Modified nitrogen-doped praseodymium iron oxide N-Pr0. 5Fe0. 5O2 nano-microsphere for Cr < 3 + > detection as well as preparation method and application thereof

Abstract

The invention discloses a modified nitrogen-doped praseodymium iron oxide N-Pr0. 5Fe0. 5O2 nano-microsphere for Cr < 3 + > detection as well as a preparation method and application of the modified nitrogen-doped praseodymium iron oxide N-Pr0. 5Fe0. 5O2 nano-microsphere, and solves the technical problem that accurate detection cannot be performed under low-voltage and low-content conditions in a Cr < 3 + > detection mode in the prior art. The preparation method comprises the following steps: firstly, preparing praseodymium iron oxide Pr0. 5Fe0. 5O2 nano-microspheres, adding praseodymium chloride, ferric trichloride, ammonium chloride and sodium hexadecyl benzene sulfonate into ethylene glycol, and reacting in a high-pressure reaction kettle to prepare the praseodymium iron oxide Pr0. 5Fe0. 5O2 nano-microspheres; the preparation method comprises the following steps: preparing Pr0. 5Fe0. 5O2 nano-microspheres, placing the Pr0. 5Fe0. 5O2 nano-microspheres at the downstream of a tubular furnace, placing melamine at the upstream of the tubular furnace, and realizing doping of non-metal nitrogen on the Pr0. 5Fe0. 5O2 nano-microspheres by utilizing thermal decomposition of the melamine, so as to prepare the nitrogen-doped praseodymium iron oxide N-Pr0. 5Fe0. 5O2 nano-microspheres. On the basis, a photoelectrochemical aptamer sensor is constructed for detecting trivalent chromium, and the Cr < 3 + > detection sensitivity and accuracy are remarkably improved by combining high-sensitivity detection of a photoelectrochemical sensing material with a nucleic acid aptamer specific recognition technology.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric active materials and photoelectric sensors, and is particularly concerned with a method for preparing Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres and their preparation method and application. Background Art

[0002] Chromium exists mainly in three valence states, namely Cr 2+ Cr 3+ and Cr 6+ These ionic forms have different stability and toxicity in the environment. 3+ It is relatively stable and has certain toxicity. Heavy metal Cr ions are widely present in the natural environment, such as rocks, soil and water. Hexavalent chromium is toxic to the human body and is considered a carcinogen. Long-term exposure to or ingestion of high concentrations of hexavalent chromium can cause damage to the lungs, kidneys and skeletal system. There have been many reports on the detection methods of hexavalent chromium. In contrast, trivalent chromium is less toxic, but it may also be converted into hexavalent chromium under certain conditions, thereby increasing its toxicity. Therefore, for Cr 3+ It also has important impacts on the environment and human health.

[0003] Traditionally, the detection of trivalent chromium ions is mainly done with the help of large instruments, most of which use atomic absorption spectroscopy, voltammetry, surface plasmon field enhanced resonance light scattering, and the recently popular colorimetric detection method. Although these methods can detect trivalent chromium ions, they are bulky or have low precision, and cannot accurately detect trivalent chromium ions in real time. In addition, the stability of traditional trivalent chromium photoelectric sensing platforms is generally poor, making it difficult to achieve accurate detection at low voltage and low content.

[0004] In the prior art, the photoelectrochemical aptamer sensor is a biosensing platform that combines photoelectrochemical high-sensitivity detection with aptamer-specific recognition technology. Under illumination conditions, photoelectric materials absorb light energy and generate photogenerated electrons. These electrons are transferred and transmitted, and finally reach the electrode and are converted into electrical signals. As a specific recognition element, the aptamer can bind to the target efficiently and specifically. When the target binds to the aptamer, the surface state of the photoelectric material or the electron transfer process will be changed, thereby causing changes in photocurrent or photovoltage. The photoelectrochemical sensor has the characteristics of low background signal and low detection limit, and can achieve high-sensitivity detection of the target. As a biological recognition element, the aptamer has high specificity and biocompatibility, and can achieve accurate recognition of the target. The equipment operation of the photoelectrochemical aptamer sensor is simple, and it is easy to realize automation and miniaturization. Compared with traditional detection methods, the photoelectrochemical aptamer sensor has lower cost and faster detection speed. Photoelectrochemical aptamer sensors have been widely used in bioanalysis, food testing, environmental protection and other fields. For example, in environmental testing, it can be used for harmful substances such as environmental estrogens and heavy metal ions; in biological analysis, it can be used to detect biomarkers such as cancer markers and disease-related proteins.

