Nanocatalyst for decomposing hydrazine hydrate to produce hydrogen, preparation method and application thereof

Abstract

The present invention belongs to the technical field of hydrogen storage materials, and specifically relates to a nanocatalyst for producing hydrogen by decomposing hydrazine hydrate, and its preparation method and application. The nanocatalyst is composed of NiPt nanoparticles uniformly dispersed in Li + Intercalated two-dimensional layered Ti3C2T x The chemical formula is NiPt / (Li + )‑Ti3C2T x The present invention is achieved by Li + Intercalation treatment makes Ti3C2T x Expose more surface functional groups, thereby enhancing its adsorption capacity for metal precursor salt ions, regulating the electronic structure of the metal, and loading NiPt nanoparticles on (Li + )‑Ti3C2T x It can effectively improve the dispersibility of metal nanoparticles and reduce the particle size, so that the prepared catalytic material has high electron density, many catalytic active sites and high cyclic stability. It is a catalyst with development prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen storage materials, and in particular relates to a nanocatalyst for decomposing hydrazine hydrate to produce hydrogen, and a preparation method and application thereof. Background Art

[0002] Hydrogen is considered one of the new clean energy sources with the potential to replace fossil fuels in the future. However, the storage and transportation of hydrogen severely restricts the further development of a hydrogen economy. Finding appropriate strategies to address these challenges is essential and crucial. Chemical hydrogen storage materials have attracted widespread attention due to their high hydrogen content and mild dehydrogenation temperature.

[0003] As a monohydrate of hydrazine, hydrazine hydrate undergoes a decomposition process identical to that of hydrazine. Furthermore, hydrazine hydrate (N₂H₄·H₂O) has a high hydrogen content (8.0 wt%) and can completely decompose to form nitrogen and hydrogen under appropriate conditions (Equation (1)). However, under an inappropriate catalytic system, hydrazine hydrate decomposes to form ammonia and nitrogen, reducing hydrogen production and causing environmental damage (Equation (2)).

[0004] N2H4(l)→N2(g)+2H 2( g) (1)

[0005] 3N2H4(l)→4NH 3( g)+N2(g) (2)

[0006] As early as 2011, Xu's research group developed monometallic Rh NPs for hydrogen production from hydrazine hydrate decomposition (J.Am.Chem.Soc., 131(2009):9894-9895), but the catalyst could not achieve 100% hydrogen selectivity. They then incorporated a certain amount of Ni into the Rh NPs catalyst (J.Am.Chem.Soc., 131(2009):18032-18033). The incorporation of Ni can form a synergistic effect and greatly improve the activity and hydrogen selectivity of the catalyst. Since then, a series of hydrazine hydrate hydrogen production catalysts have been developed, but they often have low hydrogen production activity or even cannot completely catalyze the decomposition of hydrazine hydrate. Therefore, the development of catalysts with high efficiency, high stability and high hydrogen selectivity is crucial to accelerate the use of hydrazine hydrate as an industrial chemical hydrogen storage material. Summary of the Invention

[0007] The purpose of the present invention is to address the deficiencies in the prior art and provide a nanocatalyst for hydrogen production from hydrazine hydrate decomposition, a preparation method thereof, and an application thereof, specifically adopting the following technical solutions:

[0008] According to a first aspect of the present invention, a nanocatalyst for decomposing hydrazine hydrate to produce hydrogen is provided, wherein the nanocatalyst is composed of NiPt nanoparticles uniformly dispersed in Li + Intercalated two-dimensional layered Ti3C2T x The chemical formula of the nanocatalyst is Ni Pt / (Li + )-Ti3C2T x .

