A single atom and nanoparticle composite system catalyst with low platinum content and its preparation and application

Abstract

The present invention relates to a single atom and nanoparticle composite system catalyst with low platinum content and its preparation and application. The preparation process of the catalyst is specifically as follows: (1) plasma treatment of graphene oxide powder to obtain nitrogen-doped reduced graphene oxide; (2) uniformly dispersing nitrogen-doped reduced graphene oxide and a certain amount of chloroplatinic acid in a solvent, freeze-drying the dispersion to obtain a precursor powder, or coating the dispersion on a load electrode or a carbon paper surface, and naturally drying to obtain a precursor electrode; (3) placing the precursor powder or the precursor electrode in a vacuum chamber, plasma treatment, and obtaining a target product. The present invention obtains catalysts with different morphologies by changing the amount of chloroplatinic acid added in the precursor and the plasma treatment process, and is suitable for the application of catalytic hydrogen evolution reaction under industrial-grade current density.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts and relates to a single atom and nanoparticle composite system catalyst with low platinum content and the preparation and application thereof. Background Art

[0002] With the consumption of fossil fuels and the intensification of the greenhouse effect, the development of green and clean new energy is an important way to solve the energy crisis and environmental problems. Hydrogen energy, as a green energy with abundant reserves, high calorific value, high energy density and diverse sources, has become an important strategic energy to solve the energy crisis and environmental problems.

[0003] The main technologies for hydrogen production include thermochemical hydrogen production and water electrolysis. Thermochemical hydrogen production technology mainly comes from fossil energy and chemical raw materials, which has the disadvantages of low conversion efficiency, poor economy, pollution and carbon emissions. Water electrolysis can use new energy such as photovoltaic and wind power to electrolyze water to produce hydrogen. This method of hydrogen production has near-zero carbon emissions and is an important technology for achieving "green hydrogen" production.

[0004] The process of producing hydrogen by electrolysis of water requires a catalyst to reduce the overpotential. For the hydrogen evolution reaction occurring at the cathode, the current commercial catalyst is still mainly based on the precious metal platinum. Commercial platinum carbon uses conductive carbon black as the substrate and loads larger platinum particles. The utilization rate of precious metals is low, and the mass content of platinum in the catalyst is as high as 20wt%. The high price of precious metals is a major reason for the high cost of producing hydrogen by electrolysis of water. Reducing the amount of platinum in the catalyst while maintaining good catalytic performance can greatly reduce costs, but there is currently no report on the application of catalysts with low platinum content in catalyzing hydrogen evolution reactions at industrial-grade current density. Summary of the invention

[0005] The purpose of the present invention is to provide a single atom and nanoparticle composite system catalyst with low platinum content and its preparation and application, which has high catalytic activity and stability under industrial current density. In addition, the present invention can also realize the preparation of catalysts with different morphologies by controlling the addition amount of chloroplatinic acid in the precursor and the plasma treatment process to obtain a hydrogen evolution reaction catalyst with the best performance.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One of the technical solutions of the present invention provides a method for preparing a single atom and nanoparticle composite system catalyst with low platinum content, comprising the following steps:

[0008] (1) subjecting graphene oxide powder to a first plasma treatment to obtain nitrogen-doped reduced graphene oxide;

[0009] (2) uniformly dispersing nitrogen-doped reduced graphene oxide and chloroplatinic acid in a solvent to obtain a dispersion, freeze-drying the dispersion to obtain a precursor powder, or coating the dispersion on a load electrode or a carbon paper surface and drying naturally to obtain a precursor electrode;

[0010] (3) Placing the precursor powder or the precursor electrode in a vacuum chamber and performing a second plasma treatment to obtain a target product catalyst, or a target product catalyst covered on the surface of a load electrode or carbon paper.

[0011] Furthermore, during the first plasma treatment in step (1), the plasma used is a non-thermal equilibrium plasma, the discharge atmosphere is a mixed gas of argon and ammonia, and the background vacuum is 1-5Pa.

[0012] Furthermore, during the first plasma treatment, the flow ratio of argon gas to ammonia gas is 95:5 to 80:20.

[0013] Furthermore, during the first plasma treatment in step (1), the discharge power is 50 to 500 W and the treatment time is 1 to 30 min.

