Preparation method and application of pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst

Abstract

The invention discloses a preparation method and application of a pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst, and relates to the technical field of electro-catalysis. The copper-cobalt alloy phosphide hydrogen evolution catalyst is obtained by adopting electrolyte containing a copper source, a cobalt source, a phosphorus source and an inorganic fluoride complexing agent, taking foamed nickel as a working electrode and carrying out electro-deposition by utilizing a constant voltage method. On the basis of low cost and a simple synthesis method, the electronic structure of the catalyst is adjusted, and the electron transfer efficiency and the stability of active sites are improved, so that an excellent water electrolysis hydrogen evolution effect is realized, and a new solution is provided for the development of the field of clean energy.

Description

Technical Field

[0001] The invention relates to the technical field of electrocatalysis, and in particular to a preparation method and application of a pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst. Background Art

[0002] As a clean energy, hydrogen has attracted much attention due to its high energy density, zero carbon emissions and strong renewability. There are various methods for preparing hydrogen, among which water electrolysis is widely used due to its environmental friendliness and high efficiency. However, the slow kinetics of the hydrogen evolution reaction (HER) leads to a high overpotential, which has always been a key issue restricting its large-scale application. Therefore, the development of resource-rich and efficient electrocatalysts has become the key to achieving efficient hydrogen production.

[0003] Pt-based catalysts are the best choice for HER electrocatalysts, which usually only require an overpotential of about 40 mV to reach 10 mA cm -2 However, their overpotential at high current density is high, and their commercial applications are limited by their high cost and low durability. To solve this problem, researchers have turned their attention to transition metal-based electrocatalysts, which have attracted great interest from researchers due to their abundant resources, low cost, and catalytic performance comparable to that of precious metals.

[0004] Nickel, cobalt, and copper-based materials have unique advantages as transition metal-based electrocatalysts: 1. Rich active sites: They can provide more catalytic active sites, thereby improving catalytic efficiency; 2. High active surface area: By regulating the nanostructure, the specific surface area can be significantly increased, further improving the catalytic performance; 3. Fast electron transfer: The optimized electronic structure helps to accelerate electron transfer and promote hydrogen evolution reaction. At the same time, by changing the composition and structure of transition metal alloys, their electronic structure and coordination environment can be adjusted to optimize their catalytic performance.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a preparation method and application of a pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst to solve the problems existing in the above-mentioned prior art. By ensuring that the material has a low overpotential on the basis of low cost and simple synthesis method, excellent water electrolysis hydrogen evolution effect is achieved, thereby providing a new solution for the development of the clean energy field.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention is to provide a method for preparing a pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst, comprising the following steps:

[0009] The pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst is obtained by using an electrolyte containing a copper source, a cobalt source, a phosphorus source and an inorganic fluoride complexing agent, taking nickel foam as a working electrode and performing electrodeposition by a constant voltage method.

[0010] Furthermore, the electrodeposition voltage is -3.5 V to -4.0 V, and the deposition time is 20-40 min. More preferably, the deposition voltage is -4 V, and the deposition time is 30 min.

[0011] Furthermore, the molar ratio of copper to cobalt in the electrolyte is 1-5:30.

[0012] Furthermore, the molar ratio of phosphorus to fluorine is 1-5:9.

[0013] Furthermore, the copper source is CuSO4·5H2O, the cobalt source is Co(NO3)2·6H2O, and the phosphorus source is sodium hypophosphite.

[0014] Furthermore, the molar ratio of copper, cobalt, phosphorus and fluorine in the electrolyte is 0.1:3-6:7-14:63; preferably 0.1:3:7:63.

[0015] Furthermore, during the electrodeposition process, a graphite rod is used as a counter electrode.

[0016] The second technical solution of the present invention is to provide a pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst prepared by the above preparation method.

[0017] The surface microstructure of the pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst prepared by the invention presents a pine needle nanosheet composite shape.

[0018] More preferably, the present invention in situ grows copper and cobalt on a nickel foam substrate by electrodeposition, and the phosphorus source and inorganic fluoride in the electrolyte form a pine needle nanosheet composite microscopic morphology on the catalyst surface. This special pine needle nanosheet composite morphology has a higher specific surface area, exposing more active sites, allowing it to fully contact with the solution, while the interconnected nanosheets are conducive to the transmission of electrons, and the rod-like structure provides a faster path for electron transmission.

