NiOOH@NiFe-pba modified carbon cloth self-supporting electrode, preparation method and detection application thereof

Abstract

The application discloses a kind of NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode and its preparation method and the application of simultaneous detection of dopamine and uric acid.I.e., nickel molybdate nanorod is first synthesized in situ on carbon cloth, then etched and electrochemically restructured by ion exchange method in sequence to prepare NiOOH@NiFe-PBA / CC self-supporting electrode, wherein the nanorod presents internal hollow and surface rough structure morphology;Therefore, the electrode has greater active specific surface area, more active sites, more unobstructed mass transfer channel, and increased surface oxygen-containing groups and greater surface hydrophilicity surface.The self-supporting electrode disclosed in the application realizes high-sensitivity and high-selectivity simultaneous detection of dopamine and uric acid, with the advantages of wide detection linear range, low detection limit, good stability, high sensitivity and strong anti-interference ability, wherein the detection linear range of dopamine is 0.05-20 μmol / L, and the detection limit is 4.7 nmol / L;The detection linear range of uric acid is 5-55 μmol / L, and the detection limit is 28.53 nmol / L.

Description

TECHNICAL FIELD

[0001] The present application relates to a NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode, and also relates to a preparation method of the electrode, and an application of a chemical sensing platform based on the electrode for simultaneously detecting dopamine and uric acid. BACKGROUND

[0002] Dopamine (DA) and uric acid (UA) are two important biomolecules in the human body. As a key neurotransmitter, DA (normal concentration range 0.01 ~ 1 μmol·L -1 ) participates in the regulation of mood, motor control and other physiological processes, and its abnormal content may cause Parkinson's disease and other neurological diseases. UA, as the end product of purine metabolism, plays an important role in maintaining blood pressure and antioxidant activity, but its abnormal level can cause gout and other diseases. The commonly used detection methods include high performance liquid chromatography-mass spectrometry, fluorescence method, spectrophotometry, etc., but these methods are complex, expensive and time-consuming, and require special instruments. Electrochemical methods are more suitable for clinical detection due to their simple operation, rapid response and good selectivity. However, DA and UA have similar structures and close oxidation potentials, and their electrochemical signals are easily interfered with each other, so simultaneous high-sensitivity electrochemical detection of DA and UA faces great challenges. Therefore, it is very important to develop an advanced electrode modification material to improve its sensitivity and selectivity.

[0003] Metal-organic frameworks (MOFs) are porous crystalline materials formed by metal nodes and organic ligands through coordination. This kind of material has the characteristics of structure designable, large specific surface area and precise adjustable pore size, and is widely used in gas adsorption, catalytic reaction, sensor device and energy storage. Prussian blue analogues (PBAs) are typical MOFs materials, whose molecular structure is composed of octahedrons formed by two kinds of metal atoms bridged by cyanide ligands, i.e. hexacyanometalate, which maintains the characteristic of carbon-nitrogen triple bond structure, and its key properties such as conductivity and stability can be controlled by replacing different metal species. Due to its unique three-dimensional open metal framework and pore structure, rich redox active sites and high specific surface area, it has shown wide application prospects in electrocatalysis, electrochemical sensing, battery materials and other fields.

[0004] The present application aims at the problems of limited linear range and insufficient response sensitivity of existing detection technology. After synthesizing nickel molybdate nanorod precursor on carbon cloth, NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode is prepared by ion exchange and electrochemical reconstruction in turn. In the process of potassium ferricyanide etching, nickel ions in the nanorod migrate to the surface to form NiFe-PBA, and a hollow nanorod structure is formed at the same time; in the process of electrochemical reconstruction, by applying a cyclic potential, Ni²⁺ is partially oxidized to Ni³⁺ / Ni 4 ⁺, forming NiOOH species. The whole process not only introduces a large number of oxygen-containing functional groups (such as hydroxyl, oxygen vacancy, etc.) on the surface of the material, greatly improving the surface hydrophilicity of the material, but also leads to the rearrangement of the internal structure of the material, greatly increasing the specific surface area and exposing more edge active sites. The oxygen vacancies and functional groups on the surface of NiOOH@NiFe-PBA can significantly enhance the adsorption capacity of the analytes DA and UA, and improve the electrochemical sensing performance. The NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode can provide larger electroactive area, rich catalytic active center and functional groups, thereby ensuring efficient capture of analytes and significantly improving the sensitivity and selectivity of electrochemical detection of DA and UA. Therefore, based on the NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode, high-sensitivity and high-selectivity electrochemical detection of DA and UA can be realized. SUMMARY