[0005] Therefore, it is urgent to provide a method that can realize Cr 3+ The photoelectrochemical aptamer sensing platform with high efficiency and high sensitivity can meet the actual detection needs. Summary of the invention

[0006] The present invention aims at the shortcomings and deficiencies in the prior art, and provides a method for realizing Cr 3+ The photoelectrochemical aptamer sensing platform can detect real-time monitoring and rapid response, and significantly improve the conductivity and stability of the photoelectric sensing platform, making it a low-cost, high-selectivity, high-sensitivity and high-precision platform for Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 Preparation method and application of O2 nanoparticles.

[0007] To achieve the above objectives, the present invention is implemented by the following technical solutions: 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The preparation method of O2 nanospheres comprises the following steps:

[0008] (1) Preparation of praseodymium iron oxide Pr 0.5 Fe 0.5 O2 nanospheres:

[0009] Weigh a certain mass ratio of praseodymium chloride PrCl, ferric chloride FeCl3, and ammonium chloride NH4Cl, and prepare a mixed solution with ethylene glycol. Add sodium hexadecylbenzene sulfonate to the mixed solution, dissolve it, and place it in a polytetrafluoroethylene-lined high-pressure reactor. React at 120℃-220℃ for 10h-20h to obtain praseodymium iron oxide Pr 0.5 Fe 0.5 O2 nanospheres;

[0010] (2) Preparation of nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres:

[0011] Using the thermal decomposition of melamine to achieve the Pr 0.5 Fe 0.5 The praseodymium iron oxide Pr prepared in step (1) is doped with non-metallic nitrogen on the O2 nanospheres. 0.5 Fe 0.5 O2 nanospheres are placed downstream of the tube furnace, and melamine is placed upstream of the tube furnace. They are heated in a nitrogen atmosphere. The upstream of the tube furnace is heated from room temperature to 600℃-1200℃ for insulation reaction, and the downstream of the tube furnace is heated from room temperature to 1000℃-1200℃ for insulation reaction to obtain nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres.

[0012] Preferably, the method further comprises step (3) of preparing amine-nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2-NH2:

[0013] The nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres and 3-aminopropyltriethoxysilane were dispersed in an ethanol solution and reacted at 80-135°C for 20-40 min. After centrifugation, washing and drying, amino-functionalized N-Pr 0.5 Fe 0.5 O2-NH2 nanospheres.

[0014] Preferably, step (1) prepares praseodymium iron oxide Pr 0.5 Fe 0.5 The specific steps of O2 nanospheres include the following:

[0015] Weigh praseodymium chloride, ferric chloride and ammonium chloride in a weight ratio of praseodymium chloride: ferric chloride: ammonium chloride = (2.2-10.0) g: (1.0-5.5) g: (2.0-10.0) g, add to 500 ml of ethylene glycol solvent to prepare a mixed solution, add 1.0 mg-100 mg of sodium hexadecylbenzene sulfonate to the mixed solution, and place in a polytetrafluoroethylene-lined autoclave after ultrasonic treatment, and react at 120° C.-220° C. for 10 h-20 h to obtain praseodymium iron oxide Pr 0.5 Fe 0.5 O2 nanospheres.

[0016] Preferably, step (2) prepares nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 In O2 nanospheres,

[0017] The praseodymium iron oxide Pr 0.5 Fe 0.5 The ratio of the amount of O2 nanospheres to the amount of melamine added is: (2.0-10.0) g: (10.0-25.0) g;

[0018] Under nitrogen atmosphere, heat the upstream of the tubular furnace from room temperature to 600°C-1200°C and keep it warm for 15min-60min, and heat the downstream of the tubular furnace from room temperature to 1000°C-1200°C and keep it warm for 60min-120min.

[0019] Preferably, step (3) prepares amino nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 10 mg of nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The O2 nanospheres were added with 20 ml of 3-aminopropyltriethoxysilane, dispersed in 100 ml of ethanol solution, treated with ultrasound for 30 minutes, and then kept warm for reaction at 80°C-135°C for 20 minutes.

