High-performance stainless steel-based electrolytic water dual-function electrode and application thereof

Abstract

The application discloses a high-performance stainless steel-based electrolytic water dual-function electrode and application thereof, and the electrode is prepared through the following steps: step 1, pretreating a stainless steel surface to remove impurities on the surface; step 2, placing the stainless steel obtained after the treatment in step 1 and a phosphorus source in an argon atmosphere under the condition of 350-450 DEG C, phosphorizing the stainless steel for 1-3 hours to obtain a phosphorized stainless steel electrode, wherein the linear distance between the phosphorus source and the stainless steel is kept at 5-10 cm; and step 3, placing the phosphorized stainless steel electrode obtained after the treatment in step 2 in a RuCl3 solution, and performing electrodeposition on the phosphorized stainless steel as a cathode to obtain the electrode, wherein the concentration of the RuCl3 solution is 2-8 mmol / L, the potential window during the electrodeposition is-2 V-0 V, and the electrodeposition time is 15-25 cycles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy, in particular to a high-performance stainless steel-based electrolytic water dual-function electrode and application thereof. BACKGROUND

[0002] Under the dual driving of global energy structure transformation and environmental protection, hydrogen energy is considered as the ultimate choice of future energy system due to its high energy density and other significant advantages. Large-scale application of hydrogen energy will have a significant impact on achieving fundamental green changes in energy structure. Electrolytic water hydrogen production, as an environmentally friendly and resource-rich hydrogen production method, is considered as a key way to achieve green hydrogen production. However, electrolytic water hydrogen production involves two half-reactions of hydrogen evolution and oxygen evolution, which often requires a high overpotential to drive, which not only increases the consumption of electric energy, but also limits the economy and competitiveness of electrolytic water hydrogen production technology.

[0003] Precious metal catalysts (Pt / C and RuO2) have a core position in industrial applications due to their ultra-low overpotential and excellent long-term stability. However, the scarcity and high cost of these materials make the electrolytic water hydrogen production a costly process. Although nickel-based alloy catalysts have been used in alkaline water electrolysis process, their performance still needs to be significantly improved. Therefore, the core task in the field of electrolytic water hydrogen production focuses on developing low-cost and high-efficiency catalysts, especially those based on high-abundance elements on earth. The key strategy in this direction lies in two aspects: one is to deeply tap the potential of non-precious metal materials as an effective substitute for precious metals; the other is to precisely control the amount of precious metals in transition metal matrix to construct composite catalysts, so as to achieve the optimal balance between cost and catalytic performance.

[0004] Stainless steel is cheap, abundant, and has good electrical conductivity and active elements (Fe and Ni), making it an ideal catalyst material. In addition, using stainless steel as a water electrolysis electrode not only reduces the cost of hydrogen production, but also eliminates the potential difference between the electrode and the stainless steel bipolar plate, further improving the stability and service life of the electrolytic cell. In view of this, stainless steel materials are increasingly attracting deep attention and high attention in the field of water electrolysis catalyst research. However, untreated stainless steel has poor catalytic performance and needs to be modified to meet the industrial water electrolysis demand. The modification technology of stainless steel mainly focuses on two directions: first, exposing stainless steel materials to an oxidizing environment to promote the in-situ generation of metal oxide and hydroxide layers with excellent oxygen evolution (OER) catalytic performance on the surface of stainless steel. For example, patent CN116145180A discloses a surface modification method for stainless steel, which gives the stainless steel surface good oxygen evolution catalytic activity by hydrothermal corrosion treatment and hydrothermal sulfidation treatment. However, this method still has the following problems: (1) the mixed corrosion solution composed of NaOH and NaCl and the NaS solution are easy to pollute the environment if not handled properly; (2) it is difficult to be applied to large-scale industrial production, especially when dealing with large-sized stainless steel electrodes; (3) the electrocatalytic hydrogen evolution performance is poor, so it cannot be used as a high-efficiency dual-functional catalyst. Second, other elements are introduced on the surface of stainless steel by a specific method, aiming to optimize and enhance the catalytic performance of stainless steel by means of element doping or the formation of new compounds. For example, patent CN 110093623 A discloses a preparation method of phosphatized stainless steel material, which adds stainless steel material and phosphorus source into a sealed container and heats to obtain phosphatized stainless steel material. However, this method also has limitations: (1) uneven diffusion may lead to uneven distribution of the phosphating layer on the surface of stainless steel, affecting the overall performance and appearance of the material; (2) the electrocatalytic hydrogen evolution performance of the one-step phosphating method is poor (the overpotential of the current density of 100 mA / cm 2 at 100 mA / cm

[0005] Although the existing technology improves the OER catalytic performance through surface modification methods such as oxidation and sulfidation, the hydrogen evolution overpotential of stainless steel materials is still high, which seriously restricts its wide application in the field of water electrolysis for hydrogen production. SUMMARY

[0006] In view of the above shortcomings of the prior art, the purpose of the present application is to provide a high-performance stainless steel-based water electrolysis dual-functional electrode and its application, to solve the problem that stainless steel has high overpotential when used as a catalyst for water electrolysis, can only be used as a single functional catalyst, and is difficult to meet the industrial alkaline water electrolysis demand.

