A Ti3C2TxMXene-supported copper-aluminum nanoalloy catalyst, its preparation method and application

Abstract

The application discloses a Ti3C2T x The application discloses a Ti3C2T x MXene solid powder; (4) dissolving copper salt and aluminum salt in deionized water and magnetically stirring; (5) adding Ti3C2T x MXene solid powder into the copper-aluminum salt solution, ultrasonicating, dropwise adding a NaBH4 solution, magnetically stirring, centrifugally cleaning, and freeze-drying, so that the catalyst is obtained. The catalyst can effectively inhibit a hydrogen evolution side reaction in an electrocatalytic carbon dioxide reduction reaction, reduce an overpotential of CO2 reduction, improve energy efficiency, and thus enhances CO2 reduction reaction efficiency.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic carbon dioxide reduction technology, specifically to a Ti3C2T x MXene-supported copper-aluminum nanoalloy catalyst, its preparation method, and its application in electrocatalytic carbon dioxide reduction reaction. Background Technology

[0002] With the acceleration of industrialization and rapid global economic growth, carbon dioxide emissions are constantly increasing, exacerbating global climate change and the greenhouse effect. Traditional fossil fuel consumption patterns lead to a severe waste of carbon resources, while electrocatalytic carbon dioxide reduction technology can convert carbon dioxide into chemicals and fuels, thereby achieving the effective utilization of carbon resources and the establishment of a circular economy. Therefore, catalyst research and development has become one of the key areas in this technological field, involving catalyst structure design, regulation of active sites, and optimization of catalyst supports.

[0003] Ti3C2T x MXene is an emerging two-dimensional material with excellent electrical conductivity, chemical stability, and a large specific surface area, and it contains abundant functional groups, thus it is widely used in the field of catalyst supports. However, in supported Ti3C2T... x There are still some problems to be overcome in the preparation of MXene electrocatalysts, such as: severe hydrogen evolution reaction in electrocatalytic reaction; easy agglomeration of single active metals on the support surface; and complex preparation process.

[0004] Therefore, how to improve the load-bearing capacity of Ti3C2T x Improving the reaction efficiency of MXene electrocatalysts and simplifying their preparation process are problems that urgently need to be solved by researchers in this field. Summary of the Invention

[0005] In view of this, in order to solve this problem, the present invention aims to provide a Ti3C2T x This invention discloses a method for synthesizing MXene supports and a method for preparing copper-aluminum nano-alloy catalysts loaded on these supports, while also providing the application of this catalyst in electrocatalytic carbon dioxide reduction. The invention utilizes a simple wet chemical impregnation method to synthesize Ti3C2T... x Using MXene as a support and combining it with copper-aluminum nano-alloys as the active component, a nano-alloy electrocatalyst was synthesized. This catalyst can effectively suppress hydrogen evolution side reactions, improve catalyst stability and activity, and thus enhance the efficiency of electrocatalytic carbon dioxide reduction reaction.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A Ti3C2T xThe preparation method of MXene-supported copper-aluminum nano-alloy catalyst specifically includes the following steps:

[0008] (1) First, mix hydrochloric acid with LiF (lithium fluoride) and stir until uniform. Then, add Ti3AlC2 (titanium aluminum carbide) precursor, heat in a water bath, and stir magnetically to obtain dispersion A.

[0009] (2) First, wash dispersion A by centrifugation with deionized water, then wash it by centrifugation with hydrochloric acid, and finally wash it with deionized water to obtain dispersion B.

[0010] (3) Shake dispersion B until homogeneous, sonicate under ice bath conditions (Ar) and centrifuge, take the upper suspension and freeze-dry to obtain Ti3C2T x MXene solid powder, for later use;

[0011] (4) Dissolve copper and aluminum salts in deionized water and stir magnetically to obtain a copper-aluminum salt solution;

[0012] (5) Add Ti3C2T to the copper-aluminum salt solution x MXene solid powder was ultrasonicated, NaBH4 (sodium borohydride) solution was added dropwise, magnetically stirred, centrifuged and washed, and then freeze-dried to obtain Ti3C2T. x MXene-supported copper-aluminum nano-alloy catalyst.

[0013] Furthermore, in step (1) above, the concentration of hydrochloric acid is 9M; the mass-to-volume ratio of hydrochloric acid, LiF and Ti3AlC2 precursor is 45mL:(3.6-4.0)g:2.0g; the water bath heating temperature is 45℃; the magnetic stirring speed is 450-600r / min, and the time is 48h.

