Multicomponent high-entropy perovskite oxynitride nanopowder, method of making and applications thereof

Abstract

The application discloses multi-element high-entropy perovskite oxynitride nanopowder and a preparation method and application thereof, and relates to the technical field of photocatalysis, and in particular to a preparation method of multi-element high-entropy perovskite oxynitride nanopowder.The preparation method comprises the following steps: dissolving calcium carbonate powder, strontium carbonate powder, barium carbonate powder, europium sesquioxide powder, tantalum pentoxide powder and first urea in anhydrous ethanol, performing ball milling to obtain mixed slurry, drying the mixed slurry to obtain mixed precursor powder, heating the mixed precursor powder to 1100 DEG C to 1400 DEG C in a protective atmosphere to perform calcination, cooling to room temperature, and performing ammoniation on the obtained multi-element high-entropy perovskite oxynitride nanopowder initial powder in the protective atmosphere by using second urea to obtain multi-element high-entropy perovskite oxynitride nanopowder CaSrBaEuTa(O,N)3.The preparation method has the advantages of low cost, short time consumption, high product purity and the like, and the prepared product can be applied to the field of photocatalytic water oxygen production and has a very high oxygen production rate.

Description

Technical Field

[0001] This invention relates to the field of high-performance ceramic material preparation technology, specifically to multi-element high-entropy perovskite oxynitride nanopowder, its preparation method, and its application. Background Technology

[0002] High-entropy materials are typically formed by the solid solution of multiple components in equal or near-equal proportions. They possess structural characteristics and performance properties distinct from traditional materials, and are expected to find wide applications in aerospace, new energy electronic devices, and nuclear energy. High-entropy alloys (HEAs) exhibit superior properties unmatched by traditional materials due to their thermodynamic high-entropy effect, kinetic slow diffusion effect, structural lattice distortion effect, and performance "cocktail effect," making them a major focus of materials research in recent years.

[0003] High-entropy perovskite oxides are multi-component oxides with a single solid solution structure, composed of five or more oxides in equimolar or near-equimolar amounts. Introducing nitrogen atoms into the crystal structure of high-entropy perovskite ABO3 oxides can synthesize multi-component high-entropy perovskite oxynitrides. However, current processes for synthesizing oxynitride powders are limited and time-consuming, typically requiring tens of hours. Furthermore, to improve yield, samples need to be removed and ground several times during the process, making it complex. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a low-cost, short-time, high-purity, and excellent photocatalytic oxygen production performance multi-element high-entropy perovskite oxynitride nanopowder, its preparation method and application.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A method for preparing multi-component high-entropy perovskite oxynitride nanopowder includes the following steps: (1) Dissolve calcium carbonate powder, strontium carbonate powder, barium carbonate powder, europium trioxide powder, tantalum pentoxide powder and first urea in anhydrous ethanol and ball mill to obtain a mixed slurry; wherein, the addition ratio of calcium carbonate powder, strontium carbonate powder, barium carbonate powder, europium trioxide powder, tantalum pentoxide powder, first urea and anhydrous ethanol is 2mol∶2mol∶2mol∶1mol∶1mol∶6mol~12mol∶200mL~300mL; (2) The mixed slurry obtained in step (1) is dried to obtain mixed precursor powder; (3) The mixed precursor powder obtained in step (2) is heated to 1100℃~1400℃ in a protective atmosphere for calcination. The heating rate is 100℃ / min~500℃ / min and the holding time is 1min~10min. Then it is cooled to room temperature to obtain the initial powder of multi-element high-entropy perovskite oxynitride nanopowder. The initial powder of multi-element high-entropy perovskite oxynitride nanopowder is aminated with a second urea in a protective atmosphere to obtain multi-element high-entropy perovskite oxynitride nanopowder CaSrBaEuTa(O,N)3.

[0007] In the preferred method for preparing the above-mentioned multi-element high-entropy perovskite oxynitride nanopowder, step (3) involves heating to 1200℃~1300℃ and holding for 1min~5min.

[0008] In the preferred method for preparing the above-mentioned multi-element high-entropy perovskite oxynitride nanopowder, the ammoniation process in step (3) is as follows: a crucible is prepared, a partition layer is provided inside the crucible, and the partition layer is provided with pores. The partition layer divides the crucible into an upper chamber and a lower chamber. The initial powder of the multi-element high-entropy perovskite oxynitride nanopowder is placed in the upper chamber, and a second urea is placed in the lower chamber. The mass of the second urea is 1 to 5 times the mass of the initial powder of the multi-element high-entropy perovskite oxynitride nanopowder. The temperature is increased to 1000°C to 1300°C at a rate of 100°C / min to 400°C / min in a protective atmosphere and held for 5 min to 30 min. The ammonia gas generated by the second urea enters the upper chamber through the pores to ammoniate the initial powder of the multi-element high-entropy perovskite oxynitride nanopowder.

