High-selectivity copper-palladium bimetal perovskite material for photocatalytic reduction of co2 to produce ch4 and preparation method thereof

Abstract

The application discloses a high-selectivity copper-palladium bimetal perovskite material for photocatalytic reduction of CO2 to produce CH4 and a preparation method of the material. 2、 Palladium chloride PdCl2, dimethyl sulfoxide DMSO, isopropyl alcohol IPA, hydroxyethyl cellulose, ethyl acetate are prepared; compared with single metal, the bimetallic catalytic material has double active sites and more complex local electronic structure, and is considered as a potential candidate system for CO2 reduction. Efficient bimetallic catalyst is not only a simple combination of two metals, but also can introduce new catalytic sites and mechanisms, affect catalytic performance and product selectivity. In addition, the rich hydroxyl groups in hydroxyethyl cellulose can participate in the photocatalytic CO2 catalytic reaction as a proton source. Compared with the H2O proton source, the hydroxyl groups in the hydroxyethyl cellulose are easier to break, which is beneficial to the proton-coupled electron reaction, and further improves the CH4 selectivity.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a highly selective copper-palladium bimetallic perovskite material for the photocatalytic reduction of CO2 to CH4 and its preparation method. Background Technology

[0002] A complete CO2 to CH4 conversion process involves two half-reactions: CO2 reduction (CO2RR) and H2O oxidation (H2OOR). Both CO2RR and H2OOR involve multi-electron / proton transfer and slow kinetics, and these two half-reactions have a crucial impact on the activity and selectivity of CH4. However, the CO2 to CH4 conversion is an octet reduction process, which is kinetically disadvantageous compared to the CO2 to CO reduction, which requires only 2 electrons. Furthermore, photocatalytic CO2 reduction to CH4 typically involves the transfer of multiple proton-coupled electrons and various C1 intermediates at the active site, resulting in lower yields and selectivity of CH4 formation. Traditional semiconductor photocatalysts have weak CO2 affinity, which is detrimental to CO2 adsorption and activation. On the other hand, the CO2RR rate is limited by H2OOR because H2O is a common proton donor in CO2RR, and efficient proton migration in H2OOR facilitates efficient proton-coupled electron transfer in CO2RR.

[0003] The rational design of catalyst active sites can help accelerate CO2RR and H2OOR efficiencies, thereby improving CH4 yield and selectivity. Metal halide perovskites are an emerging photocatalytic material with great potential in the field of photocatalysis due to their excellent visible light absorption, superior photogenerated carrier transport performance, and flexible bandgap tunability. Cu is considered an effective active metal for accelerating multi-electron and proton transfer CO2RR; therefore, constructing lead-free Cs2CuCl4 host catalysts can help improve CO2RR yield. However, the single Cu catalytic site in Cs2CuCl4 results in poor selectivity for the target product CH4, mainly due to the complex electron transfer on the catalyst surface and poor binding ability of the *CHO intermediate, leading to the occurrence of other competing pathways. Doping engineering is considered an effective method for controlling the active sites of photocatalysts. Therefore, selectively doping Cu sites with other transition metal elements to construct bimetallic site catalysts can adjust the local electronic structure of Cu, thereby affecting CO2 adsorption and activation, as well as the adsorption / desorption energy and conversion barrier of intermediates, improving the selectivity of the target product.

[0004] Water is an important dispersant and proton source for photocatalytic CO2RR; however, most metal halide perovskites decompose rapidly in water due to their ionic nature, affecting their catalytic activity. Hydroxyethyl cellulose (HEC) possesses excellent film-forming properties, allowing bimetallic perovskites to be encapsulated in a membrane, facilitating the reuse of the catalytic material and reducing reaction costs. Furthermore, HEC contains abundant hydroxyl groups, which can serve as a solid proton source for CO2 catalysis. Compared to H2O as a proton source, the hydroxyl groups in HEC are more easily broken, promoting proton-electron coupling and further improving CH4 selectivity. Summary of the Invention

[0005] The purpose of this invention is to design a highly selective copper-palladium bimetallic perovskite material for photocatalytic reduction of CO2 to CH4 and its preparation method. The bimetallic catalytic material of this invention has dual active sites and a more complex local structure.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A highly selective copper-palladium bimetallic perovskite material for the photocatalytic reduction of CO2 to CH4, wherein the material is produced by reacting cesium chloride (CsCl) and copper chloride (CuCl). 2、 It was prepared by palladium chloride (PdCl2), dimethyl sulfoxide (DMSO), isopropanol (IPA), hydroxyethyl cellulose, and ethyl acetate.

