Perovskite oxide material with heterojunction distributed on two-phase interface and application of perovskite oxide material in piezoelectric catalytic treatment of wastewater

Abstract

The invention discloses a perovskite oxide material with heterojunctions distributed on a two-phase interface and application of the perovskite oxide material in piezoelectric catalytic treatment of wastewater, and belongs to the technical field of inorganic non-metallic material preparation, mechanical energy utilization and environmental purification. The perovskite oxide material comprises a matrix phase, a second phase precipitated in the matrix phase and a heterojunction formed by the precipitated phase / matrix. The perovskite oxide material is prepared through the technical means of solid solution-quenching-aging treatment, and the problem that a heterojunction and a two-phase interface are difficult to construct on a large scale in an inorganic nonmetal powder material is solved; by constructing a heterojunction and a two-phase interface in the perovskite oxide material, the absorption and utilization rate of the perovskite oxide material to mechanical energy is improved, so that carriers are more effectively separated, and more carriers participate in an oxidation-reduction reaction for purifying and degrading model pollutants; and finally, the catalytic purification efficiency of the perovskite type oxide material is improved.

Description

Technical Field

[0001] This invention relates to the fields of inorganic non-metallic material preparation, mechanical energy utilization, and environmental purification technology, specifically to a perovskite oxide material having a heterojunction distributed at the interface between two phases and its application in piezoelectric catalytic treatment of wastewater. Background Technology

[0002] Water resources are among the most precious resources on Earth. Due to the growth of modern industrial activities and the increase in the global population, water pollution has become a global problem. The pollutants involved in water pollution mainly include the following categories: organic matter such as dyes, antibiotics, and pesticides; heavy metal ions such as As(V), Hg(II), and Cr(VI); and inorganic pollutants. 131 、Sr 90 U 235 These pollutants include radioactive nuclides and microorganisms. Most of these pollutants are toxic and difficult to degrade naturally, accumulating in the human body through the food chain and negatively impacting physical and mental health. Organic pollutants can cause lung and kidney damage, gastrointestinal disorders, and various cancers, and in severe cases, death. Various treatment methods have been researched to remove organic pollutants from water bodies, such as reverse osmosis, adsorption, and photoelectrocatalysis, which are widely used; however, further improvements in catalytic purification efficiency are still needed.

[0003] Catalytic purification of water pollutants has proven to be an effective method. Based on the energy source of the catalytic reaction, it can be classified into thermocatalysis, photocatalysis, and electrocatalysis. Piezoelectric catalysis is a novel and effective method for removing organic pollutants from water, proposed in recent years. Its core lies in the piezoelectric response of the catalytic material, which can absorb and utilize mechanical energy to promote carrier separation, increase carrier lifetime, regulate carrier energy, and promote the adsorption and desorption of organic pollutants on the catalyst surface. Ultimately, the degradation of organic pollutants is achieved through the active free radicals generated by the carriers. To date, ZnO, BaTiO3, BiFeO3, NaNbO3, and (K...) have been used... 0.5 Na 0.5 A series of piezoelectric catalysts, such as NbO3 and BiVO3, have been reported for the degradation of organic pollutants in water. However, in pursuit of piezoelectric catalysts with superior performance, modification methods such as doping, defect engineering, and the construction of heterojunctions have been used to improve the performance of piezoelectric catalysts.

[0004] Compared to single-phase modification methods such as doping and defect engineering, constructing two-phase heterojunctions can effectively improve energy utilization, regulate the redox performance of catalysts, and reduce carrier recombination rates. Common methods for constructing heterostructures include deposition, growth, and co-precipitation; however, methods that form heterojunctions by creating precipitates in the matrix are rarely reported. Precipitates are three-dimensional defects, first discovered in "hardened" aluminum alloys, primarily used to enhance the mechanical properties of metals; their application in inorganic non-metallic materials is rarely reported. Solid solution-precipitation refers to the process in material systems where the solid solubility-temperature relationship is positively correlated. When the temperature is raised above the solid solubility temperature, the solute can dissolve into the matrix; subsequent quenching rapidly cools the solid solution below the solution temperature, preventing solute atoms from precipitating, thus forming a supersaturated solid solution; finally, long-term aging below the solution temperature causes the supersaturated solid solution to gradually decompose, while the precipitates nucleate and grow in the matrix. The final products of the decomposition of supersaturated solid solutions generally include two phases: a matrix phase and a precipitated phase. These two phases form a heterojunction and a closely contacted two-phase interface, thus providing a theoretical basis for introducing precipitated phase / matrix heterojunctions and two-phase interfaces into materials. Summary of the Invention

