Transition metal-based composite electrode for hydrogen production by alkaline electrolysis of water and preparation method of transition metal-based composite electrode

Abstract

The invention discloses a transition metal-based composite electrode for hydrogen production by alkaline electrolysis of water and a preparation method thereof, and the preparation method comprises the following steps: 1) uniformly dissolving a first transition metal salt and a second transition metal salt in the same organic alcohol respectively, and then mixing the two obtained salt-alcohol solutions to obtain a uniform and stable electro-deposition solution; and (2) a two-electrode system is adopted, the conductive substrate serves as a cathode, the cathode and an anode are immersed in the electrodeposition liquid for electrochemical deposition, then washing and drying are conducted, and the transition metal-based composite electrode evenly deposited with the binary alloy particle layer is obtained. According to the method, the single organic alcohol is selected as the electrode liquid solvent, and the front transition metal chlorate is selected as the solute, so that the introduction of the oxometallate is avoided, the direct conversion from the low-valence front transition metal ions to the rough alloy particle deposition layer is realized, the deposition energy consumption is effectively reduced, and the deposition efficiency is improved. And meanwhile, the catalyst has higher intrinsic hydrogen evolution activity and good mechanical strength and chemical stability, and is suitable for popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of electrocatalysis, and specifically relates to a transition metal-based composite electrode for producing hydrogen by alkaline water electrolysis and a preparation method thereof. Background Art

[0002] Hydrogen energy is a green and efficient secondary energy source, and it occupies a very important position in the diversified clean energy system. Currently, commercial alkaline electrolyzers mainly use nickel mesh as the cathode catalytic hydrogen production electrode. Although the nickel mesh electrode has low cost and good durability, its intrinsic catalytic activity is poor, resulting in low hydrogen production efficiency and high electricity consumption, which greatly increases the cost of hydrogen production by alkaline water electrolysis. Therefore, it is urgent to prepare transition metal-based catalytic electrodes with stronger intrinsic activity and high stability to promote the low-cost and large-scale application of hydrogen production by alkaline water electrolysis.

[0003] Studies have shown that due to the difference in 3d orbital electrons, there is an electronic complementarity effect between the early and late transition metals. The binary alloy material constructed based on this effect has a more optimized electronic orbital structure and can therefore exhibit stronger intrinsic hydrogen evolution activity. By constructing the above-mentioned binary alloy deposition layer on the surface of a conductive substrate by electrodeposition, it is expected to achieve both high intrinsic activity and high structural stability in the preparation of catalytic electrodes. For example, patent application CN202211656291.0 discloses a molybdenum-nickel alloy electrocatalyst, its preparation method, and its application in hydrogen production by electrolysis of water. By connecting nickel foam to the negative electrode of a constant current source and connecting a graphite rod to the positive electrode of the constant current source, the electrocatalyst is heated to 2.5 Acm in a solution containing Ni(NO3)2.6H2O, Na2MoO4.4H2O and NH4F. -2A composite catalytic electrode with a molybdenum-nickel alloy film grown on the nickel foam can be obtained by applying a constant current density of 120s. Patent application CN201910628403.3 discloses an electrodeposition method for preparing a nickel-molybdenum alloy foam. The electrodeposition solution used in the method includes nickel sulfate, sodium molybdate or potassium molybdate, sodium citrate, sodium chloride or potassium chloride or nickel chloride, ethanolamine, 1,4-butynediol, saccharin, and the pH value of the solution is adjusted to 8.5-9.5. The electrode obtained by electrodeposition has good catalytic activity. However, the above schemes are mainly based on aqueous solutions and ion conductor solutions. The types of solvents required for configuring the solution during electrodeposition are various and complex, and the process is cumbersome. Moreover, the pre-transition metals used in the above reports are generally metal oxoates, and the pre-transition metals are often present in the form of metal oxoates in aqueous solutions. At this time, the transition metals are in their highest valence state, and more electricity is required to reduce them during electrodeposition. At the same time, it is difficult to avoid the generation of bubbles during the deposition process by selecting an aqueous solution as the deposition liquid solvent, resulting in loose accumulation of the deposition layer, which seriously affects the stability of the electrode structure and is very easy to fall off during operation. Therefore, it is of great research significance and practical value to make reasonable improvements on the currently known methods of constructing early and late transition metal alloy electrodes by electrodeposition, optimize the selection of deposition solution, the selection of metal salt types and the adjustment of deposition conditions, and more efficiently construct transition metal-based composite electrodes with both high intrinsic activity and high stability. Summary of the invention

