A si-doped cu-based perovskite oxide catalyst and a method for preparing the same

Abstract

The application discloses a Si-doped Cu-based perovskite oxide catalyst and a preparation method thereof, and belongs to the technical field of CO2 electrocatalysis, and comprises the following steps: grinding 2 mol of praseodymium oxide, 0.97 mol of copper oxide and 0.03 mol of silicon oxide into powders, then grinding the powders and zirconium beads and 100 ml of isopropyl alcohol after mixing, obtaining a precursor and pouring the precursor into a container, then filtering the zirconium beads in the precursor, performing drying, obtaining dry powders, performing calcination on the dry powders, and obtaining Pr2Cu 0.97 Si 0.03 O 4‑δ (PCSi 0。03 ). The Si-doped Cu-based perovskite catalyst is beneficial to the formation of Si-O-Cu bonds, and the Pr2Cu 0.97 Si 0.03 O 4‑δ (PCSi 0。03 ) has good thermodynamic stability and carbon dioxide adsorption capacity, and has very good electro-reduction performance on carbon dioxide in the application of CO2 electrocatalytic reduction.

Description

Technical Field

[0001] This invention belongs to the field of CO2 electrocatalysis technology, specifically relating to a Si-doped Cu-based perovskite oxide catalyst and its preparation method. Background Technology

[0002] CO2 electroreduction (CO2RR) is a green and pollution-free catalytic conversion technology for CO2. Since C2H4 is an important industrial raw material, the catalytic conversion of CO2 to C2H4 has high practical and economic value. However, most commonly used catalysts for the electrocatalytic conversion of CO2 to C2H4 are Cu-based catalysts. During the reaction, crystal reconstruction occurs, leading to low Faradaic efficiency and poor selectivity, limiting their large-scale application. Designing and preparing a class of highly selective, high Faradaic efficient copper-based catalysts is of great significance. Transition metals are inexpensive and represent a potential class of excellent electrocatalysts.

[0003] But transition metals affect H The high adsorption capacity of transition metals makes them more prone to hydrogen evolution reactions, reducing the selectivity of CO2 reduction products. Surface modification of transition metals can alter the adsorption strength for intermediate species, thereby improving their CO2 reduction capacity. Si-doped Cu-based perovskite catalysts exhibit high CO2 reduction capacity, with a Faradaic efficiency of approximately 51% for C2H4. However, research on perovskite catalysts in the CO2 field is still in its early stages, and there are no reports in the literature on controlling the CO2 reduction capacity of Cu-based catalysts by adjusting the Si-doping ratio of Cu-based perovskite. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a Si-doped Cu-based perovskite oxide catalyst and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A Si-doped Cu-based perovskite oxide catalyst, the catalyst having the chemical formula Pr₂Cu 0.97 Si 0.03 O 4-δ (PCSi) 0.03 ).

[0007] A method for preparing a Si-doped Cu-based perovskite oxide catalyst includes the following steps:

[0008] 2 mol of praseodymium oxide, 0.97 mol of copper oxide, and 0.03 mol of silicon oxide were ground into powder.

[0009] The powder is then mixed with zirconium beads and 100ml of isopropanol and ground to obtain the precursor, which is then poured into a container.

[0010] The zirconium beads in the precursor were then filtered and dried to obtain a dry powder.

[0011] The dried powder was calcined to obtain Pr₂Cu. 0.97 Si 0.03 O 4-δ (PCSi) 0.03 ).

[0012] Furthermore, the powder, zirconium beads, and isopropanol are added to a ball mill and ground at a high speed of 500 rpm.

[0013] Furthermore, the dried powder is calcined in a muffle furnace at 1000°C.

[0014] Application of a Si-doped Cu-based perovskite oxide catalyst in CO2 electrocatalysis.

[0015] The beneficial effects of this invention are:

[0016] 1. Using Si-doped Cu-based perovskite catalysts facilitates the formation of Si-O-Cu bonds.

[0017] 2. Pr2Cu 0.97 Si 0.03 O 4-δ (PCSi) 0.03 It has good thermodynamic stability and carbon dioxide adsorption capacity.

[0018] 3. Pr2Cu 0.97 Si 0.03 O 4-δ (PCSi) 0.03 It exhibits excellent electroreduction performance for carbon dioxide in CO2 electrocatalytic reduction applications. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The PC and PCSi prepared according to Examples 1, 2, 3 and 4 of this invention are examples of this invention. 0.01 PCSi 0.03 and PCSi 0.09 X-ray diffraction (XRD) pattern;

[0021] Figure 2 The PCSi prepared in Example 3 of this invention 0.03The Faraday efficiency diagram for catalysts used in the electroreduction reaction of CO2 to produce C2H4;

[0022] Figure 3 This is a comparison chart of the Faraday efficiency of the C2H4 catalyst products prepared in Examples 1, 2, 3, and 4 of this invention;

[0023] Figure 4 This invention is PCSi 0.03 Stability test graph at -1.0V vs. RHE. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] A Si-doped Cu-based perovskite oxide catalyst and its preparation method.