[0007] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0008] A high-performance stainless steel-based electrolytic water dual-function electrode is prepared by the following steps:

[0009] Step 1: pretreating the surface of the stainless steel to remove impurities therefrom;

[0010] Step 2: placing the stainless steel obtained after Step 1 and a phosphorus source in an argon atmosphere at 350-450°C, respectively, and phosphorizing the stainless steel for 1-3 hours to obtain a phosphorized stainless steel electrode; wherein the linear distance between the phosphorus source and the stainless steel is kept at 5-10 cm; and the mass ratio of the phosphorus source to the stainless steel is 2-3;

[0011] Step 3: placing the phosphorized stainless steel electrode obtained in Step 2 in a RuCl3 solution, and performing electrodeposition with the phosphorized stainless steel as a cathode to obtain the electrode; wherein the concentration of the RuCl3 solution is 2-8 mmol / L, the potential window during electrodeposition is -2-0 V, and the electrodeposition time is 15-25 cycles.

[0012] Preferably, the content of Cr in the stainless steel is >5% and the content of Ni is >5% according to the mass percentage.

[0013] Preferably, the stainless steel contains the following components according to the mass percentage:

[0014] Cr is 16-18%, Ni is 10-14%, Si is 2-3%, Mn is 0-2%, and the balance is Fe.

[0015] Preferably, in Step 1, the stainless steel is subjected to pickling with dilute sulfuric acid; the concentration of the dilute sulfuric acid is 1-2 mol / L, and the pickling time is 10-20 minutes.

[0016] Preferably, in Step 2, the stainless steel and the phosphorus source are placed in a tube furnace, and the phosphorus source is located upstream of the stainless steel in the tube furnace, so that the substances obtained by the decomposition of the phosphorus source at high temperature can react with the stainless steel.

[0017] Preferably, in Step 2, the heating rate is 1-3°C / min.

[0018] Preferably, the phosphorus source is one or a mixture of two of NaH2PO2 and KH2PO2.

[0019] Preferably, in the electrodeposition process of Step 3, the stainless steel electrode is flipped after 10 cycles of electrodeposition, and then 10 more cycles of electrodeposition are performed.

[0020] The application also provides an application of the high-performance stainless steel-based electrolytic water dual-function electrode, and the electrode is used for electrolyzing water and simultaneously generating hydrogen and oxygen.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1、The present application generates metal phosphides (such as FeP4 and Ni2P, etc.) on the surface of stainless steel in situ through phosphating treatment. These phosphides not only improve the hydrophilicity of the surface of stainless steel, but also introduce new active sites, promoting the adsorption and dissociation of water molecules, thereby improving the efficiency of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER); at the same time, the metal phosphides form a uniform conductive layer on the surface of stainless steel, significantly improving the electrical conductivity of the electrode, which helps to increase the current density and reduce resistance loss, thereby improving the overall efficiency of water electrolysis; moreover, these phosphide layers on the surface of stainless steel are very stable, increasing the corrosion resistance and stability of the electrode, which can prolong the service life of the electrode, especially in alkaline environment, the stability of the electrode is particularly important.

[0023] 2、The present application introduces ruthenium element (Ru) to the surface of stainless steel through electrodeposition. Ruthenium is a highly efficient electrocatalyst that can significantly reduce the overpotential of HER and OER, improve the electrochemical reaction rate, and undoubtedly further enhance the catalytic activity of the electrode; in addition, the introduction of ruthenium also adjusts the electronic structure of transition metal phosphides, optimizing their catalytic performance while effectively preventing the degradation or deactivation of the electrode during long-term use, and the synergistic effect between ruthenium and phosphides further improves the durability of the electrode.

[0024] 3、The present application optimizes the preparation process. In the electrodeposition process, the stainless steel electrode is turned over after 10 circles of deposition, and then 10 circles of deposition are carried out. This operation ensures the uniform distribution of ruthenium elements on the surface of the electrode, avoids the problem of uneven local deposition, further increases the electrochemical active surface area (ECSA), and a larger ECSA means more active sites participating in the reaction, thereby improving the catalytic efficiency; at the same time, the preparation method described in the present application includes three main steps of pretreatment, phosphating treatment and electrodeposition, the whole process is relatively simple and easy to operate, compared with the traditional multi-step synthesis method, the present application reduces the complex pretreatment and post-treatment steps, and reduces the process complexity; moreover, the phosphating treatment and electrodeposition are carried out under relatively mild conditions, without the need for extreme temperature or pressure, which reduces energy consumption and equipment requirements; in particular, in the phosphating treatment, the reaction temperature is controlled between 350-450℃, which is much lower than some high-temperature synthesis methods, further saving energy; more importantly, the stainless steel substrate material used in the present application is low in price and easy to obtain, and the phosphorus source (such as NaH2PO2, KH2PO2) and ruthenium source (RuCl3) are also raw materials that are easy to obtain, combined with simple phosphating treatment and electrodeposition technology, the cost of the whole preparation process is greatly reduced, which has good industrialization prospect.

