Sr-based bifunctional perovskite electrocatalytic material, and preparation method and application thereof

Abstract

The application belongs to the technical field of electrocatalytic materials, and particularly relates to a Sr-based bifunctional perovskite electrocatalytic material and a preparation method and application thereof. The electrocatalytic material is a Sr-based perovskite oxide, and the micro-morphology of the electrocatalytic material is nanoparticles, and the particle size of the nanoparticles is 10-90 nm. The electrocatalytic material has good OER and HER catalytic activity, can be used in fuel cells and water electrolysis and the like, and has good catalytic activity. The Sr-based bifunctional perovskite electrocatalytic material prepared by the application has a nanoparticle structure and small particle size, increases the active area of the catalyst, thereby improving the electrocatalytic activity, and has a good application prospect in the field of water electrolysis. The preparation method is simple and safe and environmentally friendly, and has good economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology, and particularly relates to an Sr-based bifunctional perovskite electrocatalytic material, its preparation method and application. Background Technology

[0002] Developing sustainable and clean energy sources and reducing dependence on fossil fuels is one of the major challenges facing humanity today. Hydrogen energy, as a clean energy source with high calorific value and zero pollution, is considered one of the most promising energy sources. Electrochemical water splitting for hydrogen production produces no pollutants and is an important hydrogen production pathway. However, both the oxygen evolution reaction (OER) at the cathode and the hydrogen evolution reaction (HER) at the anode are slow-kind processes in water electrolysis, resulting in high overpotentials. This leads to high decomposition voltages, low electrolysis efficiency, and high energy consumption. To address these issues, highly efficient electrocatalysts are typically needed to reduce the overpotentials of OER and HER. Currently, highly efficient electrocatalysts used for OER and HER are mainly noble metal-based catalysts such as RuO2, IrO2, and Pt. However, the use of noble metals significantly increases the cost of water electrolysis equipment. Therefore, developing non-noble metal electrocatalysts with lower overpotentials is of great significance for reducing the cost of water electrolysis, improving water splitting efficiency, and reducing energy consumption.

[0003] In recent years, perovskite oxides have been widely studied due to their unique crystal structure and excellent electrocatalytic activity in OER and HER. For example, a method for preparing layered iridium-based perovskites using a high-temperature solid-state reaction is disclosed in the prior art. The steps are as follows: a certain amount of SrCO3 and Ir powder are thoroughly ground and mixed uniformly in malleable iron slurry; the resulting mixture is calcined at 900–1000℃ for 8–12 h, then heated to 1100–1200℃ for 8–12 h, and finally cooled to room temperature to obtain layered iridium-based perovskites. However, the iridium-based perovskites obtained by this method suffer from problems such as large and uneven particle size, poor electrocatalytic activity, and poor stability, thus limiting their application and development.

[0004] Therefore, it is urgent to develop small-sized and high-performance perovskite oxides as catalysts for water electrolysis. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a Sr-based bifunctional perovskite electrocatalytic material. The Sr-based perovskite electrocatalytic material of this invention has excellent OER and HER electrocatalytic activity, is a bifunctional electrocatalyst, and has good stability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A Sr-based bifunctional perovskite electrocatalytic material, wherein the material is an Sr-based perovskite oxide; its microstructure is nanoparticles with a particle size of 10–90 nm.

[0008] This invention also provides a method for preparing perovskite-type electrocatalytic materials. The invention uses PVP as a complex and employs a sol-gel method to prepare bifunctional electrocatalytic materials. Compared to traditional sol-gel methods, solid-phase synthesis methods, and novel chemical synthesis methods, this method significantly reduces the catalyst synthesis temperature and time. Furthermore, the preparation method is simple, the conditions are easy to achieve, and it can be mass-produced, showing promising application prospects.

[0009] The preparation method is as follows: the traditional sol-gel method is improved by using PVP as a complex to prepare perovskite electrocatalytic materials with nanoscale bifunctionality.

