Preparation method and application of industrial-grade alkaline water electrolytic bath cathode catalyst adapting to fluctuating renewable energy sources
By preparing WMo-CoP@NM catalysts on nickel, the problem of catalyst instability in AWE technology is solved, and high stability and anti-inverse current performance under volatile renewable energy is achieved. It is suitable for industrial-grade alkaline water electrolytic cells.
Patent Information
- Application Number
- CN202510369112.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-07-18
AI Technical Summary
Existing AWE technologies are difficult to adapt to the volatility of renewable energy, resulting in unstability, aggregation and dissolution of catalysts, affecting electrode life, and lack considerations for start-up, high power fluctuations or stop operations.
A WMo-CoP@NM catalyst was prepared on nickel network by one-step electrodeposition method. Doping CoP by W/Mo bimetallic element to form a super hydrophilic amorphous structure, improving the stability and anti-reverse current performance of the catalyst.
Under volatile renewable energy conditions, the catalyst exhibits ultra-high stability and durability, and can operate stably at ampere-level current density and fluctuating current density, extending the electrode life and meeting the requirements of AWE devices.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electrolyzed water, and particularly to a preparation method and application of a cathode catalyst for an industrial alkaline water electrolyzer adapted to fluctuating renewable energy. Background Art
[0002] Producing hydrogen using renewable energy has been recognized as a viable solution to the energy crisis. Unfortunately, although the AWE technology is currently the most mature technology, it still has difficulty adapting to the unstable energy input / output problems associated with renewable energy. Because the fluctuation of the current will cause the fluctuation of bubble generation during the HER process, which will lead to catalyst instability, aggregation and dissolution. In fact, the fluctuating conditions pose a major obstacle to the electrode stability in the electrolyzer. In addition, after the current of the AWE electrolyzer is turned off, the electrolyzer returns to the equilibrium state, forming a reverse current, which oxidizes the cathode catalyst, thus shortening the life of the electrolyzer. However, most of the current studies on the electrode catalysts of the AWE system lack the consideration of start-up, high-power fluctuations or stop operations, and the catalyst performance is usually mainly tested at a constant power. Therefore, it is crucial to create a robust electrode that has excellent countercurrent resistance without additional protective current.
[0003] Among non-noble metal electrocatalysts, CoP stands out among the candidate materials due to its excellent HER performance and has been widely studied as a HER catalyst. However, both the charge transfer and the intrinsic catalytic activity of single CoP have certain limitations, which hinder the continuation of the reaction. Therefore, here we propose a new method for preparing WMo-CoP@NM electrocatalytic water decomposition catalyst on a nickel mesh with excellent mechanical strength by doping CoP with W / Mo bimetallic elements. This strategy makes up for the intrinsic deficiency of the nickel mesh with a flat surface while ensuring the stability of the catalyst, making the catalyst have a super-hydrophilic surface and greatly reducing the charge transfer resistance. At the same time, surprisingly, the catalyst exhibits ultra-high stability, durability and excellent countercurrent resistance performance, basically meeting the requirements of AWE for intermittent and unpredictable renewable energy. Summary of the Invention
[0004] The purpose of the present invention is to provide a method and application of a cathode catalyst for an industrial alkaline water electrolyzer adapted to fluctuating renewable energy. The preparation method is one-step electrodeposition and has excellent hydrogen evolution performance. More importantly, compared with other CoP-based catalysts widely studied at present, this study can operate stably under ampere-level current density conditions and fluctuating current density conditions, which has guiding significance for the research of hydrogen evolution catalysts under industrial conditions.
[0005] In order to achieve the above-mentioned invention purpose, the technical solutions adopted by the present invention are as follows:
[0006] In a first aspect, a method for preparing a cathode catalyst for an industrial alkaline water electrolyzer adapted to volatile renewable energy is provided, including the following steps:
[0007] Mix a tungsten source, a cobalt source, a molybdenum source, a phosphorus source, an ammonium salt, and a citrate into a solution. Subsequently, place a nickel mesh (NM) into the solution and perform electrodeposition at room temperature. After the reaction ends, wash it several times with deionized water and ethanol, and dry it in an oven for standby.