[0014] Furthermore, in step (2), the solvent is a mixed solvent of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water is (0-1):1, and the amount of ethanol added is not 0.

[0015] Furthermore, in step (2), the addition amount of chloroplatinic acid and nitrogen-doped reduced graphene oxide satisfies: the mass content of platinum relative to the nitrogen-doped reduced graphene oxide is 0.5wt% to 5wt%, and the PtCl6 in the dispersion is 2- The molar concentration is 0.01~0.5mmol / L.

[0016] Furthermore, during the second plasma treatment in step (3), the plasma used is a non-thermal equilibrium plasma, the discharge atmosphere is argon, and the background vacuum is 1-5Pa.

[0017] Furthermore, during the second plasma treatment in step (3), the discharge power is 50 to 500 W, and the plasma treatment time is 0.5 to 10 min.

[0018] The second technical solution of the present invention provides a single atom and nanoparticle composite system catalyst with low platinum content, which is prepared by any of the preparation methods described above.

[0019] The third technical solution of the present invention provides an application of a single atom and nanoparticle composite system catalyst with low platinum content, which is used to catalyze the hydrogen evolution reaction under industrial-grade current density. Specifically, when it is used to catalyze the hydrogen evolution reaction, at 10 mA cm-2 The overpotential at the current density is 18 mV, and at 1000 mA cm -2 The overpotential under the current density is 130 mV, and the performance is better than the commercial platinum carbon catalyst with a platinum mass content of 20 wt%. The platinum loading in the catalyst prepared by the present invention is less than 5 wt%.

[0020] The present invention first treats graphene oxide powder with non-thermal equilibrium plasma, and the discharge atmosphere is a mixed gas of argon and ammonia, and the purpose is to reduce and nitrogen-dope graphene oxide at the same time, and obtain nitrogen-doped reduced graphene oxide, and nitrogen-doping can be used as the anchoring point of platinum single atoms, and a bonding structure with single-atom platinum is formed in subsequent steps. The high-density electrons and free radicals contained in the plasma discharge atmosphere can reduce the oxygen-containing groups on the surface of graphene oxide, improve its conductivity, and at the same time, the amine ions dissociated from ammonia have a very high reactivity, and the nitrogen-doping of the graphene plane can be realized, and the introduction of ammonia further improves the reduction effect. Graphene has a very large specific surface area, extremely high conductivity and stability, and is an excellent catalyst carrier. In the present invention, nitrogen-doped reduced graphene oxide is used as a substrate for loading platinum, and the reduction of plasma treatment is not completely sufficient, and a certain amount of oxygen-containing groups are still present on the graphene surface, which can be used as a site for adsorbing platinum ions. In the present invention, different amounts of chloroplatinic acid are added when preparing the precursor solution, and the purpose is to explore the optimal balance between platinum loading and catalyst performance, so as to reduce costs. The second step of plasma treatment in the present invention uses argon plasma to reduce the catalyst precursor, and the high-density electrons dissociated from the argon plasma can realize the rapid reduction of platinum ions to form platinum nanoparticles and platinum single atoms. In the present invention, when the amount of chloroplatinic acid added in the catalyst precursor is low, a single-atom platinum catalyst is formed, and the amount of chloroplatinic acid added is further increased to form a system catalyst of a composite of platinum single atoms and nanoparticles. Density functional theory calculations show that under low current density conditions, platinum single atoms have better catalytic activity than platinum nanoparticles, but under high current density conditions, the performance of platinum single atoms is significantly attenuated, and platinum nanoparticles still have excellent catalytic activity, so the composite system of platinum single atoms and nanoparticles can take into account the performance under low current and high current density conditions, and is more stable in high current tests. The platinum content is determined by inductively coupled plasma mass spectrometry, and the mass content of platinum in the final catalyst is much lower than 20wt% of commercial platinum carbon catalysts. The embodiment of the present invention uses microwave plasma, and other types of non-thermal equilibrium plasmas can also be used, but the power, gas pressure and processing time of the plasma need to be adjusted accordingly.

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

[0022] 1. The present invention relates to a single atom and nanoparticle composite system catalyst with a low platinum content, which can be applied to industrial-grade current density catalytic hydrogen evolution reaction. The non-thermal equilibrium plasma technology used is a clean and pollution-free material preparation and modification technology, and the target catalyst can be synthesized in a short time.