[0026] Example 1:

[0027] At room temperature, 2 mol of praseodymium oxide and 1 mol of copper oxide were added to a mortar and ground for 1 hour. After thorough grinding, the powder, zirconium beads, and 100 ml of isopropanol were added to a ball mill and ground at 500 rpm for 4 hours. After grinding, the precursor was poured into a beaker, the zirconium beads were filtered out, and then the powder was dried in an oven. The dried powder was placed in a crucible and calcined in a muffle furnace under air at 1000°C for 10 hours to obtain Pr₂CuO. 4-δ (PC).

[0028] Example 2

[0029] At room temperature, 2 mol of praseodymium oxide, 0.99 mol of copper oxide, and 0.01 mol of silicon oxide were added to a mortar and ground for 1 hour. After thorough grinding, the powder, zirconium beads, and 100 ml of isopropanol were added to a ball mill and ground at 500 rpm for 4 hours. After grinding, the precursor was poured into a beaker, the zirconium beads were filtered out, and then the mixture was dried in an oven. The resulting dry powder was placed in a crucible and calcined in a muffle furnace under air at 1000°C for 10 hours to obtain Pr₂Cu. 0.99 Si 0.01 O 4-δ (PCSi) 0.01 ).

[0030] Example 3

[0031] At room temperature, 2 mol of praseodymium oxide, 0.97 mol of copper oxide, and 0.03 mol of silicon oxide were added to a mortar and ground for 1 hour. After thorough grinding, the powder, zirconium beads, and 100 ml of isopropanol were added to a ball mill and ground at 500 rpm for 4 hours. After grinding, the precursor was poured into a beaker, the zirconium beads were filtered out, and then the mixture was dried in an oven. The resulting dry powder was placed in a crucible and calcined in a muffle furnace under air at 1000°C for 10 hours to obtain Pr₂Cu. 0.97 Si 0.03 O 4-δ (PCSi) 0.03 ).

[0032] Example 4

[0033] At room temperature, 2 mol of praseodymium oxide, 0.91 mol of copper oxide, and 0.09 mol of silicon oxide were added to a mortar and ground for 1 hour. After thorough grinding, the powder, zirconium beads, and 100 ml of isopropanol were added to a ball mill and ground at 500 rpm for 4 hours. After grinding, the precursor was poured into a beaker, the zirconium beads were filtered out, and then the mixture was dried in an oven. The resulting dry powder was placed in a crucible and calcined in a muffle furnace under air at 1000°C for 10 hours to obtain Pr₂Cu. 0.91 Si 0.09 O 4-δ (PCSi) 0.09 ).

[0034] The products obtained in the above embodiments were then subjected to CO2 reduction tests. The CO2 reduction test conditions in the above embodiments were: 0.5 mol KHCO3 electrolyte, potential scan range of -0.8 to -1.2 V (vs. RHE), and scan rate of 5 mV / s.

[0035] The following are the specific steps of the reduction test: Carbon paper coated with a catalyst was used as the working electrode, Ag / AgCl as the reference electrode, and graphite sheets as the auxiliary electrode. Different electrochemical techniques were employed to test the electrochemical performance of the material in an H-type electrolytic cell. The H-type electrolytic cell was separated by a Nafion-117 proton exchange membrane to prevent oxygen generated in the anode chamber from diffusing into the cathode chamber and oxidizing the reduction products. 25 mL of 0.5 M KHCO3 solution was added to each electrolytic chamber as the electrolyte solution. A Chenhua (CHI-660E) electrochemical workstation was used to test the material's electrochemical performance. All electrochemical experiments were conducted at room temperature. Before the electrochemical tests, CO2 (20 mL / min) or Ar was pre-purified for at least 30 min, firstly to saturate the KHCO3 solution, and secondly to eliminate interference from air inside the system.

[0036] Figure 1a represents the PC and PCSi prepared in Examples 1, 2, 3, and 4. 0.01 PCSi 0.03 and PCSi 0.09 X-ray diffraction (XRD) pattern.

[0037] Depend on Figure 1 The XRD patterns of a show that the injection peaks of all prepared catalysts are consistent with those of the PDF card, indicating that the prepared catalysts are all pure phases without other impurities.

[0038] Figure 1 b is a partial view of 30°~35° in the XRD of Examples 1, 2, 3 and 4.

[0039] Depend on Figure 1 The XRD pattern of b shows that the XRD pattern shifts to the right as the Si doping concentration increases. This indicates that Si has been successfully doped into the Cu-based perovskite, because according to the Scherrer equation, Si doping causes lattice compression, resulting in a shift to a higher angle, which is consistent with experimental results.

[0040] Figure 1 c represents the PCSi prepared in Example 3. 0.03 SEM image of the electrocatalyst.

