Core-shell structure catalyst rich in interface, preparation method of core-shell structure catalyst and application of core-shell structure catalyst in electrocatalytic reduction of CO2
The PraInbOx catalyst prepared by solvent thermal synthesis and high-temperature calcination method solves the problem of cumbersome catalyst synthesis steps in the existing technology and achieves the effect of efficient electrocatalytic reduction of CO2, especially showing excellent performance in formic acid product selectivity and active potential.
Patent Information
- Application Number
- CN202510876246.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-09-19
Smart Images
Figure CN120666368A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of catalyst technology, and in particular relates to a PrInO x A catalyst and a preparation method thereof, as well as application of the catalyst in electrocatalytic reduction of CO2 conversion. Background Art
[0002] In this context, electrocatalytic carbon dioxide reduction technology (CO2RR) driven by renewable energy is attractive because it can achieve the dual functions of CO2 resource conversion and electrical energy storage. Current research focuses on constructing efficient electrocatalyst systems by precisely controlling the electronic structure and surface microenvironment of the catalyst, in order to achieve breakthroughs in key performance indicators such as Faraday efficiency, product selectivity and long-term stability. The intrinsic activity of the electrocatalytic reaction originates from the charge transfer characteristics of the catalyst surface and interface structure. Directed construction of functionalized active microregions through interface engineering has become a key strategy to improve catalytic performance. In addition, rare earth materials are mineral resources with great development potential in my country, with the advantages of wide distribution, rich reserves and complete variety. Among them, praseodymium oxides, as the oxide with the highest oxygen mobility among all undoped rare earth oxides, have great research space. Typical studies include scientific literature (Liu, J., Li, P., Jia, S. et al. Electrocatalytic CO2 hydrogenation to C 2+ alcohols catalyzed by
[0003] Pr–Cu oxide heterointerfaces. Nat. Synth 4, 730-743 (2025).) reported a step-by-step precipitation and calcination strategy to create Pr-Cu oxide heterointerfaces (Pr6O 11 -Cu-SS) catalyst, resulting in efficient CO2RR performance. Experimental and theoretical studies have shown that the performance of this catalyst is due to the 11 -The presence of Pr in Cu-SS 4+ / Pr 3+ structure, which can effectively stabilize Cu through a unique Pr-O-Cu bond δ+ / Cu 0 , and form a stable oxide heterogeneous interface. However, the catalyst synthesis method involves multiple steps of precipitation and calcination to complete.
[0004] In summary, how to design experiments, effectively simplify the synthesis steps and construct Pr-based catalysts with rich interfaces is of great significance for optimizing catalyst structure, revealing the structure-activity relationship in catalysts and clarifying the reaction mechanism of electrocatalytic reduction of CO2. Summary of the Invention
[0005] In view of the problems existing in the prior art, according to one aspect of the present invention, an object of the present invention is to provide a simple method of preparing a core-shell structure of Pr with a unique litchi-like and rich interface by solvent thermal synthesis combined with high temperature calcination treatment. a In b O x The catalyst, wherein the subscripts a and b are the molar ratios of Pr and In, respectively, for example, a:b is 0.1:10 to 10:0.1, and x is the molar ratio of O atoms allowed by chemical valence.
[0006] Preferably, a:b is 0.5:8 to 8:0.5, more preferably 0.1:2 to 2:1, and most preferably 1:1.
[0007] Preferably, the Pr a In b O x The catalyst particle size is 1 to 2 μm.
[0008] According to another aspect of the present invention, another object of the present invention is to provide the Pr a In b O x A method for preparing a catalyst, comprising the following steps:
[0009] Step 1) In precursor and Pr precursor are mixed in a mixed solution of isopropyl alcohol, glycerol and ultrapure water according to a certain molar ratio;
[0010] Step 2) The original mixed solution stirred evenly in step 1) was transferred and sealed in a stainless steel reactor lined with polytetrafluoroethylene, and placed in an oven for hydrothermal reaction at a temperature of 120 to 220°C for 6 to 24 hours. After the reaction was completed, the mixture was centrifuged to obtain a sample Pr a In b O x Precursor;
[0011] Step 3) Pr obtained in step 2) a In b O x The precursor powder sample was placed in a muffle furnace at 600 to 900 ° C for calcination to obtain the sample Pr a In b O x catalyst.
