Silicon carbide-loaded Ag30Cu14 nanocluster catalyst and application thereof in electrocatalytic CO2 reduction

Abstract

The invention relates to the technical field of electrochemical catalysis and carbon dioxide conversion, in particular to a silicon carbide loaded Ag30Cu14 nanocluster catalyst and application thereof in electrocatalytic CO2 reduction. The silicon carbide loaded Ag30Cu14 nanocluster catalyst is an Ag30Cu14 bimetallic nanocluster with precise atoms, the chemical formula is Ag30Cu14 (TPP) 4 (SR) 28, the silicon carbide loaded Ag30Cu14 nanocluster catalyst has an irregular structure of an Ag27 core and an Ag3Cu14 shell, and the silicon carbide is loaded with the Ag30Cu14 nanocluster; the silicon carbide-loaded Ag30Cu14 nanocluster catalyst prepared by the preparation method disclosed by the invention is a loaded CO2RR catalyst which is low in cost and accurate in atom structure, and the product selectivity can be regulated and controlled through post-treatment.

Description

Technical Field

[0001] This invention relates to the field of electrochemical catalysis and carbon dioxide conversion technology, specifically to silicon carbide-supported Ag. 30 Cu 14 Nanocluster catalysts and their application in electrocatalytic CO2 reduction. Background Technology

[0002] With the extensive use of fossil fuels (coal, oil, and natural gas), atmospheric CO2 levels have continued to rise, causing serious environmental problems such as global warming. Meanwhile, CO2 is an abundant carbon resource, and converting it into high-value chemicals or fuels (such as CO, CH4, and C2H4) is crucial for achieving the carbon cycle.

[0003] CO2 molecules are thermodynamically stable and kinetically inert, making their activation and reduction extremely challenging. Electrocatalytic CO2 reduction (hereinafter referred to as CO2RR) is considered an important strategy in the field of sustainable energy because it can be driven by renewable energy electricity under mild conditions. Catalysts are the core of CO2RR. Existing catalysts mainly include metal catalysts (Cu, Ag, Au), alloy catalysts, transition metal compounds, and organic catalysts. In addition, nanostructured catalysts (such as nanoclusters), surface-modified catalysts, and functionalized carbon materials have also been extensively studied.

[0004] However, existing technologies have the following shortcomings: 1) Au-based nanoclusters are expensive, Ag and Cu-based nanoclusters have moderate stability and product selectivity are difficult to control, and there is a lack of atomically accurate model systems, which limits the study of catalytic mechanisms; 2) Supports mostly only serve as loading agents and cannot actively regulate the cluster structure to generate specific active sites; 3) CO2RR product selectivity is difficult to regulate, and most catalysts can only efficiently generate a single product, making it difficult to achieve product switching through simple post-processing.

[0005] Therefore, developing a low-cost, atomically precise supported CO2RR catalyst with product selectivity that can be controlled through post-processing has become an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the aforementioned issues, this application provides silicon carbide-supported Ag... 30 Cu 14 Nanocluster catalysts and their application in electrocatalytic CO2 reduction: This catalyst is a low-cost, atomically precise, and product-selective supported CO2RR catalyst that can be controlled through post-processing.

[0007] To achieve the above objectives, this application provides silicon carbide-supported Ag 30 Cu 14 Nanocluster catalyst, the catalyst is an atomically precise Ag30 Cu 14 Bimetallic nanoclusters with the chemical formula Ag 30 Cu 14 (TPP)4(SR) 28 (where TPP is triphenylphosphine and SR is 3-methylbenzenethiol), having an irregular "Ag 27 core + Ag3Cu 14 shell" structure, and is composed of silver and copper nanoclusters supported by silicon carbide (SiC). 30 Cu 14 nanoclusters.