[0008] In the step, the cobalt source, that is, the source of cobalt, can be any one or more of various cobalt salts such as cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt carbonate, and cobalt fluoride;
[0009] In the step, the tungsten source, that is, the source of tungsten, can be any one or more of various tungsten salts and tungstates such as tungsten chloride, sodium tungstate, calcium tungstate, and ammonium tungstate;
[0010] In the step, the molybdenum source, that is, the source of molybdenum, can be any one or more of various molybdates such as sodium molybdate, ammonium molybdate, calcium molybdate, zinc molybdate, molybdenum oxide, and molybdenum disulfide;
[0011] In the step, the phosphorus source, that is, the source of phosphorus, can be any one or more of various hypophosphites, hypophosphates, and phosphates;
[0012] In the step, the ammonium salt, that is, the source of the ammonium salt, can be any one or more of various ammonium salts such as ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate, and ammonium phosphate;
[0013] In the step, the citrate, that is, the source of the citrate, can be any one or more of various citrates such as sodium citrate, potassium citrate, and calcium citrate.
[0014] Preferably, in the preparation step, CoCl2, WCl6, Na2MoO4, C6H5Na3O7, NH4Cl, and NaH2PO2 are dissolved in deionized water. For every 0.5 - 6 mmol of CoCl2, it corresponds to 50 ml of deionized water, 0.2 - 4 mmol of WCl6, 0.2 - 5 mmol of Na2MoO4, 0.5 - 5 mmol of C6H5Na3O7, 4 - 50 mmol of NH4Cl, and 2 - 40 mmol of NaH2PO2. After mixing evenly, place the treated NM for electrodeposition; NM serves as the cathode, and under the condition of 5 - 200 mA cm -2 (preferably 25 - 100 mA cm -2 ), perform electrodeposition for 10 - 250 min, and dry to obtain WMo - CoP@NM, that is, the target cathode catalyst.
[0015] In a second aspect, it further includes a highly efficient electrocatalyst prepared by the above preparation method. Preferably, the highly efficient electrocatalyst is applied to water electrolysis under alkaline aqueous solution conditions and alkaline seawater conditions.
[0016] In an AWE electrolyzer with WMo-CoP@NM as the cathode, commercial nickel mesh as the anode, and PPS as the diaphragm, the stable current density during the operation of the electrolyzer is 0.2 - 3.0 A cm -2 .
[0017] When using the WMo-CoP@NM of the present invention as the cathode, commercial nickel mesh as the anode, and PPS as the diaphragm in an AWE electrolyzer, it exhibits performance far superior to that of commercial electrolyzers, and at a current density of 1.0 A cm -2 , the electrolyzer can maintain stable operation for more than 1500 hours.
[0018] It has excellent reverse current resistance performance and can be not affected by the oxidation effect of the forward current during the start-up and shutdown processes of the electrolyzer.
[0019] When using WMo-CoP@NM as the cathode, commercial nickel mesh as the anode, and PPS as the diaphragm in an AWE electrolyzer, at low current density (0.4 A cm -2 A cm -2 ) and high current density (1.5 A cm -2 ), it maintains good stability and even more excellent performance during fifty alternating cycle tests of different current densities.
[0020] When using WMo-CoP@NM as the cathode, commercial nickel mesh as the anode, and PPS as the diaphragm in an AWE electrolyzer, at low current density (0.4 A cm -2 ), high current density (1.5 A cm -2 ), and power outage (0 A cm -2 ), it maintains good stability during fifty alternating cycle tests, verifying its application in the field of electrolyzing water with fluctuating power supplies.
[0021] The preparation method of WMo-CoP@NM is simple and low-cost, and large-scale preparation can be achieved (the area of WMo-CoP@NM can reach at least 225 cm 2 ), and it still maintains excellent performance, verifying the possibility of its commercial application.