[0012] Preferably, the In precursor and Pr precursor described in step 1) are respectively selected from their nitrates, hydrochlorides, sulfates, phosphates, etc., preferably nitrates, more preferably In(NO3)3·6H2O and Pr(NO3)3·6H2O.
[0013] Preferably, the molar ratio of the In precursor to the Pr precursor in step 1) is 0.1:10 to 10:0.1, preferably 0.5:8 to 8:0.5, more preferably 0.1:2 to 2:1, more preferably 1:1.
[0014] Preferably, the mixed solution in step 1) is prepared by mixing isopropyl alcohol, glycerol and ultrapure water in a certain volume ratio, preferably 1:1:1 to 15:1:1, more preferably 15:3:1.
[0015] Preferably, the total concentration of the In precursor and the Pr precursor in step 1) is 0.5 mmol to 5 mmol, preferably 1 to 2 mmol, more preferably 2 mmol, and the molar ratio between the two is 1:1.
[0016] Preferably, in the hydrothermal reaction of step 2), the reaction temperature is preferably 180° C., and the reaction time is preferably 12 h.
[0017] Preferably, in step 3), the calcination temperature is 900° C. and the calcination time is 2 h.
[0018] According to another aspect of the present invention, another object of the present invention is to provide a a In b O x Catalyst working electrode.
[0019] According to another aspect of the present invention, another object of the present invention is to provide a method for preparing the working electrode, the preparation method comprising: a In b O x The catalyst material is mixed with isopropyl alcohol and Nafion solution and ultrasonically dispersed to obtain a mixed solution, and then the mixed solution is evenly coated on a carbon cloth and then dried to form the working electrode.
[0020] Preferably, in the preparation method of the working electrode, Pr a In b O x The ratio of catalyst material to isopropanol and Nafion solution is 6 mg:0.35 mL:0.07 mL.
[0021] Preferably, the Nafion solution is a 5 wt% perfluorosulfonic acid resin Nafion solution.
[0022] According to another aspect of the present invention, another object of the present invention is to provide a method for preparing formic acid from CO2 through an electrocatalytic reduction reaction, wherein the method uses the working electrode according to the present invention to perform the electrocatalytic reduction reaction.
[0023] Beneficial effects
[0024] According to the preparation method of the present invention, a Pr core-shell structure with a unique litchi-like and rich interface is obtained by combining a solvent thermal reaction with a high-temperature calcination method. a In b O x The catalyst exhibits excellent selectivity for formic acid production in the electrocatalytic reduction of CO2: high FE HCOO -Faraday efficiency (FE at -1.1V vs. RHE) HCOO-(max) =94.0%), and a wide high activity potential range (-0.7~-1.1V vs.RHE:FE HCOO ->80%). BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0026] Figure 1 The micron-sized spherical InO prepared in step 1) of Example 1 of the present invention x -Scanning electron micrograph of the precursor.
[0027] Figure 2 3 is a scanning electron microscope image of the In2O3-600, In2O3-700, In2O3-800, and In2O3-900 catalysts prepared in steps 1) and 2) of Example 1 of the present invention.
[0028] Figure 3 The PrO prepared in step 1) of Example 2 of the present invention x -Scanning electron micrograph of the precursor.
[0029] Figure 4 The Pr6O prepared in steps 1) and 2) of Example 2 of the present invention 11 -900 scanning electron microscope image and EDX element distribution map.
[0030] Figure 5 The micron-sized spherical PrInO prepared in step 1) of Example 3 of the present inventionx -Scanning electron micrograph of the precursor.
[0031] Figure 6 The lychee-shaped PrInO prepared in steps 1) and 2) of Example 3 of the present invention x Scanning electron microscope image of the -900 catalyst and a model diagram of the lychee-shaped structure.
[0032] Figure 7 The lychee-shaped PrInO prepared in steps 1) and 2) of Example 3 of the present invention x X-ray diffraction pattern of -900 catalyst.
[0033] Figure 8 The lychee-shaped PrInO prepared in steps 1) and 2) of Example 3 of the present invention x Transmission electron microscope image and EDX element distribution map of -900 catalyst.
[0034] Figure 9 The performance diagram of In2O3-600, In2O3-700, In2O3-800 and In2O3-900 catalysts prepared in steps 1) and 2) of Example 1 of the present invention for electrocatalytic reduction of CO2 (HCOO - Faradaic efficiency diagram of the product).
