A method for synthesizing a PtCo bimetallic magnetic nanocatalyst in situ by hydrogen overflow to efficiently catalyze hydrogen production from hydrolysis of ammonia borane

Abstract

The application relates to the technical field of noble metal nanocatalyst, and discloses a method for efficiently catalyzing hydrogen production by hydrolysis of ammonia borane by using hydrogen overflow in-situ synthesis of PtCo bimetallic magnetic nanocatalyst, and the bimetallic nanocatalyst is Pt / Co-MOF in-situ derived PtCo / C. The technical scheme can effectively avoid the air oxidation of non-noble metals in the synthesis process, the catalyst synthesis steps are simplified through the in-situ synthesis method, the catalyst is synthesized while efficiently catalyzing hydrogen production by hydrolysis of ammonia borane, and the problem of dependence on inert gas protection in the synthesis of metal catalysts is solved.

Description

Technical Field

[0001] This invention relates to the field of noble metal nanocatalyst technology, specifically to a method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen by in-situ synthesis of PtCo bimetallic magnetic nanocatalysts using hydrogen overflow. Background Technology

[0002] In recent years, hydrogen energy, as a secondary clean energy source, has become a preferred new clean energy source due to its wide availability, zero environmental pollution, and high calorific value. Efficient hydrogen storage and transportation technology is key to realizing the large-scale application of hydrogen energy. Among various hydrogen storage materials, ammonia borane has attracted much attention due to its high hydrogen content (19.6 wt%), non-toxicity, room temperature stability, and environmental friendliness. Developing efficient dehydrogenation catalysts is a crucial factor in promoting the large-scale application of ammonia borane.

[0003] Currently, the most commonly used catalysts for the catalytic production of hydrogen from ammonia borane are noble metal-non-noble metal composite catalysts. However, during the synthesis of these bimetallic catalysts, the non-noble metals are easily oxidized by air, severely affecting the catalyst's performance. Therefore, there is an urgent need to develop a catalyst and preparation method that can effectively avoid the oxidation problem of non-noble metals during the synthesis of noble metal-non-noble metal composite catalysts. Summary of the Invention

[0004] The present invention aims to provide a method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen by synthesizing PtCo bimetallic magnetic nanocatalysts in situ using hydrogen overflow, thereby solving the problem that non-precious metals are easily oxidized during the synthesis of catalysts for hydrogen production from ammonia borane in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen by in-situ synthesis of PtCo bimetallic magnetic nanocatalysts using hydrogen overflow, wherein the bimetallic magnetic nanocatalyst is PtCo / C derived in-situ from Pt / Co-MOF.

[0006] Preferably, as an improvement, the preparation method of Pt / Co-MOF nanocatalyst includes the following steps:

[0007] Step 1: Terephthalic acid and Co(NO3)2·6H2O are ultrasonically synthesized at room temperature to form Co-MOF;

[0008] Step 2: Co-MOF reacts with H2PtCl6 to obtain Pt / Co-MOF.

[0009] Preferably, as an improvement, in step one, phthalic acid is dissolved in a mixed solvent of DMF, deionized water and ethanol, and then Co(NO3)2·6H2O is added. TEA is added under stirring to form a colloidal suspension, and then the suspension is sealed and ultrasonically treated at room temperature.

[0010] Preferably, as an improvement, in step one, the mass ratio of DMF, deionized water and ethanol in the mixed solvent is 10-30:1-3:1-3.

[0011] Preferably, as an improvement, the ultrasonic treatment time in step one is 4 to 8 hours.

[0012] Preferably, as an improvement, in step one, after ultrasonic treatment, the product is washed with ethanol, centrifuged, and dried to obtain Co-MOF.

[0013] Preferably, as an improvement, in step two, after adding H2PtCl6 solution to the Co-MOF dispersion in ethanol, the mixture is heated and stirred at 60-70°C for 4-8 hours, and finally washed with ethanol, centrifuged and dried to obtain Pt / Co-MOF.