[0007] A method for preparing the above-mentioned highly selective copper-palladium bimetallic perovskite material for photocatalytic CO2 reduction to CH4, the method being as follows: Step 1: Weigh out CsCl and CuCl2 and dissolve them in DMSO solvent, then stir with a magnetic stirrer for 1-5 hours; Step 2: Add a certain amount of PdCl2 to the perovskite precursor solution and continue stirring for 0.5-2 h. Then, add a certain amount of IPA antisolvent dropwise to the perovskite precursor solution and sonicate for 0.5-3 h. Step 3: After the reaction is complete, collect the precipitate by centrifugation and wash it with IPA 3-5 times. Dry the obtained sample in a vacuum drying oven at 60-100 ℃ for 4-20 h, and then heat it at 120-200 ℃ for 20-80 min to obtain the copper-palladium bimetallic perovskite material. Step 4: Dissolve a certain amount of hydroxyethyl cellulose in ethyl acetate solvent, then add a certain amount of copper-palladium bimetallic perovskite material, and sonicate for 30-120 min. Step 5: Pour the obtained dispersion into a petri dish, place it in a glass container containing color-changing silica gel, and dry at room temperature for 5-24 hours; Step 6: After the cellulose membrane is completely dry, use tweezers to remove the membrane to obtain the copper-palladium bimetallic perovskite material wrapped in hydroxyethyl cellulose membrane.

[0008] Furthermore, in step 1, the mass of CsCl is 30-100 mg, the mass of CuCl2 is 5-50 mg, and the amount of DMSO used is 1-5 mL.

[0009] Furthermore, in step 2, 5-300 mg of PdCl2 and 5-80 mL of IPA are added.

[0010] Furthermore, in step 4, the mass of hydroxyethyl cellulose is 0.2-2.0 g, the volume of ethyl acetate is 5-30 mL, and the mass of copper-palladium bimetallic perovskite material is 0.05-1 g.

[0011] Compared with the prior art, the present invention has the following beneficial effects: Compared to monometallic catalysts, bimetallic catalytic materials possess dual active sites and more complex local structures, making them highly promising candidate systems for CO2 reduction. Efficient bimetallic catalysts are not merely simple combinations of two metals; they can introduce new catalytic sites and mechanisms, influencing catalytic performance and product selectivity. Furthermore, the abundant hydroxyl groups in hydroxyethyl cellulose can serve as a proton source in the photocatalytic CO2 reaction. Compared to H2O proton sources, the hydroxyl groups in hydroxyethyl cellulose are more easily broken, facilitating proton-electron coupling reactions and further improving CH4 selectivity. Attached Figure Description

[0012] Figure 1 This is a graph showing the yield of photocatalytic CO2 reduction products and CH4 selectivity for different metal halide perovskites.

[0013] Figure 2 This is a graph showing the yield of photocatalytic CO2 reduction products and CH4 selectivity of bimetallic halide perovskites doped with different proportions of Pd.

[0014] Figure 3 This is a graph showing the CO2 reduction product yield and CH4 selectivity of Cs2CuCl4-0.1Pd bimetallic halide perovskite under different proton sources. Detailed Implementation

[0015] The invention will be further described below with reference to the accompanying drawings: like Figure 1-3 As shown, a highly selective copper-palladium bimetallic perovskite material for the photocatalytic reduction of CO2 to CH4 is prepared from cesium chloride (CsCl), copper chloride (CuCl2), palladium chloride (PdCl2), dimethyl sulfoxide (DMSO), isopropanol (IPA), hydroxyethyl cellulose, and ethyl acetate.