[0008] The preparation method of the silicon carbide-supported Ag 30 Cu 14 nanocluster catalyst includes the following steps: S1. Dissolve silver nitrate and triphenylphosphine in absolute ethanol, stir, add 3-methylbenzenethiol and copper chloride, react for 10 - 15 minutes, centrifuge for 3 - 5 minutes, remove the supernatant, and collect the precipitate; S2. Disperse the precipitate in an absolute ethanol-dichloromethane mixed solution, then add a NaBH4 ethanol solution, stir for 5 - 6 hours, then centrifuge to collect the Ag 30 Cu 14 (TPP)4(SR) 28 precipitate, dissolve the precipitate in dichloromethane, then diffuse n-hexane into the dichloromethane solution for one week to obtain the cluster Ag 30 Cu 14 ; S3. Dissolve the cluster Ag 30 Cu 14 in dichloromethane (the mass-volume ratio of the cluster to dichloromethane is 1:25), add silicon carbide (commercially purchased β-SiC powder with an average particle size of 50 nm, specific surface area of 35 m² / g, pickled with 1 mol / L HCl for 2 hours and vacuum dried before use), the mass ratio of the cluster to silicon carbide is 1:10 (loading amount is 9.1 wt%), perform ultrasonic treatment, then seal and rotary evaporate for 50 - 60 min, collect the solid, and determine the Ag and Cu element contents by ICP-MS to obtain the silicon carbide-supported Ag 30 Cu 14 nanocluster <span catalyst.

[0009] Furthermore, the molar ratio of silver nitrate, triphenylphosphine, 3-methylbenzenethiol, and copper chloride is 15 - 20:20 - 25:40 - 45:23 - 27, where the molar ratio of 3-methylbenzenethiol (SR) to metal atoms (Ag + Cu) is 1.2:1, and the excess ligand can effectively inhibit the aggregation of the clusters and stabilize the Ag 30 Cu 14 core-shell structure.

[0010] Furthermore, the stirring described in step S1 is performed at a speed of 80-100 rpm for 10-15 minutes.

[0011] Furthermore, the centrifugation in step S1 is performed at a speed of 7000-8000 rpm.

[0012] Furthermore, the concentration of the NaBH4 ethanol solution is 0.2-0.6 mol / L.

[0013] Furthermore, in step S2, the centrifugation speed is 9000-10000 rpm, and the time is 3-5 minutes.

[0014] Furthermore, the precipitate is dissolved in dichloromethane at a mass-to-volume ratio of 1:20-30.

[0015] Furthermore, the ultrasonic treatment is performed at a frequency of 20-50kHz, with an ultrasonic power of 100-400W, for a duration of 10-20 minutes.

[0016] Furthermore, the rotary evaporation is carried out at a temperature of 25-35°C, a vacuum degree of 0.08-0.1 MPa, and a rotation speed of 100-150 rpm.

[0017] This application provides silicon carbide-supported Ag 30 Cu 14 The method for reducing nanocluster catalysts includes the following steps: taking 20 mg of silicon carbide-supported Ag 30 Cu 14 Nanoclusters were added to 20 mL of 0.4 mol / L NaBH4 solution and sonicated (ultrasonic frequency 35 kHz, ultrasonic power 200 W) for 1 hour. Then, the mixture was centrifuged at 8000 rpm for 3 minutes, the supernatant was removed, and the precipitate was collected. The precipitate was washed three times with deionized water and once with anhydrous ethanol, and dried at 60 °C for 12 hours. This process was repeated four times to obtain reduced silicon carbide-loaded Ag. 30 Cu 14 Nanocluster catalysts.

[0018] This application also provides silicon carbide-supported Ag. 30 Cu 14 The application of nanocluster catalysts in electrocatalytic CO2 reduction includes the following steps: Weigh 5.0 mg of silicon carbide-supported Ag. 30 Cu 14 Nanocluster catalysts or Ag supported on reduced silicon carbide 30 Cu 14The nanocluster catalyst was placed in a test tube, and 500 μL of anhydrous ethanol and 20 μL of Nafion solution were added to the test tube respectively. The mixture was ultrasonically dispersed for 1 h to form a homogeneous slurry. Then, 300 μL of the slurry was transferred by pipette and dropped onto the surface of a carbon paper with a diameter of 1.0 cm × 3.0 cm. After air drying, it served as the working electrode. 1 M KHCO3 was used as the electrolyte. The side of the carbon paper with the catalyst loaded was in contact with the electrolyte, while the side without the catalyst loaded was connected to the gas chamber. The CO2 flow rate was 20 mL / min. Ag / AgCl was used as the reference electrode, and a platinum sheet was used as the counter electrode. All potentials were calibrated to the reversible hydrogen electrode based on the reference electrode. The calibration formula was: E(RHE) = E(Ag / AgCl) + 0.0592 × pH + 0.197. Before electrochemical testing, CO2 was first introduced into the electrolytic cell through the working electrode until the flow rate stabilized. The test conditions were -0.8 V to -1.7 V vs. The long-range stability of the sample was tested by cyclic voltammetry (CV) at 20 mV / s for 10 cycles under RHE conditions, and linear sweep voltammetry (LSV) at 20 mV / s with a test window of -0.8 V to -1.7 V (V vs. RHE).

