A catalytic electrode based on titanium aluminum carbon MAX phase ceramic membrane and its preparation method

Abstract

The present invention discloses a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane and a preparation method thereof. The method first prepares a high-strength porous titanium aluminum carbon MAX phase ceramic membrane by phase inversion tape casting combined with a reactive sintering method, and then performs hydrofluoric acid etching on the membrane to obtain a MXenes / MAX heterogeneous ceramic membrane with a unique layered structure inside. Subsequently, a catalytic layer is generated in situ on the membrane by impregnation, hydrothermal treatment, electrodeposition, and the like to optimize the catalytic activity of the electrode. The present invention combines phase inversion tape casting, reactive sintering, in-situ etching, hydrothermal treatment, electrodeposition, and the like to prepare a ceramic membrane electrode with excellent performance in electrocatalytic fields such as full hydrolysis, oxygen reduction, carbon dioxide reduction, electrochemical synthesis of ammonia, methanol oxidation, and urea oxidation. The preparation process is simple, the cost is low, and it is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to a catalytic electrode based on a titanium-aluminum-carbon MAX phase ceramic membrane and a preparation method thereof, belonging to the technical field of new energy material preparation. Background Art

[0002] With the continuous depletion of traditional fossil energy and the gradual deterioration of the global ecological environment, the development of new energy sources and advanced energy conversion and storage technologies has attracted increasing attention in various countries. Hydrogen, with its extremely high calorific value and energy density, and its combustion product, which is only water, is considered the most noteworthy new energy source. As the upstream component of the hydrogen energy industry chain and the cornerstone of the entire industry, the development of hydrogen production technology has become a hot topic in recent years. Among them, hydrogen production by water electrolysis is considered the most promising technology due to its environmental friendliness, ease of integration with other renewable energy sources (such as solar and wind energy), and high product purity. Furthermore, hydrogen fuel cell technology, located downstream of the hydrogen energy industry chain, also holds great promise in the energy conversion field. Electrocatalytic CO2 conversion technology utilizes renewable electricity to convert the greenhouse gas CO2 into high-value-added chemicals. This technology not only stores renewable energy but also helps reduce atmospheric CO2 levels, making it an advanced energy conversion and storage technology. Furthermore, several technologies, such as electrochemical ammonia synthesis, oxygen reduction, and methanol oxidation, while still in the early stages of development, also hold significant potential for future development. It is worth noting that in all of these areas, the development of high-performance, low-cost catalytic electrodes is a key focus.

[0003] Two-dimensional layered MXenes materials are considered to be an excellent catalyst carrier due to their excellent conductivity, rich surface groups and special layered structure. Catalytic electrodes based on MXenes materials can not only carry out rapid charge transfer, but also effectively regulate the catalytic performance of active sites by virtue of the interaction between MXenes and catalysts. As an emerging two-dimensional layered material, MXenes are mainly formed by etching the precursor MAX phase ceramic, and its typical chemical formula is M n+1 X n T x, where M is mainly a transition metal (such as titanium, molybdenum, vanadium, etc.), X is carbon or nitrogen, and T refers to surface functional groups such as hydroxyl groups. Although the development of MXenes-based catalytic electrodes has achieved very good results in recent years, there is a problem that has been plaguing this type of catalytic electrode. That is, during the application process, the two-dimensional layered MXenes materials often show a "self-stacking" phenomenon of stacking on each other, which causes a large number of active sites to be covered, ultimately resulting in less than ideal catalytic performance of the electrode. In addition, the current main preparation method for catalytic electrodes is to use a polymer binder to evenly coat the powder catalyst on the surface of a conductive substrate. This operation will cause a large number of active sites to be covered by the polymer and reduce the charge transfer rate of the catalytic electrode. Moreover, on such a catalytic electrode, the adhesion between the catalyst and the substrate is weak, and the catalyst is prone to fall off naturally during the use of the electrode, resulting in poor mechanical stability of the catalytic electrode. Summary of the Invention

[0004] The present invention aims to propose a catalytic electrode based on titanium aluminum carbon MAX phase ceramic membrane and its preparation method. The method first prepares a high-strength porous titanium aluminum carbon MAX phase ceramic membrane through phase transformation tape casting combined with reaction sintering, and then etches it with hydrofluoric acid to obtain a MXenes / MAX heterogeneous ceramic membrane with a unique layered structure inside. Then, a catalytic electrode with excellent performance and stability is prepared through impregnation, hydrothermal or electrodeposition methods.

