Electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofiber and preparation method and application thereof

Abstract

This invention discloses an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, its preparation method, and its application. The preparation method includes... x Ti3C2 nanosheet dispersions were prepared by preparing a Ti3C2 nanosheet dispersion. Zirconium salt, trimesic acid, formic acid, and polyacrylonitrile were added sequentially to obtain an electrospinning precursor solution. Electrospinning yielded a composite nanofiber membrane loaded with MOF-808 precursor and Ti3C2 nanosheets. After pre-oxidation and carbonization, MOF-808 / titanium carbide composite carbon nanofiber powder was obtained. This dispersion was drop-coated onto an electrode surface to construct a three-electrode system, resulting in the target electrochemical sensor. The electrochemical sensor of this invention possesses advantages such as high electron conduction efficiency, high specific enrichment capacity, high electrocatalytic activity, and high stability, enabling highly sensitive, selective, rapid, and stable quantitative detection of chloramphenicol in complex scenarios.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical sensor technology, and relates to an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, its preparation method and application. Background Technology

[0002] Chloramphenicol (CAP) is a broad-spectrum antibiotic that was once widely used in animal husbandry and aquaculture. However, given its potential impact on the human blood system and the risk of antibiotic resistance from environmental microorganisms, my country and many other countries in Europe and America have explicitly banned the detection of chloramphenicol in animal-derived foods.

[0003] Currently, standard methods for detecting chloramphenicol include high-performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS / MS). While these methods offer high accuracy, they suffer from drawbacks such as expensive equipment, cumbersome sample pretreatment, long detection cycles, and inability to perform rapid on-site detection, making them unsuitable for on-site food safety supervision and emergency monitoring of environmental water bodies. Electrochemical sensors, with their advantages of ease of operation, rapid response, low cost, high sensitivity, and miniaturization for on-site detection, have become a core research direction in the field of rapid chloramphenicol detection.

[0004] Currently, studies have reported the use of various nanomaterials (such as traditional carbon materials, metal oxides, or metal-organic frameworks (MOFs)) to modify electrodes for the electrochemical detection of chloramphenicol. However, existing sensing materials still face some common technical bottlenecks in practical applications: on the one hand, single sensing materials often struggle to balance high conductivity and high catalytic activity. For example, conventional MOF materials with high porosity and abundant active sites are mostly intrinsic semiconductors with extremely poor inherent conductivity, leading to hindered electron transport and weak response signals. On the other hand, traditional powdered sensing materials, when modified onto the working electrode surface, often face problems such as easy aggregation, weak interfacial bonding, and poor long-term cycling and mechanical stability. This results in the modified electrode being prone to the shedding or passivation of active substances in complex electrolyte environments, making it difficult to achieve low detection limits and high reproducibility. Therefore, how to design and construct novel composite sensing interface materials that combine excellent electron transport networks, abundant specific catalytic sites, and high structural stability to achieve ultrasensitive and highly stable detection of chloramphenicol is a pressing technical challenge in the field of electrochemical sensing.

[0005] To address the aforementioned technical challenges, current research has attempted to physically composite conductive carbon materials (such as carbon nanotubes and graphene) or metal nanoparticles with MOF materials to improve the conductivity and catalytic activity of the sensing interface. However, a comprehensive analysis of existing chloramphenicol electrochemical sensors and their interface material construction schemes reveals the following common technical bottlenecks: (1) The composite material method leads to low efficiency of functional synergy. The construction of existing composite materials mostly adopts multi-step physical mixing or non-in-situ growth strategies. The functional components rely only on weak van der Waals forces or hydrogen bonds to achieve physical contact, and fail to form a continuous chemical bonding interface. This discontinuous physical contact cannot build an efficient electron transfer channel, and the high interface resistance defect of semiconductor materials such as MOF cannot be fundamentally compensated, resulting in limited improvement of the electrocatalytic response signal of chloramphenicol.

[0006] (2) Lack of spatial confinement effect and low utilization of active sites. In existing physical mixing systems, nanoscale MOF particles lack effective spatial confinement and are prone to irreversible aggregation; at the same time, two-dimensional sheet materials with high specific surface area also undergo severe self-stacking due to interlayer van der Waals forces. The above problems directly lead to a significant reduction in the actual electrochemical active area of ​​the composite material, and a large number of specific enrichment and catalytic sites are masked, which seriously restricts the detection sensitivity and linear range of the sensor.

[0007] (3) Insufficient structural and electrochemical stability of the sensing interface. The existing composite system lacks strong chemical bond anchoring between the components. In complex electrolyte environments and during long-term potential cycling scans, the sensing layer is prone to microstructural disintegration and phase separation. The active material is detached and lost from the electrode surface, resulting in continuous attenuation of the detection signal, which is difficult to meet the requirements of long-term stability for routine monitoring of actual samples.

[0008] (4) The specific recognition and catalytic efficiency of chloramphenicol molecules need to be improved. Existing schemes focus on the simple superposition of conductivity and porosity, and fail to conduct integrated synergistic design of "enrichment-transport-catalysis" functional units based on the molecular structural characteristics and electrochemical reduction mechanism of chloramphenicol. This results in low mass transfer efficiency between enrichment sites and catalytic sites of the target molecule, and coexisting interfering substances in complex matrices are prone to competitive adsorption at non-specific sites, affecting the selectivity and detection accuracy of the sensor.

[0009] (5) The preparation process is cumbersome and not conducive to large-scale production. Existing composite materials usually require independent synthesis of multiple functional components, multi-step mixing and dispersion, and multiple rounds of washing and purification. The preparation process is lengthy, the process error tolerance is low, and it is difficult to ensure the material uniformity between batches. At the same time, sensor modification mostly relies on manual drop-coating to form films, and the film thickness and uniformity are uncontrollable, which further aggravates the batch differences in sensor performance and seriously restricts its transformation from laboratory research to actual industrial application.

[0010] In summary, existing chloramphenicol electrochemical sensing interface materials generally suffer from core bottlenecks such as low electron conduction efficiency, insufficient utilization of active sites, poor structural stability, insufficient specific recognition ability, and complex preparation processes, making it difficult to simultaneously meet the practical requirements of ultra-trace detection for sensitivity, selectivity, stability, and large-scale preparation. Therefore, developing a novel composite sensing interface material that can combine an efficient electron transport network, abundant catalytic active sites, and excellent structural stability has urgent research significance and application value. Summary of the Invention

[0011] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art, especially the problems of low sensitivity, high detection limit, narrow linear range, weak anti-interference ability, poor stability and difficulty in large-scale preparation process of existing chloramphenicol electrochemical sensors. The invention provides an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, which has high electron conduction efficiency, high specific enrichment ability, high electrocatalytic activity and high stability, as well as its preparation method and application, so as to realize highly sensitive, highly selective, rapid and stable quantitative detection of chloramphenicol in complex scenarios such as food, environment and biological matrix.