[0005] A NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode, characterized in that the self-supporting electrode is composed of carbon cloth and NiOOH@NiFe-PBA heterostructure grown in situ on the surface of the carbon cloth; the NiOOH@NiFe-PBA heterostructure is obtained by etching nickel molybdate nanorods grown in situ on the carbon cloth with K3[Fe(CN)6] and then electrochemically activating under alkaline conditions by cyclic voltammetry; the carbon cloth is denoted as CC; the nickel molybdate nanorods grown in situ on the carbon cloth are denoted as NiMoO4 / CC; the electrode after K3[Fe(CN)6] etching is denoted as NiFe-PBA@NiMoO4 / CC; the NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode is denoted as NiOOH@NiFe-PBA / CC;

[0006] A preparation method of the carbon cloth self-supporting electrode, characterized in that it comprises the following steps:

[0007] (a) Preparation of NiMoO4 / CC

[0008] Cut CC into a size of 2 cm x 3 cm, and sequentially wash it in anhydrous ethanol and deionized water for 15 min, and then place it in a 15 mmol·L-1 Na2MoO4 solution containing 30 mL of deionized water.-1 The dilute nitric acid was heated in a reaction kettle at 120℃ for 3h, and after cooling and washing, it was transferred into a 50 mL reaction kettle, 2 mmol Ni(NO3)2·6H2O, 0.5 mmol (NH4)6Mo7O 24 4H2O and 25 mL deionized water were added, and after uniform mixing, it was reacted at 150℃ for 6h, and after cooling, it was washed and dried to obtain a NiMoO4 / CC electrode;

[0009] (b) Preparation of NiFe-PBA@NiMoO4 / CC

[0010] The NiMoO4 / CC prepared in step (a) was placed in a 20 ml solution containing 0.4-1.0 mmol K3[Fe(CN)6], and reacted in an oil bath at 90℃ for 30-240 min, and after washing and drying, a NiFe-PBA@NiMoO4 / CC electrode was obtained;

[0011] (c) Preparation of NiOOH@NiFe-PBA / CC

[0012] The NiFe-PBA@NiMoO4 / CC prepared in step (b) was used as the working electrode, a graphite rod was used as the counter electrode, mercury / metal oxide was used as the reference electrode, and 1 mol·L -1 -1 KOH was used as the electrolyte, and in the three-electrode system, a cyclic voltammetry method was used for electrochemical reconstruction to obtain a NiOOH@NiFe-PBA / CC electrode;

[0013] The scan rate of the cyclic voltammetry method used in step (c) of the preparation method was 100 mV·s -1 , the scan potential window was 0 to 1 V, and the scan number was 20-60; the nanorods of the obtained NiOOH@NiFe-PBA / CC catalyst exhibited a hollow structure, the surface roughness increased significantly, the surface oxygen-containing groups increased, and the contact angle decreased significantly, showing enhanced surface hydrophilicity.

[0014] The third object of the present application is to provide a NiOOH@NiFe-PBA / CC electrode for simultaneously detecting dopamine and uric acid, characterized in that 0.1 mol / L pH 6.5 phosphate buffer is used as a supporting electrolyte, an electrolyte solution containing different concentrations of DA and UA single or mixed is added to an electrolytic cell, a NiOOH@NiFe-PBA / CC electrode is used as a working electrode, a differential pulse voltammetry (DPV) method is used for detection, linear regression equations of the oxidation peak current of DA and UA and their concentrations are obtained respectively, the oxidation peak current of DA and UA in the sample to be measured is determined by the same method, and the content of DA and UA in the sample is calculated by substituting the linear regression equation.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (a) The NiOOH@NiFe-PBA / CC electrode of the present invention has a large number of oxygen-containing functional groups (such as hydroxyl groups, oxygen vacancies, etc.) on its surface, which greatly improves the surface hydrophilicity of the material and presents a hollow nanorod structure, which significantly enhances the adsorption capacity of analytes DA and UA, and greatly improves the sensitivity and selectivity of electrochemical simultaneous detection of DA and UA.

