Bimetal composite catalyst for hydrolysis hydrogen production as well as preparation method and application of bimetal composite catalyst

Abstract

The invention relates to a bimetallic composite catalyst for hydrolysis hydrogen production and preparation and application thereof, the MXene catalyst comprises a two-dimensional layered structure Ti3C2Tx and copper formed on the surface in situ, and Tx is Cl <-> or O < 2->. Compared with the prior art, the preparation method provided by the invention has the advantages that the raw materials are easy to obtain, the price is relatively low, the preparation method is simple, the dangerousness is relatively low, the test period is short, the MXene etching dangerousness and the impurity removal difficulty are favorably reduced by utilizing the molten salt method for preparation, and the synthesized Ti3C2Tx not only has the excellent characteristics of two-dimensional layered structure Ti3C2, but also has the advantages of simple preparation process and low cost. And meanwhile, the copper-based composite material has excellent catalytic performance of copper, and can be widely applied to the fields of catalysts, hydrolysis hydrogen production materials, hydrogen storage materials, battery materials, supercapacitors, photoelectric materials and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen storage materials and relates to a bimetallic composite catalyst for producing hydrogen by hydrolysis and a preparation method thereof. Background Art

[0002] The hydrolysis reaction of magnesium hydride (MgH2) and water requires relatively low reaction conditions and simple reaction equipment. However, the Mg(OH)2 generated by the reaction will deposit on the surface of MgH2 to form a dense passivation layer that prevents the internal MgH2 from contacting with water molecules, resulting in poor hydrolysis performance of MgH2.

[0003] Commonly used MgH2 hydrolysis modification methods include adjusting solution composition, introducing additives through mechanical ball milling, and alloying. Recent studies have shown that the addition of metal catalysts can significantly improve the hydrolysis performance of magnesium hydride-based hydrogen storage materials. The mechanism of action is as follows: the metal catalyst adheres to the surface of the MgH2 material, preventing the surface material from agglomerating and the formation of a surface passivation layer. At the same time, it acts as a channel to promote the diffusion of hydrogen molecules and the contact of water molecules with the material surface until the hydrolysis reaction is completed. A related report (A highly efficient hydrolysis of MgH2 catalyzed by NiCo@C bimetallicsynergistic effect, Journal of Materials Science & Technology, 137 (2023) 176-183) used cobalt nitrate hexahydrate and nickel nitrate hexahydrate as cobalt and nickel sources, and 2-methylimidazole as a carbon source to prepare a carbon-supported nickel-cobalt bimetallic catalyst. The carbon-supported nickel-cobalt bimetallic catalyst was introduced into MgH2 by ball milling, and magnesium chloride solution was used to achieve complete hydrolysis within 15 min, with a hydrogen production of up to 1702.2 mL g -1 The conversion rate is close to 100%, which maximizes the high theoretical hydrogen production of MgH2.

[0004] In recent years, the two-dimensional layered structure material MXene has been used in the fields of batteries and hydrogen storage due to its good conductivity, large interlayer gap, relatively stable structure and strong load capacity.

[0005] For example, Chinese patent application CN202111281676.9 discloses a three-dimensional structured MXene / SnO2 / C negative electrode composite material and a preparation method thereof, wherein the three-dimensional structured MXene / SnO2 / C negative electrode composite material uniformly mixes MXene with a metal organic framework coated with SnO2 nanoparticles, wherein the SnO2 nanoparticles are coated on the surface of the metal organic framework to form a core-shell structure, wherein the transition metal in the MXene is one or more of Ti, V, and Nb. However, this type of catalyst not only uses concentrated hydrochloric acid as an etchant in MAX phase etching, but also uses dimethylimidazole and methanol in the preparation of the metal organic framework, and also uses sodium borohydride as a reducing agent when forming a core-shell structure. The entire preparation process is cumbersome and dangerous drugs are frequently used, which creates considerable difficulty for the successful preparation of the catalyst. Summary of the invention

