One-pot preparation method of high-alloying gold-silver alloy aerogel material and application of high-alloying gold-silver alloy aerogel material in electrocatalytic reduction of CO2

Abstract

The invention belongs to the technical field of electro-catalysis, and particularly relates to a one-pot preparation method of a high-alloying gold-silver alloy aerogel material and application of the high-alloying gold-silver alloy aerogel material in electro-catalytic reduction of CO2. According to the preparation method, chloroauric acid and silver nitrate are selected as precursors for synthesizing the AuAg alloy aerogel, the AuAg alloy aerogel is prepared through a simple one-pot preparation method, and complex processes such as ultrafiltration centrifugal purification and concentration and heat treatment are not needed. Compared with an existing two-step method, the preparation process is complex, time and labor are consumed, and heat treatment is needed. However, according to the one-pot preparation method used in the invention, the high-alloying AuAg alloy aerogel can be obtained only by simply feeding, stirring and standing at room temperature. Moreover, the alloying degree of the obtained AuAg aerogel is higher, higher CO selectivity is shown in CO2RR application, and compared with AuAg alloy aerogel obtained through an existing two-step method, the CO Faraday efficiency of the AuAg aerogel is improved by about 37.1%.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis, and particularly relates to a one-pot preparation method of a highly alloyed gold-silver alloy aerogel material and its application in electrocatalytic reduction of CO 2 . Background Art

[0002] Electrochemically converting CO 2 into high-value fuels or chemicals is an effective way to address energy and environmental challenges. Among them, CO is a common reaction raw material in many thermochemical, biological, and electrochemical processes. It can be converted into high-value chemicals through processes such as Fischer-Tropsch synthesis or biological fermentation. CO has been considered by techno-economics to be one of the most economically valuable CO 2 conversion products. Commonly used CO alloy catalysts can affect the adsorption and activation behaviors of reactants and intermediates by adjusting the binding strength between catalytic reactants and intermediates, which is a direct method to improve the selectivity of catalysts. Various experimental and computational studies have shown that the noble metal catalysts Au and Ag have been proven to be ideal metal materials for CO 2 conversion to CO. However, due to the limitation of the linear scale relationship, simple Au and Ag single-metal electrodes are very likely unable to provide the optimal binding configurations for both *COOH and *CO simultaneously. Alloying can affect the adsorption and activation behaviors of reactants and intermediates by adjusting the molecular binding strength, enabling the catalyst to achieve the best binding with the intermediate, thereby improving the selectivity of CO. However, the high cost and scarcity of noble metals limit their large-scale application, and improving the selectivity of noble metal catalysts is beneficial for cost reduction.

[0003] Metal aerogels have a three-dimensional continuous porous network structure. The continuous conductive network skeleton structure helps with charge transfer. The high porosity and large specific surface area can fully expose the reaction active sites and increase the mass transfer rate. In the field of electrochemical energy conversion (such as reducing CO 2has potential research and application prospects. Generally, the sol-gel synthesis of metal aerogels can be achieved by one-step gelation method and two-step gelation method. Among them, the one-step gelation method is to mix one or more metal precursor salt solutions with a reducing agent, and then through static aging, the preparation of single-metal or multi-metal gels can be realized. Finally, the corresponding single-metal or multi-metal aerogels can be obtained through supercritical drying. The two-step gelation method is to first pre-synthesize a colloidal solution of metal nanoparticles, and then through centrifugal ultrafiltration concentration and purification, a mixed solution of a single-metal concentrate or a concentrate of multiple metal nanoparticles is obtained. Then, gelation is induced by adding a destabilizer or heat treatment and other destabilization treatments. Finally, through supercritical drying, the corresponding single-metal or multi-metal gels are obtained. In contrast, the one-step gelation method is simple and easy to operate, but limited by the different oxidizing properties of metal salt precursors, there is a difference in the reduction order when co-reducing different metal salt precursors, resulting in a limited variety of metal aerogels that can form metal aerogels with controllable components and better alloying of the metal aerogel skeleton. For example, PtPd metal aerogels with controllable alloying components are easily obtained, while the controllability of PtM (M is a non-noble metal) components is poor, and AuAg forms an Au@Ag core-shell structure. Although the two-step gelation method can realize the preparation of multi-metal skeleton aerogels, the diffusion and fusion ability between atoms in different metal nanoparticles is different, resulting in a large energy barrier that needs to be overcome for diffusion and fusion, resulting in different distributions of different metal elements on the aerogel skeleton due to different metal types. Some are partially alloyed (such as AuAg), some form core-shell heterostructures, and even two metals form obvious phase separation in the aerogel skeleton. Moreover, the two-step gelation method is cumbersome and costly, which is not conducive to large-scale production and preparation.