[0035] Figure 10 In2O3-900, PrInO prepared in steps 1) and 2) of Examples 1 and 3 of the present invention x -900 catalyst for electrocatalytic reduction of CO2 performance diagram (HCOO - , CO, and H2 products).
[0036] Figure 11 The PrInO prepared in steps 1) and 2) of Example 3 of the present invention x -900 catalyst for electrocatalytic reduction of CO2 performance diagram (HCOO - , CO, and H2 products).
[0037] Figure 12 3 are scanning electron microscope images of the In2O3-isopropanol precursor (a) and the In2O3-isopropanol-900 catalyst (b) prepared in steps 1) and 2) of Example 4 of the present invention.
[0038] Figure 13 3 are scanning electron microscope images of the In2O3-water precursor (a) and the In2O3-water-900 catalyst (b) prepared in steps 1) and 2) of Example 5 of the present invention.
[0039] Figure 14The PrInO prepared in steps 1) and 2) of Example 6 of the present invention x -Isopropyl alcohol precursor (a), PrInO x -Scanning electron micrograph of isopropyl alcohol-based-900 catalyst (b).
[0040] Figure 15 The PrInO prepared in steps 1) and 2) of Example 7 of the present invention x -Aqueous precursor, PrInO x -Scanning electron micrograph of the aqueous-900 catalyst (b).
[0041] Figure 16 In2O3-isopropanol-900, In2O3-water-900, PrInO x -Isopropyl alcohol-900, PrInO x -Water system-900 Four catalysts for electrocatalytic reduction of CO2 performance diagram (HCOO - Faradaic efficiency diagram of the product). DETAILED DESCRIPTION
[0042] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Prior to the description, it should be understood that the terms used in the specification and the appended claims are not to be construed as limited to their general and dictionary meanings, but rather should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present invention, based on the principle that allows the inventor to appropriately define the terms for the best interpretation. Therefore, the description herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the present invention. It should be understood that other equivalent implementations and modifications may be made without departing from the spirit and scope of the present invention.
[0043] As used herein, the terms "comprises," "includes," "has," "contains" or any other similar terms are open conjunctions that are intended to cover non-exclusive inclusions. For example, a composition or article containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or article. In addition, unless expressly stated to the contrary, the term "or" refers to an inclusive "or" rather than an exclusive "or." For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist). In addition, as used herein, the terms "comprises," "includes," "has," and "contains" should be interpreted as specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as "consisting of" and "consisting essentially of."
[0044] Throughout this document, all features or conditions defined as numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values within those ranges, particularly integer values. For example, a description of a range "1 to 8" should be considered to specifically disclose all possible subranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, and so forth, particularly those defined by all integer values, and should be considered to specifically disclose individual values within those ranges such as 1, 2, 3, 4, 5, 6, 7, and 8. Unless otherwise indicated, the foregoing interpretation applies to all of the present disclosure, regardless of whether the ranges are comprehensive or not.
[0045] If a quantity or other value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that all ranges consisting of any upper limit or preferred value of the range and any lower limit or preferred value of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, when a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.
[0046] In this document, numerical values should be understood to have the accuracy of the number of significant digits of the numerical value, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.
[0047] In the preparation method according to the present invention, In(NO3)3·6H2O and Pr(NO3)3·6H2O are used as reaction raw materials. In the presence of isopropanol, glycerol and ultrapure water, In(NO3)3·6H2O is reacted with Pr(NO3)3·6H2O. 3+ With Pr 3+ Participating in the coordination can form a micron-sized spherical structure precursor with a smooth surface (denoted as PrInO x -precursor). Under high temperature calcination, based on the process of different degrees of crystal growth, merging and growth, the smooth surface presents granular protrusions, and finally forms PrInO with rich interface and unique litchi-like core-shell structure. x If only In(NO3)3·6H2O or Pr(NO3)3·6H2O is added as a single raw material, it is difficult to control the morphology of the litchi-like core-shell structure.
[0048] In addition, unless otherwise specified, the reagents and solvents disclosed below were purchased from Sinopharm Group (Shanghai trial, analytical grade), and ultrapure water was homemade in the laboratory (>18 MΩ*cm); the liquid product of the electrocatalytic reduction of CO2, formic acid, was qualitatively and quantitatively analyzed by high performance liquid chromatography (HPLC, model UItimate3000), and the purity was calculated as the area % of HPLC; the gaseous products, such as carbon monoxide and hydrogen, were qualitatively and quantitatively analyzed by gas chromatograph (GC, Shandong Huifen HF-901A); the structural composition of the catalyst was characterized by powder X-ray diffractometer (Bruker D8 Advance); the morphology and elemental distribution were characterized by cold field emission scanning electron microscopy (SEM, Hitachi S-4800) and high-resolution transmission electron microscopy system (TEM, JEM-F200).
