Ce / Zr double-metal doped UiO-67 material for nitric oxide detection and method and application of Ce / Zr double-metal doped UiO-67 material

Abstract

The invention discloses a Ce / Zr bimetal doped UiO-67 material for nitric oxide detection and a method and application thereof, and belongs to the technical field of functional materials and electrochemical sensing. The preparation method disclosed by the invention comprises the following steps: dissolving 4, 4 '-biphenyldicarboxylic acid in a polar solvent, performing ultrasonic dispersion, adding a mixed solution of cerium salt and zirconium salt, and stirring to obtain a precursor solution; adding a carboxylic acid conditioning agent into the precursor solution, and then carrying out solvothermal reaction to obtain a reaction product; and carrying out post-treatment on the reaction product to obtain the Ce / Zr bimetal doped UiO-67 material for nitric oxide detection. The method solves the problems of insufficient activity and poor stability of the traditional MOF material in electrochemical sensing.

Description

Technical Field

[0001] This invention belongs to the field of functional materials and electrochemical sensing technology, specifically relating to a Ce / Zr bimetallic doped UiO-67 material, method, and application for nitric oxide detection. Background Technology

[0002] Nitric oxide (NO), a crucial gaseous signaling molecule in living organisms, is widely involved in and regulates various core physiological and pathological processes, including cardiovascular function, neurotransmission, immune responses, and apoptosis. Its concentration levels in biological systems (typically in the nanomolar to micromolar range) are closely related to the occurrence, development, and prognosis of many major diseases, such as inflammation, sepsis, cardiovascular disease, neurodegenerative diseases, and cancer. Therefore, developing real-time, highly sensitive, highly selective, and highly stable detection technologies for NO in complex biological environments is of significant scientific value and urgently needed for a deeper understanding of disease mechanisms, the discovery of early diagnostic biomarkers, and the dynamic evaluation of treatment efficacy.

[0003] Currently, the detection of NO mainly relies on spectroscopic and electrochemical methods. Spectroscopic methods, such as chemiluminescence and fluorescent probe methods, typically have high sensitivity, but often require complex sample pretreatment, rely on large, precision instruments, or introduce exogenous labeled molecules, making it difficult to achieve truly real-time, in vivo, and non-intrusive detection, and they are also costly. In contrast, electrochemical methods are simple to operate, have a fast response, are easy to miniaturize and integrate, and are suitable for continuous monitoring, making them the most promising in vivo NO detection methods. The core of these methods lies in the electrocatalytic material modified on the surface of the working electrode, which directly determines the sensor's performance.

[0004] Metal-organic frameworks (MOFs) have shown great potential in the field of electrochemical sensing due to their ultra-high specific surface area, tunable pore structure, and abundant designable active sites. Among them, the UiO-67 series MOFs have attracted much attention due to their excellent structural stability in aqueous and electrochemical environments. Previous studies have attempted to introduce the redox-active element Ce into the MOF framework (such as Ce-UiO-67), utilizing Ce... 3+ / Ce 4+The catalytic activity of redox couples is used to detect H2O2 or gas molecules. In addition, research has explored the construction of bimetallic MOFs, aiming to enhance specific catalytic performance through synergistic effects between metals. Monometallic MOFs, represented by Ce-UiO-67, have single catalytic active sites, limited adsorption capacity for polar NO molecules, and generally poor conductivity, resulting in sensor sensitivity, response speed, and stability that fail to meet the requirements for detecting complex biological samples. Existing bimetallic MOF research has largely focused on combining metals with similar catalytic activities, or has failed to precisely design the functional division and synergistic mechanisms between metals. For the specific detection pathway of NO molecules—"adsorption followed by catalytic oxidation"—there is a lack of a directional material design strategy that can simultaneously enhance adsorption and accelerate electron transfer. Summary of the Invention