[0019] In summary, this application has the following beneficial effects: Product selectivity is controllable: Unreduced silicon carbide supported on Ag 30 Cu 14 Nanocluster catalysts exhibit high selectivity for CO and high Faraday efficiency; reduced silicon carbide supported on Ag 30 Cu 14 Nanocluster catalysts can generate CH4 and C2H4, and the sum of their Faraday efficiencies is high, achieving the switching of "CO→C2+" products.

[0020] High activity and stability: Ag-supported reduced silicon carbide 30 Cu 14 The peak partial current density of C2H4 in the nanocluster catalyst reaches 8.5 mA cm⁻¹. -2 The silicon carbide support inhibits the sintering of the active components, and the current density retention rate still reaches 90% after 10 cycles of use. The catalyst maintains a stable current in constant voltage testing.

[0021] Low cost and atomic precision: Atomically precise bimetallic clusters are constructed using Ag and Cu (which are more abundant and cheaper than Au), providing a clear model for the study of CO2RR catalytic mechanism.

[0022] Unique role of the carrier: Silicon carbide can actively induce Ag 30 Cu 14 Cluster reconstruction generates "Ag nanoparticles + CuO" x"Dual active sites (unlike other supports such as CNTs), XPS characterization shows that the Si-O groups on the SiC surface can form hydrogen bonds with the S atoms of the clusters, enhancing interfacial stability; while the inertness of the CNT surface leads to easy cluster aggregation. CuO" x It is the key to the formation of C2+ products, Ag assists CO adsorption, and the two work together to improve the CC coupling efficiency. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 For cluster Ag 30 Cu 14 (TPP)4(SR) 28 Framework structure diagram and single crystal structure diagram (a) with UV-Vis spectrum and cluster crystal photograph (b); Figure 2 Ag supported on silicon carbide 30 Cu 14 XRD pattern of nanocluster catalyst (a), silicon carbide supported Ag 30 Cu 14 Ag loaded in nanocluster catalyst samples 30 Cu 14 UV-Vis absorption spectrum of dichloromethane dissolved in it (b); Figure 3 Ag supported on silicon carbide 30 Cu 14 Scanning electron microscope (SEM) images and corresponding EDS mapping images of nanocluster catalysts; Figure 4 Ag supported on silicon carbide 30 Cu 14 Transmission electron microscopy (TEM) image and corresponding EDS image of nanocluster catalyst; Figure 5 SiC, Ag 30 Cu 14 / SiC and Ag 30 Cu 14 LSV of / SiC-H (a) Faraday efficiency of the product (b) Sum of current densities of all C products (c) Sum of current densities of CH4 and C2H4 (d). Figure 6 For SiC(a), Ag 30 Cu 14 / SiC(b) and Ag30 Cu 14 / SiC-H (c) Capacitive current density and double-layer capacitance obtained based on sweep rate test (d); Figure 7 For Ag 30 Cu 14 / SiC, Ag 30 Cu 14 / SiC-H, Ag 25 Cu4 / SiC and Ag 25 The Faraday efficiency of the LSV products of Cu4 / SiC-H (a), the sum of the current densities of all C products and the sum of the current densities of C2H4 (b). Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] The silver nitrate (AgNO3, 99.85%) used in the specific embodiments of this application were purchased from Sinopharm Chemical Reagent Co., Ltd., copper chloride (CuCl2·6H2O), 3-methylbenzylthiol (SR, purity ≥98%), triphenylphosphine (TPP, purity ≥98%) were purchased from Merrill (Shanghai) Chemical Technology Co., Ltd., sodium borohydride (NaBH4, purity ≥98%), dichloromethane (CH2Cl2, AR grade), and potassium bicarbonate (KHCO3, AR grade) were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0027] Example 1 Silicon carbide-supported Ag 30 Cu 14 The preparation method of nanocluster catalysts includes the following steps: S1. Dissolve 0.18 mmol silver nitrate (AgNO3, purity 99.85%) and 0.23 mmol triphenylphosphine (TPP, purity ≥98%) in 6 mL anhydrous ethanol, stir (80 rpm) for 5 minutes, then add 0.42 mmol 3-methylbenzylthiol (SR, purity ≥98%) and 0.25 mmol copper chloride (CuCl2). (6H2O), react for 10 minutes, then centrifuge at 8000 rpm for 3 minutes, remove the supernatant and collect the precipitate; S2. Disperse the precipitate in 16 mL of anhydrous ethanol-dichloromethane mixed solution (anhydrous ethanol to dichloromethane volume ratio 1:1), then add 2 mL of 0.40 M NaBH4 ethanol solution, stir (100 rpm) for 6 hours, then centrifuge at 10000 rpm for 3 minutes to collect Ag. 30 Cu 14 (TPP)4(SR) 28 The precipitate was dissolved in dichloromethane at a mass-to-volume ratio of 1:25. Then, n-hexane was diffused into the dichloromethane solution at a rate of 0.5 mL / h for one week at 25 °C to obtain Ag clusters. 30 Cu 14 ; S3, 10mg of Ag cluster 30 Cu 14 Dissolved in 20 mL of dichloromethane, 100 mg of silicon carbide (commercially purchased β-SiC powder, average particle size 50 nm, specific surface area 35 m² / g, acid-washed with 1 mol / L HCl for 2 hours and then vacuum-dried before use) was added. The mass ratio of clusters to silicon carbide was 1:10 (loading was 9.1 wt%, determined by ICP-MS). After ultrasonic treatment (ultrasonic frequency 35 kHz, ultrasonic power 250 W) for 10 minutes, the solution was sealed in a rotary evaporator at 30 °C and rotary evaporated for 50 minutes (vacuum 0.1 MPa, rotation speed 150 rpm). The solid was collected to obtain silicon carbide-loaded Ag. 30 Cu 14 Nanocluster catalysts (Ag) 30 Cu 14 / SiC).

[0028] Example 2 Silicon carbide-supported Ag 30 Cu 14 The method for reducing nanocluster catalysts includes the following steps: taking 20 mg of silicon carbide-supported Ag 30 Cu 14 Nanoclusters were added to 20 mL of 0.4 mol / L NaBH4 solution and sonicated (ultrasonic frequency 35 kHz, ultrasonic power 200 W) for 1 hour. Then, the mixture was centrifuged at 8000 rpm for 3 minutes, the supernatant was removed, and the precipitate was collected. The precipitate was washed three times with deionized water and once with anhydrous ethanol, and dried at 60 °C for 12 hours. This process was repeated four times to obtain reduced silicon carbide-loaded Ag. 30 Cu 14 Nanocluster catalysts (Ag) 30 Cu 14 / SiC-H). XPS characterization showed that the reduced Cu 2p peak was located at 933.6 eV, corresponding to CuO. xHRTEM revealed that the Ag particles had a diameter of approximately 3.2 nm. After 10 cycles, the Ag / Cu ion concentration in the electrolyte was found to be below 0.1 ppm by ICP-MS, and the current density retention rate reached 90%.