[0049] The following examples are merely examples of embodiments of the present invention and do not constitute any limitation thereto. Those skilled in the art will appreciate that modifications without departing from the spirit and scope of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are commercially available products.
[0050] Example 1
[0051] 1) 2 mmol of In(NO3)3·6H2O was fully dissolved in a mixed solution containing 45 mL of isopropanol, 9 mL of glycerol, and 3 mL of ultrapure water. The mixture was encapsulated in a 100 mL stainless steel reactor lined with polytetrafluoroethylene and placed in a 180°C oven for hydrothermal reaction for 12 h. After the reaction, the solution was centrifuged, washed, and dried to obtain the precipitate, which was InO x - Precursors;
[0052] 2) Weigh the InO in 1) above x -The precursor was placed in a muffle furnace at different temperatures (600, 700, 800, 900°C) and calcined for 2 hours. The obtained catalysts were recorded as In2O3-600, In2O3-700, In2O3-800, and In2O3-900.
[0053] Example 2
[0054] 1) 2 mmol of Pr(NO3)3·6H2O was fully dissolved in a mixed solution containing 45 mL of isopropanol, 9 mL of glycerol, and 3 mL of ultrapure water, encapsulated in a 100 mL stainless steel reactor lined with polytetrafluoroethylene, and placed in a 180°C oven for hydrothermal reaction for 12 hours. After the reaction, the solution was centrifuged, washed, and dried to obtain a precipitate of micron-sized spherical PrO x - Precursors;
[0055] 2) Weigh the PrO in 1) above x -The precursor was calcined in a muffle furnace at 900 ° C for 2 h and recorded as Pr6O 11 catalyst.
[0056] Example 3
[0057] 1) 1 mmol of In(NO3)3·6H2O and 1 mmol of Pr(NO3)3·6H2O were fully dissolved in a mixed solution containing 45 mL of isopropanol, 9 mL of glycerol, and 3 mL of ultrapure water, and the mixture was encapsulated in a 100 mL stainless steel reactor lined with polytetrafluoroethylene and placed in a 180°C oven for hydrothermal reaction for 12 h. After the reaction, the solution was centrifuged, washed, and dried to obtain a precipitate of micron-sized spherical PrInO x Precursor;
[0058] 2) Weigh the PrInO in 1) above x The precursor was calcined in a muffle furnace at 900 °C for 2 h and was recorded as PrInO x -900 catalyst.
[0059] Example 4
[0060] 1) 2 mmol of In(NO3)3·6H2O was fully dissolved in 57 mL of isopropanol solution, encapsulated in a 100 mL stainless steel reactor lined with polytetrafluoroethylene, and placed in a 180°C oven for hydrothermal reaction for 12 h. After the reaction, the solution was centrifuged, washed, and dried to obtain a precipitate, which was recorded as the In2O3-isopropanol precursor.
[0061] 2) The In2O3-isopropanol precursor prepared in 1) was weighed and placed in a muffle furnace at 900°C for calcination for 2 h, which was recorded as In2O3-isopropanol-900 catalyst.
[0062] Example 5
[0063] 2) 2 mmol of In(NO3)3·6H2O was fully dissolved in 57 mL of ultrapure water, encapsulated in a 100 mL stainless steel reactor lined with polytetrafluoroethylene, and placed in a 180°C oven for a hydrothermal reaction for 12 h. After the reaction, the solution was centrifuged, washed, and dried to obtain a precipitate, which was recorded as the In2O3-water precursor.
[0064] 2) The In2O3-water precursor prepared in 1) was weighed and placed in a muffle furnace at 900°C for calcination for 2 h, which was recorded as In2O3-water-900 catalyst.
[0065] Example 6
[0066] 3) 1 mmol of In(NO3)3·6H2O and 1 mmol of Pr(NO3)3·6H2O were fully dissolved in 57 mL of isopropanol solution, encapsulated in a 100 mL stainless steel reactor lined with polytetrafluoroethylene, and placed in a 180°C oven for hydrothermal reaction for 12 h. After the reaction, the solution was centrifuged, washed, and dried to obtain a precipitate, which was recorded as PrInO x -Isopropyl alcohol-based precursor;
[0067] 2) Weigh the PrInO in 1) above x -Isopropanol precursor was calcined in a muffle furnace at 900℃ for 2h and recorded as PrInO x -Isopropyl alcohol-900 catalyst.
