Nano-porous nickel phosphide-platinum composite catalyst for hydrogen production by electrolysis of water, preparation method and application of nano-porous nickel phosphide-platinum composite catalyst

Abstract

The invention belongs to the technical field of hydrogen production catalysis, and particularly relates to a nano-porous nickel phosphide-platinum composite catalyst for hydrogen production through water electrolysis, a preparation method and application. The preparation method comprises the following steps: firstly, carrying out electro-deposition to prepare a nano-porous NixP catalyst under the action of a hydrogen bubble dynamic template by using a three-electrode system under the conditions of room temperature and stirring and adopting a constant-current or constant-potential method; and soaking the prepared nano-porous NixP catalyst in an H2PtCl6 solution, washing and naturally drying to obtain a trace Pt-loaded nano-porous Pt-coated NixP catalyst, namely the nano-porous nickel phosphide-platinum composite catalyst for hydrogen production by electrolyzing water. The problems that a preparation method of a noble metal cathode electrolysis water hydrogen evolution catalyst is complex, high in price and scarce in resource are solved, a trace amount of platinum is loaded on the surface of NixP with high catalytic hydrogen evolution activity and high specific surface through a simple electrochemical deposition and dynamic template technology in combination with a chemical replacement reaction method, and the catalyst is prepared. The catalytic hydrogen evolution activity and stability of NixP are remarkably improved, the preparation method of the catalyst is simple, and the catalyst has remarkable practical value.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen evolution catalysis, and relates to a composite catalyst for producing hydrogen by electrochemical cathode electrolysis of water, and specifically relates to a nickel phosphide-platinum composite catalyst for producing hydrogen by electrolysis of water, a preparation method and an application thereof. Background Art

[0002] With the growth of global energy demand and the reduction of dependence on traditional fossil fuels, exploring efficient and environmentally friendly new energy technologies has become an important issue in the 21st century. Hydrogen is regarded as an ideal clean energy carrier because its only energy release product is water and it does not emit greenhouse gases. However, most hydrogen is currently extracted from natural gas, which is not in line with the concept of sustainable development. Water electrolysis is a green way to produce hydrogen and has attracted much attention, but it is inefficient and requires efficient electrocatalysts to reduce overpotential. Although traditional platinum group precious metal catalysts have high catalytic activity, their resources are scarce and they are expensive. Therefore, the development of low-cost, high-efficiency non-precious metal catalysts is the key to improving the economic efficiency of hydrogen production by water electrolysis.

[0003] Nickel phosphide (Ni x As an emerging non-precious metal electrocatalyst, nickel phosphide is favored by researchers due to its excellent performance. Nickel phosphide can be synthesized by a variety of methods, including but not limited to physical vapor deposition, chemical vapor deposition, solid-state reaction, sol-gel method, wet chemical method, etc. Electrochemical deposition is a type of wet chemical method. Compared with other methods, it has the advantages of simple method, low energy consumption, simple equipment, environmental friendliness, low cost, high atomic utilization rate, and easy scale-up. It is a competitive method in the preparation of nickel phosphide as a catalyst for hydrogen evolution by electrolysis of water, and is particularly suitable for the preparation of materials with complex structures or high surface areas.

[0004] However, the catalytic activity of nickel phosphide is still lower than that of precious metal platinum group catalysts, and the specific surface area needs to be improved. At the same time, the stability of non-precious metal nickel phosphide is also lower than that of precious metal platinum group catalysts. Therefore, combining the advantages of both, compounding precious metals with non-precious metal nickel phosphides is an effective method for preparing cathode hydrogen evolution catalysts with good catalytic activity, high stability, low cost, and high specific surface area, which has significant practical application value. Summary of the invention

[0005] In view of this, the present invention provides a nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst, a preparation method and application thereof, in order to solve the problems that most of the existing hydrogen evolution catalysts are mainly composed of precious metals such as platinum and palladium, the raw material cost is high, and the preparation methods of reported non-precious metal catalysts are complex, the conditions are harsh, the catalytic activity is low and the stability is poor.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The first technical purpose of the present invention is to provide a method for preparing a nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst, the method specifically comprising the following steps:

