An electrochemical sensor based on cerium vanadate nanorod intercalated MXene composite material and a preparation method and application thereof

Abstract

The application discloses a kind of electrochemical sensor based on cerium vanadate nanorod intercalation MXene composite material and its preparation method and application, belong to electrochemical sensor technical field.The working electrode of the sensor is formed by the composite material modified glassy carbon electrode that cerium vanadate nanorod is uniformly inserted and embedded in MXene interlayer and surface.The preparation method includes: Ti3AlC2 is etched by hydrofluoric acid, and MXene is obtained by ultrasonic stripping;Vanadate nanorod is synthesized by hydrothermal method;Different mass ratios of MXene / CeVO4 material are obtained by ultrasonic-assisted compounding;Electrode is modified by drop coating method.Rutin is detected in phosphate buffer solution with pH=4.0 by differential pulse voltammetry, the linear range is 0.1~11 μmol / L, and the detection limit is 0.052 μmol / L.The sensor has high sensitivity, low detection limit, good reproducibility, stability and anti-interference ability, and can be used for rapid detection of rutin content in drug tablets.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical sensor technology, specifically relating to an electrochemical sensor based on cerium vanadate nanorods intercalated with MXene composite material and its preparation method, as well as the application of the sensor in rutin detection. Background Technology

[0002] Rutin (RT) is a natural flavonoid compound with significant antioxidant, antiviral, antitumor, and anti-inflammatory activities. Medically, rutin is often used as an adjunct treatment for diseases such as diabetes, hypertension, and neuroinflammation. However, excessive consumption of rutin supplements may have adverse effects on human health. Therefore, developing rapid, simple, sensitive, and highly selective methods for rutin detection is of great significance for drug monitoring and food safety control.

[0003] Currently, the main methods for detecting rutin include high-performance liquid chromatography (HPLC), chemiluminescence immunoassay, spectrophotometry, and capillary electrophoresis. While these methods offer a certain level of accuracy, they generally suffer from drawbacks such as expensive equipment, complex operation, long detection times, or insufficient sensitivity. In contrast, electrochemical analysis methods have gained widespread attention in the field of rapid rutin detection due to their significant advantages, including ease of operation, high sensitivity, low detection limits, fast response speed, portable equipment, and lower cost.

[0004] Studies have shown that the electrochemical reaction of rutin on bare glassy carbon electrodes exhibits slow electron transfer kinetics, resulting in weak redox peak currents that are insufficient for high-sensitivity detection. To address this issue, researchers have developed various nanomaterials to modify electrodes, such as reduced graphene oxide, carbon nanotubes, carbon black, and transition metal carbides, to enhance the electrocatalytic activity and electron transport capabilities of the electrodes.

[0005] Transition metal carbides (MXenes) are a novel class of two-dimensional layered materials with the general chemical formula M. n+1 X n T x (M = early transition metal, X = C / N, T) x MXene (containing OH, O, and F) has become a popular material in the field of electrochemical sensing due to its excellent layered structure, high specific surface area, and good conductivity. However, in practical applications, strong van der Waals forces exist between the layers of MXene nanosheets, which easily lead to irreversible stacking and aggregation, resulting in a reduction in effective active area and limited ion transport, thus restricting the full realization of its electrochemical performance. Combining MXene with other functional nanomaterials to construct intercalated or heterostructures is an effective strategy to suppress its stacking and improve its performance.

[0006] Cerium vanadate (CeVO4), a binary transition metal oxide, has good biocompatibility and rich redox properties, but its conductivity is poor when used alone as an electrode material. It usually needs to be combined with highly conductive materials to obtain satisfactory sensing performance.

[0007] Therefore, developing a novel composite material that combines CeVO4 nanorods with MXene sheets, utilizing the "spacer" effect of CeVO4 nanorods to suppress interlayer stacking of MXene, and simultaneously improving electron transport with the highly conductive framework of MXene, is expected to construct a highly sensitive and stable rutin electrochemical sensing platform. Summary of the Invention

