Method for preparing platinum-based nanowire catalyst and platinum-based nanowire catalyst

Abstract

The invention provides a method for preparing a platinum-based nanowire catalyst and the platinum-based nanowire catalyst. The method for preparing the platinum-based nanowire catalyst comprises the following steps: mixing a water-soluble platinum precursor and an optional non-noble metal precursor or an optional hydrophilic matrix material to obtain a precursor mixture; the precursor mixture is subjected to a reduction reaction in a reactor under the gas phase atmosphere of reducing gas, the platinum-based nanowire catalyst is obtained, and the reduction reaction is carried out at the temperature of 210-270 DEG C.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolysis of water, and in particular to a method for preparing a platinum-based nanowire catalyst and the platinum-based nanowire catalyst. Background Art

[0002] Converting water into hydrogen by electrolysis is a feasible solution for large-scale production of green hydrogen. The hydrogen evolution reaction in water electrolysis involves a multi-electron transfer process. There is a large energy barrier in the reaction process, which leads to a very slow reaction rate and a high overpotential. In the actual reaction process, a suitable hydrogen evolution reaction electrocatalyst is required to accelerate the reaction kinetics. In the actual operation of water electrolysis, the platinum particles of the commonly used commercial Pt / C catalyst are very easy to agglomerate, degrade and fall off, resulting in damage to the catalyst, significant performance degradation and shortened service life. Compared with nanoparticles, one-dimensional platinum-based nanowires have excellent performance in electrocatalysis due to their high flexibility, good conductivity and strong stability, and have attracted much attention. However, the current preparation method of platinum-based nanowires is mainly based on liquid phase preparation, which requires a large amount of organic reagents to participate in the reaction, and the preparation process is complicated and the yield is low. For example, patent application CN111509236A discloses a method for preparing platinum nanowires, wherein a nanowire precursor and a transition metal salt are dissolved in water or an organic solvent to obtain a precursor solution, the precursor solution is subjected to an oxidation reaction to obtain platinum nanowires, and then the transition metal in the platinum nanowires is removed by acid corrosion. This method requires an additional acid etching step and the use of an organic solvent to clean the product, which makes the method more complicated, costly and environmentally harmful. Patent CN109848434B discloses a method for preparing platinum nanowires, in which a nanowire precursor and a surfactant are dissolved in N,N-dimethylformamide, and then thiophene is added to react to obtain nanowires. This method uses a large amount of organic reagents, and also has the problems of high cost and environmental harm. Therefore, designing a large-scale preparation method that can achieve excellent performance and stable structure of platinum-based nanowire catalysts has become a problem that needs to be solved urgently.

[0003] In view of the above problems, it is necessary to develop a method for preparing platinum-based nanowire catalysts with simple process and large-scale production, as well as a platinum-based nanowire catalyst that can achieve high hydrogen evolution rate and high energy conversion efficiency in water electrolysis and high stability of structure and performance. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for preparing a platinum-based nanowire catalyst and a platinum-based nanowire catalyst, so as to solve the problems that the method for preparing a platinum-based nanowire catalyst in the prior art has a complex preparation process and a low yield and that the platinum-based nanowire catalyst in the prior art has poor performance and structural stability.

[0005] In order to achieve the above object, the present invention provides a method for preparing a platinum-based nanowire catalyst, comprising the following steps:

[0006] mixing a water-soluble platinum precursor and an optional non-noble metal precursor or an optional hydrophilic matrix material to obtain a precursor mixture;

[0007] The precursor mixture is subjected to a reduction reaction in a gas phase atmosphere containing a reducing gas to obtain the platinum-based nanowire catalyst, wherein the reduction reaction is carried out at a temperature of 210° C. to 270° C.

[0008] Furthermore, the water-soluble platinum precursor includes potassium chloroplatinite, the non-precious metal precursor includes nickel chloride hexahydrate, the hydrophilic matrix material includes carbon black nanopowder particles, and the reducing gas includes one or more of hydrogen, ammonia, and carbon monoxide.