[0005] The purpose of this invention is to provide a perovskite oxide material with a heterostructure distributed at the two-phase interface and its application in piezoelectric catalytic treatment of wastewater. This material is prepared through a multi-step solid-state reaction involving high-energy ball milling, calcination, sintering, solution treatment, quenching, and aging. The resulting powder material solves the problem of large-scale construction of two-phase heterostructures and interfaces in inorganic non-metallic powder catalytic materials. The built-in electric field introduced by the precipitated phase / matrix heterostructure and the two-phase interface acting as a rapid transport channel effectively promotes carrier separation and can be applied to the piezoelectric catalytic treatment of pollutants in wastewater.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A perovskite oxide material having a heterojunction distributed at a two-phase interface includes a matrix phase, a second phase precipitated in the matrix, and a precipitated phase / matrix heterojunction distributed at the two-phase interface.

[0008] Furthermore, the precipitated phase is formed by precipitating from the supersaturated solid solution matrix and forming a tightly connected precipitated phase / matrix heterojunction at the two-phase interface.

[0009] Furthermore, the volume ratio of the precipitated phase (second phase) to the matrix phase is (0.01 to 99.99):100, and the preferred volume ratio is (1 to 25):100.

[0010] Furthermore, the perovskite oxide material is in powder form with a particle size of 1 nm to 1 mm.

[0011] Furthermore, the perovskite oxide material is sodium lithium niobate powder, potassium sodium lithium niobate powder, or barium calcium titanate powder, wherein: the matrix phase of the sodium lithium niobate powder is NaNbO3 and the precipitated phase is LiNbO3, and the matrix phase of the potassium sodium lithium niobate powder is (K 0.5 Na 0.5 The NbO3 phase and the precipitated phase are LiNbO3, and the matrix phase of the barium calcium titanate powder is (Ba 0.88 Ca 0.12 TiO3, the precipitated phase is CaTiO3.

[0012] Furthermore, this perovskite oxide material is prepared by a multi-step solid-state reaction, and the specific preparation method includes the following steps:

[0013] (1) Initial high-energy ball milling: Weigh the required raw materials according to the chemical composition of the perovskite oxide material to be prepared, dry each raw material in a drying oven, and then transfer it into a high-energy ball mill jar. Add an appropriate amount of anhydrous ethanol and agate balls for ball milling. After ball milling, mixture I is obtained.

[0014] (2) Calcination treatment: The mixture I obtained in step (1) is placed in a drying oven and dried at 60°C, and then transferred to a muffle furnace for calcination treatment. The calcination temperature is 800-1200°C, the calcination time is 1-6h, and the heating rate is 1-10°C / min.

[0015] (3) Secondary high-energy ball milling: The product obtained after calcination in step (2) is transferred into a high-energy ball milling jar, and an appropriate amount of anhydrous ethanol and agate balls are added for ball milling. After ball milling, mixture II is obtained.

[0016] (4) Sintering treatment: The mixture II obtained in step (3) is placed in a drying oven and dried at 60°C. Then it is transferred to a tube furnace for ceramic sintering treatment. The sintering time is 1 to 6 hours and the heating rate is 1 to 10°C / min.

[0017] (5) Solution treatment: After sintering in step (4), the sample is ground and then transferred into a tube furnace for solution treatment. The solution treatment time is 1 to 6 hours and the heating rate is 1 to 10℃ / min.

[0018] (6) Quenching treatment: After the solution treatment in step (5) is completed, the sample is directly transferred into deionized water for water bath quenching treatment. The water bath temperature is 0-100℃.

[0019] (7) Three-stage high-energy ball milling: After the sample obtained by quenching in step (6) is placed in a drying oven and dried at 60°C, it is transferred to a high-energy ball milling jar, and an appropriate amount of anhydrous ethanol and agate balls are added for ball milling. After ball milling, a mixture III is obtained.

[0020] (8) Aging treatment: The mixture III obtained after ball milling in step (7) is transferred into a muffle furnace for aging treatment. The aging time is 4 to 24 hours and the heating rate is 1 to 10 °C / min. After aging treatment, the perovskite oxide material with heterojunction distributed at the two-phase interface is obtained.

[0021] Furthermore, during the ball milling process in steps (1), (3) and (7), the ball milling speed is 250 r / min and the ball milling time is 12 h.