[0006] The purpose of the present invention is to provide a bimetallic composite catalyst for hydrogen production by hydrolysis and its preparation and application. The obtained catalyst has good catalytic performance and can be applied to the fields of catalyst, hydrogen production by hydrolysis material, hydrogen storage material, battery material and supercapacitor, and has good performance. In addition, the method is simple in process and the obtained product has high purity, good dispersibility of each component and good catalytic performance.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] In one aspect, the present invention provides a MXene catalyst for hydrogen production by water splitting, which comprises a two-dimensional layered structure Ti3C2T x , and copper formed in situ on the surface, where T x Including Cl - , O 2- .

[0009] Furthermore, in the MXene catalyst, the two-dimensional layered structure Ti3C2T x The mass percentage of isocyanate is 90-95%, preferably about 92.4%, and the mass percentage of copper is 5-10%, preferably about 7.6%.

[0010] On the other hand, the present invention also provides a method for preparing a MXene catalyst for hydrolysis hydrogen production, comprising the following steps:

[0011] (1) mixing titanium carbide aluminum, copper chloride, sodium chloride and potassium chloride uniformly and subjecting them to high temperature heat treatment in an inert gas atmosphere;

[0012] (2) The product obtained in step (1) is washed, desalted and then dried to obtain the MXene catalyst.

[0013] Since the temperature during high temperature treatment is 700℃, Al will combine with Cl to generate AlCl3 gas and be discharged. Sodium salt and potassium salt can be easily removed by adding pure water and centrifugation due to their water-soluble properties.

[0014] Furthermore, in step (1), the molar ratio of titanium aluminum carbide, copper chloride, sodium chloride and potassium chloride is 1:(2-4):(1.5-2.5):(1.5-2.5). Preferably, the molar ratio is 1:3:2:2.

[0015] Furthermore, the chloride salts such as copper chloride, sodium chloride, potassium chloride, etc. used in the preparation process of the present invention are preferably anhydrous chlorides. In molten salt etching, the hydrogen bonds in the hydrated salts will affect the etching effect on the MAX phase.

[0016] Furthermore, in step (1), the temperature of the high temperature heat treatment is 600-800°C, and illustratively, the temperature can be 600°C, 700°C, or 800°C, and the time is 5-9h, and illustratively, it can be 5h, 7h, or 9h.

[0017] Furthermore, in step (1), the inert gas atmosphere is argon.

[0018] Furthermore, the cleaning process is specifically as follows: deionized water is used for cleaning and desalting, and the mixture is centrifuged twice at a speed of 10,000 r / min for 5 minutes.

[0019] Furthermore, the drying method may be freeze drying.

[0020] In a third aspect, the present invention further provides a magnesium hydride-based hydrolysis hydrogen production material, which comprises, by mass percentage, 93-99% magnesium hydride and 1-7% of the MXene catalyst for hydrolysis hydrogen production as described above.

[0021] Furthermore, the particle size of the magnesium hydride powder is less than 40 μm.

[0022] Furthermore, the magnesium hydride and the MXene catalyst for producing hydrogen by hydrolysis are both in powder form. In addition, specifically, the purity of the magnesium hydride powder is above 99%.

[0023] In a fourth aspect, the present invention provides a method for preparing a magnesium hydride-based hydrolysis hydrogen production material, comprising weighing magnesium hydride and a MXene catalyst for hydrolysis hydrogen production according to a ratio, mixing, and ball milling to obtain the magnesium hydride-based hydrolysis hydrogen production material.

[0024] Furthermore, the ball milling mixing is carried out under the protection of an inert atmosphere, preferably an argon atmosphere, the ball milling time is 20 min-7 h, preferably 20 min-80 min, and exemplarily 60 min, the ball-to-material ratio is 35-45:1, preferably 40:1, and the rotation speed is 300-500 r / min, and exemplarily 400 r / min.