[0068] Example 7
[0069] 1) 1 mmol of In(NO3)3·6H2O and 1 mmol of Pr(NO3)3·6H2O were fully dissolved in 57 mL of ultrapure water, encapsulated in a 100 mL stainless steel reactor lined with polytetrafluoroethylene, and placed in a 180°C oven for hydrothermal reaction for 12 h. After the reaction, the solution was centrifuged, washed, and dried to obtain a precipitate, which was recorded as PrInO x -Aqueous precursors;
[0070] 2) Weigh the PrInO in 1) above x The aqueous precursor was calcined in a muffle furnace at 900 °C for 2 h and recorded as PrInO x -Water-900 catalyst.
[0071] Test Example 1
[0072] In2O3-600 or In2O3-700 or In2O3-800 or In2O3-900 or Pr6O prepared according to Examples 1-3 11 or PrInO x Catalyst materials, In2O3-isopropanol system-900, In2O3-water system-900, PrInO x -Isopropyl alcohol-900, PrInO x -Aqueous-900 was mixed with isopropyl alcohol and Nafion solution and ultrasonically dispersed to obtain a mixed solution. The mixed solution was then evenly coated on a carbon cloth and dried to form a working electrode. The ratio of catalyst material to isopropyl alcohol and Nafion solution was 6 mg:0.35 mL:0.07 mL. The Nafion solution was a 5 wt% perfluorosulfonic acid resin Nafion solution.
[0073] The electrocatalytic reduction of CO2 was carried out in a double-chamber H-type electrolytic cell. The electrolytic cell consists of a cathode reaction chamber and an anode reaction chamber, and the two chambers are separated by a Nafion N117 proton exchange membrane. The catalyst activity was evaluated using a three-electrode system and a constant potential electrolysis method. The three electrodes were connected to a CHI660E electrochemical workstation. The platinum electrode clamp fixed the working electrode prepared above and the saturated KCl-filled Ag / AgCl electrode was placed in the cathode chamber as a reference electrode. A Pt sheet (1×1 cm 2 ) electrode is placed in the anode chamber as a reference electrode. The anode and cathode chambers are each filled with 25 mL of 0.5 M KHCO3 as the electrolyte. Before the start of the electrocatalytic reaction, high-purity CO2 (99.999%) gas is continuously introduced into the cathode working chamber for 30 minutes to remove oxygen from the electrolytic cell and saturate the electrolyte with CO2. During the electrocatalytic reaction, CO2 is continuously and constantly introduced at a flow rate of 30 mL / min. The electrocatalytic reduction of CO2 reaction occurs on the working electrode in the cathode chamber, and the electrolysis reaction of water occurs on the counter electrode in the anode chamber. After 30 minutes of electrolysis at each potential, the liquid product is sampled and analyzed, and the gaseous product is automatically sampled and analyzed every 10 minutes. Figure 9 The performance diagram of the four catalysts In2O3-600, In2O3-700, In2O3-800 and In2O3-900 prepared in Example 1 of the present invention for electrocatalytic reduction of carbon dioxide (HCOO - Faradaic efficiency diagram of the product, FE HCOO -), it can be seen from the figure that with the increase of calcination temperature (600-900℃), the FE of In2O3 catalyst HCOO - also gradually increases. It can be seen from the figure that the CO2RR performance of In2O3-900 catalyst is the best, reaching a maximum of 90.0% at -1.0V vs.RHE potential; combined with Figure 2 The corresponding SEM characterization results in the figure indicate that the calcination temperature is a necessary condition to drive the grain growth-contact-formation of grain boundaries, and as the number of grain boundaries increases, the FE HCOO - gradually increases, thus confirming the structure-activity relationship between the number of grain boundaries and CO2RR performance. Figure 10 The present invention adopts In2O3-900 prepared by Examples 1 and 3 and PrInO x -900 catalyst performance for electrocatalytic reduction of carbon dioxide (HCOO - , CO, H2 products Faraday efficiency diagram), from the figure we can see that PrInO x -900 FE HCOO -A significant improvement was achieved, reaching a maximum value of 94.0% at a potential of -1.1 V vs. RHE, which was attributed to the unique lychee-like core-shell structure constructed by Pr incorporation. Figure 11PrInO x Performance diagram of the -900 catalyst for electrocatalytic reduction of CO2, HCOO removal - There are no other products except CO and H2. The sum of the Faraday efficiencies of the three products is close to 100%, which is within the allowable error range. Figure 16 The present invention adopts In2O3-isopropanol system-900, In2O3-water system-900, PrInO x -Isopropyl alcohol-900, PrInO x -Water-900 Performance diagram of four catalysts for electrocatalytic reduction of carbon dioxide (HCOO - Faraday efficiency diagram of the product), it can be seen from the figure that FE HCOO - poor, with a maximum of no more than 40%. In summary, the mixed solution containing isopropanol, glycerol and ultrapure water is the key to preparing the catalyst with rich interface and high CO2RR activity.