[0010] The preparation method of the above-mentioned bifunctional perovskite electrocatalytic material specifically includes the following steps:

[0011] (1) To prepare the sol gel, different elemental compounds were mixed with polyvinylpyrrolidone (PVP) at room temperature, and then added to deionized water, N,N-dimethylformamide (DMF) and anhydrous ethanol. The mixture was stirred and mixed evenly, and finally dried under vacuum to obtain the sol gel.

[0012] (2) The sol-gel in step (1) is sintered to obtain the nano bifunctional perovskite electrocatalytic material.

[0013] According to the present invention, preferably, the different elemental compounds mentioned in step (1) are strontium nitrate, cobalt nitrate, ferric nitrate, and ammonium molybdate.

[0014] According to the present invention, preferably, the molar ratios of the three different components—strontium nitrate, cobalt nitrate, ferric nitrate, and ammonium molybdate—in step (1) are 10:5:4:1, 10:5:4.5:0.5, and 10:5:5:0. The corresponding masses of polyvinylpyrrolidone (PVP) are 2.0 g, 1.9 g, and 1.8 g, respectively.

[0015] According to the present invention, preferably, the deionized water, N,N-dimethylformamide (DMF) and anhydrous ethanol in step (1) are selected in three different volume ratios, namely 2:1:7, 2:1:5 and 2:1:8.

[0016] According to the present invention, preferably, the stirring time in step (1) is 8-10 h and the stirring speed is 600 rpm / min.

[0017] According to the present invention, preferably, the drying temperature in step (1) is 80-100 °C and the drying time is 12-14 h.

[0018] According to the present invention, preferably, the sintering in step (2) is a two-step sintering; the first step sintering temperature is 200-350 ℃ and the time is 1-2 h; the second step sintering temperature is 750-900 ℃ and the time is 6-8 h.

[0019] The above-mentioned perovskite electrocatalytic materials can be used as electrocatalysts for fuel cells and water electrolysis technologies, and have good OER and HER catalytic activity.

[0020] Beneficial effects

[0021] This invention discloses an Sr-based bifunctional perovskite electrocatalytic material and its preparation method. Compared with the prior art, the beneficial effects of this invention are as follows:

[0022] This invention discloses a Sr-based bifunctional perovskite electrocatalyst material comprising the following metal elements: Sr, Co, Mo, and Fe. The Sr-based bifunctional perovskite electrocatalyst provided by this invention improves catalytic activity and stability by adjusting the types and ratios of alkaline earth metals and transition metals. The electrocatalyst provided by this invention exhibits good OER and HER catalytic activity and can be used in technologies such as fuel cells and water electrolysis with excellent catalytic activity.

[0023] This invention also provides a method for preparing Sr-based bifunctional perovskite electrocatalysts. This method improves upon the traditional sol-gel method by using PVP as a complex to prepare bifunctional perovskite electrocatalysts with tiny nanoparticles, reducing catalyst preparation costs and reaction conditions. This method is simple and effective for preparing Sr-based bifunctional perovskite electrocatalysts. The prepared Sr-based bifunctional perovskite electrocatalysts have a nanoparticle structure and small particle size, increasing the active surface area of ​​the catalyst and thus improving electrocatalytic activity. It shows promising application prospects in the field of water electrolysis. The preparation method provided by this invention is simple to operate, safe, environmentally friendly, and has good economic benefits. Attached image description:

[0024] Figure 1 The X-ray diffraction patterns of the Sr-based bifunctional perovskite electrocatalysts prepared in Examples 1, 2, and 3 of this invention are shown below.

[0025] Figure 2 This is a scanning electron microscope image of the Sr-based bifunctional perovskite electrocatalyst material prepared in Example 1 of the present invention;

[0026] Figure 3 Transmission electron microscope (TEM) images of the Sr-based bifunctional perovskite electrocatalyst materials prepared in Examples 1, 2, and 3 of this invention;

[0027] Figure 4The OER polarization curves of the Sr-based bifunctional perovskite electrocatalyst materials prepared in Examples 1, 2, and 3 of this invention are shown in O2-saturated 1M KOH solution at a scan rate of 10 mV / s.