[0017] (b) The NiOOH@NiFe-PBA / CC electrode exhibited a wide linear range (0.05–20 μmol / L), a low detection limit (4.7 nmol / L, S / N=3), and high sensitivity (471.3 μA·μM⁻¹·cm⁻²) for DA detection; similarly, it achieved a wide linear range (5–55 μmol / L), a low detection limit (28.53 nmol / L, S / N=3), and high sensitivity (117.76 μA·μM⁻¹·cm⁻²) for UA detection. In the presence of both DA and UA, it demonstrated good selectivity, anti-interference ability, and stability, effectively distinguishing their oxidation peaks and avoiding mutual interference. Attached Figure Description

[0018] Figure 1 The images are SEM images of NiMoO4 / CC (a, d), NiFe-PBA@NiMoO4 / CC (b, e), and NiOOH@NiFe-PBA / CC (c, f) corresponding to Comparative Examples 2, 3, and 1, respectively.

[0019] Figure 2 The figures represent CC (a), NiMoO4 / CC (b), NiFe-PBA@NiMoO4 / CC (c), and NiOOH@NiFe-PBA / CC (d) corresponding to Comparative Examples 1, 2, 3, and 1, respectively, in a solution containing 0.1 mol L... −1 5.0 mmol L of KCl −1 [Fe(CN)6] 3− / 4− 0.1 mol·L -1 CV diagram (left) and electrochemical impedance diagram (right) of KCl solution.

[0020] Figure 3 The CV diagrams are for different amounts of potassium ferricyanide in 20 mL solutions of Examples 1, 2 and 3 during the ion exchange step, namely 0.6 mmol K3[Fe(CN)6] (a), 0.1 mmol K3[Fe(CN)6] (b), and 1.0 mmol K3[Fe(CN)6] (c).

[0021] Figure 4 The CV plots are for Examples 1, 4 and 5, respectively, showing the time taken to maintain the product in an oil bath at 90°C for 120 min (a), 60 min (b) and 240 min (c).

[0022] Figure 5 CV plots for electrochemical reconstruction at 20 (a), 40 (b), and 60 (c) cycles for Examples 1, 6, and 7. This indicates that the optimal number of cycles is 40.

[0023] Figure 6 Comparative Examples 1, 2, 3, and 1 correspond to CC (a), NiMoO4 / CC (b), NiFe-PBA@NiMoO4 / CC (c), and NiOOH@NiFe-PBA / CC (d) in a solution containing 2 μmol·L⁻¹ -1 DA and 30 μmol L -1 0.1 mol·L⁻¹ of UA -1 DPV plot in PB (pH = 6.5).

[0024] Figure 7 The NiOOH@NiFe-PBA / CC corresponding to Example 1 was tested at 0.1 mol·L⁻¹. -1 DPV response of a solution of PB (pH = 6.5) to a mixed solution containing different concentration gradients of DA and UA.

[0025] Figure 8 The linear relationship between the electrochemical response of NiOOH@NiFe-PBA / CC in DA (left) and UA (right) and its concentration is shown in Example 1. Detailed Implementation

[0026] To further understand the present invention, the following description, in conjunction with the accompanying drawings and embodiments, will further illustrate the present invention, but does not limit the present invention in any way.

[0027] Example 1:

[0028] (a) Preparation of NiMoO4 / CC

[0029] Cut CC into 2 cm × 3 cm pieces, and ultrasonically wash them sequentially with anhydrous ethanol and deionized water for 15 min each. Then place them in a solution containing 30 mL of 15 mmol·L⁻¹. -1 The mixture was heated at 120°C for 3 hours in a dilute nitric acid reactor. After cooling and washing, the mixture was transferred to a 50 mL reactor, and 2.0 mmol Ni(NO3)2·6H2O and 0.5 mmol (NH4)6Mo7O were added. 24· 4H2O and 25 mL of deionized water were mixed evenly and reacted at 150 °C for 6 h. After cooling, washing and drying, the NiMoO4 / CC electrode was obtained.