[0020] The above is used for Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres, modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres are specifically amine-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2-NH2 nanospheres, with a diameter of 8nm.

[0021] For Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5Fe 0.5 The application of O2 nanospheres is to modify the above-mentioned modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres—amino nitrogen doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2-NH2 nanospheres are used to prepare photoelectrochemical aptamer sensors, specifically for the detection of Cr 3+ Photoelectrochemical sensor.

[0022] Preferably, detection of Cr 3+ Application of Aminated Nitrogen Doped Praseodymium Iron Oxide N-Pr 0.5 Fe 0.5 The O2-NH2 is used to prepare the working electrode of the photoelectrochemical sensor, including the following specific steps:

[0023] (1) Take 5-20 mg of amine nitrogen doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The O2-NH2 nanospheres were dispersed in 50-200 mL of distilled water and ultrasonically dispersed to form a dispersion;

[0024] Take 6-20 μL of the dispersion to modify the ITO electrode and dry it at room temperature to form a film to form ITO / N-Pr 0.5 Fe 0.5 O2-NH2 electrode;

[0025] (2) 1-10 μL, 2.5% glutaraldehyde solution and 1-5 μg / mL specific recognition Cr were added dropwise respectively. 3+ The aptamer chain DNA1 forms ITO / N-Pr 0.5 Fe 0.5 O2-NH2 / DNA1 electrode;

[0026] (3) Then add 5-20 μL and 0.1 fg mL -1 ~10ng·mL -1 A series of different concentrations of Cr 3+ Solution, rinse with ultrapure water to obtain Cr 3+ Photoelectrochemical aptasensor ITO / N-Pr 0.5 Fe 0.5 O2-NH2 / DNA1-ITO / N-Pr 0.5 Fe 0.5 O2-NH2 / DNA1 / Cr 3+ .

[0027] Preferably, the specific detection method steps are as follows:

[0028] (1) The test was carried out using an electrochemical workstation with a three-electrode system, a saturated calomel electrode as the reference electrode, and a graphite electrode as the auxiliary electrode. 3+ The photoelectrochemical aptamer sensor was used as the working electrode and tested in PBS buffer with a pH adjusted to 5.0-8.0 and a concentration of 0.1 mol / L-1.0 mol / L;

[0029] (2) Using the time-current method to measure Cr 3+ For testing, set the voltage to -0.2V-0.2V, the running time to 30s-80s, and the wavelength of the light source to 400nm-550nm;

[0030] (3) Turn on the light source every 20 seconds and continue irradiating for 20 seconds, record the photocurrent, and draw a working curve.

[0031] The present invention provides a method for Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nano-microspheres and their preparation method and application have the following beneficial effects:

[0032] (1) The present invention prepares the 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres have excellent photoelectrochemical properties. They have a unique molecular structure and an adjustable energy band gap in the field of photoelectrochemistry. As electron acceptors and photogenerated charge transfer media, they can effectively capture photogenerated electrons in semiconductor materials, thereby promoting charge separation and transfer.

[0033] The introduction of nitrogen atoms introduces extra electrons into the material, forming negatively charged nitrogen-doped regions, which enhances the conductivity of the material. Nitrogen doping changes the surface structure and electronic properties of the material, thereby improving its catalytic activity.

[0034] Finally, through the combined effect of nitrogen doping and praseodymium iron oxide, the material of the present invention has excellent photoelectrochemical performance. Under light conditions, it can generate significant photocurrent and photovoltage responses, which is beneficial for application in the field of photoelectrochemistry.

[0035] The multivalent states and catalytic activity of praseodymium and iron also have a positive effect on the catalytic performance, so nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 has remarkable catalytic performance and also exhibits good stability under a variety of conditions.

[0036] (2) The present invention is used for Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr0.5 Fe 0.5 O2 nanospheres are used as photoelectrochemical sensing materials to prepare photoelectrochemical aptamer sensors. They use the principle of photoelectrochemistry to generate current or voltage response through light excitation, which is used as the detection signal, significantly improving the Cr 3+ The accuracy and sensitivity of the detection have the advantages of low cost, high selectivity, high sensitivity and rapid detection.

[0037] Moreover, by utilizing the specific reaction between nucleic acid aptamers and photoelectrochemical sensing materials, the interference of other substances in the detection can be effectively avoided, so that the sensor of the present invention can accurately identify the target substance even in a complex environment, significantly improve the accuracy of detection, have a fast response, and can provide detection results in a short time, thus realizing the detection needs of real-time monitoring and rapid response.