[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0013] A method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers includes the following steps: (1) Ti3C2T x The nanosheets were added to N,N-dimethylformamide and dispersed by ultrasonication to obtain a Ti3C2 nanosheet dispersion; (2) Zirconium salt, pyromellitic acid, formic acid and polyacrylonitrile were added sequentially to the Ti3C2 nanosheet dispersion obtained above and stirred at room temperature to dissolve, so as to obtain an electrospinning precursor solution. The electrospinning precursor solution was electrospinned with a spinning voltage of 10kV to 20kV, a feed rate of 0.5mL / h to 2mL / h, and a receiving distance of 10cm to 20cm. After electrospinning, the solution was dried to obtain a composite nanofiber membrane loaded with MOF-808 precursor and Ti3C2 nanosheets. (3) The composite nanofiber film loaded with MOF-808 precursor and Ti3C2 nanosheets obtained above is first heated to 200℃~300℃ for pre-oxidation treatment under nitrogen atmosphere, and then heated to 600℃~900℃ for carbonization treatment to achieve MOF-808 crystallization, polyacrylonitrile carbonization and interface coupling. After cooling and grinding, MOF-808 / titanium carbide composite carbon nanofiber powder is obtained. (4) The above-obtained MOF-808 / titanium carbide composite carbon nanofiber powder is added to a solvent and ultrasonically dispersed to obtain a dispersion of MOF-808 / titanium carbide composite carbon nanofiber. The dispersion is then drop-coated onto the surface of a pretreated glassy carbon electrode and dried to obtain a modified electrode based on MOF-808 / titanium carbide composite carbon nanofiber. (5) Using the modified electrode based on MOF-808 / titanium carbide composite carbon nanofiber as the working electrode, the platinum wire electrode as the counter electrode, and Ag / AgCl as the reference electrode, a three-electrode working system is constructed to obtain an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofiber.

[0014] In the above-mentioned method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, preferably, in step (2), the molar ratio of zirconium salt to trimesic acid is 2-4:1, the molar volume ratio of trimesic acid to Ti3C2 nanosheet dispersion is 0.025mmol-0.052mmol:1mL, the volume of formic acid is 5%-20% of the volume of Ti3C2 nanosheet dispersion, and the mass-volume ratio of polyacrylonitrile to Ti3C2 nanosheet dispersion is 0.1g-0.5g:1mL; the zirconium salt is zirconium oxynitrate hydrate or zirconium oxychloride octahydrate.

[0015] In the above-mentioned method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, preferably, in step (3), the heating rate of the pre-oxidation treatment is 1℃ / min to 3℃ / min, the pre-oxidation treatment time is 1h to 3h, the heating rate of the carbonization treatment is 2℃ / min to 5℃ / min, the carbonization treatment time is 1h to 3h, and the MOF-808 is crystallized to obtain MOF-808 nanocrystals, the particle size of the MOF-808 nanocrystals is 20nm to 100nm.

[0016] In the above-mentioned method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, preferably, in step (2), the drying temperature is 60℃~80℃, the drying time is 12h~16h, the fiber diameter of the composite nanofiber membrane loaded with MOF-808 precursor and Ti3C2 nanosheets is 200nm~800nm, and the thickness of the composite nanofiber membrane loaded with MOF-808 precursor and Ti3C2 nanosheets is 1μm~10μm.

[0017] In the above-mentioned method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, preferably, in step (4), the mass-volume ratio of the MOF-808 / titanium carbide composite carbon nanofiber powder to the solvent is 2mg~4mg∶1mL, the solvent is water, and the ultrasonic dispersion time is 15min~30min.

[0018] In the above-mentioned method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, preferably, in step (4), the pretreatment process of the glassy carbon electrode surface is as follows: the glassy carbon electrode surface is first polished with alumina polishing powder, and then ultrasonically cleaned with ethanol and deionized water for 5 min to 10 min respectively; in step (4), the drying is performed under an infrared lamp.

[0019] In the above-mentioned method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, preferably, in step (1), the Ti3C2T x The mass-to-volume ratio of nanosheets to N,N-dimethylformamide is 1 mg to 10 mg: 1 mL, and the ultrasonic dispersion time is 0.5 h to 3 h.

[0020] In the above-mentioned method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, preferably, in step (1), the Ti3C2T x The preparation process of the nanosheets is as follows: Multilayer Ti3AlC2 MXene powder is dispersed in water, with a mass-to-volume ratio of Ti3AlC2 MXene powder to water of 50mg-60mg:50mL-60mL. The solution is subjected to ultrasonic exfoliation in a water bath at room temperature for 4-8 hours. After the solution reaches a dark green colloidal state, it is freeze-dried to obtain Ti3C2T nanosheets. x Nanosheets.

[0021] As a general technical concept, the present invention also provides an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers prepared by the above-mentioned method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers.

[0022] As a general technical concept, the present invention also provides an application of the above-mentioned electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers in the detection of chloramphenicol.

[0023] The technical solution of this invention is mainly intended to solve the following problems of the prior art: (1) Solve the problem that the low electronic conduction efficiency of existing sensing interface materials leads to weak electrochemical oxidation-reduction response signal and high detection limit of chloramphenicol, which cannot meet the needs of trace chloramphenicol detection; (2) Solve the problem that the existing sensing materials cannot synergistically match the specific enrichment ability of chloramphenicol with the in-situ electrocatalytic activity, resulting in a narrow detection linear range and insufficient sensitivity, which cannot meet the needs of full concentration gradient detection in multiple scenarios. (3) To solve the problem that existing sensors have weak anti-interference ability in complex matrices and poor long-term stability, resulting in low detection accuracy and short service life, which cannot meet the needs of routine detection of actual samples. (4) Solve the problems of cumbersome preparation process, harsh reaction conditions, poor performance reproducibility between batches of existing composite sensing materials, which make it difficult to achieve large-scale preparation and industrialization.