[0004] Alloyed metal catalysts can regulate the binding strength between catalytic reactants and intermediates through the synergistic effect between different metals, thereby affecting the adsorption and activation behaviors of reactants and intermediates. This is an important way to improve the performance of catalysts. However, the alloying control of multi-metal catalysts has always been extremely challenging. Traditional high-temperature annealing or high-temperature annealing treatment in the presence of a protective shell layer is cumbersome and also faces the problem of increasing the fusion size of particles during the high-temperature treatment process. It can be seen that it is of great significance to develop a simple method to prepare highly alloyed metal alloy aerogels. AuAg alloy aerogels have both the structural advantages of alloy catalysts and aerogels, and are ideal catalysts for the electrochemical conversion of CO 2 to CO. However, the Au@Ag core-shell structure metal aerogel obtained by the current one-step gelation method, and the mainstream two-step gelation method obtains a partially alloyed AuAg aerogel. The alloying degree of the product is not ideal, and the ideal CO 2 RR electrocatalytic performance cannot be obtained, and the preparation process is complex and time-consuming. Therefore, for AuAg bimetals, developing a relatively simple method for preparing alloy aerogels and realizing the regulation of their microstructure is of great significance for their application in CO 2 RR electrocatalysis. Summary of the Invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a brand-new and simple preparation method of AuAg alloy aerogel materials. The AuAg alloy aerogel materials are prepared by a simple one-pot preparation method and can be widely used in the electrocatalytic conversion reaction of CO 2 Compared with the AuAg aerogel synthesized by the two-step method, the preparation method of the present invention is simple, the obtained AuAg aerogel has a higher degree of alloying, the distribution of Au and Ag elements is more uniform, and it can promote the adsorption / activation of CO 2 molecules and the formation of *COOH intermediates, thereby greatly improving the selectivity of CO.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention provides a one-step preparation method of a gold-silver alloy aerogel material, comprising the following steps:

[0008] S1. Dissolve AgNO 3 in water, and then add NaBH 4 under stirring for reduction, so that the solution changes from colorless to yellow;

[0009] S2. Mix the yellow solution obtained in step S1 with the aqueous solution of HAuCl 4 . The solution quickly changes from yellow to black, and after stirring and standing, a black AuAg hydrogel is obtained;

[0010] S3. Perform water exchange and ethanol exchange on the hydrogel obtained in step S2 respectively, and then obtain the required aerogel after drying.

[0011] The present invention has developed a new and simple "one-pot synergistic rapid reduction method" to prepare a highly alloyed AuAg alloy aerogel. In the method of the present invention, after the pre-generated Ag nanoparticles and the simultaneous large excess of NaBH 4 synergistically reduce rapidly, when adding HAuCl 4 , the Ag nanoparticles electrochemically displace and reduce HAuCl 4 . The generated Ag + is simultaneously rapidly reduced by the large excess of NaBH 4 . Such synergistic rapid reduction promotes the alloying process of Au and Ag. Compared with the AuAg aerogel synthesized by the two-step method, it has the advantages of simpler preparation process, no need for complicated ultrafiltration, centrifugation, purification, concentration and heat treatment and other cumbersome processes, more uniform distribution of Au and Ag elements, and higher degree of alloying. The prepared highly alloyed AuAg aerogel material can promote CO 2Adsorption / activation of molecules and generation of *COOH intermediates, thus greatly improving the selectivity of CO.

