A non-enzyme glucose sensor based on ni doping and a preparation method and application thereof

Abstract

This invention relates to the field of non-enzymatic glucose sensor technology, and particularly to a Ni-doped non-enzymatic glucose sensor, its preparation method, and its application. The method includes the following steps: cleaning and naturally drying a titanium wire, followed by constant-voltage deposition in a fluorine-containing electrolyte to obtain a Ti / TiO2 bilayer structure; annealing in air, followed by heating in an argon atmosphere, introducing a mixed atmosphere of hydrogen and a carbon source, holding at this temperature, stopping the gas introduction, and cooling to room temperature in an argon atmosphere to obtain a C / TiO2 / Ti multilayer structure; and finally, constant-voltage deposition in a nickel-containing mixed electrolyte to obtain the non-enzymatic glucose sensor. Using the above steps, the non-enzymatic glucose sensor obtained exhibits excellent catalytic activity for glucose oxidation in 0.1M NaOH solution, showing good linearity in the concentration range of 0.01–5.78 mM, with a sensitivity reaching 2624 μA·mM. ‑1 ·cm ‑2 The detection limit is approximately 0.5 μM, and the current response time is less than 2 s.

Description

Technical Field

[0001] This invention relates to the field of non-enzymatic glucose sensor technology, and in particular to a Ni-doped non-enzymatic glucose sensor, its preparation method, and its application. Background Technology

[0002] Traditional commercial glucose sensors are mostly based on enzymatic systems such as glucose oxidase (GOx), which offer high selectivity. However, enzyme activity is highly susceptible to environmental factors such as temperature, pH, humidity, and storage conditions, leading to insufficient stability and short lifespan. Furthermore, the enzyme preparation and immobilization processes increase sensor costs. Therefore, constructing non-enzymatic glucose sensors with high stability, high sensitivity, and simple fabrication has become a current research hotspot.

[0003] Among numerous non-enzymatic electrocatalytic systems, transition metals and their oxides (such as Ni, Co, and Cu) have attracted widespread attention due to their reversible redox properties, tunable multivalent states, and excellent electrocatalytic performance. Ni-based materials, in particular, exhibit excellent catalytic activity under alkaline conditions by participating in the electrocatalytic oxidation of glucose through the Ni(OH)₂ / NiOOH oxygen pair, making them one of the fastest-growing classes of non-enzymatic glucose sensing materials. However, single Ni nanomaterials are prone to aggregation, resulting in insufficient exposure of active sites, and their conductivity and mechanical stability are limited, making it difficult to maintain stable operation in complex environments over long periods.

[0004] To overcome the aforementioned problems, loading Ni onto an inorganic substrate with a highly ordered structure and good conductivity is an effective strategy. Anodized Ti-based TiO2 nanotube arrays (TNTs) possess characteristics such as vertical alignment, uniform pore size, large specific surface area, and good biocompatibility, providing a stable loading platform and continuous electron conduction pathways for metal catalysts. However, the poor conductivity of TiO2 itself limits its further application in high-performance non-enzymatic electrodes. Summary of the Invention

[0005] The purpose of this invention is to provide a Ni-doped non-enzymatic glucose sensor, its preparation method and application. Nickel nanoparticles are successfully loaded onto the surface of a C / TiO2 / Ti multilayer structure. There is a significant interaction between the carbon layer and metallic nickel, and more structural defects and electrochemical active sites are introduced.

[0006] To achieve the above objectives, the present invention provides a method for preparing a Ni-doped non-enzymatic glucose sensor, comprising the following steps: S1. After cleaning the titanium wire, it is naturally dried. The dried titanium wire is used as the working electrode and the platinum sheet is used as the counter electrode. Constant voltage deposition is carried out in a fluorine-containing electrolyte to obtain a Ti / TiO2 bilayer structure. S2. The Ti / TiO2 bilayer structure obtained in S1 is placed in a tube furnace and annealed in an air atmosphere. Then, it is heated to 700-900℃ in an argon atmosphere, and a mixed atmosphere of hydrogen and carbon source is introduced. After holding at this temperature for 0.5-2 hours, the gas inlet is stopped, and the temperature is lowered to room temperature in an argon atmosphere to obtain a C / TiO2 / Ti multilayer structure. S3. The C / TiO2 / Ti multilayer structure obtained in S2 is placed in a nickel-containing mixed electrolyte for constant potential deposition to obtain a non-enzymatic glucose sensor electrode.