[0024] To address the technical problems of existing technologies, this paper analyzes the root causes of their shortcomings and the insurmountable technical bottlenecks from the perspectives of material properties and technical principles. (1) The fundamental reason for low electron conduction efficiency: The core of chloramphenicol electrochemical detection relies on the electrocatalytic reaction of the target substance (i.e., chloramphenicol molecule) and the rapid transfer of electrons at the sensing interface. Although the commonly used single MOF-808 material has ultra-high specific surface area, regular nanopores and abundant Zr-O metal cluster active sites, its intrinsic semiconductor properties result in extremely poor conductivity and huge electron transfer impedance, which cannot efficiently transfer the electrons generated by the catalytic reaction to the electrode surface; while single Ti3C2T X While nanosheets possess excellent metal-like conductivity, the strong van der Waals forces and hydrogen bonds between their layers make them prone to irreversible self-stacking, leading to a significant decrease in the number of exposed active sites and a lack of specific adsorption capacity for chloramphenicol molecules. Existing physical blending processes can only achieve macroscopic contact between the two materials, failing to resolve the inherent contradiction between the insufficient conductivity of MOF-808 and the self-stacking of MXene layers. This prevents the construction of a continuous, interconnected three-dimensional electronic conduction network, thus failing to fundamentally improve the signal response capability of the sensing interface.

[0025] (2) The fundamental reason why enrichment capacity and electrocatalytic activity cannot be synergistic: High-sensitivity detection of chloramphenicol requires the sensing interface to simultaneously possess high-capacity specific enrichment of chloramphenicol and in-situ high-activity electrocatalysis of the enriched molecule. Although MOF-808 alone can specifically enrich chloramphenicol, its catalytic efficiency is low due to its limited conductivity; single Ti3C2T X Although it possesses conductivity and some catalytic ability, its enrichment capacity is weak, resulting in insufficient substrate concentration on the electrode surface. Existing technologies mostly introduce enrichment and catalytic units separately through stepwise modification. This spatial separation is not only cumbersome to prepare, but also disrupts the continuity of "target enrichment-in-situ electrocatalysis." The diffusion of target molecules between units leads to severe signal attenuation, making it impossible to achieve both a wide linear detection range and high sensitivity.

[0026] (3) The fundamental reasons for insufficient anti-interference ability and stability: On the one hand, the existing materials have insufficient specific recognition ability and are easily affected by the non-specific adsorption of coexisting antibiotics, inorganic salts and biomacromolecules in complex matrices, resulting in increased background noise. On the other hand, single MOF-808 is prone to Zr cluster shedding and framework collapse in liquid systems, and Ti3C2T X Surface-active end groups are highly susceptible to oxidation and inactivation. Existing technologies that improve specificity by modifying antibodies on the surface sacrifice conductivity and stability; while coating with inert polymers to improve stability masks the active sites. It is impossible to achieve a synergistic balance between the two in complex systems.

[0027] (4) The fundamental reason for the complex preparation process and poor reproducibility: Existing composite sensing materials mostly rely on multi-step discontinuous processes such as high-temperature calcination and stringent solvothermal in-situ growth, with extremely low parameter tolerance (small temperature or pH fluctuations can lead to changes in crystal phase or a sharp decrease in yield), which easily leads to significant differences in material morphology and the number of active sites between batches. In addition, physical blends are prone to agglomeration and sedimentation when formulated into film solutions, resulting in poor microscopic uniformity of electrode modification, which further aggravates the performance fluctuations between sensor batches, making it difficult to achieve large-scale preparation.

[0028] The main innovative points of this invention are as follows: (1) Using "MOF-808 in-situ confined growth + Ti3C2T" x The multi-level composite structure design of "intercalation support + carbon nanofiber three-dimensional skeleton" breaks through the structural limitations of existing technologies that rely on simple physical blending of MOF and MXene or multi-step layered growth. Through a combination of one-pot precursor solution preparation and electrospinning, the abundant electronegative end groups (-F, -OH, etc.) on the Ti3C2 surface are utilized to support Zr. 4+ The targeted coordination effect guides MOF-808 nanocrystals to nucleate and crystallize in situ within the pores of carbon nanofibers and on the surface of Ti3C2, ultimately forming a three-dimensional multilevel interpenetrating structure with continuous carbon nanofibers as the conductive framework, Ti3C2 as the fast electron transfer channel, and MOF-808 as the specific enrichment and catalytic site.

[0029] The core problem solved is that by utilizing the nanoscale spatial confinement and in-situ assembly effect, the irreversible aggregation of MOF-808 nanocrystals and the severe self-stacking of Ti3C2 sheets are suppressed from the root, maximizing the exposure of Zr-O cluster active sites. At the same time, strong electronic coupling between the two phase interfaces is achieved through the in-situ formed Zr-O-Ti chemical bonds, constructing a continuous and interconnected three-dimensional electronic conduction network.

[0030] Technical effects: The composite material of the present invention has an increased specific surface area and reduced electron transport impedance (R0). ct The detection performance of the composite material for chloramphenicol was significantly reduced.

[0031] (2) Breaking through the bottleneck of existing multi-step preparation processes, a controllable preparation technology of "one-pot electrospinning + one-step carbonization" was first created, which can transform Ti3C2T X After the dispersion, MOF-808 precursor, and spinning polymer are uniformly mixed in the same system, the stoichiometric ratio of each component is precisely "frozen" in the solid precursor fiber by electrospinning. The subsequent programmed heat treatment precisely utilizes the temperature window: in the early stage of heating, activation energy is provided to promote the smooth coordination and crystallization of MOF-808. Then, the carbonization shrinkage and interfacial crosslinking of the polymer are completed simultaneously, completely eliminating the cumbersome solvothermal reaction and multi-step ultrasonic intercalation process.

[0032] The core problem solved: This invention addresses the technical shortcomings of existing liquid-phase reaction systems, such as susceptibility to local concentration differences and low parameter tolerance. The solid-phase confined conversion process of this invention strictly constrains the chemical reaction path, greatly improving process tolerance and ensuring the successful conversion of MOF-808 and Ti3C2T. X Extremely uniform dispersion at the nanoscale.

[0033] Technical benefits: The main synthesis time is shortened from 8-24 hours in existing technologies to 4-8 hours, reducing energy consumption and raw material loss by more than 40%. The batch-to-batch structure of the prepared materials is highly consistent, and the relative standard deviation (RSD) of batch-to-batch test results is strictly controlled within 3%, perfectly meeting the requirements for large-scale mass production.

[0034] (3) To achieve an integrated synergistic sensing mechanism of "specific enrichment-in-situ electrocatalysis-rapid electron conduction", based on the molecular structure (hydroxyl, nitro functional groups) and electrochemical reduction characteristics of chloramphenicol, three functional units are spatially matched and synergistically designed: MOF-808 achieves rapid and high-capacity enrichment of chloramphenicol molecules through the pore confinement effect and the specific coordination of Zr-O clusters, and the adjacent Ti3C2T X Nanosheets perform in-situ efficient electrocatalytic reduction of enriched chloramphenicol molecules, while carbon nanofiber skeletons rapidly transfer the generated electrons to the electrode surface. The three are closely adjacent in space, achieving a seamless connection between "enrichment-catalysis-conduction".