[0012] Preferably, in S1, the concentration of AgNO 3 is 0.1 - 0.3 mM.

[0013] Preferably, in S2, the concentration of HAuCl 4 is 0.1 - 0.3 mM.

[0014] Preferably, the molar ratio of HAuCl 4 , AgNO 3 to NaBH 4 is 1:1:40 - 60.

[0015] Preferably, the drying is carried out by CO 2 supercritical drying method.

[0016] Preferably, in S2, stir for 20 - 500 min and then let it stand for 8 - 13 h after stirring.

[0017] Preferably, in S3, perform 7 - 10 times of water exchange and ethanol exchange on the hydrogel respectively.

[0018] The second aspect of the present invention provides a gold-silver alloy aerogel material prepared by using the one-step preparation method described in the first aspect.

[0019] The third aspect of the present invention provides the application of the gold-silver alloy aerogel material described in the second aspect in the electrocatalytic conversion of CO 2 to CO.

[0020] Preferably, the electrocatalytic conversion of CO 2 is carried out in a three-electrode system, in which the gold-silver alloy aerogel material described in the second aspect, isopropanol and 5% Nafion solution are mixed to form a catalyst ink, and then dropped onto carbon paper and dried to obtain a working electrode.

[0021] Preferably, the loading of the gold-silver alloy aerogel material in the working electrode is 1 - 3 mg / cm 2 .

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] Aiming at the problems existing in the preparation of AuAg alloy aerogels at present, the present invention adopts a novel and simple "one-pot synergistic rapid reduction method", and selects chloroauric acid (HAuCl 4 ) and silver nitrate (AgNO 3) As a precursor for synthesizing AuAg alloy aerogels, AuAg aerogels with a high degree of alloying are prepared. The AuAg alloy aerogels obtained by the relatively simple one-pot preparation method of the present invention do not require complicated processes such as ultrafiltration, centrifugation, purification, concentration, and heat treatment. In contrast, the existing two-step preparation process is complex, time-consuming, and laborious, and heat treatment is required. However, for the one-pot preparation method used in the present invention, high-alloyed AuAg alloy aerogels can be obtained only by simply feeding materials, stirring, and standing at room temperature. Moreover, the AuAg aerogels obtained in the present invention have a higher degree of alloying and exhibit higher CO selectivity in the CO 2 RR application. Compared with the AuAg alloy aerogels obtained by the existing two-step method, the CO Faraday efficiency is increased by about 37.1%. Description of the Drawings

[0024] Figure 1 Scanning electron microscope and transmission electron microscope images of the Au 50 Ag 50 -① alloy aerogel of Example 1; (a). Au 50 Ag 50 Scanning electron microscope image of the -① alloy aerogel; (b-d). Au 50 Ag 50 Transmission electron microscope images of the -① alloy aerogel at different magnifications.

[0025] Figure 2 Transmission electron microscope images of single-metal aerogels at different magnifications; (a-b). Au aerogel; (c-d). Ag aerogel.

[0026] Figure 3 Non-in-situ scanning transmission electron microscope elemental distribution maps of the gelation process of the Au 50 Ag 50 -① alloy aerogel of Example 1; (a). Before adding NaBH 4 and stirring for 1 min in Step 2, before adding HAuCl 4 ; (b). After adding HAuCl 4 and stirring for 30 s in Step 3; (c). After adding HAuCl 4 and stirring for 1 min in Step 3; (d). After adding HAuCl 4 and stirring for 30 min in Step 3; (e). After standing for 10 h after the stirring in Step 3 ends.

[0027] Figure 4 Scanning transmission electron microscope elemental distribution maps of the Au 50 Ag 50 -① alloy aerogel.