[0025] 4、The electrode described in the application is a bifunctional electrode, which has excellent HER and OER performance at the same time, and can realize efficient water electrolysis on the same electrode, which is particularly important for a full water decomposition device (i.e. an electrolytic tank for simultaneously generating hydrogen and oxygen), can simplify system design, reduce cost, and improve overall energy conversion efficiency; and since the electrode has good stability and high efficient catalytic performance, it is suitable for various water electrolysis systems, including alkaline electrolyte, neutral electrolyte and acidic electrolyte, which makes the electrode perform well in different application scenarios and has wide application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The scanning electron microscope photograph of the untreated stainless steel.

[0027] Figure 2 The scanning electron microscope photograph of the stainless steel electrode obtained in the present application Comparative Example 1.

[0028] Figure 3 The scanning electron microscope photograph of the stainless steel electrode obtained in the present application Example 1.

[0029] Figure 4 The transmission electron microscope photograph of the stainless steel electrode obtained in the present application Example 1.

[0030] Figure 5 The wetting angle of the untreated stainless steel and the stainless steel electrode obtained in the present application Comparative Example 1.

[0031] Figure 6 The wetting angle of the stainless steel electrodes obtained in the present application Example 1 and Comparative Example 2.

[0032] Figure 7 The HER performance of the untreated stainless steel, the present application Comparative Example 1, Comparative Example 2 and Comparative Example 3.

[0033] Figure 8 The OER performance of the untreated stainless steel, the present application Comparative Example 1, Comparative Example 2 and Comparative Example 3.

[0034] Figure 9 The electrochemical impedance spectrogram of the untreated stainless steel, the present application Comparative Example 1, Comparative Example 2 and Comparative Example 3.

[0035] Figure 10 The cyclic voltammetry curve of the untreated stainless steel, the present application Comparative Example 1, Comparative Example 2 and Comparative Example 3.

[0036] Figure 11 The electrochemical specific surface area spectrogram of the untreated stainless steel, the present application Comparative Example 1, Comparative Example 2 and Comparative Example 3.

[0037] In the figure, PSS is Comparative Example 1, Ru-SS is Comparative Example 2, Ru-PSS is the embodiment, and SS-Comparative is the control sample. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described clearly and completely in the present application in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the present application are within the scope of protection of the present application.

[0039] Unless otherwise specified in specific cases, the numerical ranges listed in the present application include the upper limit and the lower limit, and all integers and fractions within the range, but are not limited to the specific values listed in the defined range.

[0040] One kind of high-performance stainless steel-based electrolytic water dual-function electrode

[0041] The electrode described in the present application is prepared by the following steps:

[0042] Step 1: Pretreat the surface of the stainless steel to remove impurities on the surface thereof;

[0043] Step 2: Place the stainless steel obtained after step 1 and a phosphorus source in a 350-450℃ condition, respectively, so that the stainless steel is phosphorized for 1-3h, to obtain a phosphorized stainless steel electrode; wherein the linear distance between the phosphorus source and the stainless steel is kept at 5-10cm; the mass ratio of the phosphorus source to the stainless steel is 2-3;

[0044] Step 3: Place the phosphorized stainless steel electrode obtained in step 2 in a RuCl3 solution, and perform electrodeposition with the phosphorized stainless steel as a cathode, to obtain the electrode; wherein the concentration of the RuCl3 solution is 2-8mmol / L, the potential window during electrodeposition is -2-0V, and the electrodeposition time is 15-25 turns.

[0045] The present application is based on the problem that the overpotential of stainless steel used for catalysis of electrolysis of water is high in the prior art, and stainless steel can only be used as a single functional catalyst, which cannot meet the demand of industrial alkaline water electrolysis. The present application conceives to design the function of the stainless steel-based electrode, aiming to improve the efficiency of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of the electrode in the process of water electrolysis, and to enhance the stability and durability thereof. To this end, the present application considers phosphating the stainless steel without modification, and using the chemical reaction between the phosphorus source and the stainless steel at a specific temperature to in-situ phosphatize the iron and nickel elements on the surface of the stainless steel into FeP4 and Ni2P, which have certain OER and HER catalytic activity. This phosphating treatment not only improves the hydrophilicity of the surface of the stainless steel, which enables the bubbles generated on the surface of the stainless steel to escape in time, which is conducive to the catalytic reaction; but also forms a heterostructure of FeP4 and Ni2P, which has abundant interfaces and can provide more active sites, so that the formed phosphating layer serves as a conductive layer, improving the conductivity of the electrode; compared with the un-phosphated stainless steel, the electrode after phosphating has a significant improvement in catalytic performance and stability, especially in an alkaline environment. Secondly, the present application considers introducing ruthenium element, because the present application found in the research that introducing ruthenium (Ru) onto the surface of the phosphated stainless steel by electrodeposition can reduce the overpotential of HER and OER, thereby improving the electrochemical reaction rate; and the synergistic effect between ruthenium and phosphide can also adjust the electronic structure of the phosphide, further optimize the catalytic performance and prevent the degradation or deactivation of the electrode, which not only enhances the catalytic activity of the electrode, but also improves its durability.