[0007] Preferably, in step S1, the titanium wire is cleaned sequentially using ethanol, acetone, and ethanol.

[0008] Preferably, in S1, the fluorinated electrolyte is a 0.1-0.5M ammonium fluoride solution, the constant voltage for constant voltage deposition is 40-80V, and the constant voltage deposition is carried out at 20-30℃ for 4-8 hours.

[0009] Preferably, in S2, the annealing temperature is 500-600℃ and the annealing time is 0.5-3h.

[0010] Preferably, in S2, the carbon source is acetylene.

[0011] Preferably, in S3, the nickel-containing mixed electrolyte includes nickel sulfate and sodium sulfate mixed in a volume ratio of 2-4:1, with the concentration of nickel sulfate being 20-50 mM and the concentration of sodium sulfate being 0.05-0.2 M.

[0012] Preferably, in S3, the voltage for constant potential deposition is -0.5V to -2V, and the time for constant potential deposition is 100-200s.

[0013] Preferably, in S3, the potentiostatic deposition uses a C / TiO2 / Ti multilayer structure as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode.

[0014] The above-described method for preparing a Ni-doped non-enzymatic glucose sensor yields a non-enzymatic glucose sensor.

[0015] The aforementioned Ni-doped non-enzymatic glucose sensor is used to detect glucose in liquids.