[0005] The purpose of this invention is to provide a Ce / Zr bimetallic doped UiO-67 material, method, and application for nitric oxide detection, in order to solve the technical problems of insufficient sensitivity, limited selectivity, and poor long-term stability in the electrochemical detection of the biolabeled molecule NO in the prior art.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection, comprising the following steps: 4,4'-biphenyl dicarboxylic acid was dissolved in a polar solvent, ultrasonically dispersed, and then a mixed solution of cerium salt and zirconium salt was added. After stirring, a precursor solution was obtained. A carboxylic acid modifier is added to the precursor solution, followed by a solvothermal reaction to obtain the reaction product; After post-processing the reaction products, Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection was obtained.

[0007] Furthermore, the carboxylic acid modifier is glacial acetic acid; The polar solvent is N,N-dimethylformamide; the cerium salt is cerium ammonium nitrate; and the zirconium salt is zirconium oxynitrate.

[0008] Furthermore, the mixed solution of cerium salt and zirconium salt is obtained by mixing cerium salt and zirconium salt in deionized water; In the mixed solution of cerium salt and zirconium salt, the molar ratio of cerium to zirconium is 1:4 to 4:1; the concentration of the mixed solution of cerium salt and zirconium salt is 0.3 to 0.6 M.

[0009] Furthermore, the ratio of 4,4'-biphenyl dicarboxylic acid to polar solvent is 0.5~1g:20~30mL.

[0010] Furthermore, the ratio of the volume of the mixed solution of 4,4'-biphenyldicarboxylic acid and cerium salt to zirconium salt is 0.5~1g:10~20mL.

[0011] Furthermore, the ratio of the precursor solution to the carboxylic acid modifier is 20-30 mL: 1-2 mL.

[0012] Furthermore, the temperature of the solvothermal reaction is 80~120℃, the time is 15~30min, and the condition of the solvothermal reaction is an oil bath.

[0013] Furthermore, the post-processing includes sequential centrifugation, washing, and vacuum drying. The washing process involves sequentially washing with DMSO, DMF, and anhydrous ethanol. The vacuum drying temperature is 65~75℃.

[0014] The present invention also discloses a Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection prepared by the above method, wherein the Ce / Zr bimetallic doped UiO-67 material has a porous crystal structure.

[0015] The present invention also discloses the application of the Ce / Zr bimetallic doped UiO-67 material nitric oxide electrochemical sensor for nitric oxide detection. The sensor has a detection limit of less than 50 nM for nitric oxide, a linear detection range of 280 nM to 127 μM, and a current response retention rate of more than 87% after four weeks of continuous operation.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection. This method combines the synergistic catalytic advantages of Ce / Zr bimetals, the structural stability of the UiO-67 framework, and the morphological controllability of glacial acetic acid modulation, forming a novel material preparation method for highly sensitive and selective electrochemical sensing of nitric oxide. The glacial acetic acid-assisted solvothermal synthesis is a mild yet efficient material preparation strategy, playing a crucial role in achieving uniform metal ion doping and precise control of the framework structure. It can construct bimetallic nodes with abundant active sites in situ, giving the material excellent intrinsic electrocatalytic activity. The synergistic effect of the Ce / Zr bimetallic nodes provides an efficient reaction interface for the adsorption and oxidation of NO. The strongly Lewis acidic Zr sites effectively enrich NO molecules, while the reversible Ce... 3+ / Ce 4 +Redox couples efficiently catalyze electron transfer processes, significantly enhancing sensing performance. The introduction of acetic acid modulator further optimizes crystal growth, increases the specific surface area of ​​the material, and promotes the exposure of active sites, thereby solving the problems of insufficient activity and poor stability of traditional MOF materials in electrochemical sensing.