[0035] The core problem solved is that the spatial separation of enrichment and catalytic units and the low efficiency of functional synergy in existing technologies are resolved, thus avoiding the loss of target material and signal attenuation during the diffusion process.

[0036] Technical effects: The electrocatalytic reduction peak current of chloramphenicol is increased by 2-3 times, the detection response time is shortened to less than 5 seconds, the linear range is broadened to 0.5-5000 nmol / L, and the detection limit is as low as 1.3 nmol / L, reaching the international advanced level.

[0037] (4) The one-pot electrospinning synthesis technology significantly improves the structure and electrochemical stability of the sensor. The composite precursor nanofiber membrane is spun on the surface of an aluminum foil roller using electrospinning technology. After carbonization, an integrated sensing membrane powder with strong adhesion to the electrode substrate is obtained. At the same time, the continuous carbon nanofiber framework supports MOF-808 and Ti3C2T x The spatial confinement protection inhibited the collapse of the MOF framework and Ti3C2T X Surface oxidation.

[0038] The core problem solved: It solved the problems of weak adhesion between the modified film and the electrode, easy detachment, easy loss of active materials, and poor long-term stability in the existing technology.

[0039] Technical results: After 30 consecutive uses, the response signal of the electrochemical sensor still retains more than 92% of the initial value; after 6 months of storage at room temperature, the response signal decays by less than 10%, and its service life is significantly better than that of existing electrochemical sensors.

[0040] Compared with the prior art, the advantages of the present invention are as follows: 1. This invention provides an in-situ crystallization preparation method combining one-pot electrospinning and simultaneous carbonization, achieving simple, efficient, and controllable preparation of sensing materials. This invention utilizes Ti3C2T... X Nanosheets, MOF-808 precursors (zirconium salt, organic ligands, and modifiers), and polyacrylonitrile matrix are homogeneously mixed in the same liquid phase. A one-step electrospinning technique is used to uniformly lock the stoichiometric ratios of each component into solid polymer nanofibers at the nanoscale. During subsequent programmed heat treatment, the spatial confinement effect of the polymer backbone enables adjacent zirconium salts and ligands to rapidly overcome the nucleation energy barrier with extremely short mass transfer distances, achieving high-conversion-rate, precise in-situ growth of MOF-808 nanocrystals and simultaneously completing the transformation of polyacrylonitrile into a carbon nanofiber matrix. This one-pot solid-phase locking and in-situ transformation route effectively avoids the loss of active raw materials and the formation of impurity phases caused by localized concentration inconsistencies in traditional multi-step liquid-phase synthesis. It significantly simplifies the preparation process, shortens the production cycle by several times, and significantly reduces preparation costs. Simultaneously, the precise controllability of the microstructure fundamentally ensures high batch-to-batch material homogeneity, laying a solid foundation for the large-scale, standardized preparation and industrialization of sensing interfaces.

[0041] 2. This invention constructs a composite carbon nanofiber material with a multi-level interconnected conductive network and highly monodisperse active sites, achieving a significant improvement in structural stability. This invention utilizes a three-dimensional carbon nanofiber network and a two-dimensional Ti3C2T... X The deep synergy of the conductive layers constructs a continuous and interconnected electron transport and mass diffusion system. This is thanks to Ti3C2T. XThe abundant electronegative end groups on the surface serve as heterogeneous nucleation sites, enabling MOF-808 nanocrystals to achieve targeted and confined growth on the surface of the sheets and within the carbon nanofiber framework. This effectively suppresses the irreversible aggregation of MOF-808 particles and Ti3C2T. X The severe self-stabilization of the layers forms a monodisperse, stable structure in which two-dimensional layers and three-dimensional nanocrystals are tightly anchored and interwoven. Simultaneously, the continuous carbon nanofiber framework supports the MOF-808 and Ti3C2T... X It provides comprehensive spatial confinement protection, effectively suppressing the collapse of the MOF-808 framework in the aqueous system and the Ti3C2T X Oxidative deactivation of surface-active end groups. Strong interfacial electronic coupling effects among multiple components and stable anchoring in the physical structure enable the composite material to achieve simultaneous leaps in active site density, conductive network integrity, and long-term structural stability.

[0042] 3. The electrochemical sensor constructed in this invention possesses ultra-sensitive, high-selectivity, fast-response, and long-term stable detection performance, meeting the detection requirements for trace amounts of chloramphenicol in complex real-world samples. Based on the aforementioned material advantages, the electrochemical sensor of this invention achieves the following performance improvements: (1) Through MOF-808 and Ti3C2T X The strong interfacial electronic coupling effect, combined with the continuous three-dimensional conductive network constructed by carbon nanofibers, fundamentally makes up for the conductivity defects of MOF-808, establishes an efficient interfacial charge transfer channel, significantly reduces electron transfer impedance, accelerates the kinetics of chloramphenicol electrocatalytic reduction reaction, broadens the detection linear range and shortens the response time, and adapts to the detection needs of chloramphenicol with different concentration gradients in multiple scenarios. (2) The spatial confinement and protection of the continuous carbon nanofiber framework effectively inhibited the hydrolysis and collapse of the MOF-808 framework in the aqueous detection system and the Ti3C2T X Oxidative deactivation of surface-active end groups. Simultaneously, MOF-808 nanocrystals are firmly anchored within the carbon nanofiber matrix and Ti3C2T through in-situ growth. X The sheet-like surface forms a tight physical embedding and chemical bonding interface, rather than the loose contact found in traditional physical blending systems. Thanks to this integrated and stable structure, the active material is less prone to detachment and loss in complex electrolyte environments and during long-term potential scanning, significantly extending the effective lifespan of the electrochemical sensor, ensuring the reproducibility and accuracy of repeated detections in complex matrices, and meeting the routine monitoring needs of actual samples. (3) Based on the molecular structure and electrochemical reduction characteristics of chloramphenicol, this invention focuses on the enrichment sites of MOF-808 and Ti3C2T. XThe catalytic sites were spatially matched and synergistically designed to achieve an integrated process of "specific enrichment-in-situ electrocatalysis," maximizing the exposure of the highly catalytically active Zr-O cluster-specific sites. Simultaneously, leveraging the pore confinement effect of MOF-808 and the specific coordination of the Zr-O cluster, the specific recognition ability for chloramphenicol was significantly improved, effectively suppressing the non-specific adsorption of interfering substances coexisting in complex matrices, and significantly enhancing the anti-interference capability and detection accuracy of the electrochemical sensor. Attached Figure Description

[0043] Figure 1 The MOF-808 / Ti3C2-CNFs / GCE of Example 1, the Ti3C2 / GCE of Comparative Example 1, and the MOF-808 / GCE of Comparative Example 2 are compared in [Fe(CN)6]. 3- / 4- The graph shows the electrochemical performance test results for [Fe(CN)6], where A represents the electrochemical performance of different electrochemical sensors. 3- / 4- Electrochemical impedance spectroscopy in solution, B represents different electrochemical sensors in [Fe(CN)6] 3- / 4- Cyclic voltammetry curves in solution.