[0016] Therefore, the present invention employs the above-mentioned Ni-doped non-enzymatic glucose sensor, its preparation method, and its application, the beneficial effects of which are as follows: 1. This invention uses titanium wire as a flexible substrate, constructs TiO2 nanotube arrays (TNTs) through anodic oxidation, and obtains carbon-modified TiO2 nanotubes (C / TiO2 / Ti multilayer structure) by annealing in an acetylene / hydrogen atmosphere. Then, nickel nanoparticles are loaded by electrodeposition to construct Ni@CTNT filamentous non-enzymatic glucose sensor electrode. 2. In the non-enzymatic glucose sensor provided by this invention, nickel nanoparticles are successfully loaded onto the surface of CTNT (carbon-modified TiO2 nanotubes). A significant interaction exists between the carbon layer and metallic nickel, introducing more structural defects and electrochemical active sites. The Ni@CTNT electrode exhibits excellent catalytic activity for glucose oxidation in 0.1M NaOH solution, showing good linearity in the concentration range of 0.01-5.78 mM, with a sensitivity reaching 2624 μA·mM. -1 ·cm -2 The detection limit is approximately 0.5 μM, and the current response time is less than 2 s. 3. The non-enzymatic glucose sensor electrode provided by this invention has good anti-interference ability against common interfering substances (AA, UA, DA) and achieves satisfactory recovery rate in the detection of real beverage samples, indicating that the Ni@CTNT filamentous non-enzymatic glucose sensor has good application prospects in flexible and wearable non-enzymatic glucose sensors.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 These are the XRD patterns of Ni@CTNT in Embodiment 1 of the present invention and CTNT in the comparative example; Figure 2 These are the Raman spectra of Ni@CTNT in Example 1 of this invention and CTNT in the comparative example; Figure 3 This is a SEM image of CTNT in the comparative example of this invention, wherein, Figure 3 (a) is a SEM image at 100 μm. Figure 3 (b) is the SEM image at 5 μm. Figure 3 (c) in the image is the SEM image at 1 μm; Figure 4 This is a combined SEM and EDS image of Ni@CTNT in Embodiment 1 of the present invention, wherein, Figure 4 (a) is a SEM image at 50 μm. Figure 4 (b) is the SEM image at 1 μm. Figure 4 (c) in the image is the SEM image at 500nm. Figure 4 (d) in the figure is the EDS plot of Ni element. Figure 4 (e) in the diagram is the EDS plot of element C. Figure 4 (f) in the figure is the EDS plot of the Ti element. Figure 4 (g) in the diagram represents the EDS plot of element O; Figure 5 This is an XPS composite image of Ni@CTNT in Example 1, wherein, Figure 5(a) in the image is the full spectrum. Figure 5 (b) in the image is the high-resolution C1s spectrum. Figure 5 (c) in the image is the high-resolution O1s spectrum. Figure 5 (d) in the image is the high-resolution spectrum of Ti2p. Figure 5 (e) in the image is the high-resolution Ni2p spectrum; Figure 6 This is a combined electrochemical performance diagram of Ni@CTNT in Example 1 and CTNT in the comparative example, wherein, Figure 6 (a) in the figure is a cyclic voltammetry curve with and without the addition of 1 mM glucose in a 0.1 M NaOH solution; Figure 6 (b) in the figure shows the cyclic voltammetry curves of the Ni@CTNT electrode with different concentrations of glucose added to 0.1M NaOH solution; Figure 6 (c) represents the Ni@CTNT electrode at different scan rates (25-125 mvs) in 0.1 M NaOH. -1 The cyclic voltammetry curve of ) Figure 6 (d) in the figure is a linear fit plot of the oxidation peak current and reduction peak current of the cyclic voltammetry with the first power of the scan rate at different scan rates. Figure 7 This is a combined test diagram for Ni@CTNT detection of glucose in Embodiment 1 of the present invention, wherein, Figure 7 (a) shows the current versus time curves for seven additions of 0.5 mM glucose to 0.1 M NaOH solution at 50 s intervals under different voltages (0.55-0.65 V). Figure 7 (b) shows the current versus time curves obtained when different concentrations of glucose are added sequentially to a 0.1M NaOH solution at a voltage of 0.6V. Figure 7 (c) in the figure is a linear fit graph of the response current and the glucose concentration in the alkaline solution. Figure 7 (d) in the figure is the curve of current versus time after the addition of the interfering substance; Figure 8 This is a performance combination diagram of Ni@CTNT in Example 1 and CTNT in the comparative example, wherein, Figure 8 (a) in the figure is the current response diagram of Ni@CTNT. Figure 8 (b) in the figure is the EIS Nyquist plot of Ni@CTNT and CTNT. Figure 8 (c) in the figure shows the CV curves of multiple Ni@CTNTs. Figure 8 (d) in the figure represents the response current diagram of multiple Ni@CTNTs. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0020] This invention provides a method for preparing a Ni-doped non-enzymatic glucose sensor, comprising the following steps: S1. After cleaning and air-drying, the dried titanium wire is used as the working electrode and a platinum sheet as the counter electrode. Constant voltage deposition is performed in a fluorinated electrolyte to obtain a Ti / TiO2 bilayer structure. Cleaning the titanium wire removes grease, organic contaminants, and oxide layer debris from its surface to obtain a clean surface, allowing for subsequent electrochemical oxidation to form a uniform structure. The filamentous titanium substrate itself possesses good flexibility and mechanical stability, enabling the sensor to maintain stable performance even under bending or dynamic conditions, providing a natural advantage for wearable and portable biosensor applications. The fluorinated electrolyte contains F... - Ions perform localized chemical etching on the oxide layer, and under the induction of an electric field, a highly ordered array of titanium dioxide nanotubes (TNTs) is grown in situ on the surface of the titanium wire, constructing a three-dimensional nanotube array framework. The tubular structure greatly increases the specific surface area of ​​the non-enzymatic glucose sensor.

[0021] S2. The Ti / TiO2 bilayer structure obtained in S1 was placed in a tube furnace and annealed in air. Then, it was heated to 700-900℃ in an argon atmosphere, and a mixed atmosphere of hydrogen and carbon source was introduced. After holding at this temperature for 0.5-2 hours, the gas introduction was stopped, and the temperature was lowered to room temperature in an argon atmosphere to obtain a C / TiO2 / Ti multilayer structure. Hydrogen, as a reducing gas, creates oxygen vacancies on the TiO2 surface, improving its conductivity and introducing active sites. The carbon source decomposes at high temperature, coating the TiO2 nanotubes with a carbon layer. The carbon layer enhances electron transport capability, reduces charge migration impedance, and provides good reaction sites for subsequent loading of metal nanoparticles.