[0025] For the MXene catalyst for hydrogen production by hydrolysis of the present invention, Ti3C2T x The electronic interaction of Cu atoms on the surface can reduce the binding energy of protons on the active sites, thus enhancing the kinetics of H2 evolution. x The two interact with each other, and at the same time show a synergistic effect of accelerating charge transfer and increasing the reactive sites on the MgH2 surface. The two together form a channel on the MgH2 surface that promotes the rapid diffusion of H atoms, which is not only conducive to the continuous escape of H2 bubbles, but also hinders the formation of a continuous Mg(OH)2 passivation layer, so that Mg(OH)2 can only exist in the solution in the form of fragments, thereby promoting the continuous hydrolysis and hydrogen release of MgH2 until the reaction is complete, thereby showing excellent hydrolysis and hydrogen production performance.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The raw materials for the preparation method provided by the present invention are easily available and relatively inexpensive.

[0028] (2) The preparation method provided by the present invention is relatively simple, less dangerous, and has a short experimental period. The molten salt method used in the present invention is conducive to reducing the danger of MXene etching and the difficulty of impurity removal.

[0029] (3) The MXene catalyst prepared in the present invention contains an in-situ generated metal particle, namely, copper particles, on the Ti3C2T x The surface dispersibility is good and the particle size is small. The present invention utilizes the oxidizing property of Lewis acid under high temperature conditions to etch the Al in MAX and retain the reduced metal element Cu on the surface of MXene.

[0030] (4) Ti3C2T synthesized by the present invention x (i.e. MXene catalyst for hydrogen production by hydrolysis) not only has the excellent properties of the two-dimensional layered structure Ti3C2, but also has the excellent catalytic properties of copper. It can be widely used in many fields such as catalysts, hydrogen production materials by hydrolysis, hydrogen storage materials, battery materials, supercapacitors and optoelectronic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the FESEM image of the MXene catalyst of Example 1 of the present invention.

[0032] Figure 2 This is the XRD diagram of the hydrolysis product obtained by the reaction of magnesium hydride and MXene catalyst in Example 1 of the present invention.

[0033] Figure 3 The hydrolysis curves of magnesium hydride and MXene catalysts in different proportions (1-7 wt%) of Example 1 and Example 2 of the present invention after ball milling for 1 hour.

[0034] Figure 4 This is the EDS energy spectrum of the MXene catalyst of Example 1 of the present invention.

[0035] Figure 5 This is a hydrolysis curve diagram of magnesium hydride and MXene catalyst in Example 3 of the present invention after ball milling for different times (20-80 min).

[0036] Figure 6 This is a hydrolysis curve of pure magnesium hydride after ball milling in Comparative Example 1 of the present invention.

[0037] Figure 7 This is a hydrolysis curve of the MXene-Co catalyst of Comparative Example 2 of the present invention when magnesium hydride is added.

[0038] Figure 8 This is a hydrolysis curve of the MXene catalyst for removing Cu in Comparative Example 3 of the present invention when magnesium hydride is added. DETAILED DESCRIPTION

[0039] 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.

[0040] The various reagents and raw materials used in the following examples are all commercially available products. The purity of the titanium aluminum carbide is ≥99.9%, and the anhydrous copper chloride, anhydrous sodium chloride and anhydrous potassium chloride are of analytical grade.

[0041] Example 1

[0042] A MXene catalyst for hydrogen production by hydrolysis (i.e., a bimetallic composite catalyst for hydrogen production by hydrolysis), wherein the mass percentage of the MXene catalyst is about 92.4%, the mass percentage of the copper is 7.6%, and the catalyst is prepared by the following method:

[0043] Titanium aluminum carbide, copper chloride, sodium chloride, and potassium chloride were mixed evenly at a molar ratio of 1:3:2:2 and placed in an alumina crucible. The alumina crucible was placed in a tube furnace and heat treated at 700°C for 7 hours under an argon atmosphere. The sample prepared above was added to deionized water for washing and desalting, centrifuged, and freeze-dried to obtain the MXene catalyst.