[0028] Figure 5 The image shows the HER polarization curves of the Sr-based bifunctional perovskite electrocatalysts prepared in Examples 1, 2, and 3 of this invention in an O2-saturated 1M KOH solution at a scan rate of 10 mV / s. Detailed Implementation

[0029] The present invention will now be described in detail. Before proceeding with the description, it should be understood that the terminology used in this specification and the appended claims should not be construed as limited to its general or dictionary meaning, but rather should be interpreted according to the meaning and concept corresponding to the technical aspects of the invention, based on the principle that the inventors are allowed to appropriately define the terms for the best interpretation. Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention. It should be understood that other equivalents or modifications can be obtained from it without departing from the spirit and scope of the invention.

[0030] The following embodiments are merely examples illustrating implementations of the present invention and do not constitute any limitation on the present invention. Those skilled in the art will understand that modifications made without departing from the spirit and concept of the present invention fall within the protection scope of the present invention. Unless otherwise specified, the reagents and instruments used in the following embodiments are commercially available products.

[0031] Terminology Explanation:

[0032] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0033] Example 1

[0034] This embodiment provides a Sr-based bifunctional perovskite electrocatalyst material SrCo. 0.5 Fe 0.4 Mo 0.1 O3 is prepared by the following method:

[0035] (1) Weigh 10 mmol of strontium nitrate, 5 mmol of cobalt nitrate, 4 mmol of ferric nitrate, 1 mmol of ammonium molybdate, and 2.0 g of polyvinylpyrrolidone (PVP) and dissolve them in a mixed solution of 8 mL of deionized water, 4 mL of N,N-dimethylformamide (DMF), and 28 mL of anhydrous ethanol. Stir magnetically at room temperature at 600 rpm / min for 9 h to obtain a uniformly mixed sol solution.

[0036] (2) The product obtained in step (1) was transferred to a vacuum drying oven and dried at 90°C for 12 h to obtain a brownish-red gel-like precursor.

[0037] (3) The brownish-red gel-like precursor obtained in step (2) is placed in a tube furnace for the first step of sintering. The temperature is set to rise from room temperature to 300°C at a rate of 5°C / min. Then, it is calcined at 300°C for 1 h. After cooling, it is ground to obtain a black powder sample.

[0038] (4) The black powder sample obtained in step (3) is placed in a tube furnace for the second sintering step. The temperature is set to rise from room temperature to 800℃ at a rate of 5℃ / min. Then, it is calcined at 800℃ for 7 h. After cooling, it is ground to obtain the final sample.

[0039] Upon testing, the phase structure of the sample in this embodiment is as follows: Figure 1 As shown, from Figure 1 It can be seen from the data that the material is a perovskite oxide.

[0040] The perovskite electrocatalyst material SrCo prepared in this embodiment 0.5 Fe 0.4 Mo 0.1 The scanning electron microscopy (SEM) results of O3 are as follows: Figure 2 As shown. From Figure 2 It can be seen that the prepared sample has a nanoparticle structure with a particle size of 10-90 nm.

[0041] The perovskite electrocatalyst material SrCo prepared in this embodiment 0.5 Fe 0.4 Mo 0.1 The electrocatalytic performance of O3 is as follows: Figure 4 , 5 As shown, from Figure 4 , 5 As can be seen from this example, the perovskite electrocatalyst material SrCo prepared in this instance... 0.5 Fe 0.4 Mo 0.1 O3 exhibits excellent OER and HER properties.

[0042] Example 2

[0043] This embodiment provides a Sr-based bifunctional perovskite electrocatalyst material SrCo. 0.5 Fe 0.45 Mo 0.05 O3 is prepared by the following method:

[0044] (1) Weigh 10 mmol of strontium nitrate, 5 mmol of cobalt nitrate, 4.5 mmol of ferric nitrate, 0.5 mmol of ammonium molybdate, and 1.9 g of polyvinylpyrrolidone (PVP) and dissolve them in a mixed solution of 8 mL of deionized water, 4 mL of N,N-dimethylformamide (DMF), and 20 mL of anhydrous ethanol. Stir magnetically at room temperature at 600 rpm / min for 8 h to obtain a uniformly mixed sol solution.