[0044] Figure 2 This is a comparison chart of the chloramphenicol detection performance of MOF-808 / Ti3C2-CNFs / GCE in Example 1, Ti3C2 / GCE in Comparative Example 1, and MOF-808 / GCE in Comparative Example 2. In the chart, A is the cyclic voltammetry curve of different electrochemical sensors in a phosphate buffer solution containing 5 μM chloramphenicol; B is a three-dimensional bar chart of the oxidation and reduction peak currents of the cyclic voltammetry of different electrochemical sensors; C is the differential pulse voltammetry curve of different electrochemical sensors in a phosphate buffer solution containing 5 μM chloramphenicol; and D is a three-dimensional bar chart of the oxidation peak current of the differential pulse voltammetry of different electrochemical sensors.

[0045] Figure 3 The diagram shows the pH optimization of the phosphate buffer solution during electrochemical testing of the electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers prepared in Example 1 of this invention. In this diagram, A is the cyclic voltammetry curve at pH values ​​of 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, and 7.5; B is the relationship between the oxidation peak current and the reduction peak current and the pH value; and C is the linear relationship between the average potential values ​​of the oxidation peak potential, the reduction peak potential, and the redox potential and the pH value.

[0046] Figure 4The figure shows the optimized titration volume of the electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers prepared in Example 1 of this invention during differential pulse voltammetry testing in a phosphate buffer solution containing 5 μM chloramphenicol. In the figure, A is the differential pulse voltammetry curve of the electrochemical sensor in a phosphate buffer solution containing 5 μM chloramphenicol with titration volumes of 2, 4, 6, and 8 μL, and B is the relationship between the oxidation peak current and the titration volume of the electrochemical sensor.

[0047] Figure 5 The diagram shows the optimization of the enrichment potential during differential pulse voltammetry testing of the electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers prepared in Example 1 of this invention. In this diagram, A is the differential pulse voltammetry curve at enrichment potentials of -0.3V, -0.2V, -0.1V, 0V, 0.1V, 0.2V, 0.3V, and 0.4V, and B is the oxidation peak current diagram of the electrochemical sensor at different enrichment potentials.

[0048] Figure 6 The diagram shows the optimization of enrichment time during differential pulse voltammetry testing of the electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers prepared in Example 1 of this invention. In this diagram, A is the differential pulse voltammetry curve at enrichment times of 0s, 30s, 60s, 90s, 120s, 150s, 180s, 210s, 240s, 270s, 300s, 330s, and 360s, and B is the oxidation peak current diagram of the electrochemical sensor at different enrichment times.

[0049] Figure 7 The graphs show the performance of the electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers prepared in Example 1 of this invention for the quantitative detection of chloramphenicol at different concentrations. In the graphs, A is the differential pulse voltammetry curve of the electrochemical sensor in phosphate buffer solutions containing chloramphenicol at concentrations of 0.5 nM, 1 nM, 5 nM, 50 nM, 100 nM, 200 nM, 500 nM, 800 nM, 1000 nM, 2000 nM, and 5000 nM, respectively. B is the linear relationship between the differential pulse voltammetry oxidation peak current and the concentration of chloramphenicol. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available, and the unit M represents mol / L.

[0051] Example 1 A method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers according to the present invention includes the following steps: (1) Weigh 50 mg of multilayer Ti3AlC2 MXene powder (available from Scientific Compass) and disperse it in 50 mL of ultrapure water. Perform ultrasonic exfoliation in a water bath at room temperature for 4 h. After the solution turns into a dark green colloidal state, freeze dry it to finally collect highly exfoliated few-layer Ti3C2T x Nanosheet powder. Weigh 0.05g of the above-prepared Ti3C2T x The nanosheet powder was added to 10 mL of N,N-dimethylformamide (DMF) and ultrasonically dispersed for 1 h to obtain a Ti3C2 nanosheet dispersion.

[0052] (2) Add 0.5 mmol of ZrOCl2·8H2O and 0.25 mmol of trimesic acid (BTC) sequentially to 10 mL of Ti3C2 nanosheet dispersion obtained in step (1). Stir magnetically at room temperature until completely dissolved. After the solution becomes clear, add 1.0 mL of formic acid, and then slowly add 1.0 g of polyacrylonitrile (PAN). Stir continuously at room temperature for 24 h until a viscous and homogeneous electrospinning precursor solution is obtained. Transfer the electrospinning precursor solution to a 5 mL syringe and perform electrospinning at a spinning voltage of 10 kV and a feed rate of 0.5 mL / h. Use aluminum foil rollers as the receiving substrate and a receiving distance of 15 cm. Place the collected composite fiber membrane in a 60 °C oven and dry for 12 h to completely remove residual solvent, and obtain a composite nanofiber membrane loaded with MOF-808 precursor and Ti3C2 nanosheets. The fiber diameter is about 400 nm and the membrane thickness is about 5 μm.

[0053] (3) The composite nanofiber membrane loaded with MOF-808 precursor and Ti3C2 nanosheets obtained above was cut into 2cm × 2cm square pieces, laid flat in a quartz boat and placed in a tube furnace. Under nitrogen atmosphere protection, it was first heated to 260℃ for pre-oxidation treatment for 2h at a heating rate of 2℃ / min, and then heated to 900℃ for carbonization treatment for 2h at a heating rate of 5℃ / min. During this process, the precursor in the solid confined space underwent in-situ coordination crystallization to form MOF-808 nanocrystals with a particle size of about 50nm, and the interface coupling was completed simultaneously with the carbonization of PAN. After naturally cooling to room temperature, the product was taken out and thoroughly ground in an agate mortar to obtain MOF-808 / titanium carbide composite carbon nanofiber powder.

