Cobalt-based perovskite material and preparation method and application thereof

Abstract

The invention relates to a cobalt-based perovskite material as well as a preparation method and application thereof, relates to the technical field of new materials, and is used for solving at least one of the problems of high pressure, harsh reaction conditions, low yield, high cost and the like of a cobalt-based perovskite material prepared by an existing method. According to the method disclosed by the invention, the physical pressure required by sample preparation is reduced by introducing the chemical pressure through a strategy of coordinated regulation and control of the chemical pressure and the physical pressure; specifically, Ru element is adopted to partially replace Co element, and the cobalt-based perovskite material is synthesized under the condition of lower pressure by introducing a chemical pressure regulation and control mode. According to the method, the synthesis pressure is remarkably reduced, meanwhile, the method has the advantages of being higher in yield, low in cost and the like, the cobalt-based perovskite material is prepared under the mild condition, and a foundation is laid for follow-up electro-catalysis research of the cobalt-based perovskite material.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and in particular to a cobalt-based perovskite material and a preparation method and application thereof. Background Art

[0002] ABO3 type perovskite materials have rich functional properties due to the existence of multiple degrees of freedom such as charge, spin, orbit and lattice. They are a hot topic in the field of materials science and have received widespread attention. 1-x K x BiO3 exhibits superconductivity, La 1-x Sr x MnO3 has giant magnetoresistance, BaTiO3 has ferroelectricity, BiFeO3 has multiferroelectricity, and SrTiO3 has photocatalytic water decomposition. In particular, the new cobalt-based perovskite materials such as CaCoO3 and BiCoO3 prepared in recent years have shown excellent electrocatalytic performance in water splitting, have potential application prospects, and have received extensive research and attention.

[0003] However, in the process of promoting the practical application of CaCoO3 materials, there are still many technical difficulties and challenges. One of the problems is that these materials are difficult to prepare under conventional conditions due to the low matching degree of ion radius and serious crystal structure distortion. They must be prepared by high-pressure and high-temperature synthesis methods with external "physical pressure". At present, the synthesis of CaCoO3 materials still requires a pressure of 8GPa and a temperature of more than 1000℃. The synthesis conditions are very harsh. It must be prepared using a two-stage propulsion high-temperature and high-pressure synthesis device with complex technology, high cost and low efficiency. Limited by the small cavity and low efficiency of the two-stage propulsion high-temperature and high-pressure synthesis device, the large-scale preparation of CaCoO3 materials is restricted, which is not conducive to the electrocatalytic application research of CaCoO3 materials. At present, the size of the CaCoO3 material sample prepared in a single time is only 1-2 mm, and the sample amount is only in the hundreds of milligrams, which seriously restricts the large-scale preparation of materials such as CaCoO3, and is not conducive to the electrocatalytic research and industrial application of cobalt-based perovskite materials.

[0004] Therefore, how to prepare CaCoO3 materials under relatively low pressure or even mild conditions such as normal pressure while ensuring that the performance of the materials is not reduced is a technical difficulty in the field of cobalt-based perovskite electrocatalytic material preparation, and is also of great significance for its application research. For example, once the preparation pressure of the above materials is reduced to less than 5GPa, they can be prepared using a six-sided large cavity high temperature and high pressure synthesis device, and the preparation efficiency and output of the materials can be greatly improved to meet the needs of practical research and application. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a cobalt-based perovskite material and a preparation method and application thereof, so as to solve at least one of the problems of high pressure, harsh reaction conditions, low yield, high cost, etc. of the cobalt-based perovskite material prepared by the existing method.

[0006] In a first aspect, the present invention provides a cobalt-based perovskite material, wherein the molecular formula of the cobalt-based perovskite material is CaCo 1-x Ru x O3, where 0.1≤x≤0.9.

[0007] In a second aspect, the present invention provides a method for preparing a cobalt-based perovskite material, wherein the method comprises the following steps:

[0008] (1) mixing CaO, CoO, RuO2 and an oxidant to obtain an initial mixed powder;

[0009] (2) pressing the initial mixed powder into a sheet to obtain a sheet sample;

[0010] (3) sealing and wrapping the surface of the sheet sample, placing it in a high-pressure synthesis device, and performing a high-temperature and high-pressure synthesis reaction to obtain a product;

[0011] (4) Grinding the product to obtain the cobalt-based perovskite material.