[0023] Second, the present invention prepares a single atom and nanoparticle composite catalyst with a platinum loading of less than 5wt% by adjusting the amount of chloroplatinic acid added to the precursor and the plasma treatment time, thereby reducing the cost of hydrogen production by electrolysis of water from the source by reducing the amount of precious metals. The catalyst uses graphene as a substrate, and the size of the platinum nanoparticles on the surface is less than 2nm, which greatly increases the active specific surface area of ​​the catalyst. The catalyst reaches 1000mA cm -2 The current density only requires 130 mV overpotential and can reach 1400 mA cm -2 It can work stably for more than 24 hours at a current density of 1.547 W.

[0024] 3. The technical route provided by the present invention can be applied to the preparation of other metal single atom and nanoparticle composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Transmission electron microscopy (TEM) morphology of nitrogen-doped reduced graphene oxide.

[0026] Figure 2 This is the TEM morphology of Pt / p-GO@50-2min prepared in Example 2.

[0027] Figure 3 This is the spherical aberration corrected transmission electron microscopy (AC-TEM) morphology image of Pt / p-GO@50-2min prepared in Example 2.

[0028] Figure 4 This is the TEM morphology of Pt / p-GO@12.5-2min prepared in Example 4.

[0029] Figure 5 This is the AC-TEM morphology of Pt / p-GO@12.5-2min prepared in Example 4.

[0030] Figure 6The linear voltammetric scan curve (LSV) performance diagram of the hydrogen evolution reaction catalyzed by the catalysts with different chloroplatinic acid addition amounts prepared in Examples 1-5, wherein 1 is the LSV curve of Pt / p-GO@100-2min prepared in Example 1, 2 is the LSV curve of Pt / p-GO@50-2min prepared in Example 2, 3 is the LSV curve of Pt / p-GO@25-2min prepared in Example 3, 4 is the LSV curve of Pt / p-GO@12.5-2min prepared in Example 4, and 5 is the LSV curve of Pt / p-GO@6.5-2min prepared in Example 5.

[0031] Figure 7 This is the TEM morphology of Pt / p-GO@50-1min prepared in Example 6.

[0032] Figure 8 This is the TEM morphology of Pt / p-GO@50-5min prepared in Example 7.

[0033] Fig. 9 These are LSV performance diagrams of the hydrogen evolution reaction catalyzed by the catalysts prepared in Examples 6, 7 and 2 at different plasma treatment times, wherein 1 is the LSV curve of Pt / p-GO@50-1min prepared in Example 6, 2 is the LSV curve of Pt / p-GO@50-2min prepared in Example 2, and 3 is the LSV curve of Pt / p-GO@50-5min prepared in Example 7.

[0034] Fig.10 This is the LSV performance diagram of the hydrogen evolution reaction catalyzed by 20wt% commercial platinum carbon catalyst (curve 1) and Pt / p-GO@50-2min (curve 2) prepared in Example 2.

[0035] Fig.11 These are the stability test results of Pt / p-GO@50-2min prepared in Example 2.

[0036] Fig.12 LSV performance diagram of the hydrogen evolution reaction catalyzed by Pt / p-GO@50-2min prepared in Example 2 (curve 1), the catalyst prepared in Comparative Example 1 (curve 2), the catalyst prepared in Comparative Example 2 (curve 3) and the catalyst prepared in Comparative Example 3 (curve 4). DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0038] In the following examples, graphene oxide powder was purchased from Nanjing Xianfeng Nanomaterial Technology Co., Ltd. with a product number of XF002-2.

[0039] The rest of the raw materials, reagents or processing techniques, unless otherwise specified, are conventional commercially available raw materials or conventional processing techniques in the art.

[0040] Embodiment 1:

[0041] A single atom and nanoparticle composite system catalyst with low platinum content, the specific synthesis process is as follows:

[0042] (1) Take 1 g of chloroplatinic acid hexahydrate, ultrasonically disperse it in 19.3 mL of deionized water to obtain a chloroplatinic acid solution mother liquor with a concentration of 100 mmol / L; take 1 mL of the chloroplatinic acid solution mother liquor, add 9 mL of deionized water, and ultrasonically disperse it to obtain a chloroplatinic acid solution with a concentration of 10 mmol / L.