[0009] More preferably, in step (3), during the ammoniation process, the mass of the second urea is 2 to 4 times the initial mass of the multi-element high-entropy perovskite oxynitride nanopowder, and the temperature is increased to 1100°C to 1200°C at a rate of 100°C / min to 300°C / min in a protective atmosphere and held for 10 min to 20 min.

[0010] In the above-mentioned method for preparing multi-element high-entropy perovskite oxynitride nanopowder, preferably, in step (3), the protective atmosphere is one or more of nitrogen, helium and argon, and the protective atmosphere of the calcination is consistent with the protective atmosphere of the ammoniation.

[0011] In the above-mentioned method for preparing multi-element high-entropy perovskite oxynitride nanopowder, preferably, in step (1), the ball milling time is 1h to 24h; in step (2), the drying process is divided into two steps, the drying temperature of the first step is 50℃ to 80℃ and the drying time is 1h to 4h, and the drying temperature of the second step is 90℃ to 150℃ and the drying time is 2h to 8h.

[0012] More preferably, in step (2), the drying process is divided into two steps: the drying temperature of the first step is 60℃~70℃ and the drying time is 2h~3h; the drying temperature of the second step is 100℃~130℃ and the drying time is 3h~5h.

[0013] As a general technical concept, the present invention also provides a method for preparing the above-mentioned multi-element high-entropy perovskite oxynitride nanopowder, resulting in multi-element high-entropy perovskite oxynitride nanopowder.

[0014] As a general technical concept, the present invention also provides an application of the above-mentioned multi-element high-entropy perovskite oxynitride nanopowder in the field of photocatalytic water oxygen production.

[0015] In the above applications, preferably, the photocatalysis is visible light photocatalysis.

[0016] Compared with the prior art, the advantages of the present invention are as follows: 1. This invention provides a method for preparing multi-component high-entropy perovskite oxynitride nanopowder. Using CaCO3, SrCO3, BaCO3, Eu2O3, and Ta2O5 as raw materials and inexpensive urea (CO(NH2)2) as the nitrogen source, CaSrBaEuTa(O,N)3 nanopowder is synthesized within minutes. Existing technologies use flowing ammonia as the nitrogen source, resulting in a gas-solid reaction with slow diffusion and often confined to the gas-solid interface, leading to incomplete reaction. However, using urea as the nitrogen source results in a solid-phase reaction with complete reaction, allowing for the preparation of CaSrBaEuTa(O,N)3 oxynitride at lower temperatures. Compared with traditional methods, this method offers advantages such as low cost, short reaction time, simple operation, and high product purity.

[0017] 2. In preparing multi-component high-entropy perovskite oxynitride nanopowder, the present invention employs a rapid ammoniation method. The initially prepared tantalum-based multi-component high-entropy oxynitride nanopowder is ammonified using a crucible with a specific structure. During this process, the ammonia gas generated by urea increases the nitrogen content of the product and can also effectively remove residual carbon generated by incomplete decomposition of urea in the reaction mixture, resulting in higher product purity (above 97%).

[0018] 3. The present invention employs a relatively fast heating rate (100-500℃ / min) in both the calcination of the mixed precursor powder and the ammoniation process. This is because urea can decompose at relatively low temperatures. To avoid premature loss of nitrogen source, a faster heating rate is adopted, which is beneficial to increase the degree of nitridation when the reaction system reaches a higher temperature for the formation of oxynitrides, thereby increasing the degree of ammoniation in the subsequent process and ultimately improving the purity of the product.

[0019] 4. In the process of preparing multi-element high-entropy perovskite oxynitride nanopowder, the slurry is dried using a two-step drying method. Because the slurry contains a relatively large amount of ethanol, and the ethanol vaporization temperature is low, in order to avoid the temperature of the vaporized ethanol being too high in the small drying chamber, the temperature of the first drying process is low, controlled below 80°C, to dry and evaporate the ethanol first. The second step is carried out at a higher temperature (above 90°C) to ensure that the slurry is thoroughly dried.

[0020] 5. The multi-component high-entropy perovskite oxygen-nitrogen compound nanopowder provided by this invention is CaSrBaEuTa(O,N)3. The five cations are relatively uniformly distributed at the microscopic level, forming a pure phase, which has excellent photocatalytic oxygen production performance in water. It showed extremely high yield in visible light photocatalytic water splitting oxygen production test and has broad application prospects. Attached Figure Description

[0021] Figure 1 Optical photographs and XRD patterns of the multi-element high-entropy perovskite oxynitride nanopowder prepared in Example 1 of this invention.