[0017] Furthermore, this method synthesizes the target material in one step, avoiding complex post-modification or composite steps, simplifying the process flow. The material properties can be precisely controlled by adjusting the metal ratio and the amount of acetic acid, exhibiting good reproducibility and suitability for large-scale preparation. In addition, the material prepared by this method possesses excellent chemical and mechanical stability, and can be directly used to construct durable electrochemical sensors, providing a reliable material basis for in vivo, real-time NO detection.

[0018] The present invention also discloses a Ce / Zr bimetallic doped UiO-67 material prepared by the above preparation method. This material has a highly ordered porous crystal structure and a uniform pore size distribution, providing an ideal channel for efficient mass transfer and adsorption of reactant molecules. Attached Figure Description

[0019] Figure 1 This is a diagram illustrating the electrochemical sensing mechanism of the Ce / Zr bimetallic doped UiO-67 material prepared for nitric oxide detection according to the present invention. Figure 2 This is a diagram illustrating the synthesis and structural design of the Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection according to the present invention. Figure 3 SEM images and particle size distributions of samples prepared by different methods in this invention; Where: a - Low-magnification and high-magnification SEM images and particle size distribution maps of Comparative Example 1; b - Low-magnification and high-magnification SEM images and particle size distribution of Comparative Example 2; c-Low-magnification and high-magnification SEM images and particle size distribution maps of Example 1; Figure 4 XRD patterns of samples prepared by different methods Figure 5 The N2 adsorption-desorption curves and pore size distributions of samples prepared by different methods are shown. Wherein: a-N2 adsorption-desorption curve; b-pore size distribution diagram; Figure 6 Electrochemical performance testing of samples prepared by different methods in this invention; Wherein: (a) - Cyclic voltammetric current response; (b) - Impedance plot; (c) and (d) Selectivity test of Example 3; (e) - Nitric oxide linear response of Example 3.

[0020] Figure 7 The results of response kinetics testing and long-term stability testing of the sample prepared in Example 3 of this invention; Wherein: (a) - response dynamics test; (b) - long-term stability test. Detailed Implementation

[0021] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0022] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0023] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0024] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0025] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0026] The aim is to achieve a precise "adsorption-catalysis" bifunctional design: introducing strongly Lewis acidic Zr sites to specifically enhance NO adsorption, while utilizing reversible Ce... 3+ / Ce 4+ A redox couple was used to efficiently catalyze the oxidation of NO, and the material structure was optimized by combining it with an acetic acid-assisted morphology control strategy. This resulted in the preparation of a NO electrochemical sensing material with ultra-high sensitivity, excellent selectivity, and outstanding stability, aiming to advance the development of highly reliable in vivo NO detection technologies. Figure 1 As shown.

[0027] This invention provides a method for preparing Ce / Zr bimetallic doped UiO-67 material for highly sensitive electrochemical sensing of nitric oxide, comprising the following steps: Step 1: Preparation of precursor solution: Dissolve the organic ligand 4,4'-biphenyl dicarboxylic acid in a polar solvent, disperse it by ultrasonication, and then add a mixed solution of cerium salt and zirconium salt, wherein the molar ratio of cerium to zirconium is 1:4 to 4:1. Stir at room temperature to form a homogeneous precursor solution. Step 2: Transfer the obtained precursor solution to a reaction vessel, add glacial acetic acid as a carboxylic acid modifier, react at 100°C for 15 minutes, and cool to room temperature after the reaction is complete. Step 3: The solid product obtained in the previous step was centrifuged and washed successively with dimethyl sulfoxide (DMSO), dimethylformamide (DMF) and anhydrous ethanol, and then dried under vacuum at 70°C to obtain Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection.

[0028] Preferably, in step 1, the molar ratio of Ce to Zr in the material is 1:4 to 4:1; more preferably, the molar ratio of cerium to zirconium is 3:2.

[0029] Preferably, in step 2, the amount of glacial acetic acid added is 1 mL.