[0008] To address the problems of low electrode electrocatalytic activity, insufficient sensitivity, easy stacking and aggregation of MXene materials, and poor conductivity of CeVO4 materials when used alone in existing rutin electrochemical detection methods, this invention provides an electrochemical sensor based on cerium vanadate nanorods intercalated with MXene composite materials, its preparation method, and its application. This is achieved by intercalating CeVO4 nanorods into Ti3C2T... x By constructing a "nanoro-layered" intercalation structure between and on the surface of MXene, the synergistic effect of the two can be used to significantly improve the electron transport capacity and electrocatalytic activity of the electrode, thereby achieving highly sensitive and selective detection of rutin.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: An electrochemical sensor based on cerium vanadate nanorods intercalated with MXene composite material is disclosed. The working electrode of the electrochemical sensor includes a glassy carbon electrode and a modification layer loaded on the surface of the glassy carbon electrode. The modification layer is composed of cerium vanadate nanorods intercalated with MXene composite material. The cerium vanadate nanorods are uniformly distributed in the interlayer and surface of MXene. The mass ratio of cerium vanadate nanorods to MXene in the composite material is any one of 1:1, 1:2, 1:3, 2:1 or 3:1.

[0010] Furthermore, the MXene is Ti3C2T x MXene.

[0011] Furthermore, the modification layer is formed by drop-coating 8 µL of the dispersion of the composite material at a concentration of 1 mg / mL onto the surface of a glassy carbon electrode and then drying it.

[0012] A method for preparing the working electrode of the above-mentioned electrochemical sensor includes the following steps: (1) Ti3C2T xPreparation of MXene: 1.5 g of Ti3AlC2 powder was slowly added to 20 mL of 40% hydrofluoric acid under stirring. The mixture was reacted at room temperature for 24 h. The black precipitate was collected, washed with a 1:1 mixture of distilled water and ethanol, centrifuged until pH 6-7, and then vacuum dried at 60 °C for 12 h. The dried powder was mixed with 15 mL of dimethyl sulfoxide and stirred for 24 h. Excess solvent was removed by centrifugation. The resulting precipitate was dispersed in 100 mL of distilled water and sonicated for 3 h. The product was collected by centrifugation again to obtain Ti3C2T. x MXene; (2) Preparation of cerium vanadate nanorods: 0.1 mol / L cerium nitrate hexahydrate, 0.1 mol / L ammonium vanadate and 0.5 g urea were added to 40 mL of deionized water and stirred continuously for 20 min until dissolved. The resulting solution was transferred to a 100 mL reaction vessel and reacted at 180 °C for 12 h. After the reaction was completed, unreacted substances were removed by washing with ethanol and distilled water alternately. The solid was dried at 60 °C overnight to obtain cerium vanadate nanorods. (3) Preparation of MXene composite material with cerium vanadate nanorods intercalated: Weigh 20 mg of MXene obtained in step (1) and 20 mg of cerium vanadate nanorods obtained in step (2) at a mass ratio of 1:1, add them to a beaker containing 20 mL of deionized water, sonicate for 2 h, then centrifuge with distilled water, and vacuum dry at 60 °C to obtain the composite material; or, weigh the corresponding mass of MXene and cerium vanadate nanorods at a mass ratio of 1:2, 1:3, 2:1 or 3:1 respectively, and prepare composite materials with different mass ratios in the same way; (4) Preparation of working electrode: The composite material obtained in step (3) is dispersed in distilled water, ultrasonically homogenized, and prepared into a dispersion of 1 mg / mL; the glassy carbon electrode is polished to a mirror surface with alumina polishing powder, washed with ultrapure water, and dried; 8 µL of the dispersion is dropped onto the surface of the glassy carbon electrode and dried under an infrared lamp to obtain the working electrode.

[0013] Furthermore, the ultrasonic treatment time in step (3) is 2 hours.

[0014] The above-mentioned electrochemical sensor or the working electrode prepared by the above method was used to detect rutin by differential pulse voltammetry in a 0.1 M phosphate buffer solution with pH=4.0.

[0015] Furthermore, the linear range of the detection is 0.1~11 μmol / L, and the detection limit is 0.052 μmol / L.

[0016] Furthermore, the linear range is divided into two segments: 0.1~3 μmol / L and 3~11 μmol / L.

[0017] Furthermore, when detecting rutin, the electrochemical sensor also has a specific effect on Na... + K + Cl - Uric acid, gallic acid, glucose and ascorbic acid have anti-interference ability. When the concentration of the interfering substance is 800 μmol / L, it has no significant effect on the detection peak current of 80 μmol / L rutin.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. Suppressing MXene interlayer stacking: This invention involves inserting CeVO4 nanorods into Ti3C2T x Nanorods act as spacers between layers and on the surface of MXene, effectively preventing irreversible stacking and aggregation of MXene nanosheets, thereby exposing more electrochemically active sites.