[0044] The catalytic performance of the prepared MXene catalyst was tested: 0.95 g of magnesium hydride powder and 0.05 g of MXene powder material were put into a ball mill, wherein the ball milling process was carried out under the protection of an argon atmosphere, the ball milling time was 1 h, the ball-to-material ratio (i.e., the ratio of the mass of the steel ball to the total mass of the mixed hydrolysis hydrogen production sample) was 40:1, the rotation speed was 400 r / min, and magnesium hydride / MXene powder was obtained, thereby obtaining a magnesium hydride-based hydrolysis hydrogen production material.

[0045] The present invention adopts the water displacement substitution method to determine the hydrolysis performance of the MgH2-based composite material. An electronic balance is used to measure the mass of water replaced by the escaped hydrogen, and the balance reading is the volume of hydrogen produced by hydrolysis. The volume of H2 produced by hydrolysis is equal to the balance reading. The electronic balance is connected to a computer, and the computer can automatically record data and reaction time. In this experiment, the hydrogen yield of the entire sample is calculated by hydrolyzing 0.1g of the composite sample, and then converted into the hydrogen yield under standard conditions by the ideal gas equation.

[0046] The magnesium hydride-based hydrolysis hydrogen production material prepared using the MXene catalyst provided in this embodiment has a final hydrogen release rate of 1767.03 mL g in 30 min in a 0.05 mol / L MgCl2 solution with a 5% MXene catalyst. -1 , the hydrogen release efficiency is 93.6%.

[0047] Figure 1 and Figure 4 These are the FESEM and EDS spectra of the MXene material prepared in Example 1. From the figures, we can see the Ti3C2 layered structure and the copper particles evenly distributed on the surface. Figure 3 This is the hydrolysis curve of magnesium hydride and MXene material prepared in Example 1. From the figure, it can be seen that the final hydrogen release amount of magnesium hydride and 5% MXene material within 30 minutes is 1789.31mLg -1 , the hydrogen decomposition efficiency is 95.63%, indicating that the catalyst greatly improves the hydrogen production performance of magnesium hydride by hydrolysis.

[0048] It can be seen that the catalyst performance of this embodiment is good, partly because MXene and magnesium hydride powder play a role as a grinding aid during ball milling, which helps to refine magnesium hydride particles. In addition, the high entropy alloy powder is evenly dispersed on the surface of magnesium hydride after ball milling, and is well combined with it, providing a diffusion channel for hydrogen while effectively preventing magnesium hydride particles from agglomerating, hindering the formation of a continuous Mg(OH)2 passivation layer, so that Mg(OH)2 exists in a fragmented state, which helps to improve the hydrolysis performance of magnesium hydride.

[0049] Figure 2 This is the XRD diagram of the hydrolysis product obtained by the reaction of magnesium hydride and MXene catalyst in Example 1 of the present invention. It can be seen from the figure that the main components of the composite material after hydrolysis are Mg(OH)2 and Cu, indicating that the degree of hydrolysis is relatively complete.

[0050] Example 2

[0051] A MXene catalyst for hydrogen production by hydrolysis (i.e., a bimetallic composite catalyst for hydrogen production by hydrolysis), wherein the mass percentage of the MXene catalyst is about 92.4%, the mass percentage of the copper is 7.6%, and the catalyst is prepared by the following method:

[0052] Titanium aluminum carbide, copper chloride, sodium chloride, and potassium chloride were mixed evenly at a molar ratio of 1:3:2:2 and placed in an alumina crucible. The alumina crucible was placed in a tube furnace and heat treated at 700°C for 7 hours under an argon atmosphere. The sample prepared above was added to deionized water for washing and desalting, centrifuged, and freeze-dried to obtain the MXene catalyst.

