Preparation method of low-load precious metal platinum-nickel catalyst and application of catalyst in hydrogen production from natural seawater

Abstract

The invention discloses a preparation method of a low-load precious metal platinum-nickel catalyst and application of the low-load precious metal platinum-nickel catalyst in hydrogen production from natural seawater, and belongs to the technical field of preparation of precious metal nano catalytic materials. According to the catalyst, foamed nickel serves as a carrier and is put into a potassium chloroplatinate solution to be subjected to a hydrothermal reaction, and the low-loading-capacity precious metal platinum-nickel catalyst is obtained. And assembling a flow type electrolytic tank, taking the obtained low-load noble metal platinum-nickel catalyst as a cathode of the flow type electrolytic tank, taking NiFe-LDH as an anode of the flow type electrolytic tank, taking natural seawater as an electrolyte of the cathode, taking a potassium hydroxide solution as an electrolyte of the anode, and carrying out an electro-catalytic reaction. The synthesis strategy of the nickel-based catalyst has the advantages of being easy and convenient to operate, low in cost, environmentally friendly and the like, the adopted raw materials are easy to obtain and accord with the green chemistry principle, the feasibility of large-scale production is achieved, and the nickel-based catalyst has wide application prospects in the fields of clean energy conversion and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen production by electrolysis of water, and particularly relates to a preparation method of a low-loading noble metal platinum-nickel catalyst and application thereof in hydrogen production from natural seawater. BACKGROUND

[0002] Among various new energy technologies, hydrogen production by electrolysis of water is continuously developing and has broad prospects. The reaction process of electrolysis of water includes two key half-reactions: oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). However, due to the slow kinetics of water splitting, this greatly limits the process of industrial application of electrolysis of water, and therefore, electrocatalysts play a crucial role in energy conversion technology. Noble metal-based catalysts (such as Pt, RuO2 and IrO2) are usually used as catalysts in industrial production of water splitting, but due to the limited reserves and high cost of these noble metals, their large-scale promotion is hindered.

[0003] In order to solve the problem of high cost of high-loading noble metal catalysts, it is of important research value and practical significance to develop low-loading noble metal catalysts with low cost and high activity. However, the mature water electrolysis technology at present, whether it is an alkaline electrolyzer or a proton exchange membrane (PEM) based electrolyzer, is based on high-purity water as raw material. If the energy required for the production of electrolysis of water in the near future, it will face problems such as freshwater distribution and resource shortage. In contrast, seawater accounts for 96.5% of the earth's water reserves, which is an almost unlimited resource and natural electrolyte raw material. However, due to the complexity of natural seawater, direct seawater splitting is still in its infancy.

[0004] The main reason for the stagnation of the progress of direct seawater electrolysis technology is the extremely low efficiency and poor stability of the electrolysis system under near-neutral conditions. More importantly, there are high concentrations of harmful chloride ions and unnecessary cations. Compared with alkalized water, the catalyst activity of anode oxygen evolution reaction (OER) and cathode hydrogen evolution reaction (HER) is very low under neutral seawater conditions. Therefore, a much higher applied voltage is required to obtain the required current density in actual operation. The electrolyzer with asymmetric feed (natural seawater is fed to the cathode and alkaline solution is fed to the anode) can effectively solve the competition reaction and corrosion of high concentration of harmful chloride ions in natural seawater. However, the catalyst for hydrogen production by electrolysis of natural seawater at the cathode still faces the problems of low electrolysis efficiency and poor stability.

[0005] The application is designed to solve the above technical problems, and a preparation method of a low-loading noble metal platinum-nickel catalyst and application thereof in hydrogen production from natural seawater. SUMMARY

[0006] In view of the defects and shortcomings of the prior art, the present application provides a preparation method of a low-loading noble metal platinum nickel catalyst and its application in hydrogen production from natural seawater. The present application aims to solve the technical problems of high overpotential, poor stability and poor corrosion resistance of existing hydrogen evolution catalysts. The Pt / Ni(OH)2 catalyst grown in situ on the foam nickel is prepared by using a one-step hydrothermal method. The flow-type electrolytic cell is assembled, and the prepared electrocatalyst is used as the cathode to carry out electrocatalytic reaction in natural seawater, which has high catalytic efficiency and stability.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a preparation method of a low-loading noble metal platinum nickel catalyst and its application in hydrogen production from natural seawater, comprising the following steps:

[0008] S1, pretreating the foam nickel substrate;

[0009] S2, weighing potassium chloroplatinate in a beaker, adding deionized water, stirring to form a uniform solution;