[0030] Specifically, the above preparation method is as follows: Step 1: Preparation of precursor solution 0.5 g of the organic ligand 4,4'-biphenyl dicarboxylic acid was dissolved in the polar solvent DMF and ultrasonically dispersed. 10 mL of a 0.533 M mixed solution of cerium and zirconium salts was added to the solution, wherein the ratio of cerium to zirconium ions was 1:4, 2:3, 3:2, or 4:1. The solution was stirred at room temperature to obtain a homogeneous precursor solution. Step 2: Solvent-thermal reaction synthesis The precursor solution obtained in the first step was transferred to a reaction flask, and 0-2 mL of glacial acetic acid was added. Then, a solvothermal reaction was carried out at 100°C for 15 minutes. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. Step 3: Product Post-processing The solid product obtained from the reaction was separated by centrifugation at a speed of 4000 rpm for 2 minutes; and washed 1, 1, and 3 times with DMSO, DMF, and anhydrous ethanol, respectively; finally, it was vacuum dried at 70°C for 12 hours to obtain Ce / Zr bimetallic doped UiO-67 material powder for nitric oxide detection. Step 4: Material property characterization and application The Ce / Zr bimetallic doped UiO-67 material obtained in the third step for nitric oxide detection was mixed with carbon black at a 1:1 ratio to form a conductive paste, which was then coated onto the surface of a glassy carbon electrode to prepare an electrochemical sensing electrode. The detection limit for nitric oxide in phosphate buffer was less than 50 nM, the linear detection range covered 280 nM to 127 μM, and it exhibited high selectivity for common biological interfering substances such as ascorbic acid and uric acid. After four weeks of continuous operation, the current response retention rate was above 87%.

[0031] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0032] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0033] Example 1 A method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection includes the following steps: 0.5 g of 4,4'-biphenyl dicarboxylic acid was ultrasonically dispersed in 30 mL of DMF for 30 min. Under continuous stirring, 6 mL of 0.533 M cerium ammonium nitrate and 4 mL of 0.533 M zirconium oxynitrate solution were added dropwise to the mixture. After stirring for 5 min, 1 mL of glacial acetic acid was added dropwise to the mixture. The reaction system was then heated in an oil bath at 100 ℃ for 15 min. The resulting yellow precipitate was collected and washed once with DMSO, once with DMF, and three times with ethanol. The final product was dried in an oven at 70 ℃ for 12 h to obtain Ce / Zr bimetallic doped UiO-67 material (H1-Ce3Zr2-UiO-67) for nitric oxide detection.

[0034] Example 2 A method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection includes the following steps: 1 g of 4,4'-biphenyl dicarboxylic acid was ultrasonically dispersed in 20 mL of DMF for 30 min. Under continuous stirring, 10 mL of 0.533 M cerium ammonium nitrate and 10 mL of 0.533 M zirconium oxynitrate solution were added dropwise to the mixture. After stirring for 5 min, 2 mL of glacial acetic acid was added dropwise to the mixture. The reaction system was then heated in an oil bath at 80 ℃ for 30 min. The resulting yellow precipitate was collected and washed once with DMSO, once with DMF, and three times with ethanol. The final product was dried in an oven at 65 ℃ for 12 h to obtain Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection.

[0035] Comparative Example 1 A method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection includes the following steps: 0.5 g of 4,4'-biphenyl dicarboxylic acid was ultrasonically dispersed in 30 mL of DMF for 30 min. Under continuous stirring, 10 mL of 0.533 M cerium ammonium nitrate solution was added dropwise to the mixture. The reaction system was then heated in an oil bath at 100 ℃ for 15 min. The resulting yellow precipitate was collected and washed once with DMSO, once with DMF, and three times with ethanol. The final product was dried in an oven at 70 ℃ for 12 h to obtain Ce / Zr bimetallic doped UiO-67 material (Ce-UiO-67) for nitric oxide detection.