[0009] The present invention uses Ti3C2T x As a carrier, it has excellent electron transport structure and relative stability. x The carbon main layer has a large number of functional groups at the surface termination, which can be used to anchor metal nanoparticles or further synthesize other composite materials. It is a two-dimensional nanomaterial with great development potential. + Ti3C2T x The spontaneous intercalation treatment effectively increases the interlayer spacing and the number of exposed surface functional groups, thereby enhancing its adsorption capacity for metal precursor salt ions and regulating the electronic structure of the metal. These negatively charged surface functional groups easily combine with positively charged active metals. After reduction by a reducing agent, the nanoparticles can be well dispersed on the carrier. In addition, the excess electrons on the functional groups will be transferred to the active metal to form an electron-rich catalyst, further increasing the catalytic performance. When NiPt nanoparticles are loaded on Ti3C2T x It can effectively improve the dispersibility of metal nanoparticles and reduce the particle size, obtain electron-rich metal nanoclusters, form metal-support interactions, and thus make the prepared NiPt / (Li + )-Ti3C2T x The catalyst has excellent performance, with small and uniform particle size, high electron density, and multiple catalytic active sites. It can efficiently catalyze the decomposition of hydrazine hydrate to produce hydrogen with a selectivity of 100% and a conversion frequency (TOF) of up to 3200h under alkaline conditions at 323K. -1 , and has high cycle stability, and is a catalyst with development prospects.

[0010] As a further preferred embodiment, the Ni content in the nanocatalyst is greater than 0 and less than 8.9wt%, and the Pt content is greater than 0 and less than 24.5wt%. When the metal content is low, the frequency of contact between the active metal and the reactants is reduced, resulting in lower catalytic activity. However, when the metal content is too high, the active metal is difficult to disperse, which can also lead to a decrease in catalytic activity. Therefore, an appropriate loading is beneficial to improving catalyst activity.

[0011] As a further preferred embodiment, the molar ratio of Ni to Pt in the nanocatalyst is 6:4. The catalytic reaction rate of the nanocatalyst shows a trend of first increasing and then decreasing with increasing Ni to Pt molar ratio, indicating a strong synergistic effect between Ni and Pt. When the molar ratio of Ni to Pt is 6:4, the nanocatalyst exhibits optimal performance for hydrogen production from the decomposition of hydrazine hydrate.

[0012] As a further preferred embodiment, the average particle size of the NiPt nanoparticles is 1.8 nm ± 0.2 nm. Ultrafine NiPt nanoparticles with an average particle size of about 1.8 nm are highly dispersed in (Li + )-Ti3C2T x Therefore, the final prepared nanocatalyst has small and uniform particle size and strong electronic effect.

[0013] The present invention also provides a method for preparing a nanocatalyst for decomposing hydrazine hydrate to produce hydrogen, comprising the following steps:

[0014] First, Ti3C2T x The powder is dispersed in water, lithium chloride is added for ultrasonic intercalation treatment, and then centrifuged and separated to obtain an intermediate product; the intermediate product is then dispersed in water, nickel source precursor and platinum source precursor are added, ultrasonicated at room temperature, and after the reaction is completed, sodium borohydride is added for reduction reaction until no bubbles are generated, and finally NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0015] As a further preferred embodiment, Ti3C2T x The dosage ratio of lithium chloride and sodium borohydride is 10mg-40mg: 1.0mmol-15.0mmol: 25mg. x When the dosage is very small, the selectivity and activity of the catalyst are relatively low. This is mainly because the amount of carrier is too small, resulting in an excessively high active metal loading, and the metal nanoparticles cannot be dispersed, so the catalytic performance is poor. However, when the amount of carrier is too much, the active metal is not easy to contact with hydrazine hydrate, and the performance is reduced. The catalytic efficiency of the nanocatalyst increases first and then decreases with the increase of the amount of intercalation agent lithium chloride. However, when the amount of lithium chloride is too much, it will destroy the Ti3C2T x The structure is not conducive to the reduction and dispersion of nanoparticle size, making the final NiPt / (Li + )-Ti3C2T xThe catalytic performance of the nanocatalyst decreases during the reaction; if the amount of sodium borohydride in the catalyst is too small, the metal ions may not be completely reduced, resulting in a decrease in catalyst activity. However, when the amount of sodium borohydride is too large, its strong reducing property will destroy the unstable Ti-C structure in the MXene material, resulting in a decrease in its activity.

[0016] As a further preferred embodiment, the Ti3C2T x The ratio of lithium chloride and sodium borohydride is 30mg:5mmol:25mg. The inventors found that when the carrier Ti3C2T x When the dosage increases to 30 mg, the catalyst has the best catalytic activity; when the dosage of lithium chloride is 5.0 mmol, the nanocatalyst shows the best performance in decomposing hydrazine hydrate to produce hydrogen.

