A low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst and a preparation method thereof

Abstract

The application discloses a low-noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst and a preparation method thereof, and belongs to the field of electrocatalytic water splitting catalysts. The catalyst is a Ni and La double-doped non-noble metal Co3O4 carrier loaded with Ir and Pt noble metals, and is a bifunctional catalyst with oxygen evolution and hydrogen evolution catalytic effects. The application provides a design idea of carrier and bifunctional catalyst synergistic catalytic reaction. The carrier has sufficient dispersion and anchoring effects on the noble metals, and can synergistically catalyze the reaction with the noble metals. Therefore, the prepared bifunctional catalyst reduces the noble metal loading, and improves the overall catalytic activity and stability of the catalyst.

Description

TECHNICAL FIELD

[0001] The present application relates to a low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst and a preparation method thereof, and belongs to the field of electrocatalytic water splitting for hydrogen production. BACKGROUND

[0002] Proton exchange membrane water electrolysis technology is the most rapidly developed water splitting technology in recent years, and the anode oxygen evolution reaction catalyst and the cathode hydrogen evolution reaction catalyst are the key to the application of PEMWE technology. Developing a bifunctional oxygen evolution / hydrogen evolution catalyst is the key to promoting the industrial application of PEMWE. Existing researches mainly focus on single-function catalysts, and Ir-based noble metal catalysts are typical oxygen evolution reaction catalysts, and Pt-based catalysts are typical hydrogen evolution reaction catalysts.

[0003] Although single-function catalysts have been widely researched and developed, the research and development of bifunctional catalysts are not deep. Chinese patent 202210996048.7 discloses "a Fe-doped Co3O4 supported Ru bifunctional catalyst for electrocatalytic water splitting and a preparation method thereof", which first synthesizes Fe-doped Co3O4 nano-mesoporous material as a carrier by a template method, then loads ruthenium salt on the Fe-doped Co3O4 carrier by impregnation, and obtains a Ru / Fe-Co3O4 catalyst after heat treatment, i.e. the Fe-doped Co3O4 supported Ru bifunctional electrocatalyst.

[0004] However, whether it is a single-function catalyst or a bifunctional catalyst, the noble metal loading is high, which leads to extremely high catalyst cost and limits the widespread development of water splitting for hydrogen production. Moreover, the working environment of water splitting for hydrogen production catalysts is a strong oxidizing or strong acidic environment, and the stability of existing catalysts cannot meet the requirements of industrial applications.

[0005] PURPOSE OF THE INVENTION

[0006] Based on the above problems, the first aspect of the present application is to provide an oxygen evolution and hydrogen evolution bifunctional catalyst with low noble metal dosage and good catalytic activity.

[0007] The technical solutions adopted by the present application are as follows:

[0008] A low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst, which uses Ni and La double-doped non-noble metal Co3O4 as a carrier and loads Ir and Pt noble metals, and is a bifunctional catalyst with oxygen evolution and hydrogen evolution catalytic effects.

[0009] The low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst of the present application has a small particle size and a porous structure, and the noble metals are uniformly distributed on the surface and in the pores of the carrier.

[0010] The low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst of the application has a noble metal content less than 7% as tested by ICP, and more specifically, the total content of Ir and Pt in the catalyst is 6.7%.

[0011] The low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst of the application reduces the use of noble metals and the cost while improving the overall activity of the catalyst.

[0012] The second aspect of the application is to provide a preparation method of a low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst, comprising the following steps:

[0013] (1) Preparation of the carrier:

[0014] Cobalt nitrate, lanthanum nitrate and nickel nitrate are added to a solvent to form A liquid; 2-methylimidazole is added to a solvent to form B liquid; A liquid is poured into B liquid, and the mixture is left to stand, centrifuged and washed to obtain a precipitate; the precipitate is ball milled and calcined to obtain the carrier LN-MOF-C;

[0015] (2) Preparation of the bifunctional catalyst:

[0016] Ir, Pt, p-benzenedicarboxaldehyde or glyoxal and citric acid are added to benzyl alcohol to form a mixed solution; the LN-MOF-C prepared in step (1) is added to the mixed solution, and a uniform suspension is obtained after ultrasonic and stirring; the suspension is heated while stirring, and after cooling, the suspension is centrifuged to obtain a precipitate which is washed and dried, and then sintered to obtain the bifunctional catalyst.

[0017] As a preferred embodiment:

[0018] In step (1):

[0019] The solvent is methanol.

[0020] The ball milling has a rotation speed of 200-600 rpm and a duration of 10-240 min.

[0021] The calcination is performed at 400-650℃ under argon atmosphere for 0.5-6h.

[0022] In step (2):

[0023] The suspension is heated while stirring, and the heating temperature is 150-220℃, and the holding time is 1-12h.