[0054] (4) 10 mg of MOF-808 / titanium carbide composite carbon nanofiber powder was added to 5 mL of deionized water and ultrasonically dispersed for 15 min to obtain a dispersion of MOF-808 / titanium carbide composite carbon nanofiber with a concentration of 2.0 mg / mL. The surface of the glassy carbon electrode was first polished with alumina polishing powder, and then ultrasonically cleaned with ethanol and deionized water for 5 min each to obtain a pretreated glassy carbon electrode. 4 µL of the MOF-808 / titanium carbide composite carbon nanofiber dispersion was pipetted onto the surface of the pretreated glassy carbon electrode and dried under an infrared lamp to obtain a modified electrode based on MOF-808 / titanium carbide composite carbon nanofiber.

[0055] (5) Using the modified electrode based on MOF-808 / titanium carbide composite carbon nanofiber as the working electrode, the platinum wire electrode as the counter electrode, and Ag / AgCl as the reference electrode, a three-electrode working system was constructed to obtain an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofiber, denoted as MOF-808 / Ti3C2-CNFs / GCE.

[0056] Comparative Example 1 A method for preparing a Ti3C2-modified electrochemical sensor (Ti3C2 / GCE) includes the following steps: (1) Weigh 50 mg of multilayer Ti3AlC2 MXene powder and disperse it in 50 mL of ultrapure water. Perform ultrasonic exfoliation in a water bath at room temperature for 4 h. After the solution turns into a dark green colloidal state, freeze dry it to finally collect highly exfoliated few-layer Ti3C2T x Nanoparticle powder.

[0057] (2) Weigh 10 mg of the few-layer Ti3C2T prepared above. x The nanosheet powder was added to 5 mL of deionized water and ultrasonically dispersed for 15 min to obtain a Ti3C2 nanosheet dispersion with a concentration of 2 mg / mL.

[0058] (3) Polish the surface of the glassy carbon electrode with alumina polishing powder, and then clean it with ethanol and deionized water for 5 min each to obtain a pretreated glassy carbon electrode. Use a pipette to transfer 4 µL of the Ti3C2 nanosheet dispersion obtained in step (2) and drop it directly onto the surface of the pretreated glassy carbon electrode. After drying under an infrared lamp, a Ti3C2 modified glassy carbon electrode is obtained.

[0059] (4) Using a Ti3C2-modified glassy carbon electrode as the working electrode, a platinum wire electrode as the counter electrode, and Ag / AgCl as the reference electrode, a three-electrode working system was constructed to obtain a Ti3C2-modified electrochemical sensor, denoted as Ti3C2 / GCE.

[0060] Comparative Example 2 A method for preparing a pure MOF-808 modified electrochemical sensor (MOF-808 / GCE) includes the following steps: (1) Weigh 0.5 mmol ZrOCl2·8H2O and 0.25 mmol trimesic acid (BTC) and dissolve them in a mixture of 10 mL N,N-dimethylformamide (DMF) and 1.0 mL formic acid. Stir magnetically at room temperature until completely dissolved. Transfer the resulting mixture to a stainless steel reactor lined with polytetrafluoroethylene and react at 120 °C for 24 h. After the reaction is complete, allow it to cool naturally to room temperature, centrifuge to collect the precipitate, wash it three times each with DMF and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60 °C for 12 h to obtain pure MOF-808 powder.

[0061] (2) Weigh 10 mg of the pure MOF-808 powder prepared above, add it to 5 mL of deionized water, and ultrasonically disperse for 15 min to obtain MOF-808 dispersion with a concentration of 2 mg / mL.

[0062] (3) Polish the surface of the glassy carbon electrode with alumina polishing powder, and then clean it with ethanol and deionized water for 5 min each to obtain a pretreated glassy carbon electrode. Use a pipette to transfer 4 µL of the MOF-808 dispersion obtained in step (2) and drop it directly onto the surface of the pretreated glassy carbon electrode. After drying under an infrared lamp, a pure MOF-808 modified glassy carbon electrode is obtained.

[0063] (4) Using a glassy carbon electrode modified with pure MOF-808 as the working electrode, a platinum wire electrode as the counter electrode, and Ag / AgCl as the reference electrode, a three-electrode working system was constructed to obtain an electrochemical sensor modified with pure MOF-808, denoted as MOF-808 / GCE.

[0064] Electrochemical test parameters The electrochemical sensor described above was tested on a CHI660 electrochemical workstation using a 0.1 M phosphate buffer solution (i.e., PBS buffer). Cyclic voltammetry (CV) was performed at a scan rate of 100 mV·s. -1 The potential window is -0.6V to 0.6V. In differential pulse voltammetry (DPV), the pulse amplitude is 0.05V, the pulse period is 0.2s, and the potential window is -0.6V to 0.6V. In electrochemical impedance spectroscopy (EIS), the frequency range is 0.01Hz to 105Hz, the amplitude is 5mV, and the supporting electrolyte contains 5.0mM [Fe(CN)6]. 3- / 4-A 0.1M KCl solution was used. All current directions were set with the anode positive. Furthermore, the electrolyte solution was purged with nitrogen for 10 minutes before all tests, and the nitrogen atmosphere was maintained throughout the subsequent experiments.

[0065] 1. Evaluation of the electrochemical performance of different electrochemical sensors The electrochemical performance of MOF-808 / Ti3C2-CNFs / GCE in Example 1, Ti3C2 / GCE in Comparative Example 1, and MOF-808 / GCE in Comparative Example 2 was evaluated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Figure 1 As shown in Figure A, at 5.0 mM [Fe(CN)6] 3- / 4- In the probe system, all three electrochemical sensors exhibited typical charge transfer impedance responses. Among them, MOF-808 / Ti3C2-CNFs / GCE showed the lowest electron transfer impedance (Rct), significantly lower than Ti3C2 / GCE and MOF-808 / GCE, indicating that the composite material modification of this invention effectively improved the electron transport capability at the electrode interface. Figure 1 As shown in Figure B, the electron transfer behavior of different electrochemical sensors was further analyzed using CV curves. Compared with Ti3C2 / GCE and MOF-808 / GCE, MOF-808 / Ti3C2-CNFs / GCE exhibited higher oxidation and reduction peak currents and a smaller inter-peak potential difference. This indicates that a synergistic effect occurred between the Ti3C2-CNFs conductive network and the MOF-808 porous structure, improving the charge transport efficiency and electrocatalytic activity of the electrode surface. These results demonstrate that the MOF-808 / Ti3C2-CNFs / GCE constructed in this invention possesses excellent electron transport capabilities, providing a foundation for subsequent highly sensitive detection of chloramphenicol.