[0009] Furthermore, the method for preparing a platinum-based nanowire catalyst also includes: dissolving the water-soluble platinum precursor and the optional non-precious metal precursor or the optional hydrophilic matrix material in water to obtain the precursor solution; drying the precursor solution to obtain the precursor mixture for the next step of heat treatment reduction in the gas phase; preferably, the mass ratio of the water-soluble platinum precursor, the non-precious metal precursor, the hydrophilic matrix material and water is 1 to 0.01-1 to 1-10.

[0010] Furthermore, the drying is carried out in a vacuum oven at 40°C to 80°C for 1 to 12 hours.

[0011] Furthermore, the reaction time of the reduction reaction is 30 min to 3 h.

[0012] Furthermore, the gaseous atmosphere includes a mixture of the reducing gas and an inert gas, and the inert gas includes nitrogen or argon.

[0013] Furthermore, the flow rates of the reducing gas and the inert gas are 50 to 300 mL / min.

[0014] Furthermore, before performing the reduction reaction, the method for preparing a platinum-based nanowire catalyst further comprises: grinding the precursor mixture, preferably, the grinding time is 0.5 to 2 hours.

[0015] Furthermore, the reduction reaction is carried out in a tubular reactor placed in a tubular furnace, the two ends of the tubular reactor are respectively connected to an air intake pipeline and an exhaust pipeline, and one end connected to the air intake pipeline has a three-way valve, which is used to switch the type of the reducing gas.

[0016] In order to achieve the above object, another aspect of the present invention also provides a platinum-based nanowire catalyst prepared by the above method.

[0017] By applying the technical solution of the present invention, a method for preparing a platinum-based nanowire catalyst with a simple process is realized, which overcomes the disadvantage of the relatively complicated traditional catalyst preparation process and can achieve large-scale preparation; the use of organic reagents in the traditional wet chemical method for preparing platinum-based nanowires is avoided, the washing process is simple, no special treatment is required, it is green and environmentally friendly, and the catalyst surface cleanliness is high; the method of the present invention is suitable for the preparation of self-supporting platinum-based nanowires, and is also suitable for the preparation of platinum-based nanowires composite-supported by matrix materials, and has wide applicability.

[0018] The nanowires prepared by the present invention can significantly reduce the overpotential of the electrocatalytic hydrogen evolution reaction, achieve a high hydrogen evolution rate and a high energy conversion efficiency in the water electrolysis reaction process, and simultaneously achieve high stability of structure and performance, ensuring long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 A schematic structural diagram of a reactor for preparing a platinum-based nanowire catalyst provided in a preferred embodiment of the present invention.

[0021] Figure 2 This is a transmission electron microscope photograph of the platinum-based nanowire catalyst prepared according to Example 1.

[0022] Figure 3 This is a transmission electron microscope photograph of the platinum-based nanowire catalyst prepared according to Example 2.

[0023] Figure 4 This is a transmission electron microscope photograph of the platinum-based nanowire catalyst prepared according to Example 3.

[0024] Figure 5 HER performance curves of the platinum-based nanowire catalyst prepared according to Example 3 and a commercially available Pt / C catalyst. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0026] As described in the background art, the existing methods for preparing platinum-based nanowire catalysts have the problems of complex preparation process, low yield, and poor performance and structural stability of the prepared platinum-based nanowire catalysts. In order to solve the above technical problems, the present application provides a method for preparing a platinum-based nanowire catalyst, comprising the following steps: mixing a water-soluble platinum precursor and an optional non-precious metal precursor or an optional hydrophilic matrix material to obtain a precursor mixture; subjecting the precursor mixture to a reduction reaction in a gaseous atmosphere containing a reducing gas to obtain a platinum-based nanowire catalyst, wherein the reduction reaction is carried out at a temperature of 210°C to 270°C.