[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.
Claims
1. A core-shell structure of Pr with a litchi-like rich interface a In b O x The catalyst, wherein the subscripts a and b are the molar ratios of Pr and In, respectively, for example, a:b is 0.1:10 to 10:0.1, and x is the molar ratio of O atoms allowed by chemical valence.
2. The catalyst according to claim 1, characterized in that Preferably, a:b is 0.5:8 to 8:0.5, more preferably 0.1:2 to 2:1, most preferably 1:1; Preferably, the Pr a In b O x The catalyst particle size is 1 to 2 μm.
3. The method for preparing the catalyst according to claim 1 or 2, comprising the steps of: Step 1) In precursor and Pr precursor are mixed in a mixed solution of isopropyl alcohol, glycerol and ultrapure water according to a certain molar ratio; Step 2) The original mixed solution stirred evenly in step 1) was transferred and sealed in a stainless steel reactor lined with polytetrafluoroethylene, and placed in an oven for hydrothermal reaction at a temperature of 120 to 220°C for 6 to 24 hours. After the reaction was completed, the mixture was centrifuged to obtain a sample Pr a In b O x Precursor; Step 3) Pr obtained in step 2) a In b O x The precursor powder sample was placed in a muffle furnace at 600 to 900 ° C for calcination to obtain the sample Pr a In b O x catalyst.
4. The preparation method according to claim 3, characterized in that Preferably, the In precursor and Pr precursor described in step 1) are respectively selected from their nitrates, hydrochlorides, sulfates, phosphates, etc., preferably nitrates, more preferably In(NO3)3·6H2O and Pr(NO3)3·6H2O; Preferably, the molar ratio of the In precursor to the Pr precursor in step 1) is 0.1:10 to 10:0.1, preferably 0.5:8 to 8:0.5, more preferably 0.1:2 to 2:1, more preferably 1:1; Preferably, the mixed solution in step 1) is prepared by mixing isopropyl alcohol, glycerol and ultrapure water in a certain volume ratio, preferably 1:1:1 to 15:1:1, more preferably 15:3:1; Preferably, the total concentration of the In precursor and the Pr precursor in step 1) is 0.5 mmol to 5 mmol, preferably 1 to 2 mmol, more preferably 2 mmol, and the molar ratio between the two is 1:
1.
5. The preparation method according to claim 3, characterized in that Preferably, in the hydrothermal reaction of step 2), the reaction temperature is preferably 180° C., and the reaction time is preferably 12 h.
6. The preparation method according to claim 3, characterized in that Preferably, in step 3), the calcination temperature is 900° C. and the calcination time is 2 h.
7. A method comprising preparing a Pr according to claim 1 or 2. a In b O x Catalyst working electrode.
8. The method for preparing a working electrode according to claim 7, comprising: The Pr according to claim 1 or 2 a In b O x The catalyst material is mixed with isopropyl alcohol and Nafion solution and ultrasonically dispersed to obtain a mixed solution, and then the mixed solution is evenly coated on a carbon cloth and then dried to form the working electrode.
9. The method for preparing a working electrode according to claim 8, wherein: In the preparation method of the working electrode, Pr a In b O x The ratio of catalyst material to isopropanol and Nafion solution is 6 mg:0.35 mL:0.07 mL; Preferably, the Nafion solution is a 5 wt% perfluorosulfonic acid resin Nafion solution.
10. A method for preparing formic acid from CO2 through an electrocatalytic reduction reaction, wherein the method uses the working electrode according to claim 7 to perform the electrocatalytic reduction reaction.