[0017] As a further preferred embodiment, the Ti3C2T x It is obtained by the following steps:

[0018] Lithium fluoride was dispersed in 9.0M hydrochloric acid solution and then titanium aluminum carbide was added and stirred at 40 °C for 48 hours. After the stirring, it was washed with water until neutral and vacuum dried to obtain Ti3C2T x .

[0019] In the above preparation method, the nickel source precursor is at least one of nickel chloride, nickel nitrate, or nickel sulfate; the platinum source precursor is at least one of platinum tetrachloride, potassium tetrachloroplatinate, and hexachloroplatinic acid.

[0020] The nanocatalyst for hydrogen production from hydrazine hydrate prepared by the present invention can be used in the preparation of hydrogen sources for fuel cells. When the catalyst is used to catalyze the decomposition of hydrazine hydrate to produce hydrogen, the temperature is 303K to 333K. Since the catalytic reaction is carried out in solution, excessively high temperatures will cause water evaporation, increase the concentration of hydrazine hydrate, and make the decomposition of hydrazine hydrate more difficult. Therefore, the catalytic temperature should not be too high.

[0021] The beneficial effects of the present invention are as follows: + Ti3C2T x The spontaneous intercalation process increases the Ti3C2T x The number of surface functional groups enables the carrier to effectively adsorb metal precursor salt ions, and the synthesized NiPt nanoparticles are loaded on the two-dimensional Ti3C2T treated with lithium ion intercalation. x It can effectively improve the dispersibility of metal nanoparticles and reduce the particle size, obtain electron-rich metal nanoclusters, form metal-support interactions, and thus prepare the NiPt / (Li + )-Ti3C2T xThe catalyst has excellent performance, with small and uniform particle size, high electron density, and multiple catalytic active sites. It can efficiently catalyze the decomposition of hydrazine hydrate to produce hydrogen with a selectivity of 100% and a conversion frequency (TOF) of up to 3200h under alkaline conditions at 323K. -1 , and has high cyclic stability. It is a catalyst with development prospects, which solves the problems of low catalytic activity and easy agglomeration of traditional catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 Shown are Ni obtained in Examples 1-6 y Pt 1-y / (Li + )-Ti3C2T x Nanocatalysts and (Li + )-Ti3C2T x X-ray diffraction pattern of;

[0024] Figure 2 The NiPt / (Li + )-Ti3C2T x Nanocatalysts and Ti3C2T x ,(Li + )-Ti3C2T x and NiPt / Ti3C2T x Raman spectrum of

[0025] Figure 3 The NiPt / (Li + )-Ti3C2T x Nanocatalysts and Ti3C2T x ,(Li + )-Ti3C2T x and NiPt / Ti3C2T x Fourier transform infrared spectrum of

[0026] Figure 4 The NiPt / (Li + )-Ti3C2T x Nanocatalysts and Ti3C2T x ,(Li + )-Ti3C2Tx and NiPt / Ti3C2T x Nitrogen adsorption test chart;

[0027] Figure 5 The NiPt / (Li + )-Ti3C2T x Transmission electron microscopy (TEM) image of the nanocatalyst (a), nanoparticle size distribution (b), selected area electron diffraction (SAED) image (c), and high-resolution TEM image (d);

[0028] Figure 6 The NiPt / (Li + )-Ti3C2T x EDX spectrum of nanocatalyst;

[0029] Figure 7 The NiPt / (Li + )-Ti3C2T x Nanocatalysts and NiPt / Ti3C2T x , NiPt / (Na + )-Ti3C2T x and NiPt / (K + )-Ti3C2T x X-ray photoelectron spectrum of

[0030] Figure 8 Shown is the Ni obtained in Example 1-6 y Pt 1-y / (Li + )-Ti3C2T x Performance test diagram of the composite catalyst for hydrogen production from the decomposition of hydrazine hydrate at 323K;

[0031] Figure 9 The NiPt / (Li + )-Ti3C2T x Performance test diagram of nanocatalyst catalyzing the decomposition of hydrazine hydrate at 323K;

[0032] Figure 10 The NiPt / (Li + )-Ti3C2T x Performance test diagram of nanocatalyst catalyzing the decomposition of hydrazine hydrate at 323K;