[0014] Preferably, as an improvement, in step two, the mass ratio of Co-MOF to ethanol is 0.2 to 2:1.

[0015] Preferably, as an improvement, in both steps one and two, the washing and centrifugation are performed three times, and the centrifugation speed is 8000-14000 r / min.

[0016] Preferably, as an improvement, in steps one and two, the catalyst is dried until it is in the form of flakes.

[0017] The principle and advantages of this scheme are as follows: In practical applications, this technical scheme addresses the issue that non-noble metals are easily oxidized during synthesis. It proposes a novel method to improve the hydrogen production performance of ammonia borane hydrolysis by in-situ synthesis of Pt / Co bimetallic magnetic nanocatalysts using hydrogen overflow: Pt is loaded onto a two-dimensional Co-MOF using the weak reducing property of ethanol to form a Pt / Co-MOF nanocatalyst without damaging the Co-MOF structure. When using Pt / Co-MOF to catalyze the hydrolysis of ammonia borane to produce hydrogen, the active hydrogen species generated by the dissociation of the noble metal Pt from ammonia borane can overflow onto the Co-MOF, destroying the MOF structure while simultaneously releasing the Co content within the MOF structure. 2+The species is reduced to metallic Co, resulting in a novel PtCo / C bimetallic magnetic nanocatalyst that efficiently catalyzes hydrogen production from ammonia borane. This in-situ reduction method effectively avoids the oxidation of non-noble metals by air during synthesis. The in-situ synthesis method simplifies the catalyst synthesis steps, achieving efficient hydrogen production from ammonia borane while synthesizing the catalyst, and solving the problem of relying on inert gas protection in the synthesis of metal catalysts.

[0018] Furthermore, in optimizing the preparation process of Pt / Co-MOF nanocatalysts, the inventors creatively employed a room-temperature ultrasonic synthesis method, unlike the commonly used hydrothermal synthesis process in existing technologies. This reduced the difficulty of synthesis and simplified the method. Moreover, in existing technologies, Pt is typically loaded onto Co-MOFs using methods such as NaBH4 or high-temperature H2 reduction, which easily destroys the Co-MOF structure. PtCo bimetallic catalysts obtained through this non-in-situ reduction method are easily oxidized during the transfer process. In this scheme, however, MOF is used as the support, eliminating the need for pretreatment (most existing technologies involve high-temperature forging or using strong reducing agents to convert MOFs into carbon). Instead, the hydrogen spillover effect generated by the dissociation of noble metals from ammonia borane transforms the MOF structure in situ into a carbon support. This not only ensures the high catalytic activity of the Pt / Co-MOF nanocatalysts but also demonstrates good catalytic stability in stability tests, which is of significant importance in the industry. Attached Figure Description

[0019] Figure 1 This is a comparison chart of the catalytic activities of Co / MOF, Pt / Co-MOF, Pt / Co-MOF-1, and Pt / Ni-MOF in the embodiments of the present invention.

[0020] Figure 2 In the embodiments of the present invention, Pt / ZIF-67, Pt / ZIF-8, and Pt 1％ / ZIF-67 and Pt 1％ / ZIF-8 catalytic activity comparison chart.

[0021] Figure 3 This is a comparison chart of the first and second reaction performances of Pt / Co-MOF in an embodiment of the present invention.

[0022] Figure 4 This is a comparison chart of the reaction performance of NaBH4 and H2 pretreatment and the second reaction of Pt / Co-MOF in the embodiments of the present invention.

[0023] Figure 5 The images show the transmission electron microscope (TEM) image and EDX spectrum of the Pt / Co-MOF catalytic reaction before the reaction.

[0024] Figure 6 The images show transmission electron microscopy (TEM) images and EDX spectra of the Pt / Co-MOF catalytic reaction. Detailed Implementation

[0025] The following detailed description provides further details on specific embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; and the materials and reagents used are all commercially available.