[0005] To achieve the purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing a catalytic electrode based on a titanium-aluminum-carbon MAX phase ceramic membrane comprises the following steps:

[0007] (1) ball-milling titanium carbide, metallic titanium, metallic aluminum powder, a solvent, a dispersant, and a binder to prepare a uniform ceramic slurry;

[0008] (2) The ceramic slurry is degassed, cast, solidified by phase conversion, and naturally dried to obtain a ceramic membrane green body;

[0009] (3) sintering the ceramic membrane green body to obtain a porous titanium aluminum carbon MAX phase ceramic membrane;

[0010] (4) etching the porous titanium aluminum carbon MAX phase ceramic membrane in hydrofluoric acid to obtain a MXenes / MAX heterogeneous ceramic membrane with a unique layered structure;

[0011] (5) forming a catalytic layer on the MXenes / MAX heterogeneous ceramic membrane by impregnation treatment, hydrothermal treatment, vapor deposition, vapor phase conversion and / or electrodeposition treatment, thereby preparing a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane.

[0012] Furthermore, in step 1 (middle), the particle size of the titanium carbide, metallic titanium and metallic aluminum powders is 1-10 μm.

[0013] Furthermore, in step (1), the molar ratio of the titanium carbide, metallic titanium and metallic aluminum powders is 1:1.5-2:1-1.3.

[0014] Furthermore, in step (1), the solvent is N-methylpyrrolidone, the dispersant is at least one of KD-1 dispersant, polyvinylpyrrolidone and O-(2-aminopropyl)-O′-(2-methoxyethyl)polypropylene glycol, and the binder is at least one of polyvinyl alcohol, polyvinyl butyral and polyethersulfone.

[0015] Furthermore, in step (1), the rotation speed of the ball mill is 200-300 r min -1 , ball milling time is 36-50h.

[0016] Furthermore, in step (2), the ceramic slurry is first degassed for 0.5-1h, then poured into the mold tank, and the casting scraper height is adjusted to 0.5-1mm, and the casting speed is 30-100cm min -1 After the film is cast, it is placed in water to solidify for 18-24 hours, and then naturally dried to obtain a ceramic membrane green body.

[0017] Furthermore, in step (3), the sintering temperature raising step is: first, 3-5℃min -1 The heating rate is raised to 660-700℃, kept at this temperature for 5-10min, and then heated at 3-5℃min -1 The heating rate is raised to 820-850℃, kept at this temperature for 10-15min, and then heated at 3-5℃min -1 The heating rate was raised to 1000-1050℃, and then the temperature was increased at 2-3℃min -1 The temperature is raised to 1100-1500℃ at a heating rate of 0.5-3h, and the sintering atmosphere is argon or nitrogen.

[0018] Furthermore, in step (4), the mass concentration of the hydrofluoric acid is 30-40%, the etching temperature is 25-60° C., and the etching time is 2-24 h.

[0019] Furthermore, in step (4), the MXenes / MAX heterogeneous ceramic membrane uses titanium aluminum carbon (Ti3AlC2) MAX phase ceramic as the skeleton, and the layered Ti3C2 MXenes derived therefrom grow in situ on the surface of the skeleton to form a layered structure.

[0020] Furthermore, in step (5), the catalytic layer formed is a catalytic layer composed of at least one of platinum, ruthenium, molybdenum disulfide, molybdenum dioxide, nickel iron oxyhydroxide, nickel ferrite, and cobalt ferrite in the form of at least one of nanoparticles, nanosheets, and nanocubes, or a metal organic framework catalytic layer containing at least one transition metal of copper, nickel, and iron, or a molybdenum disulfide catalytic layer doped with at least one element of phosphorus, nitrogen, and selenium. The preparation method of the catalytic layer includes but is not limited to impregnation treatment, hydrothermal treatment, vapor deposition, vapor phase conversion, and / or electrodeposition treatment. For example, the corresponding catalytic layer can be formed by the following method:

[0021] The platinum catalyst layer was formed by impregnation treatment: the MXenes / MAX heterogeneous ceramic membrane was impregnated to a concentration of 0.01-0.5 mg mL -1 The MXenes / MAX heterogeneous ceramic membrane is formed by ultrasonicating the MXenes / MAX heterogeneous ceramic membrane in an ethanol solution of chloroplatinic acid for 6-24 hours, and then vacuum drying the MXenes / MAX heterogeneous ceramic membrane for 12-24 hours to obtain a catalytic electrode based on the titanium aluminum carbon MAX phase ceramic membrane. The catalytic layer formed is a platinum nanoparticle layer.