[0004] The main purpose of the present invention is to provide a transition metal-based composite electrode for hydrogen production by alkaline water electrolysis and a preparation method thereof, which has the characteristics of short deposition time and no auxiliary agent addition. The obtained binary alloy deposition layer exhibits a rough surface structure of particle accumulation, has a large exposed area, and can show significantly enhanced hydrogen evolution activity.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing a transition metal-based composite electrode for producing hydrogen by alkaline water electrolysis comprises the following steps:

[0007] 1) preparing an electrodeposition solution: dissolving a first transition metal salt and a second transition metal salt in the same organic alcohol respectively to obtain a first transition metal salt alcohol solution and a second transition metal salt alcohol solution respectively, and then mixing the obtained two salt alcohol solutions to obtain a uniform and stable electrodeposition solution;

[0008] 2) A two-electrode system is adopted, with a conductive substrate as the cathode, the cathode and the anode are immersed in an electrodeposition solution, electrochemical deposition is performed, and washing and drying are performed to obtain a transition metal-based composite electrode with a binary alloy particle layer uniformly deposited thereon.

[0009] In the above scheme, the selected first transition metal salt includes any one of chlorates, carbonates, sulfates, nitrates and acetates corresponding to the three metal elements Fe, Co and Ni. The selected second transition metal salt specifically refers to chlorides corresponding to the four metal elements Mo, V, Nb and W.

[0010] In the above scheme, the selected conductive substrate is one of nickel mesh, nickel sheet, nickel foam, titanium mesh, titanium sheet, carbon cloth, carbon paper, copper foam, graphene film, and copper sheet.

[0011] Preferably, the nickel mesh is a porous nickel mesh. The porous nickel mesh is prepared by pre-depositing a porous metal particle deposition layer on the surface of an ordinary smooth nickel mesh to construct a rough surface, which can better provide attachment sites for subsequent deposition and achieve a larger active exposure area.

[0012] In the above scheme, the concentrations of the first transition metal salt alcohol solution and the second transition metal salt alcohol solution are both 0.0004-0.2 mol / L.

[0013] Furthermore, the molar ratio of the first transition metal to the second transition metal in the electrodeposition solution is 1:(0.25-2).

[0014] Furthermore, the organic alcohol is one of methanol, ethanol and ethylene glycol, and the water content in the organic alcohol is required to be less than 0.02wt%.

[0015] In the above scheme, the conductive substrate needs to be pretreated, and the steps include: cutting the conductive substrate, ultrasonically cleaning it with acetone, ethanol, hydrochloric acid and water in sequence, and then drying it naturally.

[0016] In the above scheme, in the electrochemical deposition step, the applied voltage is 5-20V, and the corresponding current density is 0.001-0.05A cm -2 . The deposition time is 60-180s. The Ni / Co / Fe-Mo, Ni / Co / Fe-V, Ni / Co / Fe-Nb, and Ni / Co / Fe-W composite catalytic electrodes prepared according to the above scheme have a surface deposition layer composed of many fine alloy particles. The deposition layer thickness is 2-5μm, and the alloy particle size is about 50-200nm. Under the same area, the fine alloy particles are distributed more densely and in greater numbers, which can more effectively expose more high-efficiency active sites. At the same time, the catalytic layer obtained by electrodeposition has better density and stronger bonding with the substrate, which ensures the mechanical strength and chemical stability of the obtained electrode, making the obtained electrode have better stability.

[0017] The first transition metal referred to in the present invention mainly includes three metal elements, namely iron, cobalt and nickel, and their metal salts exist in the form of metal ions after dissolving in water. The second transition metal referred to in the present invention mainly includes four metal elements, namely molybdenum, vanadium, niobium and tungsten, and their metal salts exist in the form of metal oxoacid ions after dissolving in water, such as sodium molybdate, ammonium molybdate and the like.