[0019] 2. Enhanced electron transport capability: MXene, as a highly conductive framework, compensates for the poor conductivity of pure CeVO4, promotes rapid electron transfer during electrochemical reactions, and significantly improves the overall conductivity of the composite material.

[0020] 3. Excellent electrocatalytic performance: The synergistic effect between CeVO4 nanorods and MXene significantly enhances the electrocatalytic activity for rutin oxidation. Cyclic voltammetry and impedance spectroscopy tests show that the MXene / CeVO4 / GCE prepared in this invention exhibits higher redox peak currents and lower charge transfer resistance compared to pure MXene, pure CeVO4, and bare GCE.

[0021] 4. High sensitivity and low detection limit: Under optimized conditions, the linear range for detecting rutin by the sensor of this invention is 0.1~11 μmol / L, and the detection limit is as low as 0.052 μmol / L (S / N=3), which is superior to many reported electrochemical sensors for rutin.

[0022] 5. Excellent reproducibility, stability, and anti-interference ability: The relative standard deviation (RSD) for detecting 100 μM rutin using six independently modified electrodes was 4.04%; after 7 days of electrode storage, the peak current still maintained 96.75% of the initial value; for 800 μM Na... + K + Cl - Interfering substances such as uric acid, gallic acid, glucose, and ascorbic acid all showed good anti-interference ability.

[0023] In summary, the sensor of this invention can be used to determine the rutin content in actual pharmaceutical tablets, with a satisfactory recovery rate, indicating that it has good application prospects in the fields of drug monitoring and food safety control. Attached Figure Description

[0024] Figure 1 Scanning electron microscope (SEM) images and elemental mapping diagrams of MXene, CeVO4 and MXene / CeVO4 composite materials prepared for embodiments of the present invention.

[0025] Figure 2 X-ray diffraction (XRD), Fourier transform infrared absorption spectrum (FT-IR), and X-ray photoelectron spectroscopy (XPS) of Ti3AlC2, MXene, CeVO4, and MXene / CeVO4 composite materials prepared for embodiments of the present invention.

[0026] Figure 3 The high-resolution XPS spectrum of the MXene / CeVO4 composite material prepared in the embodiments of the present invention is shown, wherein (A) C1s, (B) Ti 2p, (C) Ce 3d, and (D) V 2p.

[0027] Figure 4 Bare GCE, MXene / GCE, CeVO4 / GCE, and MXene / CeVO4 / GCE were prepared in the presence of 0.1 M KCl and 1.0 mM [Fe(CN)6]. 3- / 4- Cyclic voltammetry curves in solution.

[0028] Figure 5 Bare GCE, MXene / GCE, CeVO4 / GCE, and MXene / CeVO4 / GCE were prepared in the presence of 0.1 M KCl and 5.0 mM [Fe(CN)6]. 3- / 4- Electrochemical impedance spectroscopy in solution.

[0029] Figure 6 The differential pulse voltammograms show the detection of 80 μM rutin by the electrochemical sensor of the present invention in 0.1 M PBS buffer at different pH values ​​(3.0, 4.0, 5.0, 6.0, 7.0).

[0030] Figure 7 Differential pulse voltammograms (A) and corresponding peak current histograms (B) of the electrochemical sensor of this invention for detecting 80 μM rutin using MXene / CeVO4 composite modified electrodes with different mass ratios (1:1, 1:2, 1:3, 2:1, 3:1) in 0.1 M PBS buffer at pH=4.0 are shown.

[0031] Figure 8The figure shows the cyclic voltammetry curves of the electrochemical sensor of the present invention detecting 80 μM rutin at different scan rates (120, 140, 160, 180, 200, 220, 240 mV / s) in 0.1 M PBS buffer at pH=4.0.

[0032] Figure 9 This is a differential pulse voltammogram of the electrochemical sensor of the present invention under optimized conditions for detecting different concentrations of rutin (0.1, 0.3, 0.5, 0.8, 1, 3, 5, 7, 9, 11 μmol / L).

[0033] Figure 10 for Figure 9 Linear relationship between peak oxidation current and rutin concentration.

[0034] Figure 11 The peak current histogram (reproducibility test) of the electrochemical sensor of the present invention, obtained by detecting rutin with six independently prepared modified electrodes in 0.1 M PBS buffer containing 100 μM rutin at pH 4.0, is shown.

[0035] Figure 12 The electrochemical sensor of this invention was stored in 0.1 M PBS buffer containing 100 μM rutin at pH 4.0 for 7 days, and the peak current changes of the same concentration of rutin were detected daily (stability test).