[0008] (1) First prepare nanoporous Ni x P catalyst, using a three-electrode system, with a carbon disc electrode as the working electrode, a carbon rod as the counter electrode, and Ag / AgCl (3M KCl) as the reference electrode, the three electrodes are placed in a mixed solution, and at room temperature, under the conditions of stirring with a magnetic stirrer, a constant current or constant potential method is used, and hydrogen bubbles are used as a dynamic template for electrodeposition. After the deposition is completed, it is carefully rinsed with deionized water, and after drying, nanoporous Ni is obtained on the carbon disc electrode. x P catalyst;

[0009] (2) The nanoporous Ni prepared in step (1) x P catalyst is placed in H 2 PtCl 6 The nanoporous Pt@Ni substrate was immersed in the solution, then rinsed with deionized water and dried naturally to obtain a trace amount of Pt loaded nanoporous Pt@Ni x The P catalyst is the nanoporous nickel phosphide-platinum composite catalyst for hydrogen production by electrolysis of water.

[0010] Furthermore, the composition of the mixed solution is as follows:

[0011] 0.1M NiSO 4 , 0.1M NH 4 Cl, 0.3M NaH 2 PO 2 , 0.15MH 3 BO 3 .

[0012] Furthermore, the constant current electrodeposition parameters are as follows:

[0013] Current density: -1~-100mA cm -2 , the deposition time is 5 to 60 minutes.

[0014] Further, the constant potential electrodeposition parameters are as follows;

[0015] The potential is -0.8 to -1.2 V, and the deposition time is 5 to 60 minutes.

[0016] Furthermore, the H 2 PtCl 6 The concentration of the solution is 0.01 to 10 mM, and the soaking time is 1 to 80 minutes.

[0017] The second object of the present invention is to provide a nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst prepared by the above method, wherein the composite catalyst is Pt@Ni x P catalyst, Pt loading is 0.001~0.1%.

[0018] It should be noted that different concentrations of chloroplatinic acid and different replacement times will result in different mass fractions of Pt. The preferred condition in this case is 0.1 mM H 2 PtCl 6 Solution, soak and displace for 10 minutes, 0.03% Pt content.

[0019] The third object of the present invention is to provide a nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst prepared by the method as described above and used in water electrolysis hydrogen evolution.

[0020] Specifically, the nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst is used in electrochemical cathode hydrogen evolution.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The invention solves the problems of complex preparation method, high price and scarce resources of noble metal cathode water electrolysis hydrogen evolution catalyst. A trace amount of platinum is loaded on the surface of nanoporous nickel phosphide with good catalytic hydrogen evolution activity and high specific surface area through a simple electrochemical deposition technology combined with a chemical replacement reaction method, so that the catalytic hydrogen evolution activity and stability of the nickel phosphide are significantly improved, and the weight percentage of platinum is only 0.03%. The catalyst of the invention has simple preparation method, low cost, high catalytic activity and good stability, and the catalytic hydrogen evolution current can be increased by 10 times at most, and has significant practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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 or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 It's Ni x SEM images of P (left), Pt@Ni x SEM image of P (right).

[0025] Figure 2 It's Pt@Ni x P and Ni x Linear sweep voltammogram of P, the electrolyte is 0.5 M KOH.

[0026] Figure 3 Pt@Ni at different overpotentials x P and Ni x The ratio of the current of hydrogen evolution in water electrolysis at the catalytic cathode of P.

[0027] Figure 4 It's Pt@Ni x P and Ni x Comparison of Nernquist spectra of P.

[0028] Figure 5 It's Pt@Ni x P and Ni x Comparison of Tafel slopes of P.

[0029] Figure 6 It's Pt@Ni x P catalyst at 10mA / cm 2 Stability evaluation under current of .

[0030] Figure 7 It's Pt@Ni x Pore ​​size distribution of catalyst P. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0033] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0034] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0035] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0036] The invention discloses a preparation method of a nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst and application of the catalyst in electrochemical cathode water electrolysis hydrogen production.

