A method of producing an oxygen-deficient perovskite material by ionizing radiation

Abstract

The application discloses a method for preparing a perovskite material rich in oxygen defects by ionizing radiation. The method comprises the following steps: weighing a certain amount of perovskite oxide material, dispersing the perovskite oxide material in a mixed solution of a hydroxyl shielding agent and deionized water, transferring the perovskite oxide material to a test tube after ultrasonic dispersion, sealing the test tube after oxygen removal by blowing in inert gas, and placing the test tube near an ionizing radiation source to prepare a perovskite material rich in oxygen defects. The ionizing radiation source used in the application includes one or more of a gamma ray source, a high-energy X-ray source, an accelerator source and a nuclear waste or space radiation source. The reaction is carried out at normal temperature and pressure, the process is simple, controllable, the content of oxygen defects introduced in the catalyst is adjusted by adjusting the absorbed dose, the whole process is green and environmentally friendly, has significant industrialization advantages, and is expected to be used for large-scale preparation of perovskite materials rich in oxygen defects, and has a wide application prospect in the industrial field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysis technology, in particular to a method for preparing oxygen-deficient perovskite material by ionizing radiation. BACKGROUND

[0002] Over-reliance and consumption of fossil fuels are releasing gases such as carbon dioxide (CO2) into the earth's atmosphere at an unprecedented rate, which has led to a series of climate and environmental problems. Therefore, how to efficiently and greenly reduce the increasing atmospheric CO2 level is one of the main challenges currently faced by mankind. Among a series of CO2 resource utilization methods, photocatalytic CO2 reduction reaction mainly relies on inexhaustible solar energy, and the catalytic process is green and environmentally friendly, which is considered to be the most promising CO2 resource utilization technology. Among them, the design of high-efficiency photocatalyst is the key in this reaction.

[0003] Perovskite materials have been widely concerned in photocatalytic reaction due to their excellent stability, non-toxicity, low cost, adjustable band gap and composition flexibility and other inherent advantages. Moreover, oxygen defect engineering and other modification methods are used to further improve the photocatalytic activity of such materials. However, traditional modification methods such as vacuum or inert atmosphere heat treatment, hydrogen atmosphere reduction, acid treatment or solvothermal process, etc. mostly require harsh conditions such as high temperature, high pressure and the participation of dangerous chemicals. Therefore, it is necessary to develop a new method that is simple to operate, green and environmentally friendly, and can introduce controllable oxygen defects.

[0004] High-energy rays have the advantages of high energy density, high efficiency and controllability, which provides a new idea, and has been applied to the modification of a variety of materials such as carbon materials, oxides, sulfides and MOF materials. Since the reaction is carried out at room temperature and pressure, the process is simple and controllable; the content of oxygen defects introduced in the catalyst is controlled by adjusting the absorption dose; the whole reaction process is green and environmentally friendly, and has significant industrialization advantages. Compared with other chemical methods, the concentration of oxygen defect structure produced in the radiation method in nanomaterials can reach a level that is difficult to achieve by chemical methods, and by combining with the properties of the material itself, the modified material can play excellent performance in various fields. SUMMARY

[0005] To solve the above problems, a method for preparing perovskite material rich in oxygen defects by ionizing radiation is provided. The method comprises the following steps: forming a mixed solution of perovskite material, a hydroxyl shielding agent, and deionized water, and stirring and dispersing the mixed solution uniformly. After vacuumizing and passing inert gas, the mixed solution is sealed and placed near an ionizing radiation source for irradiation treatment. Strong reducing substances generated by ionizing radiation of water produce oxygen defects in the perovskite material. The ionizing radiation source used in the method includes one or more of a gamma ray source, a high-energy X-ray source, an accelerator source, and a nuclear waste or space radiation source. The method is carried out at normal temperature and pressure, and has simple process and strong controllability. The content of oxygen defects introduced into the catalyst can be adjusted by adjusting the absorbed dose. The whole process is green and environmentally friendly, and has significant industrialization advantages. The method is expected to be used to prepare perovskite material rich in oxygen defects on a large scale, and has wide application prospects in the industrial field.

[0006] To achieve the above object, the present application provides the following technical scheme: a method for preparing perovskite material rich in oxygen defects by ionizing radiation, comprising the following steps: weighing a certain amount of perovskite oxide material, dispersing the perovskite oxide material in a mixed solution of a hydroxyl shielding agent and deionized water, transferring the mixed solution to a flask after ultrasonic dispersion, passing inert gas to remove oxygen, sealing the flask, and placing the flask near an ionizing radiation source to prepare perovskite material rich in oxygen defects.