[0043] (2) Take 30 mg of graphene oxide powder, spread it evenly in a petri dish, put it into a plasma chamber, and treat it with microwave plasma. The plasma treatment parameters are: background vacuum is 3 Pa, the total flow rate of argon and ammonia is 100 standard milliliters per minute, the flow ratio of argon and ammonia is 90:10, the discharge power is 200 W, and the treatment time is 15 minutes to obtain nitrogen-doped reduced graphene oxide. Weigh 20 mg of the treated powder and ultrasonically disperse it in a mixed solvent of 8 ml of deionized water and 2 ml of ethanol to obtain a 2 mg / mL uniformly dispersed graphene solution.

[0044] (3) Take 100 μL of the 10 mmol / L chloroplatinic acid solution prepared in step (1) and 2 mL of the graphene solution prepared in step (2), mix them, stir them magnetically for 4 hours, and ultrasonicate them for 30 minutes to obtain a uniformly dispersed catalyst precursor solution. The sample prepared with this ratio is named Pt / p-GO@100-2min.

[0045] (4) The precursor solution is freeze-dried to obtain a precursor powder; or 5 μL of the precursor solution is drop-coated on the surface of a glassy carbon electrode with a diameter of 3 mm, and naturally dried to obtain a precursor electrode; or 100 μL of the precursor solution is drop-coated on the surface of a 1×1 cm carbon paper, and naturally dried to obtain a self-supporting precursor electrode.

[0046] (5) The precursor powder or the two precursor electrodes obtained in step (4) are placed in a plasma chamber and treated with microwave plasma. The plasma parameters are: background vacuum is 3 Pa, the flow rate of argon is 200 standard milliliters per minute, the discharge power is 200 W, and the treatment time is 2 minutes.

[0047] The performance of the catalytic hydrogen evolution reaction of the sample prepared in Example 1 is as follows: Figure 6 As shown in 1.

[0048] Embodiment 2:

[0049] A single atom and nanoparticle composite system catalyst with low platinum content, the specific synthesis process is as follows:

[0050] The difference between the specific implementation method of this embodiment and that of Embodiment 1 is that in step (3), 50 μL of the 10 mmol / L chloroplatinic acid solution prepared in step (1) and 2 ml of the graphene solution prepared in step (2) are mixed, and the resulting product is named Pt / p-GO@50-2min. The other steps are the same as the specific implementation methods (1) to (5) of Embodiment 1.

[0051] The transmission electron microscope (TEM) morphology of the sample prepared in Example 2 is as follows: Figure 2 As shown, the morphology of spherical aberration corrected electron microscope (AC-TEM) is shown in Figure 3 The performance of the catalytic hydrogen evolution reaction is shown in Figure 6 As shown in 2.

[0052] Embodiment 3:

[0053] A single atom and nanoparticle composite system catalyst with low platinum content, the specific synthesis process is as follows:

[0054] The difference between the specific implementation method of this embodiment and that of Embodiment 1 is that in step (3), 25 μL of the 10 mmol / L chloroplatinic acid solution prepared in step (1) and 2 ml of the graphene solution prepared in step (2) are mixed, and the resulting product is named Pt / p-GO@25-2min. The other steps are the same as the specific implementation methods (1) to (5) of Embodiment 1.

[0055] The performance of the catalytic hydrogen evolution reaction of the sample prepared in Example 3 is as follows: Figure 6 As shown in 3.

[0056] Embodiment 4:

[0057] A single atom and nanoparticle composite system catalyst with low platinum content, the specific synthesis process is as follows:

[0058] The difference between the specific implementation method of this embodiment and that of Embodiment 1 is that in step (3), 12.5 μL of the 10 mmol / L chloroplatinic acid solution prepared in step (1) and 2 ml of the graphene solution prepared in step (2) are mixed, and the resulting product is named Pt / p-GO@12.5-2min. The other steps are the same as the specific implementation methods (1) to (5) of Embodiment 1.

[0059] The TEM morphology of the sample prepared in Example 4 is as follows: Figure 4 As shown, the AC-TEM morphology is as follows Figure 5 The performance of the catalytic hydrogen evolution reaction is shown in Figure 6 As shown in Figure 4.

