A method for preparing a copper-alkaline earth metal bimetallic composite catalyst and its application in the electrocatalytic production of multi-carbon products from CO2.

Abstract

This invention discloses a method for preparing a copper-alkaline earth metal bimetallic composite catalyst and its application in the electrocatalytic generation of multi-carbon products from CO2. Based on an in-situ atmospheric CO2 capture and spatial confinement strategy, this invention mixes copper and strontium salts in an alkaline liquid phase. Utilizing the carbonation kinetics of slow CO2 absorption at the gas-liquid interface, a rod-shaped SrCO3 framework is formed through self-assembly. Subsequently, through confined penetration and selective in-situ reduction by a reducing agent, a high-density Cu-O-Sr bridging oxygen bond is constructed. The structure is then freeze-dried to solidify the catalyst. In this catalytic material, the SrCO3 framework optimizes mass transfer and inhibits copper particle sintering, while the Cu-O-Sr interface stabilizes the metastable Cu through strong electronic interactions. + This significantly reduces the formation energy barrier of the key C-C coupling intermediate (*OCCHO), thereby greatly improving the Faraday efficiency and long-term stability of electrocatalytic CO2 to ethylene conversion.

Description

Technical Field

[0001] This invention relates to the field of catalytic materials, and in particular to a method for preparing a copper-alkaline earth metal bimetallic composite catalyst and its application in the electrocatalytic generation of multi-carbon products from CO2. Background Technology

[0002] Electrocatalytic conversion of carbon dioxide (CO2) into high-value-added chemicals (especially ethylene, a core raw material in the chemical industry) is an important pathway for waste resource utilization. Electrically driven CO2 reduction reactions (CO2RR) can produce single-carbon products (C1, such as CO and methanol) and multi-carbon products (C2, C4, C5, C6, C7, C8, C9 ... 2+ (such as ethylene, ethanol), where C 2+ The products have become a research focus due to their higher economic value, but the directed conversion of CO2 to ethylene still faces multiple challenges: on the one hand, the competitive hydrogen evolution reaction (HER) in the CO2RR process significantly reduces catalytic efficiency, and efficient C-C bond coupling is difficult to achieve; on the other hand, although copper-based catalysts (especially those containing Cu(I) species) have excellent C-C bond properties, the catalytic efficiency of the products is still limited. 2+ Selectivity has become the mainstream system, but it is prone to self-reduction and undesirable reconstruction during the reaction, which leads to the loss of Cu(I) active species, thereby limiting the selectivity and catalytic stability of ethylene.

[0003] Studies have shown that in the CO2RR process, controlling the oxidation state to achieve Cu 0 and Cu + A proper balance is crucial for the conversion of CO2 to C2H4. Cu + The site enhances the adsorption of CO (*CO), promoting CC coupling and thus efficiently generating C2H4. Although several strategies for modulating the local catalyst microenvironment have been proposed, including optimization of local coordination structures, electrode-electrolyte interface, and equilibrium adsorption of carbon intermediates, precise control remains difficult. Deep hydrogenation derived from C1 intermediates (C1 pathway) and CC coupling kinetics (C2H4) are key factors. 2+ Competition exists between pathways. Therefore, it is essential to improve the electrochemical selectivity of Cu-based catalysts while maintaining their catalytic activity. Summary of the Invention

[0004] This invention targets metastable Cu during the electrocatalytic CO2 reduction process. + It is easily reduced to metallic Cu. 0 This leads to problems such as loss of active sites on the catalyst surface and difficulty in controlling the adsorption behavior of key intermediates. To address these issues, a method for preparing copper-alkaline earth metal bimetallic composite catalysts driven by in-situ carbonation and interface confinement construction is provided, along with its application in the generation of multi-carbon products.

[0005] In this invention, atmospheric CO2 is first captured using an open, strongly alkaline system, driving the in-situ generation of the SrCO3 framework through slow gas-liquid phase mass transfer kinetics. Subsequently, a high-density Cu-O-Sr heterostructure is constructed on the SrCO3 framework through in-situ dehydration condensation and selective reduction at the interface. This design enables the control of the microstructure, heterostructure interface bonding, and electronic states of the surface active centers of the bimetallic catalyst. The catalyst, through a unique hierarchical structure and interfacial coordination synergistic engineering, precisely constructs a strongly bonded Cu-O-Sr coordination structure on the SrCO3 support. This structure not only stabilizes the highly active metastable copper valence state but also exhibits a dual effect of orbital hybridization and geometric confinement under electroreduction conditions, providing an excellent adsorption configuration and coupling microenvironment for key carbon-based intermediates, thereby efficiently driving the generation of multi-carbon products (ethylene).

