Preparation method and application of bismuth trioxide anchored metal-organic framework catalyst

Abstract

The invention relates to a preparation method and application of a bismuth trioxide anchored metal-organic framework catalyst, belongs to the field of electrode materials for catalyzing reduction of carbon dioxide, and particularly relates to a method for constructing an MOF confined Bi catalyst through a subject-object synthesis strategy by using a metal-organic framework material (MOF: PCN-222) with a clear structure and coordination as a carrier. And high-activity and high-stability electrocatalytic CO2 reduction is realized. According to the present invention, the reaction activity of the catalyst added with different Bi (NO3) 3.5 H2O ratios is compared through the electrochemical test, the final product Bi2O3 (at) PCN-222-2 sample has the optimal performance, the HCOOH Faraday efficiency can achieve 89.42% in the carbon dioxide saturated 0.005 M H2SO4 solution and the 0.5 M K2SO4 solution at the-1.8 V vs.RHE potential, and the HCOOH partial current density can achieve-268.7 mA cm <-2 >. The Bi2O3-coated PCN-222-2 catalyst material prepared by the method has an extremely high industrial application prospect in electroreduction of carbon dioxide, and can be widely applied to the field of electroreduction of carbon dioxide electrochemical energy storage devices.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalytic carbon dioxide reduction, and relates to a preparation method and application of a porphyrin metal-organic framework catalyst. BACKGROUND

[0002] Electrocatalytic CO2 reduction can further convert CO2 into carbon-containing chemicals by using electric energy at normal temperature and pressure, and has the advantages of mild reaction conditions, controllable products and simple device, and is one of the most promising CO2 conversion technologies. Therefore, the application uses a metal-organic framework material (MOF: PCN-222) with clear structure and coordination as a carrier, and constructs a Bi2O3@PCN-222 catalyst through a host-guest synthesis strategy to realize high-activity and high-stability electrocatalytic CO2 reduction. In a 0.005M H2SO4 and 0.5M K2SO4 solution saturated with carbon dioxide, the HCOOH faradic efficiency can reach 89.42% at a potential of-1.8V vs.RHE, and the highest HCOOH partial current density can reach-268.7mA cm-2. -2 .

[0003] Chinese patent CN102180517A discloses a method for producing bismuth trioxide by using bismuth hydroxide. The bismuth hydroxide is placed in a sodium hydroxide solution containing bismuth trioxide, and is gradually heated to convert the bismuth hydroxide into bismuth trioxide, and finally washed to obtain the product. However, the preparation method has many procedures and a complex process, and the morphology of the synthesized bismuth trioxide cannot be determined. The application discloses a preparation method and application of a Bi2O3@PCN-222 catalyst, which has excellent macroscopic morphology, and has the characteristics of mild synthesis conditions and easy realization, and can be well applied to the design and preparation field of metal catalysts. SUMMARY

[0004] The application provides a Bi2O3@PCN-222 catalyst and a preparation method thereof, which comprises the following steps:

[0005] (1) A certain stoichiometric ratio of zirconium oxychloride octahydrate and tetrakis(4-carboxyphenyl)porphyrin is dissolved in N,N-dimethylformamide, and then difluoroacetic acid is added after stirring.

[0006] (2) The uniformly stirred solution in (1) is added to a high-pressure reaction kettle, and then placed in an oven, and reacted in a 120℃ oven for 3h.

[0007] (3) After the reaction kettle in step (2) is cooled to room temperature, the reaction product is washed with deionized water and anhydrous ethanol, respectively.

[0008] (4) The washed product in step (3) is placed in a vacuum drying box at 60℃ and dried for 5h to obtain a MOF precursor.

[0009] (5) The MOF precursor obtained in (4) and a soluble bismuth salt are dissolved in N,N-dimethylformamide and stirred and dissolved.

[0010] (6) The solution stirred uniformly in (5) is added to a high-pressure reaction kettle, placed in an oven, and reacted for 3h in a 120°C oven.

[0011] (7) After the reaction kettle of step (6) is cooled to room temperature, the reaction product is washed with deionized water and anhydrous ethanol, and dried in a vacuum drying oven at 60°C for 5h to obtain Bi2O3@PCN-222.