[0022] Furthermore, during the sintering treatment in step (4) and the solution treatment in step (5), when the perovskite oxide material is sodium lithium niobate powder, the sintering or solution treatment temperature is 1250-1350℃; when the perovskite oxide material is potassium sodium lithium niobate powder, the sintering or solution treatment temperature is 950-1050℃; and when the perovskite oxide material is barium calcium titanate powder, the sintering or solution treatment temperature is 1350-1450℃.

[0023] Furthermore, in step (8) during the aging process, the aging temperature is 450-750℃ when the perovskite oxide material is sodium lithium niobate powder, 450-650℃ when the perovskite oxide material is potassium sodium lithium niobate powder, and 1150-1250℃ when the perovskite oxide material is barium calcium titanate powder.

[0024] Furthermore, the perovskite oxide material with heterojunctions distributed at the two-phase interface is applied to the piezoelectric catalytic degradation of pollutants in water. Under mechanical pressure source (ultrasound) conditions, the perovskite oxide material with heterojunctions distributed at the two-phase interface exhibits superior degradation and purification performance compared to perovskite oxide materials without heterojunctions distributed at the two-phase interface.

[0025] Furthermore, the application process of this perovskite oxide material is as follows: a certain amount of perovskite oxide material with heterojunctions distributed at the interface of two phases is added to water containing pollutants. After stirring evenly to reach adsorption and dissociation equilibrium, the water is ultrasonically treated. The cavitation bubbles generated by the ultrasound break down to provide a local "hot spot" or generate high pressure, which excites the charge carriers located in the valence band to the conduction band. Subsequently, the built-in electric field introduced by the heterostructure of the precipitated phase / matrix in the material and the interface of the two phases serve as a fast transport channel to regulate and promote the separation of charge carriers. Finally, the charge carriers enter the solution to participate in the oxidation-reduction reaction of pollutants in the water, realizing the catalytic purification and degradation process.

[0026] The advantages and beneficial effects of this invention are as follows:

[0027] 1. This invention prepares perovskite oxide materials with precipitated phase / matrix heterojunctions and two-phase interfaces by using a multi-step solid-phase reaction of solution-quenching-aging, which solves the problem of difficulty in constructing heterojunctions and interfaces distributed at the two-phase interface in inorganic non-metallic powder catalytic materials on a large scale.

[0028] 2. This invention improves the utilization rate of mechanical energy by constructing a heterojunction in the perovskite oxide material to introduce a built-in electric field; and the two-phase interface serves as a fast transport channel, effectively promoting carrier separation; thus participating more in the redox reaction of the purification and degradation model pollutants, thereby improving the catalytic purification efficiency of the perovskite oxide material. Attached Figure Description

[0029] Figure 1 The X-ray diffraction patterns are those of the sodium niobate lithium powder catalyst materials prepared in Example 1, with and without precipitated phases.

[0030] Figure 2 This is a comparison diagram of the piezoelectric catalytic degradation of methyl orange by lithium sodium niobate powder catalytic materials with and without precipitated phases prepared in Example 1.

[0031] Figure 3 The X-ray diffraction patterns are those of the potassium sodium niobate lithium powder catalyst materials prepared in Example 2, with and without precipitated phases.

[0032] Figure 4 This is a comparison diagram of the piezoelectric catalytic degradation of methyl orange by lithium potassium sodium niobate powder catalytic materials with and without precipitated phases prepared in Example 2.

[0033] Figure 5 The X-ray diffraction patterns are those of barium calcium titanate powder catalysts with and without precipitated phases prepared in Example 3.

[0034] Figure 6 This is a comparison diagram of the piezoelectric catalytic degradation of methyl orange by barium calcium titanate powder catalytic materials with and without precipitated phases prepared in Example 3.

[0035] Figure 7 The results are TEM characterization results of the sodium niobate lithium powder catalyst material with precipitated phase and heterojunction distributed at the interface between the two phases prepared in Example 1.

[0036] Figure 8 The results are TEM characterization results of the potassium sodium niobate lithium powder catalyst material prepared in Example 2, which has a precipitated phase and a heterojunction distributed at the interface between the two phases.