[0036] The Ce-UiO-67 has a particle size of 667 nm. Ce-UiO-67 and carbon black were mixed in a 1:1 ratio to prepare a 5 mg / mL conductive slurry, which was ultrasonically dispersed for 30 min. 5 μL of the slurry was then uniformly coated onto the surface of a glassy carbon electrode, and its NO sensing characteristics were tested in a deoxygenated phosphate solution. Figure 6 As shown in Example 1, the oxidation current at 0.85 V is 13.1 μA and the impedance is 98.77 Ω.

[0037] Comparative Example 2 A method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection includes the following steps: 0.5 g of 4,4'-biphenyl dicarboxylic acid was ultrasonically dispersed in 30 mL of DMF for 30 min. Under continuous stirring, 6 mL of 0.533 M cerium ammonium nitrate and 4 mL of 0.533 M zirconium oxynitrate solution were added dropwise to the mixture. The reaction system was then heated in an oil bath at 100 ℃ for 15 min. The resulting yellow precipitate was collected and washed once with DMSO, once with DMF, and three times with ethanol. The final product was dried in an oven at 70 ℃ for 12 h to obtain Ce / Zr bimetallic doped UiO-67 material (Ce3Zr2-UiO-67) for nitric oxide detection.

[0038] The particle size of the Ce3Zr2-UiO-67 is Figure 3 The measured NO sensing wavelength was 449 nm. Ce3Zr2-UiO-67 and carbon black were mixed in a 1:1 ratio to prepare a 5 mg / mL conductive slurry. This slurry was ultrasonically dispersed for 30 min. 5 μL of the slurry was then uniformly coated onto the surface of a glassy carbon electrode, and its NO sensing characteristics were tested in a deoxygenated phosphate solution. (Example: ...) Figure 6 As shown in Example 2, the oxidation current at 0.85 V is 24.2 μA and the impedance is 87.18 Ω. Compared with Example 1, the introduction of Zr in Example 2 increases the oxidation current and reduces the impedance, resulting in better overall sensing characteristics for NO.

[0039] The particle size of H1-Ce3Zr2-UiO-67 is Figure 1 The measured 449 nm; H1-Ce3Zr2-UiO-67 and carbon black were mixed in a 1:1 ratio to prepare a 5 mg / mL conductive slurry, which was ultrasonically dispersed for 30 min. 5 μL of the slurry was then uniformly coated onto a glassy carbon electrode, and the NO sensing characteristics were tested in a deoxygenated phosphate solution. (Example: ...) Figure 6 As demonstrated, Example 1 showed an oxidation current of 35.1 μA and an impedance of 84.3 Ω at 0.85 V. Compared to Comparative Examples 1 and 2, the acetic acid-controlled sample in Example 1 showed a significant increase in oxidation current and a significant decrease in impedance. Figure 6 c and d show that the sample has a specific response only to NO, and the current response to other interfering substances is negligible. Figure 6 e indicates that there is a linear relationship between the detection current and concentration of NO in the sample. Figure 5 Example 1 shows a rapid response to NO within 1.4 s. Figure 7 b indicates that Example 1 retains 87% of its oxidation current after 28 days. Based on various characterizations, Example 1 demonstrates high sensitivity, high selectivity, low detection limit, and repeatability in NO sensing.

[0040] Figure 1This diagram illustrates the electrochemical sensing mechanism of the Ce / Zr bimetallic doped UiO-67 material prepared for nitric oxide detection according to the present invention. During oxidation, NO molecules diffuse from the solution to the surface of the Ce / Zr bimetallic doped UiO-67 material, where their lone pair electrons interact with the strongly Lewis acidic sites of Zr. 4+ The interaction between the materials enables efficient physical adsorption. The high specific surface area and uniformly distributed Zr sites ensure excellent NO capture efficiency. Meanwhile, Ce... 4+ As an electron acceptor, the oxidation of NO generates a detectable current-sensing signal through electron transfer. Zr 4+ The induced stronger adsorption can significantly increase the local NO concentration around the active Ce sites, thereby greatly accelerating electron transfer kinetics and overall reaction efficiency, ultimately achieving high sensitivity and rapid response. The generated NO... + It hydrolyzes with water molecules to form nitrous acid (HNO2), which then further dissociates. Simultaneously, Ce is generated... 3+ Electrochemical oxidation to Ce at the electrode interface 4+ This completes the sensing cycle, thereby maintaining Ce. 3+ / Ce 4+ Dynamic equilibrium of redox couples.