[0033] Figure 11 The NiPt / (Li + )-Ti3C2T xPerformance test diagram of nanocatalyst catalyzing the decomposition of hydrazine hydrate at different temperatures;

[0034] Figure 12 The NiPt / (Li + )-Ti3C2T x Figure 2. Test diagram of the recycling performance of nanocatalyst in catalyzing the decomposition of hydrazine hydrate at 323K. DETAILED DESCRIPTION

[0035] The following will provide a clear and complete description of the concept, specific structure and technical effects of the present invention in conjunction with the embodiments and drawings to fully understand the purpose, scheme and effects of the present invention.

[0036] Example 1

[0037] A nanocatalyst for decomposing hydrazine hydrate to produce hydrogen, the preparation method of which specifically comprises the following steps:

[0038] Step 1: Ti3C2T x Preparation: 2.0 g of lithium fluoride was added to 40 mL of 9.0 M hydrochloric acid solution for pretreatment for 15 min to completely dissolve and disperse it evenly. Then, 2.0 g of titanium aluminum carbide was added and stirred at 40°C for 48 hours. After stirring, the mixture was centrifuged and washed with deionized water several times until neutral, and finally dried in a vacuum oven to obtain a black powder.

[0039] Step 2, NiPt / (Li + )-Ti3C2T x Preparation of nanocatalyst: 30 mg of the black powder obtained in step 1 was dispersed in 5 mL of deionized water, 5 mmol of anhydrous lithium chloride was added, and the mixture was ultrasonicated for 30 min, followed by centrifugation at 5000 rpm for 10 min. The product obtained by centrifugation was then dispersed again in 5 mL of deionized water, 0.03 mmol of nickel chloride and 0.02 mmol of potassium tetrachloroplatinate were added, and the mixture was ultrasonicated at room temperature for 30 min to obtain a uniform mixture. Finally, 25 mg of sodium borohydride was added for reduction until no bubbles were generated, thereby obtaining NiPt / (Li-Pt) nanoparticles for hydrogen production from hydrazine hydrate decomposition with Ni and Pt loadings of 4.9 wt% and 10.9 wt%, respectively. + )-Ti3C2T x Nanocatalyst.

[0040] Example 2

[0041] The metal molar ratio of Ni and Pt in step 2 of Example 1 was adjusted to 10:0, and the other steps were the same as in Example 1 to obtain Ni / (Li + )-Ti3C2T x Nanocatalyst.

[0042] Example 3

[0043] The metal molar ratio of Ni and Pt in step 2 of Example 1 was adjusted to 8:2, and the other steps were the same as in Example 1 to obtain Ni 0.8 Pt 0.2 / (Li + )-Ti3C2T x Nanocatalyst.

[0044] Example 4

[0045] The metal molar ratio of Ni and Pt in step 2 of Example 1 was adjusted to 4:6, and the other steps were the same as in Example 1 to obtain Ni 0.4 Pt 0.6 / (Li + )-Ti3C2T x Nanocatalyst.

[0046] Example 5

[0047] The metal molar ratio of Ni and Pt in step 2 of Example 1 was adjusted to 2:8, and the other steps were the same as in Example 1 to obtain Ni 0.2 Pt 0.8 / (Li +) -Ti3C2T x Nanocatalyst.

[0048] Example 6

[0049] The metal molar ratio of Ni and Pt in step 2 of Example 1 was adjusted to 0:10, and the other steps were the same as in Example 1 to obtain Pt / (Li+)-Ti3C2T x Nanocatalyst.

[0050] Example 7

[0051] The Ti3C2T x The amount of Ni was adjusted to 10 mg, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0052] Example 8

[0053] The Ti3C2T x The amount of NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0054] Example 9

[0055] The Ti3C2T x The amount of Ni was adjusted to 40 mg, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0056] Example 10

[0057] The nickel salt precursor nickel chloride in step 2 of Example 1 was changed to nickel nitrate, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0058] Example 11

[0059] The nickel salt precursor nickel chloride in step 2 of Example 1 was changed to nickel sulfate, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0060] Example 12

[0061] The precursor platinum salt potassium tetrachloroplatinate in step 2 of Example 1 was replaced with platinum tetrachloride, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0062] Example 13

[0063] The precursor platinum salt potassium tetrachloroplatinate in step 2 of Example 1 was changed to hexachloroplatinic acid, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0064] Example 14

[0065] The amount of lithium chloride in step 2 of Example 1 was adjusted to 1 mmol, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0066] Example 15

[0067] The amount of lithium chloride in step 2 of Example 1 was adjusted to 2.5 mmol, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2Tx Nanocatalyst.