[0012] Compared with the prior method, the Bi2O3@PCN-222 material prepared by the above method has the following advantages:

[0013] (1) The raw materials of the method are cheap and easy to obtain, the reaction conditions are simple and easy to control, and the method is environmentally friendly and non-polluting.

[0014] (2) The Bi2O3@PCN-222 material prepared by the method can promote the reduction of carbon dioxide to formic acid, and when the current density is -268.7mA cm -2 , the HCOOH faradic efficiency can reach 89.42%.

[0015] (3) The main product of the Bi2O3@PCN-222 material prepared by the method in the cathode solution is formic acid, which is easy to separate and extract from the electrolyte. High current density and product conversion rate can be achieved at a lower potential. Due to the above characteristics, the Bi2O3@PCN-222 material prepared by the method has a very high industrial application prospect for the electro-reduction of carbon dioxide, and can be widely used in the field of electrochemical energy storage devices for the electro-reduction of carbon dioxide. BRIEF DESCRIPTION OF DRAWINGS

[0016] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the following drawings:

[0017] Figure 1 The scheme diagram of the Bi2O3@PCN-222 catalyst material prepared in Examples 1, 2 and 3 of the present application.

[0018] Figure 2 a is the SEM scanning electron microscope graph of the PCN-222 catalyst material prepared in Example 1 of the present application. Figure 2 b is the SEM scanning electron microscope graph of the Bi2O3@PCN-222-1 catalyst material prepared in Example 2 of the present application. Figure 2c is the SEM scanning electron micrograph of the Bi2O3@PCN-222-2 catalyst material prepared in Example 3 of the application. Figure 2 d is the SEM scanning electron micrograph of the Bi2O3@PCN-222-3 catalyst material prepared in Example 4 of the application.

[0019] Figure 3 The XRD comparison chart of the PCN-222, Bi2O3@PCN-222-1, Bi2O3@PCN-222-2, Bi2O3@PCN-222-3 and commercial Bi2O3 catalyst materials prepared in Examples 1, 2, 3 and 4 of the application.

[0020] Figure 4 a is the XPS peak separation chart of N 1s of Examples 1, 3. Figure 4 b is the XPS peak separation chart of O 1s of Examples 1, 3 and commercial Bi2O3. Figure 4 c is the XPS peak separation chart of Zr 3d of Examples 1, 3. Figure 4 d is the XPS peak separation chart of Bi 4f of Examples 3 and commercial Bi2O3.

[0021] Figure 5 The LSV test activity comparison chart of the PCN-222, Bi2O3@PCN-222-1, Bi2O3@PCN-222-2, Bi2O3@PCN-222-3 and commercial Bi2O3 catalyst materials prepared in Examples 2, 3 and 4 of the application.

[0022] Figure 6 The Faraday efficiency chart of the products of the electrocatalytic reduction of carbon dioxide of the Bi2O3@PCN-222-2 catalyst material prepared in Example 3 of the application.

[0023] Figure 7 The partial current density chart of the HCOOH product of the Bi2O3@PCN-222 catalyst material prepared in Examples 2, 3 and 4 of the application by adding Bi(NO3)3·5H2O in different proportions.

[0024] Figure 8 The AC impedance chart of the Bi2O3@PCN-222 catalyst material prepared in Examples 2, 3 and 4 of the application by adding Bi(NO3)3·5H2O in different proportions.

[0025] Figure 9 The electro-reduction stability curve comparison chart of the Bi2O3@PCN-222-2 catalyst material prepared in Example 3 of the application. Specific implementation method

[0026] In order to make the technical solutions and advantages of the present application clearer, the present application will be described in detail below in combination with the drawings and examples. It should be noted that the following examples are only used to explain the present application and should not be used to limit the present application.