[0030] (b) Preparation of NiFe-PBA@NiMoO4 / CC

[0031] The NiMoO4 / CC prepared in step (a) was placed in a 20 ml solution containing 0.6 mmol K3[Fe(CN)6] and reacted in an oil bath at 90 °C for 120 min. After washing and drying, the NiFe-PBA@NiMoO4 / CC electrode was obtained.

[0032] (c) Preparation of NiOOH@NiFe-PBA / CC

[0033] Using the NiFe-PBA@NiMoO4 / CC prepared in step (b) as the working electrode, a graphite rod as the counter electrode, and mercury / mercury oxide as the reference electrode, 1 mol·L -1 KOH was used as the electrolyte. In this three-electrode system, cyclic voltammetry was employed within a potential window of 0 to 1 V, at a rate of 100 mV·s. -1 Electrochemical reconstruction was performed after 40 rate scans to obtain the NiOOH@NiFe-PBA / CC electrode;

[0034] Example 2:

[0035] (a) Preparation of NiMoO4 / CC

[0036] Prepared according to the method and conditions of step (a) in Example 1;

[0037] (b) Preparation of NiFe-PBA@NiMoO4 / CC

[0038] Following the method and conditions of step (b) in Example 1, NiMoO4 / CC was placed in a 20 ml solution containing 0.4 mmol K3[Fe(CN)6] and kept in an oil bath at 90°C for 120 min to obtain the NiFe-PBA@NiMoO4 / CC electrode.

[0039] (c) Preparation of NiOOH@NiFe-PBA / CC

[0040] Prepared according to the method and conditions of step (c) in Example 1;

[0041] Example 3:

[0042] (a) Preparation of NiMoO4 / CC

[0043] Prepared according to the method and conditions of step (a) in Example 1;

[0044] (b) Preparation of NiFe-PBA@NiMoO4 / CC

[0045] Following the method and conditions of step (b) in Example 1, NiMoO4 / CC was placed in a 20 mL solution containing 1.0 mmol K3[Fe(CN)6] and kept in an oil bath at 90°C for 120 min to obtain the NiFe-PBA@NiMoO4 / CC electrode.

[0046] (c) Preparation of NiOOH@NiFe-PBA / CC

[0047] Prepared according to the method and conditions of step (c) in Example 1;

[0048] Example 4:

[0049] (a) Preparation of NiMoO4 / CC

[0050] Prepared according to the method and conditions of step (a) in Example 1;

[0051] (b) Preparation of NiFe-PBA@NiMoO4 / CC

[0052] Referring to the method and conditions of step (b) in Example 1, NiMoO4 / CC was placed in a 20 ml solution containing 0.6 mmol K3[Fe(CN)6] and kept in an oil bath at 90°C for 60 min to obtain the NiFe-PBA@NiMoO4 / CC electrode;

[0053] (c) Preparation of NiOOH@NiFe-PBA / CC

[0054] Prepared according to the method and conditions of step (c) in Example 1;

[0055] Example 5:

[0056] (a) Preparation of NiMoO4 / CC

[0057] Prepared according to the method and conditions of step (a) in Example 1;

[0058] (b) Preparation of NiFe-PBA@NiMoO4 / CC

[0059] Following the method and conditions of step (b) in Example 1, NiMoO4 / CC was placed in a 20 ml solution containing 0.6 mmol K3[Fe(CN)6] and kept in an oil bath at 90°C for 240 min to obtain the NiFe-PBA@NiMoO4 / CC electrode.

[0060] (c) Preparation of NiOOH@NiFe-PBA / CC

[0061] Prepared according to the method and conditions of step (c) in Example 1;

[0062] Example 6:

[0063] (a) Preparation of NiMoO4 / CC

[0064] Prepared according to the method and conditions of step (a) in Example 1;

[0065] (b) Preparation of NiFe-PBA@NiMoO4 / CC

[0066] Prepared according to the method and conditions of step (b) in Example 1;

[0067] (c) Preparation of NiOOH@NiFe-PBA / CC

[0068] Referring to the method and conditions of step (c) in Example 1, in a three-electrode system, at 100 mV·s -1 Electrochemical reconstruction was performed after 20 rate scans to obtain the NiOOH@NiFe-PBA / CC electrode;

[0069] Example 7:

