Electrochemical sensor for detecting ortho-aminophenol as well as preparation method and application of electrochemical sensor

Abstract

The invention discloses an electrochemical sensor for detecting ortho-aminophenol as well as a preparation method and application of the electrochemical sensor, and relates to the technical field of electrochemical sensors. The CuWO4 (at) MoS2 composite material is obtained by compounding synergism of a high-specific-surface-area supporting structure, electron synergism of heterojunction accelerated charge separation and catalytic synergism of double active sites, and the CuWO4 (at) MoS2 composite material is used for modifying a glassy carbon electrode, so that the electrochemical sensor is constructed. The sensor shows good sensitivity, reproducibility and reliable stability to ortho-aminophenol, and can be used for detecting the content of ortho-aminophenol in a water body sample.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical sensors, and in particular to an electrochemical sensor for detecting o-aminophenol, a preparation method thereof, and applications thereof. Background Art

[0002] o-Aminophenol (OAP) is an allergenic substance with acute toxicity. Inhalation or skin contact can cause respiratory irritation, bronchial diseases, contact dermatitis, and eye damage. Excessive inhalation of OAP can lead to illnesses such as methemoglobinemia. Long-term exposure can cause allergic reactions and organ damage, necessitating strict occupational exposure limits. OAP is highly toxic in water and to aquatic organisms (such as fish and algae), disrupting the balance of aquatic ecosystems and significantly impacting the environment. Because this phenolic substance contains a benzene ring functional group, it readily oxidizes to form o-benzoquinone compounds, which are difficult to degrade. Therefore, a rapid and efficient method for detecting OAP is urgently needed, which is of great significance for environmental protection and human health. At present, the commonly used methods for detecting o-aminophenol include high performance liquid chromatography (HPLC), ultraviolet-visible spectrophotometry, gas chromatography-mass spectrometry (GC-MS), electrochemical sensing (EC) technology, etc. Among them, electrochemical analysis is widely used due to its advantages of simple operation, low detection cost, rapidity and high accuracy.

[0003] Molybdenum disulfide (MoS2), a transition metal sulfide, is composed of three atomic layers of S-Mo-S stacked by weak van der Waals forces. Within a single layer, Mo atoms are strongly covalently bonded to S atoms, forming a two-dimensional layered structure similar to graphene. This unique structure and excellent electrical properties have attracted considerable research interest in batteries and optoelectronic devices. However, the unmodified MoS2 surface lacks effective catalytic active sites, resulting in low electrochemical sensitivity. Van der Waals gaps hinder interlayer electron hopping, resulting in poor electrical conductivity, limiting its application. Copper tungstate (CuWO4), an n-type semiconductor material with excellent mechanical stability, is widely used in optical, magnetic, antibacterial, preservative, and dye applications, particularly due to its excellent electrical conductivity, which is attributed to its copper content. However, CuWO4 has a limited surface area. If MoS2 and CuWO4 can be combined and made to work together, their respective advantages can be maximized. However, there is currently no report on an electrochemical sensor based on CuWO4@MoS2 composite material that can be used to detect o-aminophenol in water samples. Summary of the Invention

[0004] To address the above shortcomings, the present invention provides an electrochemical sensor for detecting o-aminophenol, its preparation method, and application. This method obtains a CuWO4@MoS2 composite material through the synergy of a high specific surface area support structure, the electronic synergy of a heterojunction to accelerate charge separation, and the catalytic synergy of dual active sites, significantly improving the electrochemical performance of the material. The CuWO4@MoS2 composite material is then used to modify a glassy carbon electrode (GCE) to construct an electrochemical sensor. The sensor exhibits good sensitivity to o-aminophenol and can be used to detect the content of o-aminophenol in water samples. The specific technical solution is as follows:

[0005] A method for preparing an electrochemical sensor for detecting o-aminophenol comprises the following steps:

[0006] (1) Preparation of flower-like MoS2;

[0007] (2) Preparation of CuWO4@MoS2 composite material: MoS2 was first dispersed in deionized water, and then Cu(NO3)2·3H2O and Na2WO4·2H2O were added, and then the pH was adjusted to 8-8.5, and the mixture was stirred for 1-2 hours to obtain a suspension. The suspension was transferred to a reactor, reacted at 140-160°C for 20-24 hours, and cooled to room temperature. The cooled material was washed and vacuum dried to obtain the CuWO4@MoS2.

[0008] (3) Preparation of electrochemical sensor CuWO4@MoS2 / GCE: CuWO4@MoS2 was added to DMF and ultrasonically dispersed to obtain a CuWO4@MoS2 dispersion with a concentration of 1-1.5 mg / mL; the GCE surface was polished with Al2O3 polishing powder until it was smooth and mirror-like, washed with water, and dried with N2; the dispersion was dropwise applied to the surface of the dried GCE and allowed to dry naturally to obtain the CuWO4@MoS2 / GCE.