[0037] Figure 9 The results are TEM characterization results of the barium calcium titanate powder catalytic material with precipitated phase and heterojunction distributed at the interface between the two phases prepared in Example 3. Detailed Implementation

[0038] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] In the following examples, the performance of the perovskite oxide material with a heterojunction of precipitated phase / matrix distributed at the two-phase interface was tested using methyl orange solution as a model water pollutant for comparative experiments. Ultrasound was used as the mechanical energy source to provide activation energy for the degradation of methyl orange by the perovskite oxide catalytic material, and the catalytic purification performance of the perovskite oxide material was systematically studied. Specifically, a certain mass of perovskite oxide material with a heterojunction of precipitated phase / matrix distributed at the two-phase interface was added to an aqueous solution containing 1-50 ppm of the model pollutant methyl orange. After stirring until adsorption and dissociation equilibrium was reached, the solution was subjected to ultrasonic treatment, and methyl orange underwent a redox reaction to achieve the catalytic purification and degradation process. Specifically, 0.01–10 g of perovskite oxide material was added per liter of the model pollutant MO solution, the MO content in the model pollutant MO solution was 1-50 ppm, and the ultrasonic power used in the catalytic treatment was 220 W, the ultrasonic frequency was 40 kHz, and the ultrasonic treatment time was 15-25 min.

[0040] Example 1:

[0041] This embodiment describes the preparation of a perovskite oxide material with a heterojunction between the precipitated phase and the matrix at the two-phase interface, namely lithium sodium niobate powder. The matrix phase is NaNbO3, and the precipitated phase is LiNbO3, with a volume ratio of approximately 9:1. The specific preparation steps are as follows:

[0042] (1) High-energy ball milling: Sodium carbonate, lithium carbonate and niobium pentoxide were placed in a drying oven and dried at 120°C for 3 hours. 2.3924 g of dried sodium carbonate, 0.3625 g of lithium carbonate and 7.2451 g of niobium pentoxide were weighed and transferred into an agate grinding jar. An appropriate amount of agate balls and anhydrous ethanol were added. The mixture was ball milled at 250 r / min for 12 hours, with a 10-minute break after every 30 minutes of operation.

[0043] (2) Calcination treatment: The uniformly mixed material obtained after ball milling in step (1) is first placed in a drying oven and dried at 60°C, and then transferred to a muffle furnace for calcination. The calcination temperature is 850°C, the time is 4 hours, and the heating rate is 5°C / min.

[0044] (3) Secondary high-energy ball milling: The material obtained after calcination in step (2) is transferred into a high-energy ball milling jar, and an appropriate amount of agate balls and anhydrous ethanol are added. The ball milling is carried out at a speed of 250 r / min for 12 hours, with a 10-minute break every 30 minutes.

[0045] (4) Sintering treatment: The material obtained after ball milling in step (3) is placed in a drying oven and dried at 60°C. Then it is transferred to a tube furnace for ceramic sintering treatment. The sintering temperature is 1300°C, the time is 2h, and the heating rate is 5°C / min.

[0046] (5) Solution treatment: After grinding the sample obtained in step (4), the sample is transferred into a tube furnace for solution treatment. The solution temperature is 1300℃, the time is 2h, and the heating rate is 5℃ / min.

[0047] (6) Quenching treatment: After the solution treatment in step (5) is completed, the sample is directly transferred into deionized water for water bath quenching treatment at room temperature.

[0048] (7) Three high-energy ball millings: After drying the sample obtained in step (6) in a drying oven at 60°C, it was transferred to a high-energy ball milling jar and an appropriate amount of agate balls and anhydrous ethanol were added. The sample was ball milled at a speed of 250 r / min for 12 h, with a 10 min break after every 30 min of operation (the sample obtained after this ball milling does not have a precipitated phase).

[0049] (8) Aging treatment: The sample obtained after ball milling in step (7) was transferred into a muffle furnace for aging treatment. The aging process was as follows: first, the temperature was raised to 500℃ and held for 16 hours, and then the temperature was raised to 700℃ and held for 8 hours. The heating rate was 5℃ / min. After aging treatment, sodium niobate lithium catalyst powder with a heterojunction of precipitated phase / matrix phase distributed at the interface of the two phases was obtained.

[0050] (9) Weigh 20 mg of perovskite oxide material (the material with precipitated phase prepared in step (8) or the material without precipitated phase prepared in step (7)) and add it to 50 ml of aqueous solution containing 10 ppm of the model pollutant methyl orange. After stirring evenly to reach adsorption and dissociation equilibrium, the solution is subjected to ultrasonic treatment with an ultrasonic power of 220 W, a frequency of 40 kHz and an ultrasonic treatment time of 20 min. Methyl orange undergoes an oxidation-reduction reaction to achieve the catalytic purification and degradation process.