[0070] (a) Preparation of NiMoO4 / CC

[0071] Prepared according to the method and conditions of step (a) in Example 1;

[0072] (b) Preparation of NiFe-PBA@NiMoO4 / CC

[0073] Prepared according to the method and conditions of step (b) in Example 1;

[0074] (c) Preparation of NiOOH@NiFe-PBA / CC

[0075] Referring to the method and conditions of step (c) in Example 1, in a three-electrode system, at 100 mV·s -1 Electrochemical reconstruction was performed after 60 rate scans to obtain the NiOOH@NiFe-PBA / CC electrode;

[0076] Comparative Example 1:

[0077] Cut CC into 2 cm × 3 cm pieces, and ultrasonically wash them sequentially with anhydrous ethanol and deionized water for 15 min each. Then place them in a solution containing 30 mL of 15 mmol·L⁻¹. -1In a reaction vessel containing dilute nitric acid, the mixture was heated at 120°C for 3 hours. After cooling and washing, pretreated carbon cloth, denoted as CC, was obtained.

[0078] Comparative Example 2:

[0079] (a) Preparation of NiMoO4 / CC

[0080] Prepared according to the method and conditions of step (a) in Example 1;

[0081] Comparative Example 3:

[0082] (a) Preparation of NiMoO4 / CC

[0083] Prepared according to the method and conditions of step (a) in Example 1;

[0084] (b) Preparation of NiFe-PBA@NiMoO4 / CC

[0085] Prepared according to the method and conditions of step (b) in Example 1;

[0086] Figure 1 SEM images of NiMoO4 / CC (a, d), NiFe-PBA@NiMoO4 / CC (b, e), and NiOOH@NiFe-PBA / CC (c, f) corresponding to Comparative Examples 2, 3, and 1, respectively. NiMoO4 / CC consists of smooth, interlaced nanorods with a cross-sectional diameter of approximately 200 nm. After ion exchange, NiFe-PBA nanocubes appear on the surface of the nanorods, which is due to the relative growth of MoO4... 2- Ni 2+ Easier to work with [Fe(CN)6] 3- Combined, Ni 2+ Diffusion outwards, internal MoO4 2- Partial dissolution leads to the formation of an internal hollow structure. The size of NiFe-PBA is approximately 200 nm, with the hollow structure having a diameter of approximately 150 nm. After electrochemical reconstruction, the size of the hollow nanorods did not change significantly, but the smooth surface became rough, and abundant edge planes were generated. This structure exposes more edge active sites.

[0087] Figure 2 The figures represent CC (a), NiMoO4 / CC (b), NiFe-PBA@NiMoO4 / CC (c), and NiOOH@NiFe-PBA / CC (d) corresponding to Comparative Examples 1, 2, 3, and 1, respectively, in a solution containing 0.1 mol L... −1 5.0 mmol L of KCl −1 [Fe(CN)6]3− / 4− 0.1 mol·L -1 The CV plot (left) and electrochemical impedance spectroscopy (right) of KCl solution. The left plot shows that Example 1 (curve d) has an interpeak potential of 269 mV and exhibits the highest redox current and the smallest redox peak potential difference (ΔE). p This indicates that the catalytic activity of the electrode material is improved, and the oxidation reaction rate of the redox probe is increased. This is because, compared to the comparative example, its hollow structure increases the number of edge active sites, the NiOOH formed on the surface improves the catalytic active sites, and the hydrophilicity facilitates the adsorption of the redox probe on the surface, thus exhibiting the best electrocatalytic activity. The semicircular diameter observed in the high-frequency region of the EIS spectrum in the right figure indicates the charge transfer resistance (R). ct ). The R of NiOOH@NiFe-PBA / CC corresponding to Example 1 ct The value is 0.90 Ω, significantly lower than the charge transfer resistance values ​​corresponding to Comparative Examples 1, 2, and 3, and this result is consistent with the CV results. This indicates that after electrochemical reconstruction, the target catalyst exhibits higher electron migration efficiency at the electrode-electrolyte interface. This is because the formation of high-valence nickel NiOOH exposes more edge active sites, improving electron and mass transport and enhancing electrochemical sensing performance.