[0019] The third technical solution of the present invention is to provide the use of the above-mentioned pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst in hydrogen evolution by electrolysis of water.

[0020] The doping of phosphorus can optimize the electronic structure of the catalyst, improve the conductivity and hydrogen adsorption capacity, accelerate the electron transfer caused by lattice distortion, enhance the catalytic activity and stability, and improve the electrochemical performance. The pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst designed by the present invention has a strong hydrogen evolution performance, which is mainly due to the doping of phosphorus by electrodeposition.

[0021] Co in the electrodeposition process 2+ and Cu 2+ Because it carries a positive charge, it loses electrons at the cathode to form Co and Cu elements attached to the nickel foam. Hypophosphite, which is usually used as a phosphorus source, does not accumulate in large quantities on the cathode nickel foam because the hypophosphorous acid containing phosphorus elements carries a negative charge, so it forms phosphides with Co and Cu, but a small amount of residue is inevitably left at the cathode, so that it gains electrons to generate P atoms that enter the lattices of Co and Cu to form unsaturated coordination bonds. This unsaturated coordination bond can serve as a channel for electron transfer, regulate the local charge distribution and electronic structure, thereby improving the electron transfer efficiency of the catalyst, and can also improve the stability of the active sites, which effectively improves the catalytic performance of the catalyst.

[0022] The results show that the copper-cobalt alloy phosphide hydrogen evolution catalyst was sandwiched between the working electrode and the counter electrode, a graphite rod and a Hg / HgO electrode were used as the reference electrode. The reaction rate was 10 mA cm in 1 M KOH solution. -2 The overpotential required for the current density is only 70 mV.

[0023] The present invention discloses the following technical effects:

[0024] The present invention uniformly loads copper and cobalt elements on nickel foam by an electrodeposition method to form a copper-cobalt alloy, which provides more active sites for the reaction and is conducive to enhancing the adsorption of water molecules by the catalyst. At the same time, phosphorus doping is achieved by electrodeposition, and the composite micromorphology of pine needle nanosheets formed by deposition is evenly distributed on the nickel foam, which improves the uniformity of the catalysis. At the same time, during the deposition process, phosphorus atoms can enter the lattices of Co and Cu to form unsaturated coordination bonds, which regulates the electronic structure of the catalyst, improves its electron transfer efficiency and the stability of the active sites, and is conducive to the conduct of the hydrogen evolution reaction.

[0025] The preparation method of the invention is easy to operate, green and environmentally friendly, and when used as a hydrogen evolution catalyst, has the advantages of low overpotential, low cost, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 In the figure, (a)-(f) are low-magnification scanning electron microscope images of the catalysts of Example 2 of the present invention and Comparative Examples 1-5, respectively; (g)-(l) are high-magnification scanning electron microscope images of the catalysts of Example 2 of the present invention and Comparative Examples 1-5, respectively.

[0028] Figure 2 It is a comparison diagram of the linear sweep voltammetric curves of the catalysts prepared in Example 2 of the present invention and Comparative Examples 1-5.

[0029] Figure 3 The catalysts prepared in Example 2 of the present invention and Comparative Examples 1-5 were subjected to a current density of 10 mA·cm -2 Overpotential comparison diagram when .

[0030] Figure 4 Comparison of linear sweep voltammetric curves of copper-cobalt alloy phosphide hydrogen evolution catalysts with pine needle nanosheet composite morphology prepared in Examples 1-5 of the present invention.

[0031] Figure 5 The catalyst prepared in Example 1-5 of the present invention was subjected to a current density of 10 mA·cm -2 Overpotential comparison diagram when .

[0032] Figure 6 The overpotential variation diagram of the catalyst prepared in Example 2 of the present invention working at current densities of 10 mV and 50 mV for 12 hours respectively. DETAILED DESCRIPTION

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0035] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0036] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0037] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0038] Example 1

[0039] Step 1: Place nickel foam (2*3 cm 2 ) were ultrasonically treated in 4 M HCl, deionized water, and anhydrous ethanol for 20 min, respectively, and then placed in a vacuum drying oven and dried at 60 °C for 2 h.

[0040] Step 2: Weigh 0.873 g (3 mmol) Co(NO3)2·6H2O, 0.025 g (0.1 mmol) CuSO4·5H2O, 2.313 g (63mmol) NH4F and 0.742 g (7 mmol) NaH2PO2·H2O, put them into an electrolytic cell, add 50 mL of deionized water, put in a magnet, and stir on a magnetic stirrer for 20 min.