[0026] Overview of the plan:

[0027] A method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen using a PtCo bimetallic magnetic nanocatalyst synthesized in situ via hydrogen overflow includes the following steps:

[0028] Step 1: Preparation of Co-MOF: Weigh 125 mg of terephthalic acid and dissolve it in 30 mL of DMF, 2 mL of deionized water, and 2 mL of ethanol. Then, add 220 mg of Co(NO3)2·6H2O to the above solution, and rapidly inject 1 mL of TEA under vigorous stirring to form a homogeneous colloidal suspension. After sealing, sonicate for 6 h. Subsequently, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Co-MOF.

[0029] Step 2: Preparation of Pt / Co-MOF: Weigh 120 mg of Co-MOF and uniformly disperse it in 120 mL of ethanol. Add 12.2 μL of H2PtCl6 (0.1 M) solution, stir for 15 min, and then continue heating and stirring at 65 °C for 5 h. Finally, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Pt / Co-MOF.

[0030] Step 3, Catalytic hydrolysis of ammonia borane: Weigh 20 mg of the prepared Pt / Co-MOF and add it to a 25 mL sealed round-bottom flask. Disperse it in 4 mL of deionized water and stir evenly. Then add 1 mL of deionized water containing 30.8 mg of ammonia borane to carry out the reaction.

[0031] Experimental detection methods:

[0032] The hydrogen production reaction of ammonia borane hydrolysis was tested using the water displacement method: Under normal pressure, a certain amount of catalyst (20 mg) was placed in a 25 mL sealed round-bottom flask and immersed in a water bath to control the reaction temperature. 4 mL of deionized water was added and the mixture was stirred thoroughly to disperse the catalyst evenly. Then, 30.8 mg (1 mmol) of ammonia borane was dissolved in 1 mL of deionized water and added to the round-bottom flask. The reaction was started and timed. A graduated U-tube filled with water was used to detect the volume of hydrogen produced. As the reaction proceeded, the change in the graduations of the U-tube (hydrogen production volume) over time was recorded.

[0033] Example 1

[0034] A method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen using a PtCo bimetallic magnetic nanocatalyst synthesized in situ via hydrogen overflow includes the following steps:

[0035] Step 1: Weigh 125 mg of terephthalic acid and dissolve it in 30 mL of DMF, 2 mL of deionized water, and 2 mL of ethanol. Then, add 220 mg of Co(NO3)2·6H2O to the above solution, and rapidly inject 1 mL of TEA under vigorous stirring to form a homogeneous colloidal suspension. Seal and sonicate for 6 h. Subsequently, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h. Weigh 120 mg of Co-MOF and uniformly disperse it in 120 mL of ethanol. Add 12.2 μL of H2PtCl6 (0.1 M) solution, stir for 15 min, and continue heating and stirring at 65 °C for 5 h. Finally, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Pt / Co-MOF.

[0036] Step 2: Weigh 20 mg of the prepared Pt / Co-MOF and add it to a 25 mL sealed round-bottom flask. Disperse the Pt / Co-MOF in 4 mL of deionized water and stir until homogeneous. Then add 1 mL of deionized water containing 30.8 mg of ammonia borane and start the reaction, timing the reaction. Based on the total Pt atomic weight (loading of 0.2%), the conversion efficiency (TOF) was calculated to be 3400 mol / L. H2 ·mol Pt ·min -1 .

[0037] Step 3: After the first reaction, the catalyst was completely reduced to PtCo / C. After adding the same amount of ammonia borane again, the conversion efficiency (TOF) was calculated to be 4219 mol / L. H2 ·mol Pt ·min -1 .

[0038] Example 2

[0039] The difference between this embodiment and Embodiment 1 is that the mass ratio of DMF, deionized water and ethanol in this embodiment is 30:1:1; the ultrasonic treatment time after sealing is 4 hours; and the mass ratio of Co-MOF to ethanol is 0.2:1.

[0040] Example 3

[0041] The difference between this embodiment and Embodiment 1 is that the mass ratio of DMF, deionized water and ethanol in this embodiment is 10:1:1; the ultrasonic treatment time after sealing is 48 hours; and the mass ratio of Co-MOF to ethanol is 2:1.