[0036] Figure 13 To prepare the electrochemical sensor of this invention, 800 μM of various interfering substances (Na+) were added to a 0.1 M PBS buffer containing 80 μM rutin at pH 4.0. + K + Cl - Differential pulse voltammogram after uric acid, gallic acid, glucose, and ascorbic acid. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. All technical solutions implemented based on the content of this invention fall within the scope of protection claimed by this invention. Example

[0038] I. Material Preparation 1. Ti3C2T x Preparation of MXene Ti3C2T x The preparation of MXene followed the methods described in existing literature. The specific steps are as follows: 1.5 g of Ti3AlC2 powder was slowly added to 20 mL of 40% hydrofluoric acid under stirring, and the reaction was carried out at room temperature for 24 h. After the reaction was completed, the black precipitate was collected, washed with a 1:1 mixture of distilled water and ethanol, centrifuged until pH 6-7, and then dried under vacuum at 60 °C for 12 h.

[0039] To further remove the precipitate, the dried powder was mixed with 15 mL of dimethyl sulfoxide (DMSO) and stirred for 24 h. Excess solvent was removed by centrifugation. The resulting precipitate was dispersed in 100 mL of distilled water and sonicated for 3 h. The product was then collected by centrifugation to obtain Ti3C2T. x MXene.

[0040] 2. Preparation of cerium vanadate (CeVO4) nanorods 0.1 mol / L cerium nitrate hexahydrate, 0.1 mol / L ammonium vanadate, and 0.5 g urea were added to 40 mL of deionized water and stirred continuously for 20 min until completely dissolved. The resulting solution was transferred to a 100 mL reaction vessel and reacted at 180 °C for 12 h. After the reaction was complete, unreacted substances were removed by washing with ethanol and distilled water alternately. The solid was dried overnight at 60 °C to obtain brown powdery CeVO4 nanorods.

[0041] 3. Preparation of MXene / CeVO4 composite materials Weigh 20 mg of MXene and 20 mg of CeVO4 nanorods prepared in the above steps at a mass ratio of 1:1, add them to a beaker containing 20 mL of deionized water, and synthesize them using an ultrasonic-assisted method. After ultrasonic treatment for 2 h, centrifuge with distilled water and vacuum dry at 60 °C to obtain the MXene / CeVO4 composite material.

[0042] Following the same steps, MXene and CeVO4 nanorods of corresponding masses were weighed at mass ratios of 1:2, 1:3, 2:1, and 3:1 to prepare composite materials with different mass ratios, which were then stored at 4°C for later use.

[0043] II. Preparation of the working electrode 1. Pretreatment of glassy carbon electrode The glassy carbon electrode (GCE) was polished to a mirror finish on suede using 50 nm alumina polishing powder, washed with ultrapure water, and then dried in a nitrogen stream for 30 min to obtain the pretreated glassy carbon electrode.

[0044] 2. Fabrication of the MXene / CeVO4 / GCE working electrode The MXene / CeVO4 composite material prepared above was dispersed in distilled water and sonicated to prepare a 1 mg / mL dispersion. 8 µL of this dispersion was drop-coated onto the surface of a pretreated glassy carbon electrode and dried under an infrared lamp to obtain the MXene / CeVO4 / GCE working electrode.

[0045] 3. Preparation of the control working electrode (1) MXene / GCE working electrode: MXene was dispersed in distilled water and sonicated to prepare a dispersion of 1 mg / mL. 8 µL of the dispersion was dropped onto the surface of the pretreated glassy carbon electrode and dried under an infrared lamp to obtain the MXene / GCE working electrode.

[0046] (2) CeVO4 / GCE working electrode: CeVO4 nanorods were dispersed in distilled water and sonicated to prepare a dispersion of 1 mg / mL. 8 µL of the dispersion was drop-coated onto the surface of the pretreated glassy carbon electrode and dried under an infrared lamp to obtain the CeVO4 / GCE working electrode.

[0047] (3) Bare GCE: The glassy carbon electrode after pretreatment is used directly, which is called bare GCE.