[0022] S3. The C / TiO2 / Ti multilayer structure obtained in S2 is placed in a nickel-containing mixed electrolyte for potentiostatic deposition to obtain a non-enzymatic glucose sensor. 2+ Reduced to metallic nickel, fine and uniformly distributed nickel nanoparticles are deposited on the C / TiO2 / Ti multilayer structure. The reversible redox behavior of Ni provides a highly efficient catalytic center, and the interfacial interaction between Ni and the C / TiO2 / Ti multilayer structure promotes the rapid transfer of electrons from glucose oxidation to the electrode surface.

[0023] In some embodiments of the present invention, in step S1, the titanium wire is cleaned sequentially using ethanol, acetone, and then ethanol. Acetone has a strong dissolving ability and can effectively remove non-polar stains; ethanol is used to remove residual acetone and evaporate quickly, ensuring the titanium wire is clean.

[0024] In some embodiments of the present invention, in S1, the fluorinated electrolyte is a 0.1-0.5M ammonium fluoride solution, the constant voltage for constant voltage deposition is 40-80V, and the constant voltage deposition is carried out at 20-30℃ for 4-8 hours. A voltage is applied to the fluorinated electrolyte, and the titanium wire, acting as the anode, undergoes electrochemical oxidation. - Localized chemical etching of the oxide film was performed, and under the induction of an electric field, a highly ordered TiO2 nanotube array was grown in situ on the surface of the titanium substrate.

[0025] In some embodiments of the present invention, in step S2, the annealing temperature is 500-600°C and the annealing time is 0.5-3 hours. By annealing TNTs in a carbon source (acetylene) and a hydrogen atmosphere, a conductive carbon layer can be generated on their surface, forming carbon-modified TiO2 nanotubes (CTNTs). The introduction of the carbon layer not only significantly improves the overall conductivity of the material, but also modulates the surface electronic structure, introduces defects and oxygen vacancies, and further enhances the electrochemical activity.

[0026] In some embodiments of the present invention, in S2, the carbon source is acetylene. Hydrogen gas can introduce oxygen vacancies on the TiO2 surface, improving its electronic conductivity, and at the same time, it is beneficial to the decomposition of the carbon source. The carbon source forms a thin layer of conductive carbon coating on the surface of the TiO2 nanotube, resulting in a C / TiO2 / Ti multilayer structure.

[0027] In some embodiments of the present invention, in step S3, the nickel-containing mixed electrolyte comprises nickel sulfate and sodium sulfate mixed in a volume ratio of 2-4:1, with the concentration of nickel sulfate being 20-50 mM and the concentration of sodium sulfate being 0.05-0.2 M. Sodium sulfate acts as a supporting electrolyte, improving the conductivity of the nickel-containing mixed electrolyte and stabilizing the deposition process.

[0028] In some embodiments of the present invention, in S3, the voltage for constant potential deposition is -0.5V to -2V, and the deposition time is 100-200s. C-Ni chemical bonds are formed between the nickel particles and the carbon layer, which facilitates the rapid transfer of electrons from the nickel active sites to the three-dimensional porous framework.

[0029] In some embodiments of the present invention, in S3, the constant potential deposition uses a C / TiO2 / Ti multilayer structure as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode.

[0030] In some embodiments of the present invention, the above-described method for preparing a Ni-doped non-enzymatic glucose sensor yields a non-enzymatic glucose sensor.

[0031] The aforementioned Ni-doped non-enzymatic glucose sensor is applied to the detection of glucose in liquids. Nickel nanoparticles efficiently catalyze glucose oxidation under alkaline conditions. In alkaline media, a reversible redox pair of Ni(OH)₂ / NiOOH is formed on the nickel surface, with NiOOH being the main active species for glucose oxidation.

[0032] Example 1 S1. After cleaning, the 7cm titanium wire was allowed to air dry. During cleaning, the titanium wire was sequentially cleaned with ethanol, acetone, and then ethanol. The dried titanium wire was used as the working electrode, and a platinum sheet was used as the counter electrode. Constant voltage deposition was performed in a 0.3M ammonium fluoride solution at a constant voltage of 60V for 5.5h at 25℃ to obtain a Ti / TiO2 bilayer structure.