[0051] Figure 1 The X-ray diffraction patterns of the lithium sodium niobate powder material with precipitated phase and heterojunction prepared in step (8) and the lithium sodium niobate powder material without precipitated phase prepared in step (7) in this embodiment show that the matrix of the lithium sodium niobate catalyst material with precipitated phase is NaNbO3, space group Pmc21, and the precipitated phase is LiNbO3, space group R3c; the matrix of the lithium sodium niobate material without precipitated phase is NaNbO3, space group R3c.

[0052] Figure 7 The TEM characterization results of the sodium niobate lithium powder catalyst material with precipitated phase and heterojunction prepared in this embodiment show that the precipitated phase / matrix heterojunction is distributed at the interface between the two phases.

[0053] Figure 2 This is a comparison diagram of the piezoelectric catalytic degradation of methyl orange by lithium sodium niobate powder with precipitated phase and heterojunction prepared in step (8) and lithium sodium niobate powder without precipitated phase prepared in step (7) in this embodiment. The efficiency of the lithium sodium niobate catalyst with precipitated phase in piezoelectric degradation of 10 ppm methyl orange at 20 min is 47.5%; the efficiency of the lithium sodium niobate catalyst without precipitated phase in piezoelectric degradation of 10 ppm methyl orange at 20 min is 32.8%. The catalytic efficiency of the lithium sodium niobate catalyst with precipitated phase is improved by 45% compared with that without precipitated phase.

[0054] Example 2:

[0055] This embodiment describes the preparation of a potassium sodium niobate lithium catalytic material with a heterojunction of precipitated phase / matrix distributed at the two-phase interface. The matrix phase is (K 0.5 Na 0.5 The NbO3 phase, space group P4mm, and the precipitated phase are LiNbO3 phases, space group R3c. The specific preparation steps are as follows:

[0056] (1) High-energy ball milling: Potassium carbonate, sodium carbonate, lithium carbonate and niobium pentoxide were placed in a drying oven and dried at 160°C for 3 hours. 1.5780g of potassium carbonate, 1.2947g of sodium carbonate, 0.2301g of lithium carbonate and 6.8973g of niobium pentoxide were weighed and transferred into an agate grinding jar. An appropriate amount of agate balls and anhydrous ethanol were added. The mixture was ball milled at 250r / min for 12 hours, with a 10-minute break after every 30 minutes of operation.

[0057] (2) Calcination treatment: The uniformly mixed material obtained after ball milling in step (1) is first placed in a drying oven and dried at 60°C, and then transferred to a muffle furnace for calcination. The calcination temperature is 850°C, the time is 4 hours, and the heating rate is 5°C / min.

[0058] (3) Secondary high-energy ball milling: The material obtained after calcination in step (2) is transferred into a high-energy ball milling jar, and an appropriate amount of agate balls and anhydrous ethanol are added. The ball milling is carried out at a speed of 250 r / min for 12 hours, with a 10-minute break every 30 minutes.

[0059] (4) Sintering treatment: The material obtained after ball milling in step (3) is placed in a drying oven and dried at 60°C. Then it is transferred to a tube furnace for ceramic sintering treatment. The sintering temperature is 1000°C, the time is 2h, and the heating rate is 5°C / min.

[0060] (5) Solution treatment: After grinding the sample obtained in step (4), the sample is transferred into a tube furnace for solution treatment. The solution temperature is 1000℃, the time is 2h, and the heating rate is 5℃ / min.

[0061] (6) Quenching treatment: After the solution treatment in step (5) is completed, the sample is directly transferred into deionized water for water bath quenching treatment at room temperature.

[0062] (7) Three high-energy ball millings: After drying the sample obtained in step (6) in a drying oven at 60°C, it was transferred to a high-energy ball milling jar and an appropriate amount of agate balls and anhydrous ethanol were added. The sample was ball milled at a speed of 250 r / min for 12 h, with a 10 min break after every 30 min of operation (the sample obtained after this ball milling does not have a precipitated phase).

[0063] (8) Aging treatment: The sample obtained after ball milling in step (7) was transferred into a muffle furnace for aging treatment. The aging process was as follows: first, the temperature was raised to 500℃ and held for 24 hours, then cooled to room temperature, and then raised to 600℃ and held for 16 hours. The heating rate was 5℃ / min. After aging treatment, a potassium sodium niobate lithium catalyst material with a heterojunction of precipitated phase / matrix distributed at the interface of the two phases was obtained.