[0022] A molybdenum sulfide catalytic layer is formed by hydrothermal treatment: sodium molybdate dihydrate and thiourea are first added to a mixture of propionic acid and deionized water, stirred evenly, and then the mixed solution and the MXenes / MAX heterogeneous ceramic membrane are transferred to a hydrothermal kettle. The mixture is hydrothermally treated at 160-180°C for 8-12 hours to form a catalytic layer on the MXenes / MAX heterogeneous ceramic membrane, thereby obtaining a catalytic electrode based on the titanium aluminum carbon MAX phase ceramic membrane. The catalytic layer formed is a molybdenum sulfide nanosheet layer.

[0023] The nickel ferrite catalytic layer is formed using a hydrothermal treatment: ferric nitrate nonahydrate and nickel chloride hexahydrate are added to an N,N-dimethylformamide solution and magnetically stirred to obtain a mixed solution. The mixed solution and the MXenes / MAX heterogeneous ceramic membrane are then transferred to a hydrothermal reactor and hydrothermally treated at 180-200°C for 10-20 hours. This forms a catalytic layer on the MXenes / MAX heterogeneous ceramic membrane, resulting in a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane. The resulting catalytic layer is a layer of nickel ferrite nanoparticles.

[0024] The Cu-MOF catalytic layer is prepared by electrodeposition combined with hydrothermal treatment: sodium hydroxide and trimesic acid are first dissolved in deionized water to prepare a uniform electrolyte. A two-electrode system is then constructed using a MXenes / MAX heterogeneous ceramic membrane and a platinum electrode as the working electrode and counter electrode, respectively. The system is operated at a constant voltage of 2-5V for 0.5-2 hours to obtain the electrodeposited MXenes / MAX heterogeneous ceramic membrane. Subsequently, the electrodeposited MXenes / MAX heterogeneous ceramic membrane is placed in a copper nitrate solution, and the trimesic acid solution is slowly dripped into it. After magnetic stirring, the membrane is transferred to a hydrothermal reactor and hydrothermally reacted at 80-95°C for 15-20 hours. This forms a catalytic layer on the MXenes / MAX heterogeneous ceramic membrane, resulting in a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane. The formed catalytic layer is a Cu-MOF nanocube layer.

[0025] A phosphorus-doped molybdenum disulfide catalytic layer is formed by hydrothermal treatment: sodium molybdate dihydrate, thiourea, and sodium hypophosphite monohydrate are added to deionized water in a molar ratio of 1:5-7:1-3 and stirred evenly. Concentrated hydrochloric acid is then slowly added to adjust the pH to 1-3, and the mixture is stirred evenly. The prepared mixed solution is transferred to a hydrothermal reactor together with the MXenes / MAX heterogeneous ceramic membrane and hydrothermally reacted at 200°C for 24 hours to form a catalytic layer on the MXenes / MAX heterogeneous ceramic membrane, thereby obtaining a catalytic electrode based on the titanium aluminum carbon MAX phase ceramic membrane. The catalytic layer formed is a phosphorus-doped molybdenum disulfide nanosheet layer containing rich defects.

[0026] The catalytic electrode based on the titanium-aluminum-carbon MAX phase ceramic membrane prepared in this invention features layered Ti3C2 MXenes formed in situ on the surface of the titanium-aluminum-carbon (Ti3AlC2) ceramic, with the catalytic layer growing from the interlayers. It can be applied in electrocatalytic fields such as total hydrolysis, oxygen reduction, carbon dioxide reduction, electrochemical ammonia synthesis, methanol oxidation, and urea oxidation.