[0046] In some embodiments of the present application, in step 2, the temperature of phosphating is controlled between 350-450℃. When the temperature is too high, the surface of the phosphating layer on the surface of the stainless steel is rough, forming a loose or defective film layer, which reduces its corrosion resistance and adhesion; and when the temperature is too low, the phosphorus source cannot be completely decomposed, and the metal elements on the surface of the stainless steel cannot be fully phosphated. Therefore, the phosphating temperature can be 350℃, 400℃, 450℃, etc., as well as all ranges and sub-ranges between the above-mentioned values. It should be understood that in the embodiments, any of the above-mentioned ranges can be combined with any other range in other embodiments.

[0047] In some embodiments of the present application, in step 2, the phosphating time is controlled between 1-3h. Too short time will result in too little in-situ generated metal phosphide on the surface of the stainless steel, which cannot improve the performance of the electrode; and too long time will result in accumulation of the generated metal phosphide, which is not conducive to the performance improvement of the electrode. Therefore, the phosphating time can be 1h, 1.5h, 2h, 2.5h, 3h, etc., as well as all ranges and sub-ranges between the above-mentioned values. It should be understood that in the embodiments, any of the above-mentioned ranges can be combined with any other range in other embodiments.

[0048] In some embodiments of the present application, in step 2, the linear distance between the phosphorus source and the stainless steel is kept at 5-10 cm, too close to each other will cause the in-situ grown metal phosphide on the surface of the stainless steel to be uneven; while too far apart is not conducive to the growth of the phosphide. Therefore, the linear distance between the phosphorus source and the stainless steel can be 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, etc., as well as all ranges and sub-ranges between the above-mentioned values. It should be understood that in the embodiments, any of the above-mentioned ranges can be combined with any other range in other embodiments.

[0049] In some embodiments of the present application, in step 2, the mass ratio of the phosphorus source to the stainless steel is 2-3. Too little amount of phosphorus source will cause the metal elements on the surface of the stainless steel to be insufficiently phosphatized; while too much amount of phosphorus source will cause the excess phosphorus source to be blown to the surface of the stainless steel by argon, thereby contaminating the sample. Therefore, the mass ratio of the phosphorus source to the stainless steel can be 2:1, 2.5:1, 3:1, etc., as well as all ranges and sub-ranges between the above-mentioned values. It should be understood that in the embodiments, any of the above-mentioned ranges can be combined with any other range in other embodiments.

[0050] In some embodiments of the present application, the concentration of the RuCl3 solution is between 2-8 mmol / L, too low concentration of Ru elements is difficult to deposit on the stainless steel electrode, and too high concentration will cause the Ru elements to accumulate.

[0051] In some embodiments of the present application, according to the mass percentage, the content of Cr in the stainless steel is >5%, and the content of Ni is >5%. The present application is applicable to almost all stainless steels with a mass fraction of Ni greater than 5%. When the content of Ni in the stainless steel is low, Ni2P cannot be formed on the surface of the electrode. It is further preferred that the stainless steel contains the following components according to the mass percentage: Cr is 16-18%, Ni is 10-14%, Si is 2-3%, Mn is 0-2%, and the balance is Fe.

[0052] In some embodiments of the present application, in step 1, the stainless steel is pickled with dilute sulfuric acid; the concentration of the dilute sulfuric acid is 1-2 mol / L, and the pickling time is 10-20 min. The function of the dilute sulfuric acid is to remove the rust and impurities on the surface of the stainless steel, so as to avoid affecting the effect of the subsequent annealing treatment. Therefore, the concentration of the dilute sulfuric acid should not be too high, otherwise the stainless steel will be corroded too much, and the subsequent annealing treatment will have adverse effects. On the other hand, the concentration of the dilute sulfuric acid should not be too low, otherwise it will not have the cleaning effect. The concentration of the dilute sulfuric acid can be 1 mol / L, 1.5 mol / L, 2 mol / L, etc., as well as all ranges and sub-ranges between the above-mentioned values. The pickling time can be controlled at 10 min, 15 min, 20 min, etc., as well as all ranges and sub-ranges between the above-mentioned values. It should be understood that in the embodiments, any of the above-mentioned ranges can be combined with any other range in other embodiments.