[0029] Example 3 Silicon carbide-supported Ag 30 Cu 14 The application of nanocluster catalysts in electrocatalytic CO2 reduction includes the following steps: Weigh 5.0 mg of silicon carbide-supported Ag. 30 Cu 14 Nanocluster catalysts or Ag supported on reduced silicon carbide 30 Cu 14 The nanocluster catalyst was placed in a test tube, and 500 μL of anhydrous ethanol and 20 μL of Nafion solution were added to the test tube respectively. The mixture was ultrasonically dispersed for 1 h to form a homogeneous slurry. Then, 300 μL of the slurry was pipetted onto the surface of a 1.0 cm × 3.0 cm diameter carbon paper and allowed to air dry. This slurry served as the working electrode. 1 M KHCO3 was used as the electrolyte, with the catalyst-loaded side of the carbon paper in contact with the electrolyte and the unloaded side connected to the gas chamber. The CO2 flow rate was 20 mL / min. Ag / AgCl was used as the reference electrode, and a platinum sheet was used as the counter electrode. All potentials were calibrated to the reversible hydrogen electrode based on the reference electrode. The calibration formula was: E(RHE) = E(Ag / AgCl) + 0.0592 × pH + 0.197. Before electrochemical testing, CO2 was first introduced into the electrolytic cell through the working electrode until the flow rate stabilized. The test conditions were -0.8 V to -1.7 V using an electrochemical workstation. Cyclic voltammetry (CV) was performed for 10 cycles at a scan rate of 20 mV / s under conditions of V vs. RHE. Linear sweep voltammetry (LSV) was also performed at a scan rate of 20 mV / s within a test window of -0.8 V to -1.7 V (V vs. RHE). The long-range stability of the samples was tested using chronoamperometric curves (It). All data were corrected using iR.

[0030] Compare with Example 1 In this comparative example, carbon nanorods (CNTs) were used as the support. The CNTs were commercially available, with an average diameter of 10 nm, a length of 5 μm, and a specific surface area of ​​200 m² / g. No surface modification was performed. Ag was prepared using the same method as in Example 1. 30 Cu 14 / CNT catalyst (cluster to CNT mass ratio 1:10).

[0031] Performance testing The Ag cluster prepared in Example 1 30 Cu 14 To characterize, such as Figure 1 As shown, single-crystal X-ray diffraction reveals Ag30 Cu 14 Its crystal structure consists of 30 Ag and 14 Cu metal atoms, 4 TPP and 28 SR ligands, such as Figure 1 As shown in (a), the overall structure can be divided into irregular Ag... 27 nucleus and Ag3Cu 14 (TPP)4(SR) 28 Shell, Ag 27 The nucleus fills the cavity of the shell, Ag 27 The nucleus exhibits irregular stacking. Analyzing one half of the shell, firstly, two P atoms are each bonded to a Cu atom, while the Cu atoms are bonded to shared S atoms, forming CuS2P and CuS3P motifs. Next, all Cu atoms, except for the two Cu atoms bonded by P atoms, are distributed throughout the shell and bonded to three S atoms, forming the CuS3 motif. Subsequently, shared S atoms form strip-shaped half-shells. To further understand Ag... 30 Cu 14 Based on its characteristics, its optical absorption spectrum was obtained using a UV-Vis spectrophotometer, such as... Figure 1 (b) shows that at 370, 555, and 710 nm, Ag 30 Cu 14 It exhibits three distinct absorption peaks, as well as a shoulder peak at 435 nm, confirming the Ag cluster. 30 Cu 14 Successfully prepared. HRTEM observation revealed that Ag... 30 Cu 14 The cluster size in the SiC catalyst is approximately 2.8 nm, while that in the Ag catalyst is... 30 Cu 14 The clusters in / CNT exhibited significant aggregation (particle size 5-10 nm), demonstrating that the SiC support can effectively inhibit cluster aggregation.