[0068] Example 16

[0069] The amount of lithium chloride in step 2 of Example 1 was adjusted to 10 mmol, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0070] Example 17

[0071] The amount of lithium chloride in step 2 of Example 1 was adjusted to 15 mmol, and the other steps were the same as in Example 1 to obtain NiPt / (Li + )-Ti3C2T x Nanocatalyst.

[0072] Example 18

[0073] Ni prepared by Examples 1, 2, 3, 4, 5, and 6 of the present invention y Pt 1-y / (Li + )-Ti3C2T x The nanocatalyst (wherein the ratio of y to 1-y is the molar ratio of Ni to Pt, and the value of y is 0-1) catalyzes the decomposition of hydrazine hydrate to produce hydrogen. NaOH (15 mmol) is added to the catalyst system, and 100 uL (2.0 mmol) of hydrazine hydrate is added at 323 K and normal pressure to react. The hydrogen production performance is as follows: Figure 8 The conditions for preparing the catalysts of Examples 1-6 and the results of the catalytic reactions are shown in Table 1.

[0074] Table 1 Ni prepared in Examples 1 to 6 y Pt 1-y / (Li + )-Ti3C2T x Table of performance of hydrazine hydrate production by nanocatalysts

[0075]

[0076]

[0077] The results in Table 1 show that Ni y Pt 1-y / (Li + )-Ti3C2T xAll the nanocatalysts except the one with a molar ratio of Ni to Pt of 0:10 showed 100% H2 selectivity in catalyzing hydrazine hydrate to produce hydrogen. The catalytic reaction rate of the catalyst first increased and then decreased with the increase of the molar ratio of Ni to Pt. When the molar ratio of Ni to Pt was 6:4, the nanocatalyst showed the best performance in the decomposition of hydrazine hydrate to produce hydrogen. This shows that there is a strong synergistic effect between Ni and Pt. The electronic structure of the catalysts prepared with different molar ratios of Ni and Pt is also different, which makes the final Ni y Pt 1-y / (Li + )-Ti3C2T x Nanocatalysts have different catalytic properties in reactions.

[0078] Example 19

[0079] The NiPt / (Li + )-Ti3C2T x The nanocatalyst catalyzes the decomposition of hydrazine hydrate to produce hydrogen. The catalyst is placed in a 50mL flask containing 5mL of deionized water. 100uL (2.0mmol) of hydrazine hydrate is added at 323K and atmospheric pressure to react. The hydrogen production performance is shown in the figure below. Figure 9 The conditions for catalyst preparation and the results of the catalytic reaction are shown in Table 2.

[0080] Table 2 NiPt / (Li prepared in Examples 1 and 7-9 + )-Ti3C2T x Table of performance of hydrazine hydrate production by nanocatalysts

[0081]

[0082] The results in Table 2 show that NiPt / (Li + )-Ti3C2T x The selectivity and activity of nanocatalysts for hydrogen production from hydrazine hydrate increased with the increase of Ti3C2T x The catalyst's selectivity and activity initially increased with increasing carrier dosage, then decreased. When the carrier dosage was very low, the catalyst's selectivity and activity were both relatively low. This was primarily due to the low carrier dosage leading to an excessively high active metal loading, preventing the metal nanoparticles from dispersing, resulting in poor catalytic performance. However, when the carrier dosage was increased to 30 mg, the catalyst achieved optimal catalytic activity. Further increases in the carrier dosage resulted in a slight decrease in catalytic activity. This suggests that the catalyst can effectively disperse metal nanoparticles and enhance catalytic activity. However, excessive carrier dosage prevents the active metal from readily contacting hydrazine hydrate, resulting in a decrease in performance.