[0022] Figure 2 This is a SEM image showing the microstructure of the multi-element high-entropy perovskite oxynitride nanopowder prepared in Example 1 of this invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0024] Example 1 A method for preparing multi-component high-entropy perovskite oxynitride nanopowder according to the present invention includes the following steps: (1) Dissolve 2.00 g (0.02 mol) calcium carbonate powder, 2.95 g (0.02 mol) strontium carbonate powder, 3.95 g (0.02 mol) barium carbonate powder, 3.52 g (0.01 mol) europium trioxide powder, 4.42 g (0.01 mol) tantalum pentoxide powder and 6.00 g (0.1 mol) urea (i.e., first urea) in 200 mL of anhydrous ethanol and ball mill for 4 h to obtain a mixed slurry; (2) The mixed slurry obtained in step (1) is first dried at 70°C for 4 hours, and then dried at 100°C for 6 hours to obtain mixed precursor powder; (3) The mixed precursor powder obtained in step (2) is placed in the first crucible (a conventional crucible) and calcined in a nitrogen atmosphere at 1300°C. The heating rate is 100°C / min, and the holding time is 1min. Then, it is cooled to room temperature in the furnace to obtain the initial powder of multi-element high-entropy perovskite oxynitride nanoparticles. The initial powder of multi-element high-entropy perovskite oxynitride nanoparticles is then placed in the second crucible. The second crucible is provided with a partition layer with pores. The partition layer divides the crucible into an upper chamber and a lower chamber. The initial titanium dioxide oxynitride nanopowder was placed in the upper chamber, and urea (i.e., the second urea) was placed in the lower chamber. The mass of the urea was three times the mass of the initial multi-element high-entropy perovskite oxynitride nanopowder. The mixture was rapidly heated to 1200℃ in a nitrogen atmosphere at 300℃ / min using a discharge plasma device and held at that temperature for 15min. The ammonia gas generated by the urea entered the upper chamber through the pores and underwent rapid ammoniation to obtain high-purity (97.34%) multi-element high-entropy perovskite oxynitride nanopowder CaSrBaEuTa(O,N)3.

[0025] The phase composition and microstructure of the multi-element high-entropy perovskite oxynitride nanoparticles in this embodiment are as follows: Figure 1 and Figure 2 As shown: by Figure 1 It can be seen that its phase is almost pure phase CaSrBaEuTa(O,N)3, the color is gray, and the product has a uniform morphology and size with a grain size of about 100nm to 300nm.

[0026] The multi-element high-entropy perovskite oxygen nitride nanoparticles prepared in this embodiment were applied to photocatalytic water oxygen production. Water was decomposed under visible light catalysis to produce oxygen. The test results are shown in Table 1. The CaSrBaEuTa(O,N)3 oxygen nitride prepared in this embodiment has an extremely high oxygen production rate.

[0027] Comparative Example 1 The preparation method of a high-entropy material is basically the same as that in Example 1, except that: The raw materials do not contain urea, and the products prepared are high-entropy oxides containing five elements: Ca, Sr, Ba, Eu, and Ta.

[0028] The oxygen production rate of the five-membered high-entropy oxide prepared in this comparative example, which splits water to produce oxygen under visible light catalysis, was only 1.43 μmol·g⁻¹ in the first hour. -1 ·h -1 The oxygen production rate of this comparative product under visible light catalysis was significantly lower than that of Example 1. This is because perovskite oxynitrides have strong absorption in the visible light region and can be used as catalysts for decomposing organic molecules and for visible light-catalyzed water splitting reactions.

[0029] Table 1. Photocatalytic oxygen production rates of products from Example 1 and Comparative Example 1

[0030] Comparative Example 2 A method for preparing multi-component high-entropy perovskite oxynitride nanopowder includes the following steps: (1) Dissolve 2.00g (0.02mol) calcium carbonate powder, 2.95g (0.02mol) strontium carbonate powder, 3.95g (0.02mol) barium carbonate powder, 3.52g (0.01mol) europium trioxide powder, 4.42g (0.01mol) tantalum pentoxide powder and 6.00g (0.1mol) urea in 200mL of anhydrous ethanol and ball mill for 4h to obtain a mixed slurry; (2) The mixed slurry obtained in step (1) is first dried at 70°C for 4 hours, and then dried at 100°C for 6 hours to obtain mixed precursor powder; (3) The mixed precursor powder obtained in step (2) is placed in a conventional crucible and calcined at 1300°C in a nitrogen atmosphere. The heating rate is 100°C / min and the holding time is 1min. Then, it is cooled to room temperature in the furnace to obtain multi-element high-entropy perovskite oxynitride nanopowder with a purity of 90.41%.