[0060] Embodiment 5:

[0061] A single atom and nanoparticle composite system catalyst with low platinum content, the specific synthesis process is as follows:

[0062] The difference between the specific implementation method of this embodiment and that of Embodiment 1 is that in step (3), 6.5 μL of the 10 mmol / L chloroplatinic acid solution prepared in step (1) and 2 ml of the graphene solution prepared in step (2) are mixed, and the resulting product is named Pt / p-GO@6.5-2min. The other steps are the same as the specific implementation methods (1) to (5) of Embodiment 1.

[0063] The performance of the catalytic hydrogen evolution reaction of the sample prepared in Example 5 is as follows: Figure 6 As shown in Figure 5.

[0064] from Figure 1 The morphology of nitrogen-doped reduced graphene oxide after plasma treatment given in shows that the graphene sheets exist in the form of few layers, and there are some wrinkles on the surface, indicating that there are still some oxygen-containing groups on the surface. The few-layer structure of graphene greatly increases the surface area.

[0065] Comparing the TEM and AC-TEM morphology of the samples prepared in Example 2 and Example 4 ( Figure 2-5 ), when the amount of chloroplatinic acid added in the precursor is high, Figure 2 , 3, it can be observed that the sample prepared in Example 2 has both single atoms of platinum and nanoparticles on the graphene surface; when the amount of chloroplatinic acid added in the precursor is low, Figure 4 , it can be observed in Figure 5 that only single atoms of platinum exist on the graphene surface of the sample prepared in Example 4.

[0066] The catalytic hydrogen evolution reaction performance of the graphene-supported platinum-based catalysts prepared in Examples 1-5 above was studied. Figure 6 As shown, comparing the catalysts prepared in Example 1 with those prepared in Example 2, the amount of platinum used in the latter is only half of that in the former, but the performance is almost the same, indicating that the catalyst prepared in Example 2 can make the most of the precious metal platinum. Comparing the catalysts prepared in Example 5 with those prepared in Examples 1-4, the performance of the catalyst prepared in Example 5 is significantly reduced, indicating that when the loading of platinum is too low, there are too few sites participating in the hydrogen evolution reaction, resulting in a decrease in performance. It can be observed that when the platinum content of the sample prepared in Example 4 is reduced to 1 / 4 of the amount added in Example 2, it can maintain a high catalytic performance of the hydrogen evolution reaction under low current, but the performance under high current is poorer than that of the catalyst prepared in Example 2. The two catalysts reach 300 mA cm -2The overpotentials required for the current density are 245mV and 89mV respectively.

[0067] The difference in morphology and corresponding performance of the catalysts prepared in Example 2 and Example 4 can be explained by density functional calculation. Under the test conditions of small current density, single-atom platinum has better catalytic activity for hydrogen evolution reaction than platinum nanoparticles, and under the test of large current density, the catalytic performance of hydrogen evolution reaction of platinum nanoparticles is better. Therefore, the single-atom platinum catalyst prepared in Example 4 shows higher catalytic performance under the test of small current. The composite system catalyst of single-atom platinum and nanoparticles prepared in Example 2 can show excellent performance under both small current and large current density test conditions, and is more likely to be applied to the catalytic hydrogen evolution reaction at large current density.

[0068] Using the optimal amount of chloroplatinic acid added in Example 2, the effect of plasma treatment time on the catalytic hydrogen evolution reaction performance of graphene-supported platinum-based catalyst was studied, as shown in the following examples.

[0069] Embodiment 6:

[0070] A single atom and nanoparticle composite system catalyst with low platinum content, the specific synthesis process is as follows:

[0071] The difference between this embodiment and the specific implementation method of Example 2 is that the plasma treatment time in step (5) is 1 min, the obtained product is named Pt / p-GO@50-1min, and the other steps are the same as the specific implementation methods (1) to (5) of Example 2.

[0072] The TEM morphology of the sample prepared in Example 6 is as follows: Figure 7 The performance of the catalytic hydrogen evolution reaction is shown in Fig. 9 As shown in 1.