[0028] Figure 5 For Au of Comparative Example 1 50Ag 50 - ② Scanning electron microscope and transmission electron microscope images of the alloy aerogel; (a). Au 50 Ag 50 - ② Scanning electron microscope images of the alloy aerogel; (b - d). Au 50 Ag 50 - ② Transmission electron microscope images of the alloy aerogel at different magnifications.

[0029] Figure 6 For Au of Comparative Example 1 50 Ag 50 - ② Scanning transmission electron microscope elemental distribution maps of the alloy aerogel.

[0030] Figure 7 For Example 1 (Au 50 Ag 50 - ①) and Comparative Example 1 (Au 50 Ag 50 - ②), monometallic Au aerogel, monometallic Ag aerogel CO 2 RR electrochemical performance; (a). CO Faradaic efficiency FE CO ; (b). CO partial current density J CO ; (c). LSV graph; (d). Durability test. Detailed implementation manners

[0031] The following further describes the detailed implementation manners of the present invention. It should be noted here that the description of these implementation manners is for helping to understand the present invention, but does not constitute a limitation to the present invention. In addition, the technical features involved in the following various implementation manners of the present invention can be combined with each other as long as they do not conflict with each other.

[0032] The experimental methods in the following examples are all conventional methods unless otherwise specified, and the test materials used in the following examples are all commercially available through conventional channels unless otherwise specified.

[0033] Example 1: Preparation of gold - silver alloy aerogel material by using the "one - pot synergistic rapid reduction method (also called one - step method)"

[0034] Its preparation method includes the following steps:

[0035] (1) AgNO 3 Dissolution: Add 384 mL of deionized water into a 500 mL glass bottle, then add 0.04 mmol of AgNO 3 (AlfaAesar), and then stir at a speed of 500 rpm for five minutes at room temperature to ensure that AgNO 3 is completely dissolved;

[0036] (2) Reduction: Keep the AgNO 3 solution under stirring, then add 16 mL of 0.45 M NaBH 4 , and stir at a speed of 500 rpm for 1 minute for reduction, turning the solution from colorless to yellow.

[0037] (3) Hydrogel preparation: Add the yellow solution obtained in step (2) to 0.04 mmol of HAuCl 4 aqueous solution (alladdin). The solution quickly turns from yellow to black, and stir at a speed of 500 rpm for 30 minutes and then let it stand for 10 hours to obtain a black AuAg hydrogel spreading at the bottom of the bottle;

[0038] (4) Aerogel preparation: First perform 8 water exchanges on the hydrogel obtained in step (3), then perform 8 anhydrous ethanol exchanges, and then perform CO 2 supercritical drying, and the required AuAg alloy aerogel is obtained, denoted as Au 50 Ag 50 -①.

[0039] As a control, single-metal Au aerogel and single-metal Ag aerogel were prepared by the following methods respectively:

[0040] 1. Preparation of Au aerogel:

[0041] (1) Add 9.4 mL of 0.2578 M HAuCl 4 to the bottle;

[0042] (2) Add 30 mL of 0.7 M newly prepared NaBH 4 solution and stir at 500 rpm for 5 minutes to obtain a single-metal Au hydrogel;

[0043] (3) First perform 8 water exchanges, then perform 8 anhydrous ethanol exchanges, and finally perform carbon dioxide supercritical drying to obtain the required Au aerogel.

[0044] 2. Preparation of Ag aerogel:

[0045] (1) Weigh 13.6 mg of AgNO 3 , add it to 384 mL of deionized water and stir for 5 minutes;

[0046] (2) Add 30 mL of 0.7 M newly prepared NaBH 4 solution and stir at 500 rpm for 30 minutes to obtain a single-metal Ag hydrogel;

[0047] (3) First perform 8 water exchanges, then perform 8 anhydrous ethanol exchanges, and finally perform carbon dioxide supercritical drying to obtain the required Ag aerogel.