[0022] The beneficial effects of the present invention are as follows:
[0023] The present invention adopts the method of electro-depositing tungsten(VI) chloride, cobalt chloride, sodium molybdate, sodium hypophosphite, ammonium chloride and sodium citrate solutions at room temperature to grow phosphides of tungsten, molybdenum and cobalt on a nickel mesh, and finally form a super-hydrophilic amorphous structure on the smooth surface of the nickel mesh. This super-hydrophilicity improves mass transfer by accelerating the acceptance of the electrolyte, forces the release of hydrogen bubbles, and prolongs the electrode life by reducing the adhesion of bubbles during the electrolysis of water. At the same time, the cathode catalyst studied in the present invention exhibits ultra-high stability and durability, basically meeting the requirements of AWE for intermittent and unpredictable renewable energy. This work opens a new door for the preparation of catalysts with high performance, high stability and adaptability to fluctuating renewable energy, which are loaded on a commercial nickel mesh substrate for HER and OER. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. Figure 1 is the synthesis flow chart of Example 1;
[0025] FIG. Figure 2 is the scanning electron microscope (SEM) images of Example 1 and Comparative Example 1;
[0026] FIG. Figure 3 is the SEM and elemental mapping images of Example 1;
[0027] FIG. Figure 4 is the X-ray photoelectron spectroscopy (XPS) images of Example 1 and Comparative Examples 1-4;
[0028] FIG. Figure 5 is the hydrogen evolution performance comparison diagram of Examples 1-4 in 1M KOH solution after 90% iR correction;
[0029] FIG. Figure 6 is the hydrogen evolution performance comparison diagram of Example 1 and Comparative Examples 1-4 in 1M KOH solution after 90% iR correction;
[0030] FIG. Figure 7 is the hydrogen evolution performance stability diagram of Example 1 in 1M KOH solution;
[0031] FIG. Figure 8 is the XPS of Example 1 before and after stable operation in 1M KOH solution;
[0032] FIG. Figure 9 is the hydrogen evolution performance diagram of Example 1 in simulated seawater alkaline solution and real seawater alkaline solution with different concentrations;
[0033] FIG. Figure 10 is the hydrogen evolution performance stability diagram of Example 1 in real seawater alkaline solution;
[0034] FIG. Figure 11 is the alkaline water electrolysis for hydrogen production (AWE) performance stability diagram of Example 1;
[0035] Attached Figure 12 is the countercurrent resistance performance of Example 1 (without IR compensation);
[0036] Attached Figure 13 is the accelerated degradation test of the AWE system of Example 1 under variable current load (30 wt% KOH, 65 °C);
[0037] Attached Figure 14 is the physical picture of the catalyst material prepared by the scale-up experiment of Example 1;
[0038] Attached Figure 15 is the overpotential distribution diagram of each part after cutting the catalyst material prepared by the scale-up experiment of Example 1 into nine parts (5×5 cm 2 ) at 0.5 A cm -2 . Detailed implementation method
[0039] The present invention provides a preparation method of an industrial-grade alkaline water electrolyzer cathode catalyst WMo-CoP@NM adapted to fluctuating renewable energy.
[0040] In the present invention, unless otherwise specified, the required preparation raw materials are all commercially available products well-known to those skilled in the art.
[0041] The present invention provides the application of the industrial-grade alkaline water electrolyzer cathode catalyst WMo-CoP@NM adapted to fluctuating renewable energy described in the above technical solution in water electrolysis. The present invention has no special limitation on the method of the application, and it can be applied according to the methods well-known in the art.
[0042] The following further illustrates the present invention with specific examples. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0043] Example 1:
[0044] 2.5 mmol CoCl2, 1 mmol WCl6, 1 mmol Na2MoO4, 12.5 mmol NaH2PO2, 25 mmol NH4Cl, 2.5 mmol C6H5Na3O7 are dissolved in 50 ml of deionized water. After mixing evenly, the treated NM is added. Using NM as the cathode, the reaction is carried out for 2 h at a current density of 50 mA cm -2 , and then dried in vacuum at 40 °C to obtain WMo-CoP@NM.
[0045] Example 2:
[0046] Except that the current density is changed to 25 mA cm -2 , other implementation manners are the same as those in Example 1, but what is obtained is WMo-CoP@NM-25.
[0047] Example 3:
[0048] Except that the current density is changed to 75 mA cm -2 , other implementation manners are the same as those in Example 1, but what is obtained is WMo-CoP@NM-75.
[0049] Example 4:
[0050] Except that the current density is changed to 100 mA cm -2 , other implementation manners are the same as those in Example 1, but what is obtained is WMo-CoP@NM-100.
[0051] Comparative Example 1:
[0052] CoP@NM is obtained by the same method as in Example 1, but the introduction of tungsten source and molybdenum source is no longer carried out.
[0053] Comparative Example 2:
[0054] W-CoP@NM is obtained by the same method as in Example 1, but the introduction of molybdenum source is no longer carried out.
[0055] Comparative Example 3:
[0056] Mo-CoP@NM is obtained by the same method as in Example 1, but the introduction of tungsten source is no longer carried out.
[0057] Comparative Example 4:
[0058] WMo-Co@NM is obtained by the same method as in Example 1, but the phosphating treatment is no longer carried out.