[0045] (2) The product obtained in step (1) was transferred to a vacuum drying oven and dried at 80°C for 12 h to obtain a brownish-red gel-like precursor.

[0046] (3) The brownish-red gel-like precursor obtained in step (2) was placed in a tube furnace for the first step of sintering. The temperature was programmed to rise from room temperature to 350°C at a rate of 5°C / min. Then, it was calcined at 350°C for 1.5 h. After cooling, it was ground to obtain a black powder sample.

[0047] (4) The black powder sample obtained in step (3) is placed in a tube furnace for the second sintering step. The temperature is set to rise from room temperature to 750°C at a rate of 5°C / min. Then, it is calcined at 750°C for 6 hours. After cooling, it is ground to obtain the final sample.

[0048] Upon testing, the phase structure of the sample in this embodiment is as follows: Figure 1 As shown, from Figure 1 It can be seen from the data that the material is a perovskite oxide.

[0049] The perovskite electrocatalyst material SrCo prepared in this embodiment 0.5 Fe 0.45 Mo 0.05 Transmission electron microscopy (TEM) results of O3 are as follows: Figure 3 As shown. From Figure 3 It can be seen that the prepared sample has a nanoparticle structure with a particle size of 10-90 nm.

[0050] The perovskite electrocatalyst material SrCo prepared in this embodiment 0.5 Fe 0.45 Mo 0.05 The electrocatalytic performance of O3 is as follows: Figure 4 , 5 As shown, from Figure 4 , 5 As can be seen from this example, the perovskite electrocatalyst material SrCo prepared in this instance... 0.5 Fe 0.45 Mo 0.05 O3 exhibits excellent OER and HER properties.

[0051] Example 3

[0052] This embodiment provides a Sr-based bifunctional perovskite electrocatalyst material SrCo. 0.5 Fe 0.5 O3 is prepared by the following method:

[0053] (1) Weigh 10 mmol of strontium nitrate, 5 mmol of cobalt nitrate, 5 mmol of ferric nitrate and 1.8 g of polyvinylpyrrolidone (PVP) and dissolve them in a mixed solution of 8 mL of deionized water, 4 mL of N,N-dimethylformamide (DMF) and 32 mL of anhydrous ethanol. Stir magnetically at room temperature at 600 rpm / min for 10 h to obtain a uniformly mixed sol solution.

[0054] (2) The product obtained in step (1) was transferred to a vacuum drying oven and dried at 100°C for 14 h to obtain a brownish-red gel-like precursor.

[0055] (3) The brownish-red gel-like precursor obtained in step (2) is placed in a tube furnace for the first step of sintering. The temperature is set to rise from room temperature to 200°C at a rate of 5°C / min. Then, it is calcined at 200°C for 2 h. After cooling, it is ground to obtain a black powder sample.

[0056] (4) The black powder sample obtained in step (3) is placed in a tube furnace for the second sintering step. The temperature is set to rise from room temperature to 900℃ at a rate of 5℃ / min. Then, it is calcined at 900℃ for 8 hours. After cooling, it is ground to obtain the final sample.

[0057] Upon testing, the phase structure of the sample in this embodiment is as follows: Figure 1 As shown in the figure, the material is a perovskite oxide.

[0058] The perovskite electrocatalyst material SrCo prepared in this embodiment 0.5 Fe 0.5 The transmission electron microscopy (TEM) results of O3 are as follows: Figure 3 As shown. From Figure 3 It can be seen that the prepared sample has a nanoparticle structure with a particle size of 10-90 nm.

[0059] The perovskite electrocatalyst material SrCo prepared in this embodiment 0.5 Fe 0.5 The electrocatalytic performance of O3 is as follows: Figure 4 , 5 As shown, from Figure 4 , 5 As can be seen from this example, the perovskite electrocatalyst material SrCo prepared in this instance... 0.5 Fe 0.5O3 has relatively good OER and HER properties.