[0042] Comparative Example 1

[0043] In this comparative example, the Pt / Co-MOF catalyst in Example 1 was replaced with a Co-MOF catalyst to catalyze the hydrolysis of ammonia borane to produce hydrogen. The specific steps include the following:

[0044] Step 1: 1. Weigh 125 mg of terephthalic acid and dissolve it in 30 mL of DMF, 2 mL of deionized water, and 2 mL of ethanol. Then, add 220 mg of Co(NO3)2·6H2O to the above solution, and rapidly inject 1 mL of TEA under vigorous stirring to form a homogeneous colloidal suspension. After sealing, sonicate for 6 h. Subsequently, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Co-MOF.

[0045] Step 2: Weigh 20 mg of the prepared Co-MOF and add it to a 25 mL sealed round-bottom flask. Disperse the mixture in 4 mL of deionized water and stir until homogeneous. Then add 1 mL of deionized water containing 30.8 mg of ammonia borane and start the reaction, timing it. After a period of time, the reaction showed no catalytic activity.

[0046] Comparative Example 2

[0047] The difference between this comparative example and Example 1 is that this comparative example uses a hydrothermal synthesis method commonly used in the prior art to prepare Pt / Co-MOF, specifically including the following steps:

[0048] Step 1: 1. Add 0.238 g of CoCl2·6H2O and 0.166 g of terephthalic acid to 35 mL of DMF. Then, slowly add 2.5 mL of ethanol and water to the solution. After gentle stirring, transfer the clear solution to a 50 mL Teflon-lined stainless steel hydrothermal reactor and heat to 125 °C for 12 h. After natural cooling, centrifuge with ethanol at 10000 r / min, wash the precipitate several times, and dry at 60 °C for 6 h to obtain Co-MOF-1.

[0049] Step 2: Weigh 120 mg of Co-MOF-1 and uniformly disperse it in 120 mL of ethanol. Add 12.2 μL of H2PtCl6 (0.1 M) solution, stir for 15 min, and then continue heating and stirring at 65 °C for 5 h. Finally, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Pt / Co-MOF-1.

[0050] Step 3: Weigh 20 mg of the prepared Pt / Co-MOF-1 and add it to a 25 mL sealed round-bottom flask. Disperse the mixture in 4 mL of deionized water and stir until homogeneous. Then add 1 mL of deionized water containing 30.8 mg of ammonia borane and start the reaction, timing the reaction. Based on the total Pt atomic weight (loading of 0.2%), the conversion efficiency (TOF) is calculated to be 1400 mol / L. H2 ·mol Pt ·min -1 .

[0051] Comparative Example 3

[0052] In this comparative example, the catalyst is Pt / Ni-MOF, and the specific process of catalyzing the hydrolysis of ammonia borane to produce hydrogen includes the following steps:

[0053] Step 1: Weigh 125 mg of terephthalic acid and dissolve it in 30 mL of DMF, 2 mL of deionized water, and 2 mL of ethanol. Then, add 180 mg of NiCl2·6H2O to the above solution, and rapidly inject 1 mL of TEA under vigorous stirring to form a homogeneous colloidal suspension. After sealing, sonicate for 6 h. Subsequently, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Ni-MOF.

[0054] Step 2: Weigh 120 mg of Ni-MOF and uniformly disperse it in 120 mL of ethanol. Add 12.2 μL of H2PtCl6 (0.1 M) solution, stir for 15 min, and then continue heating and stirring at 65 °C for 5 h. Finally, wash with ethanol, centrifuge at 10000 r / min, collect the precipitate, and repeat three times to finally obtain Pt / Ni-MOF.

[0055] Step 3: Weigh 20 mg of the prepared Pt / Ni-MOF and add it to a 25 mL sealed round-bottom flask. Disperse the Pt / Ni-MOF in 4 mL of deionized water and stir until homogeneous. Then add 1 mL of deionized water containing 30.8 mg of ammonia borane and start the reaction, timing the reaction. Based on the total Pt atomic weight (loading of 0.2%), the TOF value of the reaction is calculated to be 620 mol / L. H2 ·mol Pt ·min -1 .