[0016] Based on the above materials, the preparation method of the highly selective copper-palladium bimetallic perovskite material for photocatalytic CO2 reduction to CH4 is as follows: Weigh 30-100 mg of CsCl and 5-50 mg of CuCl2 and dissolve them in 1-5 mL of DMSO solvent. Stir with a magnetic stirrer for 1-5 h to obtain a perovskite precursor solution. Then, add 5-300 mg of PdCl2 to the perovskite precursor solution and continue stirring for 0.5-2 h. After stirring, add 5-80 mL of IPA antisolvent dropwise to the perovskite precursor solution; sonicate for 0.5-3 h. After the reaction, collect the precipitate by centrifugation and wash with IPA 3-5 times. Dry the obtained sample in a vacuum drying oven at 60-100 ℃ for 4-20 h, then heat at 120-200 ℃ for 20-80 min to obtain the copper-palladium bimetallic perovskite material. Dissolve 0.2-2.0 g of hydroxyethyl cellulose in ethyl acetate, then add 0.05-1 g of copper-palladium bimetallic perovskite material. Sonicate the mixture for 30-120 min, pour the resulting dispersion into a petri dish, place it in a glass dish containing color-changing silica gel, and dry at room temperature for 5-24 h. After the cellulose membrane is completely dry, remove it with tweezers to obtain the copper-palladium bimetallic perovskite material encapsulated in the hydroxyethyl cellulose membrane. Example 1

[0017] 50 mg of CsCl and 20 mg of CuCl2 were dissolved in 1 mL of DMSO solvent and stirred for 2 h with a magnetic stirrer to obtain a perovskite precursor solution. Then, 50 mg of PdCl2 was added to the perovskite precursor solution, and stirring was continued for 1 h. After stirring, 50 mL of IPA antisolvent was added dropwise to the perovskite precursor solution; the mixture was sonicated for 2 h. After the reaction was complete, the precipitate was collected by centrifugation and washed three times with IPA. The resulting sample was dried in a vacuum drying oven at 60 °C for 10 h, and then heated to 150 °C for 60 min to obtain the copper-palladium bimetallic perovskite material. 0.5 g of hydroxyethyl cellulose was dissolved in 20 mL of ethyl acetate solvent, followed by the addition of 50 mg of the copper-palladium bimetallic perovskite material. The mixture was sonicated for 60 min, and the resulting dispersion was poured into a petri dish and placed in a glass container containing color-changing silica gel. The mixture was then dried at room temperature for 12 h. After the cellulose membrane is completely dry, the membrane is removed with tweezers to obtain the copper-palladium bimetallic perovskite material (Ce / Cs2CuCl4-0.05Pd) encapsulated in hydroxyethyl cellulose membrane. Example 2

[0018] 80 mg of CsCl and 50 mg of CuCl2 were dissolved in 3 mL of DMSO solvent and stirred for 2 h with a magnetic stirrer to obtain a perovskite precursor solution. Then, 100 mg of PdCl2 was added to the perovskite precursor solution, and stirring was continued for 1 h. After stirring, 80 mL of IPA antisolvent was added dropwise to the perovskite precursor solution; the mixture was sonicated for 1 h. After the reaction was complete, the precipitate was collected by centrifugation and washed 5 times with IPA. The obtained sample was dried in a vacuum drying oven at 80 °C for 12 h, and then heated to 180 °C for 30 min to obtain the copper-palladium bimetallic perovskite material. 1.0 g of hydroxyethyl cellulose was dissolved in 30 mL of ethyl acetate solvent, followed by the addition of 100 mg of copper-palladium bimetallic perovskite material. The mixture was sonicated for 30 min, and the resulting dispersion was poured into a petri dish and placed in a glass container containing color-changing silica gel. The mixture was dried at room temperature for 12 h. After the cellulose membrane is completely dry, the membrane is removed with tweezers to obtain the copper-palladium bimetallic perovskite material (Ce / Cs2CuCl4-0.1Pd) encapsulated in hydroxyethyl cellulose membrane. Example 3