[0010] S3, transferring the uniform solution obtained in step S2 into the inner liner of the reaction kettle, putting the pretreated foam nickel obtained in step S1 into the oven for hydrothermal reaction, taking out, washing and drying after the reaction to obtain the low-loading noble metal platinum nickel catalyst;

[0011] S4, using the low-loading noble metal platinum nickel catalyst obtained in step S3 for electrolysis of natural seawater to produce hydrogen, using the low-loading noble metal platinum nickel catalyst as the cathode of the flow cell and using the NiFe-LDH catalyst as the anode of the flow cell, carrying out electrocatalytic reaction at 60℃, hydrogen is produced by hydrogen evolution reaction at the cathode, and oxygen is produced by oxygen evolution reaction at the anode.

[0012] On the basis of the above technical scheme, in step S1, the pretreatment of the foam nickel substrate is specifically as follows: first, immerse the foam nickel substrate in hydrochloric acid and ultrasonically treat it to remove the oxide film on the surface; then ultrasonically treat the foam nickel substrate in deionized water to remove residual hydrochloric acid, then ultrasonically treat it in ethanol, and then vacuum dry to complete the pretreatment of the foam nickel substrate.

[0013] On the basis of the above technical scheme, the size of the foam nickel is 30 mm*20 mm*1.6 mm; the concentration of the hydrochloric acid is 2-3 mol·L -1 ; the ultrasonic treatment time of the hydrochloric acid is 15-20 min, the ultrasonic treatment time of the deionized water is 10-15 min, and the ultrasonic treatment time of the ethanol is 5-10 min.

[0014] On the basis of the above technical scheme, in step S2, the mass of potassium chloroplatinate weighed is 10 mg, and the volume of deionized water is 20 ml.

[0015] On the basis of the above technical solution, in step S3, the temperature of the hydrothermal reaction is 100℃, the holding time is 2h, and the heating rate is 2℃·min -1 .

[0016] On the basis of the above technical solution, in step S4, the area of the cathode and the anode catalyst is 2 cm 2 .

[0017] On the basis of the above technical solution, in step S4, the cathode electrolyte of the flow cell is natural seawater, and the anode electrolyte is a 1 mol·L -1 -1 solution of potassium hydroxide.

[0018] In a second aspect, the application provides a low-loading noble metal platinum-nickel catalyst prepared by the above preparation method.

[0019] In a third aspect, the application provides the use of a low-loading noble metal platinum-nickel catalyst prepared by the above preparation method in the production of hydrogen from natural seawater.

[0020] Compared with related technologies, the application has the following advantages:

[0021] (1) The application synthesizes an ultra-low-loading noble metal Pt supported non-noble metal Ni-based catalyst Pt / Ni(OH)2 with oxygen affinity by one-step hydrothermal method. The catalyst uses nickel hydroxide with oxygen affinity as a substrate to achieve ultra-low-loading of noble metal Pt. The catalyst system exhibits excellent performance in the electrocatalytic electrolysis of natural seawater. The unique ultrathin nanosheet structure can significantly increase the exposure of active sites and optimize the contact between the catalyst and water molecules, thereby greatly improving the intrinsic catalytic activity and providing a high-activity, low-cost electrocatalyst for the electrolysis of natural seawater to produce hydrogen.

[0022] (2) The Pt / Ni(OH)2 catalyst prepared by the application effectively regulates the electronic structure of the Pt active center through Ni, optimizes the adsorption behavior of water molecules on the catalyst surface, and promotes the in-situ generation of hydroxyl radicals (*OH) under neutral conditions, which not only significantly improves the reaction selectivity of the catalyst system, but also enhances the corrosion resistance and anti-poisoning ability of the catalyst in natural seawater. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only one embodiment of the application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of the provided drawings.

[0024] Figure 1 is a flow chart of the method for electrolyzing natural seawater to produce hydrogen by using the low-loading noble metal platinum nickel catalyst provided by the present application;

[0025] Figure 2 is a scanning electron microscope photo of Pt / Ni(OH)2 prepared in Example 1 of the present application;

[0026] Figure 3 is an XPS spectrum of Pt / Ni(OH)2 prepared in Example 1 of the present application;

[0027] Figure 4 is a LSV test graph of Example 1 and Comparative Example 1 of the present application in a flow cell;

[0028] Figure 5 is a LSV test graph of Comparative Examples 1-3 of the present application in a flow cell;

[0029] Figure 6 is a continuous electrolysis graph of Example 1 of the present application in a flow cell at a current density of 0.5 A·cm -1

[0030] Figure 7 is a scanning electron microscope photo of Example 1 of the present application after electrolyzing seawater;

[0031] Figure 8 is a Raman spectrum of Example 1 of the present application before and after electrolyzing seawater; DETAILED DESCRIPTION

[0032] The present application will be further described below in conjunction with the accompanying drawings and examples:

[0033] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0034] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms “mounting”, “connecting”, “connection” should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] ​In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0036] The experimental methods used in the following examples are conventional methods unless otherwise specified.