[0056] Comparative Example 4

[0057] In this comparative example, the catalyst is Pt / ZIF-67, and the specific catalytic process for the hydrolysis of ammonia borane to produce hydrogen includes the following steps:

[0058] Step 1: Dissolve 1.455 g of Co(NO3)2·6H2O and 1.642 g of 2-methylimidazole in a mixture of 40 mL of methanol and 40 mL of ethanol, respectively. Mix the two solutions rapidly for 5 min, allow to settle at room temperature for 24 h, then filter and collect the purple precipitate. Purify the precipitate repeatedly with ethanol. Finally, vacuum dry the obtained sample at 60 °C for 24 h to obtain ZIF-67.

[0059] Step 2: The method of loading Pt is the same as above, and Pt / ZIF-67 is finally obtained.

[0060] Step 3: Weigh 20 mg of the prepared Pt / ZIF-67 and add it to a 25 mL sealed round-bottom flask. Disperse the mixture in 4 mL of deionized water and stir until homogeneous. Then add 1 mL of deionized water containing 30.8 mg of ammonia borane and start the reaction, beginning the timer. The catalyst has almost no activity.

[0061] Comparative Example 5

[0062] In this comparative example, the catalyst is Pt / ZIF-8, and the specific process of catalyzing the hydrolysis of ammonia borane to produce hydrogen includes the following steps:

[0063] Step 1: Dissolve 0.28 mol (22.95 g) of 2-methylimidazole in 80 mL of water and stir at 35 °C to form a homogeneous solution. Then, weigh out 1.19 g (4.0 x 10⁻³ mol) of Zn(NO₃)₂·6H₂O and dissolve it in 9 mL of aqueous solution. Quickly mix the two aqueous solutions. After stirring the mixture for 1 h, wash and centrifuge several times with water and ethanol at 10000 r / min. Then, vacuum dry at 60 °C overnight to obtain ZIF-8.

[0064] Step 2: The method of loading Pt is the same as above, and finally Pt / ZIF-8 is obtained.

[0065] Step 3: Weigh 20 mg of the prepared Pt / ZIF-8 and add it to a 25 mL sealed round-bottom flask. Disperse the Pt / ZIF-8 in 4 mL of deionized water and stir until homogeneous. Then add 1 mL of deionized water containing 30.8 mg of ammonia borane and start the reaction, beginning the timer. The catalyst has almost no activity.

[0066] Comparative Example 6

[0067] In this comparative example, NaHB4 pretreatment was added before the Pt / Co-MOF catalytic hydrolysis of ammonia borane to produce hydrogen. The specific steps included the following:

[0068] Step 1: Weigh 125 mg of terephthalic acid and dissolve it in 30 mL of DMF, 2 mL of deionized water, and 2 mL of ethanol. Then, add 220 mg of Co(NO3)2·6H2O to the above solution, and rapidly inject 1 mL of TEA under vigorous stirring to form a homogeneous colloidal suspension. After sealing, sonicate for 6 h. Subsequently, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Co-MOF.

[0069] Step 2: Weigh 120 mg of Co-MOF and uniformly disperse it in 120 mL of ethanol. Add 12.2 μL of H2PtCl6 (0.1 M) solution, stir for 15 min, and then continue heating and stirring at 65 °C for 5 h. Finally, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Pt / Co-MOF.

[0070] Step 3: Weigh 20 mg of the prepared Pt / Co-MOF and add it to a 25 mL sealed round-bottom flask. Disperse it in 3 mL of deionized water and stir until homogeneous. Add 1 mL of sodium borohydride solution (1 M) for pretreatment. After stirring until homogeneous, add 1 mL of deionized water containing 30.8 mg of ammonia borane and start the reaction and start timing.