[0024] The drying is vacuum drying or freeze drying, and the drying time is 12-72h.

[0025] The sintering is performed at 300-480℃ under air atmosphere for 1-8h.

[0026] Particularly preferably, the present application provides a method for preparing a low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst, comprising the following steps:

[0027] (1) Preparation of the carrier:

[0028] 2-10 g of cobalt nitrate, 0.5-6 g of lanthanum nitrate, and 0.5-3 g of nickel nitrate are added to methanol to completely dissolve and form A liquid; 2-20 g of 2-methylimidazole is added to methanol to completely dissolve and form B liquid; A liquid is poured into B liquid while stirring B liquid, and after waiting for AB liquid to be fully mixed, it is left to stand for 1-48 h; the mixed liquid after sufficient standing is centrifuged, and the precipitate is washed with methanol or ethanol; the precipitate is ball milled, the ball milling speed is 200-600 rpm, and the ball milling time is 10-240 min; the powder after ball milling is calcined at 400-650℃ under argon atmosphere for 0.5-6 h to obtain the carrier LN-MOF-C;

[0029] (2) Preparation of the bifunctional catalyst:

[0030] 20-60 mg of Ir, 20-60 mg of Pt, 1-6 g of p-phenylenediformaldehyde or glyoxal, and 0.5-6 g of citric acid are added to 40-90 ml of benzyl alcohol, and after being fully ultrasonically treated and stirred, a uniform mixed solution is formed; 100 mg of LN-MOF-C prepared in step (1) is added to the mixed solution, and after ultrasonic treatment and stirring, a uniform suspension is obtained; the suspension is heated to 150-220℃ while stirring, and after being kept at this temperature for 1-12 h, the suspension is centrifuged to obtain a precipitate which is washed with ethanol or acetone; the precipitate is vacuum dried or freeze-dried for 12-72 h, and after drying, it is sintered in air atmosphere at 300-480℃ for 1-8 h to obtain the bifunctional catalyst.

[0031] A third aspect of the present application is to provide an application of the low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst in water electrolysis catalytic reaction, including water electrolysis catalytic oxygen evolution reaction and hydrogen evolution reaction.

[0032] Specifically, the present application provides an application of the low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst in hydrogen production by electrocatalytic water splitting in an acidic environment, in which the bifunctional catalyst material is used as the cathode and anode of the proton membrane electrode, and then used in the proton membrane electrolytic cell for electrocatalytic water splitting to produce hydrogen.

[0033] The beneficial effects of the present application are as follows:

[0034] (1) The application provides a design idea of synergistically catalyzing a reaction by a carrier and a bifunctional catalyst, taking non-noble metal Co3O4 as a substrate, reducing Ir and Pt on the surface of the substrate at the same time, the carrier having sufficient dispersion and anchoring effect on the noble metals, and the carrier being capable of synergistically catalyzing a reaction with the noble metals. Therefore, the prepared bifunctional catalyst reduces the loading of noble metals, and improves the overall catalytic activity and stability of the catalyst.

[0035] (2) The application provides a preparation method of a low-noble-metal-loading oxygen evolution and hydrogen evolution bifunctional catalyst.

[0036] The application will be further described below in combination with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The XRD pattern of the bifunctional catalyst prepared in the embodiment of the application.

[0038] Figure 2 The anode oxygen evolution reaction stability test data of the bifunctional catalyst prepared in the embodiment of the application at 10 mA / cm2.

[0039] Figure 3 The cathode hydrogen evolution reaction stability test data of the bifunctional catalyst prepared in the embodiment of the application at -10 mA / cm2. DETAILED DESCRIPTION

[0040] In the following embodiments, existing or commercially available products are used, except for specifically stated otherwise.

[0041] Embodiment 1

[0042] (1) Preparation and sintering of the carrier:

[0043] A solution was prepared by dissolving 6 g of cobalt nitrate, 2 g of lanthanum nitrate, and 1 g of nickel nitrate in 150 ml of methanol. A second solution was prepared by dissolving 14 g of 2-methylimidazole in 400 ml of methanol. The first solution was added to the second solution while stirring. After the solutions were mixed, the mixture was allowed to stand for 12 hours. The precipitate was obtained by centrifugation and washing with methanol or ethanol. The precipitate was ball-milled at a speed of 600 rpm for 60 minutes. The ball-milled powder was calcined at 550°C for 4 hours under an argon atmosphere to obtain a support LN-MOF-C.