[0066] 2. Comparison of the detection performance of different electrochemical sensors for chloramphenicol To verify the enhancing effect of MOF-808 / Ti3C2-CNFs / GCE on chloramphenicol detection performance, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to compare Ti3C2 / GCE, MOF-808 / GCE, and MOF-808 / Ti3C2-CNFs / GCE under the same experimental conditions. Figure 2 A, Figure 2As shown in Figure B, different electrochemical sensors all exhibited characteristic oxidation peak currents of chloramphenicol. Positive current values ​​indicate oxidation peak currents, while negative values ​​indicate reduction peak currents. Among them, Ti3C2 / GCE showed a certain electrocatalytic response, indicating that Ti3C2 material can promote electron transport. MOF-808 / GCE also showed a certain response, mainly due to the adsorption and enrichment of chloramphenicol molecules by its porous structure. The MOF-808 / Ti3C2-CNFs / GCE of this invention showed a significantly enhanced current response. Figure 2 C Figure 2 As can be further seen from D, the chloramphenicol oxidation peak current of MOF-808 / Ti3C2-CNFs / GCE is significantly higher than that of Ti3C2 / GCE and MOF-808 / GCE. This indicates that MOF-808 / Ti3C2-CNFs / GCE of the present invention effectively synergizes the excellent conductivity of Ti3C2-CNFs with the abundant adsorption sites of MOF-808, thereby improving the enrichment efficiency and electron transfer rate of chloramphenicol molecules on the electrode surface. Therefore, MOF-808 / Ti3C2-CNFs / GCE of the present invention has superior chloramphenicol detection performance compared to Ti3C2 / GCE and MOF-808 / GCE.

[0067] 3. Optimization of test conditions (1) Optimal pH value The pH of the PBS buffer solution affects the charge state, molecular diffusion behavior, and electron / proton transfer processes at the electrode interface of chloramphenicol, thus significantly influencing the sensor's detection performance. To obtain optimal detection conditions, cyclic voltammetry was used to investigate the electrochemical response of MOF-808 / Ti3C2-CNFs / GCE to chloramphenicol in PBS buffer solutions at different pH values ​​(4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5). Figure 3 As shown in Figure A, as the pH of the PBS buffer solution increased from 4.5 to 6.5, the oxidation and reduction peak currents of chloramphenicol gradually increased, indicating that a suitable weakly acidic environment is conducive to the adsorption and enrichment of chloramphenicol molecules on the modified electrode surface and the electrocatalytic oxidation reaction. When the pH continued to rise to 7.5, the redox peak currents gradually decreased, possibly due to the change in the protonation state of chloramphenicol molecules, leading to a weakening of its interaction with the electrode interface, thereby reducing the charge transfer efficiency. Figure 3 As shown in B, the oxidation and reduction peak currents of chloramphenicol exhibit a trend of first increasing and then decreasing with pH, ​​reaching their maximum response values ​​at pH=6.5. This indicates that under these conditions, MOF-808 / Ti3C2-CNFs / GCE can achieve the optimal electrochemical response to chloramphenicol molecules. Meanwhile, as... Figure 3As shown in Figure C, the oxidation peak potential, reduction peak potential, and average peak potential all exhibit a good linear relationship with pH value, indicating that the electrocatalytic oxidation process of chloramphenicol involves an electrochemical reaction process involving protons. Therefore, based on the current response value, a PBS buffer system with pH=6.5 was selected as the optimal experimental condition for subsequent chloramphenicol detection. This optimized condition can maximize the electrochemical response of the electrochemical sensor to chloramphenicol, providing a guarantee for achieving highly sensitive and accurate quantitative detection.

[0068] (2) Titration volume The effect of varying the volume of a dispersion based on MOF-808 / titanium carbide composite carbon nanofibers dropped onto the surface of a pretreated glassy carbon electrode on the detection response of chloramphenicol was investigated. Figure 4 A, Figure 4 As shown in Figure B, the oxidation peak current of chloramphenicol gradually increased with the increase of the dropping volume from 2 μL to 4 μL, indicating that appropriately increasing the loading of the composite material can provide more active sites, which is beneficial to the adsorption and electrocatalytic reaction of chloramphenicol molecules. When the dropping volume continued to increase, the oxidation peak current decreased, possibly because the excessively thick modification layer reduced the electron transport efficiency and restricted the diffusion of chloramphenicol molecules to the electrode surface. Therefore, 4 μL was selected as the optimal modification amount.

[0069] (3) Enrichment potential like Figure 5 As shown in Figure A, the chloramphenicol oxidation peak current changes significantly under different potential conditions. When the potential gradually increases from -0.3V to 0.2V, the oxidation peak current continuously increases, reaching its maximum value at 0.2V. Figure 5 As shown in Figure B, the oxidation peak current first increases and then decreases with the enrichment potential, reaching its peak value at 0.2V. This indicates that 0.2V can effectively promote the enrichment of chloramphenicol molecules on the electrode surface while avoiding side reactions caused by excessively high potentials. Therefore, 0.2V was chosen as the optimal enrichment potential.

[0070] (4) Enrichment time To further optimize the detection performance of MOF-808 / Ti3C2-CNFs / GCE for chloramphenicol, DPV technology was used to test the effect of enrichment time. For example... Figure 6 As shown in Figure A, the chloramphenicol oxidation peak current gradually increased with the enrichment time increasing from 0 s to 360 s, indicating that the MOF-808 pore structure of the composite material in MOF-808 / Ti3C2-CNFs / GCE can continuously adsorb chloramphenicol molecules. Figure 6 As shown in Figure B, when the enrichment time exceeds 300 seconds, the oxidation peak current begins to decrease slowly, indicating that the adsorption sites on the electrode surface gradually reach saturation. Therefore, 300 seconds was chosen as the optimal enrichment time.

[0071] 4. Quantitative detection performance of MOF-808 / Ti3C2-CNFs / GCE for chloramphenicol Under the aforementioned optimal conditions (pH=6.5, enrichment potential 0.2V, enrichment time 300s), the response behavior of MOF-808 / Ti3C2-CNFs / GCE to different concentrations of chloramphenicol was studied using the DPV method. Figure 7 As shown in Figure A, the oxidation peak current gradually increased as the concentration of chloramphenicol in phosphate buffer solution increased from 0.5 nM to 5000 nM, indicating that MOF-808 / Ti3C2-CNFs / GCE can effectively respond to chloramphenicol in different concentration ranges. Figure 7 As shown in Figure B, when MOF-808 / Ti3C2-CNFs / GCE is used as the modified electrode, the current exhibits a linear relationship in the two concentration ranges of 0.5nM-100nM and 100nM-5000nM, respectively. The following equation is obtained by fitting the data: y1 = 0.1250x + 1.904, R 2 =0.9979 Formula (I) In equation (I), y1 is the oxidation peak current of chloramphenicol in μA, x is the concentration of chloramphenicol in nM, and 0.5nM≤x≤100nM; y² = 0.0119x + 14.343, R 2 =0.9978 Equation (II) In equation (II), y2 is the oxidation peak current of chloramphenicol in μA, x is the concentration of chloramphenicol in nM, and 100nM < x ≤ 5000nM.