[0038] Compared with the traditional detection method, the present invention realizes the detection of Cr under visible light conditions. 3+ The linear range of trivalent chromium detection is 0.1 fg·mL -1 -10ng·mL -1 , the detection limit is 0.033fg·mL -1 ; and the detection concentration reaches 10 -17 g·mL -1 , while the detection limit of conventional detection methods is usually 10 -5 ~10 -12 g·mL -1 , which is more sensitive. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The N-Pr prepared in Example 1 0.5 Fe 0.5 Transmission electron microscopy image of O2 nanospheres;

[0040] Figure 2 The N-Pr prepared in Example 1 0.5 Fe 0.5 High-angle annular dark-field scanning transmission electron microscopy image of O2 nanospheres;

[0041] Figure 3 The Cr prepared in Example 2 3+ Performance test diagram of photoelectrochemical aptamer sensor;

[0042] Figure 4 In this embodiment 3, the photoelectrochemical aptamer sensor is used to detect Cr 3+ Detection linear range test chart. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0044] Example 1

[0045] Preparation for Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The method of O2 nanospheres comprises the following steps:

[0046] (1) Preparation of praseodymium iron oxide Pr 0.5 Fe 0.5 O2 nanospheres

[0047] 5g of praseodymium chloride, 2g of ferric chloride, and 5g of ammonium chloride were weighed on an electronic balance and prepared into a mixed solution with 500mL of ethylene glycol; 20mg of sodium hexadecylbenzenesulfonate was weighed and added into the mixed solution, and the solution was ultrasonicated for 10min, and then placed in a polytetrafluoroethylene-lined autoclave for reaction at 120℃ for 20h to obtain Pr 0.5 Fe 0.5 O2 nanospheres.

[0048] (2) Preparation of nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres

[0049] Take the praseodymium iron oxide Pr prepared in the above step (1) 0.5 Fe 0.5 2.0 g of O2 nanospheres were placed in the downstream of the tube furnace, 25.0 g of melamine was added to the upstream of the tube furnace, and the upstream of the tube furnace was heated from room temperature to 1200 ° C in a nitrogen atmosphere and kept warm for 60 min; the downstream of the tube furnace was heated from room temperature to 1200 ° C and kept warm for 60 min to obtain nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres.

[0050] (3) Preparation of Aminated Nitrogen Doped Praseodymium Iron Oxide N-Pr 0.5 Fe 0.5 O2-NH2

[0051] Take 10 mg of the nitrogen-doped praseodymium iron oxide N-Pr prepared in step (2) above. 0.5 Fe 0.5O2 nanospheres were dispersed in 100 ml of ethanol solution, and 20 ml of 3-aminopropyltriethoxysilane was added. The mixed solution was ultrasonically treated for 30 min and kept at 80°C-135°C for 20 min. Finally, it was centrifuged, washed and dried to obtain amino-functionalized N-Pr 0.5 Fe 0.5 O2-NH2 nanospheres.

[0052] like Figure 1 and Figure 2 As shown, the nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 has a diameter of 8nm. It has a unique molecular structure and an adjustable energy band gap, and can act as an electron acceptor and a medium for photogenerated charge transfer. It can effectively capture photogenerated electrons in semiconductor materials, thereby promoting charge separation and transfer.

[0053] At the same time, the introduction of nitrogen atoms can change the lattice structure of the original oxide, introduce additional electrons into the material, and form a negatively charged nitrogen-doped region. Nitrogen doping also changes the magnetic properties of praseodymium iron oxide due to the interaction between nitrogen atoms and atoms in the original lattice, thereby enhancing the conductivity of the material. 0.5 Fe 0.5 As a photoelectrochemical sensing material, O2 may have excellent photoelectrochemical performance through the combined effects of nitrogen doping and praseodymium iron oxide. Under light conditions, it can produce significant photocurrent and photovoltage responses, which is conducive to its application in the field of photoelectrochemistry.