[0083] Example 20

[0084] NiPt / (Li + )-Ti3C2T x The nanocatalyst catalyzes the decomposition of hydrazine hydrate to produce hydrogen. NaOH (15 mmol) is added to the catalyst system, and 100 uL (2.0 mmol) of hydrazine hydrate is added at 323K and normal pressure to react. The hydrogen production performance is shown in the figure below. Figure 10 The conditions for catalyst preparation and the results of the catalytic reaction are shown in Table 3.

[0085] Table 3 NiPt / (Li prepared in Examples 1 and 14-17 + )-Ti3C2T x Table of performance of hydrazine hydrate production by nanocatalysts

[0086]

[0087] The results in Table 3 show that NiPt / (Li + )-Ti3C2T x The nanocatalyst catalyzed hydrazine hydrate hydrogen production showed 100% H2 selectivity. The catalytic reaction rate showed a trend of first increasing and then decreasing with the increase of the amount of intercalation agent lithium chloride. When the dosage was 5.0 mmol, NiPt / (Li + )-Ti3C2T x Nanocatalysts showed the best performance in hydrogen production from hydrazine hydrate decomposition. This is mainly attributed to the fact that lithium chloride intercalation treatment can make Ti3C2T x Exposing more surface functional groups enhances its adsorption capacity for metal precursor salt ions, effectively reduces the size of metal nanoparticles, and optimizes the electronic structure of the catalyst, thereby effectively improving the catalytic reaction activity. However, when the amount of lithium chloride is too much, it will destroy the Ti3C2T x The structure is not conducive to the reduction and dispersion of nanoparticle size, making the final NiPt / (Li + )-Ti3C2T x The catalytic performance of the nanocatalyst in the reaction decreases.

[0088] Example 21

[0089] The NiPt / (Li + )-Ti3C2T x The nanocatalyst catalyzes the decomposition of hydrazine hydrate to produce hydrogen at different temperatures. The catalyst was placed in a 50 mL flask containing 5 mL of deionized water. 100 uL (2.0 mmol) of hydrazine hydrate was added at 303 K, 313 K, 323 K, and 333 K under normal pressure to react. The hydrogen production performance is shown in the figure below. Figure 12The conditions for catalyst preparation and the results of the catalytic reaction are shown in Table 6.

[0090] Table 6 NiPt / (Li prepared in Example 1 + )-Ti3C2T x Table of performance of nanocatalysts in catalytic hydrazine hydrate hydrogen production at different catalytic temperatures

[0091]

[0092] The results in Table 6 show that NiPt / (Li + )-Ti3C2T x The nanocatalyst catalyzed hydrazine hydrate hydrogen production showed 100% H2 selectivity, and the catalytic reaction rate and reaction activity were significantly improved with the increase of temperature. This is mainly attributed to the fact that high temperature can activate the catalyst and thus effectively improve the catalytic reaction activity. It can also be seen that at 323K, the prepared NiPt / (Li + )-Ti3C2T x The nanocatalyst catalyzes the complete decomposition and dehydrogenation of hydrazine hydrate in just 1.5 minutes, with a turnover frequency (TOF) value of up to 3200 h -1 , which is higher than all reported hydrazine hydrate decomposition hydrogen production catalysts.

[0093] Example 22

[0094] The NiPt / (Li + )-Ti3C2T x The nanocatalyst catalyzes the decomposition of hydrazine hydrate to produce hydrogen. The catalyst is placed in a 50 mL flask containing 5 mL of deionized water. 100 uL (2.0 mmol) of hydrazine hydrate is added at 323 K and atmospheric pressure to react for 5 cycles. The hydrogen production performance is shown in the figure below. Figure 12 As shown. Figure 12 It can be seen that the NiPt / (Li+)-Ti3C2Tx nanocatalyst has good cyclic stability for the decomposition of hydrazine hydrate to produce hydrogen. The catalyst activity and gas production do not decrease after repeated use for 5 times, indicating that the catalyst has good catalytic activity and cyclic stability.

[0095] from Figure 1 It can be seen that as the ratio of Ni and Pt metals decreases, the metal peak intensity of the catalyst gradually increases and the metal peak shifts to the characteristic peak position of Pt.