[0053] The catalytic performance of the prepared MXene catalyst was tested: 0.93 g of magnesium hydride powder and 0.07 g of MXene powder material were put into a ball mill, wherein the ball milling process was carried out under the protection of an argon atmosphere, the ball milling time was 1 h, the ball-to-material ratio (i.e., the ratio of the mass of the steel ball to the total mass of the mixed hydrolysis hydrogen production sample) was 40:1, the rotation speed was 400 r / min, and magnesium hydride / MXene powder was obtained, thereby obtaining a magnesium hydride-based hydrolysis hydrogen production material.

[0054] The present invention adopts the water displacement substitution method to determine the hydrolysis performance of the MgH2-based composite material. An electronic balance is used to measure the mass of water replaced by the escaped hydrogen, and the balance reading is the volume of hydrogen produced by hydrolysis. The volume of H2 produced by hydrolysis is equal to the balance reading. The electronic balance is connected to a computer, and the computer can automatically record data and reaction time. In this experiment, the hydrogen yield of the entire sample is calculated by hydrolyzing 0.1g of the composite sample, and then converted into the hydrogen yield under standard conditions by the ideal gas equation.

[0055] The magnesium hydride-based hydrolysis hydrogen production material prepared using the MXene catalyst provided in this embodiment has a hydrolysis hydrogen production curve of 7% MXene catalyst in 0.05 mol / L MgCl2 solution at 30°C. Figure 2 .

[0056] from Figure 3 It can be seen that the final hydrogen release amount within 30 min is 1725.27 mL g -1 The hydrogen decomposition efficiency is 92.21%, indicating that the catalyst improves the hydrogen production performance of magnesium hydride by hydrolysis, but compared with the catalyst dosage of 5% MXene, the final hydrogen production amount is reduced.

[0057] Example 3

[0058] A MXene catalyst for hydrogen production by hydrolysis (i.e., a bimetallic composite catalyst for hydrogen production by hydrolysis), wherein the mass percentage of the MXene catalyst is about 92.4%, the mass percentage of the copper is 7.6%, and the catalyst is prepared by the following method:

[0059] Titanium aluminum carbide, copper chloride, sodium chloride, and potassium chloride were mixed evenly at a molar ratio of 1:3:2:2 and placed in an alumina crucible. The alumina crucible was placed in a tube furnace and heat treated at 700°C for 7 hours under an argon atmosphere. The sample prepared above was added to deionized water for washing and desalting, centrifuged, and freeze-dried to obtain the MXene catalyst.

[0060] The catalytic performance of the prepared MXene catalyst was tested: 0.97 g of magnesium hydride powder and 0.03 g of MXene powder material were put into a ball mill, wherein the ball milling process was carried out under the protection of an argon atmosphere, the ball milling time was 1 h, the ball-to-material ratio (i.e., the ratio of the mass of the steel ball to the total mass of the mixed hydrolysis hydrogen production sample) was 40:1, the rotation speed was 400 r / min, and magnesium hydride / MXene powder was obtained, thereby obtaining a magnesium hydride-based hydrolysis hydrogen production material.

[0061] The present invention adopts the water displacement substitution method to determine the hydrolysis performance of the MgH2-based composite material. An electronic balance is used to measure the mass of water replaced by the escaped hydrogen, and the balance reading is the volume of hydrogen produced by hydrolysis. The volume of H2 produced by hydrolysis is equal to the balance reading. The electronic balance is connected to a computer, and the computer can automatically record data and reaction time. In this experiment, the hydrogen yield of the entire sample is calculated by hydrolyzing 0.1g of the composite sample, and then converted into the hydrogen yield under standard conditions by the ideal gas equation.

[0062] The magnesium hydride-based hydrolysis hydrogen production material prepared using the MXene catalyst provided in this embodiment has a hydrolysis hydrogen production curve of 3% MXene catalyst in 0.05 mol / L MgCl2 solution at 30°C. Figure 3 .