[0033] S2. The Ti / TiO2 bilayer structure obtained in S1 is placed in a tube furnace and annealed at 550℃ in air for 2 hours. After annealing, the temperature is raised to 800℃ in argon atmosphere, and a mixed atmosphere of hydrogen and acetylene is introduced. After holding at this temperature for 1 hour, the gas supply is stopped, and the temperature is lowered to room temperature in argon atmosphere to obtain a C / TiO2 / Ti multilayer structure.

[0034] S3. The C / TiO2 / Ti multilayer structure obtained in S2 was placed in a mixed electrolyte (40mM nickel sulfate and 0.1M sodium sulfate mixed at a volume ratio of 3:1) for potentiostatic deposition. The C / TiO2 / Ti multilayer structure was used as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The potentiostatic deposition voltage was -1.5V, and the deposition time was 150s, resulting in the non-enzymatic glucose sensor Ni@CTNT.

[0035] Comparative Example S1. After cleaning, the 7cm titanium wire was allowed to air dry. During cleaning, the titanium wire was sequentially cleaned with ethanol, acetone, and then ethanol. The dried titanium wire was used as the working electrode, and a platinum sheet was used as the counter electrode. Constant voltage deposition was performed in a 0.3M ammonium fluoride solution at a constant voltage of 60V for 5.5h at 25℃ to obtain a Ti / TiO2 bilayer structure.

[0036] S2. The Ti / TiO2 bilayer structure obtained in S1 is placed in a tube furnace and annealed at 550℃ in air for 2 hours. After annealing, the temperature is raised to 800℃ in argon atmosphere, and a mixed atmosphere of hydrogen and acetylene is introduced. After holding at this temperature for 1 hour, the gas supply is stopped, and the temperature is lowered to room temperature in argon atmosphere to obtain the C / TiO2 / Ti multilayer structure CTNT.

[0037] Performance testing a. XRD tests were performed on the Ni@CTNT in Example 1 and the CTNT in the comparative example. Figure 1 It can be seen that the CTNT curve is generally flat in the 20°-70° range, with only a wide but not sharp diffuse peak appearing in the 20°-30° range. There are no obvious narrow diffraction peaks, indicating that the overall crystallinity of carbon-modified TiO2 nanotubes is low and the local structure exhibits certain disordered characteristics. This amorphous / low-crystallinity framework is beneficial for providing a larger specific surface area and more exposed active sites, providing abundant anchoring sites for subsequent loading of metallic nickel and its hydroxides.

[0038] Compared to CTNT, Ni@CTNT exhibits a new and distinct diffraction peak at 2θ≈33°, which can be attributed to the (100) crystal plane of hexagonal layered nickel hydroxide Ni(OH)2. Its peak position is essentially consistent with the standard PDF card for Ni(OH)2 (e.g., JCPDS14-0117). Figure 1 The short red lines at the bottom center indicate the positions of several characteristic peaks on the Ni(OH)2 standard card. This result shows that nickel electrodeposited onto the CTNT surface undergoes partial oxidation and hydroxide oxidation in air and alkaline environments, forming a well-crystallized Ni(OH)2 phase. In addition, a weaker, narrow peak can be observed around 44°-46°, possibly related to the (111) crystal plane of a small amount of metallic Ni, but its intensity is significantly lower than the Ni(OH)2 (100) peak at 33°, indicating that Ni(OH)2 is the dominant crystalline phase in Ni@CTNT, while the content of metallic Ni is relatively low.

[0039] In Ni@CTNT, the nickel species are mainly Ni(OH)2, with some trace amounts of Ni, which is consistent with the presence of Ni in XPS analysis. 2+ The valence state distribution is consistent with that of the species. Ni(OH)2 is widely regarded as the precursor phase for the formation of the Ni(OH)2 / NiOOH reversible oxygen-donating pair under alkaline conditions. Therefore, the presence of the Ni(OH)2 crystal phase provides a key active center for the subsequent electrocatalytic oxidation of glucose, and also proves from the crystal structure level that the design of Ni@CTNT electrode material is reasonable and effective.

