A Ni-Se-C hydrogen evolution electrode and its preparation method

Abstract

The present invention discloses a Ni‑Se‑C hydrogen evolution electrode and a preparation method thereof, belonging to the technical field of electrocatalytic hydrogen evolution. The Ni‑Se‑C hydrogen evolution electrode is composed of a conductive substrate and a Ni‑Se‑C coating electroplated on the surface of the conductive substrate. First, the conductive substrate is pretreated in the present invention; then, Ni, Se, and C elements are deposited on the pretreated conductive substrate by electroplating to form a Ni‑Se‑C hydrogen evolution electrode with excellent hydrogen evolution performance. The synthesis method of the present invention is simple and the catalytic layer structure is stable. The synthesized Ni‑Se‑C hydrogen evolution electrode can be widely applied to the industrial production of hydrogen by electrolyzing water, and has significant practical value and economic value.

Description

Technical Field

[0001] The present invention relates to a Ni - Se - C hydrogen evolution electrode, and particularly to a preparation method of the Ni - Se - C hydrogen evolution electrode. Background Art

[0002] Under the background of the carbon neutrality goal, coupling renewable energy for power generation to produce hydrogen can achieve the consumption of peak - valley electricity and the comprehensive application of distributed energy. As a bridge for the transition and conversion between fossil energy and renewable energy, hydrogen energy is expected to reduce carbon emissions during transportation and replace coke in the metallurgical industry to reduce carbon emissions. Electrolytic water hydrogen production is an industrial hydrogen production method with wide application and mature technology. However, due to factors such as high over - potential, electrolytic water hydrogen production usually consumes a large amount of electric energy, seriously hindering the large - scale application of this technology.

[0003] In recent years, developing low - cost non - precious metal electrocatalysts is an effective way to reduce the energy consumption of electrolytic water hydrogen production. Patent CN114703506A discloses a micro - spherical MnFe2O4 - supported nano - linear WS2 composite electrocatalytic hydrogen production catalyst and its preparation method. The catalyst synthesized by this method has a high specific surface area, thus having high hydrogen evolution performance. However, its preparation steps are cumbersome, and the synthesized catalyst material is a powder material, which needs to be loaded on the substrate material with an organic binder, reducing the charge transfer rate.

[0004] Patent CN115011995A discloses a cerium - based hydrogen evolution electrocatalyst and its preparation method and application. This patent has the advantage of simple operation. However, its hydrogen evolution over - potential is relatively high, making it difficult to meet the requirements of industrial electrolytic water hydrogen production. Summary of the Invention

[0005] Object of the Invention: One object of the present invention is to provide a Ni - Se - C hydrogen evolution electrode with high catalytic activity; another object of the present invention is to provide a preparation method of the above - mentioned hydrogen evolution electrode.

[0006] Technical Solution: The Ni - Se - C hydrogen evolution electrode described in the present invention is composed of a conductive substrate and a Ni - Se - C coating electro - deposited on the surface of the conductive substrate.

[0007] The electronic structure of Se atoms is 4s2 4 p 4 , where the energy level of the empty 3d orbital is very close to the 3s and 3p orbitals. Therefore, the 3d orbital of Se atoms is easy to combine with transition metal atoms to form covalent bonds, endowing it with more metallic properties, which is conducive to electron transfer and the occurrence of catalytic reactions; in addition, the addition of carbon atoms makes the grain size smaller, resulting in more active sites and accelerating the hydrogen evolution reaction.

[0008] Among them, in the Ni-Se-C coating, the mass percentage contents of the respective elements are: 40-60% Ni, 40-60% Se, and the balance is C.

[0009] Among them, the conductive substrate is a nickel foam substrate.

[0010] The preparation method of the above electrocatalytic hydrogen evolution electrode includes the following steps:

[0011] (1) First, prepare an electroplating aqueous solution, which is prepared by adding a nickel source, a selenium source, a carbon source, a buffer, and a conductive agent to water;

[0012] (2) Using the pretreated conductive substrate as the working electrode, a graphite sheet as the auxiliary electrode, and a saturated calomel electrode as the reference electrode, electro-deposit in the electroplating aqueous solution by electro-deposition method to obtain a Ni-Se-C coating on the surface of the conductive substrate.