[0027] The present invention achieves the control of the morphology of platinum nanowires of the catalyst by using gas phase reaction conditions and a higher reaction temperature. Compared with the wet method carried out under liquid phase reaction conditions in the prior art, the use of reagents is reduced, the washing process is simple, no special treatment is required, it is green and environmentally friendly, and the catalyst surface cleanliness is high. It can also achieve large-scale preparation and is more conducive to commercial production. The platinum-based nanowires produced by the method of the present invention can be formed only by platinum precursors, can self-support to form a three-dimensional network structure without the aid of other reagents, and have fast electron transmission characteristics. The method of the present invention can also be used to produce self-supporting platinum-based nanowires formed by mixing platinum precursors and non-precious metal precursors, as well as platinum-based nanowires compositely supported by matrix materials with the addition of matrix materials, and have wide applicability.

[0028] In a preferred embodiment, the water-soluble platinum precursor includes potassium chloroplatinite, the non-precious metal precursor includes nickel chloride hexahydrate, the hydrophilic matrix material includes carbon black nanopowder particles, and the reducing gas includes one or more of hydrogen, ammonia, and carbon monoxide.

[0029] The use of the specific precursor, matrix material and reducing gas of the present invention is more conducive to producing platinum-based nanowire catalysts with better performance at higher efficiency.

[0030] In a preferred embodiment, the method for preparing a platinum-based nanowire catalyst further comprises: dissolving a water-soluble platinum precursor and an optional non-precious metal precursor or an optional hydrophilic matrix material in water to obtain a precursor solution; drying the precursor solution to obtain a precursor mixture; preferably, the mass ratio of the water-soluble platinum precursor, the non-precious metal precursor, the hydrophilic matrix material and water is 1 to 0.01-1 to 1-10. If there is too much non-precious metal precursor, the nanowire morphology cannot be formed. If there is too much hydrophilic matrix material, the precious metal loading will be too low and the excellent performance cannot be maintained.

[0031] In the method of the present invention, drying after co-dissolving the precursor is conducive to obtaining a more uniformly mixed precursor mixture. Using the precursor, the matrix material and water in the specific ratio of the present invention is more conducive to producing a platinum-based nanowire catalyst with better performance at a higher efficiency. The co-dissolving and drying steps are conducive to forming a uniform nanowire morphology and are conducive to the full combination of the precursor and the hydrophilic matrix material.

[0032] In a preferred embodiment, the drying is carried out in a vacuum oven at 40°C to 80°C for 1 to 12 hours. The specific drying temperature and time of the present invention are beneficial to improving the drying efficiency and shortening the process cycle. If the temperature is too high or the time is too long, the precursor may be reduced prematurely.

[0033] In a preferred embodiment, the reaction time of the reduction reaction is 30 min to 3 h.

[0034] In a preferred embodiment, the gaseous atmosphere includes a mixture of a reducing gas and an inert gas, and the inert gas includes nitrogen or argon.

[0035] In the method of the present invention, before the reduction reaction is carried out, the air in the reactor can be evacuated by an inert gas, and then a gaseous atmosphere for the reaction is introduced, which may include a mixture of reducing gas and inert gas, which is more conducive to the stable progress of the reaction and avoids the introduction of by-products.

[0036] In a preferred embodiment, the flow rates of the reducing gas and the inert gas are 50-300 mL / min, respectively. If the gas flow rate is too high, the precursor may be purged out of the reaction system without reacting at high temperature.

[0037] In a preferred embodiment, before the reduction reaction, the method for preparing the platinum-based nanowire catalyst further comprises: grinding the precursor mixture, preferably, the grinding time is 0.5 to 2 hours. The grinding step is conducive to obtaining an appropriate precursor particle size.

[0038] In a preferred embodiment, the reduction reaction is carried out in a tubular reactor placed in a tubular furnace, the two ends of the tubular reactor are respectively connected to an air intake pipeline and an exhaust pipeline, and one end connected to the air intake pipeline is provided with a three-way valve.