[0006] This invention precisely designs the crystallization behavior and coordination structure of catalytic materials by controlling the in-situ carbonated SrCO3 framework construction and the in-situ interfacial anchoring strategy under controlled synthesis atmosphere. 1. Confined crystallization under CO2 atmosphere control and in-situ carbonation of SrCO3 framework construction This invention places the reaction system in an open environment, slowly adding liquid alkali to adjust the pH of the system between 10 and 12. This alkaline microenvironment combined with the open system has a dual effect: it constructs a highly efficient atmospheric CO2 capture window, promoting the continuous and extremely slow conversion of free CO2 into CO3 at the gas-liquid interface. 2- By strictly confining the system to a range of extremely low carbonate supersaturation, SrCO3 undergoes confined nucleation and anisotropic growth; this promotes the growth of Cu in the system. 2+ A moderate conversion to highly reactive polynuclear hydroxyl complexes makes them easily captured by the high-density surface defects derived from the slow crystallization of SrCO3. If the pH is too low (<10), the liquid-phase absorption of CO2 and carbonatization kinetics are hindered, preventing effective in-situ formation of the SrCO3 framework; if the pH is too high (>12), it will lead to Sr... 2+ With CO3 2- Rapid nucleation and dense growth not only result in the loss of high specific surface area, but also lead to the absence of surface defect sites, thereby fundamentally blocking the in-situ construction of subsequent Cu-O-Sr interface coordination bonds.

[0007] 2. In-situ construction and solidification of active electronic states of Cu-O-Sr coordination bonds After the SrCO3 framework is formed, Cu in the liquid phase 2+Hydroxyl complexes specifically target and anchor at high-density defects on the framework surface, inducing and undergoing in-situ dehydration condensation reactions, leading to high-density Cu-O-Sr bridging oxygen coordination bonds at the nanoscale. During selective reduction with hydrazine hydrate, the reduction kinetics of copper species are significantly depressed due to the spatial confinement effect of the SrCO3 framework and the strong interfacial electronic traction generated by the Cu-O-Sr coordination bonds. The reducing agent can only reduce the Cu species exposed at the interface. 2+ Some copper is reduced to a lower valence state, while the copper adjacent to the interface is held in place by molecular-level contact and is firmly locked in the metastable Cu state. + Highly active Cu was successfully constructed. + / Cu 0 Coexisting phase. Under actual electrocatalytic conditions, this dynamically stable Cu-O-Sr coordination interface optimizes the d-band center of Cu sites, significantly enhancing the surface adsorption coverage of the key intermediate CO; at the same time, in conjunction with the characteristic geometric configuration of the support, it greatly reduces the formation energy barrier of the CC-coupled key intermediate (*OCCHO), essentially suppressing the hydrogen evolution side reaction and actively guiding the reaction pathway to the directional conversion of multi-carbon products such as ethylene.

[0008] This invention achieves the control of microstructure, heterogeneous interface bonding, and electronic states of surface active centers by regulating the in-situ carbonated SrCO3 framework construction and interface in-situ anchoring strategy, thereby significantly improving the Faraday efficiency of electrocatalytic ethylene production.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a copper-alkaline earth metal bimetallic composite catalytic material includes the following steps: S1: Add divalent copper salt and strontium salt to deionized water, heat and stir to dissolve, and obtain a clear mixed metal cation solution; S2: The solution described in step S1 is placed in an open atmospheric atmosphere. Under heating and stirring, an alkaline solution is added dropwise to adjust the pH of the system to 10-12. Then, the reaction is continued at a constant temperature with stirring, so that the reaction solution spontaneously absorbs CO2 from the air and reacts with strontium ions to generate the SrCO3 framework. S3: Add a reducing agent solution dropwise to the reaction solution obtained in step S2, and carry out the reduction reaction under heating and stirring. The selective interfacial reduction of copper species is completed in a confined space. After cooling, solid-liquid separation, washing and drying, copper-alkaline earth metal bimetallic composite catalyst material is obtained.