[0040] b. Raman spectroscopy tests were performed on Ni@CTNT in Example 1 and CTNT in the comparative example, and the results are as follows: Figure 2 As shown, at 1350cm -1 A D peak corresponding to structural defects in carbon materials appears nearby, at 1598 cm⁻¹. -1 left and right corresponding ordered sp 2 G peak of hybrid carbon framework vibration. I peak of CTNT. D / I G The ratio is 0.77, while the I of Ni@CTNT after nickel deposition is... D / I G The ratio significantly increased to 0.99, indicating that electrodeposited nickel introduced more defect sites and altered the degree of order in the carbon framework. D / I G The increased ratio indicates a significant increase in defect density within the three-dimensional framework, suggesting a rise in the proportion of defects and disordered structures. This increase in defects enhances the adsorption capacity of the carbon layer for electrolyte ions and glucose molecules, and also provides more electrochemical active sites. The introduction of nickel, through the formation of C-Ni bonds or perturbation of the local lattice, disrupts the orderliness of the graphitized region, introducing more defect sites into CTNT and providing more potential active centers and electron transport pathways for glucose electrocatalytic reactions.

[0041] c. SEM tests were performed on Ni@CTNT in Example 1 and CTNT in the comparative example, and the results are as follows: Figure 3 and Figure 4 As shown. By Figure 3 As can be seen, the CTNTs in the comparative example have a relatively regular TiO2 nanotube array structure with approximately uniform pore size, clear tube openings, and tight connections between them. The TiO2 nanotube array structure not only significantly increases the specific surface area of ​​the electrode, but also provides a stable and continuous three-dimensional framework for subsequent carbon layer growth and nickel loading, which is beneficial for constructing a highly active, multi-interface electrochemical reaction platform.

[0042] Depend on Figure 4 As can be seen, the original nanotube array structure of Ni@CTNT in Example 1 is still clearly discernible, with its outer surface uniformly covered by a large number of nickel nanoparticles with sizes on the order of tens of nanometers. Some particles bridge each other, forming a continuous point-like conductive network on the surface of the nanotube array. This loading method avoids the obstruction of the channel openings by large metal films, retaining the open and porous characteristics of the nanotube array, which is beneficial for the full wetting of the electrolyte solution and the rapid mass transfer of reactants / products. At the same time, the uniformly distributed nickel nanoparticles significantly increase the available electrocatalytic active sites and shorten the electron transport path through particle-particle and particle-carbon layer contacts, providing a structural basis for the high current response and fast response time exhibited subsequently.

[0043] d. EDS and elemental mapping tests were performed on the Ni@CTNT in Example 1, and the results are as follows: Figure 4 As shown, signals of four elements, Ni, C, Ti and O, were mainly detected in the observed area. The signal distribution of Ni highly overlapped with the morphology of the TiO2 nanotube array, basically covering the tube wall and tube opening. The C element was uniformly coated on the overall framework, corresponding to the carbon modification layer. The distribution of Ti and O outlined the contour of the inner TiO2 substrate.

[0044] e. Perform XPS testing on the Ni@CTNT in Example 1, such as... Figure 5 As shown, characteristic peaks for Ni2p, O1s, Ti2p, and C1s appear at approximately 855 eV, 530 eV, 455 eV, and 285 eV, respectively, in the full spectrum.

[0045] Ti2p 3 / 2 With Ti2p 1 / 2 The peaks are located at approximately 455.18 eV and 461.38 eV, respectively. A slight shift in the Ti2p peak position (to approximately 455 eV) could be attributed to charge transfer effects at the carbon layer and TiO2 interface or differences in energy spectrum calibration. However, the overall trend still indicates that Ti is predominantly TiO2. 4+ It exists in the form of (TiO2). In the fine spectrum of Ni2p, Ni2p can be observed at 856.6 eV and 874.4 eV. 3 / 2 With Ni2p 1 / 2 The main peak, with corresponding satellite peaks at 862.4 eV and 880.25 eV respectively, indicates that nickel exists in both metallic and partially oxidized states (such as Ni). 2+ The coexistence of these multiple valence states facilitates the formation of Ni(OH)2 / NiOOH oxygen-donating pairs in alkaline media, providing active centers for glucose oxidation.