[0027] The present invention uses a simple and easy-to-use method to prepare a catalytic electrode based on titanium aluminum carbon MAX phase ceramics that exhibits excellent performance and stability in the field of electrocatalysis. Compared with the existing technology, the present invention has the following advantages:

[0028] The present invention first uses mature porous ceramic preparation technology to synthesize a porous titanium aluminum carbon MAX phase ceramic membrane, then obtains a MXenes / MAX heterogeneous ceramic membrane through etching treatment, and then uses an easily industrialized processing process to obtain a catalytic electrode based on the titanium aluminum carbon MAX phase ceramic membrane. Compared with other MXenes-based catalytic electrodes, the layered MXenes in the catalytic electrode prepared by the present invention are directly grown in situ on the surface of the MAX phase ceramic with excellent conductivity and high mechanical strength, avoiding the disordered stacking of two-dimensional layered MXenes, thereby exposing sufficient active sites. At the same time, the present invention grows the catalytic layer directly on the surface of the ceramic substrate through an in situ growth process, avoiding the use of a polymer binder. In addition, the mechanical / chemical stability of the porous ceramic membrane itself is very good, and the hydrophilicity and internal pore structure of its surface are easy to adjust, so that the performance of the catalytic electrode based on the ceramic membrane is easy to adjust, which can meet the needs of various electrocatalytic reactions. Finally, the preparation technology and process adopted by the present invention are relatively mature and low-cost, suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of (a) casting and (b) phase inversion molding in Example 1 of the present invention;

[0030] Figure 2 This is a cross-sectional scanning electron microscope image of the titanium aluminum carbon MAX phase ceramic film obtained after sintering at 1400°C for 1.5 hours in an argon atmosphere in Example 1 of the present invention, where (a) corresponds to a small magnification and (b) corresponds to a large magnification.

[0031] Figure 3 This is a scanning electron microscope image of the MXenes / MAX heterogeneous ceramic membrane obtained after treatment with hydrofluoric acid (40 wt.%) for 12 h in Example 1 of the present invention.

[0032] Figure 4 The Pt@TC / TAC-0.1 catalytic electrode prepared in Example 1 of the present invention ( Figure 4 (a)) and the MS@TC / TAC-12 catalytic electrode prepared in Example 2 ( Figure 4 Scanning electron microscope image of (b)).

[0033] Figure 5 Figure 3 is a diagram of the electrochemical testing device used in Examples 1, 2, and 3 of the present invention (a is the overall device, b is a partial enlarged view of the working electrode), wherein the working electrode is the prepared ceramic electrode, the reference electrode is a saturated silver / silver chloride (acidic environment) or a mercury / mercuric oxide electrode (alkaline environment), and the counter electrode is a graphite rod.

[0034] Figure 6Figure 3 is a diagram of the electrochemical testing device used in Examples 4 and 5 of the present invention, wherein the working electrode is the prepared ceramic electrode, the reference electrode is a saturated silver / silver chloride (acidic or neutral environment) or a mercury / mercuric oxide electrode (alkaline environment), the counter electrode is a platinum sheet electrode, and the ion exchange membrane is Nafion N117.

[0035] Figure 7 The LSV curve of hydrogen evolution of the catalytic electrode based on titanium aluminum carbon MAX phase ceramic membrane prepared in Example 2 ( Figure 7 (a)) and overpotential ( Figure 7 (b) in the figure.

[0036] Figure 8 The oxygen evolution LSV curve of the catalytic electrode based on the titanium aluminum carbon MAX phase ceramic membrane prepared in Example 3 ( Figure 8 (a)) and the corresponding Tafel slope ( Figure 8 (b) in the figure.

[0037] Figure 9 The Faraday efficiency (FE) of the catalytic electrode based on titanium aluminum carbon MAX phase ceramic membrane prepared in Example 4 for the conversion of CO2 to formic acid in a CO2-saturated 0.5MKHCO3 electrolyte is Formate ) and the corresponding current density.

[0038] Figure 10 The yield and Faradaic efficiency of electrochemical synthesis of NH3 in N2-saturated 0.1MNa2SO4 electrolyte of the catalytic electrode based on titanium aluminum carbon MAX phase ceramic membrane prepared in Example 5. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.

[0040] Example 1

[0041] In this embodiment, a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane is prepared according to the following steps:

[0042] (1) Ceramic slurry: Titanium carbide powder with a particle size distribution range of 5-10 μm and metal titanium and metal aluminum powder with a particle size distribution range of 1-3 μm were mixed in a molar ratio of 1:1.5:1.3, and then 3% of the total mass of the above powders were added as a dispersant of O-(2-aminopropyl)-O′-(2-methoxyethyl) polypropylene glycol, 11.11% of polyethersulfone as a binder, and 30% of the total mass of the slurry as a solvent of N-methylpyrrolidone. The mixture was then poured into a ball mill for ball milling at a speed of 280 rmin. -1 , the ball milling time is 48h.