[0010] Further, in step S1, the molar ratio of divalent copper salt to strontium salt is 1:(0.5-2), preferably 1.5-2:1. At this ratio, the exposed area of ​​the Cu-O-Sr interfacial bonding is maximized. + Species stability is optimal.

[0011] Furthermore, in step S1, both the divalent copper salt and the strontium salt are nitrates.

[0012] The entire reaction process in this invention is carried out under open atmospheric conditions. In a high-purity carbon dioxide atmosphere, the reaction leads to excessive carbonization, resulting in excessive proliferation of SrCO3 crystals, physically shielding the active interface and causing a similar performance degradation. In a high-purity nitrogen atmosphere, SrCO3 nuclei fail to form, leading to severe nanoscale sintering and deep oxidation of copper species, thus significantly deteriorating the ethylene production kinetics.

[0013] Furthermore, in step S1, the total concentration of divalent copper salt and strontium salt in deionized water is 0.05-0.15 M. This specific pH range and controlled dropping kinetics can generate key microenvironment and assembly regulation effects: On the one hand, this alkaline range constructs an efficient "gas-liquid" CO2 capture window, promoting the continuous dissolution and conversion of free CO2 in the air into CO3 at the gas-liquid interface. 2- This drives the slow nucleation and anisotropic growth of the SrCO3 hierarchical porous framework; on the other hand, it allows Cu in the system to... 2+ The Cu hydroxyl species are moderately converted into highly active polynuclear hydroxyl complexes. The high-density surface defects generated during the slow crystallization of the SrCO3 framework induce in-situ dehydration condensation between Cu hydroxyl species and unsaturated oxygen species on their surface, thereby initially anchoring and constructing strongly interacting Cu-O-Sr interfacial bridging oxygen bonds at the nanoscale.

[0014] Furthermore, in step S2, the heating temperature is 40-65℃, preferably 55-60℃, and after adjusting the pH to 10-12, the reaction is continued at a constant temperature with stirring for 0.5-1h.

[0015] Further, in step S3, the reducing agent solution is a hydrazine hydrate solution, and the molar ratio of the hydrazine hydrate solution to the total molar ratio of the divalent copper salt and strontium salt in step S1 is 5-12:1, preferably 8-10:1.

[0016] Furthermore, in step S3, the reduction reaction temperature is 50-60℃, and the reaction time is 1-4h.

[0017] The specific mild reduction conditions of this invention, highly synergistic with the spatial confinement effect of the SrCO3 framework, achieve precise localized reduction and metastable solidification of active copper species. Thanks to the strong interfacial electron traction effect generated by the Cu-O-Sr bridging bonds constructed in the lead, the reduction kinetics of copper species anchored at the interface are significantly delayed; the reducing agent can only reduce the outer Cu layers, which are not strongly constrained by the interface. 2+ Reduced to metallic Cu 0 Meanwhile, the copper species adhering closely to the interface were successfully stabilized in the metastable state of Cu. + This allows for the construction of highly active CuO at the nanoscale.x -SrCO3 multiple cooperating sites.

[0018] Controlling the reduction time and kinetic window is crucial: if the isothermal reduction time is insufficient, the reducing agent will not be fully reduced, and there will be a lack of sufficient Cu at the interface. + / Cu 0 The coexisting phase cannot synergistically optimize the adsorption of CO intermediates; if the time is too long, it may cause excessive reduction of Cu species and particle ripening.

[0019] This invention also discloses a copper-alkaline earth metal bimetallic composite catalytic material for the electrocatalytic generation of multi-carbon products C from CO2. 2+ Applications in [the context of the text].