[0046] Analysis of Ni2p, C1s, and O1s components reveals that metallic Ni coexists in Ni@CTNT. 0 with Ni 2+ The species, with carbon layers and TiO2 providing a relatively rich supporting environment of oxygen-containing functional groups and oxygen vacancies. This synergistic structure of multivalent Ni / defect-enriched carbon / TiO2 framework is conducive to the formation of reversible Ni(OH)2 / NiOOH oxygen-donating pairs in alkaline solutions. Metallic Ni provides the nucleation substrate for Ni(OH)2, and surface Ni... 2+ It is more likely to be oxidized to high-valence NiOOH at the working potential, thus participating in the electrocatalytic oxidation process of glucose.

[0047] f. Test the CV curves of Ni@CTNT in Example 1 and CTNT in the comparative example in 0.1M NaOH solution, with and without the addition of 1mM glucose, as follows: Figure 6 As shown in (a), CTNT did not exhibit a significant redox peak in either the presence or absence of glucose, indicating that CTNT in the comparative example has almost no catalytic activity towards glucose. In contrast, the Ni@CTNT electrode showed a clear redox peak in alkaline solution; when glucose was added, the oxidation peak current increased significantly, indicating that Ni@CTNT can effectively catalyze the oxidation of glucose and produce a significant current response.

[0048] Figure 6Figure (b) shows the CV curves of Ni@CTNT in 0.1M NaOH corresponding to different glucose concentrations. As the glucose concentration increases, the oxidation peak current increases monotonically, while the reduction peak changes relatively little, indicating that Ni@CTNT is highly efficient and has a good reproducible response in the catalytic oxidation process of glucose. Figure 6 (c) shows the results at different scan rates (25-125 mV·s) in a 0.1 M NaOH solution containing 1 mM glucose. -1 The CV curves are shown below. It can be seen that as the scan rate increases, the oxidation peak current increases and its position shifts slightly to the positive direction, while the reduction peak current also increases and shifts slightly to the negative direction. A plot of the peak current versus the square root of the scan rate is shown below. Figure 6 In (d) of the figure, it can be seen that the currents of both the oxidation peak and the reduction peak are related to v. 1 / 2 The correlation coefficients showed a good linear relationship, with correlation coefficients of 0.99699 and 0.98964, respectively, indicating that the Ni@CTNT electrode reaction in this system is mainly controlled by the diffusion process.

[0049] g. Ni@CTNT in Example 1 was subjected to iterative testing at voltages of 0.55, 0.58, 0.60, and 0.65V. The results are as follows: Figure 7 As shown in (a), at each potential, continuous droplet addition of 0.5 mM glucose solution at fixed time intervals resulted in a step current response at the moment of addition, confirming the good catalytic response capability of the Ni@CTNT electrode. Under optimized operating potential of 0.60 V and 0.1 M NaOH conditions, it was tested by gradually adding different concentrations of glucose (typical range 0.01-5.78 mM), and the results are as follows: Figure 7 As shown in (b), the current step height gradually increases with increasing glucose concentration, and the current quickly reaches a stable value after each addition. A linear fit is performed between the steady-state response current and the glucose concentration. Figure 7 (c) shows that the current exhibits a good linear relationship with concentration in the range of 0.01-5.78 mM. The current versus time curves after sequentially adding 1 mM glucose, AA (ascorbic acid), UA (uric acid), DA (dopamine hydrochloride), and glucose to 0.1 M NaOH solution are shown in Figure […]. Figure 7 As shown in (d), Ni@CTNT has good anti-interference ability against common interfering substances (AA, UA, DA).

[0050] like Figure 8 As shown in (a), in a 0.1M NaOH solution containing 1mM glucose, the current response time of the Ni@CTNT electrode is less than 2s, demonstrating a rapid kinetic process. Figure 8(b) shows the EIS Nyquist plots of the CTNT and Ni@CTNT samples. The semicircle in the high-frequency region corresponds to the charge transfer resistance (Rct), while the oblique line in the low-frequency region is related to ion diffusion. Calculations show that the Rct of CTNT is approximately 37.49 Ω, while the Rct of Ni@CTNT decreases to approximately 17.23 Ω, indicating that the introduction of nickel significantly improves the charge transfer efficiency at the Ni@CTNT electrode interface.