[0027] Example 1

[0028] Zirconium oxychloride octahydrate 150 mg and tetra(4-carboxyphenyl)porphyrin 27.8 mg were weighed and dissolved in 64 ml of N,N-dimethylformamide. After stirring uniformly, 1 ml of difluoroacetic acid was added, and stirring was continued. Subsequently, the mixture was transferred into a 100 ml high-pressure reaction kettle. The high-pressure reaction kettle was sealed and placed in an oven for reaction at 120°C for 24 hours. After cooling to room temperature, the product was washed with N,N-dimethylformamide and water, respectively, and dried in a vacuum drying box (drying at 60°C for 5 h) to obtain a dark purple PCN-222 powder.

[0029] Example 2

[0030] 50 mg of synthesized PCN-222 and 60 mg of Bi(NO3)3·5H2O were added to 20 ml of N,N-dimethylformamide solution and stirred for 40 min. Subsequently, the mixture was transferred into a 100 ml high-pressure reaction kettle. The high-pressure reaction kettle was sealed and placed in an oven for reaction at 120°C for 24 hours. After cooling to room temperature, the product was washed with N,N-dimethylformamide and water, respectively, and dried in a vacuum drying box (drying at 60°C for 5 h) to obtain a Bi2O3@PCN-222-1 powder.

[0031] Example 3

[0032] 50 mg of synthesized PCN-222 and 80 mg of Bi(NO3)3·5H2O were added to 20 ml of N,N-dimethylformamide solution and stirred for 40 min. Subsequently, the mixture was transferred into a 100 ml high-pressure reaction kettle. The high-pressure reaction kettle was sealed and placed in an oven for reaction at 120°C for 24 hours. After cooling to room temperature, the product was washed with N,N-dimethylformamide and water, respectively, and dried in a vacuum drying box (drying at 60°C for 5 h) to obtain a Bi2O3@PCN-222-2 powder.

[0033] Example 4

[0034] Synthesized 50 mg of PCN-222 and 100 mg of Bi(NO3)3·5H2O were added to a 20 ml solution of N,N-dimethylformamide, stirred for 40 min, and then transferred to a 100 ml high-pressure reaction kettle. The high-pressure reaction kettle was sealed, placed in an oven, and reacted at 120°C for 24 hours. After cooling to room temperature, the product was washed with N,N-dimethylformamide and water, and dried in a vacuum drying box (60°C for 5 h) to obtain a Bi2O3@PCN-222-3 powder.

[0035] Experimental Example

[0036] (1) SEM transmission electron microscope analysis

[0037] The catalyst prepared in Example 1 was subjected to SEM scanning electron microscope analysis, and the results are shown in Figure 2 a.

[0038] The catalyst prepared in Example 2 was subjected to SEM scanning electron microscope analysis, and the results are shown in Figure 2 b.

[0039] The catalyst prepared in Example 3 was subjected to SEM scanning electron microscope analysis, and the results are shown in Figure 2 c.

[0040] The catalyst prepared in Example 4 was subjected to SEM scanning electron microscope analysis, and the results are shown in Figure 2 d.

[0041] As can be seen from Figure 2 a, the PCN-222 precursor prepared in the present application is a spindle.

[0042] As can be seen from Figure 2 b, the Bi2O3@PCN-222-1 sample prepared in the present application presents a spindle structure, and a small amount of particles exist on the surface.

[0043] As can be seen from Figure 2 c, the Bi2O3@PCN-222-2 catalyst sample prepared in the present application presents a spindle structure, and a certain amount of particles exist on the surface.

[0044] As can be seen from Figure 2 d, the Bi2O3@PCN-222-3 catalyst sample prepared in the present application presents a spindle structure, and a large amount of particles exist on the surface.

[0045] (2) XRD analysis

[0046] The catalysts prepared in Examples 1, 2, 3, 4 and a commercial Bi2O3 catalyst were subjected to XRD comparative analysis, and the XRD patterns of the obtained catalysts are shown in Figure 3As shown, Examples 2, 3, and 4 show the presence of both PCN-222 and Bi2O3. Peaks at 7.06° and 9.71° are attributed to PCN-222. Peaks at 28.34°, 32.84°, 47.12°, and 55.91° are identical to those of Bi2O3 (PDF#76-2478) and also coincide with commercial Bi2O3 peak positions. This demonstrates the presence of both PCN-222 and Bi2O3 in the final product.