[0048] Figure 1 Scanning electron microscopy and transmission electron microscopy images of the AuAg alloy aerogel of Example 1. It can be seen from the figures that Au 50 Ag 50 -① alloy aerogel shows a significant three-dimensional porous network structure. The framework is composed of nanowires with an average size of 12.8 nm. In comparison Figure 2 it can be seen that the Au 50 Ag 50 -① alloy aerogel has a much smaller average framework size than that of single-metal Au aerogel and single-metal Ag aerogel. Figure 3 In-situ scanning transmission electron microscopy elemental distribution maps of the Au 50 Ag 50 -① alloy aerogel during the gelation process. From Figure 3 (a), it can be seen that after adding NaBH 4 for reduction in the above step (2), Ag nanoparticles were pre-generated. From Figure 3 (b), it can be seen that after adding HAuCl 4 in the above step (3), the pre-generated Ag nanoparticles and the simultaneously large amount of excessive NaBH 4 cooperatively and rapidly reduced the added HAuCl 4 . The Ag nanoparticles electrochemically displaced and substituted to reduce HAuCl 4 . Due to the stoichiometric relationship between Au and Ag, a large number of defects were generated after the electrochemical displacement substitution. From Figure 3 (c - e), it can be seen that the oxidized Ag + was simultaneously rapidly reduced by the large amount of excessive NaBH 4 . The large number of defects generated by the cooperative rapid reduction promoted the alloying process of Au and Ag. Figure 4 Scanning transmission electron microscopy elemental distribution map of the AuAg alloy aerogel of Example 1. It can be seen from it that the elemental distributions of Au and Ag are relatively uniform and the degree of alloying is high.

[0049] Comparative Example 1: Preparation of AuAg alloy aerogel by a traditional two-step method

[0050] The preparation method includes the following steps:

[0051] (1) Preparation of Au NPs: Add 0.14 mmol of HAuCl 4 to 500 mL of deionized water. After stirring for 10 minutes, add 11.6 mL of 1% sodium citrate solution and stir for 1 minute. Then add 5.8 mL of an ice-water mixture of freshly prepared NaBH 4 and sodium citrate (containing 9.7 mg of NaBH 4 and 5.8 mg of sodium citrate), and stir for 30 minutes.

[0052] (2) Preparation of Ag NPs: Heat 500 mL of deionized water to boiling, add 0.14 mmol of AgNO 3 to it, stir for 10 minutes, then add 11.6 mL of 1% sodium citrate solution, stir for 1 minute, and then add 5.8 mL of a freshly prepared ice-water mixture of NaBH 4 and sodium citrate (containing 4.2 mg of NaBH 4 and 5.5 mg of sodium citrate), and stir for 10 minutes.

[0053] (3) Purification and concentration of NPs solution: Purify and concentrate the NPs solutions synthesized in steps (2) and (3) respectively using ultrafiltration centrifugal tubes with a MWCO of 3000. Specifically: Concentrate 500 mL of each NPs solution into a concentrated solution of about 5 mL, then add 120 mL of deionized water and centrifuge again. Repeat this operation 6 times to wash away the stabilizer sodium citrate in the solution. Finally, obtain 5 mL of concentrated Au NPs solution and 5 mL of concentrated Ag NPs solution respectively. After light-shielding treatment, store them in the refrigerator overnight;

[0054] (4) Preparation of hydrogel: Take 1 mL of each purified Au NPs solution and Ag NPs solution, shake and mix them evenly, then place them in an oven at 75 °C for 6 hours to obtain the corresponding hydrogel;

[0055] (5) Preparation of aerogel: First perform 8 water exchanges on the hydrogel obtained in step (4), then perform 8 anhydrous ethanol exchanges, and then perform CO 2 supercritical drying, and the required AuAg alloy aerogel is obtained, denoted as Au 50 Ag 50 -②.