[0041] Step 3: Clamp the nickel foam obtained in step 1 on the platinum-carbon electrode clamp, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, place the electrolytic cell in a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0042] Step 4: Operate the electrochemical workstation, set the deposition method to constant voltage, the deposition time to 30 min, and the deposition voltage to -3.5 V.

[0043] Step 5: The product obtained in step 4 was rinsed with anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 h to finally obtain a copper-cobalt alloy phosphide hydrogen evolution catalyst.

[0044] Example 2

[0045] Step 1: Place nickel foam (2*3 cm 2 ) were ultrasonically treated in 4 M HCl, deionized water, and anhydrous ethanol for 20 min, respectively, and then placed in a vacuum drying oven and dried at 60 °C for 2 h.

[0046] Step 2: Weigh 0.873 g Co(NO3)2·6H2O, 0.025 g CuSO4·5H2O, 2.313 g NH4F, and 0.742 g NaH2PO2·H2O, put them into the electrolytic cell, add 50 mL deionized water, and stir for 20 min.

[0047] Step 3: Clamp the nickel foam obtained in step 1 on the platinum-carbon electrode clamp, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, place the electrolytic cell in a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0048] Step 4: Operate the electrochemical workstation, set the deposition method to constant voltage, the deposition time to 30 min, and the deposition voltage to -4 V.

[0049] Step 5: The product obtained in step 4 was rinsed with anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 h to finally obtain a copper-cobalt alloy phosphide hydrogen evolution catalyst.

[0050] Example 3

[0051] Step 1: Place nickel foam (2*3 cm 2 ) were ultrasonically treated in 4 M HCl, deionized water, and anhydrous ethanol for 20 min, respectively, and then dried in a vacuum drying oven at 60 °C for 2 h.

[0052] Step 2: Weigh 0.873 g Co(NO3)2·6H2O, 0.025 g CuSO4·5H2O, 2.313 g NH4F, and 0.742 g NaH2PO2·H2O, put them into the electrolytic cell, add 50 mL deionized water, and stir for 20 min.

[0053] Step 3: Clamp the nickel foam obtained in step 1 on the platinum-carbon electrode clamp, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, place the electrolytic cell in a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0054] Step 4: Operate the electrochemical workstation to set the deposition method to constant voltage, the deposition time to 30 min, and the deposition voltage to -4.5 V.

[0055] Step 5: The product obtained in step 4 was rinsed with anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 h to finally obtain a copper-cobalt alloy phosphide hydrogen evolution catalyst.

[0056] Example 4

[0057] Step 1: Place nickel foam (2*3 cm 2 ) were sequentially placed in 4 M HCl, deionized water, and anhydrous ethanol solutions for 20 min of ultrasonic treatment, and then placed in a vacuum drying oven at 60 °C for 2 h.

[0058] Step 2: Weigh 0.873 g Co(NiO3)2·6H2O, 0.025 g CuSO4·5H2O, 2.313 g NH4F, and 0.742 g NaH2PO2, put them into the electrolytic cell, add 50 mL deionized water, and stir for 20 min.

[0059] Step 3: clamp the nickel foam obtained in step 1 on the reference electrode, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, put the electrolytic cell into a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0060] Step 4: Operate the electrochemical workstation to set the deposition method to constant voltage, the deposition time to 20 min, and the deposition voltage to -4 V.

[0061] Step 5: The product obtained in step 4 was rinsed with anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 h to finally obtain a copper-cobalt alloy phosphide hydrogen evolution catalyst.

[0062] Example 5

[0063] Step 1: Place nickel foam (2*3 cm 2 ) were sequentially placed in 4 M HCl, deionized water, and anhydrous ethanol solutions for 20 min of ultrasonic treatment, and then placed in a vacuum drying oven at 60 °C for 2 h.

[0064] Step 2: Weigh 0.873 g Co(NO3)2·6H2O, 0.025 g CuSO4·5H2O, 2.313 g NH4F, and 0.742 g NaH2PO2·H2O, put them into the electrolytic cell, add 50 mL deionized water, and stir for 20 min.

[0065] Step 3: Clamp the nickel foam obtained in step 1 on the platinum-carbon electrode clamp, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, place the electrolytic cell in a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0066] Step 4: Operate the electrochemical workstation to set the deposition method to constant voltage, the deposition time to 40 min, and the deposition voltage to -4 V.