[0013] Among them, in step (1), the nickel source is one or a mixture of several water-soluble nickel salts; the selenium source is one or a mixture of selenium dioxide, sodium selenite, and sodium selenate; the carbon source is one or a mixture of arginine, lysine, or histidine.

[0014] Among them, in step (1), the buffer is boric acid or ammonium chloride.

[0015] Among them, in step (1), the conductive agent is one or a mixture of NaCl, LiCl, or KCl.

[0016] Among them, in step (1), in the electroplating aqueous solution, the mass concentration of the nickel source is 20-40 g / L, the mass concentration of the selenium source is 5-20 g / L, the mass concentration of the carbon source is 2-5 g / L. The addition of the carbon source reduces the grain size of the coating, which leads to an increase in the active sites of the intergranular material / grain boundary and a decrease in the hydrogen evolution overpotential; the mass concentration of the buffer is 20-60 g / L, and the mass concentration of the conductive agent is 1-10 g / L.

[0017] Among them, in step (2), the electroplating deposition method is CV electro-deposition. During the CV electro-deposition process (which does not occur continuously within the potential range and there are interruptions during the cycle), porous deposits will be generated, increasing the contact area of the catalyst and accelerating the reaction rate; during the electro-deposition process, the temperature of the electroplating aqueous solution is 25-50 °C.

[0018] Among them, in step (2), the cyclic potential in CV electro-deposition is -2 to 0.4 V; the scanning speed is 2-10 mV / s; the number of cycles is 3-11. Under these process parameters, the obtained coating is uniform, the grains are fine, and the hydrogen evolution performance is excellent.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following remarkable effects: (1) The Ni-Se-C hydrogen evolution electrode synthesized by the present invention has a low hydrogen evolution overpotential and can be used as a hydrogen evolution electrode material for alkaline electrolytic water; (2) The present invention adopts the CV electrodeposition method, and the current direction can be periodically changed during the CV electrodeposition process. The sample to be plated becomes an anode for a part of the time in each cycle, thereby controlling the crystallization growth time so that it cannot grow very thick. In addition, the reasonable electroplating aqueous solution formula improves the polarization effect of the cathode, making the nucleation rate greater than the growth rate of the crystal nuclei, thereby obtaining a coating with fine crystallization, small grain size and uniform thickness; (3) Before the electrodeposition process, the oxide scale and organic matter on the surface of the substrate are removed by pretreatment first. In addition, the selection of good process parameters makes the coating evenly dispersed and tightly combined with the substrate, reducing the shedding phenomenon of the electrode material during the hydrogen evolution reaction process and greatly improving the stability of the electrode. Description of the Drawings

[0020] Figure 1 SEM image of the Ni-Se-C coating prepared in Example 1;

[0021] Figure 2 EDS spectrum of the Ni-Se-C coating prepared in Example 1;

[0022] Figure 3 Linear sweep voltammetry (LSV) curves of the Ni-Se-C hydrogen evolution electrodes prepared in Examples 1-3;

[0023] Figure 4 Linear sweep voltammetry (LSV) curves of the hydrogen evolution electrodes prepared in Example 1 and Comparative Examples 1-3. Detailed Description of the Invention

[0024] Example 1

[0025] The preparation method of the Ni-Se-C hydrogen evolution electrode of the present invention specifically includes the following steps:

[0026] (1) Pretreatment of the conductive substrate: Cut the nickel foam material into small rectangular pieces. First, ultrasonically oscillate the cut nickel foam material in absolute ethanol for 20 minutes for chemical degreasing, then rinse it with deionized water, then ultrasonically oscillate it in 10% by mass of dilute hydrochloric acid for 20 minutes to remove the oxide on the material surface, and finally rinse it with deionized water until the pH value of the rinsing water is neutral, and put it in a vacuum drying oven for storage for later use. The pretreatment is to remove the oxide scale and organic matter on the surface of the substrate to enhance the bonding force between the coating and the conductive substrate;