[0053] In some embodiments of the present application, in step 2, the stainless steel and the phosphorus source are placed in a tube furnace respectively, and the phosphorus source is located upstream of the stainless steel in the tube furnace. In this way, when the phosphorus source upstream is decomposed at high temperature, the substances generated can flow along the direction of the gas flow in the furnace, so that the substances obtained by the decomposition of the phosphorus source at high temperature can react with the stainless steel.

[0054] In some embodiments of the present application, in step 2, the heating rate is 1-3 ℃ / min. Controlling the heating rate can ensure the stable and continuous decomposition of the phosphorus source. If the heating rate is too slow, the reaction efficiency will be reduced and the energy consumption will be increased. On the other hand, if the heating rate is too fast, the decomposition rate of the phosphorus source will be too fast, which will prevent it from fully phosphating with the metal elements on the surface of the stainless steel, and thus not enough metal phosphides can be generated. Therefore, the heating rate can be 1 ℃ / min, 2 ℃ / min, 3 ℃ / min, etc., as well as all ranges and sub-ranges between the above-mentioned values. It should be understood that in the embodiments, any of the above-mentioned ranges can be combined with any other range in other embodiments.

[0055] In some embodiments of the present application, the phosphorus source is one or a mixture of NaH2PO2 and KH2PO2. In the present application, one or a mixture of NaH2PO2 and KH2PO2 is preferred. If other phosphorus sources are used, unnecessary side reactions will easily occur, which will contaminate the surface of the stainless steel with by-products and adversely affect the performance of the stainless steel electrode.

[0056] In some embodiments of the present application, in the electrodeposition process of step 3, the stainless steel electrode is first deposited for 10 turns, then turned over, and then electrodeposited for another 10 turns, so as to ensure the uniform distribution of ruthenium elements on the surface of the electrode, increase the electrochemical active surface area (ECSA), and thus improve the catalytic efficiency.

[0057] In some embodiments of the present application, in step 3, the potential window during electrodeposition is -1.5V-0.5V. If the potential window is too small, the formation potential range of the target deposit may not be covered, resulting in a reduced deposition rate, slow growth of the deposition layer, and thus reduced overall deposition efficiency. If the potential window is too large, not only will the energy consumption increase, but the stability of the deposition process will also be affected. Therefore, the potential window during electrodeposition can be -1.5V-0.5V, -2.0V-1V, -1V-0V, etc., as well as all ranges and sub-ranges between the above-mentioned values. During the electrodeposition process, the deposition time is controlled to be 15-25 cycles. If the deposition time is too short, the amount of deposit on the stainless steel electrode material will be insufficient, and a short deposition time may not be able to form a complete and dense deposit structure. If the deposition time is too long, not only will the energy consumption increase, but more side reactions may also occur, affecting the catalytic performance of the stainless steel electrode. Therefore, the deposition time is preferably 20 cycles, and can be 15 cycles, 20 cycles, 25 cycles, etc., as well as all ranges and sub-ranges between the above-mentioned values. It should be understood that in the embodiments, any of the above-mentioned ranges can be combined with any other range in other embodiments.

[0058] II. Use of a high-performance stainless steel-based electrolytic water dual-function electrode

[0059] The above electrode is used for alkaline electrolytic water and simultaneously evolves hydrogen and oxygen. In the process of electrolytic water, it can not only act as an anode to evolve oxygen, but also as a cathode to evolve hydrogen.

[0060] III. Examples and comparative examples

[0061] Example 1

[0062] Step 1: Pretreatment of stainless steel material

[0063] Take 316L foam stainless steel, cut the 316L foam stainless steel into a rectangular shape, polish the surface of the stainless steel with 500-mesh sandpaper for 5 minutes, then immerse it in a 1 mol / L dilute sulfuric acid solution for 20 minutes, then slowly rinse it with deionized water for 3 minutes, and dry it for 6 hours to obtain a rectangular stainless steel sheet.

[0064] Step 2: Preparation of phosphated stainless steel electrode

[0065] Place the stainless steel treated in step 1 in a tube furnace, place 2g of NaH2PO2 as a phosphorus source upstream of the tube furnace under an argon atmosphere, and place the stainless steel downstream of the tube furnace for annealing for 2h to obtain an annealed stainless steel electrode; wherein the phosphating temperature is 400°C, and the heating rate is 5°C / min; the distance between the phosphorus source and the stainless steel two crucibles is kept at 5-10 cm.

[0066] Step 3: Preparation of dual-function stainless steel electrode

[0067] The stainless steel electrode treated in step 2 is placed in a RuCl3 electrolyte, and the stainless steel is used as a cathode to perform electrodeposition to obtain the stainless steel bifunctional electrode; wherein the concentration of RuCl3 in the electrolyte is 5 mmol / L, the potential window during electrodeposition is-1.5-0.5 V, and the electrodeposition time is 20 cycles.

[0068] Example 2

[0069] On the basis of example 1, the improvement lies in that in step 2, the mass of NaH2PO2 is 1.5 g.

[0070] Example 3

[0071] On the basis of example 1, the improvement lies in that in step 2, the mass of NaH2PO2 is 2.5 g.