[0071] Comparative Example 7

[0072] In this comparative example, H2 pretreatment was added before the Pt / Co-MOF-catalyzed hydrolysis of ammonia borane to produce hydrogen. The specific steps included the following:

[0073] Step 1: Weigh 125 mg of terephthalic acid and dissolve it in 30 mL of DMF, 2 mL of deionized water, and 2 mL of ethanol. Then, add 220 mg of Co(NO3)2·6H2O to the above solution, and rapidly inject 1 mL of TEA under vigorous stirring to form a homogeneous colloidal suspension. After sealing, sonicate for 6 h. Subsequently, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Co-MOF.

[0074] Step 2: Weigh 120 mg of Co-MOF and uniformly disperse it in 120 mL of ethanol. Add 12.2 μL of H2PtCl6 (0.1 M) solution, stir for 15 min, and then continue heating and stirring at 65 °C for 5 h. Finally, wash and centrifuge three times with ethanol at 10000 r / min, and dry at 65 °C for 12 h to obtain Pt / Co-MOF.

[0075] Step 3: Pre-treat 20 mg of the prepared Pt / Co-MOF at 500 °C for 4 h under H2 conditions. After treatment, add the catalyst to a 25 mL sealed round-bottom flask, disperse it in 4 mL of deionized water and stir evenly. Then add 1 mL of deionized water containing 30.8 mg of ammonia borane and start the reaction and start timing.

[0076] Experimental Example 1

[0077] The catalytic activity of Pt-based catalysts with Co-MOF and different metal-organic frameworks (Pt loading maintained at 0.2%) for the hydrolysis of ammonia borane was assessed (i.e., the catalysts of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 catalyzed the hydrolysis of ammonia borane solution (0.2 mol L / L) at 25 °C). -1 A comparative analysis was conducted on the volume of H2 generated, and the results are as follows: Figure 1 As shown. Figure 1 The results showed that the catalysts of Example 1, Comparative Example 2, and Comparative Example 3 all had the ability to catalyze the hydrogen production of ammonia borane. The Pt / Co-MOF catalyst of Example 1 had the fastest hydrogen production rate of ammonia borane, while the Co-MOF catalyst of Comparative Example 1 showed almost no catalytic activity. This indicates that Pt species are the main active sites responsible for the hydrolysis of ammonia borane.

[0078] Experimental Example 2

[0079] To better compare the catalytic performance of Pt-based catalysts supported on different metal-organic frameworks, ZIF-67 and ZIF-8, two representative MOF materials, were used as Pt supports, and the effect of different loading amounts on catalytic activity was investigated. The results are as follows: Figure 2 As shown, the H2 production curve of the Pt / ZIF-67 catalyst exhibits a relatively long induction period, approximately 20 min, after which the H2 production curve begins to gradually increase. The Pt / ZIF-8 catalyst maintains a hydrogen production volume of 0 after 30 min of reaction. When the Pt loading is increased to 1%, the ammonia borane in Pt… 1％ Hydrolysis on / ZIF-67 achieved a conversion rate of approximately 100% within 15 minutes, and Pt 1％ The hydrogen production curve of / ZIF-8 began to gradually rise after an induction period of approximately 10 min. These results indicate that both Pt and MOF may play important roles in the dehydrogenation of ammonia borane. Notably, all Pt-based catalysts exhibit an initial induction period, during which new active species are generally believed to be generated.

[0080] Experimental Example 3

[0081] To investigate the stability of the Pt / Co-MOF catalyst in Example 1 of this invention, the Pt / Co-MOF was subjected to the first five catalytic reactions in an ammonia borane solution (0.2 mol L⁻¹) at 25 °C. -1A comparative analysis was conducted on the volume of H2 generated, and the results are as follows: Figure 3 As shown, the results indicate that the catalytic activity remains high after five cycles, the catalytic performance is stable, and the induction period at the start of the second reaction disappears.