[0067] Step 5: The product obtained in step 4 is rinsed with anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 h to obtain a pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst.

[0068] Comparative Example 1

[0069] Step 1: Place nickel foam (2*3 cm 2 ) were sequentially placed in 4 M HCl, deionized water, and anhydrous ethanol solutions for 20 min of ultrasonic treatment, and then placed in a vacuum drying oven at 60 °C for 2 h.

[0070] Step 2: Weigh 0.873 g Co(NO3)2·6H2O, 0.025 g CuSO4·5H2O, and 2.313 g NH4F, put them into the electrolytic cell, add 50 mL deionized water, and stir for 20 min.

[0071] Step 3: Clamp the nickel foam obtained in step 1 on the platinum-carbon electrode clamp, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, place the electrolytic cell in a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0072] Step 4: Operate the electrochemical workstation to set the deposition method to constant voltage, the deposition time to 30 min, and the deposition voltage to -4 V.

[0073] Step 5: The product obtained in step 4 was rinsed with anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 h to finally obtain a copper-cobalt alloy hydrogen evolution catalyst.

[0074] Comparative Example 2

[0075] Step 1: Place nickel foam (2*3 cm 2 ) were sequentially placed in 4 M HCl, deionized water, and anhydrous ethanol solutions for 20 min of ultrasonic treatment, and then placed in a vacuum drying oven at 60 °C for 2 h.

[0076] Step 2: Weigh 0.873 g Co(NO3)2·6H2O, 2.313 g NH4F, and 0.742 g NaH2PO2·H2O, put them into the electrolytic cell, add 50 mL deionized water, and stir for 20 min.

[0077] Step 3: Clamp the nickel foam obtained in step 1 on the platinum-carbon electrode clamp, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, place the electrolytic cell in a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0078] Step 4: Operate the electrochemical workstation to set the deposition method to constant voltage, the deposition time to 30 min, and the deposition voltage to -4 V.

[0079] Step 5: The product obtained in step 4 is rinsed with anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 h to finally obtain a metal cobalt phosphide hydrogen evolution catalyst.

[0080] Comparative Example 3

[0081] Step 1: Place nickel foam (2*3 cm 2 ) were sequentially placed in 4 M HCl, deionized water, and anhydrous ethanol solutions for 20 min of ultrasonic treatment, and then placed in a vacuum drying oven at 60 °C for 2 h.

[0082] Step 2: Weigh 0.873 g Co(NO3)2·6H2O, 2.313 g NH4F, 0.025 g CuSO4·5H2O, and 1.68 g Na2S·9H2O into an electrolytic cell, add 50 mL deionized water, and stir for 20 min.

[0083] Step 3: Clamp the nickel foam obtained in step 1 on the platinum-carbon electrode clamp, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, place the electrolytic cell in a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0084] Step 4: Operate the electrochemical workstation to set the deposition method to constant voltage, the deposition time to 30 min, and the deposition voltage to -4 V.

[0085] Step 5: The product obtained in step 4 was rinsed with anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 h to finally obtain a copper-cobalt alloy sulfide hydrogen evolution catalyst.

[0086] Comparative Example 4

[0087] Step 1: Place nickel foam (2*3 cm 2 ) were sequentially placed in 4 M HCl, deionized water, and anhydrous ethanol solutions for 20 min of ultrasonic treatment, and then placed in a vacuum drying oven at 60 °C for 2 h.

[0088] Step 2: Weigh 0.873 g Co(NO3)2·6H2O, 2.313 g NH4F, and 0.025 g CuSO4·5H2O, put them into an electrolytic cell, add 50 mL of 0.1 g / L graphene solution, and stir for 20 min.

[0089] Step 3: Clamp the nickel foam obtained in step 1 on the platinum-carbon electrode clamp, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, place the electrolytic cell in a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0090] Step 4: Operate the electrochemical workstation to set the deposition method to constant voltage, the deposition time to 30 min, and the deposition voltage to -4 V.

[0091] Step 5: Rinse the product obtained in step 4 with anhydrous ethanol, and then place it in a vacuum drying oven at 60°C for 6 h to finally obtain a copper-cobalt carbide hydrogen evolution catalyst.