[0054] The nitrogen-doped praseodymium iron oxide N-Pr prepared in the present invention 0.5 Fe 0.5 O2 also has excellent catalytic performance. Nitrogen doping can change the surface structure and electronic properties of the material, thereby improving the catalytic activity. In addition, the multivalent states and catalytic activity of praseodymium and iron elements will also have a positive effect on the catalytic performance. 0.5 Fe 0.5 O2 can effectively capture photogenerated electrons in semiconductor materials, thereby promoting charge separation and transfer, which can effectively improve the stability of photoelectric sensors. The stability of the material structure due to nitrogen doping and the high stability of praseodymium iron oxide itself make nitrogen-doped praseodymium iron oxide show good stability under a variety of conditions, and has potential application value in the fields of magnetic materials, optical materials, catalytic materials, etc.

[0055] Example 2

[0056] The nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5O2 nanospheres are used to prepare photoelectrochemical aptamer sensors. The specific preparation steps are as follows:

[0057] (1) 5 mg of N-Pr prepared in Example 1 was added 0.5 Fe 0.5 The O2-NH2 nanospheres were dispersed in 50 mL of distilled water and ultrasonically dispersed for 30 min to form a dispersion;

[0058] Take 6 μL of the above dispersion to modify the ITO electrode and dry it at room temperature to form a film to form ITO / N-Pr 0.5 Fe 0.5 O2-NH2 electrode;

[0059] (2) 5 μL of 2.5% glutaraldehyde solution and 1 μg / mL of specific recognition Cr were added dropwise. 3+ The aptamer chain DNA1 forms ITO / N-Pr 0.5 Fe 0.5 O2-NH2 / DNA1 electrode;

[0060] (3) Add 5 μL of different concentrations, with a concentration of 0.1 fg mL -1 -1-10ng·mL -1 A range of different concentrations of Cr 3+ The solution was washed with ultrapure water to prepare the photoelectrochemical aptamer sensor ITO / N-Pr 0.5 Fe 0.5 O2-NH2 / DNA1-ITO / N-Pr 0.5 Fe 0.5 O2-NH2 / DNA1 / Cr 3+ .

[0061] The room temperature in the embodiments of the present invention is 20-25°C.

[0062] The main components of the photoelectrochemical aptamer sensor prepared in the implementation of the present invention are the photoelectrochemical converter and the aptamer sensor. The function of the photoelectrochemical converter is to convert light energy into electrical energy to provide energy for the entire sensor. The aptamer sensor is a biological molecule with high affinity, which is responsible for specifically identifying and capturing the target substance. When the target substance binds to the aptamer, it will cause the photoelectrochemical signal inside the sensor to change, thereby realizing the detection of the target substance.

[0063] The photoelectrochemical aptamer sensing analysis adopted in the present invention is an analytical method that combines photoelectrochemical technology with the principle of aptamer recognition reaction. The electron-hole pairs generated by the photoelectrochemical sensing material after absorbing energy are used to form a photocurrent or photovoltage through the transfer of electrons. When the aptamer recognition reaction occurs, the electrical signal originally generated by the photoelectric active material will be indirectly or directly changed. By monitoring the changes in these electrical signals, the quantitative determination of the target substance can be achieved.

[0064] like Figure 3 As shown in the figure, the photoelectrochemical aptamer sensor uses the principle of photoelectrochemistry to generate a current or voltage response through light excitation as a detection signal. Since the excitation light source is separated from the detection signal, the background current is low, so the sensor has higher sensitivity. This high sensitivity enables the sensor to detect trace substances, improving the accuracy and reliability of detection. Aptamers are biological molecules with high affinity that can specifically recognize target substances. By screening and optimizing aptamers, specific recognition of target substances can be achieved, thereby avoiding interference with other substances.

[0065] This high selectivity enables the sensor to accurately identify the target substance in a complex environment, improving the accuracy of the detection. In addition, the photoelectrochemical aptamer sensor of the present invention also has a fast response speed. When the target substance binds to the aptamer, it will cause the photoelectrochemical signal inside the sensor to change, and this change can be quickly detected. Therefore, the photoelectrochemical aptamer sensor can provide detection results in a short time, which is conducive to real-time monitoring and rapid response.