[0082] Experiment Example 4

[0083] The effects of Example 1, Comparative Example 6, and Comparative Example 7 on the catalytic hydrolysis of ammonia borane to produce hydrogen were compared and analyzed. The results are as follows: Figure 4 As shown, the results indicate that the catalytic activity is weak after H2 pretreatment, while in-situ reduction and treatment with sodium borohydride solution exhibit better catalytic activity for the hydrolysis of ammonia borane. In-situ treatment can reach the catalytic peak in a relatively short time.

[0084] Experimental Example 5

[0085] Transmission electron microscopy and X-ray diffraction were performed before and after the Pt / Co-MOF catalytic reaction, and the results are as follows: Figure 5 , Figure 6 As shown, where, Figure 5 -a is a transmission electron microscope image of Pt / Co-MOF catalytic reaction before the reaction; Figure 5 -b represents the EDX spectrum before the Pt / Co-MOF catalytic reaction; Figure 5 -c is the EDX elemental distribution diagram before the Pt / Co-MOF catalytic reaction; Figure 6 -a shows the magnetic properties and color comparison of Pt / Co-MOF before and after a primary catalytic reaction; Figure 6 -b represents the X-ray diffraction patterns of Pt / Co-MOF before and after the primary catalytic reaction; Figure 6 -c is a transmission electron microscope image of Pt / Co-MOF after a primary catalytic reaction; Figure 6 -d is a high-resolution transmission electron microscope image of Pt / Co-MOF after a single catalytic reaction.

[0086] The results showed that the Pt / Co-MOF had a sheet-like structure, and no obvious nanoparticles could be observed. After one reaction, the Co in the catalyst was reduced, thus exposing the metal particles. This was a result of the hydrogen overflow generated by the dissociation of Pt from ammonia borane, which destroyed the Co-MOF.

[0087] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen using a PtCo bimetallic magnetic nanocatalyst synthesized in situ via hydrogen overflow, characterized in that: The bimetallic magnetic nanocatalyst is a Pt / Co / C nanocatalyst derived in situ from Pt / Co-MOF; The preparation method of Pt / Co-MOF includes the following steps: Step 1: Dissolve phthalic acid in a mixed solvent of DMF, deionized water and ethanol, then add Co(NO3)2·6H2O, and add TEA under stirring to form a colloidal suspension. Then, seal and sonicate at room temperature to synthesize Co-MOF. Step 2: Co-MOF reacts with H2PtCl6 to obtain Pt / Co-MOF; In step two, Co-MOF is dispersed in ethanol, H2PtCl6 solution is added, and the mixture is heated and stirred at 60-70℃ for 4-8 hours. Finally, it is washed with ethanol, centrifuged, and dried to obtain Pt / Co-MOF. In step two, the mass ratio of Co-MOF to ethanol is 0.2-2:

1.

2. The method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen using a PtCo bimetallic magnetic nanocatalyst synthesized in situ via hydrogen overflow, as described in claim 1, is characterized in that: In step one, the mass ratio of DMF, deionized water and ethanol in the mixed solvent is 10-30:1-3:1-3.

3. The method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen using a PtCo bimetallic magnetic nanocatalyst synthesized in situ via hydrogen overflow, as described in claim 2, is characterized in that: In step one, the ultrasonic treatment time is 4-8 hours.

4. The method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen using a PtCo bimetallic magnetic nanocatalyst synthesized in situ via hydrogen overflow, as described in claim 3, is characterized in that: In step one, after ultrasonic treatment, the product is washed with ethanol, centrifuged, and dried to obtain Co-MOF.

5. The method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen using a PtCo bimetallic magnetic nanocatalyst synthesized in situ via hydrogen overflow, as described in claim 1, is characterized in that: In both steps one and two, the washing and centrifugation are performed three times, and the centrifugation speed is 8000-14000 r / min.

6. The method for efficiently catalyzing the hydrolysis of ammonia borane to produce hydrogen using a PtCo bimetallic magnetic nanocatalyst synthesized in situ via hydrogen overflow, as described in claim 5, is characterized in that: In steps one and two, the catalyst is dried until it forms flakes.

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