[0039] The reduction reaction of the present invention can be carried out using a reactor specially designed for the method of the present invention. The reactor of the present invention can be composed of a steel tubular reactor, and it is placed in the middle of a tubular furnace to provide a suitable temperature for the reaction. The two ends of the steel tubular reactor are respectively connected to the air inlet pipeline and the exhaust pipeline, and a three-way valve is provided at the front end for switching the type of reducing gas. The inert gas introduced can be nitrogen and / or argon, and the reducing gas or a mixture of reducing gas and inert gas is introduced after the air in the reactor is exhausted.

[0040] In a preferred embodiment, the method for preparing a platinum-based nanowire catalyst further comprises: washing the platinum-based nanowire catalyst product obtained by the reduction reaction, and dispersing it in ethanol for storage.

[0041] Another aspect of the present application provides a platinum-based nanowire catalyst, which is prepared by the above-mentioned method for preparing a platinum-based nanowire catalyst. Compared with nanoparticles, it has high flexibility, good conductivity and strong stability, and exhibits excellent performance in electrocatalysis, which has attracted much attention. However, the current preparation method for platinum-based nanowires is mainly liquid phase preparation, which requires a large amount of organic reagents to participate in the reaction, and the preparation process is complicated and the yield is low. Therefore, the present application designs a macro-scale preparation method that can achieve excellent performance and stable structure of platinum-based nanowire catalysts.

[0042] The nanowires prepared by the present invention can significantly reduce the overpotential of the electrocatalytic hydrogen evolution reaction, achieve a high hydrogen evolution rate and a high energy conversion efficiency in the water electrolysis reaction process, and simultaneously achieve high stability of structure and performance, ensuring long service life.

[0043] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0044] The platinum-based nanowire catalysts were prepared by the following examples.

[0045] Example 1

[0046] (1) Dissolve 41.51 mg of potassium chloroplatinite in 5 mL of deionized water, ultrasonicate for 10 min, place in a vacuum oven, evaporate the water at 60 °C for 4 h, and then scrape off the solid powder.

[0047] (2) The solid powder is spread evenly in a quartz boat so that the powder can fully contact with the gas introduced into the reactor.

[0048] (3) Introduce argon into the reactor. After 15 minutes, when the air in the reactor is exhausted, introduce a 5% hydrogen (reducing gas) and argon (inert gas) mixture at a flow rate of hydrogen / argon (100 / 190) mL / min. At the same time, increase the temperature from room temperature to above 230°C at a rate of 5°C / min, keep the temperature for 2 hours, and then cool it down to room temperature naturally.

[0049] (4) After the reaction is completed, argon gas is introduced to exhaust the residual hydrogen in the reactor. The reduced solid powder is taken out, dispersed with deionized water, and then centrifuged after ultrasonication. After this washing process is repeated twice, the sample is dispersed in anhydrous ethanol again and stored for later use.

[0050] Example 2

[0051] The difference from Example 1 is that in step (1), 41.51 mg of potassium chloroplatinite and 23.77 mg of nickel chloride hexahydrate are co-dissolved in 5 mL of deionized water.

[0052] Example 3

[0053] The difference from Example 2 is that in step (1), 41.51 mg of potassium chloroplatinite is dissolved in 5 mL of deionized water, and then 50 mg of carbon black nanopowder particles are added.

[0054] Example 4

[0055] The difference from Example 1 is that the reaction in step (3) is carried out at 260°C.

[0056] Example 5

[0057] The difference from Example 1 is that the reaction in step (3) is carried out for 0.5 h.

[0058] Example 6

[0059] The difference from Example 2 is that the heating rate in step (3) is 10°C / min.

[0060] Example 7

[0061] The difference from Example 3 is that the flow rate in step (3) is hydrogen / argon (50 / 100) mL / min.

[0062] Example 8

[0063] The difference from Example 1 is that the drying temperature in step (1) is 70°C.

[0064] Example 9

[0065] The difference from Example 1 is that the drying time in step (1) is 8 hours.

