Porous material based on liquid metal, and preparation method therefor and use thereof

Abstract

A porous material based on a liquid metal, and a preparation method therefor and the use thereof. The porous material is obtained by mixing a liquid metal, which is obtained by heating and liquefying a metal, an organic solvent, a surfactant and copper foam, and then reacting same.

Description

Liquid metal-based porous material and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of electrocatalysts, and in particular to a liquid metal-based porous material and a preparation method and application thereof. Background Art

[0002] Over the past few decades, global energy demand has been rising rapidly due to rapid population and economic growth. Ammonia, with its high hydrogen content and high gravimetric energy density, is one of the greenest and most promising energy carriers available for technical operation. It is also one of the world's most abundant and important chemicals. Over 150 million tons of ammonia are produced annually via the Haber-Bosch process, which has found widespread application in synthetic fertilizers, textiles, and the pharmaceutical industry. Over 80% of this is used in fertilizers, meeting the energy needs of half the world's population. However, this process requires high temperatures and pressures (100-300 atm, 300-500°C) and is extremely dependent on fossil fuels, accounting for 1-2% of global energy consumption and approximately 1% of global greenhouse gas emissions annually. Therefore, exploring environmentally friendly, sustainable, and efficient alternative methods for ammonia synthesis is crucial.

[0003] The catalytic conversion of nitrogen into valuable chemicals and low-carbon fuels is an important scientific and technological issue. However, the practical application of electrochemical nitrogen reduction has not yet been fully realized, mainly due to the lack of high-performance electrocatalysts, which play a decisive role in electrochemical nitrogen reduction. In this regard, many studies on the development of electrocatalysts have been reported in the past few decades. In recent years, with the rapid development of the design and synthesis of new materials, people have become increasingly interested in the study of nitrogen. Among all the electrocatalysts explored and developed for nitrogen, transition metal and P-block metal-related catalysts have attracted increasing attention and shown potential to catalyze the electroconversion of nitrogen into useful fuels / chemicals.

[0004] The morphology of the catalyst is a key factor in determining the performance of the catalyst at different length scales, from the nanoscale (surface, grain boundaries, edges, corners, surface deformation) to the microscale (local N2 concentration, adsorption / desorption, wettability and transport of reactants and products, etc.). Studies have shown that the unoccupied d orbitals of transition metals can relieve the kinetic barriers to N2 activation through the following "π feedback" behavior: Ga is also theoretically predicted to be a promising candidate for highly selective NRR, Ga adopts sp in the outer orbital 3Hybridization leaves an empty orbital (in addition to the three occupied orbitals) to mimic "π-feedback" behavior, so its NRR activity is expected to be higher, but it has not been experimentally demonstrated. Given the unique but complementary electronic structures of transition metals and p-block metals, combining them to achieve highly active and selective N2 electroreduction remains complex and challenging. Therefore, more efforts should be made to find green and economical preparation methods for Ga-based nanoelectrocatalysts with high N2 to NH3 conversion efficiency.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to provide a liquid metal-based porous material and a preparation method and application thereof to solve the problems existing in the prior art.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a preparation method based on liquid metal porous material, comprising the following steps:

[0009] Liquid metal obtained by heating and liquefying the metal, an organic solvent, a surfactant and foamed copper are mixed and reacted to obtain a porous material.

[0010] Preferably, the metal contains Ga, and the temperature for heating and liquefaction is 30-50°C.

[0011] Preferably, the organic solvent comprises ethylene glycol or ethanol; the surfactant comprises hexadecyltrimethylammonium bromide, sodium hexadecylsulfonate or sodium lauryl sulfate; and the volume of the copper foam is 0.4 cm×0.4 cm×0.1 cm to 0.6 cm×0.6 cm×0.3 cm.

[0012] Preferably, the ratio of the liquid metal to the organic solvent is 0.5-2 g: 3-10 mL.

[0013] Preferably, the ratio of the liquid metal to the foamed copper is 0.5-2 g: 1-5 pieces.

[0014] Preferably, the usage ratio of the surfactant to the organic solvent is 0.0552 g: 3-10 mL.

[0015] Preferably, the reaction conditions are ultrasonication at room temperature, the ultrasonication time is 10 to 15 minutes, and the power is 20 to 50% AMPL.

[0016] Preferably, after the reaction is completed, ultrasonication, washing and drying are performed to obtain a porous material;

[0017] The ultrasonic time is 10 to 15 minutes, and the power is 20 to 50% AMPL; the washing is performed by alternating water and anhydrous ethanol for 3 to 5 times; the drying temperature is 50 to 80° C., and the drying time is 5 to 12 hours.

[0018] The present invention also provides a porous material prepared by the above preparation method.