[0020] It should be clarified that the product directly obtained by the above preparation method is a copper-alkaline earth metal bimetallic composite catalyst with Cu-O-Sr interfacial bonding. The Cu-O-Sr interfacial bonding constructed during the catalytic process plays a crucial structure-directing role: Sr species transfer electrons to Cu sites through Cu-O-Sr bridging oxygen bonds at the interface, stabilizing the intrinsically metastable Cu on the surface of the catalyst Cu particles. + Species that prevent complete reduction to Cu under strong reduction potentials. 0 This allows for the formation of stable Cu on the catalyst surface. + / Cu 0 Mixed valence states. This valence state balance is a prerequisite for efficient CC coupling. At the same time, the SrCO3 framework induces Cu grains to grow along the (111) crystal plane orientation, exposing more active crystal planes that are conducive to the asymmetric coupling of *CO and *CHO.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are: 1) The introduction of an alkaline earth metal framework constructs a synergistic system on copper-based catalysts, combining physical anchoring and dispersion with interfacial Cu-O-Sr bonding regulation. This unique "framework anchoring-interfacial bonding synergy" engineering can fundamentally regulate the geometric distribution and electronic state of active copper sites, stabilizing the Cu required for catalysis. + / Cu 0 Mixed valence states were investigated, and the adsorption behavior for key CC coupling intermediates was optimized. During electrocatalysis, the Cu-O-Sr interfacial bridging oxygen bond transferred partial charge to the Cu site through electronic interactions, effectively suppressing metastable Cu. +The species exhibits excessive reduction and deactivation under strong reduction potentials. More importantly, this interfacial structure significantly lowers the key energy barrier for the asymmetric coupling of *CO and *CHO intermediates to form *OCCHO, providing a reaction pathway with a lower energy barrier for the formation of CC bonds, thereby actively guiding the reaction towards multi-carbon products such as ethylene. Simultaneously, the physical anchoring effect of the alkaline earth metal SrCO3 framework effectively inhibits the migration and sintering of Cu particles under electrochemical conditions, significantly improving the catalyst's structural durability and active site retention during long-term operation.

[0022] 2) The copper-alkaline earth metal bimetallic composite catalytic material of the present invention can efficiently and selectively convert CO2 into high-value C. 2+ The product (especially ethylene) is effectively suppressed, and competing hydrogen evolution reactions and single-carbon product formation pathways are inhibited, achieving simultaneous improvement in catalytic activity, selectivity, and stability. Experimental results show that the catalytic material of this invention exhibits good performance at 200 mA·cm⁻¹. -2 It can operate stably for 60 hours under constant current conditions, and its electrocatalytic CO2 reduction of C 2+ The product's Faraday efficiency exceeded 88%, with the ethylene Faraday efficiency reaching 81%. Compared with the pure copper catalyst without alkaline earth metal modification, the copper-alkaline earth metal bimetallic composite catalyst improved the Faraday efficiency of electrocatalytic CO2 reduction to ethylene by about 30%. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope (SEM) image of the electrocatalytic material sample from Example 1.

[0024] Figure 2 This is the XRD pattern of the electrocatalytic material sample from Example 1.

[0025] Figure 3 This is an XPS Cu LMM image of the electrocatalytic material sample from Example 1.

[0026] Figure 4 The electrocatalytic material sample of Example 1 was subjected to a constant current density of -200 mA / cm². 2 Stability test results under (vs Ag / AgCl) conditions.

[0027] Figure 5 This is a scanning electron microscope (SEM) image of the electrocatalytic material sample from Example 2.

[0028] Figure 6 This is a scanning electron microscope (SEM) image of the electrocatalytic material sample from Example 3.

[0029] Figure 7 This is an SEM image of the electrocatalytic material sample from Comparative Example 1. Detailed Implementation

[0030] The technical solution of the present invention will be further described below through specific embodiments.

[0031] In this invention, unless otherwise specified, all raw materials and equipment used are commercially available or commonly used in the art. The methods described in the examples, unless otherwise specified, are conventional methods in the art. Unless otherwise indicated, all parts are by weight, temperatures are expressed in °C or at ambient temperature, and pressures are at or near atmospheric pressure. Various variations and combinations of reaction conditions (e.g., component concentrations, required solvents, solvent mixtures, temperature, pressure, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the product obtained by the method exist, requiring only reasonable routine experiments to optimize such method conditions.

[0032] Example 1: A method for preparing a copper-alkaline earth metal bimetallic composite catalytic material, comprising the following steps: S1: Dissolve 0.8 mmol of strontium nitrate in 25 mL of deionized water to prepare a 0.032 mol / L strontium salt solution, and transfer it to a beaker. Then, add 1.2 mmol of copper nitrate trihydrate to the above solution and stir until completely dissolved under a 60 °C water bath, obtaining a clear mixed cation solution. The entire reaction was carried out in an open atmospheric atmosphere. Calculations show that the copper ion concentration in the solution is approximately 0.048 mol / L, and the molar ratio of copper to strontium is approximately 1.5:1.