[0043] (2) After degassing the ceramic slurry for 30 minutes, pour it into the casting mold tank, adjust the scraper height to 1.0 mm, and control the casting speed to 30 cm min -1 After casting, the membrane was placed horizontally in a water tank. After standing for 18 hours, the sample was removed from the water and dried at room temperature for 7 days to obtain a titanium aluminum carbon MAX phase ceramic membrane green body.

[0044] (3) Place the titanium aluminum carbon MAX phase ceramic membrane green body in a corundum tube furnace with argon gas flowing at 3℃min -1 The heating rate was raised to 660℃, kept at this temperature for 5min, and then -1 The heating rate was raised to 820℃, kept at this temperature for 10min, and then the temperature was raised to 820℃ at a rate of 5℃min. -1 The heating rate was increased to 1000℃, and then the heating rate was reduced to 2℃min -1 , heating to 1400℃ and keeping warm for 1.5h, a porous titanium aluminum carbon MAX phase ceramic membrane is obtained, and its cross-sectional scanning electron microscope image is shown in FIG. Figure 2 As shown, it can be seen that the ceramic membrane has an asymmetric finger-like straight-through pore structure with a pore diameter of 80-100 μm, and there are many small pores of 0.5-2 μm inside the finger-like pores, indicating the existence of a hierarchical porous structure.

[0045] (4) The porous titanium aluminum carbon MAX phase ceramic membrane was placed in a hydrofluoric acid solution with a temperature of 25°C and a mass concentration of 40% and etched for 12 hours to obtain a MXenes / MAX heterogeneous ceramic membrane with a special layered structure inside. The scanning electron microscope image is shown in FIG. Figure 3 As shown, the special layered structure inside the ceramic membrane can be seen.

[0046] (5) The MXenes / MAX heterogeneous ceramic membrane was immersed in water with concentrations of 0.025, 0.05, 0.1, and 0.2 mg mL -1 The membrane was placed in a chloroplatinic acid ethanol solution and ultrasonically treated for 24 hours. After being taken out and ultrasonically cleaned three times, it was then vacuum-dried at 60°C for 24 hours to form a platinum nanoparticle catalytic layer on the MXenes / MAX heterogeneous ceramic membrane. Catalytic electrodes based on titanium aluminum carbon MAX phase ceramic membrane were obtained, which were recorded as Pt@TC / TAC-0.025, Pt@TC / TAC-0.05, Pt@TC / TAC-0.1, and Pt@TC / TAC-0.2, respectively.

[0047] like Figure 4 As shown in (a), the platinum particles in the obtained Pt@TC / TAC-0.1 sample are evenly distributed on the surface of the catalytic electrode and in the special layered structure formed by etching.

[0048] Subsequently, a three-electrode system was constructed using the prepared catalytic electrode as the working electrode, saturated silver / silver chloride as the reference electrode, and graphite as the counter electrode ( Figure 5 ), and electrochemical hydrogen evolution tests were carried out in acidic (0.5M H2SO4) electrolyte. The results are shown in Table 1. The hydrogen evolution performance of the catalytic electrode first increases with the increase of chloroplatinic acid concentration, and then increases at 0.1 mg mL -1 The performance of the Pt@TC / TAC-0.1 electrode reaches a peak at 10 mA cm -2 The overpotential required for the current density is only 50mV, which is much lower than that of other catalytic electrodes, showing excellent hydrogen evolution activity. In addition, in order to verify the industrial application prospects of the prepared catalytic electrode, this example tests the electrode at a large current density (1000mAcm -2 ) were also compared. Among them, the Pt@TC / TAC-0.1 electrode output 1000mA cm -2 The overpotential required for the current density is only 346 mV, which is still much smaller than that of the other electrodes.

[0049] Table 1. HER performance of the Pt@TC / TAC-X (X: mass concentration of chloroplatinic acid) catalytic electrode prepared in Example 1 in 0.5MH2SO4 medium

[0050]

[0051] Example 2

[0052] In this embodiment, a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane is prepared according to the following steps:

[0053] Step (1) to step (3): the same as in Example 1.