[0056] Figure 5 For the scanning electron microscope image and transmission electron microscope image of the Au 50 Ag 50 -① alloy aerogel of Comparative Example 1, it can be seen from the figure that the Au 50 Ag 50 -② alloy aerogel shows a significant three-dimensional porous network structure. The Au 50 Ag 50 -② alloy aerogel nano-framework is composed of nanowires, with an average size of 10.2 nm, which is also smaller than that of single-metal Au aerogel and single-metal Ag aerogel. Figure 6 For Control Group 1 Au 50 Ag 50-②Element distribution map of the alloy aerogel by scanning transmission electron microscopy. It can be seen from the results that there is microphase separation in the element distribution of Au and Ag, and the degree of alloying is not high. It can be seen that the catalyst obtained in Comparative Example 1 has the same three-dimensional porous structure as that in Example 1, and there is no obvious difference in the scanning electron microscopy and transmission electron microscopy images. However, there is microphase separation in the element distribution of Au and Ag, and the degree of alloying is not high.

[0057] Experimental example: Electrochemical reduction of CO by AuAg alloy aerogel 2 Application

[0058] (1) Ink preparation: Mix 20 mg of catalyst (monometallic Au aerogel, monometallic Ag aerogel, Au 50 Ag 50 -① alloy aerogel or Au 50 Ag 50 -② alloy aerogel), 960 μL of isopropanol, and 40 μL of 5% Nafion solution, and ultrasonically mix for 1 h below 20 °C to obtain the corresponding catalyst ink;

[0059] (2) Electrode preparation: Drop 100 μL of the catalyst ink onto a 1×1 cm 2 carbon paper (Toray TGP-H060, PTFE 20%), and naturally dry overnight at room temperature to obtain a working electrode with a loading of 1 mg / cm 2 ;

[0060] (3) Before starting the test, continuously introduce Ar and CO 2 into the cathode chamber electrolyte for 30 min each to expel the remaining air in the electrolytic cell and make the electrolyte in a CO 2 -saturated state; 2

[0061] (4) Use an Auto Lab electrochemical workstation to conduct tests at room temperature and atmospheric pressure. Measure LSV in the atmosphere of Ar and CO 2 to preliminarily evaluate the catalytic performance of the catalyst for the CO 2 catalytic conversion reaction. Use the double-capacitance method to estimate the electrochemically active surface area of the electrode, calculate the CO Faraday efficiency FE CO , the partial current density J CO of CO, and conduct a durability test to evaluate the stability of the catalyst.

[0062] During the test, a standard three-electrode H-type electrolytic cell is used, and the electrolyte is 0.1 M KHCO 3(pH = 6.8), the two chambers of the electrolytic cell are separated by an N117 proton exchange membrane. Ag / AgCl (saturated KCl solution) and a Pt sheet are used as the reference electrode and the counter electrode respectively. Linear sweep voltammetry is adopted, and the test voltage range is -0.5 V to -0.9 V vs. RHE, with a scan rate of 50 mV / s.

[0063] (5) Test results:

[0064] From Figure 7 it can be seen that when the Au 50 Ag 50 -① alloy aerogel of Example 1 is applied to the electrocatalytic reduction of CO 2 , it exhibits excellent CO selectivity and activity. Among them, at a voltage of -0.7 V vs. RHE, FE CO reaches 97.8%, and J CO is 4.7 mA / cm 2 . At the same potential, the FE 50 of the single-metal Au aerogel, the single-metal Ag aerogel, and the Au 50 Ag CO -② alloy aerogel of Comparative Example 1 are 93.5%, 46.2%, and 60.7% respectively, and the J CO are 4.3 mA / cm 2 , 0.2 mA / cm 2 and 3.6 mA / cm 2 respectively. It can be seen that at a relatively low overpotential (-0.7 V vs. RHE), the CO selectivity and activity of the Au 50 Ag 50 -① alloy aerogel are significantly improved compared to the Au 50 Ag 50 -② alloy aerogel. It should be noted that when the Au content of Au 50 Ag 50 -① decreases by 50%, its performance still exceeds that of the single-metal Au aerogel, indicating that the alloying strategy effectively improves the utilization rate of precious metals. At a voltage of -0.7 V vs. RHE, the Au 50 Ag 50 -① and the Au 50 Ag 50 -② are subjected to a durability test. After 18 hours of constant potential electrolysis, the FE 50 of Au 50 Ag CO -① drops from 97.8% to 87.3%, only decreasing by 10.7%, indicating that it has good stability. After the durability test of Au 50 Ag 50 -②, the FE COThe change is not significant and the stability is also good. The purpose here is to study the effect of the alloying degree on the electrocatalytic reduction performance of gold-silver alloy aerogels for carbon dioxide, so no further durability tests were carried out on single-metal aerogels.