[0044] (2) Preparation of a bifunctional catalyst by loading a noble metal on the support:

[0045] A solution was prepared by dissolving 40 mg of Ir, 40 mg of Pt, 3 g of terephthaldehyde or glyoxal, and 1.5 g of citric acid in 70 ml of benzyl alcohol. The solution was ultrasonically stirred to obtain a uniform mixture. 100 mg of the support LN-MOF-C was added to the mixture and ultrasonically stirred to obtain a uniform suspension. The suspension was heated to 200°C while stirring for 6 hours. After the suspension was cooled, the precipitate was obtained by centrifugation and washing with ethanol or acetone. The precipitate was vacuum dried or freeze-dried for 48 hours. After drying, the bifunctional catalyst was obtained by sintering at 400°C for 4 hours under an air atmosphere.

[0046] Confirmation of the structure of the catalyst:

[0047] Reference Figure 1 The TEM image of the bifunctional catalyst of the present application shows that the support has a small particle size and a porous structure, and the noble metal is uniformly distributed on the surface and in the pores of the support. The ICP test results show that the content of Ir and Pt in the bifunctional catalyst is 6.7%.

[0048] Performance test:

[0049] The intrinsic electrochemical activity of the material was tested in a typical three-electrode system using a rotating disc electrode as the working electrode, a gold electrode as the counter electrode, a mercury / mercurous sulfate electrode as the reference electrode, and 0.1 M HCIO4 as the electrolyte. The intrinsic electrochemical stability of the system was tested under the same system at a current density of 10 mA / cm2.

[0050] Analysis:

[0051] As shown in Figure 2 , the anodic oxygen evolution reaction stability test data of the bifunctional catalyst at 10 mA / cm2showed that the anodic oxygen evolution reaction stability at 10 mA / cm2exceeded 20 hours, proving that the bifunctional catalyst prepared by the present application has good oxygen evolution reaction stability. As shown in Figure 2It can be read that the potential of the bifunctional catalyst at 10 mA / cm2 is 1.6 V (RHE, uncorrected), and the corresponding 10 mA / cm2 overpotential is 370 mV (uncorrected), proving that the catalyst has excellent oxygen evolution activity.

[0052] Figure 3 The cathode hydrogen evolution reaction stability test data of the bifunctional catalyst at -10 mA / cm2 is shown, and the hydrogen evolution reaction stability at -10 mA / cm2 is more than 16 h, proving that the bifunctional catalyst prepared by the application has good hydrogen evolution reaction activity and stability. Figure 3 It can be read that the potential of the bifunctional catalyst at -10 mA / cm2 is -0.081 V (RHE, uncorrected), and the corresponding -10 mA / cm2 overpotential is 81 mV (uncorrected), proving that the catalyst has excellent hydrogen evolution activity.

[0053] In summary, the bifunctional catalyst prepared by the application has a large specific surface area of the carrier, which can be fully dispersed in the noble metal, the noble metal has a small particle size and a large specific surface area, and the carrier and the noble metal have a synergistic catalytic effect, so it can be used for water splitting to produce hydrogen in an acidic environment, and has excellent oxygen evolution reaction and hydrogen evolution reaction performance.

[0054] Example 2

[0055] The preparation method is the same as that in Example 1, except that in step (2), the precipitant is dried and then sintered in an air atmosphere at 360 degrees Celsius for 2 hours to obtain the bifunctional catalyst.

[0056] Example 3

[0057] The preparation method is the same as that in Example 1, except that in step (2), the precipitant is dried and then sintered in an air atmosphere at 360 degrees Celsius for 4 hours to obtain the bifunctional catalyst.

[0058] Example 4

[0059] The preparation method is the same as that in Example 1, except that in step (2), the precipitant is dried and then sintered in an air atmosphere at 400 degrees Celsius for 2 hours to obtain the bifunctional catalyst.

[0060] Performance test:

[0061] The bifunctional catalysts prepared in Examples 2-4 are tested for their catalytic performance using the aforementioned method to evaluate the influence of different preparation processes on the performance of the catalysts, as shown in Table 1:

[0062]

Claims

1. A low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst, characterized in that: The catalyst is a non-noble metal Co3O4 doped with Ni and La as a carrier, and loaded with Ir and Pt noble metals, and is a bifunctional catalyst with oxygen evolution and hydrogen evolution catalytic effects. The preparation method of the bifunctional catalyst comprises the following steps: (1) Preparation of the carrier: Dissolve cobalt nitrate, lanthanum nitrate and nickel nitrate in a solvent to form A liquid; dissolve 2-methylimidazole in a solvent to form B liquid; pour A liquid into B liquid, stand, centrifuge and wash to obtain a precipitate; ball mill and calcine the precipitate to obtain the carrier LN-MOF-C; (2) Preparation of the bifunctional catalyst: Add Ir, Pt, p-benzaldehyde or glyoxal and citric acid into benzyl alcohol to form a mixed solution; add the LN-MOF-C prepared in step (1) into the mixed solution, and obtain a uniform suspension after ultrasonic and stirring; centrifuge the suspension after heating to obtain a precipitate, and wash and dry the precipitate, and then sinter to obtain the bifunctional catalyst.