[0054] Step (4): Place the porous titanium aluminum carbon MAX phase ceramic membrane in a hydrofluoric acid solution with a temperature of 25°C and a mass concentration of 40%, and etch it for 8, 10, and 12 hours, respectively, to obtain MXenes / MAX heterogeneous ceramic membranes with a special layered structure inside, which are recorded as TC / TAC-8, TC / TAC-10, and TC / TAC-12.

[0055] Step (5): Sodium molybdate dihydrate and thiourea in a molar ratio of 1:8 are added to a mixture of propionic acid and deionized water in a volume ratio of 1:2, stirred evenly, and then transferred into a hydrothermal kettle together with the MXenes / MAX heterogeneous ceramic membrane prepared in the previous step. The mixture is hydrothermally reacted at 180°C for 8 hours to form a molybdenum sulfide nanosheet catalytic layer on the MXenes / MAX heterogeneous ceramic membrane, thereby obtaining catalytic electrodes based on titanium aluminum carbon MAX phase ceramic membranes, which are named MS@TC / TAC-8, MS@TC / TAC-10, and MS@TC / TAC-12, respectively.

[0056] The surface morphology of the catalytic electrode MS@TC / TAC-12 is shown in Figure 2. Figure 4 As shown in (b), petal-shaped MoS nanosheets are uniformly grown on the surface of the catalytic electrode. Figure 4 In the enlarged image of (b), it can be clearly observed that the MoS nanosheets have been inserted into the interlayer of the layered structure formed by etching. Figure 5 As shown, the working electrode is the prepared catalytic electrode, the reference electrode is a saturated silver / silver chloride electrode, the counter electrode is a graphite electrode, and the electrolyte is 0.5 M H2SO4. Figure 7 The LSV curves of the catalytic electrodes show that the performance of the catalytic electrodes gradually improves with the continuous extension of etching time. Among them, the MS@TC / TAC-12 electrode shows the best hydrogen evolution activity, and can output 10mA cm at overpotentials of 137mV, 259mV, and 278mV, respectively. -2 、1000mAcm -2 and 2000mA cm -2 The current density of the electrodes was much lower than that of the MS@TC / TAC-8 (168 mV, 296 mV, and 321 mV) and MS@TC / TAC-10 (142 mV, 283 mV, and 305 mV).

[0057] Example 3

[0058] In this embodiment, a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane is prepared according to the following steps:

[0059] Step (1) to step (4): the same as in Example 1.

[0060] Step (5): Ferric nitrate nonahydrate and nickel chloride hexahydrate were added to the N,N-dimethylformamide solution at a molar ratio of 1:1 and magnetically stirred for 0.5 h to obtain a uniform mixed solution. The MXenes / MAX heterogeneous ceramic membrane prepared above and the mixed solution were then transferred to a hydrothermal reactor and hydrothermally treated at 200°C for 10, 15, and 20 h, respectively, to form a nickel ferrite nanoparticle catalytic layer on the MXenes / MAX heterogeneous ceramic membrane, thereby obtaining catalytic electrodes based on titanium aluminum carbon MAX phase ceramic membranes, which were designated as Ni / Fe-200-10, Ni / Fe-200-15, and Ni / Fe-200-20, respectively.

[0061] like Figure 5 As shown in the figure, the prepared catalytic electrode was used as the working electrode, the mercury / mercuric oxide electrode was used as the reference electrode, and graphite was used as the counter electrode to conduct electrochemical oxygen evolution test in alkaline (1M KOH) medium. Figure 8 As shown in Table 2, the Ni / Fe-200-15 electrode outputs 10 mA cm-2 The required overpotential is 225 mV and the Tafel slope is 79 mV dec -1 , which are better than Ni / Fe-200-10 (265mV, 82mV dec -1 ) and Ni / Fe-200-20 electrode (303mV, 114mV dec -1 ), showing the best oxygen evolution performance.

[0062] Table 2. OER performance of the Ni / Fe-200-x (x: hydrothermal time) electrode prepared in Example 3 in 1M KOH medium.

[0063]

[0064] Example 4

[0065] In this embodiment, a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane is prepared according to the following steps:

[0066] Step (1) to step (4): the same as in Example 1.