[0018] The reaction principle of the present invention is:

[0019] On the basis of the conventional electrodeposition method to construct a binary alloy nanoparticle deposition layer, by selecting specific solvents and specific metal salts, the formation of metal oxoates is avoided, the types of deposition liquid additives are simplified, the power consumption of electrodeposition is reduced, and a more efficient alloy electrode construction is achieved. When the electrodeposition liquid is configured in a conventional aqueous solution, the second transition metal element often exists in the form of metal oxoates and is in its highest valence state +6. The current density during electrodeposition in the existing method is very high, and the power is greater in the same time, so a large amount of energy is required to reduce it to a single substance. The present invention achieves a lower valence state of Mo by combining a polar high-concentration organic alcohol (almost anhydrous) with a second transition metal chloride. 3+ 、V 3+ , Nb 5+ , W 5+ Stable dispersion of ions. Then a high voltage is applied to the entire electrodeposition system in a short time (60-180s). Since there are only metal ions and chloride ions in the electrodeposition solution of the present invention, there are no other side reactions during deposition, and the deposition speed is faster, and the uniformly dispersed first and second transition metal ions are quickly reduced to a binary alloy particle deposition layer with a smaller particle size.

[0020] It should be emphasized that the electrodeposition voltage and time need to be controlled during electrodeposition. If the voltage and time are below this range, it is impossible to obtain a good Ni / Co / Fe-Mo, Ni / Co / Fe-V, Ni / Co / Fe-Nb, Ni / Co / Fe-W alloy particle deposition layer. If the voltage and time are above this range, the metal deposition particles will be excessively accumulated, the bonding force between the deposition layers will be weakened, and the specific surface area will be reduced.

[0021] It should be emphasized that the organic alcohol used in the present invention is in anhydrous form. In a water environment, the second transition metal tends to exist in the form of metal oxoacid ions in its highest valence state. At the same time, water electrolysis reaction will occur, generating bubbles and consuming electricity.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) Compared with the traditional electrodeposition method, the present invention achieves Mo by adjusting the electrodeposition solute and solvent. 3+ 、V 3+ , Nb 5+ , W5+ The stable presence of second transition metal ions has a higher deposition efficiency compared with the reduction of high-valent metal oxoates.

[0024] (2) Compared with the traditional method of constructing alloy catalytic electrodes by electrodeposition, the present invention selects organic alcohol as solvent to avoid the influence of bubbles generated by electrolysis on the structural strength of the deposited layer. By setting a high voltage for a short time, alloy microcrystalline particles with smaller sizes can be obtained, which can expose more active sites.

[0025] (3) The method used in the present invention has a short preparation cycle, simple operation, strong repeatability, and is suitable for large-scale industrial production. It has good application prospects in the field of water electrolysis and hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the preparation process of Example 1 of the present invention;

[0027] Figure 2 This is a scanning electron microscope image of the final product prepared in Example 1 of the present invention;

[0028] Figure 3 This is a scanning electron microscope image of the thickness of the deposited layer of the final product prepared in Example 1 of the present invention;

[0029] Figure 4 The XRD pattern of the final product prepared in Example 1 of the present invention;

[0030] Figure 5 The electrochemical polarization curve of the final product prepared in Example 1 of the present invention is shown;

[0031] Figure 6 This is a scanning electron microscope image of the final product prepared in Comparative Example 1;

[0032] Figure 7 This is a scanning electron microscope image of the thickness of the deposited layer prepared in Comparative Example 1;

[0033] Figure 8 The electrochemical polarization curves of the final products prepared in Example 1 and Comparative Example 1 of the present invention are shown;

[0034] Fig. 9 This is a scanning electron microscope image of the final product prepared in Example 2 of the present invention;

[0035] Fig.10 This is the EDS image of the final product prepared in Example 2 of the present invention;

[0036] Fig.11 This is the electrochemical polarization curve diagram of the final product prepared in Example 2 of the present invention.

[0037] Fig.12This is a scanning electron microscope image of the final product prepared in Example 3 of the present invention;

[0038] Fig.13 This is the electrochemical polarization curve diagram of the final product prepared in Example 3 of the present invention.

[0039] Fig.14 This is a scanning electron microscope image of the final product prepared in Comparative Example 3;

[0040] Fig.15 This is the electrochemical polarization curve of the final product prepared in Comparative Example 3.

[0041] Fig.16 The electrochemical polarization curve of the final product prepared in Comparative Example 4;

[0042] Fig.17 This is the electrochemical polarization curve diagram of the final product prepared in Comparative Example 4.