[0014] Furthermore, in step (2) above, the concentration of hydrochloric acid is 1-2M; the centrifugal washing speed is 3500-10000r / min, the time is 5-15min, and the number of times is 2; the washing is carried out until the pH is 6-7.

[0015] The further beneficial effect of the above method is that the purpose of centrifugation washing with deionized water and hydrochloric acid in sequence is to remove excess LiF. During the centrifugation washing process, the rotation speed can be appropriately increased to eventually wash the pH to neutral. After the pH reaches neutral, spontaneous stratification will occur in the centrifuge tube, that is, the upper suspension will become turbid.

[0016] Furthermore, in step (3) above, the ultrasonication time is 60 min; the centrifugation speed is 3500 r / min, and the time is 10-60 min; the freeze-drying time is 48 h; Ti3C2T xMXene solid powder has a single-layer or single- or few-layer lamellar structure with a thickness of 1-2 nm. The ultrasonic exfoliation process must be carried out under ice bath conditions, and the ultrasonic temperature should generally not exceed 30°C. The water should be changed every 20 minutes.

[0017] Furthermore, in step (4) above, the copper salt is copper chloride, copper nitrate trihydrate or copper acetylacetonate; the aluminum salt is aluminum nitrate nonahydrate; the mass ratio of copper salt to aluminum salt is 1:1; the volume of deionized water is 20 mL; and the magnetic stirring time is 10-30 min.

[0018] The further beneficial effect of the above-mentioned method is that the copper and aluminum salts selected in this invention are inexpensive, which can effectively control costs. Magnetic stirring ensures that the copper and aluminum salts are fully dissolved in deionized water.

[0019] Furthermore, in step (5) above, Ti3C2T x The amount of MXene solid powder added is 100-200 mg; the ultrasonic time is 30-60 min; the concentration of NaBH4 solution is 1 M, and the amount added is 2-5 mL; the magnetic stirring time is 4 h; and the freeze-drying time is 24-48 h.

[0020] Ti3C2T prepared by the above method x MXene-supported copper-aluminum nano-alloy catalyst.

[0021] Ti3C2T prepared by the above method x Application of MXene-supported copper-aluminum nanoalloy catalysts in electrocatalytic carbon dioxide reduction reaction.

[0022] Furthermore, the above application specifically includes the following steps:

[0023] (1) Ti3C2T x MXene-supported copper-aluminum nano-alloy catalyst, isopropanol, deionized water and Nafion solution were mixed evenly and ultrasonically dispersed to obtain a dispersion.

[0024] (2) The dispersion was evenly dropped onto carbon paper and allowed to air dry naturally before being used as the working electrode.

[0025] (3) Using a silver / silver chloride electrode as the reference electrode and a graphite rod electrode as the counter electrode, a Nafion 117 proton exchange membrane was used, and the electrolyte was a KHCO3 solution. An H-type electrolytic cell was used as the reactor, and the electrocatalytic carbon dioxide reduction reaction was carried out in an electrochemical workstation.

[0026] Furthermore, in step (1) above, the Ti3C2T xThe mass-to-volume ratio of MXene-supported copper-aluminum nano-alloy catalyst, isopropanol, deionized water, and Nafion solution was 2 mg:300 μL:100 μL:20 μL; the ultrasonic dispersion time was 30-60 min; in step (2), the carbon paper size was 1 × 1 cm. 2 The loading of the working electrode is 0.2-1.0 mg / cm³. 2 In step (3), the concentration of the KHCO3 solution is 0.1M.

[0027] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. The preparation method of this invention includes two-dimensional Ti3C2T x Synthesis of MXene supports and preparation of nanoscale copper-aluminum nanoalloys loaded on the supports, including two-dimensional Ti3C2T x MXene supports were synthesized via hydrochloric acid + LiF, and then copper and aluminum salts were impregnated onto Ti3C2T via wet chemical impregnation. x In the dispersion, after sonication, NaBH4 solution was added, followed by stirring, centrifugation, and freeze-drying to obtain a solid catalyst powder. This method is simple and easy to implement, synthesized via wet chemical impregnation, and by effectively controlling the synthesis conditions of the catalyst, Ti3C2T can be obtained. x MXene-supported copper-aluminum nano-alloy catalyst.

[0029] 2. The Ti3C2T synthesized in this invention x The MXene carrier has a single-layer or single- or few-layer sheet structure with a thickness of 1-2 nm, and the copper-aluminum nano-alloy has a size of 20-30 nm, which increases the exposure area of ​​active sites.