[0059] The above are only the preferred implementation manners of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.
[0060] Material Characterization and Testing
[0061] Figure 1 It is the preparation process of the WMo-CoP@NM catalyst;
[0062] Figure 2 It shows that the successful preparation of Example 1 and Comparative Example 1 and the morphology of the catalyst layer coated with nickel mesh. Compared with Comparative Example 1, the loading in Example 1 is more uniform;
[0063] Figure 3It is demonstrated that the successful preparation of Example 1 is achieved, and it can be seen that each element is evenly distributed;
[0064] Figure 4 It is demonstrated that during the successful construction of the WMo-CoP@NM catalyst in Example 1, both W and Mo have significant effects on the electronic structure of CoP, and there is a strong electronic coupling effect between them. Moreover, the significant adjustment of the electronic structure also improves the catalytic performance and stability of the catalyst to a certain extent;
[0065] Figure 5 It is demonstrated that among the WMo-CoP@NM catalysts with different catalyst layer thicknesses prepared using different current densities (Example 1, Example 2, Example 3, Example 4), the appropriate catalyst layer thickness, i.e., Example 1, exhibits the best hydrogen evolution catalytic performance; (The measured potential is converted using the formula with the reversible hydrogen electrode (RHE): E RHE = E Hg / HgO + 0.098 + 0.059×pH. Using 1M KOH solution as the electrolyte, linear sweep voltammetry (LSV) is recorded at a scan rate of 5 mV s -1 , and by default, all LSV curves are corrected for 90% iR)
[0066] Figure 6 It is demonstrated that the synergistic effect of jointly regulating CoP by W and Mo can effectively improve the hydrogen evolution catalytic performance relative to CoP (Example 1, Comparative Example 1), and it exhibits more excellent catalytic performance than the HER reference catalyst Pt / C and commercial Raney Ni; (The linear sweep conditions are Figure 5 the same).
[0067] Figure 7 It is demonstrated that for the self-supported catalyst of Example 1 in an alkaline solution, when the current density is 500 mA cm -2 , the electrolysis water reaction lasts for up to 100 h with almost no attenuation, confirming the good stability of this catalytic material.
[0068] Figure 8 It is demonstrated that after the stability test (tested for 100 h under the test conditions of a fixed current density of 500 mA cm -2 ), the electronic structure of the catalyst material is analyzed. From the XPS images before and after the test, it can be seen that the electronic structure of the sample WMo-CoP@NM obtained in Example 1 does not change significantly before and after the stability test, once again confirming the good stability of this catalytic material.
[0069] Figure 9Explanation: In Example 1, for the self-supported catalyst in simulated seawater alkaline solutions and real seawater alkaline solutions (collected from the Bohai Sea) with different concentrations, the performance difference of the catalyst is very small, demonstrating its potential for seawater electrolysis. (The linear sweep conditions are the same as Figure 5 the following).
[0070] Figure 10 Explanation: In real alkaline seawater (collected from the Bohai Sea), for the self-supported catalyst in Example 1, under the condition of a current density of 500 mA cm -2 , the water electrolysis reaction lasts for 100 h, and its performance decay is weak, verifying the good stability of this catalytic material.
[0071] Figure 11 Explanation: For the AWE stability test (using Example 1 as the cathode, NM as the anode, PPS as the diaphragm, temperature of 65 °C, and electrolyte of 30 wt% KOH), when the current density is 1.0 A cm -2 , the water electrolysis reaction exceeds 1500 h, and the voltage growth rate is only 0.076 mV h -1 , proving the commercial prospect of this catalytic material.
[0072] Figure 12 Explanation: By applying an intermittent and gradually increasing positive current to the cathode, before and after the test, the current density of the catalyst remains unchanged, demonstrating excellent reverse current resistance performance.
[0073] Figure 13 Explanation: For the accelerated degradation test (ADTs), maintain a current density of 0.4 A cm -2 for 10 minutes, then immediately switch to a higher current density (1.5 A cm -2 ), and then continue for another 10 minutes, without a shutdown step, and maintain 50 cycles (ADTs-1). After ADTs-1, the performance of the WMo-CoP@NM-based AWE system becomes better. Thereafter, maintain a current density of 0.4 A cm -2 for 10 minutes, then immediately switch to a higher current density (1.5 A cm -2 ), and then continue for another 10 minutes, maintain a 2-min shutdown step, and maintain 50 cycles (ADTs-2). After the ADTs test, the performance of the WMo-CoP@NM-based AWE system is still better than before the test.