[0033] S2: Under constant temperature of 60 ℃ and continuous stirring, add 1.0 mol / L NaOH solution to the solution from step S1 using a constant flow pump at a dropping rate of 0.8 mL / min to adjust the pH of the system to 10⁻¹¹. After the addition is complete, continue stirring at the same temperature for 0.5 hours, and the system gradually forms a coprecipitate precursor.

[0034] S3: Measure 2 mL of a 50% hydrazine hydrate (N2H4·H2O) solution and slowly add it dropwise to the mixed solution obtained in the previous step using a constant flow pump at the same dropping rate of 0.8 mL / min while continuously stirring. After the addition is complete, continue stirring at 60 °C for 2 hours to ensure that the reduction reaction proceeds fully and the heterogeneous interface structure is stabilized.

[0035] S4: After the reaction is complete, the reaction system is cooled to room temperature, and the solid product is collected by centrifugation. This solid is washed three times with distilled water and three times with ethanol to remove soluble impurities. Finally, the resulting dark red precipitate is placed in a vacuum freeze dryer and dried at -50 °C for 24 hours to obtain the target product CuO. x -SrCO3 composite catalyst material.

[0036] The catalytic material prepared in Example 1 was analyzed by SEM, such as... Figure 1 As shown, CuO x - Irregularly protruding particles adhere to the surface of the SrCO3 composite catalyst, increasing the surface roughness of the structure. For example... Figure 2 XRD analysis confirmed the successful synthesis of a non-alloyed copper-alkaline earth metal bimetallic composite catalytic material. Figure 3 Cu LMM test proves that Cu is Cu + / Cu 0 It exists in the form of mixed valence states.

[0037] Example 2: The preparation method of the catalyst material in Example 2 is the same as that in Example 1, except that "the entire process is carried out under a high-purity CO2 gas atmosphere (purity ≥ 99.99%), that is, high-purity CO2 is introduced into the solution in steps S1-S3". All other conditions remain unchanged, and the target product CuO is finally obtained. x -SrCO3-CO2 composite catalytic material.

[0038] Example 2 in Example 1 (CuO) x Based on the exact same material ratio and core process as Cu-O-SrCO3, a CO2 atmosphere was introduced as a variable in the synthesis process. This operation aimed to study the influence of the CO2 gas environment on the composition of the co-precipitated precursor, crystal growth kinetics, and the final Cu-O-Sr interface structure. Compared with the sample without CO2, the material (CuO-SrCO3) synthesized under this condition... x The significant differences in phase, surface chemical state, and microstructure of the -SrCO3-CO2 catalysts not only verify the adaptability of the method of the present invention under certain process changes, but also provide a feasible technical path for finely adjusting the interfacial properties of the catalyst by controlling the synthesis atmosphere, further enriching the content of the present invention.

[0039] The SEM image of the electrocatalytic material sample in Example 2 is shown below. Figure 5 As shown, the reaction in a high-purity carbon dioxide atmosphere will lead to excessive carbonization, resulting in excessive proliferation of SrCO3 crystals, which physically shields the active interface and causes a similar performance decline.

[0040] Example 3: The preparation method of the catalyst material in Example 3 is the same as that in Example 1, except that "the entire process is carried out under a high-purity N2 gas atmosphere (purity ≥ 99.99%), that is, high-purity N2 is introduced into the solution in steps S1-S3". All other conditions remain unchanged, and the target material CuO is finally obtained. x -SrCO3-N2.

[0041] The SEM image of the electrocatalytic material sample in Example 3 is shown below. Figure 6As shown, SrCO3 nuclei failed to form in a high-purity nitrogen atmosphere, leading to severe nanoscale sintering and deep oxidation of copper species, which significantly deteriorated the ethylene production kinetics.