[0047] (3) XPS analysis

[0048] Examples 1 and 3 and commercial Bi2O3 catalysts were tested by X-ray photoelectron spectroscopy (XPS) to study the surface elemental composition and chemical state of the catalysts.

[0049] Figure 4 a is the XPS peak diagram of N 1s of Examples 1 and 3.

[0050] Figure 4 b is the XPS peak diagram of O 1s of Examples 1, 3, and commercial Bi2O3.

[0051] Figure 4 c is the XPS peak diagram of Zr 3d in Examples 1 and 3.

[0052] Figure 4 d is the XPS peak diagram of Bi4f of commercial Bi2O3 in Example 3.

[0053] like Figure 4 As shown, it can be seen from the XPS spectrum that Bi2O3@PCN-222-2 contains four element peaks of N, O, Zr and Bi, and Bi2O3@PCN-222-2 contains Zr element peaks and Bi element peaks, which proves the successful introduction of PCN-222 and Bi2O3.

[0054] (4) Electroreduction of carbon dioxide test

[0055] Electrode materials prepared in Examples 2, 3, and 4 were used for carbon dioxide electroreduction testing. The resulting Bi2O3@PCN-222 catalyst was prepared by mixing 7 mg of the catalyst sample with 950 μL of isopropanol. Ultrasonication was performed for 30 minutes until completely dissolved, followed by the addition of 50 μL of Nafion as a binder. Ultrasonication was then repeated for approximately 20 minutes to obtain a homogeneous solution. 100 μL of the homogeneous solution was then dripped four times onto a 0.5 x 2 cm2 area in the center of a piece of carbon paper. After drying under infrared light, electrochemical testing was performed.

[0056] The electrocatalytic CO2RR test adopts a gas diffusion electrode flow cell device: the counter electrode is a platinum sheet, the reference electrode is Ag / AgCl, and the carbon paper loaded catalyst is used as the working electrode. Regarding the experimental data processing process, the potential is converted into the reversible hydrogen electrode (RHE) potential according to the formula E (vs. RHE) = E (vs. Ag / AgCl) + 0.20 V + 0.0591 V x pH. The CO2 gas flow used for each group of samples for electrochemical testing is 20 mL min -1 , and the results are shown in Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 and Figure 9 .

[0057] As can be seen from Figure 5 , the starting potential of the Bi2O3@PCN-222-2 catalyst prepared in the present application is more positive, and at a potential of -1.8 V vs. RHE, the current density of the Bi2O3@PCN-222-2 sample is as high as -316.78 mA cm -2 .

[0058] As can be seen from Figure 6 , the Bi2O3@PCN-222-2 catalyst prepared in the present application almost reduces CO2 to HCOOH, and in a wide potential range of -1.1 V to -1.8 V vs. RHE, the faradic efficiency of HCOOH is maintained at more than 85%.

[0059] As can be seen from Figure 7 , the Bi2O3@PCN-222-2 catalyst prepared in the present application has the highest HCOOH partial current density, and the current density of the sample is as high as -268.7 mA cm -2 , indicating that the sample has excellent single product catalytic activity.

[0060] As can be seen from Figure 8 , the proportion of the Bi2O3@PCN-222-2 catalyst prepared in the present application has a certain degree of influence on the conductivity of the catalyst itself.

[0061] As can be seen from Figure 9 , the Bi2O3@PCN-222-2 catalyst prepared in the present application can maintain a potential of about -1.0 V vs. RHE at a potential of -100 mA cm -2 , and the HCOOH faradic efficiency decreases around 50 h, but is still maintained at more than 80%.

[0062] The above experimental results show that the Bi2O3@PCN-222 material prepared in the application can regulate the load of Bi element, and then realize high HCOOH selectivity in the process of electrocatalytic carbon dioxide reduction reaction. The application specifically uses a structure and coordination clear metal-organic framework material (MOF: PCN-222) as a carrier, constructs a Bi2O3@PCN-222 catalyst through a host-guest synthesis strategy, and realizes high activity and high stability electrocatalytic CO2 reduction. The feature is that by regulating the addition of different amounts of bismuth nitrate, catalysts with different bismuth contents can be prepared. The Bi2O3@PCN-222 material prepared by the method is used in the electrocatalytic carbon dioxide reduction reaction, and HCOOH selectivity is realized. This work will expand the application field of MOF-based electrocatalysts, and will also provide theoretical guidance for designing efficient CO2 reduction single-atom electrocatalytic materials.