[0037] The materials, reagents and the like used in the following examples can be obtained from commercial channels unless otherwise specified.

[0038] A preparation method of a low-loading noble metal platinum nickel catalyst and its application in hydrogen production from natural seawater, characterized in that the preparation method comprises the following steps:

[0039] S1, pretreating the foamed nickel substrate;

[0040] S2, weighing potassium chloroplatinate in a beaker, adding deionized water, stirring to form a uniform solution;

[0041] S3, transferring the uniform solution obtained in step S2 into the inner liner of the reaction kettle, placing the pretreated foamed nickel obtained in step S1, placing it in an oven for hydrothermal reaction, taking it out, washing and drying after the end to obtain the low-loading noble metal platinum nickel catalyst;

[0042] S4, using the low-loading noble metal platinum nickel catalyst obtained in step S3 for electrolysis of natural seawater to produce hydrogen, using the low-loading noble metal platinum nickel catalyst as the cathode of the flow cell, using the NiFe-LDH catalyst as the anode of the flow cell, and performing electrocatalytic reaction at 60℃, hydrogen is produced by hydrogen evolution reaction at the cathode, and oxygen is produced by oxygen evolution reaction at the anode.

[0043] On the basis of the above technical solution, in step S1, the pretreatment of the foamed nickel substrate is specifically as follows: first, immerse the foamed nickel substrate in hydrochloric acid and ultrasonically treat it to remove the oxide film on its surface; then ultrasonically treat the foamed nickel substrate in deionized water to remove residual hydrochloric acid, then ultrasonically treat it with ethanol, and then vacuum dry it to complete the pretreatment of the foamed nickel substrate.

[0044] On the basis of the above technical solution, the size of the foamed nickel is 30 mm*20 mm*1.6 mm; the concentration of the hydrochloric acid is 2-3 mol·L -1The ultrasonic treatment time for hydrochloric acid is 15-20 min, for deionized water it is 10-15 min, and for ethanol it is 5-10 min. Preferably, the concentration of the hydrochloric acid solution is 3 mol·L⁻¹. -1 The sonication time for hydrochloric acid was 15 min, for deionized water it was 10 min, and for ethanol solution it was 5 min.

[0045] Based on the above technical solution, in step S2, the mass of potassium chloroplatinate weighed is 10 mg, and the volume of deionized water is 20 ml.

[0046] Based on the above technical solution, in step S3, the hydrothermal reaction temperature is 100℃, the holding time is 2h, and the heating rate is 2℃·min. -1 .

[0047] Based on the above technical solution, in step S4, the area of ​​both the cathode and anode catalysts is 2 cm². 2 .

[0048] Based on the above technical solution, in step S4, the cathode electrolyte of the flow cell is natural seawater, and the anolyte is 1 mol·L⁻¹. -1 A potassium hydroxide solution.

[0049] Secondly, the present invention provides a low-loading noble metal platinum-nickel catalyst prepared by the above preparation method.

[0050] Thirdly, the present invention provides an application of a low-loading noble metal platinum-nickel catalyst prepared according to the above preparation method in the production of hydrogen from natural seawater.

[0051] Example 1

[0052] S1. Place nickel foam with dimensions of 30 mm * 20 mm * 1.6 mm sequentially into a 3 mol·L⁻¹ solution. -1 The pretreated nickel foam was ultrasonically treated for 15 min in hydrochloric acid solution, 10 min in deionized water and 5 min in anhydrous ethanol solution, and then placed in a vacuum drying oven at 60°C for 6 h to obtain pretreated nickel foam.

[0053] S2. Weigh 20 mg of potassium chloroplatinate into a beaker, add 20 ml of deionized water, and stir to form a homogeneous solution.