[0019] The present invention also provides the use of the porous material in electrocatalytic N2 reduction.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention adopts bubble template method to promote the load of dispersed droplet Ga on foam copper and regulate its morphology, by using probe ultrasonic auxiliary surfactant and polar organic solvent to produce bubbles at room temperature, and then make liquid metal gallium disperse and can be more completely loaded on foam copper, synthesize the porous material of electrocatalytic nitrogen reduction, and can directly use the porous material as high-performance electrocatalytic reduction N2 material. In the material synthesis process, the process used is simple and safe (only room temperature synthesis, ultrasonic auxiliary, does not involve vacuum, special calcining atmosphere and other complex environments), the instrument is simple (main instrument is beaker, probe ultrasonic machine, centrifuge), and the cycle is short, the output is large, the process operation is simple, the product performance is stable, the material structure is uniform, the catalytic performance is good and is not easy to cause secondary pollution. Thus it has broader scientific research and practical value, and is expected to be widely used in the research and production of new catalyst materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG1 is an X-ray powder diffraction spectrum of the Foam-CuGa material prepared in Example 1;

[0023] FIG2 is a scanning electron microscope image of the Foam-CuGa material prepared in Example 1;

[0024] FIG3 is an X-ray powder diffraction spectrum of the Foam-Cu material prepared in Comparative Example 1;

[0025] FIG4 is a scanning electron microscope image of the Foam-Cu material prepared in Comparative Example 1;

[0026] FIG5 is a current density diagram of the Foam-CuGa material prepared in Example 1 under different atmospheres (Ar, N2);

[0027] FIG6 is a current density diagram of NH3, the main product of electrocatalytic N2 reduction, of Foam-Cu, Foam-CuGa, and 0.5gFoam-CuGa materials;

[0028] FIG7 is a Faradaic efficiency diagram of the reduction products of Foam-Cu, Foam-CuGa, and 0.5 g Foam-CuGa materials in electrocatalytic N2 reduction;

[0029] Figure 8 shows the yield of NH3, the main product, in the electrocatalytic N2 reduction of Foam-Cu, Foam-CuGa, and 0.5gFoam-CuGa materials. DETAILED DESCRIPTION

[0030] The present invention provides a preparation method based on liquid metal porous material, comprising the following steps:

[0031] Liquid metal obtained by heating and liquefying the metal, an organic solvent, a surfactant and foamed copper are mixed and reacted to obtain a porous material.

[0032] In the present invention, the metal contains Ga, and the heating and liquefaction temperature is 30 to 50°C, preferably 32 to 48°C, more preferably 35 to 45°C, and even more preferably 40°C.

[0033] In the present invention, the organic solvent comprises ethylene glycol or ethanol, preferably ethylene glycol; the surfactant comprises cetyltrimethylammonium bromide, sodium cetyl sulfonate or sodium lauryl sulfate, preferably cetyltrimethylammonium bromide or sodium cetyl sulfonate, more preferably cetyltrimethylammonium bromide; the volume of the copper foam is 0.4 cm×0.4 cm×0.1 cm to 0.6 cm×0.6 cm×0.3 cm, preferably 0.45 cm×0.45 cm×0.15 cm to 0.55 cm×0.55 cm×0.25 cm, more preferably 0.5 cm×0.5 cm×0.2 cm.

[0034] In the present invention, the ratio of the liquid metal to the organic solvent is 0.5-2 g: 3-10 mL, preferably 1-1.8 g: 4-9 mL, more preferably 1.2-1.6 g: 5-8 mL, and even more preferably 1.4-1.5 g: 6-7 mL.

[0035] In the present invention, the ratio of the liquid metal to the foamed copper is 0.5-2 g: 1-5 pieces, preferably 0.8-1.6 g: 2-4 pieces, and more preferably 1.2-1.4 g: 3 pieces.

[0036] In the present invention, the usage ratio of the surfactant to the organic solvent is 0.0552 g: 3-10 mL, preferably 0.0552 g: 4-9 mL, more preferably 0.0552 g: 5-8 mL, and even more preferably 0.0552 g: 6-7 mL.

[0037] In the present invention, the reaction conditions are ultrasonication at room temperature, the ultrasonication time is 10 to 15 minutes, preferably 11 to 14 minutes, more preferably 12 to 13 minutes, the power is 20 to 50% AMPL, preferably 25 to 45% AMPL, more preferably 30 to 40% AMPL, and even more preferably 35 to 38% AMPL.