[0092] Comparative Example 5

[0093] Step 1: Place nickel foam (2*3 cm 2 ) were sequentially placed in 4 M HCl, deionized water, and anhydrous ethanol solutions for 20 min of ultrasonic treatment, and then placed in a vacuum drying oven at 60 °C for 2 h.

[0094] Step 2: Weigh 0.873 g Co(NO3)2·6H2O, 2.313 g NH4F, and 0.025 g CuSO4·5H2O, put them into the electrolytic cell, add 50 mL deionized water, and stir for 20 min.

[0095] Step 3: Clamp the nickel foam obtained in step 1 on the platinum-carbon electrode clamp, use the grinding rod as the counter electrode, and put it into the evenly stirred electrolyte obtained in step 2. At the same time, place the electrolytic cell in a magnetic stirrer, adjust the speed to 9 rpm and connect it to the electrochemical workstation.

[0096] Step 4: Operate the electrochemical workstation to set the deposition method to constant voltage, the deposition time to 30 min, and the deposition voltage to -4 V.

[0097] Step 5: Rinse the product obtained in step 4 with anhydrous ethanol, and then place it in a vacuum drying oven at 60 °C for 6 h.

[0098] Step 6: Place the product obtained in step 4 into the downstream of the porcelain boat, place 0.742 g NaH2PO2·H2O into the upstream, and then place the porcelain boat into a tubular furnace. In a nitrogen atmosphere, heat the temperature from room temperature to 350°C at a heating rate of 4°C / min, and maintain the temperature for 2 hours to finally obtain a copper-cobalt metal phosphide hydrogen evolution catalyst.

[0099] Figure 1 In the figure, (a)-(f) are low-magnification SEM images of Example 2 and Comparative Examples 1-5, respectively; (g)-(l) are high-magnification SEM images of the corresponding samples. Figure 1 As can be seen from (a) to (f), only the nickel foam in the copper-cobalt phosphide hydrogen evolution catalyst prepared in Example 2 has densely distributed and uniformly distributed supports ( Figure 1 (a)), which gives it a larger specific surface area, can expose more active sites, and fully contact with the electrolyte. In the other comparative examples, the loading on the surface of nickel foam is sparsely distributed, or too aggregated, resulting in fewer exposed active sites and thus poor catalytic performance ( Figure 1 (b)-(f)). At the same time, under the observation of a scanning electron microscope with a larger magnification, it can be clearly seen that the copper-cobalt phosphide hydrogen evolution catalyst prepared in Example 2 is a composite morphology of pine needle nanosheets ( Figure 1 (g)), in Comparative Example 1, no P element doping was performed, and the prepared Cu-Co alloy catalyst showed micron spheres and pine needle rod structures ( Figure 1 (h)), and the exposed active sites of such microspheres are limited compared with nanosheets, so the catalytic performance is poorer than that of Example 2. In Comparative Example 2, no Cu element was introduced, and the prepared catalyst only showed a microsphere morphology ( Figure 1 (i)). Similarly, in Comparative Examples 3 and 4, S and C were used to replace P doping, respectively, and the samples prepared did not have any advantageous morphology, but also produced micron-spherical morphology ( Figure 1 (j) and (k)). In the catalyst prepared in Comparative Example 5, which also co-doped Co with P and Cu, the micron-spherical morphology disappeared and was replaced by a pine needle rod-like structure ( Figure 1(l)), which proves the positive effect of the co-doping of P and Cu elements to Co on the regulation of catalyst morphology. However, in comparative example 5, P doping is achieved by chemical vapor deposition, which forms a Co-P bond with metal Co, and the large-scale formation of Co-P bonds will affect the conductivity of the catalyst. At the same time, due to the rapid growth of the pine needle-like morphology at high temperature, the micron-shaped balls also shrink rapidly into rods, which is not conducive to the transfer of electrons, and thus has a negative impact on the performance of the catalyst. In Example 5, P doping is carried out by the strategy of electrodeposition, which makes the hypophosphite containing a large amount of P elements gather at the anode, while only a small amount of hypophosphite at the cathode is reduced to P atoms, entering the lattice of Co to form unsaturated coordination bonds, and the reaction is carried out at room temperature. The pine needle-like morphology is slowly formed, causing the micron-shaped balls to shrink into nanosheets, which provides a faster channel for electron transfer and greatly improves the catalytic performance. At the same time, during the electrodeposition process, the electrolyte is continuously stirred, which makes the load distribution on the surface of the nickel foam more uniform. The above all prove the advantages of the pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst prepared by electrodeposition.