[0054] S3. Transfer the homogeneous solution obtained in step S2 to the lining of the reactor, place the pretreated nickel foam obtained in step S1 inside, and put it in an oven for hydrothermal reaction. The hydrothermal reaction temperature is 100℃, the holding time is 2 h, and the heating rate is 2℃·min. -1, and after the end, taking out, washing, drying to obtain the low-loading noble metal platinum nickel catalyst;

[0055] S4, the low-loading noble metal platinum nickel catalyst obtained in step S3 is used for electrolysis of natural seawater to produce hydrogen in a flow cell, the low-loading noble metal platinum nickel catalyst is used as the cathode of the flow cell, the NiFe-LDH catalyst is used as the anode of the flow cell, the catalyst area is 2 cm 2 , the catholyte of the flow cell is natural seawater, the anolyte is a 1 mol·L -1 solution of potassium hydroxide, and the electrocatalytic reaction is carried out at 60 DEG C, hydrogen is generated by the hydrogen evolution reaction at the cathode, and oxygen is generated by the oxygen evolution reaction at the anode.

[0056] Comparative Example 1

[0057] The method of this example is the same as that of Example 1, and the same parts are omitted. The difference between this example and Example 1 is that the temperature of the electrocatalytic reaction in step S4 is 25 DEG C.

[0058] Comparative Example 2

[0059] The difference between the method of this example and that of Comparative Example 1 is that a commercial platinum-carbon catalyst is used as the cathode of the flow cell, and the NiFe-LDH catalyst is used as the anode of the flow cell in step S4, and the catalyst area is 2 cm 2 , the catholyte of the flow cell is natural seawater, the anolyte is a 1 mol·L -1 solution of potassium hydroxide, and the electrocatalytic reaction is carried out at 25 DEG C, hydrogen is generated by the hydrogen evolution reaction at the cathode, and oxygen is generated by the oxygen evolution reaction at the anode.

[0060] Comparative Example 3

[0061] The difference between the method of this example and that of Comparative Example 1 is that a commercial platinum-carbon catalyst is used as the cathode of the flow cell, and a commercial ruthenium dioxide catalyst is used as the anode of the flow cell in step S4, and the catalyst area is 2 cm 2 , the catholyte of the flow cell is natural seawater, the anolyte is a 1 mol·L -1 solution of potassium hydroxide, and the electrocatalytic reaction is carried out at 25 DEG C, hydrogen is generated by the hydrogen evolution reaction at the cathode, and oxygen is generated by the oxygen evolution reaction at the anode.

[0062] Figure 1 is the flow chart of the method for electrolysis of natural seawater to produce hydrogen by using the low-loading noble metal platinum nickel catalyst provided by the application, and the Pt / Ni(OH)2 obtained in Example 1 is used as the cathode of the flow cell, the NiFe-LDH catalyst is used as the anode of the flow cell, and the catalyst area is 2 cm 2Anion exchange membranes are used to separate the catalysts on both sides; titanium felt is placed between the catalysts and the flow channels of the flow cell as a gas diffusion layer to ensure more uniform gas release and prevent clogging; the cathode electrolyte of the flow cell is natural seawater, and the anolyte is 1 mol·L⁻¹. -1 A potassium hydroxide solution.

[0063] Figure 2 The image shown is a scanning electron microscope (SEM) image of Pt / Ni(OH)2 prepared in Example 1 of this invention. It can be seen that it exhibits a uniform nanoflower morphology. The nanoflowers are assembled from nanosheets with a diameter of about 500 nm, which have more lateral dimensions and abundant metal active sites, which is conducive to the binding of water molecules and improves electrocatalytic performance.

[0064] Figure 3 This is the XPS spectrum of Pt / Ni(OH)2 obtained in Example 1 of this invention. The high-resolution Ni 2p spectrum shows that it belongs to Ni 2p. 3 / 2 and Ni 2p 1 / 2 Ni 2+ The binding energies are 855.3 eV and 873.7 eV, with characteristic peaks belonging to Ni2p. 3 / 2 and Ni 2p 1 / 2 Ni 3+ The binding energies are characterized by peaks of 895.1 eV and 875.3 eV, while the other four peaks correspond to Ni 2p. 3 / 2 and Ni 2p 1 / 2 Satellite peaks; Pt 4f spectrum shows metallic Pt in Example 1. 0 The presence of Pt oxide on the catalyst surface and a small amount of Pt oxide on the catalyst surface δ+ .

[0065] Figure 4 The LSV test results for Example 1 and Comparative Example 1 in the flow cell show that Pt / Ni(OH)2 exhibits better catalytic performance at 60°C, and reaches 1 A·cm⁻¹ at 2.46 V. -1 The current density was approximately 200 mV earlier than at 25°C.

[0066] Figure 5 The LSV test results for Comparative Examples 1-3 of this invention in a flow cell show that, compared with flow cells composed of other commercial catalysts, Pt / Ni(OH)2 as the cathode catalyst and NiFe-LDH as the anode catalyst exhibit significantly better catalytic performance.