[0073] Embodiment 7:

[0074] A single atom and nanoparticle composite system catalyst with low platinum content, the specific synthesis process is as follows:

[0075] The difference between this embodiment and the specific implementation method of Example 2 is that the plasma treatment time in step (5) is 5 minutes, and the obtained product is named Pt / p-GO@50-5min. The other steps are the same as the specific implementation methods (1) to (5) of Example 2.

[0076] The TEM morphology of the sample prepared in Example 7 is as follows: Figure 8 The performance of the catalytic hydrogen evolution reaction is shown in Fig. 9 As shown in 3.

[0077] The morphology and catalytic performance of the graphene-supported platinum-based catalysts prepared in Examples 2, 6, and 7 above at the optimal chloroplatinic acid addition amount and at different plasma treatment times in step (5) were studied. Figure 7 As shown, the density of the platinum nanoparticles prepared in Example 6 is low, the particle size is small, and the reduction is insufficient. Figure 8 As shown, the platinum nanoparticles of the sample prepared in Example 7 reached a size of more than 3 nm and had obvious agglomeration, which was attributed to the particle aggregation and growth caused by the longer plasma treatment time. Fig. 9 The performance difference of catalytic hydrogen evolution reaction under different plasma treatment time is given. 2 is the catalyst prepared by Example 2, which has the best catalytic performance of hydrogen evolution reaction. The difference in catalyst performance is directly related to the morphology. Too short plasma treatment time cannot fully reduce the chloroplatinic acid in the precursor, and the density of the platinum nanoparticles obtained by reduction is low, so the performance is poor. The too long plasma treatment time can cause the growth of platinum nanoparticles. Under the same chloroplatinic acid addition conditions, the growth of particles reduces the specific surface area, thereby causing the reduction of performance. For the microwave plasma used in the embodiment of the present invention, the plasma treatment time in the best step (5) is 2min. If other plasmas and powers are used, the optimal treatment time will change.

[0078] The low-platinum-content single-atom and nanoparticle composite catalyst (Pt / p-GO@50-2min) prepared in Example 2 was used as the working electrode (cathode) of the hydrogen evolution reaction, the saturated silver chloride electrode was used as the reference electrode, and the carbon rod was used as the counter electrode (anode). The hydrogen evolution reaction test was carried out in 0.5M H2SO4. The starting potential of the catalyst was close to 0, and the current density was 10mA cm -2 , 300mAcm -2 , 1000mA cm -2 The overpotentials of the catalysts are 18mV, 89mV and 130mV respectively, which is the best performance reported for pure platinum-based catalysts so far. The platinum loading of the catalyst is much lower than the 20wt% of commercial platinum carbon, which greatly reduces the cost of the catalyst. Fig.10 It can be seen that the catalyst prepared by the present invention has a catalytic performance superior to that of commercial platinum carbon, especially at a high current density. In addition, the stability of the catalyst prepared in Example 2 in catalyzing the hydrogen evolution reaction at an industrial current density was studied. In the chronoamperometric test, a constant overpotential of 150 mV was applied to the cathode, and the current density of the cathode could be stabilized at 1400 mA cm -2 The performance of the catalyst prepared by the present invention is stable when working under industrial current density.

[0079] Comparative Example 1:

[0080] Compared with Example 1, most of the steps are the same except that the step of plasma treatment of graphene oxide powder is omitted. Fig.12 As shown in curve 2 in , the performance of the final catalyst is reduced because the graphene oxide powder that has not been treated with plasma contains more oxygen-containing groups and has poor conductivity, so the performance of the final catalyst is reduced.

[0081] Comparative Example 2:

[0082] Compared with Example 1, most of the steps are the same, except that in this embodiment: the atmosphere of the plasma treatment in step (2) is adjusted from a mixed gas of argon and ammonia to pure argon. Fig.12 As shown in curve 3 in FIG, the performance of the final catalyst is reduced because the graphene oxide is treated by pure argon discharge, the reduction thereof is insufficient, and nitrogen doping cannot be introduced, and the activity of the catalyst is finally reduced.

[0083] Comparative Example 3:

[0084] Compared with Example 1, most of the steps are the same except that the step of treating the precursor electrode with Ar plasma is omitted. Fig.12 As shown in curve 4 in , it is found that the untreated precursor electrode exhibits poor catalytic activity because the structure of platinum single atoms and nanoparticles is not formed on the graphene surface.