[0065] In summary, the AuAg aerogel catalytic material prepared by the two-step method, Au 50 Ag 50 -② electroreduction of CO 2 The CO Faraday efficiency at -0.7 V vs. RHE potential is only 60.7%, compared with the AuAg aerogel catalytic material Au 50 Ag 50 -① prepared by the one-pot method in Example 1, the CO selectivity is 37.1% lower. It is speculated that the increase in the alloying degree can improve the selectivity of electroreduction of CO 2 converted to CO. It can be seen that compared with the two-step method, the Au 50 Ag 50 -① alloy aerogel material obtained by the simple one-pot preparation method of the present invention has the advantages of simpler preparation process, no need for complicated ultrafiltration, centrifugation, purification, concentration and heat treatment and other cumbersome processes, more uniform distribution of Au and Ag elements, and higher alloying degree. It has been found through research that this high-alloying Au 50 Ag 50 -① aerogel material can promote the adsorption / activation of CO 2 molecules and the formation of *COOH intermediates, thereby improving the selectivity of CO.

[0066] The above has described the embodiments of the present invention in detail, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions and variations of these embodiments still fall within the protection scope of the present invention.

Claims

1. A one-step preparation method of a gold-silver alloy aerogel material, characterized in that: The following steps are involved: S1. Dissolve AgNO3 in water, then add NaBH4 under stirring to reduce the solution, so that the solution changes from colorless to yellow; S2, mixing the yellow solution obtained in step S1 with the HAuCl4 aqueous solution, the solution quickly changes from yellow to black, and then after stirring and standing, a black AuAg hydrogel is obtained; S3, exchanging water and ethanol respectively on the hydrogel obtained in step S2, and then drying to obtain the desired aerogel.

2. The one-step preparation method of a gold-silver alloy aerogel material according to claim 1, characterized in that: In S1, the concentration of AgNO3 is 0.1-0.3 mM.

3. The one-step preparation method of a gold-silver alloy aerogel material according to claim 1, characterized in that: In S2, the concentration of HAuCl4 was 0.1-0.3 mM.

4. The one-step preparation method of a gold-silver alloy aerogel material according to claim 1, characterized in that: The molar ratio of HAuCl4, AgNO3 and NaBH4 is: 1:1:40-60.

5. The one-step preparation method of a gold-silver alloy aerogel material according to claim 1, characterized in that: The drying adopts CO2 supercritical drying method.

6. The one-step preparation method of a gold-silver alloy aerogel material according to claim 1, characterized in that: In S2, stir for 20-500 min, and then let stand for 8-13 h.

7. The one-step preparation method of a gold-silver alloy aerogel material according to claim 1, characterized in that: In S3, the hydrogel was subjected to 7-10 water exchanges and ethanol exchanges, respectively.

8. The gold-silver alloy aerogel material prepared by the one-step preparation method according to claim 7.

9. Use of the gold-silver alloy aerogel material according to claim 8 in the electrocatalytic conversion of CO2 into CO.

10. The use according to claim 9, characterized in that: The CO2 electrocatalytic conversion is carried out in a three-electrode system, wherein the gold-silver alloy aerogel material according to claim 8, isopropanol and 5% Nafion solution are mixed to form catalyst ink, which is then dropped onto carbon paper and dried to obtain a working electrode.

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