[0064] (9) Weigh 20mg of perovskite oxide material (the material with precipitated phase prepared in step (8) or the material without precipitated phase prepared in step (7)) and add it to 50ml of methyl orange aqueous solution with a concentration of 10ppm. After stirring evenly to reach adsorption and dissociation equilibrium, the solution is subjected to ultrasonic treatment with an ultrasonic power of 220W, a frequency of 40kHz and an ultrasonic treatment time of 20min. Methyl orange undergoes an oxidation-reduction reaction to achieve the catalytic purification and degradation process.

[0065] Figure 3 The X-ray diffraction patterns are shown for the lithium potassium sodium niobate powder material with precipitated phase and heterojunction prepared in step (8) of this embodiment and the lithium potassium sodium niobate powder catalyst material without precipitated phase prepared in step (7). The matrix of the lithium potassium sodium niobate catalyst material with precipitated phase is (K 0.5 Na 0.5 NbO3, space group P4mm, precipitated phase is LiNbO3, space group R3c; the matrix of the potassium sodium niobate lithium material without precipitated phase is (K 0.5 Na 0.5 )NbO3, space group P4mm.

[0066] Figure 8 The TEM characterization results of the potassium sodium lithium niobate powder catalyst material with precipitated phase and heterojunction prepared in this embodiment show that the precipitated phase / matrix heterojunction is distributed at the interface between the two phases.

[0067] Figure 4This is a comparison diagram of the piezoelectric catalytic degradation of methyl orange by lithium sodium niobate powder with precipitated phase and heterojunction prepared in step (8) and lithium potassium sodium niobate without precipitated phase prepared in step (7). The lithium potassium sodium niobate catalyst with precipitated phase achieved a piezoelectric degradation efficiency of 56.1% for 10 ppm methyl orange after 20 min; the lithium potassium sodium niobate catalyst without precipitated phase achieved a piezoelectric degradation efficiency of 49.8% for 10 ppm methyl orange after 20 min. The catalytic efficiency of the lithium potassium sodium niobate catalyst with precipitated phase is 13% higher than that of the lithium potassium sodium niobate catalyst without precipitated phase.

[0068] Example 3:

[0069] This embodiment describes the preparation of a barium calcium titanate catalytic material with a heterojunction of precipitated phase / matrix distributed at the two-phase interface. The matrix phase is (Ba 0.88 Ca 0.12 TiO3, space group P4mm, precipitated phase is CaTiO3, space group Pbnm, the specific preparation steps are as follows:

[0070] (1) High-energy ball milling: Place the raw materials calcium carbonate, barium carbonate and titanium dioxide in a drying oven and dry at 120℃ for 3h. Weigh 0.9894g of dried calcium carbonate, 5.8524g of barium carbonate and 3.1582g of titanium dioxide and transfer them into an agate grinding jar. Add an appropriate amount of agate balls and anhydrous ethanol and ball mill at 250r / min for 12h, stopping for 10min every 30min.

[0071] (2) Calcination treatment: The uniformly mixed material obtained after ball milling in step (1) is first placed in a drying oven and dried at 60°C, and then transferred to a muffle furnace for calcination. The calcination temperature is 1100°C, the time is 4h, and the heating rate is 5°C / min.

[0072] (3) Secondary high-energy ball milling: The material obtained after calcination in step (2) is transferred into a high-energy ball milling jar, and an appropriate amount of agate balls and anhydrous ethanol are added. The ball milling is carried out at a speed of 250 r / min for 12 hours, with a 10-minute break every 30 minutes.

[0073] (4) Sintering treatment: The material obtained after ball milling in step (3) is placed in a drying oven and dried at 60°C. Then it is transferred to a tube furnace for solution treatment. The sintering temperature is 1400°C, the time is 2h, and the heating rate is 5°C / min.

[0074] (5) Solution treatment: After grinding the sample obtained in step (4), the sample is transferred into a tube furnace for solution treatment. The solution temperature is 1400℃, the time is 2h, and the heating rate is 5℃ / min.

[0075] (6) Quenching treatment: After the solution treatment in step (5) is completed, the sample is directly transferred into deionized water for water bath quenching treatment at room temperature.

[0076] (7) Three high-energy ball millings: After drying the sample obtained in step (6) in a drying oven at 60°C, it was transferred to a high-energy ball milling jar and an appropriate amount of agate balls and anhydrous ethanol were added. The sample was ball milled at a speed of 250 r / min for 12 h, with a 10 min break after every 30 min of operation (the sample obtained after this ball milling does not have a precipitated phase).