[0019] 100 mg of CsCl and 30 mg of CuCl2 were dissolved in 2 mL of DMSO solvent and stirred for 2 h with a magnetic stirrer to obtain a perovskite precursor solution. Then, 150 mg of PdCl2 was added to the perovskite precursor solution, and stirring was continued for 2 h. After stirring, 50 mL of IPA antisolvent was added dropwise to the perovskite precursor solution; the mixture was sonicated for 2 h. After the reaction was complete, the precipitate was collected by centrifugation and washed 5 times with IPA. The obtained sample was dried in a vacuum drying oven at 100 °C for 12 h, and then heated to 180 °C for 30 min to obtain the copper-palladium bimetallic perovskite material. 2.0 g of hydroxyethyl cellulose was dissolved in 25 mL of ethyl acetate solvent, followed by the addition of 100 mg of copper-palladium bimetallic perovskite material. The mixture was sonicated for 60 min, and the resulting dispersion was poured into a petri dish and placed in a glass container containing color-changing silica gel. The mixture was dried at room temperature for 12 h. After the cellulose membrane is completely dry, the membrane is removed with tweezers to obtain the copper-palladium bimetallic perovskite material (Ce / Cs2CuCl4-0.15Pd) encapsulated in hydroxyethyl cellulose membrane. Comparative Example 1

[0020] 50 mg of CsCl and 30 mg of PdCl2 were dissolved in 2 mL of DMSO solvent and stirred with a magnetic stirrer for 1 h to obtain a perovskite precursor solution. Then, 30 mL of IPA antisolvent was added dropwise to the perovskite precursor solution; the mixture was sonicated for 1 h. After the reaction was complete, the precipitate was collected by centrifugation and washed 5 times with IPA. The resulting sample was dried in a vacuum drying oven at 80 °C for 12 h, followed by heating at 150 °C for 60 min to obtain Cs₂PbCl₄ perovskite material. 1.0 g of hydroxyethyl cellulose was dissolved in 30 mL of ethyl acetate solvent, followed by the addition of 100 mg of Cs₂PbCl₄ perovskite material. The mixture was sonicated for 30 min, and the resulting dispersion was poured into a petri dish and placed in a glass dish containing color-changing silica gel. The solution was dried at room temperature for 12 h. After the cellulose membrane is completely dry, the membrane is removed with tweezers to obtain the Cs2PbCl4 perovskite material (Ce / Cs2PbCl4) encapsulated in hydroxyethyl cellulose membrane. Comparative Example 2

[0021] 80 mg of CsCl and 40 mg of CuCl2 were dissolved in 1 mL of DMSO solvent and stirred with a magnetic stirrer for 2 h to obtain a perovskite precursor solution. After stirring, 80 mL of IPA antisolvent was added dropwise to the perovskite precursor solution; the mixture was sonicated for 1 h. After the reaction was complete, the precipitate was collected by centrifugation and washed three times with IPA. The obtained sample was dried in a vacuum drying oven at 80 °C for 12 h, and then heated to 150 °C for 30 min to obtain Cs2CuCl4 perovskite material. 1.5 g of hydroxyethyl cellulose was dissolved in 30 mL of ethyl acetate solvent, and then 80 mg of Cs2CuCl4 perovskite material was added. The mixture was sonicated for 60 min, and the resulting dispersion was poured into a petri dish and placed in a glass container containing color-changing silica gel. The mixture was dried at room temperature for 10 h. After the cellulose membrane is completely dry, the membrane is removed with tweezers to obtain the Cs2CuCl4 perovskite material (Ce / Cs2CuCl4) wrapped with hydroxyethyl cellulose membrane. Comparative Example 3