[0042] Comparative Example 1: CuO without strontium doping x catalyst This comparative example provides a method for preparing a pure copper oxide reference material without the introduction of strontium, to be compared with the bimetallic composite material containing the Cu-O-Sr interface structure described in this invention, to verify the key role of strontium introduction and interface structure construction. The preparation steps of the catalyst in Comparative Example 1 are as follows: S1: Accurately weigh 240 mg of copper nitrate trihydrate, dissolve it in 10 mL of deionized water to prepare a 0.1 mol / L copper salt solution, transfer it to a beaker, and stir until completely dissolved under a 60 ℃ water bath. The entire reaction is carried out in an open atmospheric atmosphere.

[0043] S2: Under constant temperature of 60 ℃ and continuous stirring, add 1.0 mol / L NaOH solution to the solution from step S1 using a constant flow pump at a dropping rate of 0.8 mL / min to adjust the pH of the system to 10⁻¹¹. After the addition is complete, continue stirring at the same temperature for 0.5 hours to form copper hydroxide or copper oxide hydrate precipitate.

[0044] S3: Measure 2 mL of a 50% hydrazine hydrate solution and, with continuous stirring, slowly add it dropwise to the mixed solution obtained in the previous step using a constant flow pump at a dropping rate of 0.8 mL / min. After the addition is complete, maintain the water bath temperature at 60 °C and continue stirring for 2 hours.

[0045] S4: After the reaction was complete, the resulting suspension was cooled to room temperature, and the solid precipitate was collected by centrifugation. The precipitate was washed three times with distilled water and three times with ethanol. Finally, the obtained solid was placed in a vacuum freeze dryer and dried at -50 °C for 24 hours to obtain the control sample CuO. x Catalytic materials.

[0046] The catalytic material prepared in Comparative Example 1 was analyzed by SEM, such as... Figure 7 As shown, CuO x It exhibits an irregular granular cluster structure.

[0047] Comparative Example 2: CuO doped with metallic calcium x catalyst Comparative Example 2: The preparation method of the catalyst material was the same as in Example 1, except that "strontium nitrate was replaced with an equal molar amount of calcium nitrate". All other conditions remained unchanged, and the target material CuO was finally obtained. x -CaCO3.

[0048] Comparative Example 3: CuO doped with barium metal x catalyst Comparative Example 3: The preparation method of the catalyst material was the same as in Example 1, except that "strontium nitrate was replaced with an equal molar amount of barium nitrate". All other conditions remained unchanged, and the target material CuO was finally obtained. x -BaCO3.

[0049] Comparative Example 4: CuO doped with metallic magnesium x catalyst Comparative Example 4: The preparation method of the catalyst material was the same as in Example 1, except that "strontium nitrate was replaced with an equal molar amount of magnesium nitrate". All other conditions remained unchanged, and the target material CuO was finally obtained. x -MgCO3.

[0050] Application Example 1: The catalyst materials of each example and comparative example were used for electrocatalysis. The specific operation steps are as follows: Weigh 10 mg of catalyst material into a vial, add 960 μL of isopropanol and 40 μL of Nafion solution (Nafion solution mass fraction is 5%), mix, and sonicate for 2 hours to completely disperse the catalyst and obtain a uniform catalyst ink.

[0051] 300 μL of the catalyst ink prepared above was uniformly sprayed onto one side of a 1 cm × 3 cm carbon paper. After drying, it was used as the working electrode, with a platinum sheet as the anode and an Ag / AgCl electrode as the reference electrode. Catalytic performance testing was conducted using a Wuhan KOST CS2350H electrochemical workstation in a flow cell with a three-electrode system. The anode and cathode were separated by an anion exchange membrane, and the electrolyte in both chambers was a 0.5 mol / L KOH aqueous solution. The electrochemical workstation applied -600 mA / cm². 2 The electrocatalytic reaction was polarized by a constant current density (vsAg / AgCl). During the electrocatalysis process, CO2 gas was introduced at a flow rate of 10 ml / min into the cathode chamber of the flow cell. The gas in the cathode flow cell was introduced from bottom to top. After the current stabilized, the product was collected for 15 s and introduced into the gas phase. The Faraday efficiency was calculated based on the peak area concentration of the gas product measured in the gas phase. The results of the electrocatalytic reaction for 10 min are shown in Table 1.

[0052] Table 1 .