[0077] (8) Aging treatment: The sample obtained after ball milling in step (7) was transferred into a muffle furnace for aging treatment. The aging process was as follows: the temperature was raised to 1200℃ and held for 24 hours, and then cooled to room temperature. After aging treatment, a barium calcium titanate catalyst material with a heterojunction of precipitated phase / matrix distributed at the interface of the two phases was obtained.

[0078] (9) Weigh 20 mg of perovskite oxide material (the material with precipitated phase prepared in step (8) or the material without precipitated phase prepared in step (7)) and add it to 50 ml of aqueous solution containing 10 ppm of the model pollutant methyl orange. After stirring evenly to reach adsorption and dissociation equilibrium, the solution is subjected to ultrasonic treatment with an ultrasonic power of 220 W, a frequency of 40 kHz and an ultrasonic treatment time of 20 min. Methyl orange undergoes an oxidation-reduction reaction to achieve the catalytic purification and degradation process.

[0079] Figure 5 The X-ray diffraction patterns are shown for the barium calcium titanate powder material with precipitated phase and heterojunction prepared in step (8) and the barium calcium titanate powder catalytic material without precipitated phase prepared in step (7) in this embodiment. The matrix of the barium calcium titanate catalytic material with precipitated phase is (Ba 0.88 Ca 0.12 TiO3, space group P4mm, precipitated phase is CaTiO3, space group Pbnm; the matrix of the sodium lithium niobate material without precipitated phase is (Ba 0.88 Ca 0.12 TiO3, space group P4mm.

[0080] Figure 9 The TEM characterization results of the barium calcium titanate catalytic material with precipitated phase and heterojunction prepared in this embodiment show that the precipitated phase / matrix heterojunction is distributed at the interface between the two phases.

[0081] Figure 6This is a comparison diagram of the piezoelectric catalytic degradation of methyl orange by the barium calcium titanate powder with precipitated phase and heterojunction prepared in step (8) and the barium calcium titanate material without precipitated phase prepared in step (7). The efficiency of the barium calcium titanate catalytic material with precipitated phase in the piezoelectric degradation of 10 ppm methyl orange in 20 min is 47.9%; the efficiency of the barium calcium titanate catalytic material without precipitated phase in the piezoelectric degradation of 10 ppm methyl orange in 20 min is 45.6%. The catalytic efficiency of the barium calcium titanate catalytic material with precipitated phase is improved by 5% compared with that without precipitated phase.

[0082] The above embodiments are for reference only. Perovskite catalytic materials with precipitated phase / matrix heterojunctions and two-phase interfaces, as well as methods and applications for preparing precipitated phase / matrix heterojunctions and two-phase interface powder materials by solid solution-aging, are all within the scope of protection of this patent.

Claims

1. A perovskite oxide material having a heterostructure distributed at the interface of two phases, characterized in that: The material comprises a matrix phase, a second phase precipitated in the matrix, and a precipitated phase / matrix heterojunction distributed at the interface between the two phases.

2. The perovskite oxide material having a heterojunction distributed at the two-phase interface according to claim 1, characterized in that: The precipitated phase is formed by precipitating from a supersaturated solid solution matrix and forming a tightly connected precipitated phase / matrix heterojunction at the two-phase interface.

3. The perovskite oxide material having a heterojunction distributed at the two-phase interface according to claim 1, characterized in that: The volume ratio of the precipitated phase (second phase) to the matrix phase is (0.01~99.99):100; the perovskite oxide material is in powder form with a particle size of 1nm~1mm.

4. The perovskite oxide material having a heterojunction distributed at the two-phase interface according to claim 1 or 2, characterized in that: The perovskite oxide material is sodium lithium niobate powder, potassium sodium lithium niobate powder, or barium calcium titanate powder, wherein: the matrix phase of sodium lithium niobate powder is NaNbO3 and the precipitated phase is LiNbO3, and the matrix phase of potassium sodium lithium niobate powder is (K 0.5 Na 0.5 The NbO3 phase and the precipitated phase are LiNbO3, and the matrix phase of the barium calcium titanate powder is (Ba 0.88 Ca 0.12 TiO3, the precipitated phase is CaTiO3.