[0043] Fig.18 This is a scanning electron microscope image of the final product prepared in Example 4 of the present invention;

[0044] Fig.19 This is the electrochemical polarization curve diagram of the final product prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] Example 1

[0047] A transition metal-based composite electrode for alkaline water electrolysis to produce hydrogen, the synthesis process diagram of which is shown in Figure 1 , the specific preparation method comprises the following steps:

[0048] 1) Prepare the electrodeposition solution: Disperse 0.01 mol NiCl2 and 0.0025 mol MoCl3 in 50 ml ethanol respectively, then mix the two salt-alcohol solutions evenly, stir slowly, and then place the mixed solution in a volumetric flask to make up the volume to obtain the electrodeposition solution for standby use;

[0049] 2) The treated copper sheet is used as the cathode and the platinum wire electrode is used as the anode. The positive and negative electrodes of a DC power supply are connected to the platinum wire electrode and the treated copper sheet respectively, and the electrodes are immersed in the electrodeposition solution; at room temperature, the deposition voltage is set to 20V, and the electrodeposition treatment is performed for 60s and 180s. After the deposition is completed, the obtained electrode is rinsed with deionized water and ethanol and dried naturally to obtain a transition metal-based NiMo alloy composite electrode.

[0050] The copper sheet treatment method is as follows: the copper sheet is cut into a standard size (2*2 cm), and then ultrasonically cleaned with acetone, ethanol, 3M hydrochloric acid, and deionized water in sequence, and then naturally dried for standby use.

[0051] Figure 2 The scanning electron microscope image of the NiMo alloy catalytic composite electrode obtained by electroplating a copper sheet in an ethanol deposition solution containing nickel salt and molybdenum salt. It can be found from the figure that when nickel salt and molybdenum salt are dissolved in ethanol to prepare a deposition solution, and a NiMo alloy deposition layer is constructed on the surface of the copper sheet by electrodeposition, a layer of alloy with fine particles is formed on the surface of the copper sheet. At this time, the particle size of the alloy particles obtained is about 50-200nm. The alloy catalytic electrode obtained by the electrodeposition scheme involved in the present invention shows a finer alloy particle structure and a significantly increased effective active area. At the same time, due to the presence of the NiMo alloy layer, the intrinsic activity of the electrode is further improved, which is conducive to the rapid transmission and diffusion of reactants and gas products.

[0052] Figure 3 The thickness of the electrodeposited layer of the NiMo alloy catalytic electrode obtained by electrodepositing the copper sheet in an ethanol deposition solution containing nickel salt and molybdenum salt. It can be seen from the figure that the thickness of the deposition layer is 2-3μm.

[0053] Figure 4 This is the XRD pattern of the NiMo alloy catalytic electrode obtained by electrodeposition of copper sheet in an ethanol deposition solution containing nickel salt and molybdenum salt.

[0054] Figure 5 The figure is an electrochemical polarization curve of the NiMo alloy catalytic electrode obtained by electroplating a copper sheet in an ethanol deposition solution containing nickel salt and molybdenum salt at room temperature with 1M KOH. It can be seen from the figure that loading a NiMo alloy metal deposition layer on the surface of the copper sheet can effectively improve the hydrogen evolution activity of the copper sheet electrode, and the electrode deposited with NiMo alloy particles on the surface of the copper sheet after optimizing the electroplating strategy of the present invention shows a lower hydrogen evolution overpotential. Under the conditions of 1M KOH and room temperature, the driving current is 500mAcm -2 The hydrogen evolution current (20V-3min) only requires 340mV overpotential. The results show that the NiMo alloy catalytic electrode prepared by our method has stronger hydrogen evolution activity, and this excellent performance is of great significance for practical industrial applications.

[0055] Comparative Example 1

[0056] A NiMo alloy catalytic electrode, the preparation method of which comprises the following steps:

[0057] 1) Prepare the electrodeposition solution: Disperse 0.01 mol NiCl2 and 0.0025 mol MoCl3 in 50 ml ethanol respectively, then mix the two salt-alcohol solutions evenly, stir slowly, and then place the mixed solution in a volumetric flask to make up the volume to obtain the electrodeposition solution for standby use;

[0058] 2) The treated copper sheet is used as the cathode and the platinum wire electrode is used as the anode. The positive and negative electrodes of a DC power supply are connected to the platinum wire electrode and the treated copper sheet respectively, and the electrodes are immersed in the electrodeposition solution. Under room temperature conditions, the deposition voltage is set to 20 V, and the deposition time is 300 s and 600 s. After the deposition, the obtained electrode is rinsed with deionized water and ethanol and dried naturally to obtain a NiMo alloy catalytic electrode.