[0027] (2) Preparation of electroplating aqueous solution: Add NiSO4·6H2O, SeO2, lysine, NH4Cl and LiCl to deionized water to obtain the electroplating aqueous solution. In the electroplating aqueous solution, the mass concentration of each substance is: 30 g / L NiSO4·6H2O, 11 g / L SeO2, 4 g / L lysine, 26 g / L NH4Cl and 4 g / L LiCl; the pH value of the electroplating aqueous solution is 2 (precipitation occurs in alkaline conditions, and the electrocatalytic performance of the obtained coating is the best in strong acidic conditions);

[0028] (3) Use a three-electrode system to electrochemically deposit and prepare a Ni-Se-C hydrogen evolution electrode on an electrochemical workstation. Use nickel foam as the working electrode, a graphite sheet as the auxiliary electrode, and a saturated calomel electrode as the reference electrode. During the electroplating deposition process, the temperature of the electroplating aqueous solution is 30 °C; in the CV electroplating deposition, the cyclic potential is -1 to 0.2 V, the scanning speed in the CV electroplating deposition is 5 mV / s, and the number of cyclic loops in the CV electroplating deposition is 9; after the electroplating deposition is completed, take out the nickel foam, rinse it with distilled water until the pH of the residual liquid is neutral, and dry it at 70 °C for 12 h in a vacuum environment to finally obtain a Ni-Se-C hydrogen evolution electrode.

[0029] The morphology of the Ni-Se-C hydrogen evolution electrode prepared in Example 1 was analyzed using a scanning electron microscope. From Figure 1 it can be seen that the surface of the electrode prepared by CV electroplating deposition presents a uniform, dense and delicate structure with nanoparticles. The size of the nanoparticles is very small, which can provide abundant active sites. The existence of the cellular structure increases the specific surface area of the electrode, thus enabling the electrode to have high hydrogen evolution performance.

[0030] Figure 2 is the energy spectrum diagram of the Ni-Se-C coating. From Figure 2 it can be seen that Ni, C, and Se elements exist in the coating, and the atomic ratio of Ni:Se:C is 30.13:62.29:7.58 (atomic %).

[0031] Use an electrochemical workstation (Autolab, Metrohm China Co., Ltd., Switzerland) to test the electrochemical performance of the Ni-Se-C hydrogen evolution electrode prepared in Example 1 in a three-electrode system. Use the Ni-Se-C hydrogen evolution electrode as the working electrode, a graphite sheet as the auxiliary electrode, and SCE as the reference electrode. Use 1 mol / L KOH solution as the electrolyte, and test its hydrogen evolution linear sweep curve at a temperature of 25 °C and a scanning speed of 1 mV / s. The curve is as Figure 3 shown.

[0032] Example 2

[0033] The preparation method of the Ni-Se-C hydrogen evolution electrode of the present invention specifically includes the following steps:

[0034] (1) Pretreatment of the conductive substrate: Cut the nickel foam material into small rectangular pieces. First, ultrasonically oscillate the cut nickel foam material in absolute ethanol for 20 minutes for chemical degreasing, then rinse it thoroughly with deionized water. Next, ultrasonically oscillate it in 10% (by mass) dilute hydrochloric acid for 20 minutes to remove the oxide on the material surface. Finally, rinse it with deionized water until the pH value of the rinsing water is neutral, and place it in a vacuum drying oven for storage and later use;

[0035] (2) Preparation of the electroplating aqueous solution: Add NiSO4·6H2O, SeO2, lysine, NH4Cl, and LiCl to deionized water to obtain the electroplating aqueous solution. In the electroplating aqueous solution, the mass concentration of each substance is as follows: 30 g / L NiSO4·6H2O, 11 g / L SeO2, 3 g / L lysine, 26 g / L NH4Cl, and 4 g / L LiCl; the pH value of the electroplating aqueous solution is 2;

[0036] (3) Use a three-electrode system to electrochemically deposit and prepare the Ni-Se-C hydrogen evolution electrode on an electrochemical workstation. Use nickel foam as the working electrode, a graphite sheet as the auxiliary electrode, and a saturated calomel electrode as the reference electrode. During the electroplating deposition process, the temperature of the electroplating aqueous solution is 30 °C; in the CV electroplating deposition, the cyclic potential is -1 to 0.2 V, the scanning rate in the CV electroplating deposition is 5 mV / s, and the number of cyclic loops in the CV electroplating deposition is 9 loops; after the electroplating deposition is completed, take out the nickel foam, rinse it with distilled water until the pH of the residual liquid is neutral, and dry it at 70 °C for 12 h in a vacuum environment to finally obtain the Ni-Se-C hydrogen evolution electrode.