[0072] Example 4

[0073] On the basis of example 1, the improvement lies in that in step 2, the phosphating temperature is 350℃.

[0074] Example 5

[0075] On the basis of example 1, the improvement lies in that in step 2, the phosphating temperature is 450℃.

[0076] Example 6

[0077] On the basis of example 1, the improvement lies in that in step 3, the potential window is-2.0--1.0 V.

[0078] Example 7

[0079] On the basis of example 1, the improvement lies in that in step 3, the potential window is-1.0-1.0 V.

[0080] Example 8

[0081] On the basis of example 1, the improvement lies in that in step 3, the deposition time is 15 cycles.

[0082] Example 9

[0083] On the basis of example 1, the improvement lies in that in step 3, the deposition time is 25 cycles.

[0084] Comparative Example 1

[0085] On the basis of example 1, the improvement lies in that step 3 is not performed.

[0086] Comparative Example 2

[0087] An improvement is made based on Example 1, the difference being that step 2 is omitted, and the stainless steel obtained from step 1 is directly processed in step 3.

[0088] Comparative Example 3

[0089] An improvement on Example 1, the difference being that in step 2, the phosphating temperature is 300°C.

[0090] Comparative Example 4

[0091] An improvement on Example 1, the difference being that in step 2, the phosphating temperature is 500°C.

[0092] Comparative Example 5

[0093] An improvement on Example 1 is made, the difference being that in step 3, the electrodeposition time is 10 cycles.

[0094] Comparative Example 6

[0095] An improvement on Example 1 is made, the difference being that in step 3, the electrodeposition time is 30 cycles.

[0096] III. Performance Analysis

[0097] 1. Catalyst microstructure

[0098] Both the examples and untreated stainless steel (control sample) were examined for their microstructure using a JEOL JSM-7800F scanning electron microscope and a Talos F200S transmission electron microscope. Figure 1 and Figure 2 As can be seen, the untreated stainless steel surface is relatively smooth, with some irregular textures, small pores, and particles; the stainless steel electrode surface of Comparative Example 1, after annealing, shows a lamellar structure of phosphide. These structures intertwine to form a complex three-dimensional network structure, indicating that the phosphide film has good adhesion and coverage. At the same time, the bonding force between the phosphide film and the substrate is very strong, making it difficult to detach or peel off, which provides an ideal underlying structure for subsequent electrodeposition.

[0099] Depend on Figure 3 As can be seen, after electrodeposition treatment of the phosphated stainless steel, the surface of the stainless steel in Example 1 still exhibits an interwoven lamellar structure. Furthermore, from Figure 4The transmission electron micrograph of the surface of the stainless steel electrode of Example 1 also shows that the active substance on the surface of the stainless steel electrode of Example 1 presents a stacked sheet structure, which indicates that the structure of the phosphating film is not destroyed by the electrodeposition process, but continues to maintain its integrity, which shows that the structure of the surface of the stainless steel electrode of Example 1 has good thermal stability and chemical stability.

[0100] 2. Measurement of overpotential

[0101] The examples and comparative examples, as well as the stainless steel without any treatment (control sample), were placed on a CHI 1140C electrochemical workstation produced by Shanghai Chenhua Instrument Co., Ltd. to measure the LSV curve. A three-electrode system was used for hydrogen evolution and oxygen evolution performance testing, with the stainless steel electrode as the anode, a graphite rod as the cathode, Hg / HgO as the reference electrode, and 1 mol / L KOH solution as the electrolyte. This method is different from the third step of electrodeposition.

[0102] Table 1: Overpotential measurement results (HER) of different stainless steel base electrodes

[0103]

[0104] Table 2: Overpotential measurement results (OER) of different stainless steel base electrodes

[0105]

[0106]

[0107] From Figures 7-8 and Tables 1-2, it can be seen that:

[0108] (1) In terms of hydrogen reaction (HER) performance:

[0109] At a current density of 10 mA / cm 2 , the overpotential of the examples is significantly lower than that of all the comparative examples and the control sample, which indicates that the examples have a lower starting potential, meaning that the examples can start the effective hydrogen evolution reaction at a lower voltage.

[0110] At current densities of 500 mA / cm 2 and 1000 mA / cm 2 , the overpotential of the examples is also significantly lower than that of the comparative examples and the control sample, which shows that the examples still maintain high catalytic efficiency at high current density, effectively reducing energy consumption.

[0111] (2) In terms of oxygen evolution reaction (OER) performance:

[0112] For 10 mA / cm 2The overpotential of the examples ranged from 266 to 279 mV, while the overpotential of the comparative examples 1-6 ranged from 275 to 310 mV, and the overpotential of the control sample was 308 mV. The overpotential of the examples was slightly higher than that of some of the comparative examples, but was still relatively low overall. Although the difference was not large, the relatively low overpotential of the examples still helped to improve the reaction efficiency in this case.