[0059] Figure 6 This is a scanning electron microscope image of the electrode obtained in Comparative Example 1. It can be seen from the figure that when the time is too long, the metal particles are piled up due to the long time, the particle size is too large, the active area is reduced, and the hydrogen evolution performance is reduced.

[0060] Figure 7 The thickness of the electrodeposited layer of the NiMo alloy catalytic electrode obtained by electrodepositing the copper sheet in an ethanol deposition solution containing nickel salt and molybdenum salt. It can be seen from the figure that the thickness of the deposition layer is about 5μm. This shows that as the deposition time increases, the thickness of the electrodeposited layer becomes thicker, affecting its electrocatalytic performance.

[0061] Figure 8 The electrochemical polarization curves of the NiMo alloy catalytic electrode obtained by electrodeposition on a copper sheet at a deposition voltage of 20 V and deposition times of 60 s, 180 s, 300 s, and 600 s in 1 M KOH at room temperature.

[0062] Comparative Example 2

[0063] A method for preparing a NiMo alloy catalytic electrode comprises the following steps: 1) electrodeposition in a conventional aqueous solution to prepare an electrodeposition solution: 0.01 mol Ni(NO3)2·6H2O, 0.0025 mol Na2MoO4·4H2O and 1 mol NH4F are dispersed in 50 ml of deionized water, and then the mixed solution is placed in a volumetric flask for constant volume to obtain an electrodeposition solution for standby use.

[0064] 2) The treated copper sheet is used as the cathode and the platinum wire electrode is used as the anode. The positive and negative electrodes of the DC power supply are connected to the platinum wire electrode and the treated copper sheet respectively, and the electrodes are immersed in the electrodeposition solution. In the aqueous solution system, the current density is set to 2.5A / cm 2 , time is 180s, and NiMo alloy catalytic electrodes are deposited respectively.

[0065] The power consumption of the two systems was calculated respectively. In the ethanol system of Example 1, during electrodeposition, the voltage was 20V, the current was 0.08A, and the time was 180s. The power consumption was calculated to be 0.08kWh. In the aqueous solution, the current was 2.5A, the voltage was 13.05V, and the time was 180s. The power consumption was calculated to be 1.631kWh. Through the comparison of power consumption, it can be found that the present invention achieves the same performance as the traditional aqueous electrodeposition method, consumes less power, and is more economical in comparison.

[0066] Example 2

[0067] A transition metal-based composite electrode for producing hydrogen by alkaline water electrolysis, wherein the preparation method comprises the following steps:

[0068] 1) Prepare the electrodeposition solution: Disperse 0.01 mol NiCl2 and 0.01 mol MoCl3 in 50 ml ethanol respectively, then mix the two salt-alcohol solutions evenly, stir slowly, and then place the mixed solution in a volumetric flask to make up the volume to obtain the electrodeposition solution for standby use;

[0069] 2) The prepared porous nickel mesh is used as a cathode, the platinum wire electrode is used as an anode, the positive and negative electrodes of a DC power supply are connected to the platinum wire electrode and the porous nickel respectively, and the electrodes are immersed in an electrodeposition solution; at room temperature, the deposition voltage is set to 20 V, and the electrodeposition treatment is performed for 180 seconds. After the deposition is completed, the obtained electrode is rinsed with deionized water and ethanol and dried naturally to obtain a transition metal-based NiMo alloy catalytic electrode with porous nickel as a carrier.

[0070] The porous nickel mesh is prepared by uniformly dispersing 0.1 mol nickel chloride in 100 mL deionized water and adding 2 mol / L ammonium chloride to obtain an electrodeposition solution; an ordinary smooth nickel mesh is used as a cathode, a graphite sheet is used as an anode, and the electrodes are immersed in the electrodeposition solution; at room temperature, the deposition current is set to 3 A cm -2 , and an electrodeposition treatment was performed for 90 seconds to obtain a porous nickel mesh.