[0037] Use an electrochemical workstation (Autolab, Metrohm China Co., Ltd., Switzerland) to test the electrochemical performance of the Ni-Se-C hydrogen evolution electrode material prepared in Example 2 in a three-electrode system. Use the Ni-Se-C hydrogen evolution electrode as the working electrode, a graphite sheet as the auxiliary electrode, and an SCE as the reference electrode. Use 1 mol / L KOH solution as the electrolyte, at a temperature of 25 °C and a scanning rate of 1 mV / s, test its hydrogen evolution linear sweep curve, and the curve is as Figure 3 shown.

[0038] Example 3

[0039] The preparation method of the Ni-Se-C hydrogen evolution electrode of the present invention specifically includes the following steps:

[0040] (1) Pretreatment of the conductive substrate: Cut the nickel foam material into small rectangular pieces. First, ultrasonically oscillate the cut nickel foam material in absolute ethanol for 20 minutes for chemical degreasing, then rinse it thoroughly with deionized water. Next, ultrasonically oscillate it in 10% (by mass) dilute hydrochloric acid for 20 minutes to remove the oxide on the material surface. Finally, rinse it with deionized water until the pH value of the rinsing water is neutral, and place it in a vacuum drying oven for storage and later use;

[0041] (2) Preparation of electroplating aqueous solution: Add NiSO4·6H2O, SeO2, lysine, NH4Cl and LiCl to deionized water to obtain an electroplating aqueous solution. In the electroplating aqueous solution, the mass concentration of each substance is: 30 g / L NiSO4·6H2O, 11 g / L SeO2, 2 g / L lysine, 26 g / L NH4Cl and 4 g / L LiCl; the pH value of the electroplating aqueous solution is 2;

[0042] (3) Use a three-electrode system to electrochemically deposit and prepare a Ni-Se-C hydrogen evolution electrode on an electrochemical workstation. Use nickel foam as the working electrode, a graphite sheet as the auxiliary electrode, and a saturated calomel electrode as the reference electrode. The temperature of the electroplating aqueous solution during the electroplating deposition process is 30 °C; in the CV electroplating deposition, the cyclic potential is -1 to 0.2 V, the scanning rate in the CV electroplating deposition is 5 mV / s, and the number of cycles in the CV electroplating deposition is 9; after the electroplating deposition is completed, take out the nickel foam, rinse it with distilled water until the pH of the residual liquid is neutral, and dry it at 70 °C in a vacuum environment for 12 h to finally obtain a Ni-Se-C hydrogen evolution electrode.

[0043] Use an electrochemical workstation (Autolab, Metrohm China Co., Ltd., Switzerland) to test the electrochemical performance of the Ni-Se-C hydrogen evolution electrode material prepared in Example 2 in a three-electrode system. Use the Ni-Se-C hydrogen evolution electrode as the working electrode, a graphite sheet as the auxiliary electrode, and SCE as the reference electrode. Use 1 mol / L KOH solution as the electrolyte, at a temperature of 25 °C and a scanning rate of 1 mV / s, test its hydrogen evolution linear sweep curve, and the curve is as Figure 3 shown.

[0044] Comparative Example 1

[0045] The preparation method of the electrocatalytic hydrogen evolution material in Comparative Example 1 is basically the same as that in Example 1, and the only difference is that when preparing the electroplating aqueous solution in step (2), lysine is not added to the deionized water.

[0046] Comparative Example 2

[0047] The preparation method of the electrocatalytic hydrogen evolution material in Comparative Example 2 is basically the same as that in Example 1, and the only difference is that when preparing the electroplating aqueous solution in step (2), SeO2 is not added to the deionized water.

[0048] Comparative Example 3

[0049] The preparation method of the electrocatalytic hydrogen evolution material in Comparative Example 3 is basically the same as that in Example 1, and the only difference is that when preparing the electroplating aqueous solution in step (2), NiSO4·6H2O is not added to the deionized water.