[0066] Example 3

[0067] The photoelectrochemical aptamer sensor in Example 2 was applied to Cr 3+ The specific steps for detection are as follows:

[0068] (1) The test was carried out using an electrochemical workstation with a three-electrode system, a saturated calomel electrode as the reference electrode, and a graphite electrode as the auxiliary electrode. 3+ The photoelectrochemical aptamer sensor was used as the working electrode and tested in PBS buffer with a pH of 7.4 and a concentration of 0.5 mol / L;

[0069] (2) Using the time-current method to measure Cr 3+ For testing, set the voltage to -0.1V, the running time to 60s, and the wavelength of the light source to 400nm;

[0070] (3) Turn on the light source every 20 seconds and continue irradiating for 20 seconds, record the photocurrent, and draw a working curve.

[0071] like Figure 4 As shown, the invention is used to construct a Cr3+ Detection of N-Pr 0.5 Fe 0.5 The photoelectrochemical aptamer sensor of O2 nanospheres can sense Cr at low voltage and low content. 3+ The detection range is 0.1fg·mL -1 -10ng·mL -1 , the detection limit is 0.033fg·mL -1 , for Cr 3+ The detection limit can reach 10 -17 g·mL -1 , while the detection limit of conventional detection methods is usually 10 -5 ~10 -12 g·mL -1 .

[0072] Therefore, the photoelectrochemical aptamer sensor of the present invention is more sensitive than the detection method in the prior art. 3+ The detection method is unable to accurately detect low content. The solution of the present invention provides strong technical support for the future detection of heavy metal ions in environmental water bodies.

[0073] In summary, the invention is used for Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres and their preparation method and application, through the synergistic effect of nitrogen doping and praseodymium iron oxide, the material of the invention has excellent photoelectrochemical properties, using the nitrogen doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 Photoelectrochemical aptamer sensor constructed with O2 nanospheres can detect Cr under visible light conditions. 3+ It is a rapid and ultra-sensitive detection method with low cost, high selectivity, high sensitivity and rapid detection, which is conducive to real-time monitoring and rapid response, and can be widely used in magnetic materials, optical materials, catalytic materials and other fields.

[0074] The above are only embodiments of the present invention. For example, the nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres can also be used in the field of magnetism to prepare high-performance magnetic recording materials; in the field of optics, they can be used to prepare photocatalysts, optical sensors, etc.; in the field of catalysis, they can be used as catalyst carriers or active components in catalytic reactions.

[0075] Finally, although this specification is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The method for preparing O2 nanospheres is characterized in that: The steps include: (1) Preparation of praseodymium iron oxide Pr 0.5 Fe 0.5 O2 nanospheres: Weigh a certain mass ratio of praseodymium chloride PrCl, ferric chloride FeCl3, and ammonium chloride NH4Cl, and prepare a mixed solution with ethylene glycol. Add sodium hexadecylbenzene sulfonate to the mixed solution, dissolve it, and place it in a polytetrafluoroethylene-lined high-pressure reactor. React at 120℃-220℃ for 10h-20h to obtain praseodymium iron oxide Pr 0.5 re 0.5 O2 nanospheres; (2) Preparation of nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres: Using the thermal decomposition of melamine to achieve the Pr 0.5 Fe 0.5 The praseodymium iron oxide Pr prepared in step (1) is doped with non-metallic nitrogen on the O2 nanospheres. 0.5 Fe 0.5 O2 nanospheres are placed downstream of the tube furnace, and melamine is placed upstream of the tube furnace. They are heated in a nitrogen atmosphere. The upstream of the tube furnace is heated from room temperature to 600℃-1200℃ for insulation reaction, and the downstream of the tube furnace is heated from room temperature to 1000℃-1200℃ for insulation reaction to obtain nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres.

2. A method for Cr according to claim 1 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 re 0.5 The method for preparing O2 nanospheres is characterized in that: The invention also includes step (3) of preparing amine nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2-NH2: The nitrogen-doped praseodymium iron oxide N-Pr 0. 5Fe 0.5 O2 nanospheres and 3-aminopropyltriethoxysilane were dispersed in an ethanol solution and reacted at 80-135°C for 20-40 min. After centrifugation, washing and drying, amino-functionalized N-Pr 0.5 re 0.5 O2-NH2 nanospheres.