[0063] From the figure, we can see that the final hydrogen release within 30 min is 1745.28 mL g -1 The hydrogen decomposition efficiency is 93.28%, indicating that the catalyst improves the hydrogen production performance of magnesium hydride by hydrolysis, but the amount of hydrogen produced is reduced compared to the catalyst dosage of 5% MXene.

[0064] Example 4

[0065] A MXene catalyst for hydrogen production by hydrolysis (i.e., a bimetallic composite catalyst for hydrogen production by hydrolysis), wherein the mass percentage of the MXene catalyst is about 92.4%, the mass percentage of the copper is 7.6%, and the catalyst is prepared by the following method:

[0066] Titanium aluminum carbide, copper chloride, sodium chloride, and potassium chloride were mixed evenly at a molar ratio of 1:3:2:2 and placed in an alumina crucible. The alumina crucible was placed in a tube furnace and heat treated at 700°C for 7 hours under an argon atmosphere. The sample prepared above was added to deionized water for washing and desalting, centrifuged, and freeze-dried to obtain the MXene catalyst.

[0067] The catalytic performance of the prepared MXene catalyst was tested: 0.95 g of magnesium hydride powder and 0.05 g of MXene catalyst material were put into a ball mill, wherein the ball milling process was carried out under the protection of an argon atmosphere, the ball milling time was 40 min, the ball-to-material ratio (i.e., the ratio of the mass of the steel ball to the total mass of the mixed hydrolysis hydrogen production sample) was 40:1, the rotation speed was 400 r / min, and magnesium hydride / MXene powder was obtained, thereby obtaining a magnesium hydride-based hydrolysis hydrogen production material.

[0068] After 40 min of ball milling, the hydrolysis hydrogen production curve of 5% MXene catalyst in 0.05 mol / L MgCl2 solution at 30 °C is shown in Figure 2. Figure 5 As can be seen from the figure, the final hydrogen release amount within 40 min is 1770.54 mL g -1 The hydrogen decomposition efficiency is 94.63%. Compared with the ball milling time of 60 min, the amount of hydrogen produced is slightly reduced, and the hydrogen production rate is also reduced.

[0069] Example 5

[0070] A MXene catalyst for hydrogen production by hydrolysis (i.e., a bimetallic composite catalyst for hydrogen production by hydrolysis), wherein the mass percentage of the MXene catalyst is about 92.4%, the mass percentage of the copper is 7.6%, and the catalyst is prepared by the following method:

[0071] Titanium aluminum carbide, copper chloride, sodium chloride, and potassium chloride were mixed evenly at a molar ratio of 1:3:2:2 and placed in an alumina crucible. The alumina crucible was placed in a tube furnace and heat treated at 700°C for 7 hours under an argon atmosphere. The sample prepared above was added to deionized water for washing and desalting, centrifuged, and freeze-dried to obtain the MXene catalyst.

[0072] The catalytic performance of the prepared MXene catalyst was tested: 0.95 g of magnesium hydride powder and 0.05 g of MXene catalyst material were put into a ball mill, wherein the ball milling process was carried out under the protection of an argon atmosphere, the ball milling time was 20 min, the ball-to-material ratio (i.e., the ratio of the mass of the steel ball to the total mass of the mixed hydrolysis hydrogen production sample) was 40:1, the rotation speed was 400 r / min, and magnesium hydride / MXene powder was obtained, thereby obtaining a magnesium hydride-based hydrolysis hydrogen production material.

[0073] After 80 min of ball milling, the hydrolysis hydrogen production curve of 5% MXene catalyst in 0.05 mol / L MgCl2 solution at 30 °C is shown in Figure 2. Figure 5 As can be seen from the figure, the final hydrogen release amount within 80 min is 1749.24 mL g -1 The hydrogen desorption efficiency is 93.49%. Compared with the ball milling time of 60 min, the amount of hydrogen produced is slightly reduced, and the hydrogen production rate is also reduced.