[0012] Furthermore, in step (1), the oxidant includes at least one of KClO4 or NaClO4.

[0013] Furthermore, in step (1), the molar ratio of CaO, CoO, RuO2 and the oxidant is 1:1-x:x:y, wherein 0.1≤x≤0.9 and 0.5≤y≤2.

[0014] Furthermore, in step (2), the thickness of the sheet sample is 1-10 mm.

[0015] Furthermore, in step (3), the sheet sample is sealed and packaged with a gold capsule or a platinum capsule.

[0016] Furthermore, in step (3), the synthesis reaction pressure is 1-5 GPa, the temperature is 800-1200° C., and the reaction time is 0.1-10 h.

[0017] Furthermore, in step (4), after grinding, cleaning and drying are also included.

[0018] Furthermore, the cleaning is cleaning with deionized water.

[0019] Furthermore, the drying temperature is 100-200° C., and the drying time is 1-2 hours.

[0020] Furthermore, in step (4), the molecular formula of the cobalt-based perovskite material is CaCo 1-x Ru x O3, where 0.1≤x≤0.9.

[0021] In a third aspect, the present invention provides an application of the above-mentioned cobalt-based perovskite material in electrochemistry.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] (1) The method of the present invention adopts the strategy of coordinated regulation of "chemical pressure" and "physical pressure" to reduce the physical pressure required for sample preparation by introducing chemical pressure; specifically, Ru element is used to partially replace Co element, and by introducing chemical pressure regulation, cobalt-based perovskite materials are synthesized under relatively low pressure conditions;

[0024] (2) The synthesis pressure is significantly reduced by the method of the present invention, and the method has the advantages of higher yield and lower cost, and realizes the preparation of cobalt-based perovskite materials under relatively mild conditions, laying a foundation for subsequent electrocatalytic research on cobalt-based perovskite materials.

[0025] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0027] Figure 1 This is an X-ray diffraction pattern of the cobalt-based perovskite material prepared in Example 1 of the present invention;

[0028] Figure 2 This is a crystal structure diagram of the cobalt-based perovskite material prepared in Example 1 of the present invention;

[0029] Figure 3 The magnetic susceptibility-temperature curve of the cobalt-based perovskite material prepared in Example 1 of the present invention;

[0030] Figure 4 This is an X-ray diffraction pattern of the cobalt-based perovskite material prepared in Example 2 of the present invention;

[0031] Figure 5This is an X-ray diffraction pattern of the cobalt-based perovskite material prepared in Example 3 of the present invention;

[0032] Figure 6 The X-ray diffraction pattern of the product prepared in Comparative Example 1 of the present invention;

[0033] Figure 7 The X-ray diffraction pattern of the product prepared in Comparative Example 2 of the present invention;

[0034] Figure 8 This is the X-ray diffraction pattern of the product prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0036] A specific embodiment of the present invention discloses a cobalt-based perovskite material, wherein the molecular formula of the cobalt-based perovskite material is CaCo 1-x Ru x O3, wherein 0.1≤x≤0.9, for example, x is 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8.

[0037] Specifically, the cobalt-based perovskite material exhibits antiferromagnetism.

[0038] Another specific embodiment of the present invention discloses a method for preparing a cobalt-based perovskite material, comprising the following steps:

[0039] (1) mixing CaO, CoO, RuO2 and an oxidant to obtain an initial mixed powder;

[0040] (2) pressing the initial mixed powder into a sheet to obtain a sheet sample;

[0041] (3) sealing and wrapping the surface of the sheet sample, placing it in a high-pressure synthesis device, and performing a high-temperature and high-pressure synthesis reaction to obtain a product;

[0042] (4) Grinding the product to obtain the cobalt-based perovskite material.

[0043] Compared with the prior art, the method of the present invention adopts the strategy of coordinated regulation of "chemical pressure" and "physical pressure" to reduce the physical pressure required for sample preparation by introducing chemical pressure; specifically, Ru element is used to partially replace Co element, and by introducing chemical pressure regulation, cobalt-based perovskite material is synthesized under lower pressure conditions;

[0044] The method of the present invention significantly reduces the synthesis pressure and has the advantages of higher yield and low cost. It realizes the preparation of cobalt-based perovskite materials under relatively mild conditions, laying a foundation for subsequent electrocatalytic research on cobalt-based perovskite materials.