[0048] III. Electrochemical Testing Methods Electrochemical measurements were performed using a three-electrode system: the prepared working electrode was used as the working electrode, the saturated calomel electrode (SCE) as the reference electrode, and the platinum wire electrode as the counter electrode. Cyclic voltammetry (CV) tests were conducted in a solution containing 0.1 M KCl and 1.0 mM [Fe(CN)6]. 3- / 4- The measurements were performed in a buffer solution containing 0.1 mM KCl and 5.0 mM [Fe(CN)6] at a scan rate of 50 mV / s. 3- / 4- The tests were performed in a buffer solution with a frequency range of 0.01 Hz to 100 kHz and an amplitude of 5 mV. Differential pulse voltammetry (DPV) tests were performed in 0.1 M PBS buffer for the detection of rutin and evaluation of its various properties.

[0049] IV. Performance Test Results 1. Morphological characteristics like Figure 1 The image shows the morphological characteristics of MXene, CeVO4, and MXene / CeVO4. From... Figure 1 As can be seen in A, MXene obtained through the HF etching process has a multi-layered structure resembling an accordion. Figure 1 B and C show that CeVO4 exists in an aggregated state, and a nanorod-like structure was observed at 200 nm. Figure 1As shown in Figure D, the composite structure of MXene and CeVO4 is such that cerium vanadate nanorods are uniformly loaded on the surface and between the layers of MXene. Figure 1 EJ showed the corresponding elemental mapping image of MXene / CeVO4, from which the uniform distribution of C, F, Ti, O, Ce and V was clearly observed, which initially proved the successful preparation of the material.

[0050] 2. XRD, FT-IR, and XPS full spectra of different materials The Ti3AlC2 and Ti3C2T were studied by XRD. x Crystallization properties of MXene, CeVO4, and MXene / CeVO4. For example... Figure 2 As shown in Figure A, after HF acid etching, the (104) characteristic diffraction peak of MXene disappeared, indicating that the original Ti3AlC2 crystal structure had been successfully exfoliated. The removal of the Al atomic layers transformed the material into a multilayer MXene structure. Ti3C2T x The diffraction peaks of (002), (004), and (110) are located at 2θ = 5.9°, 17.86°, and 60.8°, respectively, proving that Ti3C2T has been synthesized. x MXene. In Ti3AlC2, the (002) crystal plane showed a significant left shift after etching and dimethyl sulfoxide (DMSO) intercalation. Specifically, it shifted 3.6° to the left from 9.5° to 5.9°, possibly due to the increased interlayer spacing of MXene after intercalation, leading to the leftward shift of the (002) diffraction peak. For CeVO4, the X-ray diffraction pattern showed diffraction peaks at 18.6°, 23.92°, 32.24°, and 47.72°. Figure 2 B), corresponding to its (101), (200), (112), and (312) crystal planes, indicates the successful preparation of cerium vanadate nanoparticles. X-ray diffraction peaks of the MXene / CeVO4 composite material revealed that after CeVO4 modification, the diffraction peak corresponding to its (002) crystal plane shifted 0.54° to the left from 5.9° to 5.36°, indicating a slight increase in the interlayer spacing of MXene. Figure 2 The XRD analysis of the composite in B shows that the main diffraction peaks of each material are retained, indicating the successful preparation of the composite material. Figure 2 C shows the FT-IR spectra of MXene, CeVO4, and the MXene / CeVO4 complex; all materials are within the range of 3442 cm⁻¹. -1 A broad and strong absorption band is observed nearby, attributed to the stretching vibration of OH. For MXene, at 1633 cm⁻¹... -1 1400cm -1 1049cm -1 453cm -1The specific absorption peak at 804 cm⁻¹ is attributed to the stretching of C=O, OH, CF, and Ti-C, demonstrating the successful etching of MXene. The spectrum of CeVO₄ at 804 cm⁻¹... -1 and 451cm -1 This is due to the stretching effect of Ce-O and VO. The presence of absorption peaks for all substances in the infrared spectrum of the composite sample indicates that CeVO4 modification of MXene was successful. Figure 2 The five peaks of C1s, O1s, Ti2p, Ce3d, and V2p in the full XPS spectrum of D reveal the presence of C, O, Ti, Ce, and V in the MXene / CeVO4 composite material, indicating the successful preparation of the material.