[0088] Figure 3 The CV plots for different amounts of potassium ferricyanide in 20 mL solutions of Examples 1, 2, and 3 during the ion exchange step are shown: 0.6 mmol K3[Fe(CN)6] (a), 0.4 mmol K3[Fe(CN)6] (b), and 1.0 mmol K3[Fe(CN)6] (c). This indicates that the optimal amount of potassium ferricyanide is 0.6 mmol K3[Fe(CN)6].

[0089] Figure 4 The CV plots are for Examples 1, 4, and 5, showing the ion exchange time at 90°C for 120 min (a), 60 min (b), and 240 min (c). This indicates that the optimal ion exchange time is 120 min.

[0090] Figure 5 CV plots for electrochemical reconstruction at 20 (a), 40 (b), and 60 (c) cycles for Examples 1, 6, and 7. This indicates that the optimal number of cycles is 40.

[0091] Figure 6Comparative Examples 1, 2, 3, and 1 correspond to CC (a), NiMoO4 / CC (b), NiFe-PBA@NiMoO4 / CC (c), and NiOOH@NiFe-PBA / CC (d) in a solution containing 2 μmol·L⁻¹ -1 DA and 30 μmol L -1 0.1 mol·L⁻¹ of UA -1 The DPV curves in PB (pH = 6.5) show that the hollow structure in the NiOOH@NiFe-PBA / CC electrode increases the edge active sites, the NiOOH formed on the surface improves the catalytic active sites, and the oxygen-containing groups increase hydrophilicity, which is beneficial for the adsorption and catalysis of DA and UA molecules on the electrode surface, thus improving its electrochemical sensing performance. It is noteworthy that the increase in response signal for DA is more significant than that for UA, because the alkalinity of DA plays a regulatory role in detection. Specifically, when DA molecules are added, their alkalinity moderately increases the pH of the solution, significantly improving the solubility of DA molecules in the solution and increasing the number of detectable DA molecules; it also optimizes the redox reaction kinetics of DA on the electrode surface. Furthermore, DA and UA show oxidation peaks at 168 mV and 288 mV, respectively, on the NiOOH@NiFe-PBA / CC electrode, with a potential difference of 120 mV. The oxidation peak current is significantly higher than that of other modified electrodes, further enhancing its sensitivity and selectivity, which is beneficial for the simultaneous electrochemical detection of DA and UA.

[0092] Figure 7 The NiOOH@NiFe-PBA / CC corresponding to Example 1 was tested at 0.1 mol·L⁻¹. -1 The DPV response of the NiOOH@NiFe-PBA / CC electrode to mixed solutions containing different concentrations of DA and UA in a PB (pH = 6.5) solution was investigated. Oxidation peaks for DA and UA were observed at 0.168 V and 0.28 V, respectively, with the peak current increasing proportionally to the concentrations of DA and UA. This demonstrates that the sensing platform can achieve simultaneous electrochemical detection of DA and UA.

[0093] Figure 8 The linear relationship between the electrochemical response of NiOOH@NiFe-PBA / CC in Example 1 and its concentration in DA (left) and UA (right) is shown. As the DA concentration increases, I... pa The absolute value gradually increases (left), and the concentration of DA is related to I. pa At 0.05 μmol·L -1 ~20 μmol·L -1 A certain linear relationship exists within the range. The corresponding linear equation is: Ipa (DA) = -0.1814C (μmol·L) -1 ) - 0.0798 (R2=0.9789) (0.05~2.5 μmol·L -1 ), I pa (DA) = - 0.0335C (μmol·L -1 ) - 0.3622 (R2=0.9743) (0.25~20 μmol·L -1 Limit of detection (LOD): 4.7 nmol·L -1 (S / N=3), Sensitivity: 471.3 μA·μM -1 ·cm -2 As UA concentration continues to increase, I pa The absolute value gradually increases (right). The corresponding linear equation: I pa (UA) = - 0.0726C (μmol·L -1 ) - 0.6583 (R 2=0.8977) (5~25 μmol·L -1 ), I pa (UA) = - 0.1352C (μM) + 0.5765 (R2=0.9874) (25~55 μmol·L -1 LOD: 28.53 nmol·L -1 (S / N=3), Sensitivity: 117.76 μA·μM -1 ·cm -2 .