[0038] In the present invention, after the reaction is completed, ultrasonic removal of excess liquid on the surface of the foam copper is performed, followed by washing and drying to obtain a porous material;

[0039] The ultrasonic time is 10 to 15 minutes, preferably 11 to 14 minutes, more preferably 12 to 13 minutes; the power is 20 to 50% AMPL, preferably 25 to 45% AMPL, more preferably 30 to 40% AMPL, and even more preferably 35 to 38% AMPL;

[0040] The washing is performed by alternating water and anhydrous ethanol for 3 to 5 times, preferably 4 times;

[0041] The drying temperature is 50-80°C, preferably 55-75°C, more preferably 60-72°C, and even more preferably 65-70°C; the drying time is 5-12h, preferably 5.5-10h, more preferably 6-9h, and even more preferably 7-8h.

[0042] The present invention also provides a porous material prepared by the above preparation method.

[0043] The present invention also provides the use of the porous material in electrocatalytic N2 reduction.

[0044] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0045] Example 1

[0046] At 25°C, 1.2g of Ga was weighed and placed in a clean beaker. The mixture was heated to 40°C, and 3mL of ethylene glycol was added. After the solid Ga completely melted into droplets, the ethylene glycol was added. Three cleaned 5cm×5cm×2cm pieces of copper foam and 0.0552g of hexadecyltrimethylammonium bromide were then added. After stirring, the mixture was ultrasonicated for 10 minutes at 30% AMPL. After the reaction was complete, the product was ultrasonically rinsed at 30% AMPL for 10 minutes, then rinsed five times alternately with deionized water and anhydrous ethanol, and finally dried in a 60°C oven for 12 hours to obtain the Foam-CuGa porous material.

[0047] FIG1 shows the characteristic diffraction peaks of the X-ray powder diffraction spectrum of the prepared Foam-CuGa material, indicating the successful synthesis of the Ga-doped porous material.

[0048] FIG2 is a scanning electron microscope photograph of the prepared Foam-CuGa material, showing that the material exhibits a mesh coating morphology.

[0049] Example 2

[0050] At 25°C, 0.5g of Ga was weighed and placed in a clean beaker. The mixture was heated to 40°C, and 3mL of ethylene glycol was added. After the solid Ga completely melted into droplets, the ethylene glycol was added. Three cleaned foam copper pieces measuring 5cm x 5cm x 2cm and 0.0552g of hexadecyltrimethylammonium bromide were then added. After stirring, the mixture was ultrasonicated for 10 minutes at 30% AMPL. After the reaction was complete, the product was ultrasonically rinsed at 30% AMPL for 10 minutes, then rinsed five times alternately with deionized water and anhydrous ethanol, and finally dried in a 60°C oven for 12 hours, yielding 0.5g of the porous CuGa foam material.

[0051] Comparative Example 1 (no liquid metal Ga added)

[0052] Acetone, 0.1 mol / L dilute hydrochloric acid, and anhydrous ethanol were used to clean 0.5 cm×0.5 cm copper foam at an ultrasonic power of 30% AMPL for 10 min, and then dried in an oven at 60°C for 12 h to finally obtain Foam-Cu material.

[0053] FIG3 is a characteristic diffraction peak of an X-ray powder diffraction spectrum of the prepared Foam-Cu material, which is shown as a characteristic diffraction peak of Foam-Cu.

[0054] FIG4 is a scanning electron microscope photograph of the prepared Foam-Cu material, showing that the material has a hexagonal prism morphology.

[0055] Comparative Example 2 (no surfactant added)

[0056] At 25°C, 1.2g of Ga was weighed and placed in a clean beaker. The mixture was heated to 40°C, and 3mL of ethylene glycol was added. After the solid Ga completely melted into droplets, the ethylene glycol was added. Three cleaned copper foam pieces measuring 5cm x 5cm x 2cm were then added. After stirring, the mixture was ultrasonicated for 10 minutes at 30% AMPL. After the reaction was complete, the product was ultrasonically cleaned for 10 minutes at 30% AMPL and then dried in a 60°C oven for 12 hours to obtain the Foam-CuGa material. However, the surface loading layer of the copper foam was incomplete or absent after the reaction, making it impossible to synthesize a Ga-loaded porous material.

[0057] Application Example 1

[0058] Electrochemical N2 reduction tests of the Foam-CuGa prepared in Example 1, 0.5 g of Foam-CuGa prepared in Example 2, and the Foam-Cu prepared in Comparative Example 1 were conducted on a standard dual-chamber three-electrode system connected to an electrochemical workstation (CHI 660E). A 0.1 M KOH solution was used as the electrolyte, the prepared Foam-CuGa / 0.5 g of Foam-CuGa / Foam-Cu solution was used as the working electrode, a platinum sheet was used as the counter electrode, and Hg / HgO was used as the reference electrode. The liquid phase product was measured in real time using a UV-Vis-NIR spectrophotometer. Electrochemical N2 reduction tests were conducted in this system.