[0045] Specifically, in step (1), the molar ratio of CaO, CoO, RuO2 and the oxidant is 1:1-x:x:y, wherein 0.1≤x≤0.9, for example, x is 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.5≤y≤2, for example, y is 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9.

[0046] It should be noted that the present invention uses the oxidant KClO4 or NaClO4 to regulate the oxygen content. Samples with a molar amount y of KClO4 or NaClO4 less than 0.5 cannot be synthesized due to lack of oxygen. Samples with a molar amount y greater than 2 can be synthesized, but there are too many residual KCl or NaCl in the product, which is not conducive to increasing the yield.

[0047] Specifically, in step (1), the oxidant includes at least one of KClO4 or NaClO4.

[0048] Specifically, in step (2), the thickness of the sheet sample is 1-10 mm, for example, the thickness is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, or 9 mm.

[0049] It should be noted that the thickness of the sheet sample is selected within the above range because if it is too low, it will affect the sample yield, and if it is too high, the longitudinal temperature gradient of the sample will be large during synthesis, resulting in uneven synthesized samples.

[0050] Specifically, in step (3), the sheet sample is sealed and packaged with a gold capsule or a platinum capsule.

[0051] It should be noted that the gold capsule or platinum capsule described in the present invention refers to a capsule-shaped hollow structure made of gold or platinum, and the sheet sample is placed in the capsule for sealing. The purpose of sealing and wrapping the sheet sample is to ensure that the oxygen released by the oxidant during the reaction does not overflow and fully participates in the sample synthesis reaction.

[0052] Specifically, in step (3), the pressure of the synthesis reaction is 1-5 GPa, for example, 1 GPa, 1.5 GPa, 2.0 GPa, 2.5 GPa, 3.0 GPa, 3.5 GPa, 4.0 GPa, 4.5 GPa, 5 GPa, the temperature is 800-1200°C, for example, 820°C, 840°C, 860°C, 880°C, 900°C, 920°C, 940°C, 960°C, 980°C, 1000°C, 1020°C, 1040°C, 1060°C, 1080°C, 1100°C, 1120°C, 1140°C, 1160°C, 1180°C, and the reaction time is 0.1-10h, for example, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h.

[0053] It should be noted that the present invention adopts the above synthesis temperature because high or low temperature affects the purity of the product. In addition, if the reaction time is too short, the reaction is not sufficient, which affects the purity of the product. If the reaction time is too long, the product can be prepared, but the synthesis efficiency is affected.

[0054] Specifically, in step (4), after grinding, the process also includes cleaning and drying.

[0055] Specifically, the cleaning is performed with deionized water, and preferably, the cleaning is performed with deionized water 1-3 times.

[0056] It should be noted that the purpose of washing with deionized water is to remove residual KCl or NaCl in the product and improve the purity of the product.

[0057] Specifically, the drying temperature is 100-200°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, and the drying time is 1-2h, for example, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h.

[0058] It should be noted that the above-mentioned drying temperature can ensure that the sample does not decompose and has a higher drying efficiency. If the drying time is too short, the drying is insufficient, residual moisture, and the drying time is too long, the preparation efficiency will be affected.

[0059] Specifically, in step (4), the molecular formula of the cobalt-based perovskite material is CaCo 1-x Ru x O3, where 0.1≤x≤0.9.

[0060] Specifically, in step (4), the high-pressure synthesis device is a six-sided top press.

[0061] The invention adopts a six-sided top press to synthesize the cobalt-based perovskite material into a cylindrical shape with a diameter of 0.5-1 cm, a height of 0.5-1 cm and a weight of 0.5-4 g at one time.

[0062] Another specific embodiment of the present invention discloses an application of the above-mentioned cobalt-based perovskite material in electrochemistry.

[0063] The technical solution of the present invention is further explained below in conjunction with specific embodiments.

[0064] Example 1

[0065] A method for preparing a cobalt-based perovskite material in this embodiment includes the following steps:

[0066] (1) In an inert gas argon atmosphere glove box, CaO, CoO, RuO2 and KClO4 oxidants were mixed uniformly in a molar ratio of 1:0.5:0.5:0.5 to obtain an initial mixed powder;

[0067] (2) pressing the initial mixed powder into a sheet so that the powder particles are fully in contact with each other to obtain a sheet sample, wherein the thickness of the sheet sample is 5 mm;

[0068] (3) placing the sheet sample in a gold capsule, sealing and wrapping it, placing it in the cavity of a six-sided press, and performing a high-temperature and high-pressure synthesis reaction at a pressure of 5 GPa, a temperature of 1100° C., and a reaction time of 0.5 h to obtain a product;

[0069] (4) The product is taken out from the gold capsule, ground into a uniform powder, washed three times with deionized water, and dried at 100° C. for 1 h to obtain the cobalt-based perovskite material.