[0053] As can be seen from the table above, the electrocatalyst material obtained in the optimal Example 1 of this invention is CuO. x -SrCO3 composite catalyst material, ethylene Faraday efficiency is 81.01%; C 2+The product Faraday efficiency was 88.27%. The electrocatalyst in Comparative Example 1 was CuO in a mixed valence state. x The Faraday efficiency of ethylene is 48.28%; C 2+ The product Faraday efficiency was 58.26%. This demonstrates that the copper-alkaline earth metal bimetallic composite catalytic material of the present invention exhibits significantly improved electrocatalytic performance.

[0054] In addition, the stability testing experiments for electrocatalytic materials are generally conducted at -200 to -300 mA / cm². 2 The electrocatalytic process was carried out under a constant current density (vs Ag / AgCl), and the constant current density was changed to -200 mA / cm² according to the above electrocatalytic process. 2 Under the conditions of (vs Ag / AgCl), the results of the stability test of the electrocatalytic material in Example 1 after 60 h are shown in the figure. Figure 4 This shows that the catalyst has good catalytic stability. Figure 4 The Faraday efficiency results, from bottom to top, correspond to H2, C2H4, and multi-carbon products C, respectively. 2+ .

[0055] Compared to Example 1: ① In Example 2, the synthesis conditions involved continuously introducing high-purity carbon dioxide during synthesis. Excessive carbonization in the high-purity carbon dioxide atmosphere led to excessive proliferation of SrCO3 crystals, physically shielding the active interface and causing a similar performance degradation. ② In Example 3, the synthesis conditions involved continuously introducing high-purity nitrogen gas during synthesis. Figure 5 It can be observed that the particles are tightly aggregated, which reduces the exposed area of ​​metallic strontium on the material surface, thereby reducing specific active sites; this inhibits the catalytic ability of the catalyst and results in unsatisfactory catalyst stability.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a copper-alkaline earth metal bimetallic composite catalytic material, characterized in that, Includes the following steps: S1: Add divalent copper salt and strontium salt to deionized water, heat and stir to dissolve, and obtain a clear mixed metal cation solution; S2: The solution described in step S1 is placed in an open atmospheric atmosphere. Under heating and stirring, an alkaline solution is added dropwise to adjust the pH of the system to 10-12. Then, the reaction is continued at a constant temperature with stirring, so that the reaction solution spontaneously absorbs CO2 from the air and reacts with strontium ions to generate the SrCO3 framework. S3: Add a reducing agent solution dropwise to the reaction solution obtained in step S2, and carry out the reduction reaction under heating and stirring. The selective interfacial reduction of copper species is completed in a confined space. After cooling, solid-liquid separation, washing and drying, copper-alkaline earth metal bimetallic composite catalyst material is obtained.

2. The method for preparing a copper-alkaline earth metal bimetallic composite catalytic material according to claim 1, characterized in that, In step S1, the molar ratio of divalent copper salt to strontium salt is 1:(0.5-2), preferably 1.5-2:

1.

3. The method for preparing a copper-alkaline earth metal bimetallic composite catalytic material according to claim 1, characterized in that, In step S1, the total concentration of divalent copper salt and strontium salt in deionized water is 0.05-0.15M.

4. The method for preparing a copper-alkaline earth metal bimetallic composite catalytic material according to claim 1, characterized in that, In step S2, the heating temperature is 40-65℃, preferably 55-60℃. After adjusting the pH to 10-12, the reaction is continued at a constant temperature with stirring for 0.5-1h.

5. The method for preparing a copper-alkaline earth metal bimetallic composite catalytic material according to claim 1, characterized in that, In step S3, the reducing agent solution is a hydrazine hydrate solution, and the molar ratio of the hydrazine hydrate solution to the total molar ratio of the divalent copper salt and strontium salt in step S1 is 5-12:1, preferably 8-10:

1.

6. The method for preparing a copper-alkaline earth metal bimetallic composite catalytic material according to claim 1, characterized in that, In step S3, the reduction reaction temperature is 50-60℃ and the reaction time is 1-4h.

7. The method for preparing a copper-alkaline earth metal bimetallic composite catalytic material according to claim 1, characterized in that, In step S1, both the divalent copper salt and the strontium salt are nitrates.

8. A copper-alkaline earth metal bimetallic composite catalytic material prepared by the method according to any one of claims 1-6.

9. The application of the copper-alkaline earth metal bimetallic composite catalytic material according to claim 8 in the electrocatalytic generation of multi-carbon products from CO2.

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