[0007] Preferably, the ionizing radiation source provides energy for the reaction.

[0008] Preferably, the irradiation reaction is carried out at normal temperature and pressure.

[0009] Preferably, the chemical formula of the perovskite material is described as AB03, wherein the A-site element is usually one or more of alkali metals (K, Na), alkaline earth metals (Ca, Sr, Ba, etc.), or rare earth metals (La, Ce, Nd, etc.), and the B-site element is usually one or more of transition metals (Cu, Cr, Mn, Fe, Co, Ni, Ti, etc.).

[0010] Preferably, the selected hydroxyl shielding agent includes one or more of methanol, ethanol, isopropanol, tert-butyl alcohol, sodium formate, and sodium sulfite.

[0011] Preferably, the concentration of the perovskite material in the mixed solution is 0.1wt% to 5.0wt%.

[0012] Preferably, the concentration of the hydroxyl shielding agent in the mixed solution is 0.05mol / L to 2mol / L.

[0013] Preferably, the ionizing radiation source used includes one or more of a gamma ray source, a high-energy X-ray source, an accelerator source, and a nuclear waste or space radiation source.

[0014] Preferably, the ionizing radiation source dose rate is 0.1 kGy / h-10 kGy / h.

[0015] Preferably, the absorption dose of the perovskite material is at least 1 kGy.

[0016] The beneficial effects achieved by the present application are:

[0017] (1) The present application introduces oxygen defects in perovskite materials by ionizing radiation irradiation, which is carried out at normal temperature and pressure, simple and convenient to operate, and saves the preparation cost of the catalyst.

[0018] (2) The oxygen defect content in the oxygen defect-rich perovskite material catalyst provided by the present application can be controlled by adjusting the absorption dose, avoiding the difficulty in controlling the oxygen defect content, and efficiently preparing the oxygen defect-rich perovskite material.

[0019] (3) The oxygen defect-rich perovskite material provided by the present application has adjustable oxygen defect content, and the introduction of oxygen defects can improve the light absorption capacity of the material, enhance the separation and transfer of photo-generated electrons, inhibit the occurrence of recombination reaction, and promote the adsorption and activation of reaction substrates, thereby improving the performance of the photocatalytic CO2 reduction reaction. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0021] The present application provides a method for preparing an oxygen defect-rich perovskite material by ionizing radiation.

[0022] Oxygen defect embodiment 1

[0023] 100 mg of LaFeO3 material was weighed and dispersed in 20 mL of deionized water containing 0.02 mol of isopropanol, and after ultrasonic dispersion, it was transferred to a flask, deoxygenated by blowing in inert gas, sealed, and placed in the 60 Co source, the absorption dose was 10 kGy, the dose rate was 0.33 kGy / h, and the irradiation was carried out at normal temperature and pressure. After irradiation, the obtained material was used in the photocatalytic CO2 reduction reaction, and the results of chromatographic analysis showed that the photocatalytic reduction rate of CO2 to CO of the material was 7.9 μmol·g -1 ·h -1 , and the selectivity was 97.5%.

[0024] Embodiment 2

[0025] Take 20 mg of LaCrO3 material dispersed in 20 mL of deionized water containing 0.001 mol of sodium formate, ultrasonic dispersion is uniform, then transferred to a flask, sealed after oxygen is blown by inert gas, placed in 60 Co source, the absorbed dose is 20 kGy, the dose rate is 0.10 kGy / h, and the irradiation is carried out under normal temperature and pressure conditions. After the irradiation is completed, the obtained material is used in the photocatalytic CO2 reduction reaction, and the results of chromatographic analysis show that the photocatalytic reduction rate of CO2 to CO of the material is 11.3 μmol·g -1 ·h -1 , and the selectivity is 90.5%.

[0026] Example 3

[0027] Take 1.0 g of LaNiO3 material dispersed in 20 mL of deionized water containing 0.04 mol of sodium sulfite, ultrasonic dispersion is uniform, then transferred to a flask, sealed after oxygen is blown by inert gas, placed in an electron accelerator source, the absorbed dose is 500 kGy, the dose rate is 10.00 kGy / h, and the irradiation is carried out under normal temperature and pressure conditions. After the irradiation is completed, the obtained material is used in the photocatalytic CO2 reduction reaction, and the results of chromatographic analysis show that the photocatalytic reduction rate of CO2 to CO of the material is 29.1 μmol·g -1 ·h -1 , and the selectivity is 85.4%.