[0059] Figure 5 is a current density diagram of the Foam-CuGa material prepared in Example 1 under different atmospheres (N2, Ar). It can be seen from the current density diagram that the Foam-CuGa prepared by doping with liquid metal Ga exhibits a larger current density under N2 atmosphere, proving that the prepared material has N2 reduction activity.

[0060] Figure 6 is a current density diagram of NH3, the main product of electrocatalytic N2 reduction, of Foam-CuGa prepared in Example 1, 0.5 g Foam-CuGa prepared in Example 2, and Foam-Cu prepared in Comparative Example 1. It can be seen from the figure that the current density of NH3 in the electrocatalytic N2 reduction using the porous material (Foam-CuGa) prepared by doping Ga as a catalyst is significantly higher than that of the porous material (Foam-Cu) prepared without doping Ga.

[0061] FIG7 is a Faraday efficiency diagram of the reduction products of Foam-CuGa prepared in Example 1, 0.5 g Foam-CuGa prepared in Example 2, and Foam-Cu prepared in Comparative Example 1. By comparison, it can be seen that the reduction products of Foam-CuGa prepared in Example 1 are -0.1 to -0.3. VRHE The main product NH3 of Foam-CuGa prepared by adding liquid metal Ga is -0.1VRHE The Faraday efficiency can reach nearly 40%, which is significantly improved compared to the 10% of Foam-Cu prepared without doping with liquid metal Ga.

[0062] FIG8 is a graph showing the yield of NH3, the main product of electrocatalytic N2 reduction, of Foam-CuGa prepared in Example 1, 0.5 g Foam-CuGa prepared in Example 2, and Foam-Cu prepared in Comparative Example 1. As can be seen from the figure, the porous material (Foam-CuGa) prepared by incorporating liquid metal Ga as a catalyst can achieve an NH3 yield of 14.6 μg·cm -2 ·h -1 (-0.3 VRHE ), which is significantly higher than the 0.64 μg·cm of Foam-Cu prepared without liquid metal Ga. -2 ·h -1 (-0.3 VRHE ).

[0063] As can be seen from the above examples, the present invention provides a liquid metal-based porous material, its preparation method, and its application. By using a surfactant and a polar organic solvent to generate bubbles, the present invention disperses liquid metal gallium at room temperature, enabling it to be more completely loaded onto copper foam. This results in a porous material that electrocatalyzes nitrogen reduction. The synthesis cycle is short, making it suitable for large-scale production. The resulting material has a uniform structure and excellent catalytic performance, significantly improving the catalytic performance of Foam-Cu prepared without liquid metal Ga.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A preparation method based on liquid metal porous material, characterized in that: The following steps are involved: Liquid metal obtained by heating and liquefying the metal, an organic solvent, a surfactant and foamed copper are mixed and reacted to obtain a porous material.

2. A preparation method based on liquid metal porous material according to claim 1, characterized in that: The metal includes Ga, and the heating and liquefaction temperature is 30 to 50°C.

3. A preparation method based on liquid metal porous material according to claim 2, characterized in that: The organic solvent comprises ethylene glycol or ethanol; the surfactant comprises hexadecyltrimethylammonium bromide, sodium hexadecyl sulfonate or sodium dodecyl sulfate; and the volume of the foam copper is 0.4 cm×0.4 cm×0.1 cm to 0.6 cm×0.6 cm×0.3 cm.

4. A method for preparing a porous material based on liquid metal according to any one of claims 1 to 3, characterized in that: The usage ratio of the liquid metal to the organic solvent is 0.5-2 g: 3-10 mL.

5. The method for preparing a porous material based on liquid metal according to claim 4, characterized in that: The usage ratio of the liquid metal to the foam copper is 0.5-2 g: 1-5 pieces.

6. A method for preparing a porous material based on liquid metal according to claim 3 or 5, characterized in that: The usage ratio of the surfactant and the organic solvent is 0.0552 g: 3-10 mL.

7. A method for preparing a porous material based on liquid metal according to claim 6, characterized in that: The reaction conditions are as follows: ultrasonication is performed at room temperature, the ultrasonication time is 10 to 15 minutes, and the power is 20 to 50% AMPL.

8. A method for preparing a porous material based on liquid metal according to claim 1, 2, 3, 5 or 7, characterized in that: After the reaction is completed, ultrasonication, washing and drying are performed to obtain a porous material; The ultrasonic time is 10-15 minutes, and the power is 20-50% AMPL; the washing is 3-5 times of alternating water and anhydrous ethanol; the drying temperature is 50-80° C., and the drying time is 5-12 hours.

9. The porous material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the porous material according to claim 9 in electrocatalytic N2 reduction.

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