[0096] from Figure 2 It can be seen that after lithium ion intercalation treatment (Li + )-Ti3C2T xCompared with the one before intercalation treatment, there is a stronger infrared absorption peak of the functional group, indicating that lithium ion intercalation treatment can expose more surface functional groups on the carrier.

[0097] from Figure 3 It can be seen that lithium ion intercalation treatment and metal loading do not have a significant effect on the molecular structure of the carrier.

[0098] from Figure 4 It can be seen that after lithium ion intercalation treatment, the specific surface area of ​​the carrier is increased from the initial 9.97m 2 / g increased to 13.82m 2 / g, indicating that lithium ion intercalation treatment can effectively increase the interlayer spacing and thus improve the specific surface area.

[0099] from Figure 5 It can be seen from the figure that the catalyst sample has an obvious lamellar structure, and ultrafine NiPt alloy nanoparticles with a particle size of 1.8±0.2nm are uniformly dispersed on the carrier.

[0100] from Figure 6 It can be seen that the catalyst contains Ni, Pt, Ti, C, and O elements.

[0101] from Figure 7 It can be found that the elemental composition of all catalysts is mainly Ni, Pt, Ti, C, and O.

[0102] NiPt / (Li + )-Ti3C2T x The excellent activity of the nanocatalyst is attributed to the enhanced performance of Ti3C2T by lithium ion intercalation treatment. x The number of surface functional groups enables the carrier to effectively adsorb metal precursor salt ions, and the ultrafine NiPt metal nanoparticles are loaded on the two-dimensional Ti3C2T treated with lithium ion intercalation. x In addition, lithium ion intercalation can effectively enhance the electron transfer between catalysts, forming a catalyst with stronger electronic effect.

[0103] In summary, the method for preparing the catalyst of the present invention is simple to operate and pollution-free. The obtained catalyst has the characteristics of small particle size, multiple catalytic active sites, and high catalytic activity and stability, and is a catalyst with great development prospects.

[0104] Obviously, the described embodiments are only some of the embodiments of the present application, rather than all of the embodiments. Mentioning "embodiments" in this article means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present embodiment application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It can be understood explicitly and implicitly by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application. Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and purpose of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A nanocatalyst for decomposing hydrazine hydrate to produce hydrogen, characterized in that: The nanocatalyst consists of NiPt nanoparticles uniformly dispersed in Li + Intercalated two-dimensional layered Ti3C2T x The chemical formula of the nanocatalyst is NiPt / (Li + )-Ti3C2T x ; The preparation method of the nanocatalyst comprises the following steps: First, Ti3C2T x The powder is dispersed in water, lithium chloride is added for ultrasonic intercalation treatment, and then centrifuged and layered to obtain an intermediate product; the intermediate product is then dispersed in water, nickel source precursor and platinum source precursor are added, and ultrasonic treatment is carried out at room temperature. After the ultrasonic treatment, sodium borohydride is added for reduction reaction until no bubbles are generated, and finally NiPt / (Li + )-Ti3C2T x Nanocatalysts; Ti3C2T x , lithium chloride and sodium borohydride in a ratio of 30 mg:5 mmol:25 mg; The average particle size of NiPt nanoparticles is 1.8 nm ± 0.2 nm.

2. The nanocatalyst according to claim 1, characterized in that The content of Ni in the nanocatalyst is greater than 0 and less than 8.9 wt %, and the content of Pt is greater than 0 and less than 24.5 wt %.

3. The nanocatalyst according to claim 2, characterized in that The molar ratio of Ni to Pt in the nanocatalyst is 6:

4.

4. The nanocatalyst according to claim 1, characterized in that Ti3C2T x It is obtained by the following steps: Lithium fluoride was dispersed in 9.0 M hydrochloric acid solution and then titanium aluminum carbide was added and stirred at 40 °C for 48 hours. After stirring, it was washed with water until neutral and vacuum dried to obtain Ti3C2T x .

5. Use of the nanocatalyst according to any one of claims 1 to 4 in the preparation of a hydrogen source for a fuel cell.

6. The use of the nanocatalyst according to claim 5 in the preparation of hydrogen source for fuel cells, characterized in that: Nanocatalysts are used to catalyze the decomposition of hydrazine hydrate to produce hydrogen at a temperature of 303 K to 333 K.

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