[0051] To evaluate the consistency of electrode fabrication, five Ni@CTNT electrodes were prepared using the method described in Example 1, and their CV curves were recorded in a 0.1M NaOH solution containing 1mM glucose. The response currents of each electrode are as follows: Figure 8 As shown in (c), the calculated relative standard deviation (RSD) is approximately 3.66%, as... Figure 8 (d) in the middle ( Figure 8 (Partial enlarged view of (c) in the figure) shows that the preparation method has good repeatability and the Ni@CTNT electrode is stable and reliable in batch preparation.

[0052] Therefore, the present invention employs the above-mentioned Ni-doped non-enzymatic glucose sensor, its preparation method and application. The non-enzymatic glucose sensor exhibits rapid and stable response characteristics, a wide linear detection range and a low detection limit in glucose detection, and maintains good stability and repeatability in multiple cycle tests.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for fabricating a Ni-doped non-enzymatic glucose sensor, characterized in that: Includes the following steps: S1. After cleaning the titanium wire, it is naturally dried. The dried titanium wire is used as the working electrode and the platinum sheet is used as the counter electrode. Constant voltage deposition is carried out in a fluorine-containing electrolyte to obtain a Ti / TiO2 bilayer structure. S2. The Ti / TiO2 bilayer structure obtained in S1 is placed in a tube furnace and annealed in an air atmosphere. Then, it is heated to 700-900℃ in an argon atmosphere, and a mixed atmosphere of hydrogen and carbon source is introduced. After holding at this temperature for 0.5-2 hours, the gas inlet is stopped, and the temperature is lowered to room temperature in an argon atmosphere to obtain a C / TiO2 / Ti multilayer structure. S3. The C / TiO2 / Ti multilayer structure obtained in S2 is placed in a nickel-containing mixed electrolyte for constant potential deposition to obtain a non-enzymatic glucose sensor.

2. The method for preparing a Ni-doped non-enzymatic glucose sensor according to claim 1, characterized in that: In S1, the titanium wire is cleaned sequentially with ethanol, acetone, and ethanol.

3. The method for preparing a Ni-doped non-enzymatic glucose sensor according to claim 1, characterized in that: In S1, the fluorinated electrolyte is a 0.1-0.5M ammonium fluoride solution, the constant voltage for constant voltage deposition is 40-80V, and the constant voltage deposition is carried out at 20-30℃ for 4-8 hours.

4. The method for preparing a Ni-doped non-enzymatic glucose sensor according to claim 1, characterized in that: In S2, the annealing temperature is 500-600℃ and the annealing time is 0.5-3h.

5. The method for preparing a Ni-doped non-enzymatic glucose sensor according to claim 1, characterized in that: In S2, the carbon source is acetylene.

6. The method for preparing a Ni-doped non-enzymatic glucose sensor according to claim 1, characterized in that: In S3, the nickel-containing mixed electrolyte includes nickel sulfate and sodium sulfate mixed in a volume ratio of 2-4:1, with the concentration of nickel sulfate being 20-50 mM and the concentration of sodium sulfate being 0.05-0.2 M.

7. The method for preparing a Ni-doped non-enzymatic glucose sensor according to claim 1, characterized in that: In S3, the voltage for constant potential deposition is -0.5V to -2V, and the deposition time is 100-200s.

8. The method for preparing a Ni-doped non-enzymatic glucose sensor according to claim 1, characterized in that: In S3, the potentiostatic deposition uses a C / TiO2 / Ti multilayer structure as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode.

9. A non-enzymatic glucose sensor based on Ni doping, characterized in that: It was prepared using the method for preparing a Ni-doped non-enzymatic glucose sensor as described in any one of claims 1-8.

10. An application of a Ni-doped non-enzymatic glucose sensor, characterized in that: The Ni-doped non-enzymatic glucose sensor of claim 9 is used to detect glucose in liquids.

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