[0030] 3. The Ti3C2T prepared by this invention x MXene-supported copper-aluminum nano-alloy catalysts can effectively suppress hydrogen evolution side reactions, reduce the overpotential of CO2 reduction, and improve energy efficiency in electrocatalytic carbon dioxide reduction, thereby enhancing the efficiency of CO2 reduction reaction. Attached Figure Description

[0031] Figure 1 Ti3C2T prepared in Example 1 x High-resolution transmission electron microscopy (HR-TEM) image of MXene-supported copper-aluminum nanoalloy catalyst;

[0032] Figure 2 Ti3C2T prepared in Example 1 x Linear sweep curve (LSV) of MXene-supported copper-aluminum nano-alloy catalyst in CO2-saturated 0.5 MkHCO3;

[0033] Figure 3 Ti3C2T prepared in Example 1 x Hydrogen evolution Faraday efficiency plot of MXene-supported copper-aluminum nanoalloy catalyst in the range of -1.4 to -1.0 V (V vs. RHE);

[0034] Figure 4 Ti3C2T prepared in Example 1 x Formic acid faradaic efficiency plot of MXene-supported copper-aluminum nanoalloy catalyst at -1.1V (V vs. RHE). Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] Ti3C2T x The preparation method of MXene-supported copper-aluminum nano-alloy catalyst specifically includes the following steps:

[0038] (1) First, mix 45 mL of 9 M hydrochloric acid with 3.6 g of LiF in a polytetrafluoroethylene bottle and stir evenly. Then add 2.0 g of Ti3AlC2 precursor, heat in a water bath at 45 °C, and magnetically stir at 450 r / min for 48 h to obtain dispersion A.

[0039] (2) First, wash dispersion A by centrifuging twice with deionized water at 3500 r / min for 15 min each time, then wash twice with 1M hydrochloric acid at 3500 r / min for 15 min each time, and finally wash with deionized water 5-8 times until the pH is 6-7 to obtain dispersion B.

[0040] (3) Shake dispersion B evenly, and then perform ultrasonic exfoliation in an ice bath for 60 min under Ar conditions. After centrifugation at 3500 r / min for 15 min, take the upper suspension and freeze-dry for 48 h to obtain Ti3C2T with a single-layer few-layer lamellar structure and a thickness of 1-2 nm. x MXene solid powder, for later use;

[0041] (4) Dissolve copper chloride and aluminum nitrate nonahydrate in 20 mL of deionized water at a mass ratio of 1:1 and stir magnetically for 20 min to obtain a copper-aluminum salt solution.

[0042] (5) Add 100 mg Ti3C2T to the copper-aluminum salt solution x MXene solid powder was sonicated for 60 min, 2 mL of 1 M NaBH4 solution was added dropwise, magnetic stirring was carried out for 4 h, centrifuged and washed, and then freeze-dried for 24 h to obtain Ti3C2T. x MXene-supported copper-aluminum nano-alloy catalyst.

[0043] Example 2

[0044] Ti3C2T x The preparation method of MXene-supported copper-aluminum nano-alloy catalyst specifically includes the following steps:

[0045] (1) First, mix 45 mL of 9 M hydrochloric acid with 3.6 g of LiF in a polytetrafluoroethylene bottle and stir evenly. Then add 2.0 g of Ti3AlC2 precursor, heat in a water bath at 45 °C, and magnetically stir at 450 r / min for 48 h to obtain dispersion A.

[0046] (2) First, wash dispersion A by centrifuging twice with deionized water at 3500 r / min for 15 min each time, then wash twice with 1M hydrochloric acid at 3500 r / min for 15 min each time, and finally wash with deionized water 5-8 times until the pH is 6-7 to obtain dispersion B.

[0047] (3) Shake dispersion B evenly, and then perform ultrasonic exfoliation in an ice bath for 60 min under Ar conditions. After centrifugation at 3500 r / min for 15 min, take the upper suspension and freeze-dry for 48 h to obtain Ti3C2T with a single-layer few-layer lamellar structure and a thickness of 1-2 nm. x MXene solid powder, for later use;

[0048] (4) Dissolve copper nitrate trihydrate and aluminum nitrate nonahydrate in 20 mL of deionized water at a mass ratio of 1:1 and stir magnetically for 20 min to obtain a copper-aluminum salt solution.

[0049] (5) Add 200 mg Ti3C2T to the copper-aluminum salt solution x MXene solid powder was sonicated for 60 min, 4 mL of 1 M NaBH4 solution was added dropwise, magnetic stirring was carried out for 4 h, centrifuged and washed, and then freeze-dried for 24 h to obtain Ti3C2T. x MXene-supported copper-aluminum nano-alloy catalyst.