[0063] The above only describes the preferred embodiments and experimental examples of the application, and is not used to limit the protection scope of the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A spindle-shaped Bi2O3@PCN-222 catalyst, characterized in that: The steps include: (1) Dissolve zirconium oxychloride octahydrate and tetrakis(4-carboxyphenyl)porphyrin in a certain stoichiometric ratio in N,N-dimethylformamide, stir well, and then add difluoroacetic acid: (2) adding the uniformly stirred solution in (1) to a high-pressure reactor, placing it in an oven, heating it for a certain period of time, cooling it to room temperature, washing it three times with N,N-dimethylformamide and anhydrous ethanol, centrifuging it, and drying it in a vacuum drying oven to obtain a MOF precursor; (3) dissolving the MOF precursor and soluble bismuth salt obtained in (2) in N,N-dimethylformamide and stirring and dissolving; (4) The uniformly stirred solution in (3) was added to a high-pressure reactor, placed in an oven, heated for a certain period of time, cooled to room temperature, washed three times with N,N-dimethylformamide and anhydrous ethanol, respectively, and centrifuged, and placed in a vacuum drying oven to dry, thereby obtaining Bi2O3@PCN-222.

2. The MOF precursor and preparation method thereof according to claim 1, characterized in that: In step (1), the total amount of zirconium oxychloride octahydrate added to the reaction system is 100-500 mg, preferably 100-300 mg; the total amount of tetrakis(4-carboxyphenyl)porphyrin added is 10-100 mg, preferably 10-60 mg; the total amount dissolved in N,N-dimethylformamide is 20-200 mL, preferably 20-100 mL; and the total amount of difluoroacetic acid added is 1-10 mL, preferably 1-5 mL.

3. The MOF precursor and preparation method thereof according to claim 1, characterized in that: In step (2), the temperature of heating the reaction system in a vacuum drying oven is 100-200° C., preferably 100-150° C.; the heating time is 12-48 h, preferably 16-32 h.

4. The Bi2O3@PCN-222 and preparation method thereof according to claim 1, characterized in that: The soluble bismuth salt is selected from at least any one of bismuth nitrate, bismuth chloride and bismuth sulfate.

5. The Bi2O3@PCN-222 and preparation method thereof according to claim 1, characterized in that: The total amount of MOF precursor added to the reaction system in step (3) is 100-500 mg, preferably 100-300 mg.

6. The Bi2O3@PCN-222 and preparation method thereof according to claim 1, characterized in that: The total amount of bismuth nitrate pentahydrate added to the reaction system in step (3) is 100-500 mg, preferably 100-300 mg.

7. The Bi2O3@PCN-222 and preparation method thereof according to claim 1, characterized in that: The total amount of N,N-dimethylformamide added to the reaction system in step (3) is 20-200 mL, preferably 20-100 mL.

8. The Bi2O3@PCN-222 and preparation method thereof according to claim 1, characterized in that: The stirring time in the reaction system of step (3) is 30-100 min, preferably 30-60 min.

9. The Bi2O3@PCN-222 and preparation method thereof according to claim 1, characterized in that: In step (4), the temperature of heating the reaction system in a vacuum drying oven is 100-200° C., preferably 100-150° C.; the heating time is 12-48 h, preferably 16-32 h.

10. Use of Bi2O3@PCN-222 obtained by the method of any one of claims 1 to 9 in the electroreduction of carbon dioxide, preferably in the production of formic acid from carbon dioxide. The Bi2O3@PCN-222 material obtained by the method described above is subjected to electrocatalytic reduction of carbon dioxide to formic acid in a carbon dioxide-saturated 0.005M H2SO4 and 0.5M K2SO4 solution as the electrolyte.

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