[0041] Figure 2 This diagram shows the synthesis process and structural design of the Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection prepared in this invention.

[0042] Figure 3 SEM images and particle size distribution diagrams of Comparative Example 1, Comparative Example 2, and Example 1 are shown. Figure 3 As shown in Figure a, Comparative Example 1 exhibits an irregular blocky morphology with an average particle size of approximately 660 nm. In contrast, after introducing Zr into the framework, the particle size of Comparative Example 2 was significantly reduced ( Figure 3 (b) This is attributed to the introduction of dissimilar Zr nodes, which accelerates nucleation and inhibits grain growth. Furthermore, the addition of acetic acid as a modulator has a more significant impact on the grain size of the bimetallic MOF system. Figure 3 As shown in c, compared with the unmodulated Comparative Example 2, the average particle size of Comparative Example 1 is significantly reduced to about 41 nm.

[0043] Figure 4 The XRD patterns of Comparative Example 1, Comparative Example 2, and Example 1 are shown. All samples exhibit a sharp diffraction peak at 5.8°, which is consistent with the simulated spectrum of UiO-67. Figure 1 The successful construction of the target MOF framework was confirmed. Due to the reduced grain size (as confirmed by SEM images), the XRD diffraction peaks of Example 1 were significantly broadened.

[0044] Figure 5The N2 adsorption-desorption curves and pore size distributions of Comparative Example 1, Comparative Example 2, and Example 1 are shown. The BET specific surface area of ​​Comparative Example 1 is 68.08 m² / g, while that of Comparative Example 2 is significantly increased to 312.52 m² / g. 2 / g, while the specific surface area of ​​Example 1 was further increased to 522.11 m². 2 / g. This increase helps enhance NO adsorption capacity, thereby improving its NO sensing performance. All three materials exhibit a narrow pore size distribution centered at 1.1 nm. Clearly, the pore size of the synthesized sample is significantly larger than the NO molecule size (0.34 nm), but significantly smaller than the size of large protein molecules such as hemoglobin and immunoglobulins in the physiological environment (approximately 5 nm). This size difference facilitates the efficient diffusion of NO molecules within the MOF channels while simultaneously blocking the entry of large protein molecules.

[0045] like Figure 6 As shown in Figure a, after adding 100 μM NO, all three materials exhibited a significant oxidation peak around 0.85 V (relative to Ag / AgCl). Example 1 showed the highest peak current response (33.3 μA), approximately 1.38 times that of Comparative Example 2 (24.2 μA) and 2.54 times that of Comparative Example 1 (13.1 μA), indicating that it possessed the optimal electrocatalytic oxidation activity for NO. Electrochemical impedance spectroscopy (EIS) showed that Example 1 had the lowest interfacial charge transfer resistance (Rct = 74.98 Ω), lower than Comparative Example 2 (87.18 Ω) and Comparative Example 1 (98.77 Ω). Figure 6 b). The smallest Rct value indicates a significantly enhanced electron transfer kinetics and superior electrocatalytic activity. This application also evaluated the selectivity of Example 1 for NO in a complex system. Figure 6 As shown in cd, this material reacts with glucose (GLU) and nitrite (NO2). - ), nitrate (NO3) - The responses to physiologically relevant interfering substances such as uric acid (UA) and ascorbic acid (AA) were negligible. Their selectivity coefficients (interfering substance response / NO response) were only 1.51%, 1.99%, 0.24%, 6.48%, and 0.04%, respectively. Even after introducing the interfering substance and then adding NO again, Example 1 still maintained 97% of the current response, confirming its high specificity for NO recognition. The NO sensing performance of Example 1 was further evaluated in 0.1 M PBS using the chronoamperometry (It curve). Figure 6 e). The sensor exhibits a rapid current rise after each NO injection. For example... Figure 6As shown in the inset, its linear detection range is 280 nM to 127 μM, the regression equation is I(μA) = 0.1597C(μM) + 1.5397, and the normalized sensitivity is 2.26 μA·μM. -1 ·cm -2 According to the formula LOD = 3S / K (where S is the standard deviation of the blank signal and K is the slope of the calibration curve), the detection limit is calculated to be 32 nM.