[0031] Comparative Example 3 A method for preparing multi-component high-entropy perovskite oxynitride nanopowder according to the present invention includes the following steps: (1) Dissolve 2.00g (0.02mol) calcium carbonate powder, 2.95g (0.02mol) strontium carbonate powder, 3.95g (0.02mol) barium carbonate powder, 3.52g (0.01mol) europium trioxide powder, 4.42g (0.01mol) tantalum pentoxide powder and 6.00g (0.1mol) urea in 200mL of anhydrous ethanol and ball mill for 4h to obtain a mixed slurry; (2) The mixed slurry obtained in step (1) is first dried at 70°C for 4 hours, and then dried at 100°C for 6 hours to obtain mixed precursor powder; (3) The mixed precursor powder obtained in step (2) is placed in the first crucible (conventional crucible) and calcined at 1300°C in a nitrogen atmosphere at a heating rate of 10°C / min and a holding time of 1min. Then it is cooled to room temperature in the furnace to obtain a preliminary multi-element high-entropy perovskite oxynitride nanopowder. Then the nanopowder is placed in the second crucible (structure is the same as in Example 1) and rapidly heated to 1200°C at 300°C / min in a nitrogen atmosphere and held for 15min to perform rapid ammoniation to obtain multi-element high-entropy perovskite oxynitride nanopowder CaSrBaEuTa(O,N)3 with low purity (17.82%). This is because during the slow heating process, urea has decomposed and the reaction temperature has not yet been reached, and ammonia has dissipated.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing multi-component high-entropy perovskite oxynitride nanopowder, characterized in that, Includes the following steps: (1) Dissolve calcium carbonate powder, strontium carbonate powder, barium carbonate powder, europium trioxide powder, tantalum pentoxide powder and first urea in anhydrous ethanol and ball mill to obtain a mixed slurry; wherein, the addition ratio of calcium carbonate powder, strontium carbonate powder, barium carbonate powder, europium trioxide powder, tantalum pentoxide powder, first urea and anhydrous ethanol is 2mol∶2mol∶2mol∶1mol∶1mol∶6mol~12mol∶200mL~300mL; (2) The mixed slurry obtained in step (1) is dried to obtain mixed precursor powder; the drying process is divided into two steps, the drying temperature of the first step is 50℃~80℃ and the drying time is 1h~4h, the drying temperature of the second step is 90℃~150℃ and the drying time is 2h~8h. (3) The mixed precursor powder obtained in step (2) is heated to 1200℃~1300℃ in a protective atmosphere and calcined at a heating rate of 100℃ / min~500℃ / min and a holding time of 1min~5min. Then it is cooled to room temperature to obtain the initial powder of multi-element high-entropy perovskite oxynitride nanopowder. The initial powder of multi-element high-entropy perovskite oxynitride nanopowder is aminated in a protective atmosphere using a second urea to obtain multi-element high-entropy perovskite oxynitride nanopowder CaSrBaEuTa(O,N)3. During the amination process, the mass of the second urea is 2 to 4 times the mass of the initial powder of multi-element high-entropy perovskite oxynitride nanopowder. The temperature is raised to 1100℃~1200℃ in a protective atmosphere at a rate of 100℃ / min~300℃ / min and held for 10min~20min.

2. The method for preparing multi-element high-entropy perovskite oxynitride nanopowder according to claim 1, characterized in that, In step (3), the ammoniation process is as follows: a crucible is prepared, and a partition layer is provided inside the crucible. The partition layer is provided with pores, and the partition layer divides the crucible into an upper chamber and a lower chamber. The initial powder of the multi-element high-entropy perovskite oxynitride nanopowder is placed in the upper chamber, and the second urea is placed in the lower chamber. The ammonia gas generated by the second urea enters the upper chamber through the pores to ammoniate the initial powder of the multi-element high-entropy perovskite oxynitride nanopowder.

3. The method for preparing multi-element high-entropy perovskite oxynitride nanopowder according to claim 1 or 2, characterized in that, In step (3), the protective atmosphere is one or more of nitrogen, helium and argon, and the protective atmosphere for calcination is consistent with the protective atmosphere for ammoniation.

4. The method for preparing multi-element high-entropy perovskite oxynitride nanopowder according to claim 1 or 2, characterized in that, In step (1), the ball milling time is 1h to 24h.

5. The method for preparing multi-element high-entropy perovskite oxynitride nanopowder according to claim 4, characterized in that, In step (2), the drying process is divided into two steps. The drying temperature of the first step is 60℃~70℃ and the drying time is 2h~3h. The drying temperature of the second step is 100℃~130℃ and the drying time is 3h~5h.

6. A multi-element high-entropy perovskite oxynitride nanopowder prepared by a method according to any one of claims 1 to 5.

7. The application of the multi-element high-entropy perovskite oxynitride nanopowder as described in claim 6 in the field of photocatalytic water oxygen production.

8. The application according to claim 7, characterized in that, The photocatalysis is visible light photocatalysis.

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