[0060] Application Example 1

[0061] The OER performance testing method is as follows: a three-electrode system is used, with a glassy carbon electrode coated on the sample as the working electrode, a platinum wire as the counter electrode, and a Hg / HgO electrode as the reference electrode. The electrolyte used is a 1 M KOH solution. Oxygen is introduced before the test to saturate the electrolyte with oxygen. The scan rate is 10 mV / s.

[0062] Figure 4 The OER polarization curves of the Sr-based bifunctional perovskite electrocatalysts prepared in Examples 1, 2, and 3 in O2-saturated 1 M KOH solution at a scan rate of 10 mV / s are shown.

[0063] Depend on Figure 4 It can be seen that the Sr-based bifunctional perovskite electrocatalytic material prepared in Example 1 has better OER catalytic performance than the Sr-based bifunctional perovskite electrocatalytic materials prepared in Examples 2 and 3.

[0064] Application Example 2

[0065] The performance testing method for HER is as follows: a three-electrode system is used, with a glassy carbon electrode coated on the sample as the working electrode, a graphite rod as the counter electrode, and an Hg / HgO electrode as the reference electrode. The electrolyte used is a 1 M KOH solution. Nitrogen gas is introduced before the test to saturate the electrolyte with nitrogen. The scan rate is 10 mV / s.

[0066] Figure 5 The image shows the HER polarization curves of the Sr-based bifunctional perovskite electrocatalysts prepared in Examples 1, 2, and 3 in a N2-saturated 1 M KOH solution at a scan rate of 10 mV / s.

[0067] Depend on Figure 5 It can be seen that the Sr-based bifunctional perovskite electrocatalyst material prepared in Example 1 has better HER reaction performance than the Sr-based bifunctional perovskite electrocatalyst materials prepared in Examples 2 and 3.

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A Sr-based bifunctional perovskite electrocatalytic material, characterized in that, The material is an Sr-based perovskite oxide with a microstructure of nanoparticles having a particle size of 10–90 nm; the material is SrCo. 0.5 Fe 0.4 Mo 0.1 O3, SrCo 0.5 Fe 0.45 Mo 0.05 O3; The material exhibits good OER and HER catalytic activity; The preparation method of the Sr-based bifunctional perovskite electrocatalytic material includes the following steps: (1) preparing sol-gel: at room temperature, different elemental compounds are mixed with polyvinylpyrrolidone, and then added to deionized water, N,N-dimethylformamide and anhydrous ethanol and stirred until uniform. Finally, the mixture is dried under vacuum to obtain sol-gel; (2) the sol-gel in step (1) is sintered to obtain the Sr-based bifunctional perovskite electrocatalytic material. The stirring time in step (1) is 8-10 h, and the stirring speed is 600 rpm / min; the drying temperature is 80-100 ℃, and the drying time is 12-14 h. The sintering described in step (2) is a two-step sintering: the first step sintering temperature is 200-350℃ and the time is 1-2h; the second step sintering temperature is 750-900℃ and the time is 6-8h.

2. The Sr-based bifunctional perovskite electrocatalytic material according to claim 1, characterized in that, The different elemental compounds mentioned in step (1) are strontium nitrate, cobalt nitrate, ferric nitrate, and ammonium molybdate.

3. The Sr-based bifunctional perovskite electrocatalyst material according to claim 2, characterized in that, The molar ratios of strontium nitrate, cobalt nitrate, ferric nitrate, and ammonium molybdate in step (1) are 10:5:4:1 and 10:5:4.5:0.5, respectively, corresponding to 2.0 g and 1.9 g of polyvinylpyrrolidone.

4. The Sr-based bifunctional perovskite electrocatalytic material according to claim 1, characterized in that, The volume ratio of deionized water, N,N-dimethylformamide, and anhydrous ethanol mentioned in step (1) is one of 2:1:7 or 2:1:

5.

5. An application of the Sr-based bifunctional perovskite electrocatalytic material as described in claim 1, characterized in that, The electrocatalytic material is used as an electrocatalyst in fuel cells and water electrolysis technologies.

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