[0051] 3. XPS testing of composite materials XPS analysis of the MXene / CeVO4 composite element composition revealed the presence of Ce, V, Ti, and C elements through Ce3d, V2p, Ti2p, and C1s. Figure 3 As shown in Figure A, the four energy peaks at 284.2, 285.5, 287.1, and 291.7 eV correspond to C-Ti, CC, CO, and C=O, respectively. The high-resolution bimodal spectrum of Ti2p reveals the Ti2p... 3 / 2 and Ti2p 1 / 2 Two strong peaks ( Figure 3 B), located at binding energies of 457.3 eV and 463.6 eV, respectively. Figure 3 In C, XPS spectra of Ce3d with different binding energies are shown at 881.3 eV, 885.1 eV, 899.8 eV, and 904.3 eV, indicating the presence of Ce. 3+ The oxidation state of Ce3d. The peaks at binding energies of 881.0 eV and 885.1 eV correspond to Ce3d. 5 / 2 The peaks at binding energies of 899.2 eV and 904.6 eV correspond to Ce3d... 3 / 2 . Figure 3 In D, V 2p 3 / 2 and V2p 1 / 2 The peaks correspond to band energies of 516.0 eV and 523.4 eV. These results further demonstrate the successful preparation of MXene / CeVO4.

[0052] 4. Cyclic Voltmeter-Ampere Test Bare GCE, MXene / GCE, CeVO4 / GCE, and MXene / CeVO4 / GCE were used as working electrodes in a solution containing 0.1 M KCl and 1.0 mM [Fe(CN)6]. 3- / 4- The CV test was performed in the buffer solution, and the results are as follows: Figure 4 As shown. From Figure 4As can be seen, the CV curves of each electrode all exhibit a pair of distinct redox peaks. Among them, the bare GCE has the lowest peak current and the worst conductivity. Compared with bare GCE, CeVO4 / GCE, and MXene / GCE, MXene / CeVO4 / GCE has the highest redox peak current. This result indicates that CeVO4 nanorods combined with MXene were successfully modified onto the electrode surface, and the synergistic effect of the composite material significantly enhanced the electron transfer capability of the electrode.

[0053] 5. Electrochemical impedance spectroscopy (EIS) The above four electrodes were placed in a solution containing 0.1 M KCl and 5.0 mM [Fe(CN)6]. 3- / 4- EIS testing was performed in the buffer solution, and the results are as follows: Figure 5 As shown. In the high-frequency region of EIS, a larger semicircle diameter indicates a larger charge transfer resistance (Rct). From Figure 5 It can be seen that the GCE modified with MXene / CeVO4 nanocomposite has the smallest semi-circular region and the smallest Rct value. This result indicates that the introduction of CeVO4 nanorods can effectively promote the electron transfer activity of the composite. The EIS results are consistent with the CV results, further demonstrating that the MXene / CeVO4 composite can significantly enhance the electron transfer capability.

[0054] 6. pH optimization The current response of the electrochemical sensor of this invention to rutin was investigated using DPV technology in 0.1 M PBS buffer at different pH values ​​(3.0, 4.0, 5.0, 6.0, 7.0). The results are as follows: Figure 6 As shown in the figure. The results indicate that pH value has a significant impact on the current response and peak potential; the sensor exhibits the largest current response to rutin at pH=4.0. Therefore, 0.1M PBS buffer at pH=4.0 was selected as the optimal detection medium.

[0055] 7. Proportion Optimization The response of different ratios of MXene:CeVO4 to rutin was tested in 0.1 M PBS buffer at pH 4.0. Figure 7 Figures A and B show the DPV curves and broken-line graphs of MXene:CeVO4 at different mass ratios in PBS solution at pH 4. It can be seen that as the mass of CeVO4 increases, the peak current in response to rutin gradually decreases. This may be because excess CeVO4 tends to aggregate, leading to a decrease in electron transport performance and a reduction in active sites. Simultaneously, the peak current shows the same trend when the mass of MXene increases. The results indicate that the highest response signal to rutin is observed when the MXene:CeVO4 mass ratio is 1:1; therefore, a 1:1 mass ratio electrode was used for subsequent tests.

[0056] 8. The effect of scan rate In 0.1 M PBS buffer at pH 4.0, with a fixed rutin concentration of 80 μM, CV tests were performed at different scan rates (120, 140, 160, 180, 200, 220, 240 mV / s). The results are as follows. Figure 8 As shown. From Figure 8 It can be seen that as the scan rate increases, the redox peak current gradually increases and the oxidation peak potential shifts positively, indicating that the electrochemical reaction of rutin on the MXene / CeVO4 / GCE electrode is an irreversible redox process.

[0057] 9. Linear range and detection limit Under optimized conditions (0.1 M PBS buffer at pH 4.0), the current response of the electrochemical sensor of this invention to different concentrations of rutin was investigated using DPV technology. The rutin concentrations were 0.1, 0.3, 0.5, 0.8, 1, 3, 5, 7, 9, and 11 μmol / L, respectively. The results are as follows: Figure 9 As shown, the peak oxidation current gradually increases with increasing rutin concentration.