[0067] Figure 6 In Example 1 of the present invention, the flow cell was filled with a solution of 0.5 A·cm⁻¹. -1The current density of the continuous electrolysis graph of the Pt / Ni(OH)2 prepared in Example 1 is shown in Figure 2. The results show that it can be continuously electrolyzed in natural seawater for 150 hours without obvious attenuation, which proves the stability and corrosion resistance of the Pt / Ni(OH)2 prepared in Example 1 as a catalyst for electrolyzing natural seawater.

[0068] Figure 7 Figure 3 is a scanning electron microscope photograph of the Pt / Ni(OH)2 prepared in Example 1 after electrolyzing seawater. The results show that there is no obvious change in the morphology, which proves the structural stability of the Pt / Ni(OH)2 prepared in Example 1 as a catalyst for electrolyzing natural seawater.

[0069] Figure 8 Figure 4 is a Raman spectrum of the Pt / Ni(OH)2 prepared in Example 1 before and after electrolyzing seawater. The results show that there is no obvious change in the structure, which also proves the structural stability of the Pt / Ni(OH)2 prepared in Example 1 as a catalyst for electrolyzing natural seawater.

[0070] The above has been described by way of example, but the present application is not limited to the specific embodiments described above, and any modification or change made on the basis of the present application falls within the scope of the present application.

Claims

1. A method for preparing a low-loading noble metal platinum nickel catalyst for hydrogen production from natural seawater, characterized by, The preparation method comprises the following steps: S1, pretreating the foamed nickel substrate; S2, weighing potassium chloroplatinate in a beaker, adding deionized water, stirring to form a uniform solution; S3, transferring the uniform solution obtained in step S2 into the inner liner of the reaction kettle, putting the pretreated foamed nickel obtained in step S1, putting into an oven for hydrothermal reaction, taking out, washing and drying after the end to obtain the low-loading noble metal platinum nickel catalyst; S4, using the low-loading noble metal platinum nickel catalyst obtained in step S3 for electrolysis of natural seawater to produce hydrogen, taking the low-loading noble metal platinum nickel catalyst as the cathode of the flow cell, taking the NiFe-LDH catalyst as the anode of the flow cell, and carrying out electrocatalytic reaction at 60℃, hydrogen is produced by hydrogen evolution reaction at the cathode, and oxygen is produced by oxygen evolution reaction at the anode.

2. The method for preparing a low-loading noble metal platinum nickel catalyst for hydrogen production from natural seawater according to claim 1, characterized in that, The pretreatment of the foamed nickel substrate in step S1 is specifically as follows: first, immerse the foamed nickel substrate in hydrochloric acid and ultrasonic treatment to remove the oxide film on the surface; then, ultrasonic treatment of the foamed nickel substrate in deionized water to remove residual hydrochloric acid, then ultrasonic treatment with ethanol, and then vacuum drying to complete the pretreatment of the foamed nickel substrate.

3. The method for preparing a low noble metal platinum nickel catalyst for hydrogen production from natural seawater according to claim 2, characterized in that, The size of the foam nickel is 30 mm*20 mm*1.6 mm; the concentration of hydrochloric acid is 2-3 mol / L -1 ; the ultrasonic treatment time of hydrochloric acid is 15-20 min, the ultrasonic treatment time of deionized water is 10-15 min, and the ultrasonic treatment time of ethanol is 5-10 min.

4. The method for preparing a low noble metal platinum nickel catalyst for hydrogen production from natural seawater according to claim 1, characterized in that, The mass of potassium chloroplatinate weighed in step S2 is 10 mg, and the volume of deionized water is 20 ml.

5. The method for preparing a low noble metal platinum nickel catalyst for hydrogen production from natural seawater according to claim 1, characterized in that, The temperature of the hydrothermal reaction in step S3 is 100°C, the holding time is 2 h, and the heating rate is 2°C·min -1 .

6. The method for preparing a low noble metal platinum nickel catalyst for hydrogen production from natural seawater according to claim 1, characterized in that, The area of the cathode and anode catalysts described in step S4 was 2 cm 2 .

7. The method for preparing a low noble metal platinum nickel catalyst for hydrogen production from natural seawater according to claim 1, characterized in that, The flow cell cathode electrolyte described in step S4 is natural seawater, and the anode electrolyte is a 1 mol·L -1 -1 solution of potassium hydroxide.

8. A low-loading noble metal platinum nickel catalyst prepared by the preparation method of any one of claims 1-7.

9. The application of the low-loading noble metal platinum nickel catalyst prepared by the preparation method of any one of claims 1-7 in hydrogen production from natural seawater.

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