[0071] Fig. 9This is a scanning electron microscope image of a NiMo alloy catalytic electrode obtained by electrodeposition of a porous nickel mesh in an ethanol deposition solution containing nickel salt and molybdenum salt. It can be seen from the figure that a layer of fine alloy particles is formed on the surface of the porous nickel mesh. The particle size of the alloy particles obtained at this time is about 50nm-200nm. Due to the porous structure of the porous nickel, the effective active area is significantly increased. At the same time, due to the presence of the NiMo alloy layer, the intrinsic activity of the porous nickel electrode is further improved, which is conducive to the rapid transmission and diffusion of reactants and gas products.

[0072] Fig.10 This is the EDS image of the NiMo alloy particle layer deposited on the porous nickel surface. It can be seen that the Ni and Mo elements are evenly distributed on the surface, indicating that the NiMo alloy particle layer is uniformly deposited.

[0073] Fig.11 The electrochemical polarization curve of the electrode obtained in Example 2 at room temperature in 1 M KOH (where NM represents ordinary nickel mesh and PN represents porous nickel mesh).

[0074] Example 3

[0075] A transition metal-based composite electrode for producing hydrogen by alkaline water electrolysis, wherein the preparation method comprises the following steps:

[0076] 1) Prepare the electrodeposition solution: Disperse 0.01 mol NiCl2 and 0.01 mol VCl3 in 50 ml ethanol respectively, then mix the two salt-alcohol solutions evenly, stir slowly, and then place the mixed solution in a volumetric flask to make up the volume to obtain the electrodeposition solution for standby use;

[0077] 2) Use the treated nickel mesh as the cathode and the platinum wire electrode as the anode, connect the positive and negative electrodes of the DC power supply to the platinum wire electrode and the copper sheet respectively, and immerse the electrodes in the electrodeposition solution; at room temperature, set the deposition voltage to 5V, 10V, and 20V, respectively, and perform the electrodeposition treatment for 180s. After the deposition, rinse the obtained electrode with deionized water and ethanol and dry it naturally to obtain a NiV alloy catalytic electrode.

[0078] Fig.12 The scanning electron microscope image of the electrode obtained by the scheme described in Example 3. It can be seen from the figure that the surface of the copper sheet is evenly covered with a deposition layer formed by alloy particles with a particle size of about 50-200nm. On the particles of this alloy particle deposition layer, as the voltage increases, the particles gradually grow. It shows that by adjusting the voltage, the size of the alloy particles can be controlled, thereby achieving a deposition layer with a larger surface area.

[0079] Fig.13 The electrochemical polarization curve of the electrode obtained in Example 3 at room temperature in 1 M KOH.

[0080] Comparative Example 3

[0081] A NiV alloy catalytic electrode, the preparation method of which is substantially the same as that of Example 3, except that: the deposition time is set to 180s, the deposition voltage is set to 3V for the electrodeposition treatment, and after the deposition is completed, the obtained electrode is rinsed with deionized water and ethanol and dried naturally.

[0082] Fig.14 The scanning electron microscope image is the electrode obtained in comparative example 3. It can be seen from the figure that when the electrodeposition voltage is too low, there are fewer NiV alloy particles on the surface, the alloy particle deposition layer is also relatively smooth, and the obtained electrode performance is close to that of ordinary nickel mesh.

[0083] Fig.15 The electrochemical polarization curve of the electrode obtained in Comparative Example 3 at room temperature with 1M KOH is shown in the figure. It can be seen from the figure that when the electrodeposition voltage is too low, the performance of the obtained electrode is close to that of ordinary nickel mesh.

[0084] Comparative Example 4

[0085] A NiV alloy catalytic electrode, the preparation method of which is substantially the same as that of Example 3, except that: the deposition time is set to 180s, the deposition voltage is set to 40V for the electrodeposition treatment, and after the deposition is completed, the obtained electrode is rinsed with deionized water and ethanol and dried naturally.

[0086] Fig.16 The scanning electron microscope image of the electrode obtained in Comparative Example 4 is shown in FIG. 1 . As can be seen from the image, when the electrodeposition voltage is too high, there are too many NiV alloy particles on the surface, resulting in accumulation, a loose structure, and alloy particles are easy to fall off, and the performance is also reduced.

[0087] Fig.17 The electrochemical polarization curve of the electrode obtained in Comparative Example 4 at room temperature with 1M KOH is shown in the figure. As can be seen from the figure, when the electrodeposition voltage is too high, the performance of the obtained electrode is not as good as that of the electrode deposited at a voltage of 20V.