[0032] The silicon carbide-supported Ag prepared in Example 1 30 Cu 14 The nanocluster catalyst was characterized, and the catalyst Ag was... 30 Cu 14 / SiC was characterized by XRD, such as Figure 2 As shown, Ag 30 Cu 14 Loading Ag into SiC did not result in any obvious impurity peaks, and the XRD peak positions remained consistent before and after loading, indicating that loading did not cause any change in the SiC crystal structure. 30 Cu 14SiC samples were dispersed in a dichloromethane solution to extract cluster molecules. The supernatant obtained after centrifugation was the solution containing cluster molecules loaded onto SiC. This solution was analyzed by UV-Vis spectroscopy, and the UV spectrum was compared with that of a cluster solution with the theoretical loading concentration. The results are as follows: Figure 2 As shown in (b), the UV-Vis absorption spectrum of the obtained solution and the pure Ag clusters are... 30 Cu 14 The fact that they are almost identical indicates that the cluster structure did not change after loading, suggesting that Ag... 30 Cu 14 The structure remained intact after being loaded onto the SiC surface. Ag was determined by ICP-MS. 30 Cu 14 The SiC catalyst loading was 9.1 wt%. Ag clusters 30 Cu 14 The scanning electron microscope (SEM) results of the SiC-loaded sample are as follows: Figure 3 As shown in the figure, the morphology of SiC did not change significantly. The EDS scan results of the sample show that Ag and Cu elements are uniformly distributed on the surface of the SiC support, indicating that Ag clusters... 30 Cu 14 Uniform loading was applied to the SiC surface. Analysis was performed using transmission electron microscopy, such as... Figure 4 As shown in (a), the cluster Ag 30 Cu 14 The particles are uniformly distributed on the SiC surface, with the particle size mainly concentrated in the range of 2-4 nm. This is consistent with the distribution of Ag clusters. 30 Cu 14 The sizes of the clusters are basically consistent. Furthermore, TEM mapping revealed that Ag and Cu elements are also uniformly distributed on the SiC surface. These results indicate that the clusters were successfully loaded onto SiC and are uniformly distributed on the surface without structural changes.

[0033] Silicon carbide supported on Ag before and after reduction prepared in Examples 1 and 2 30 Cu 14The evaluation of the performance of nanocluster catalysts in electrocatalytic CO2 reduction was conducted. The CO2 gaseous products were quantitatively analyzed using a gas chromatograph (GC9790Ⅱ). The instrument was calibrated with standard gases before testing. The outlet of the cathode chamber of the electrolytic cell was connected to the inlet of the gas chromatograph for real-time gaseous product analysis, with sample analysis performed every 15 minutes. A flame ionization detector (FID) was used to detect CO and other hydrocarbons, and a thermal conductivity detector (TCD) was used to detect H2. Faraday efficiency, the percentage of electricity consumed to produce products within a certain time interval during the reaction, is the most important indicator of catalyst performance. The catalytic performance of the samples in the range of 1.0 to -2.0 V (vs. RHE) was studied using linear sweep voltammetry (LSV). The results are as follows: Figure 5 As shown in (a), the order of current density from largest to smallest is Ag. 30 Cu 14 / SiC-H>Ag 30 Cu 14 / SiC>SiC indicates that the sample Ag 30 Cu 14 / SiC-H exhibits the best activity, and it can also be observed that the Ag sample... 30 Cu 14 The CO2 reduction reaction in SiC-H has the lowest onset potential, indicating that CO2 reacts more readily with Ag in the sample. 30 Cu 14 The active sites of / SiC-H bind and are activated. For example... Figure 5 (b) is the sample SiC, Ag 30 Cu 14 / SiC and Ag 30 Cu 14 The Faraday efficiency plot of the electrocatalytic CO2 reduction products of SiC-H under different bias voltages shows that for pure SiC, the main product is H2, with only a very small amount of CO generated. This indicates that SiC mainly participates in the hydrogen evolution reaction. For Ag... 30 Cu 14 At -0.8 V vs. RHE, the Faraday efficiency of H2 is 45.9%, and that of CO is 54.1%. The yields of H2 and CO are almost equal. As the voltage increases, the Faraday efficiency of H2 decreases, while that of CO gradually increases, reaching a maximum of 98.5% at -1.7 V vs. RHE, indicating that Ag... 30 Cu 14 The selectivity of SiC for CO increases with increasing voltage because Ag 30 Cu 14 The main active sites of the SiC sample are Ag clusters loaded on the surface. 30Cu 14 The introduction of clusters inhibited the hydrogen evolution reaction of SiC; for the reduced Ag sample 30 Cu 14 The same tests were performed on / SiC-H. At low voltage, only H2 and CO were produced. As the applied voltage increased, the Faraday efficiency of H2 decreased. At four different bias voltages (-0.8, -1.1, -1.4, -1.7 V vs. RHE), the Faraday efficiencies of CO were 31.5%, 44%, 52.6%, and 47.1%, respectively, indicating that the Faraday efficiency of CO first increased and then decreased. These results show that at a bias voltage of -1.4 (V vs. RHE), new carbon-containing products (CH4 and C2H4, respectively) appeared. Further increasing the bias voltage, at -1.7 (V vs. RHE), the Faraday efficiency of CH4 was 9.8%, and that of C2H4 was 8.9%, with the peak partial current density of C2H4 reaching 8.5 mA cm⁻¹. -2 This demonstrates the presence of significant multi-carbon products, which differ from the Ag sample before reduction treatment. 30 Cu 14 / SiC comparison, Ag sample after reduction treatment 30 Cu 14 The SiC-H surface underwent reconstruction, and the structure of the active sites changed. XPS characterization showed that the Cu 2p peak after reduction was located at 933.6 eV, corresponding to CuO. x Active sites with high Cu content were exposed. After 10 cycles, the Ag / Cu ion concentration in the electrolyte was below 0.1 ppm as detected by ICP-MS, and the current density retention rate reached 90%. The change in Faraday efficiency demonstrates that the reduced surface reconstruction improved the catalyst's activity in producing multi-carbon products.