[0022] 50 mg of CsCl and 15 mg of CuCl2 were dissolved in 1 mL of DMSO solvent and stirred for 2 h with a magnetic stirrer to obtain a perovskite precursor solution. Then, 100 mg of PdCl2 was added to the perovskite precursor solution, and stirring was continued for 2 h. After stirring was complete, 80 mL of IPA antisolvent was added dropwise to the perovskite precursor solution; the mixture was then sonicated for 2 h. After the reaction was complete, the precipitate was collected by centrifugation and washed 5 times with IPA. The resulting sample was dried in a vacuum drying oven at 80 °C for 10 h, and then heated to 150 °C for 30 min to obtain copper-palladium bimetallic perovskite powder material (Cs2CuCl4-0.1Pd).

[0023] In Examples 1-3, the high selectivity of photocatalytic CO2 reduction to CH4 obtained by the technical solution of the present invention is due to the synergistic effect of the copper-palladium bimetallic perovskite and hydroxyethyl cellulose membrane, as detailed below: Figure 1 This is a graph showing the photocatalytic CO2 reduction product yields and CH4 selectivity of different metal halide perovskites. As can be seen from the graph, the lead-based perovskite Ce / Cs₂PbCl₄ obtained using the method and components of Comparative Example 1 exhibits low CO2 reduction product yields and CH4 selectivity, with CO and CH4 yields of only 2.6 and 1.71 μmol / g / h, respectively, and a CH4 selectivity of 72%. The copper-based perovskite Ce / Cs₂CuCl₄ obtained using the method and components of Comparative Example 2 shows improved CO2 reduction product yields and CH4 selectivity compared to Ce / Cs₂PbCl₄ obtained in Comparative Example 1, with CO and CH4 yields increasing to 7.31 and 7.36 μmol / g / h, respectively, and a CH4 selectivity of 80%. This demonstrates that Cu plays a crucial role in accelerating the multi-electron and proton transfer CO2 reduction process. For bimetallic halide perovskites, the CO2 reduction product yield of Ce / Cs2CuCl4-0.1Pd obtained in Example 2 was significantly higher than that of Ce / Cs2PbCl4, with CO and CH4 yields of 19.58 and 38.55 μmol / g / h, respectively, and CH4 selectivity increased to 89%. This demonstrates that doping Cs2CuCl4 with Pd can regulate the local electronic structure of Cu, thereby affecting CO2 adsorption and activation and improving the selectivity of the target product CH4.

[0024] Figure 2The graph shows the photocatalytic CO2 reduction product yield and CH4 selectivity of bimetallic halide perovskites doped with different proportions of Pd. As can be seen from the graph, the copper-based perovskite Ce / Cs₂CuCl₄ obtained by the method and components in Comparative Example 2 exhibits low CO2 reduction product yield and CH4 selectivity, with CO and CH4 reduction yields of 7.31 and 7.36 μmol / g / h, respectively, and a CH4 selectivity of 80%. In contrast, the three bimetallic perovskites Ce / Cs₂CuCl₄-0.05Pd, Ce / Cs₂CuCl₄-0.1Pd, and Ce / Cs₂CuCl₄-0.15Pd obtained in Examples 1-3 show significantly improved catalytic performance compared to Ce / Cs₂CuCl₄. The product yield and CH4 selectivity initially increase and then decrease with increasing Pd doping ratio. In Example 2, Ce / Cs2CuCl4-0.1Pd exhibited the best CO2 reduction performance, with CO and CH4 yields of 19.58 and 38.55 μmol / g / h, respectively, and CH4 selectivity increased to 89%. This demonstrates that Pd doping can modulate the local electronic structure of Cu in Cs2CuCl4 and improve the selectivity of the target product CH4.