2. The low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst according to claim 1, characterized in that: The carrier of the bifunctional catalyst is a small-particle-size porous structure, and the noble metals are uniformly distributed on the surface and in the pore structure of the carrier.

3. The low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst of claim 1, wherein: The content of noble metals in the catalyst is less than 7% according to ICP test.

4. A method for preparing the low noble metal loading bi-functional catalyst for oxygen evolution and hydrogen evolution according to any one of claims 1 to 3, characterized in that, Comprise the following steps: (1) Preparation of the carrier: Dissolve cobalt nitrate, lanthanum nitrate and nickel nitrate in a solvent to form A liquid; dissolve 2-methylimidazole in a solvent to form B liquid; pour A liquid into B liquid, stand, centrifuge and wash to obtain a precipitate; ball mill and calcine the precipitate to obtain the carrier LN-MOF-C; (2) Preparation of the bifunctional catalyst: Add Ir, Pt, p-benzaldehyde or glyoxal and citric acid into benzyl alcohol to form a mixed solution; add the LN-MOF-C prepared in step (1) into the mixed solution, and obtain a uniform suspension after ultrasonic and stirring; centrifuge the suspension after heating to obtain a precipitate, and wash and dry the precipitate, and then sinter to obtain the bifunctional catalyst.

5. The method for preparing a low noble metal loading oxygen and hydrogen evolution bifunctional catalyst according to claim 4, wherein: In step (1), the solvent is methanol, the ball milling speed is 200-600 rpm, the ball milling time is 10-240 min, and the calcination is performed at 400-650 DEG C under argon atmosphere for 0.5-6 h.

6. The method for preparing a low noble metal loading bifunctional catalyst for oxygen and hydrogen evolution according to claim 4, wherein: In step (2), the suspension is heated while stirring, the heating temperature is 150-220 DEG C, the holding time is 1-12 h, the drying is vacuum drying or freeze drying, the drying time is 12-72 h, and the sintering is performed at 300-480 DEG C in air atmosphere for 1-8 h.

7. The method for preparing a low-noble metal-loaded bifunctional catalyst for oxygen and hydrogen evolution according to claim 4, wherein: Comprise the following steps: (1) Preparation of the carrier: 2-10 g of cobalt nitrate, 0.5-6 g of lanthanum nitrate, 0.5-3 g of nickel nitrate were added into methanol to form a complete solution to form A liquid; 2-20 g of 2-methylimidazole was added into methanol to form a complete solution to form B liquid; A liquid was poured into B liquid while stirring B liquid, and after waiting for AB liquid to be fully mixed, it was left to stand for 1-48 h; the mixed liquid after sufficient standing was centrifuged, and the precipitate was washed with methanol or ethanol; the precipitate was ball milled, the ball milling speed was 200-600 rpm, and the ball milling time was 10-240 min; the ball milled powder was calcined at 400-650℃ under argon atmosphere for 0.5-6 h to obtain the carrier LN-MOF-C; (2) Preparation of a bifunctional catalyst: 20-60 mg of Ir, 20-60 mg of Pt, 1-6 g of p-phenylenediformaldehyde or glyoxal and 0.5-6 g of citric acid were added into 40-90 ml of benzyl alcohol, and after being fully ultrasonicated and stirred, a uniform mixed solution was formed. 100 mg of LN-MOF-C prepared in step (1) was added into the mixed solution, and after being ultrasonicated and stirred, a uniform suspension was obtained. The suspension was heated to 150-220℃ while stirring, and after being kept for 1-12 h, the suspension was centrifuged to obtain a precipitate which was washed with ethanol or acetone. The precipitate was vacuum dried or freeze-dried for 12-72 h, and after drying, it was sintered in air atmosphere at 300-480℃ for 1-8 h to obtain a bifunctional catalyst.

8. Application of the low noble metal loading bifunctional catalyst for oxygen evolution and hydrogen evolution in the catalytic reaction of electrolysis of water, including catalytic oxygen evolution reaction and hydrogen evolution reaction of electrolysis of water.

9. Use of the low noble metal loading oxygen evolution and hydrogen evolution bifunctional catalyst according to any one of claims 1 to 3 in the catalysis of water electrolysis, characterized in that: The low noble metal loading bifunctional catalyst for oxygen evolution and hydrogen evolution is used for electrocatalytic water splitting to produce hydrogen in an acidic environment. The bifunctional catalyst material is used as the cathode and anode of the proton membrane electrode, respectively, and then used in the proton membrane electrolytic cell for electrocatalytic water splitting to produce hydrogen.

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