[0034] Silicon carbide-supported Ag 30 Cu 14 Verification of the product selectivity performance of nanocluster catalysts, such as Figure 5 As shown in (c), the partial current density for the catalyst to produce C products was calculated. Compared with the other two catalysts, sample Ag... 30 Cu 14 The / SiC catalyst exhibits the highest current density due to its high CO selectivity. Further evaluation of catalyst selectivity involved calculating the sum of the partial current densities for CH4 and C2H4, such as... Figure 5 As shown in (d), with the increase of voltage, the sample Ag... 30 Cu 14 The current density corresponding to / SiC-H shows an increasing trend, indicating that this sample produces the highest yield of CH4 and C2H4, suggesting that the sample Ag... 30 Cu 14 / SiC-H has a more suitable environment for generating multi-carbon products.

[0035] The electrochemical active area of ​​the catalyst was tested in the non-Radida region, and the test results are as follows: Figure 6 As shown, SiC exhibits the highest electrochemical active area, which is due to SiC's inherent good hydrogen production performance, as can be seen from its Faraday efficiency. Figure 6 As shown in (b), the contribution of SiC to the active area is mainly due to its greater number of hydrogen-producing active sites and the loading of Ag clusters. 30 Cu 14 Sample Ag 30 Cu 14 In SiC, because the cluster ligands are organic compounds, the organic matter on the SiC surface covers the original hydrogen-producing active sites, increasing the Ag content. 30 Cu 14 The active sites for CO production. The Ag sample treated with NaBH4 reduction... 30 Cu 14 The active area of ​​the / SiC-H group continued to decrease, indicating that the clusters underwent surface reconstruction rather than loss (the Ag / Cu ion concentration in the electrolyte was below 0.1 ppm as detected by ICP-MS). The organic ligands of the clusters were partially removed, forming new "Ag nanoparticles + CuO" structures. x "Dual active sites (XPS showed the Cu 2p peak at 933.6 eV, corresponding to CuO)" x These new active sites are conducive to the production of CH4 and C2H4.

[0036] Compared with Example 1, carbon nanorods (CNTs) with better conductivity were selected as the support to prepare sample Ag. 30 Cu 14 / CNT, refer to Ag processing 30 Cu 14 The experimental conditions for / SiC involved reduction treatment with NaBH4, and the treated sample was labeled as Ag. 30 Cu 14 / CNT-H. Sample Ag 30 Cu 14 / CNT and Ag 30 Cu 14 / CNT-H was electrochemically tested in a flow electrolytic cell, and the test results were combined with Ag. 30 Cu 14 / SiC and Ag 30 Cu 14 Analyzing the data of / SiC-H, the Faraday efficiency plot of the product (e.g.) Figure 7 a) The Faraday efficiency of C2H4 relative to that of sample Ag at -1.7 V vs. RHE.30 Cu 14 / CNT actually decreased by only 1.2%, and the current density was only 0.5 mA cm⁻¹. -2 XPS characterization revealed that the Si-O groups on the SiC surface can form hydrogen bonds with the S atoms of the clusters, enhancing interfacial stability and inducing cluster reconstruction; while the CNT surface lacks active functional groups and cannot effectively interact with the clusters, leading to easy cluster aggregation and difficulty in reconstruction to form "Ag nanoparticles + CuO". x "Dual active sites. This indicates that the reduction treatment of NaBH4 did not generate new active sites favorable for C+ product production. This is completely different from choosing SiC as the support, thus proving that the cluster AAG..." 30 Cu 14 Reconstruction on the SiC surface is a unique characteristic of SiC as a carrier.