[0041] Depend on Figure 1 Scanning electron microscopy (SEM) images reveal the morphology and structure of Cu-based perovskite oxides. The interconnect network consists of particles with sizes ranging from 500 to 700 nm, exhibiting good porosity on the surface.

[0042] Figure 1 di is the PCSi prepared in Example 3. 0.03 TEM image and elemental distribution diagram of the electrocatalyst.

[0043] Figure 1 d shows PCSi 0.03 The high-resolution transmission electron microscope (HR-TEM) image shows a lattice spacing of 0.282 nm, which is about 0.001 nm smaller than the (103) plane spacing calculated by XRD. This is consistent with the above analysis according to the Debye-Scherrer equation, which strongly confirms the doping of Si. Furthermore, the corresponding fast Fourier transform (FFT) pattern further reveals the selected area electron diffraction (SAED) pattern along the axis of the

[103] region. Figure 1 Image e~i shows high-angle annular dark-field scanning TEM (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS) mapping images, revealing a uniform distribution of all constituent elements, including Pr, Cu, Si, and O. This further confirms the successful incorporation of Si into the copper oxide lattice.

[0044] Figure 2 PCSi prepared in Example 3 0.03 The Faraday efficiency diagram for the catalyst used in the electroreduction reaction of CO2 to produce C2H4 is shown.

[0045] In detail, the products of CO2RR on the catalyst were found to be CO, CH4, and C2H4. Furthermore, H2 was also detected as a competing reaction between the hydrogen evolution reaction and the CO2 reduction reaction. With increasing applied potential, the FE% of CO decreased, while that of C2H4 increased and then decreased. One possible reason for the gradual increase is the CC coupling of CO at appropriate potentials, leading to the formation of C2H4. Meanwhile, H2 consistently dominated the products, with C2H4 only predominating at -1.0 V vs. RHE and -1.1 V vs. RHE, indicating that H2 is only suppressed at appropriate applied potentials, with a maximum FE% of 51.4% for C2H4 at -1.0 V with RHE.

[0046] As the applied potential increases, the FE of CO decreases, while that of C2H4 increases, and then decreases. C2H4 dominates at -1.0 V vs. RHE and -1.1 V vs. RH, indicating that H2 is suppressed only under appropriate applied potentials, with the maximum FE% of C2H4 being 51.4% at -1.0 V vs. RHE.

[0047] Figure 3 The chart shows a comparison of the Faraday efficiency of the C2H4 products prepared in Examples 1, 2, 3, and 4.

[0048] Compared with Examples 1 and 4, Example 3 showed the best CO2 reduction effect.

[0049] Using Si-doped Cu-based perovskite catalysts facilitates the formation of Si-O-Cu bonds. Under alkaline conditions, the Si-O bonds are readily affected by OH groups. - The nucleophilic attack of the anion generates a silanol Si-OH group. The electrolyte used is 0.5 M KHCO3 with a pH of 7.2, which is weakly alkaline. Therefore, the Gibbs free energies of the intermediates OCCOH-SiOH and OCCOH-Si were calculated. Further investigation revealed that if PCSO-SiOH is not... Formed in OCCO OCCOH-SiOH→ In the OCCOH step, the energy barrier increases to 2.10V, indicating that... The formation of OCCO → OCCOH-SiOH effectively improved efficiency, indicating OCCOH is more stable when adsorbed on SiOH than on Si. This may be due to... A Si-O-Cu bond is formed between the Oδ- of the OCCOH intermediate and PCSO. Then, a Si-O-Cu bond is introduced onto the Si surface. OH、 OCCOH and two O atoms form a very stable Si-O tetrahedral structure, which is more easily adsorbed. OCCOH- intermediate.

[0050] like Figure 4 As shown, for PCSi 0.03 To assess its stability, we conducted CO2RR tests over a longer period, with continuous electrolysis for 5 hours. We found that the Faraday efficiency of ethylene was approximately 50, demonstrating its good relative stability.

[0051] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0052] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A Si-doped Cu-based perovskite oxide catalyst, characterized in that, The catalyst has the chemical formula Pr₂Cu. 0.97 Si 0.03 O 4-δ ; The method for preparing the catalyst includes the following steps: 2 mol of praseodymium oxide, 0.97 mol of copper oxide, and 0.03 mol of silicon oxide were ground into powder; The powder is then mixed with zirconium beads and 100ml of isopropanol and ground to obtain the precursor, which is then poured into a container. The zirconium beads in the precursor were then filtered and dried to obtain a dry powder. The dried powder was calcined to obtain Pr₂Cu. 0.97 Si 0.03 O 4-δ .

2. The Si-doped Cu-based perovskite oxide catalyst according to claim 1, characterized in that, The powder, zirconium beads, and isopropanol were added to a ball mill and ground at high speed at 500 rpm.

3. The Si-doped Cu-based perovskite oxide catalyst according to claim 2, characterized in that, The dried powder was calcined in a muffle furnace at 1000°C.

4. The application of the Si-doped Cu-based perovskite oxide catalyst according to claim 1 in CO2 electrocatalysis.

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