[0070] The cobalt-based perovskite material prepared in this embodiment is cylindrical, with a diameter of 0.5 cm, a height of 0.5 cm, and a weight of 0.5 g.

[0071] The molecular formula of the cobalt-based perovskite material prepared in this example is CaCo 0.5 Ru 0.5 O3, test the X-ray diffraction of the cobalt-based perovskite material prepared in this embodiment, and the results are as follows Figure 1 shown.

[0072] The crystal structure of the cobalt-based perovskite material prepared in this example is as follows: Figure 2 As shown, it is shown that the material is a perovskite structure material.

[0073] The magnetic properties of the cobalt-based perovskite material prepared in this embodiment were tested using a vibrating sample magnetometer, and the magnetic susceptibility-temperature curve was as follows: Figure 3 As shown, the results show that the sample exhibits antiferromagnetism, T N1=58K,T N2 =41K.

[0074] Example 2

[0075] A method for preparing a cobalt-based perovskite material in this embodiment includes the following steps:

[0076] (1) In an inert gas argon atmosphere glove box, CaO, CoO, RuO2 and KClO4 oxidants were mixed uniformly in a molar ratio of 1:0.8:0.2:1 to obtain an initial mixed powder;

[0077] (2) pressing the initial mixed powder into a sheet so that the powder particles are fully in contact with each other to obtain a sheet sample, wherein the thickness of the sheet sample is 8 mm;

[0078] (3) placing the sheet sample in a platinum capsule, sealing and wrapping it, placing it in the cavity of a six-sided top press, and performing a high temperature and high pressure synthesis reaction at a pressure of 3 GPa, a temperature of 1200° C., and a reaction time of 1 h to obtain a product;

[0079] (4) Taking the product out of the platinum capsule and grinding it into a uniform powder to obtain the cobalt-based perovskite material.

[0080] The cobalt-based perovskite material prepared in this embodiment is cylindrical, with a diameter of 0.8 cm, a height of 0.8 cm, and a weight of 2.2 g. The molecular formula of the cobalt-based perovskite material prepared in this embodiment is CaCo 0.8 Ru 0.2 O3. The X-ray diffraction of the cobalt-based perovskite material prepared in this embodiment is as follows Figure 4 shown.

[0081] The crystal structure and magnetic properties of the cobalt-based perovskite material prepared in this example are basically the same as those in Example 1, and are not listed one by one due to limited space.

[0082] Example 3

[0083] A method for preparing a cobalt-based perovskite material in this embodiment includes the following steps:

[0084] (1) In an inert gas argon atmosphere glove box, CaO, CoO, RuO2 and NaClO4 oxidants were mixed uniformly in a molar ratio of 1:0.2:0.8:2 to obtain an initial mixed powder;

[0085] (2) pressing the initial mixed powder into a sheet so that the powder particles are fully in contact with each other to obtain a sheet sample, wherein the thickness of the sheet sample is 10 mm;

[0086] (3) placing the sheet sample in a gold capsule, sealing and wrapping it, placing it in the cavity of a six-sided press, and performing a high-temperature and high-pressure synthesis reaction at a pressure of 1 GPa, a temperature of 900° C., and a reaction time of 3 h to obtain a product;

[0087] (4) Taking the product out of the gold capsule and grinding it into a uniform powder to obtain the cobalt-based perovskite material.

[0088] The cobalt-based perovskite material prepared in this embodiment is cylindrical, with a diameter of 1 cm, a height of 1 cm, and a weight of 4 g.

[0089] The molecular formula of the cobalt-based perovskite material prepared in this example is CaCo 0.2 Ru 0.8 O3, the X-ray diffraction of the cobalt-based perovskite material prepared in this embodiment is as follows Figure 5 shown.

[0090] The crystal structure and magnetic properties of the cobalt-based perovskite material prepared in this example are basically the same as those in Example 1, and are not listed one by one due to limited space.

[0091] Example 4

[0092] The method for preparing a cobalt-based perovskite material in this embodiment is the same as that in Embodiment 1, except that in step (1), x=0.9.