[0058] like Figure 10 As shown, the oxidation peak current exhibits two linear relationships with rutin concentration in the range of 0.1–11 μmol / L: good linearity is observed in the concentration ranges of 0.1–3 μmol / L and 3–11 μmol / L, respectively. In the lower concentration range, the slope of the calibration curve is higher due to the presence of numerous active sites; in the higher concentration range, the slope of the calibration curve decreases due to the gradual saturation of active sites.

[0059] According to the detection limit calculation formula LOD = 3σ / K (where σ is the standard deviation of 10 parallel blank samples and K is the slope of the standard curve), the detection limit of the MXene / CeVO4 / GCE sensor of the present invention for rutin is calculated to be 0.052 μmol / L (S / N=3).

[0060] As shown in Table 1, the prepared sensor has relatively high detection performance compared with the previously reported Rutin electrochemical sensing.

[0061] Table 1. Comparison of detection performance between the electrochemical sensor of this invention and reported rutin electrochemical sensors. In the table: [1] Wang Y, Chen J, Wang C, et al. An electrochemical sensor basedonCe-MOF-derived Ce-doped poly (3, 4-ethylenedioxythiophene) composite forefficient determination of rutin in food[J]. Talanta, 2023, 263: 124678. [2]Ramadoss J, Govindasamy M, Sonachalam A, et al. CuMoO4 / Ti3C2Txnanocomposite layers perform as an ultrasensitive electrochemicalsensor for the detection of antioxidant rutin[J]. Microchimica Acta, 2024,191(4): 226. [3]Gu H, Shui X, Zhang Y, et al. Porous carbon scaffolded Fe-basedalloynanoparticles for electrochemical quantification of acetaminophen andrutin[J].Carbon, 2024, 221: 118954. [4]Shobana B, Prakash P. Sensitive rutin detection at nanomolarlevelsutilizing CeO2 / BaO@ Ti3C2Tx nanocomposite-based photoelectrochemicalsensor[J].Materials Science in Semiconductor Processing, 2025, 186: 109035. [5]Song XY, Meng X, Xiao BL, et al. MWCNTs-CTAB and HFs-Lacnanocomposite-modified glassy carbon electrode for rutin determination[J]. Biosensors, 2022, 12(8): 632. [6] Moulya KP, Manjunatha JG, Nagarajappa H, et al. Electrochemicallypolymerized dopamine activated carbon paste sensor for selective and sensitive detection of rutin in the presence of riboflavin[J]. Microchemical Journal, 2024, 201: 110561. 10. Reproducibility Testing Six glassy carbon electrodes were used, and six MXene / CeVO4 / GCE working electrodes were prepared according to the aforementioned method. These six working electrodes were then used as the working electrodes of the electrochemical sensor of this invention. DPV tests were performed in 0.1 M PBS buffer containing 100 μM rutin at pH 4.0, and the oxidation peak current of each electrode was recorded. The results are as follows: Figure 11 As shown in the figure. The results indicate that the peak current variation for detecting the same concentration of rutin using six independently modified electrodes is small, with a relative standard deviation (RSD) of 4.04%, demonstrating that the electrochemical sensor based on the MXene / CeVO4 composite material has good reproducibility.

[0062] 11. Stability Testing The MXene / CeVO4 / GCE working electrode was stored at 4°C for 7 days. Each day, it was removed and subjected to DPV testing in 0.1 M PBS buffer containing 100 μM rutin (pH 4.0). The oxidation peak current was recorded, and the results are as follows: Figure 12 As shown in the figure. The results indicate that after 7 days of storage, the peak current of the sensor can still maintain 96.75% of the initial value, indicating that the electrochemical sensor based on MXene / CeVO4 composite material has good long-term stability.

[0063] 12. Anti-interference capability test In a 0.1 M PBS buffer containing 80 μM rutin and pH=4.0, 800 μM Na+ was added.+ K + Cl - Uric acid, gallic acid, glucose, and ascorbic acid were used as interfering agents. The changes in peak current were detected using DPV technology, and the results are as follows: Figure 13 As shown in the figure. The results indicate that the presence of the aforementioned interfering substances has almost no effect on the peak current of rutin detection, demonstrating that the electrochemical sensor based on the MXene / CeVO4 composite material has good anti-interference ability against rutin.