[0085] Embodiment 8:

[0086] Compared with Example 1, most of the above are the same, except that in this example: the flow ratio of plasma argon gas to ammonia gas in step (2) is 95:5.

[0087] Embodiment 9:

[0088] Compared with Example 1, most of the above are the same, except that in this example: the flow ratio of plasma argon gas to ammonia gas in step (2) is 80:20.

[0089] Embodiment 10:

[0090] Compared with Example 1, most of the contents are the same, except that in this example: the plasma treatment time in step (2) is adjusted to 1 min.

[0091] Embodiment 11:

[0092] Compared with Example 1, most of the contents are the same, except that in this example: the plasma treatment time in step (2) is adjusted to 30 min.

[0093] Embodiment 12:

[0094] Compared with Example 1, most of the above are the same, except that in this example: the plasma treatment time in step (2) is adjusted to 50W.

[0095] Embodiment 13:

[0096] Compared with Example 1, most of the above are the same, except that in this example: the plasma treatment time in step (2) is adjusted to 500W.

[0097] Embodiment 14:

[0098] Compared with Example 1, most of the contents are the same, except that in this embodiment: the solvent for dissolving nitrogen-doped reduced graphene oxide in step (2) is changed to anhydrous ethanol.

[0099] Embodiment 15:

[0100] Compared with Example 1, most of the contents are the same, except that in this embodiment: the solvent for dissolving nitrogen-doped reduced graphene oxide in step (2) is changed to deionized water.

[0101] Embodiment 16:

[0102] Compared with Example 1, most of the contents are the same, except that in this example: the plasma treatment power in step (5) is adjusted to 50 W.

[0103] Embodiment 17:

[0104] Compared with Example 1, most of the contents are the same, except that in this example: the plasma treatment power in step (5) is adjusted to 500W.

[0105] Embodiment 18:

[0106] Compared with Example 1, most of the contents are the same, except that in this example: the plasma treatment time in step (5) is adjusted to 0.5 min.

[0107] Embodiment 19:

[0108] Compared with Example 1, most of the contents are the same, except that in this example: the plasma treatment time in step (5) is adjusted to 10 min.

[0109] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a single atom and nanoparticle composite catalyst with low platinum content, characterized in that: The following steps are involved: (1) subjecting graphene oxide powder to a first plasma treatment to obtain nitrogen-doped reduced graphene oxide; (2) uniformly dispersing nitrogen-doped reduced graphene oxide and chloroplatinic acid in a solvent to obtain a dispersion, freeze-drying the dispersion to obtain a precursor powder, or coating the dispersion on a load electrode or a carbon paper surface and drying it naturally to obtain a precursor electrode; (3) placing the precursor powder or the precursor electrode in a vacuum chamber and performing a second plasma treatment to obtain a target product catalyst, or a target product catalyst covered on the surface of a support electrode or carbon paper; In the first plasma treatment process of step (1), the plasma used is a non-thermal equilibrium plasma, the discharge atmosphere is a mixed gas of argon and ammonia, and the background vacuum is 1-5 Pa; During the first plasma treatment, the flow ratio of argon to ammonia was 95:5 to 80:20; During the first plasma treatment in step (1), the discharge power is 50-500 W and the treatment time is 1-30 min. In step (2), the amount of chloroplatinic acid and nitrogen-doped reduced graphene oxide added satisfies: the mass content of platinum relative to the nitrogen-doped reduced graphene oxide is 0.5 wt% to 5 wt%, and the PtCl6 in the dispersion is 2- The molar concentration is 0.01~0.5 mmol / L; During the second plasma treatment in step (3), the plasma used is a non-thermal equilibrium plasma, the discharge atmosphere is argon, and the background vacuum is 1-5 Pa; During the second plasma treatment in step (3), the discharge power is 50-500 W and the plasma treatment time is 0.5-10 min. In step (2), the solvent is a mixed solvent of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water is (0-1):1, and the amount of ethanol added is not 0.

2. A single atom and nanoparticle composite system catalyst with low platinum content, which is prepared by the preparation method as claimed in claim 1.

3. The use of a single atom and nanoparticle composite system catalyst with low platinum content as claimed in claim 2, characterized in that: The catalyst is used for catalyzing hydrogen evolution reaction under industrial-grade current density.

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