[0025] Figure 3 This is a graph showing the CO reduction product yields and CH4 selectivity of Cs₂CuCl₄-0.1Pd bimetallic halide perovskite under different proton sources. As can be seen from the graph, the Cs₂CuCl₄-0.1Pd powder catalyst obtained in Comparative Example 3, with a small amount of H₂O as the proton source, exhibits low CO and CH₄ yields of only 3.49 and 1.03 μmol / g / h, respectively, and a CH₄ selectivity of only 54%. This is because lead halide perovskite has poor stability in H₂O, and the energy required for H₂O decomposition to generate *H is high, affecting its photocatalytic performance. In contrast, the hydroxyethyl cellulose-encapsulated Ce / Cs₂CuCl₄-0.1Pd metal halide perovskite obtained in Example 2 shows a significantly improved reduction yield, with CO and CH₄ yields of 19.58 and 38.55 μmol / g / h, respectively, and a CH₄ selectivity increased to 89%. This is because hydroxyethyl cellulose contains abundant hydroxyl groups, which are easier to decompose than H2O, thus providing sufficient protons for CO2 conversion and helping to improve CO2 reduction yield and CH4 selectivity.

[0026] Based on the analysis and comparison of the above embodiments and comparative examples, it can be seen that a single Cu site exhibits weak adsorption of CO2 molecules and poor selectivity for the target product CH4. Doping metal halide perovskite materials with Pd can modulate the local electronic structure of Cu sites, thereby affecting CO2 molecule adsorption and activation, and improving the yield of the target reduction product and the selectivity for the target product CH4. Furthermore, CO2 reduction using H2O as a proton source is constrained by the slow process of H2O decomposition providing protons. Using hydroxyethyl cellulose as a solid proton source, its abundant hydroxyl groups can participate in the CO2 catalytic reaction as protons, which is beneficial for the proton-electron coupling reaction and further improves the CH4 selectivity.

[0027] The above description is merely a specific embodiment of the present invention, but the scope of protection of the invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the invention.

Claims

1. A copper-palladium bimetallic perovskite material coated with a highly selective hydroxyethyl cellulose membrane for photocatalytic CO2 reduction to CH4, characterized in that: The material was prepared by reacting cesium chloride (CsCl), copper chloride (CuCl2), palladium chloride (PdCl2), dimethyl sulfoxide (DMSO), isopropanol (IPA), hydroxyethyl cellulose, and ethyl acetate. The preparation method of the copper-palladium bimetallic perovskite material coated with hydroxyethyl cellulose membrane is as follows: Step 1: Weigh out CsCl and CuCl2 and dissolve them in DMSO solvent, then stir with a magnetic stirrer for 1-5 hours; Step 2: Add a certain amount of PdCl2 to the perovskite precursor solution and continue stirring for 0.5-2 h. Then, add a certain amount of IPA antisolvent dropwise to the perovskite precursor solution. Sonicate for 0.5-3 h. The mass of PdCl2 added is 5-300 mg, and the amount of IPA is 5-80 mL. Step 3: After the reaction is complete, the precipitate is collected by centrifugation and washed with IPA 3-5 times. The obtained sample is dried in a vacuum drying oven at 60-100 ℃ for 4-20 h, and then the temperature is raised to 120-200 ℃ for 20-80 min to obtain copper-palladium bimetallic perovskite material. Step 4: Dissolve a certain amount of hydroxyethyl cellulose in ethyl acetate solvent, then add a certain amount of copper-palladium bimetallic perovskite material, and sonicate for 30-120 min; the mass of hydroxyethyl cellulose used is 0.2-2.0 g, the volume of ethyl acetate is 5-30 mL, and the mass of copper-palladium bimetallic perovskite material is 0.05-1 g. Step 5: Pour the obtained dispersion into a petri dish, place it in a glass container containing color-changing silica gel, and dry at room temperature for 5-24 hours; Step 6: After the cellulose membrane is completely dry, use tweezers to remove the membrane, thus obtaining the copper-palladium bimetallic perovskite material wrapped in hydroxyethyl cellulose membrane.

2. The copper-palladium bimetallic perovskite material coated with a hydroxyethyl cellulose membrane for photocatalytic CO2 reduction to CH4 as described in claim 1, characterized in that: In step 1, weigh out 30-100 mg of CsCl, 5-50 mg of CuCl2, and 1-5 mL of DMSO.

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