[0046] Response dynamics test ( Figure 7 a) shows that Example 3 can reach 95% of the steady-state current within 1.4 seconds, meeting the key requirement for real-time detection of NO molecules with a half-life of only 3-6 seconds, and also providing the possibility for dynamic real-time monitoring of NO in biological systems. Furthermore, the sensor can still maintain 87% of its initial current response after four weeks of continuous operation. Figure 7 (b) demonstrates excellent long-term operational stability and practical application potential.

[0047] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection, characterized in that, Includes the following steps: 4,4'-biphenyl dicarboxylic acid was dissolved in a polar solvent, ultrasonically dispersed, and then a mixed solution of cerium salt and zirconium salt was added. After stirring, a precursor solution was obtained. A carboxylic acid modifier is added to the precursor solution, followed by a solvothermal reaction to obtain the reaction product; After post-processing the reaction products, Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection was obtained.

2. The method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection according to claim 1, characterized in that, The carboxylic acid modifier is glacial acetic acid; The polar solvent is N,N-dimethylformamide; the cerium salt is cerium ammonium nitrate; and the zirconium salt is zirconium oxynitrate.

3. The method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection according to claim 1, characterized in that, The cerium salt and zirconium salt mixed solution is obtained by mixing cerium salt and zirconium salt in deionized water; In the mixed solution of cerium salt and zirconium salt, the molar ratio of cerium to zirconium is 1:4 to 4:1; the concentration of the mixed solution of cerium salt and zirconium salt is 0.3 to 0.6 M.

4. The method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection according to claim 1, characterized in that, The ratio of 4,4'-biphenyl dicarboxylic acid to polar solvent is 0.5~1g:20~30mL.

5. The method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection according to claim 1, characterized in that, The ratio of the amount of 4,4'-biphenyl dicarboxylic acid and the cerium salt to the zirconium salt in the mixed solution is 0.5~1g:10~20mL.

6. The method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection according to claim 1, characterized in that, The ratio of the precursor solution to the carboxylic acid modifier is 20-30 mL: 1-2 mL.

7. The method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection according to claim 1, characterized in that, The solvothermal reaction is carried out at a temperature of 80~120℃ for a time of 15~30 min, and the solvothermal reaction is carried out in an oil bath.

8. The method for preparing Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection according to claim 1, characterized in that, The post-processing includes sequential centrifugation, washing, and vacuum drying. The washing process involves sequentially washing with DMSO, DMF, and anhydrous ethanol. The vacuum drying temperature is 65~75℃.

9. A Ce / Zr bimetallic doped UiO-67 material for nitric oxide detection, characterized in that, The material is prepared by any one of claims 1 to 8, characterized in that the Ce / Zr bimetallic doped UiO-67 material has a porous crystal structure.

10. The application of the Ce / Zr bimetallic doped UiO-67 material nitric oxide electrochemical sensor for nitric oxide detection as described in claim 9, characterized in that, The sensor has a detection limit of less than 50 nM for nitric oxide, a linear detection range of 280 nM to 127 μM, and a current response retention rate of over 87% after four weeks of continuous operation.

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