[0113] At a current density of 500 mA / cm 2 and 1000 mA / cm 2 , the overpotential of the examples was significantly lower than that of the comparative examples and the control sample, indicating that the examples exhibited more excellent OER performance at high current density, effectively reducing energy consumption and increasing reaction rate.

[0114] (3) Comprehensive advantages:

[0115] Whether it was HER or OER, the overpotential of the examples at different current densities was significantly lower than that of the comparative examples and the control sample, showing higher catalytic activity, which indicated that the examples could achieve efficient water electrolysis at lower voltage, thereby improving energy conversion efficiency. Due to the phosphating treatment and the introduction of ruthenium elements in the examples, these improvements not only improved the catalytic performance of the electrode, but also enhanced its stability and durability; especially for long-term running electrolyzers, stable electrode performance is crucial. From low to high current density, the examples showed good performance, which means it is suitable for a wider range of applications, including but not limited to small laboratory equipment, industrial-scale water electrolysis devices, etc.

[0116] 3. Electrochemical impedance measurement

[0117] The examples and comparative examples, as well as stainless steel without any treatment (control sample), were placed on a CHI1140C electrochemical workstation produced by Shanghai Chenhua Instrument Co., Ltd. to measure the electrochemical impedance (EIS).

[0118] Table 3 Electrochemical impedance measurement results of different stainless steel-based electrodes

[0119] Sample name Electrochemical impedance (Ω) Comparative Example 1 0.38 Comparative Example 2 0.41 Comparative Example 3 0.66 Comparative Example 4 0.42 Comparative Example 5 0.54 Comparative Example 6 0.39 Example 1 0.28 Example 2 0.26 Example 3 0.32 Example 4 0.33 Example 5 0.27 Example 6 0.28 Example 7 0.32 Example 8 0.30 Example 9 0.35 Control sample 0.44

[0120] From Figure 9 and Table 3, we can see that:

[0121] (1) As can be seen from Table 2, the electrochemical impedance of Examples 1-9 ranges from 0.26 to 0.35 Ω, the electrochemical impedance of Comparative Examples 1-6 ranges from 0.38 to 0.66 Ω, and the electrochemical impedance of the untreated stainless steel (control sample) is 0.44 Ω; this indicates that after phosphating treatment and the introduction of ruthenium element, the electrical conductivity of the stainless steel-based electrode is significantly improved, and the resistance loss is small; compared with the examples, the electrochemical impedance of the comparative examples is generally higher, which indicates that the comparative examples may encounter greater resistance loss during electrolysis, resulting in a decrease in energy conversion efficiency; and the control example further confirms the deficiencies of untreated stainless steel in terms of electrical conductivity and catalytic activity.

[0122] (2) As can be seen from Figure 9 , the Nyquist plots obtained by electrochemical impedance spectroscopy testing of the stainless steel-based bifunctional water electrolysis electrodes prepared in Examples and Comparative Examples and the untreated stainless steel all exhibit a semi-circular shape. Since the smaller the radius of the Nyquist plot (i.e., the impedance plot) semicircle, the lower the impedance of the material.

[0123] (3) The electrochemical impedance of the examples is significantly lower than that of the comparative examples and the control sample, which indicates that the examples can more effectively conduct current during water electrolysis, reducing resistance loss; lower resistance loss helps to improve electrolysis efficiency, reduce energy consumption, and improve the overall performance of the system. At the same time, phosphating treatment forms a uniform conductive layer on the surface of the stainless steel, significantly improving the electrical conductivity of the electrode; moreover, the introduction of ruthenium element not only enhances the catalytic activity but also adjusts the electronic structure of the transition metal phosphide, further optimizing the electrical conductivity of the electrode; ultimately, due to the lower electrochemical impedance, the examples can achieve a higher current density under the same working conditions, thereby improving the efficiency of water electrolysis; lower resistance loss also means less heat generation, which helps to maintain the stable operation of the system and prolong the service life of the electrode.

[0124] 4. Measurement of electrochemical specific surface area

[0125] Examples and Comparative Examples, as well as untreated stainless steel (control sample), were placed on a CHI1140C electrochemical workstation produced by Shanghai Chenhua Instrument Co., Ltd. to measure the cyclic voltammetry curve (CV curve), and the electrochemical specific surface area (C dl ) of each sample was obtained by fitting the cyclic voltammetry curve.