3. A method for Cr according to claim 1 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The method for preparing O2 nanospheres is characterized in that: Step (1) Preparation of praseodymium iron oxide Pr 0.5 Fe 0.5 The specific steps of O2 nanospheres include the following: Weigh praseodymium chloride, ferric chloride and ammonium chloride in a weight ratio of praseodymium chloride: ferric chloride: ammonium chloride = (2.2-10.0) g: (1.0-5.5) g: (2.0-10.0) g, add to 500 ml of ethylene glycol solvent to prepare a mixed solution, add 1.0 mg-100 mg of sodium hexadecylbenzene sulfonate to the mixed solution, and place in a polytetrafluoroethylene-lined autoclave after ultrasonic treatment, and react at 120° C.-220° C. for 10 h-20 h to obtain praseodymium iron oxide Pr 0.5 Fe 0.5 O2 nanospheres.

4. A method for Cr according to claim 1 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The method for preparing O2 nanospheres is characterized in that: Step (2) Preparation of nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 In O2 nanospheres, The praseodymium iron oxide Pr 0. 5Fe 0.5 The ratio of the amount of O2 nanospheres to the amount of melamine added is: (2.0-10.0) g: (10.0-25.0) g; Under nitrogen atmosphere, heat the upstream of the tubular furnace from room temperature to 600°C-1200°C and keep it warm for 15min-60min, and heat the downstream of the tubular furnace from room temperature to 1000°C-1200°C and keep it warm for 60min-120min.

5. A method for Cr according to claim 2 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The method for preparing O2 nanospheres is characterized in that: Step (3) Preparation of Aminated Nitrogen-doped Praseodymium Iron Oxide N-Pr 0.5 Fe 0.5 10 mg of nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The O2 nanospheres were added with 20 ml of 3-aminopropyltriethoxysilane, dispersed in 100 ml of ethanol solution, treated with ultrasound for 30 min, and then kept warm for reaction at 80°C-135°C for 20 min.

6. A method for Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres, characterized in that The method for Cr according to any one of claims 1 to 5 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres are specifically amine-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2-NH2 nanospheres, with a diameter of 8nm.

7. A method for Cr 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The application of O2 nano-microspheres is characterized by: The modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2 nanospheres-amino nitrogen doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 O2-NH2 nanospheres are used to prepare photoelectrochemical aptamer sensors, specifically for the detection of Cr 3+ Photoelectrochemical sensor.

8. A method for Cr according to claim 7. 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The application of O2 nano-microspheres is characterized by: Detection of Cr 3+ Application of Aminated Nitrogen Doped Praseodymium Iron Oxide N-Pr 0.5 Fe 0.5 The O2-NH2 is used to prepare the working electrode of the photoelectrochemical sensor, including the following specific steps: (1) Take 5-20 mg of amine nitrogen doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The O2-NH2 nanospheres were dispersed in 50-200 mL of distilled water and ultrasonically dispersed to form a dispersion; Take 6-20 μL of the dispersion to modify the ITO electrode and dry it at room temperature to form a film to form ITO / N-Pr 0.5 Fe 0.5 O2-NH2 electrode; (2) 1-10 μL, 2.5% glutaraldehyde solution and 1-5 μg / mL specific recognition Cr were added dropwise respectively. 3+ The aptamer chain DNA1 forms ITO / N-Pr 0.5 Fe 0.5 O2-NH2 / DNA1 electrode; (3) Then add 5-20 μL and 0.1 fg.mL dropwise. -1 ~10ng·mL -1 A series of different concentrations of Cr 3+ Solution, rinse with ultrapure water to obtain Cr 3+ Photoelectrochemical aptasensor ITO / N-Pr 0.5 Fe 0.5 O2-NH2 / DNA1_ITO / N-Pr 0.5 Fe 0.5 O2-NH2 / DNA1 / Cr 3+ .

9. A method for Cr according to claim 8 3+ Detection of modified nitrogen-doped praseodymium iron oxide N-Pr 0.5 Fe 0.5 The application of O2 nano-microspheres is characterized by: The specific detection method steps are as follows: (1) The test was carried out using an electrochemical workstation with a three-electrode system, a saturated calomel electrode as the reference electrode, and a graphite electrode as the auxiliary electrode. 3+ The photoelectrochemical aptamer sensor was used as the working electrode and tested in PBS buffer with a pH adjusted to 5.0-8.0 and a concentration of 0.1 mol / L-1.0 mol / L; (2) Using the time-current method to measure Cr 3+ For testing, set the voltage to -0.2V-0.2V, the running time to 30s-80s, and the wavelength of the light source to 400nm-550nm; (3) Turn on the light source every 20 seconds and continue irradiating for 20 seconds, record the photocurrent, and draw a working curve.

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