[0066] Example 10

[0067] The difference from Example 1 is that the reducing gas and the inert gas are carbon monoxide and nitrogen respectively.

[0068] Embodiment 11

[0069] The difference from Example 1 is that the dissolution and drying steps are not performed and the reduction reaction is directly performed after the precursor is ground.

[0070] Comparative Example 1

[0071] The commercially available platinum-carbon catalyst is model HiCaP40.

[0072] Comparative Example 2

[0073] The difference from Example 1 is that the temperature of the reduction reaction is 350°C.

[0074] Comparative Example 3

[0075] The difference from Example 2 is that the amount of nickel chloride hexahydrate used in step (1) is 98.57 mg.

[0076] Comparative Example 4

[0077] The difference from Example 3 is that the amount of carbon black nanopowder particles used in step (1) is 500 mg.

[0078] Comparative Example 5

[0079] The difference from Example 1 is that the drying temperature is 100° C. and the drying time is 24 h.

[0080] Comparative Example 6

[0081] The difference from Example 1 is that the reduction reaction time is 5 h.

[0082] Comparative Example 7

[0083] The difference from Example 1 is that the flow rates of hydrogen and argon are both 400 mL / min.

[0084] Figure 2-4 The transmission electron microscope photo of the platinum-based nanowire catalyst prepared in Example 1-3. Figure 2-4 It can be seen that the platinum-based nanowires produced by the method of the present invention can be formed only from a platinum precursor, can be self-supported to form a three-dimensional network structure without the aid of other reagents, and have fast electron transmission characteristics. The method of the present invention can also be used to produce self-supporting platinum-based nanowires formed by mixing a platinum precursor and a non-precious metal precursor, as well as platinum-based nanowires added with a matrix material and compositely supported by a matrix material.

[0085] The HER performance of the platinum-based nanowire catalysts prepared in the above-mentioned embodiments was tested on an electrochemical workstation (CHI 760E). A typical three-electrode system was used, with a glassy carbon rotating disk electrode (RDE, 5 mm in diameter, 0.196 cm2 in area) as the working electrode, a platinum wire (1 cm2) as the counter electrode, and an Ag / AgCl as the reference electrode. The overpotential of the LSV at a current density of 10 mA / cm2 was measured for the embodiments, as shown in Table 1.

[0086] Table 1

[0087] <![CDATA[Overpotential @ 10 mA cm -2 (mV)]]> Example 1 25 Example 2 23 Example 3 16 Example 4 24 Example 5 28 Example 6 24 Example 7 30 Example 8 28 Example 9 27 Example 10 28 Embodiment 11 36 Comparative Example 1 29 Comparative Example 2 35 Comparative Example 3 36 Comparative Example 4 39 Comparative Example 5 31 Comparative Example 6 37 Comparative Example 7 34

[0088] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: Figure 5 By comparing Examples 1-11 and Comparative Examples 2-7 with Comparative Example 1, it can be seen that the platinum-based nanowire catalyst prepared by the method of the present invention has similar or even better catalytic performance than the commercially available platinum-carbon catalyst. In addition, compared with the wet method under liquid phase reaction conditions in the prior art, the method of the present invention reduces the use of reagents, has a simple washing process, does not require special treatment, is green and environmentally friendly, and has a high degree of cleanliness on the catalyst surface, and can achieve large-scale preparation, which is more conducive to commercial production.

[0089] It can be seen from Examples 1-3 that the platinum-based nanowires produced by the method of the present invention can be formed only by a platinum precursor, and can self-support to form a three-dimensional network structure without the aid of other reagents. The method of the present invention can also be used to produce self-supporting platinum-based nanowires formed by a mixture of a platinum precursor and a non-precious metal precursor, as well as platinum-based nanowires added with a matrix material and compositely supported by a matrix material.