[0067] Step (5): A two-electrode system was constructed using the MXenes / MAX heterogeneous ceramic membrane as the working electrode, a platinum electrode as the counter electrode, and a mixed solution of trimesic acid and sodium hydroxide (mass ratio 7:4) as the electrolyte. Subsequently, the working electrode was subjected to electrodeposition at a constant voltage of 5 V for 2 h to obtain a MXenes / MAX heterogeneous ceramic membrane loaded with trimesic acid.

[0068] Step (6): First, prepare the -1 The copper nitrate aqueous solution and the concentration are 0.018g mL -1 Secondly, the electrodeposited MXenes / MAX heterogeneous ceramic membrane was placed in a copper nitrate solution, and the trimesic acid ethanol solution was slowly dripped into it until the volume ratio of the two solutions reached 1:1. It was then magnetically stirred for 0.5 hours and then transferred to a hydrothermal reactor for hydrothermal reaction at 95°C for 15 hours, forming a Cu-MOF nanocube catalytic layer on the MXenes / MAX heterogeneous ceramic membrane. This resulted in a catalytic electrode based on the titanium aluminum carbon MAX phase ceramic membrane, which was designated Cu-BTC-95-15.

[0069] like Figure 6As shown, the prepared Cu-BTC-95-15 electrode was inserted into an H-type electrolytic cell as the working electrode, with a platinum electrode as the counter electrode and a saturated silver / silver chloride electrode as the reference electrode. The carbon dioxide reduction test was carried out in a CO2-saturated 0.5M KHCO3 electrolyte. The prepared catalytic electrode exhibited excellent electrocatalytic carbon dioxide reduction activity and good selectivity for formic acid. Figure 9 The Faradaic efficiency and corresponding partial current density of the Cu-BTC-95-15 electrode for converting CO2 into formic acid products in the voltage range of -0.9 to -1.3 V (vs. RHE) are shown. As the voltage increases from -0.9 V (vs. RHE) to -1.3 V (vs. RHE), the Faradaic efficiency (FE Formate ) gradually increased from an initial 19%, reaching a peak of 52% at -1.2 V (vs. RHE), and then decreased to 47% at -1.3 V (vs. RHE). In terms of current density, the partial current density corresponding to the formic acid product steadily increased with the increase in applied voltage, reaching a maximum of 20.6 mA cm at -1.3 V (vs. RHE). -2 .

[0070] Example 5

[0071] In this embodiment, a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane is prepared according to the following steps:

[0072] Step (1) to step (4): the same as in Example 1.

[0073] Step (5): Sodium molybdate dihydrate, thiourea, and sodium hypophosphite monohydrate were added to deionized water in a molar ratio of 1:5:1 and stirred for 10 minutes. Then, concentrated hydrochloric acid was slowly added dropwise to adjust the pH value to ~2, and stirring was continued for 30 minutes. The prepared mixed solution and the MXenes / MAX heterogeneous ceramic membrane were transferred to a hydrothermal reactor and hydrothermally reacted at 200°C for 24 hours to form a phosphorus-doped molybdenum disulfide nanosheet catalytic layer on the MXenes / MAX heterogeneous ceramic membrane, thereby obtaining a catalytic electrode based on the titanium aluminum carbon MAX phase ceramic membrane, named TC / TAC-MS-P-1.

[0074] like Figure 6 As shown, the prepared TC / TAC-MS-P-1 electrode was inserted into an H-type electrolytic cell as a working electrode, a platinum sheet electrode was used as a counter electrode, and a saturated silver / silver chloride electrode was used as a reference electrode. Electrochemical ammonia synthesis test was carried out in a 0.1M Na2SO4 electrolyte saturated with N2. Figure 10The results show that within the voltage range of -0.4 to -0.8 V (vs. RHE), the yield of electrochemical ammonia synthesis gradually increases with the increase of applied voltage, reaching a peak value (56 μg mg) at -0.6 V (vs. RHE). -1 cat. h -1 ), and as the voltage is increased, the yield begins to gradually decrease. Within the same voltage range, the Faradaic efficiency and yield of electrochemical ammonia synthesis follow the same trend, also reaching a peak (10.6%) at -0.6 V (vs. RHE).