[0064] In summary, the electrochemical sensor based on cerium vanadate nanorods intercalated with MXene composite material constructed in this invention exhibits excellent analytical performance for rutin, with advantages such as high sensitivity, low detection limit, good reproducibility, strong stability, and strong anti-interference ability. It has good application prospects in the fields of drug monitoring and food safety control.

Claims

1. An electrochemical sensor based on cerium vanadate nanorods intercalated with MXene composite material, characterized in that, The working electrode of the electrochemical sensor includes a glassy carbon electrode and a modification layer loaded on the surface of the glassy carbon electrode. The modification layer is composed of a cerium vanadate nanorod intercalated with MXene composite material. The cerium vanadate nanorods are uniformly distributed in the interlayer and surface of MXene. The mass ratio of cerium vanadate nanorods to MXene in the composite material is any one of 1:1, 1:2, 1:3, 2:1 or 3:

1.

2. The electrochemical sensor according to claim 1, characterized in that, The MXene is Ti3C2T x MXene.

3. The electrochemical sensor according to claim 1, characterized in that, The modification layer is formed by drop-coating 8 µL of the dispersion of the composite material at a concentration of 1 mg / mL onto the surface of a glassy carbon electrode and then drying it.

4. A method for preparing the working electrode of the electrochemical sensor according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Ti3C2T x Preparation of MXene: 1.5 g of Ti3AlC2 powder was slowly added to 20 mL of 40% hydrofluoric acid under stirring. The mixture was reacted at room temperature for 24 h. The black precipitate was collected, washed with a 1:1 mixture of distilled water and ethanol, centrifuged until pH 6-7, and then vacuum dried at 60 °C for 12 h. The dried powder was mixed with 15 mL of dimethyl sulfoxide and stirred for 24 h. Excess solvent was removed by centrifugation. The resulting precipitate was dispersed in 100 mL of distilled water and sonicated for 3 h. The product was collected by centrifugation again to obtain Ti3C2T. x MXene; (2) Preparation of cerium vanadate nanorods: 0.1 mol / L cerium nitrate hexahydrate, 0.1 mol / L ammonium vanadate and 0.5 g urea were added to 40 mL of deionized water and stirred continuously for 20 min until dissolved. The resulting solution was transferred to a 100 mL reaction vessel and reacted at 180 °C for 12 h. After the reaction was completed, unreacted substances were removed by washing with ethanol and distilled water alternately. The solid was dried at 60 °C overnight to obtain cerium vanadate nanorods. (3) Preparation of MXene composite material with cerium vanadate nanorods intercalated: Weigh 20 mg of MXene obtained in step (1) and 20 mg of cerium vanadate nanorods obtained in step (2) at a mass ratio of 1:1, add them to a beaker containing 20 mL of deionized water, sonicate for 2 h, then centrifuge with distilled water, and vacuum dry at 60 °C to obtain the composite material; or, weigh the corresponding mass of MXene and cerium vanadate nanorods at a mass ratio of 1:2, 1:3, 2:1 or 3:1 respectively, and prepare composite materials with different mass ratios in the same way; (4) Preparation of working electrode: Disperse the composite material obtained in step (3) in distilled water, sonicate it evenly, and prepare a dispersion of 1 mg / mL; polish the glassy carbon electrode to a mirror surface with alumina polishing powder, wash it with ultrapure water and dry it; take 8 µL of the dispersion and drop it onto the surface of the glassy carbon electrode, and bake it dry under an infrared lamp to obtain the working electrode.

5. The method according to claim 4, characterized in that, The ultrasonic treatment in step (3) takes 2 hours.

6. The application of the electrochemical sensor according to any one of claims 1 to 3 or the working electrode prepared by the method of claim 4 or 5 in the detection of rutin, characterized in that, The differential pulse voltammetry method was used to detect the substance in a 0.1 M phosphate buffer solution at pH 4.

0.

7. The application according to claim 6, characterized in that, The linear range of the detection is 0.1~11 μmol / L, and the detection limit is 0.052 μmol / L.

8. The application according to claim 7, characterized in that, The linear range is divided into two segments: 0.1~3 μmol / L and 3~11 μmol / L.

9. The application according to claim 6, characterized in that, The electrochemical sensor, when detecting rutin, has a certain effect on Na. + K + Cl - Uric acid, gallic acid, glucose and ascorbic acid have anti-interference ability. When the concentration of the interfering substance is 800 μmol / L, it has no significant effect on the detection peak current of 80 μmol / L rutin.

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