[0090] By comparing Examples 1, 4, 5 and Comparative Examples 2, 6, it can be seen that the reduction reaction carried out within the specific temperature and time range of the present invention can obtain a platinum-based nanowire catalyst with further improved catalytic performance.

[0091] By comparing Examples 1-10 and Example 11, it can be seen that the method of the present invention further includes the steps of dissolving to obtain a precursor solution and drying the precursor solution to obtain a platinum-based nanowire catalyst with further improved catalytic performance.

[0092] Comparison of Examples 1-3 and Comparative Examples 3-4 shows that the use of the mass ratio of the water-soluble platinum precursor, the non-precious metal precursor, the hydrophilic matrix material and water within the specific range of the present invention can obtain a platinum-based nanowire catalyst with further improved catalytic performance.

[0093] By comparing Examples 1, 8, 9 and Comparative Example 5, it can be seen that the above drying within the specific temperature and time range of the present invention can obtain a platinum-based nanowire catalyst with further improved catalytic performance.

[0094] Comparison of Examples 1 and 7 with Comparative Example 7 shows that the use of the reducing gas and the inert gas flow rates within the specific ranges of the present invention can obtain a platinum-based nanowire catalyst with further improved catalytic performance.

[0095] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a platinum-based nanowire catalyst, characterized in that: The method for preparing a platinum-based nanowire catalyst comprises the following steps: mixing a water-soluble platinum precursor and an optional non-noble metal precursor or an optional hydrophilic matrix material to obtain a precursor mixture; The precursor mixture is subjected to a reduction reaction in a gas phase atmosphere containing a reducing gas to obtain the platinum-based nanowire catalyst, wherein the reduction reaction is carried out at a temperature of 210° C. to 270° C.

2. The method for preparing a platinum-based nanowire catalyst according to claim 1, characterized in that: The water-soluble platinum precursor includes potassium chloroplatinite, the non-precious metal precursor includes nickel chloride hexahydrate, the hydrophilic matrix material includes carbon black nanopowder particles, and the reducing gas includes one or more of hydrogen, ammonia, and carbon monoxide.

3. The method for preparing a platinum-based nanowire catalyst according to claim 1 or 2, characterized in that: The method for preparing a platinum-based nanowire catalyst further comprises: Dissolving the water-soluble platinum precursor and the optional non-noble metal precursor or the optional hydrophilic matrix material in water to obtain the precursor solution; Drying the precursor solution to obtain the precursor mixture for the next step of heat treatment reduction in the gas phase; Preferably, the mass ratio of the water-soluble platinum precursor, the non-precious metal precursor, the hydrophilic matrix material and water is 1-0.01-1 to 1-10.

4. The method for preparing a platinum-based nanowire catalyst according to claim 3, characterized in that: The drying is carried out in a vacuum oven at 40° C. to 80° C. for 1 to 12 hours.

5. The method for preparing a platinum-based nanowire catalyst according to claim 1 or 2, characterized in that: The reaction time of the reduction reaction is 30 min to 3 h.

6. The method for preparing a platinum-based nanowire catalyst according to claim 1 or 2, characterized in that: The gas phase atmosphere includes a mixture of the reducing gas and an inert gas, and the inert gas includes nitrogen or argon.

7. The method for preparing a platinum-based nanowire catalyst according to claim 6, characterized in that: The flow rates of the reducing gas and the inert gas are 50 to 300 mL / min.

8. The method for preparing a platinum-based nanowire catalyst according to claim 1, characterized in that: Before performing the reduction reaction, the method for preparing a platinum-based nanowire catalyst further comprises: grinding the precursor mixture, preferably, the grinding time is 0.5 to 2 hours.

9. The method for preparing a platinum-based nanowire catalyst according to claim 1, characterized in that: The reduction reaction is carried out in a tubular reactor placed in a tubular furnace. The two ends of the tubular reactor are respectively connected to an air intake pipeline and an exhaust pipeline, and one end connected to the air intake pipeline is provided with a three-way valve, which is used to switch the type of the reducing gas.

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