5. The perovskite oxide material having a heterojunction distributed at the two-phase interface according to claim 1, characterized in that: This perovskite oxide material is prepared by a multi-step solid-state reaction, and the specific preparation method includes the following steps: (1) Initial high-energy ball milling: Weigh the required raw materials according to the chemical composition of the perovskite oxide material to be prepared, dry each raw material in a drying oven, and then transfer it into a high-energy ball mill jar. Add an appropriate amount of anhydrous ethanol and agate balls for ball milling. After ball milling, mixture I is obtained. (2) Calcination treatment: The mixture I obtained in step (1) is placed in a drying oven and dried at 60°C, and then transferred to a muffle furnace for calcination treatment. The calcination temperature is 800-1200°C, the calcination time is 1-6h, and the heating rate is 1-10°C / min. (3) Secondary high-energy ball milling: The product obtained after calcination in step (2) is transferred into a high-energy ball milling jar, and an appropriate amount of anhydrous ethanol and agate balls are added for ball milling. After ball milling, mixture II is obtained. (4) Sintering treatment: The mixture II obtained in step (3) is placed in a drying oven and dried at 60°C. Then it is transferred to a tube furnace for ceramic sintering treatment. The sintering time is 1 to 6 hours and the heating rate is 1 to 10°C / min. (5) Solution treatment: After sintering in step (4), the sample is ground and then transferred into a tube furnace for solution treatment. The solution treatment time is 1 to 6 hours and the heating rate is 1 to 10℃ / min. (6) Quenching treatment: After the solution treatment in step (5) is completed, the sample is directly transferred into deionized water for water bath quenching treatment. The water bath temperature is 0-100℃. (7) Three-stage high-energy ball milling: After the sample obtained by quenching in step (6) is placed in a drying oven and dried at 60°C, it is transferred to a high-energy ball milling jar, and an appropriate amount of anhydrous ethanol and agate balls are added for ball milling. After ball milling, a mixture III is obtained. (8) Aging treatment: The mixture III obtained after ball milling in step (7) is transferred into a muffle furnace for aging treatment. The aging time is 4 to 24 hours and the heating rate is 1 to 10 °C / min. After aging treatment, the perovskite oxide material with heterojunction distributed at the two-phase interface is obtained.

6. The perovskite oxide material having a heterojunction distributed at the two-phase interface according to claim 5, characterized in that: During the ball milling process in steps (1), (3) and (7), the ball milling speed is 250 r / min and the ball milling time is 12 h.

7. The perovskite oxide material having a heterojunction distributed at the two-phase interface according to claim 5, characterized in that: During the sintering process in step (4) and the solution treatment process in step (5), the sintering or solution treatment temperature is 1250-1350℃ when the perovskite oxide material is sodium lithium niobate powder, 950-1050℃ when the perovskite oxide material is potassium sodium lithium niobate powder, and 1350-1450℃ when the perovskite oxide material is barium calcium titanate powder.

8. The perovskite oxide material having a heterojunction distributed at the two-phase interface according to claim 5, characterized in that: In step (8) during the aging process, the aging temperature is 450-750℃ when the perovskite oxide material is sodium lithium niobate powder, 450-650℃ when the perovskite oxide material is potassium sodium lithium niobate powder, and 1150-1250℃ when the perovskite oxide material is barium calcium titanate powder.

9. The application of the perovskite oxide material with a heterojunction distributed at the two-phase interface as described in claim 1 in the piezoelectric catalytic treatment of wastewater, characterized in that: This perovskite oxide material is used for piezoelectric catalytic degradation of pollutants in water. The perovskite oxide material distributed in the heterojunction at the two-phase interface exhibits superior degradation and purification performance under mechanical pressure (ultrasound) conditions compared to perovskite oxide materials without the heterojunction at the two-phase interface.

10. The application of the perovskite oxide material with a heterojunction distributed at the two-phase interface as described in claim 9 in the piezoelectric catalytic treatment of wastewater, characterized in that: The application process of this perovskite oxide material is as follows: A certain amount of perovskite oxide material with heterojunctions distributed at the interface of two phases is added to water containing pollutants. After stirring evenly to reach adsorption and dissociation equilibrium, the water is ultrasonically treated. The cavitation bubbles generated by the ultrasound break down to provide a local "hot spot" or generate high pressure, which excites the charge carriers located in the valence band to the conduction band. Subsequently, the built-in electric field introduced by the heterostructure of the precipitated phase / matrix in the material and the interface of the two phases serve as a fast transport channel to regulate and promote the separation of charge carriers. Finally, the charge carriers enter the solution to participate in the oxidation-reduction reaction of pollutants in the water, realizing the catalytic purification and degradation process.

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