[0074] Figure 14 Explanation: Using the electrodeposition technique, a catalyst material of 225 cm 2 is prepared by amplification, proving that this catalyst can achieve large-scale production.
[0075] Figure 15It is shown that the nine parts of the enlarged prepared catalyst material cut into 9 pieces of 5×5 cm all have excellent performance, proving that it is uniformly loaded on the nickel mesh, and the catalyst has high commercial applicability.
[0076] Through the above analysis, the present invention provides an industrial-grade alkaline water electrolyzer cathode catalyst suitable for fluctuating renewable energy. The catalyst has a super-hydrophilic structure, which can ensure the rapid penetration of the electrolyte and promote the continuous escape of bubbles, showing a low overpotential during the catalytic process. The present invention forms a stable amorphous catalyst on the nickel mesh by a simple one-step electrodeposition method, simplifies the preparation process, and improves the long-term stability of the catalyst. At the same time, the present invention realizes the adaptability of AWE technology to renewable energy, creates a strong and stable cathode with excellent anti-reverse current performance without additional protection current, and thus basically meets the requirements of AWE devices for intermittent and unpredictable renewable energy.
Claims
1. Preparation method of industrial-grade alkaline water electrolyzer cathode catalyst WMo-CoP@NM adapted to fluctuating renewable energy, characterized in that It includes the following steps: Mix a tungsten source, a cobalt source, a molybdenum source, a phosphorus source, an ammonium salt, and a citrate into a solution. Subsequently, place a nickel mesh (NM) into the solution and perform electrodeposition at room temperature. After the reaction ends, wash it several times with deionized water and ethanol, and dry it in an oven for standby.
2. The method according to claim 1, characterized in that In the step, the cobalt source is any one or more of various cobalt salts such as cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt carbonate, and cobalt fluoride; In the step, the tungsten source is any one or more of various tungsten salts and tungstates such as tungsten chloride, sodium tungstate, calcium tungstate, and ammonium tungstate; In the step, the molybdenum source is any one or more of various molybdates such as sodium molybdate, ammonium molybdate, calcium molybdate, zinc molybdate, molybdenum oxide, and molybdenum disulfide; In the step, the phosphorus source is any one or more of various hypophosphites, hypophosphates, and phosphates; In the step, the ammonium salt is any one or more of various ammonium salts such as ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate, and ammonium phosphate; In the step, the citrate is any one or more of various citrates such as sodium citrate, potassium citrate, and calcium citrate.
3. The method according to claim 1, wherein In the preparation step, CoCl2, WCl6, Na2MoO4, C6H5Na3O7, NH4Cl, and NaH2PO2 are dissolved in deionized water. For every 0.5 - 6 mmol of CoCl2, it corresponds to 50 ml of deionized water, 0.2 - 4 mmol of WCl6, 0.2 - 5 mmol of Na2MoO4, 0.5 - 5 mmol of C6H5Na3O7, 4 - 50 mmol of NH4Cl, and 2 - 40 mmol of NaH2PO2. After mixing evenly, it is put into the treated NM for electrodeposition; NM serves as the cathode, and under the condition of 5 - 200 mA cm -2 (preferably 25 - 100 mA cm -2 ), electrodeposition is carried out for 10 - 250 min, and after drying, WMo - CoP@NM is obtained.
4. The cathode catalyst for a water electrolyzer prepared by the method according to any one of claims 1-3.
5. Use of the cathode catalyst of the water electrolyzer prepared by the method according to any one of claims 1 to 3, characterized in that It is used for electrolyzing water under alkaline aqueous solution conditions and alkaline seawater conditions, and the concentrations of the alkaline aqueous solution and the alkaline seawater solution are 0.5-10M.
6. The application according to claim 5, characterized in that, In an AWE electrolytic cell with WMo-CoP@NM as the cathode, commercial nickel mesh as the anode, and PPS as the diaphragm, the stable current density during the operation of the electrolytic cell is 0.2 - 3.0 A cm -2 .
7. The application according to claim 5, wherein It has excellent reverse current resistance performance and can be unaffected by the oxidation effect of the forward current during the start-up and shutdown of the electrolytic cell. The fluctuating current density range during the operation of the electrolytic cell is 0 - 2.0 A / cm -2 .