[0050] Example 3

[0051] Ti3C2T x The preparation method of MXene-supported copper-aluminum nano-alloy catalyst specifically includes the following steps:

[0052] (1) First, mix 45 mL of 9 M hydrochloric acid with 3.6 g of LiF in a polytetrafluoroethylene bottle and stir evenly. Then add 2.0 g of Ti3AlC2 precursor, heat in a water bath at 45 °C, and magnetically stir at 450 r / min for 48 h to obtain dispersion A.

[0053] (2) First, wash dispersion A by centrifuging twice with deionized water at 3500 r / min for 15 min each time, then wash twice with 1M hydrochloric acid at 3500 r / min for 15 min each time, and finally wash with deionized water 5-8 times until the pH is 6-7 to obtain dispersion B.

[0054] (3) Shake dispersion B evenly, and then perform ultrasonic exfoliation in an ice bath for 60 min under Ar conditions. After centrifugation at 3500 r / min for 15 min, take the upper suspension and freeze-dry for 48 h to obtain Ti3C2T with a single-layer few-layer lamellar structure and a thickness of 1-2 nm. x MXene solid powder, for later use;

[0055] (4) Dissolve copper acetylacetonate and aluminum nitrate nonahydrate in 20 mL of deionized water at a mass ratio of 1:1 and stir magnetically for 20 min to obtain a copper-aluminum salt solution.

[0056] (5) Add 200 mg Ti3C2T to the copper-aluminum salt solution x MXene solid powder was sonicated for 60 min, 4 mL of 1 M NaBH4 solution was added dropwise, magnetic stirring was carried out for 4 h, centrifuged and washed, and then freeze-dried for 24 h to obtain Ti3C2T. x MXene-supported copper-aluminum nano-alloy catalyst.

[0057] Performance testing

[0058] 1. HR-TEM image

[0059] Ti3C2T prepared in Example 1 x High-resolution transmission electron microscopy (HR-TEM) image of MXene-supported copper-aluminum nanoalloy catalyst as shown below Figure 1 As shown.

[0060] Depend on Figure 1 It can be seen that the dispersion in Ti3C2T x The copper-aluminum nano-alloys on the MXene substrate are 20-30 nm in size and relatively uniformly dispersed, indicating that the Ti3C2T prepared in Example 1 is of good quality. x MXene-supported copper-aluminum nano-alloy catalysts can be relatively uniformly dispersed in a single-layer few-layer Ti3C2T x On MXene nanosheets.

[0061] 2. Electrocatalytic carbon dioxide reduction performance test

[0062] The performance test specifically includes the following steps:

[0063] (1) 2 mg of Ti3C2T prepared in Example 1 x The MXene-supported copper-aluminum nano-alloy catalyst was mixed with 300 μL isopropanol, 100 μL deionized water and 20 μL Nafion solution, and then ultrasonically dispersed for 60 min to obtain a dispersion.

[0064] (2) Divide 100 μL of the dispersion into three equal drops at a ratio of 4:3:3 and drop them evenly onto a 1×1 cm² surface. 2 The carbon paper was air-dried and then used as the working electrode with a loading of 0.5 mg / cm². 2 ;

[0065] (3) Using a silver / silver chloride electrode as the reference electrode and a graphite rod electrode as the counter electrode, a Nafion 117 proton exchange membrane was used. The electrolyte was a 0.1M KHCO3 solution. An H-type electrolytic cell was used as the reactor. The electrocatalytic carbon dioxide reduction reaction was carried out in an electrochemical workstation.

[0066] The results are as follows Figure 2-4 As shown.

[0067] Depend on Figure 2-4 It can be seen that the Ti3C2T prepared in Example 1 x MXene-supported copper-aluminum nanoalloy catalysts exhibit high electrocatalytic activity, with a local current density reaching -29.4 mA / cm² in an H₂ cell. 2 Furthermore, the hydrogen evolution Faraday efficiency is suppressed to below 30% in a wide range of -1.4 to -1.0 V (V vs. RHE), and the formic acid production Faraday efficiency is 68% at -1.1 V (V vs. RHE).

[0068] The above experiments demonstrate that the Ti3C2T prepared in Example 1... x MXene-supported copper-aluminum nano-alloy catalysts can effectively suppress hydrogen evolution side reactions, reduce the overpotential of CO2 reduction, and improve energy efficiency in electrocatalytic carbon dioxide reduction, thereby enhancing the efficiency of CO2 reduction reaction.