[0093] The molecular formula of the cobalt-based perovskite material prepared in this example is CaCo 0.1 Ru 0.9 O3.

[0094] Example 5

[0095] The method for preparing a cobalt-based perovskite material in this embodiment is the same as that in Embodiment 1, except that in step (1), x=0.1.

[0096] The molecular formula of the cobalt-based perovskite material prepared in this example is CaCo 0.9 Ru 0.1 O3.

[0097] Example 6

[0098] The method for preparing a cobalt-based perovskite material in this embodiment is the same as that in Embodiment 1, except that in step (3), the temperature of the high-pressure reaction is 800° C. and the time is 10 h.

[0099] The molecular formula of the cobalt-based perovskite material prepared in this example is CaCo 0.5 Ru 0.5 O3.

[0100] Comparative Example 1

[0101] The preparation method of a cobalt-based perovskite material in this comparative example is the same as that in Example 1, except that in step (1), in an inert gas argon atmosphere glove box, using CaO and CoO as raw materials and KClO4 as an oxidant, the CaO and CoO raw materials and the KClO4 oxidant are mixed in a molar ratio of CaO:CoO:KClO4=1:1:0.5, and the above powders are evenly mixed to obtain an initial mixed powder.

[0102] The product prepared in this comparative example was subjected to an X-ray diffraction test, and the results were as follows: Figure 6 As shown, the products are Ca2Co2O5, CaO2, etc., and no CaCoO3 material is prepared.

[0103] Comparative Example 2

[0104] The method for preparing a cobalt-based perovskite material in this comparative example is the same as that in Example 1, except that in step (1), y=0.4.

[0105] The product prepared in this comparative example was subjected to an X-ray diffraction test, and the results were as follows: Figure 7 As shown, only a small amount of CaCo is generated in the product 0.5 Ru 0.5 O3, contains a large amount of other impurities.

[0106] Comparative Example 3

[0107] The method for preparing a cobalt-based perovskite material in this comparative example is the same as that in Example 1, except that in step (1), the pressure is 0.8 GPa and the temperature is 750° C.

[0108] The product prepared in this comparative example was subjected to an X-ray diffraction test, and the results were as follows: Figure 8 As shown, there are many unknown impurities in the product, and no CaCo was prepared. 1-x Ru x O3 material.

[0109] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A cobalt-based perovskite material, characterized in that: The molecular formula of the cobalt-based perovskite material is CaCo 1-x Ru x O3, where 0.1≤x≤0.

9.

2. A method for preparing a cobalt-based perovskite material, characterized in that: The method comprises the following steps: (1) mixing CaO, CoO, RuO2 and an oxidant to obtain an initial mixed powder; (2) pressing the initial mixed powder into a sheet to obtain a sheet sample; (3) sealing and wrapping the surface of the sheet sample, placing it in a high-pressure synthesis device, and performing a high-temperature and high-pressure synthesis reaction to obtain a product; (4) Grinding the product to obtain the cobalt-based perovskite material.

3. The method for preparing a cobalt-based perovskite material according to claim 2, characterized in that: In step (1), the oxidant includes at least one of KClO4 or NaClO4.

4. The method for preparing a cobalt-based perovskite material according to claim 2, characterized in that: In step (1), the molar ratio of CaO, CoO, RuO2 and the oxidant is 1:1-x:x:y, wherein 0.1≤x≤0.9 and 0.5≤y≤2.

5. The method for preparing a cobalt-based perovskite material according to claim 2, characterized in that: In step (3), the sheet sample is sealed and packaged with a gold capsule or a platinum capsule.

6. The method for preparing a cobalt-based perovskite material according to claim 2, characterized in that: In step (3), the synthesis reaction pressure is 1-5 GPa, the temperature is 800-1200° C., and the reaction time is 0.1-10 h.

7. The method for preparing a cobalt-based perovskite material according to claim 2, characterized in that: In step (4), after grinding, cleaning and drying are also included.

8. The method for preparing a cobalt-based perovskite material according to claim 7, characterized in that: The cleaning is performed with deionized water.

9. The method for preparing a cobalt-based perovskite material according to claim 7, characterized in that: The drying temperature is 100-200°C and the drying time is 1-2h.

10. Use of the cobalt-based perovskite material according to claim 1 or the cobalt-based perovskite material prepared by the method of any one of claims 2 to 9 in electrochemistry.

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