[0094] Table 1: Comparison of the sensing performance of the NiOOH@NiFe-PBA / CC electrode obtained in this invention with recently reported sensing performance in simultaneous detection of DA and UA.

[0095]

[0096] As can be seen from Table 1, the linear range of simultaneous detection of DA and UA using the NiOOH@NiFe-PBA / CC electrode described in this invention is close to or better than that of some modified electrodes reported in the literature, but the detection limit is significantly lower than the reported value. This indicates that the NiOOH@NiFe-PBA / CC self-supporting electrode has sensitive electrocatalytic performance and good selectivity for DA and UA, thus exhibiting excellent stability, sensitivity and selectivity.

[0097] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent conversion methods and shall be included within the protection scope of the present invention.

Claims

1. A NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode, characterized in that... The self-supporting electrode consists of carbon cloth and a NiOOH@NiFe-PBA heterostructure grown in situ on its surface. The NiOOH@NiFe-PBA heterostructure is obtained by first etching the in-situ grown nickel molybdate nanorods on the carbon cloth with K3[Fe(CN)6], and then electrochemically activating it under alkaline conditions using cyclic voltammetry. The carbon cloth is denoted as CC; the in-situ grown nickel molybdate nanorods on the carbon cloth are denoted as NiMoO4 / CC; the electrode after K3[Fe(CN)6] etching is denoted as NiFe-PBA@NiMoO4 / CC; and the NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode is denoted as NiOOH@NiFe-PBA / CC. The method for preparing the carbon cloth self-supporting electrode is characterized by comprising the following steps: (a) Preparation of NiMoO4 / CC CC was cut into 2 cm × 3 cm pieces, and ultrasonically washed successively with anhydrous ethanol and deionized water for 15 min each. Then it was placed in 30 mL of a solution containing 15 mmol·L⁻¹ water. -1 The mixture was heated at 120°C for 3 hours in a dilute nitric acid reactor. After cooling and washing, the mixture was transferred to a 50 mL reactor, and 2 mmol Ni(NO3)2·6H2O and 0.5 mmol (NH4)6Mo7O were added sequentially. 24 · 4H2O and 25mL of deionized water were mixed evenly and reacted at 150 °C for 6 h. After cooling, washing and drying, the NiMoO4 / CC electrode was obtained. (b) Preparation of NiFe-PBA@NiMoO4 / CC The NiMoO4 / CC prepared in step (a) was placed in a 20 mL solution containing 0.4~1.0 mmol K3[Fe(CN)6] and reacted in an oil bath at 90℃ for 30~240 min. After washing and drying, the NiFe-PBA@NiMoO4 / CC electrode was obtained. (c) Preparation of NiOOH@NiFe-PBA / CC Using the NiFe-PBA@NiMoO4 / CC prepared in step (b) as the working electrode, a graphite rod as the counter electrode, and mercury / mercury oxide as the reference electrode, 1 mol·L -1 KOH was used as the electrolyte. In this three-electrode system, the NiOOH@NiFe-PBA / CC electrode was obtained by electrochemical reconstruction using cyclic voltammetry. In step (c) of the preparation method, the cyclic voltammetry scan rate is 100 mV·s. -1 The scanning potential window was 0 to 1 V, and the number of scans was 20 to 60. The obtained NiOOH@NiFe-PBA / CC catalyst nanorods exhibited a hollow structure and significantly increased surface roughness. The surface oxygen-containing groups increased significantly, and the contact angle decreased significantly, showing enhanced surface hydrophilicity.

2. The NiOOH@NiFe-PBA modified carbon cloth self-supporting electrode according to claim 1, used for the simultaneous detection of dopamine and uric acid, is characterized in that... Using 0.1 mol / L pH 6.5 phosphate buffer as the supporting electrolyte, electrolyte solutions containing different concentrations of dopamine and uric acid, either alone or in mixtures, were added to the electrolytic cell. A NiOOH@NiFe-PBA / CC electrode was used as the working electrode, and differential pulse voltammetry was employed to detect the oxidation peak currents of dopamine and uric acid and their concentrations, respectively, and linear regression equations were obtained. The oxidation peak currents of dopamine and uric acid in the test sample were measured using the same method, and the contents of dopamine and uric acid in the test sample were obtained by substituting them into the linear regression equation.

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