[0088] Example 4

[0089] A transition metal-based composite electrode for producing hydrogen by alkaline water electrolysis, wherein the preparation method comprises the following steps:

[0090] 1) Prepare electrodeposition solution: Disperse 0.01 mol NiCl2 and 0.0025 mol, 0.01 mol, and 0.02 mol NbCl3 in 50 ml ethanol respectively, then mix the two salt-alcohol solutions evenly, stir slowly, and then place the mixed solution in a volumetric flask to make up the volume, and obtain three different electrodeposition solutions of Ni:Nb=4:1, 1:1, and 1:2 for standby use;

[0091] 2) The prepared copper sheet is used as the cathode and the platinum wire electrode is used as the anode. The positive and negative electrodes of a DC power supply are connected to the platinum wire electrode and the copper sheet respectively, and the electrodes are immersed in the electrodeposition solution. Under room temperature conditions, the deposition time is set to 180s and the deposition voltage is set to 20V for the electrodeposition treatment. After the deposition is completed, the obtained electrode is rinsed with deionized water and ethanol and dried naturally.

[0092] Fig.18 The scanning electron microscope image of the electrode obtained in Example 4. It can be seen from the figure that when Ni:Nb=4:1, the alloy particles obtained by electrodeposition have a smaller size of 50-100nm. When Ni:Nb=1:2, the alloy particles obtained by electrodeposition have a smooth surface. When Ni:Nb=1:1, the alloy particles obtained by electrodeposition have a size of about 150-200nm, which proves that the alloy ratio also affects the size of the final deposited particles.

[0093] Fig.19 The electrochemical polarization curve of the electrode obtained in Example 4 at room temperature in 1M KOH is shown in the figure. It can be seen from the figure that when Ni:Nb=4:1, the obtained electrode has the best performance. 2 When , the overpotential is 375mV.

[0094] The above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here, so the obvious changes or modifications derived are still within the protection scope of the invention.

Claims

1. A method for preparing a transition metal-based composite electrode for producing hydrogen by alkaline water electrolysis, characterized in that: The following steps are involved: 1) preparing an electrodeposition solution: uniformly dissolving a first transition metal salt and a second transition metal salt in the same organic alcohol respectively to obtain a first transition metal salt alcohol solution and a second transition metal salt alcohol solution respectively, and then mixing the obtained two salt alcohol solutions to obtain a uniform and stable electrodeposition solution; 2) A two-electrode system is adopted, with a conductive substrate as the cathode, the cathode and the anode are immersed in an electrodeposition solution for electrochemical deposition, followed by washing and drying to obtain a transition metal-based composite electrode with a binary alloy particle layer uniformly deposited thereon.

2. The preparation method according to claim 1, characterized in that: The first transition metal salt includes any one of chlorates, carbonates, sulfates, nitrates and acetates corresponding to the three metal elements of iron, cobalt and nickel.

3. The preparation method according to claim 1, characterized in that: The second transition metal salt includes chlorides corresponding to four metal elements: molybdenum, vanadium, niobium, and tungsten.

4. The preparation method according to claim 1, characterized in that: The conductive substrate is one of nickel mesh, nickel sheet, foam nickel, titanium mesh, titanium sheet, carbon cloth, carbon paper, foam copper, graphene film, and copper sheet.

5. The preparation method according to claim 4, characterized in that: The nickel mesh is a porous nickel mesh.

6. The preparation method according to claim 1, characterized in that: The organic alcohol is one of methanol, ethanol or ethylene glycol, and the water content in the organic alcohol is less than 0.02wt%.

7. The preparation method according to claim 1, characterized in that: The molar ratio of the first transition metal to the second transition metal in the electrodeposition solution is 1:(0.25-2).

8. The preparation method according to claim 1, characterized in that: In the electrochemical deposition step, the applied voltage is 5-20V and the deposition time is 60-180s.

9. The preparation method according to claim 1, characterized in that: The concentrations of the first transition metal salt alcohol solution and the second transition metal salt alcohol solution are both 0.0004-0.2 mol / L.

10. A transition metal-based composite electrode prepared according to the preparation method according to any one of claims 1 to 9, characterized in that: It comprises a conductive substrate and an alloy particle deposition layer attached to the surface of the conductive substrate, wherein the thickness of the alloy particle deposition layer is 2-5 μm, and the size of the alloy particles is 50 nm-200 nm.

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