[0072] Therefore, the detection linear range of MOF-808 / Ti3C2-CNFs / GCE for chloramphenicol in this invention is 0.5nM-5000nM, which can be divided into two linear segments. The detection limit (LOD) is calculated to be 1.3nM (S / N=3), which shows that MOF-808 / Ti3C2-CNFs / GCE of this invention has good quantitative analysis capability.

[0073] This invention utilizes "MOF-808 in-situ confined growth + Ti3C2T" xThe multi-level composite structure design of "intercalation support + three-dimensional carbon nanofiber skeleton" overcomes the pain points of poor material conductivity, easy stacking and agglomeration, and cumbersome processes in existing technologies, achieving significant progress in detection performance, preparation process, and stability. In terms of detection performance, the composite material of this invention exhibits significantly improved specific surface area and adsorption capacity, significantly reduced electron transfer impedance, a broadened linear range to 0.5 nM-5000 nM, and a detection limit as low as 1.3 nmol / L. In summary, the electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers prepared in this invention successfully combines the advantages of ultra-high detection sensitivity and efficient, low-consumption preparation, showing great application potential.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers, characterized in that, Includes the following steps: (1) Ti3C2T x The nanosheets were added to N,N-dimethylformamide and dispersed by ultrasonication to obtain a Ti3C2 nanosheet dispersion; (2) Zirconium salt, pyromellitic acid, formic acid and polyacrylonitrile were added sequentially to the Ti3C2 nanosheet dispersion obtained above and stirred at room temperature to dissolve, so as to obtain an electrospinning precursor solution. The electrospinning precursor solution was electrospinned with a spinning voltage of 10kV to 20kV, a feed rate of 0.5mL / h to 2mL / h, and a receiving distance of 10cm to 20cm. After electrospinning, the solution was dried to obtain a composite nanofiber membrane loaded with MOF-808 precursor and Ti3C2 nanosheets. (3) The composite nanofiber film loaded with MOF-808 precursor and Ti3C2 nanosheets obtained above is first heated to 200℃~300℃ for pre-oxidation treatment under nitrogen atmosphere, and then heated to 600℃~900℃ for carbonization treatment to achieve MOF-808 crystallization, polyacrylonitrile carbonization and interface coupling. After cooling and grinding, MOF-808 / titanium carbide composite carbon nanofiber powder is obtained. (4) The above-obtained MOF-808 / titanium carbide composite carbon nanofiber powder is added to a solvent and ultrasonically dispersed to obtain a dispersion of MOF-808 / titanium carbide composite carbon nanofiber. The dispersion is then drop-coated onto the surface of a pretreated glassy carbon electrode and dried to obtain a modified electrode based on MOF-808 / titanium carbide composite carbon nanofiber. (5) Using the modified electrode based on MOF-808 / titanium carbide composite carbon nanofiber as the working electrode, the platinum wire electrode as the counter electrode, and Ag / AgCl as the reference electrode, a three-electrode working system is constructed to obtain an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofiber.

2. The method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers according to claim 1, characterized in that, In step (2), the molar ratio of zirconium salt to trimesic acid is 2-4:1, the molar volume ratio of trimesic acid to Ti3C2 nanosheet dispersion is 0.025mmol-0.052mmol:1mL, the volume of formic acid is 5%-20% of the volume of Ti3C2 nanosheet dispersion, and the mass-volume ratio of polyacrylonitrile to Ti3C2 nanosheet dispersion is 0.1g-0.5g:1mL; the zirconium salt is zirconium oxynitrate hydrate or zirconium oxychloride octahydrate.

3. The method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers according to claim 1, characterized in that, In step (3), the heating rate of the pre-oxidation treatment is 1℃ / min to 3℃ / min, the pre-oxidation treatment time is 1h to 3h, the heating rate of the carbonization treatment is 2℃ / min to 5℃ / min, the carbonization treatment time is 1h to 3h, and the MOF-808 is crystallized to obtain MOF-808 nanocrystals with a particle size of 20nm to 100nm.

4. The method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers according to any one of claims 1 to 3, characterized in that, In step (2), the drying temperature is 60℃~80℃, the drying time is 12h~16h, the fiber diameter of the composite nanofiber membrane loaded with MOF-808 precursor and Ti3C2 nanosheets is 200nm~800nm, and the thickness of the composite nanofiber membrane loaded with MOF-808 precursor and Ti3C2 nanosheets is 1μm~10μm.

5. The method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers according to any one of claims 1 to 3, characterized in that, In step (4), the mass-to-volume ratio of the MOF-808 / titanium carbide composite carbon nanofiber powder to the solvent is 2 mg to 4 mg: 1 mL, the solvent is water, and the ultrasonic dispersion time is 15 min to 30 min.

6. The method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers according to any one of claims 1 to 3, characterized in that, In step (4), the pretreatment process of the glassy carbon electrode surface is as follows: the glassy carbon electrode surface is first polished with alumina polishing powder, and then ultrasonically cleaned with ethanol and deionized water for 5 min to 10 min respectively; in step (4), the drying is done under infrared lamp.

7. The method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers according to any one of claims 1 to 3, characterized in that, In step (1), the Ti3C2T x The mass-to-volume ratio of nanosheets to N,N-dimethylformamide is 1 mg to 10 mg: 1 mL, and the ultrasonic dispersion time is 0.5 h to 3 h.

8. The method for preparing an electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers according to any one of claims 1 to 3, characterized in that, In step (1), the Ti3C2T x The preparation process of the nanosheets is as follows: Multilayer Ti3AlC2 MXene powder is dispersed in water, with a mass-to-volume ratio of Ti3AlC2 MXene powder to water of 50mg-60mg:50mL-60mL. The solution is subjected to ultrasonic exfoliation in a water bath at room temperature for 4-8 hours. After the solution reaches a dark green colloidal state, it is freeze-dried to obtain Ti3C2T nanosheets. x Nanosheets.

9. An electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers prepared by any one of claims 1 to 8.

10. The application of the electrochemical sensor based on MOF-808 / titanium carbide composite carbon nanofibers as described in claim 9 in the detection of chloramphenicol.

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