earth nitrates in the electroplating solution, thereby preparing electrode materials with different oxygen evolution performance.

[0078] Application Example 3 The electrode materials obtained in Examples 6 and 11-13 were used as anolyte catalysts in water electrolysis systems, demonstrating the potential of multi-metal phosphide electrode materials prepared under different electroplating conditions for the application of electrolytic oxygen. 1. Test system setup: The test device is a three-electrode system. The reference electrode is Hg / HgO (1 M KOH solution), the counter electrode is a carbon rod, and the working electrodes are the electrode materials obtained in the above examples. The electrolyte is 1 M KOH solution. A 50 mL double-layer single-cell electrolytic cell is used in the test.

[0079] 2. Catalytic performance evaluation method: The electrolytic cell temperature was maintained at room temperature, and the oxygen evolution performance of the electrode materials prepared under different electroplating conditions was evaluated by polarization curves. Specific test results are as follows: Figure 6 As shown in the figure, the oxygen evolution performance of polymetallic phosphide electrode materials varies with electroplating time, current density, and temperature.

[0080] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of preparing an electrode, characterized by, The preparation method comprises the following steps: mixing a transition metal salt, a rare earth metal salt and a phosphorus source as electrolytes to obtain an electroplating solution, taking an electrically conductive substrate as a negative electrode and a metal material as a positive electrode, and depositing a multi-metal phosphide on the negative electrode substrate by an electrochemical reduction method to obtain the electrode.

2. The production method according to claim 1, characterized by, The metal elements in the transition metal salt at least include iron and molybdenum; And / or, the metal elements in the transition metal salt can also include one, two or more of manganese, cobalt, nickel, copper and zinc; And / or, the transition metal salt is a mixture of iron nitrate and its hydrate and sodium molybdate, and the molar ratio of the iron nitrate and its hydrate to the sodium molybdate is 1: (0.5-2); And / or, the transition metal salt is a mixture of iron nitrate and its hydrate, cobalt nitrate hexahydrate and sodium molybdate, and the molar ratio of the iron nitrate and its hydrate to the cobalt nitrate hexahydrate and the sodium molybdate is 1: (0.5-2): (0.5-2).

3. The production method according to claim 1 or 2, characterized by, The molar ratio of the rare earth metal salt to the transition metal salt is 1: (5-100); And / or, the molar ratio of the transition metal salt to the phosphorus source is 1: (0.5-2).

4. The production method according to any one of claims 1 to 3, characterized by, The electroplating solution further contains sodium citrate. Preferably, the molar ratio of the transition metal salt to the sodium citrate is 1: (0.05-0.2).

5. The method of any one of claims 1-4, wherein, The rare earth elements in the rare earth metal salt are at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium and gadolinium; Preferably, the phosphorus source is at least one of phosphoric acid, sodium phosphate, sodium hypophosphite monohydrate, potassium phosphate and potassium hypophosphite.

6. The method of any one of claims 1-5, wherein, The total molar concentration of metal elements in the electroplating solution is 0.01-2 mol / L -1 ; And / or, in the electroplating solution, the molar concentration of phosphorus element is 0.001-1 mol / L -1 .

7. The method of any one of claims 1-6, wherein, The electrically conductive substrate is selected from at least one of titanium felt, carbon felt, nickel mesh, foamed nickel, carbon paper and carbon cloth; And / or, the metal material is selected from at least one of manganese, iron, cobalt, nickel, copper, zinc and molybdenum; and / or the current density of the electrochemical reduction method is 0.1-1000 mA cm -2 ; the power-on time is 1-600 minutes.

8. An electrode characterized by, The electrode is obtained by the preparation method in any one of claims 1-7.

9. The electrode in claim 8 is applied in an electrocatalytic water decomposition oxygen evolution system.

10. An electrolytic system, characterized in that, It takes the electrode in claim 8 as a working electrode.

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