[0037] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0038] Example 1

[0039] A preparation method and application of a nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst, the specific operation is as follows:

[0040] (1) Prepare Ni first x P catalyst, using a three-electrode system (carbon disc electrode as working electrode, carbon rod as counter electrode, Ag / AgCl (3M KCl) as reference electrode), the three electrodes were placed in a mixed solution (0.1M NiSO 4 , 0.1MNH 4 Cl, 0.3MNaH 2 PO 2 , 0.15MH 3 BO 3 ) at room temperature with a magnetic stirrer and a constant current (optimum: current density of -10 mA cm -2 Electrodeposition was performed by the constant potential method (optimum: potential of -1.05 V, deposition time of 20 minutes), and after the deposition was completed, the nanoporous Ni was carefully rinsed with deionized water and dried to obtain the nanoporous Ni on the carbon disc electrode. x P catalyst.

[0041] (2) The nanoporous Ni prepared above x P catalyst was placed in 0.1 mM H 2 PtCl 6 The solution was immersed in water for 10 minutes, then rinsed with deionized water and dried naturally to obtain Pt@Ni x P catalyst.

[0042] (3) The cathode electrolysis and hydrogen evolution performance of the catalyst was tested in 1 M KOH solution.

[0043] It should be further noted that the constant current (current density of -5, -10, -15 mA cm -2 Nanoporous Ni can be prepared by electrodeposition using either a constant potential (potential of -0.8 to -1.2 V, deposition time of 10 to 40 minutes) or a constant potential (potential of -0.8 to -1.2 V, deposition time of 10 to 40 minutes). x P, to obtain the optimal conditions.

[0044] The formation of nanopores is due to the fact that nickel phosphide is a hydrogen evolution catalyst. Hydrogen bubbles are generated simultaneously during the electrodeposition of nickel phosphide. The hydrogen bubbles act as a dynamic template to create a large number of nanopores in nickel phosphide. The BET test results show that the specific surface area is 13m 2 / g, the pore size measured by BJH method is less than 20nm, see Figure 7 .

[0045] The Ni prepared above x P catalyst was placed in 0.1 mM H 2 PtCl 6 The solution was immersed for 1, 5, 10, 40, and 80 minutes, then rinsed with deionized water and dried naturally to obtain Pt@Ni x P catalyst.

[0046] Weigh the carbon sheet and Ni separately using an electronic balance with an accuracy of one hundred thousandth. x P / carbon sheet, obtain Ni x The deposition quality of P. The Pt@Ni x The percentage of Pt in the P catalyst can be used to obtain the mass (load) of Pt in the catalyst. x In the P catalyst, the weight percentage of Ni is 91.01% and the weight percentage of P is 8.99%. After Pt loading, the weight percentage of Ni in the catalyst decreases (90.60%), while the weight percentage of P increases (9.37%). The results show that Ni x The main component of P catalyst is Ni 0 , Ni 0 With H 2 PtCl 6 After the reaction, Ni 0 The percentage of P in Pt@Ni x The content of P on the surface of the catalyst is extremely low, only 0.03% by weight, and the loading capacity is about 145.9 μg g -1 .

[0047] Finally, the electrochemical hydrogen evolution performance of the prepared catalyst was evaluated by electrochemical methods.

[0048] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the following experimental examples are used to further illustrate the technical features disclosed in the present invention, but they should not be understood as limiting the present invention. Other improvements made by those skilled in the art based on the above invention content without creative work are also considered to fall within the scope of protection of the present invention.

[0049] Experimental example:

[0050] It should be noted that the Pt@Ni x The P catalysts were all prepared by the method shown in the above Example 1.

[0051] like Figure 1 As shown, Ni x The surface of P is slightly granular under SEM observation, but its in-situ nanoporous structure can be obtained from the determination of electrochemical active surface area. This information is due to the hydrogen bubbles generated during electrodeposition acting as dynamic templates; Pt@Ni x The surface of P is fish scale-like, which is different from Ni x P, indicating that Pt was successfully loaded on Ni x P. The chemical reaction equation is: 2Ni+H 2 PtCl 6 =2NiCl 2 +Pt+2HCl, the formation of Ni is because nickel phosphide is similar to the alloy structure, some Ni atoms do not form molecular compounds with P atoms, and are in atomic state, which can undergo chemical replacement reaction with chloroplatinic acid, thereby precipitating platinum atoms to Ni x P surface, while the substitution reaction makes Ni x The ratio of Ni to P in P is optimized, which enhances the catalytic activity of the composite catalyst.