[0074] It can be seen from Examples 4 and 5 that 60 min is the relatively optimal ball milling time in this experiment, which can achieve the best kinetic performance of the hydrolysis of the composite, not only with a faster speed but also with the maximum final hydrogen production.

[0075] Comparative Example 1

[0076] 1g of magnesium hydride powder was put into a ball mill, wherein the ball milling process was carried out under the protection of argon atmosphere, the ball milling time was 1h, the ball-to-material ratio (i.e., the ratio of the mass of the steel ball to the total mass of the mixed hydrolysis hydrogen production sample) was 40:1, the rotation speed was 400r / min, and magnesium hydride powder was obtained, and magnesium hydride-based hydrolysis hydrogen production material was obtained. The above material was hydrolyzed in a 0.05mol / L MgCl2 solution at 30°C.

[0077] from Figure 6 It can be seen that at 30°C, the final hydrogen release amount of pure magnesium hydride ball-milled for 1 hour within 60 minutes is 1632.2 mL g-1, and the hydrogen release efficiency is 86.45%.

[0078] The difference between Example 1 and Comparative Example 1 is that Example 1 uses a mixture of magnesium hydride and MXene catalyst to test the catalytic performance, while Comparative Example 1 uses pure magnesium hydride under the same conditions to test the catalytic performance.

[0079] In addition, regarding the composite catalyst prepared by the present invention containing copper particles, reference Figure 1 Figure 4 It can be seen from the medium-scale data and particle size that the copper particles are well dispersed on the Ti3C2 two-dimensional layered structure and have a very small particle size.

[0080] Comparative Example 2

[0081] Titanium aluminum carbide, cobalt chloride, sodium chloride, and potassium chloride were mixed evenly in a molar ratio of 1:3:2:2 and placed in an alumina crucible. The alumina crucible was placed in a tube furnace and heat treated at 700°C for 7 hours under an argon atmosphere. Due to the same principle, the reaction products are MXene, Co metal element, and chloride. The above-prepared sample was added to deionized water for washing and desalting, centrifuged, and freeze-dried to obtain a MXene-Co catalyst.

[0082] The catalytic performance of the prepared MXene-Co catalyst was tested: 0.95 g of magnesium hydride powder and 0.05 g of MXene powder material were put into a ball mill, and the ball milling process was carried out under the protection of an argon atmosphere. The ball milling time was 1 h, the ball-to-material ratio (i.e., the ratio of the mass of the steel ball to the total mass of the mixed hydrolysis hydrogen production sample) was 40:1, and the rotation speed was 400 r / min. Magnesium hydride / MXene powder was obtained, and magnesium hydride-based hydrolysis hydrogen production material was obtained.

[0083] The magnesium hydride-based hydrolysis hydrogen production material prepared using the MXene catalyst provided in this embodiment has a hydrolysis hydrogen production curve of 5% MXene-Co catalyst in 0.05 mol / L MgCl2 solution at 30°C. Figure 7 .

[0084] From the figure, we can see that the final hydrogen release within 30 min is 1726.48 mL g -1 The hydrogen release efficiency is 92.273%, indicating that the catalyst improves the performance of hydrogen production by hydrolysis of magnesium hydride, but compared with the MXene-Cu catalyst, the amount of hydrogen produced by hydrolysis produced by the addition of the catalyst is relatively small. At the same time, it can be shown that Cu has a relatively better performance in catalyzing the hydrolysis of magnesium hydride.