[0037] The above description is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of this application.

Claims

1. Silicon carbide-supported Ag 30 Cu 14 Nanocluster catalysts, characterized in that, The silicon carbide-supported Ag 30 Cu 14 Nanocluster catalysts are atomically precise Ag 30 Cu 14 Bimetallic nanoclusters, with the chemical formula Ag 30 Cu 14 (TPP)4(SR) 28 Ag supported by silicon carbide 30 Cu 14 Nanoclusters; The silicon carbide-supported Ag 30 Cu 14 The preparation method of nanocluster catalysts includes the following steps: S1. Dissolve silver nitrate and triphenylphosphine in anhydrous ethanol, stir, add 3-methylbenzylthiol and copper chloride, react for 10-15 minutes, centrifuge for 3-5 minutes, remove the supernatant and collect the precipitate; S2. Disperse the precipitate in anhydrous ethanol-dichloromethane mixed solution, then add NaBH4 ethanol solution, stir for 5-6 hours, then centrifuge and collect Ag. 30 Cu 14 (TPP)4(SR) 28 The precipitate was dissolved in dichloromethane, and then n-hexane was diffused into the dichloromethane solution for one week to obtain Ag clusters. 30 Cu 14 ; S3, Ag cluster 30 Cu 14 Dissolved in dichloromethane, silicon carbide was added, and the mixture was ultrasonically treated. Then, it was sealed and subjected to rotary evaporation for 50-60 minutes. The solid was collected to obtain silicon carbide-supported Ag. 30 Cu 14 Nanocluster catalysts.

2. The silicon carbide-supported Ag according to claim 1 30 Cu 14 Nanocluster catalysts, characterized in that, The molar ratio of silver nitrate, triphenylphosphine, 3-methylbenzylthiol, and copper chloride is 15-20:20-25:40-45:23-27.

3. The silicon carbide-supported Ag according to claim 1 30 Cu 14 Nanocluster catalysts, characterized in that, The stirring described in step S1 is performed at a speed of 80-100 rpm for 10-15 minutes.

4. The silicon carbide-supported Ag according to claim 1 30 Cu 14 Nanocluster catalysts, characterized in that, The centrifugation in step S1 is performed at a speed of 7000-8000 rpm.

5. The silicon carbide-supported Ag according to claim 1 30 Cu 14 Nanocluster catalysts, characterized in that, The concentration of the NaBH4 ethanol solution is 0.2-0.6 mol / L.

6. The silicon carbide-supported Ag according to claim 1 30 Cu 14 Nanocluster catalysts, characterized in that, The centrifugation speed in step S2 is 9000-10000 rpm, and the time is 3-5 minutes.

7. The silicon carbide-supported Ag according to claim 1 30 Cu 14 Nanocluster catalysts, characterized in that, The precipitate is dissolved in dichloromethane at a mass-to-volume ratio of 1:20-30.

8. The silicon carbide-supported Ag according to claim 1 30 Cu 14 Nanocluster catalysts, characterized in that, The ultrasonic treatment is performed at a frequency of 20-50kHz, with an ultrasonic power of 100-400W, for a duration of 10-20 minutes.

9. The silicon carbide-supported Ag according to claim 1 30 Cu 14 Nanocluster catalysts, characterized in that, The rotary evaporation is carried out at a temperature of 25-35℃, a vacuum degree of 0.08-0.1MPa, and a rotation speed of 100-150rpm.

10. A silicon carbide-supported Ag according to any one of claims 1-9 30 Cu 14 Application of nanocluster catalysts in electrocatalytic CO2 reduction.

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