[0050] Hydrogen evolution performance test of Ni - Se - C electrode: Using an electrochemical workstation (CHI600E, Beijing World Trade Far East Scientific Instruments Co., Ltd.), the electrochemical performance of the Ni - Se - C hydrogen evolution electrode materials prepared in Examples 1 - 3 was tested in a three - electrode system. The Ni - Se - C hydrogen evolution electrode material was used as the working electrode, a graphite sheet as the auxiliary electrode, and SCE as the reference electrode. Using 1 mol / L KOH solution as the electrolyte, at a temperature of 25 °C and a scanning rate of 2 mV / s, the linear sweep voltammetry curve of hydrogen evolution was tested. The electrode potential was corrected for reversible hydrogen electrode and impedance compensation. All potentials were obtained according to the following Nernst equation: E RHE = E SCE + 0.242 + 0.059pH - iR (where: i is the measured current, and R is the solution impedance). The hydrogen evolution performance test of the electrocatalytic hydrogen evolution materials in Comparative Examples 1 - 3 was the same as the above method.

[0051] The electrocatalytic hydrogen evolution materials prepared in Examples 1 - 3 and Comparative Examples 1 - 3 were respectively subjected to hydrogen evolution performance tests. The hydrogen evolution overpotentials (mV) obtained from the tests are shown in Table 1.

[0052] Table 1 Hydrogen evolution overpotential test table of electrocatalytic hydrogen evolution materials

[0053] <![CDATA[Current density (mA·cm -2 )]]> <![CDATA[10mA·cm -2 > <![CDATA[50mA·cm -2 > <![CDATA[100mA·cm -2 > Example 1 62 188 239 Example 2 90 215 265 Example 3 115 233 283 Comparative Example 1 180 276 354 Comparative Example 2 225 324 401 Comparative Example 3 213 311 387

[0054] As can be seen from Table 1, as the concentration of lysine in the plating solution decreases, the hydrogen evolution potential of the electrodes prepared in Examples 1 - 3 gradually increases, and the hydrogen evolution performance decreases. The main reason is that as the carbon concentration in the plating solution decreases, the carbon content in the coating will decrease, the grain size of the coating will increase accordingly, and the active sites of the inter - crystalline substance / grain boundary will decrease, resulting in an increase in the hydrogen evolution overpotential. The hydrogen evolution overpotentials of the Ni - Se - C electrodes prepared in Examples 1 - 3 are much lower than those of the electrocatalytic hydrogen evolution materials in Comparative Examples 1 - 3, indicating that the Ni - Se - C hydrogen evolution electrode of this application has excellent hydrogen evolution performance.

Claims

1. A Ni - Se - C hydrogen evolution electrode, characterized in that: It consists of a conductive substrate and a Ni-Se-C coating electroplated on the surface of the conductive substrate; in the Ni-Se-C coating, the atomic percentage of Ni is 30.13%, the atomic percentage of Se is 62.29%, and the atomic percentage of C is 7.58%; the conductive substrate is nickel foam; The preparation method of the above-mentioned Ni-Se-C hydrogen evolution electrode includes the following steps: (1) Pretreatment of the conductive substrate; (2) Preparation of the electroplating aqueous solution: Add NiSO4·6H2O, SeO2, lysine, NH4Cl, and LiCl to deionized water to obtain the electroplating aqueous solution. In the electroplating aqueous solution, the mass concentration of each substance is: 30 g / L NiSO4·6H2O, 11 g / L SeO2, 4 g / L lysine, 26 g / L NH4Cl, and 4 g / L LiCl; the pH value of the electroplating aqueous solution is 2; (3) Use a three-electrode system to electro-deposit a Ni-Se-C hydrogen evolution electrode on an electrochemical workstation. Use nickel foam as the working electrode, a graphite sheet as the auxiliary electrode, and a saturated calomel electrode as the reference electrode. The temperature of the electroplating aqueous solution during the electroplating deposition process is 30 °C; the cyclic potential in the CV electro-deposition is -1 to 0.2 V, the scanning speed in the CV electro-deposition is 5 mV / s, and the number of cycles in the CV electro-deposition is 9; after the electroplating deposition is completed, take out the nickel foam, rinse it with distilled water until the pH of the residual liquid is neutral, and dry it at 70 °C in a vacuum environment for 12 h to finally obtain the Ni-Se-C hydrogen evolution electrode.

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