[0100] The pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst prepared in the embodiment of the present invention was tested for electrochemical performance using a three-electrode system on a CHI760E electrochemical workstation. The test conditions were 1 mol / L KOH as the electrolyte, the prepared catalyst as the working electrode, the graphite rod as the counter electrode, and the reference electrode as Hg / HgO.

[0101] Figure 2 The linear sweep voltammetric curves of the catalysts prepared in Example 2 of the present invention and in Comparative Examples 1-5 are compared. It can be seen from the figure that at 40 mA·cm -2 At a current density of , the pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst prepared in Example 2 still has an extremely low overpotential of 168 mV.

[0102] Figure 3 The catalysts prepared in Example 2 and Comparative Examples 1-5 were subjected to a current density of 10 mA·cm -2 The overpotential comparison at the time of 200 ℃ and 200 ℃ shows that Example 2 is the most excellent, with an overpotential of only 70 mV. This is consistent with the results obtained from the scanning electron microscope image.

[0103] Figure 4 The linear sweep voltammetric curves of the copper-cobalt alloy phosphide hydrogen evolution catalysts with pine needle nanosheet composite morphology prepared in Examples 1-5 of the present invention are compared. It can be seen from the figure that different deposition voltages and deposition times will also affect the performance of the catalyst. At 100 mA·cm -2 At a current density of , the pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst prepared in Example 2 still has an extremely low overpotential of 141 mV.

[0104] Figure 5 The catalyst prepared in Example 1-5 was subjected to a current density of 10 mA·cm -2 As shown in the figure, different deposition potentials and deposition times have lower overpotentials, among which Example 2 is the best with an overpotential of only 70 mV, followed by Example 3 with an overpotential of 79 mV.

[0105] Figure 6 The overpotential change diagrams of the catalyst prepared in Example 2 when working for 12 h at current densities of 10 mV and 50 mV respectively show that the overpotential has not changed significantly, proving that the catalyst can work stably for 12 h.

[0106] Pt / C catalyst at 10 mA·cm -2 The overpotential is 40 mV at a current density of 100 mA·cm -2 The overpotential at the current density is 192 mV. The catalyst of the present invention has a better hydrogen evolution effect. Figure 5 As shown, the catalyst prepared in Example 2 has a -2 At the current density, its overpotential is close to that of Pt / C catalyst, which only needs 70 mV. Figure 4 As shown, at a larger current density such as 100 mA·cm -2 Its overpotential is even lower than that of Pt / C catalyst, which is only 141 mV. At the same time, its stability is tested, such as Figure 6 As shown, the catalysts prepared in Example 2 were -2 and 50 mA·cm -2 The catalyst can work stably for 12 hours at the current density 100 nm, which proves that the pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst prepared in Example 2 of the present invention has good stability, which is conducive to its industrial utilization.

[0107] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst, characterized in that: The following steps are involved: The pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst is obtained by using an electrolyte containing a copper source, a cobalt source, a phosphorus source and an inorganic fluoride complexing agent, taking nickel foam as a working electrode and performing electrodeposition by a constant voltage method.

2. The preparation method according to claim 1, characterized in that: The deposition voltage of the electrodeposition is -3.5 V to -4.0 V, and the deposition time is 20 to 40 minutes.

3. The preparation method according to claim 2, characterized in that: The deposition voltage of the electrodeposition is -4.0 V, and the deposition time is 30 min.

4. The preparation method according to claim 1, characterized in that: The molar ratio of copper to cobalt in the electrolyte is 1-5:

30.

5. The preparation method according to claim 1, characterized in that: The molar ratio of phosphorus to fluorine in the electrolyte is 1-5:

9.

6. The preparation method according to claim 1, characterized in that: The molar ratio of copper, cobalt, phosphorus and fluorine in the electrolyte is 0.1:3-6:7-14:

63.

7. The preparation method according to claim 1, characterized in that: The copper source is CuSO4·5H2O, the cobalt source is Co(NO3)2·6H2O, and the phosphorus source is NaH2PO2·H2O.

8. The preparation method according to claim 1, characterized in that: During the electrodeposition process, a graphite rod is used as a counter electrode.

9. A pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the pine needle nanosheet composite copper-cobalt alloy phosphide hydrogen evolution catalyst as claimed in claim 9 in hydrogen evolution by electrolysis of water.

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