[0126] Table 4 Measurement results of electrochemical specific surface area of different stainless steel-based electrodes

[0127] Sample name Electrochemical specific surface area (mF cm -2 ) Comparative Example 1 22.5 Comparative Example 2 9.4 Comparative Example 3 12.2 Comparative Example 4 25.2 Comparative Example 5 25.5 Comparative Example 6 29.6 Example 1 44.8 Example 2 36.8 Example 3 38.3 Example 4 42.5 Example 5 44.3 Example 6 43.6 Example 7 40.2 Example 8 43.7 Example 9 42.2 Control sample 4.7

[0128] As can be seen from Table 4 and Figures 10-11 , it can be seen that:

[0129] (1) As can be seen from Table 4, the ECSA of Examples 1-9 ranges from 36.8-44.8 mF·cm-2, which indicates that after phosphating treatment and introduction of ruthenium element, the surface activity of the stainless steel-based electrode is significantly increased, providing more active sites; the ECSA of Comparative Examples 1-6 ranges from 9.4-29.6 mF·cm-2, which is generally lower than that of the examples, meaning that they have fewer active sites to participate in the reaction under the same conditions, and the catalytic efficiency is relatively low; moreover, Comparative Example 1 and Comparative Example 2 only perform one step of the method described in the present application, so it can be seen that such treatment is quite limited in improving the electrochemical specific surface area; and the ECSA of the stainless steel without any treatment (control sample) is only 4.7 mF·cm-2, which is much lower than all examples and most of the comparative examples, further confirming that the untreated stainless steel has very limited ability to provide active sites.

[0130] (2) The ECSA of the examples is significantly higher than that of the comparative examples and the control sample, which indicates that the examples have more surface active sites, which can more effectively adsorb and dissociate water molecules, thereby improving the catalytic efficiency of the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER); more active sites also mean a larger reaction interface, which helps to increase the current density and reaction rate. This further proves that the phosphating treatment generates metal phosphides (such as FeP4, Ni2P, etc.) on the surface of the stainless steel, which not only improves the surface hydrophilicity but also introduces new active sites; the introduction of ruthenium element also enhances the catalytic activity of the electrode and optimizes the catalytic performance; this combination makes the examples exhibit higher catalytic efficiency in the HER and OER processes; ultimately, due to the higher ECSA of the examples, they can achieve higher current density under the same voltage, thereby improving the overall efficiency of water electrolysis, and more active sites also help to reduce the overpotential, reduce energy consumption, and improve the energy conversion efficiency of the system; at the same time, through phosphating treatment and the introduction of ruthenium element, the examples not only improve the catalytic activity but also enhance the stability and durability of the electrode, especially during long-term operation, more active sites can effectively prevent electrode degradation or deactivation, prolonging the service life of the electrode; high ECSA makes the examples suitable for various water electrolysis systems, including alkaline, neutral and acidic electrolytes, and this wide applicability makes the examples perform well in different application scenarios, having broad application prospects.

[0131] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the technical solutions. Those of ordinary skill in the art should understand that modifications or equivalent replacements to the technical solutions of the present application without departing from the spirit and scope of the technical solutions should be covered within the scope of the claims of the present application.

Claims

1. A high-performance stainless steel-based electrolytic water dual functional electrode, characterized by, The electrode is prepared by the following steps: Step 1: pretreating the surface of the stainless steel to remove impurities therefrom; Step 2: placing the stainless steel obtained after Step 1 and a phosphorus source in an argon atmosphere at 350-450 DEG C, respectively, and phosphorizing the stainless steel for 1-3 hours to obtain a phosphorized stainless steel electrode; wherein the linear distance between the phosphorus source and the stainless steel is kept at 5-10 cm; and the mass ratio of the phosphorus source to the stainless steel is 2-3; Step 3: placing the phosphorized stainless steel electrode obtained after Step 2 in a RuCl3 solution, and performing electrodeposition with the phosphorized stainless steel as a cathode to obtain the electrode; wherein the concentration of the RuCl3 solution is 2-8 mmol / L, the potential window during electrodeposition is -2 V-0 V, and the electrodeposition time is 15-25 cycles; According to the mass percentage, the content of Cr in the stainless steel is >5%, and the content of Ni is >5%.

2. The electrode of claim 1, wherein According to the mass percentage, the stainless steel comprises the following components: Cr is 16-18%, Ni is 10-14%, Si is 2-3%, Mn is 0-2%, and the balance is Fe.

3. The electrode of claim 1, wherein In Step 1, the stainless steel is pickled with dilute sulfuric acid; the concentration of the dilute sulfuric acid is 1-2 mol / L, and the pickling time is 10-20 minutes.

4. The electrode of claim 1, wherein In Step 2, the stainless steel and the phosphorus source are placed in a tube furnace, and the phosphorus source is located upstream of the stainless steel in the tube furnace, so that the substances obtained by decomposing the phosphorus source at high temperature can react with the stainless steel.

5. The electrode of claim 1, wherein In Step 2, the heating rate is 1-3 DEG C / min.

6. The electrode of claim 1, wherein The phosphorus source is one of NaH2PO2 and KH2PO2 or a mixture of the two.

7. The electrode of claim 1, wherein In the electrodeposition process of Step 3, the stainless steel electrode is turned over after 10 cycles of electrodeposition, and then 10 cycles of electrodeposition are performed.

8. The use of high-performance stainless steel-based electrolytic water dual-function electrode, characterized in that, The electrode of any of claims 1-7 is used for electrolysis of water while simultaneously generating hydrogen and oxygen.

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