[0085] Comparative Example 3

[0086] The MXene catalyst prepared in Example 1 was added to a 0.1M FeCl3 solution, stirred for 4 hours, centrifuged, washed, freeze-dried, and collected for later use. Since the FeCl3 solution is oxidizing, it can undergo a redox reaction with Cu to achieve the purpose of removing Cu. After the above treatment, the performance of the obtained MXene catalyst was tested:

[0087] Take 0.95g of magnesium hydride powder and 0.05g of MXene powder material after removing Cu and put them into a ball mill, wherein the ball milling process is carried out under the protection of argon atmosphere, the ball milling time is 1h, the ball-to-material ratio (i.e., the ratio of the mass of the steel ball to the total mass of the mixed hydrolysis hydrogen production sample) is 40:1, the rotation speed is 400r / min, and magnesium hydride / MXene powder is obtained, that is, the magnesium hydride-based hydrolysis hydrogen production material is obtained.

[0088] The MgH-based hydrolysis hydrogen production material prepared by using the MXene catalyst provided in this embodiment has a hydrolysis hydrogen production curve of the MXene catalyst with 5% Cu removed in a 0.05 mol / L MgCl2 solution at 30°C. Figure 8 .

[0089] From the figure, we can see that the final hydrogen release within 30 min is 1725.8 mL g -1 The hydrogen release efficiency is 92.235%, which shows that the catalyst improves the performance of pure magnesium hydride in hydrogen production by hydrolysis. However, compared with the MXene-Cu catalyst, the performance of the catalyst after removing Cu is significantly reduced. At the same time, it can be shown that Cu has a good performance in catalyzing the hydrolysis of magnesium hydride.

[0090] 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 MXene catalyst for producing hydrogen by hydrolysis, characterized in that: It consists of a two-dimensional layered structure Ti3C2T x , and copper formed in situ on the surface, where T x Including Cl - , O 2- .

2. A MXene catalyst for producing hydrogen by hydrolysis according to claim 1, characterized in that: In the MXene catalyst, the two-dimensional layered structure Ti3C2T x The mass percentage of quartz is 90-95%, and the mass percentage of copper is 5-10%.

3. The method for preparing a MXene catalyst for producing hydrogen by hydrolysis according to claim 1 or 2, characterized in that: The steps include: (1) mixing titanium carbide aluminum, copper chloride, sodium chloride and potassium chloride uniformly and subjecting them to high temperature heat treatment in an inert gas atmosphere; (2) The product obtained in step (1) is washed, desalted and then dried to obtain the MXene catalyst.

4. The method for preparing a MXene catalyst for producing hydrogen by hydrolysis according to claim 3, characterized in that: In step (1), the molar ratio of titanium aluminum carbide, copper chloride, sodium chloride and potassium chloride is 1:(2-4):(1.5-2.5):(1.5-2.5).

5. The method for preparing a MXene catalyst for producing hydrogen by hydrolysis according to claim 3, characterized in that: In step (1), the temperature of the high temperature heat treatment is 600-800°C and the time is 5-9h.

6. The method for preparing a MXene catalyst for producing hydrogen by hydrolysis according to claim 3, characterized in that: In step (1), the inert gas atmosphere is argon.

7. A magnesium hydride-based hydrolysis hydrogen production material, characterized in that: By mass percentage, it comprises 93-99% magnesium hydride and 1-7% of the MXene catalyst for producing hydrogen by hydrolysis as claimed in claim 1 or 2.

8. The magnesium hydride-based hydrolysis hydrogen production material according to claim 7, characterized in that: The particle size of the magnesium hydride powder is less than 40 μm.

9. The method for preparing a magnesium hydride-based hydrolysis hydrogen production material according to claim 7, characterized in that: Magnesium hydride and a MXene catalyst for hydrogen production by hydrolysis are weighed and mixed according to a ratio, and ball milled to obtain the magnesium hydride-based hydrogen production material by hydrolysis.

10. The method for preparing a magnesium hydride-based hydrolysis hydrogen production material according to claim 9, characterized in that: The ball milling mixing is carried out under the protection of an inert atmosphere, the ball milling time is 1-7 hours, the ball-to-material ratio is 40:1, and the rotation speed is 300-500r / min.

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