[0069] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A Ti3C2T x A method for preparing MXene-supported copper-aluminum nano-alloy catalysts, characterized in that, Specifically, the following steps are included: (1) First, mix hydrochloric acid and LiF, stir evenly, then add Ti3AlC2 precursor, heat in water bath, and stir magnetically to obtain dispersion A; The concentration of the hydrochloric acid is 9M; the mass-to-volume ratio of the hydrochloric acid, LiF and Ti3AlC2 precursor is 45mL:(3.6-4.0)g:2.0g; the water bath heating temperature is 45℃; the magnetic stirring speed is 450-600r / min, and the time is 48h. (2) First, wash dispersion A by centrifugation with deionized water, then by centrifugation with hydrochloric acid, and finally by washing with deionized water to obtain dispersion B. (3) Shake the dispersion B evenly, then perform ultrasonic exfoliation in an ice bath under Ar conditions, centrifuge, take the upper suspension, freeze dry, and obtain Ti3C2Tx MXene solid powder for later use; The ultrasound duration was 60 minutes; the Ti3C2T x MXene solid powder has a single-layer or single- or few-layer lamellar structure with a thickness of 1-2 nm. (4) Dissolve copper and aluminum salts in deionized water and stir magnetically to obtain a copper-aluminum salt solution; (5) Add Ti3C2T to the copper-aluminum salt solution x MXene solid powder was ultrasonicated, NaBH4 solution was added dropwise, magnetically stirred, centrifuged and washed, and then freeze-dried to obtain the Ti3C2T. x MXene-supported copper-aluminum nano-alloy catalyst.

2. A Ti3C2T according to claim 1 x A method for preparing MXene-supported copper-aluminum nano-alloy catalysts, characterized in that, In step (2), the concentration of hydrochloric acid is 1-2M; the centrifugal washing speed is 3500-10000r / min, the time is 5-15min, and the number of times is 2; the washing is carried out until the pH is 6-7.

3. A Ti3C2T according to claim 1 x A method for preparing MXene-supported copper-aluminum nano-alloy catalysts, characterized in that, In step (3), the centrifugation speed is 3500 r / min and the time is 10-60 min; the freeze-drying time is 48 h.

4. A Ti3C2T according to claim 1 x A method for preparing MXene-supported copper-aluminum nano-alloy catalysts, characterized in that, In step (4), the copper salt is copper chloride, copper nitrate trihydrate, or copper acetylacetonate; the aluminum salt is aluminum nitrate nonahydrate; the mass ratio of the copper salt to the aluminum salt is 1:1; the volume of the deionized water is 20 mL; and the magnetic stirring time is 10-30 min.

5. A Ti3C2T according to claim 1 x A method for preparing MXene-supported copper-aluminum nano-alloy catalysts, characterized in that, In step (5), the Ti3C2T x The amount of MXene solid powder added is 100-200 mg; the ultrasonication time is 30-60 min; the concentration of the NaBH4 solution is 1 M, and the amount added is 2-5 mL; the magnetic stirring time is 4 h; and the freeze-drying time is 24-48 h.

6. A Ti3C2T prepared by the preparation method according to any one of claims 1-5 x MXene-supported copper-aluminum nano-alloy catalyst.

7. A Ti3C2T prepared by the preparation method according to any one of claims 1-5 x Application of MXene-supported copper-aluminum nanoalloy catalysts in electrocatalytic carbon dioxide reduction reaction.

8. The application according to claim 7, characterized in that, Specifically, the following steps are included: (1) Ti3C2T x MXene-supported copper-aluminum nano-alloy catalyst, isopropanol, deionized water and Nafion solution were mixed evenly and ultrasonically dispersed to obtain a dispersion. (2) The dispersion was evenly dropped onto carbon paper and allowed to air dry naturally before being used as the working electrode. (3) Using a silver / silver chloride electrode as the reference electrode and a graphite rod electrode as the counter electrode, a Nafion 117 proton exchange membrane was used, and the electrolyte was a KHCO3 solution. An H-type electrolytic cell was used as the reactor, and the electrocatalytic carbon dioxide reduction reaction was carried out in an electrochemical workstation.

9. The application according to claim 8, characterized in that, In step (1), the Ti3C2T x The mass-to-volume ratio of MXene-supported copper-aluminum nano-alloy catalyst, isopropanol, deionized water, and Nafion solution was 2 mg:300 μL:100 μL:20 μL; the ultrasonic dispersion time was 30-60 min; in step (2), the carbon paper size was 1 × 1 cm. 2 The loading of the working electrode is 0.2-1.0 mg / cm³. 2 In step (3), the concentration of the KHCO3 solution is 0.1M.

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