[0075] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any person skilled in the art can, without departing from the spirit and technical solution of the present invention, use the methods and technical contents disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a catalytic electrode based on titanium aluminum carbon MAX phase ceramic membrane, characterized in that: The steps include: (1) Mix titanium carbide, titanium metal, aluminum metal powders with solvent, dispersant, and binder by ball milling to prepare a uniform ceramic slurry; (2) The ceramic slurry is degassed, cast, solidified by phase transformation, and naturally dried to obtain a ceramic membrane green body; (3) sintering the ceramic membrane green body to obtain a porous titanium aluminum carbon MAX phase ceramic membrane; (4) etching the porous titanium aluminum carbon MAX phase ceramic membrane in hydrofluoric acid to obtain a MXenes / MAX heterogeneous ceramic membrane with a layered structure inside; the mass concentration of the hydrofluoric acid is 30-40%, the etching temperature is 25-60 ° C, and the etching time is 2-24 h; (5) forming a catalytic layer on the MXenes / MAX heterogeneous ceramic membrane, i.e., preparing a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane; the catalytic layer is prepared by impregnation treatment, hydrothermal treatment, vapor deposition, vapor phase conversion and / or electrodeposition treatment, and the formed catalytic layer is a catalytic layer composed of at least one of platinum, ruthenium, molybdenum disulfide, molybdenum dioxide, nickel iron oxyhydroxide, nickel ferrite and cobalt ferrite in the form of at least one of nanoparticles, nanosheets and nanocubes, or a metal organic framework catalytic layer containing at least one transition metal of copper, nickel and iron, or a molybdenum disulfide catalytic layer doped with at least one element of phosphorus, nitrogen and selenium.

2. The method for preparing a catalytic electrode based on a titanium-aluminum-carbon MAX phase ceramic membrane according to claim 1, characterized in that: In step (1), the molar ratio of the titanium carbide, metallic titanium and metallic aluminum powders is 1:1.5-2:1-1.

3.

3. The method for preparing a catalytic electrode based on a titanium-aluminum-carbon MAX phase ceramic membrane according to claim 1, characterized in that: In step (1), the solvent is N-methylpyrrolidone, the dispersant is at least one of KD-1 dispersant, polyvinylpyrrolidone and O-(2-aminopropyl)-O′-(2-methoxyethyl)polypropylene glycol, and the binder is at least one of polyvinyl alcohol, polyvinyl butyral and polyethersulfone.

4. The method for preparing a catalytic electrode based on a titanium-aluminum-carbon MAX phase ceramic membrane according to claim 1, characterized in that: In step (1), the ball milling speed is 200-300 r min -1 , ball milling time is 36-50 h.

5. The method for preparing a catalytic electrode based on a titanium-aluminum-carbon MAX phase ceramic membrane according to claim 1, characterized in that: In step (2), the ceramic slurry is first degassed for 0.5-1 h, then poured into the mold tank, and the casting scraper height is adjusted to 0.5-1 mm, and the casting speed is 30-100 cm min -1 After the film is cast, it is placed in water to solidify for 18-24 hours and then dried naturally to obtain the ceramic membrane green body.

6. The method for preparing a catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane according to claim 1, characterized in that: In step (3), the sintering temperature is raised as follows: first, at 3-5 °C min -1 The heating rate was increased to 660-700 ℃, kept at this temperature for 5-10 min, and then heated at 3-5 ℃ min -1 The temperature was raised to 820-850 °C at a rate of 10-15 min, and then heated at a rate of 3-5 °C min -1 The temperature was raised to 1000-1050 °C at a rate of 2-3 °C min -1 The temperature is raised to 1100-1500 °C at a heating rate of 1000-2000 °C and kept at this temperature for 0.5-3 h. The sintering atmosphere is argon or nitrogen.

7. The method for preparing a catalytic electrode based on a titanium-aluminum-carbon MAX phase ceramic membrane according to claim 1, characterized in that: In step (4), the MXenes / MAX heterogeneous ceramic membrane uses titanium aluminum carbon MAX phase ceramic as a skeleton, and the layered MXenes derived therefrom grow in situ on the surface of the skeleton to form a layered structure.

8. A catalytic electrode based on a titanium aluminum carbon MAX phase ceramic membrane prepared by the preparation method according to any one of claims 1 to 7.

9. An application of the catalytic electrode based on the titanium aluminum carbon MAX phase ceramic membrane according to claim 8, characterized in that: The invention is applied to the electrocatalytic field including one of full hydrolysis, oxygen reduction, carbon dioxide reduction, electrochemical ammonia synthesis, methanol oxidation or urea oxidation.

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