[0028] Example 4

[0029] Take 100 mg of LaFe 0.9 Co 0.1 O3 material dispersed in 20 mL of deionized water containing 0.02 mol of methanol, ultrasonic dispersion is uniform, then transferred to a flask, sealed after oxygen is blown by inert gas, placed in a high-energy X-ray source, the absorbed dose is 20 kGy, the dose rate is 10.0 kGy / h, and the irradiation is carried out under normal temperature and pressure conditions. After the irradiation is completed, the obtained material is used in the photocatalytic CO2 reduction reaction, and the results of chromatographic analysis show that the photocatalytic reduction rate of CO2 to CO of the material is 23.0 μmol·g -1 ·h -1 , and the selectivity is 94.6%.

[0030] Example 5

[0031] Take 100 mg of SrTiO3 material dispersed in 20 mL of deionized water containing 0.02 mol of ethanol, ultrasonic dispersion is uniform, then transferred to a flask, sealed after oxygen is blown by inert gas, placed in 60Co radiation source, the absorption dose is 60 kGy, the dose rate is 0.33 kGy / h, and the irradiation is carried out under normal temperature and pressure. After the irradiation is completed, the obtained material is used in the photocatalytic CO2 reduction reaction, and the result of chromatographic analysis is that the photocatalytic reduction rate of the material from CO2 to CO is 9.2 μmol·g -1 ·h -1 , and the selectivity is 93.3%.

[0032] Example 6

[0033] 100 mg of CaTiO3 material is weighed and dispersed in 20 mL of deionized water containing 0.02 mol of ethanol, and after ultrasonic dispersion, it is transferred to a flask, and after oxygen removal by blowing in inert gas, it is sealed and placed in 60 Co radiation source, the absorption dose is 20 kGy, the dose rate is 6.7 kGy / h, and the irradiation is carried out under normal temperature and pressure. After the irradiation is completed, the obtained material is used in the photocatalytic CO2 reduction reaction, and the result of chromatographic analysis is that the photocatalytic reduction rate of the material from CO2 to CO is 8.5 μmol·g -1 ·h -1 , and the selectivity is 92.1%.

[0034] Example 7

[0035] 100 mg of NaNbO3 material is weighed and dispersed in 20 mL of deionized water containing 0.02 mol of ethanol, and after ultrasonic dispersion, it is transferred to a flask, and after oxygen removal by blowing in inert gas, it is sealed and placed in 60 Co radiation source, the absorption dose is 20 kGy, the dose rate is 0.33 kGy / h, and the irradiation is carried out under normal temperature and pressure. After the irradiation is completed, the obtained material is used in the photocatalytic CO2 reduction reaction, and the result of chromatographic analysis is that the photocatalytic reduction rate of the material from CO2 to CO is 7.4 μmol·g -1 ·h -1 , and the selectivity is 93.2%.

[0036] Finally, it should be pointed out that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application 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 replacements to some technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing oxygen-defect-rich perovskite materials by ionizing radiation, characterized in that, The process includes the following steps: Weighing perovskite oxide material and dispersing it in a mixed solution of a hydroxyl shielding agent and deionized water, ultrasonically dispersing it evenly, transferring it to a vial, purging it with inert gas to remove oxygen, sealing it, and placing it near an ionizing radiation source to prepare oxygen-defect-rich perovskite material; the ionizing radiation source provides energy for the reaction; the irradiation reaction is carried out at room temperature and pressure; the chemical formula of the perovskite material is described as ABO3, wherein the A-site element is one or more of an alkali metal, alkaline earth metal, or rare earth metal, and the B-site element is one or more of a transition metal Cr, Co, Ni, or Ti; the selected hydroxyl shielding agent includes one or more of methanol, ethanol, isopropanol, tert-butanol, sodium formate, and sodium sulfite; The ionizing radiation source includes one or more of the following: gamma-ray source, high-energy X-ray source, and accelerator source. The dose rate of the ionizing radiation source is 0.1 kGy / h to 10 kGy / h; The absorbed dose of the perovskite material is at least 0.1 kGy.

2. The method for preparing oxygen-rich defect perovskite materials by ionizing radiation according to claim 1, characterized in that, The concentration of perovskite material in the mixed solution is 0.1 wt% to 5.0 wt%.

3. The method for preparing oxygen-rich defect perovskite materials by ionizing radiation according to claim 1, characterized in that, In the mixed solution, the concentration of the hydroxyl shielding agent is 0.05 mol / L to 2 mol / L.