[0052] The performance of the two catalysts was compared using linear sweep voltammetry. Figure 2 It can be seen that at the same overpotential, Pt@Ni x The hydrogen evolution current of water electrolysis at the cathode of P is significantly higher than that of Ni x P, at the same current density, Pt@Ni x The overpotential of hydrogen evolution in water electrolysis at P cathode is significantly lower than that of Ni x P. The results show that: Pt@Ni x The catalytic performance of P is significantly higher than that of Ni x P.

[0053] The hydrogen evolution currents of the two catalysts were compared at different overpotentials. Figure 3 It can be seen that at -0.1V, Pt@Ni x The current of hydrogen evolution from water electrolysis at the cathode of P is Ni xP, the enhancement factor decreases with the increase of overpotential, but is still significantly higher than Ni x The cathode electrolysis current of hydrogen evolution.

[0054] Through electrochemical impedance spectroscopy testing, the Nyquist spectrum is obtained, such as Figure 4 The diameter of the semicircle shows the magnitude of the charge transfer resistance in the catalytic reaction. Obviously, Pt@Ni x The charge transfer internal resistance of P catalyst is lower than that of Ni x P, which is more conducive to rapid hydrogen evolution.

[0055] like Figure 5 The Tafel curve (logarithmic relationship between overpotential and current density) test results show that with the same degree of current density increase, Pt@Ni x The overpotential of P increase is significantly lower than that of Ni x P, Pt@Ni prepared by the method of the present invention x The P-catalyzed cathode has higher hydrogen production activity and faster hydrogen production rate.

[0056] like Figure 6 , by constant current (10 mA cm -2 ) Test of hydrogen evolution by cathode electrolysis of water. Within 10 hours, the catalyst has good stability and no obvious increase in overpotential. Among them, the step-shaped is the current disturbance caused by the bubble removal operation.

[0057] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a nanoporous nickel phosphide-platinum composite catalyst for hydrogen production by water electrolysis, characterized in that: The method specifically comprises the following steps: (1) Using a three-electrode system, with a carbon disc electrode as the working electrode, a carbon rod as the counter electrode, and Ag / AgCl as the reference electrode, the three electrodes are placed in a mixed solution, and the electrodeposition is performed at room temperature and under stirring conditions using a constant current or constant potential method with hydrogen bubbles as a dynamic template. After the deposition is completed, the electrode is carefully rinsed with deionized water and dried to obtain nanoporous Ni on the carbon disc electrode. x P catalyst; (2) The nanoporous Ni prepared in step (1) x The P catalyst was immersed in H2PtCl6 solution, then rinsed with deionized water and dried naturally to obtain a nanoporous Pt@Ni with trace amounts of Pt. x The P catalyst is the nanoporous nickel phosphide-platinum composite catalyst for hydrogen production by electrolysis of water.

2. The method for preparing the nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst according to claim 1, characterized in that: The composition of the mixed solution is as follows: 0.1MNiSO4, 0.1MNH4Cl, 0.3MNaH2PO2, 0.15M H3BO3.

3. The method for preparing the nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst according to claim 1, characterized in that: The constant current electrodeposition parameters are as follows: Current density: -1~-100mA cm -2 , the deposition time is 5 to 60 minutes.

4. The method for preparing the nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst according to claim 1, characterized in that: The constant potential electrodeposition parameters are as follows: The potential is -0.8 to -1.2 V, and the deposition time is 5 to 60 minutes.

5. The method for preparing the nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst according to claim 1, characterized in that: The concentration of the H2PtCl6 solution is 0.01 to 10 mM, and the soaking time is 1 to 80 minutes.

6. A nanoporous nickel phosphide-platinum composite catalyst for hydrogen production by electrolysis of water prepared by the method according to claim 1, characterized in that: The composite catalyst is a nanoporous Pt@Ni x P catalyst, Pt loading is 0.001~0.1%.

7. Use of the nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst prepared by the method according to claim 1 or the nanoporous nickel phosphide-platinum water electrolysis hydrogen production composite catalyst according to claim 6 in water electrolysis hydrogen evolution.

8. The use according to claim 7, characterized in that: The nickel phosphide-platinum water electrolysis hydrogen production composite catalyst is used in electrochemical cathode hydrogen evolution.

Images