[0009] Furthermore, in step (1), the preparation method of the flower-like MoS2 is: adding Na2MoO4·2H2O and thiourea to deionized water respectively, continuously stirring until the mixture is uniformly dispersed, transferring the dispersed mixture to a reactor, reacting at 180-230°C for 20-24h, cooling to room temperature to obtain a black suspension, washing the black suspension, vacuum drying, and leaving it overnight to obtain flower-like MoS2.

[0010] Furthermore, the volume mass ratio of the deionized water to Na2MoO4·2H2O is 50 mL:(1-2) g; the volume mass ratio of the deionized water to thiourea is 50 mL:(3-4) g.

[0011] Furthermore, in step (2), the volume mass ratio of the deionized water and MoS2 is 40mL:(65-75)mg; the volume mass ratio of the deionized water and Cu(NO3)2·3H2O is 40mL:(17-17.5)mg; and the volume mass ratio of the deionized water and Na2WO4·2H2O is 40mL:(23-24)mg.

[0012] Furthermore, in step (2), the pH is adjusted using a NaOH solution with a concentration of 0.5-1.5 mol / L.

[0013] Furthermore, in step (2), the vacuum drying temperature is 65-75° C. and the time is 10-12 h.

[0014] Furthermore, in step (3), the dispersion is applied on the GCE surface in an amount of 3-5 μL.

[0015] The present invention also provides an electrochemical sensor CuWO4@MoS2 / GCE prepared by the preparation method.

[0016] Furthermore, the application is for the detection of o-aminophenol.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention obtains a CuWO4@MoS2 composite material through the synergy of a high specific surface area support structure, the electronic synergy of accelerated charge separation by the heterojunction, and the catalytic synergy of dual active sites, which significantly improves the electrochemical performance of the material. The CuWO4@MoS2 composite material is used to modify a glassy carbon electrode (GCE) to construct an electrochemical sensor. The sensor shows good sensitivity, reproducibility and reliable stability to o-aminophenol, and can be used to detect the content of o-aminophenol in water samples.

[0019] 2. The MoS2 layered structure of the present invention can provide a supporting substrate, and the interlayer embedded CuWO4 shortens the electron transmission path and inhibits agglomeration, forming a heterojunction with excellent electrochemical performance, so that CuWO4@MoS2 effectively improves the electron migration ability and enhances the structural stability, thereby improving the electrochemical activity. The sensor of the present invention has a large detection range for the concentration of o-aminophenol and a low detection limit, which can more accurately detect o-aminophenol in practical applications. Among them, the detection of o-aminophenol concentration in the range of 0.3-14.8μmol / L and 14.8-74.1μmol / L shows two linear sections with the electrochemical response peak current, respectively: I p (μA)=7.27×10 -2 C (μmol / L)-1.76×10 -2 (R 2=0.9983) and I p (μA) = 2.40 × 10 -2 C(μmol / L)+0.7(R 2 =0.9904), with a detection limit of 14.3 nmol / L. Meanwhile, the spike recovery method was used to detect actual o-aminophenol samples, with recovery rates ranging from 98.00% to 100.72%, indicating good results and indicating that the sensor of the present invention is accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments.

[0021] Figure 1 Comparison of the surface morphologies of CuWO4, MoSe2 and CuWO4@MoS2;

[0022] Figure 2 XRD comparison diagram (A) and local magnified diagram (B) of CuWO4, MoSe2 and CuWO4@MoS2;

[0023] Figure 3 Electrochemical cyclic voltammetry response diagram (A) and electrochemical impedance spectroscopy (B) of electrodes modified with different materials to o-aminophenol;

[0024] Figure 4 DPV response curve of CuWO4@MoS2 / GCE to o-aminophenol solution in PBS buffer solution (A), relationship between pH and oxidation peak current (B), and relationship between pH and oxidation peak potential (C);

[0025] Figure 5 The cyclic voltammetry curves of CuWO4@MoS2 / GCE at different scan rates (A) and the relationship between scan rate (v) and oxidation peak current (I pa ) relationship diagram (B);

[0026] Figure 6 Square wave voltammetry curves (A) and linear relationship curves (B) of different concentrations of o-aminophenol on the CuWO4@MoS2 / GCE surface. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0028] Example 1

[0029] A method for preparing an electrochemical sensor for detecting o-aminophenol comprises the following steps:

[0030] (1) Preparation of flower-like MoS2: 1 g of Na2MoO4·2H2O and 3 g of thiourea were added to 50 mL of deionized water, respectively, and stirred continuously until the mixture was uniformly dispersed. The dispersed mixture was transferred to a polytetrafluoroethylene reactor and reacted at 180°C for 20 h. The mixture was cooled to room temperature to obtain a black suspension. The black suspension was washed three times with deionized water and anhydrous ethanol, respectively, and dried at 60°C under vacuum conditions and left overnight to obtain black molybdenum disulfide powder (flower-like MoS2).

[0031] (2) Preparation of CuWO4@MoS2 composite material: first disperse 65mgMoS2 into 40mL deionized water, then add 17mgCu(NO3)2·3H2O and 23mgNa2WO4·2H2O, then use 0.5mol / L NaOH solution to adjust the pH to 8, continue stirring for 1h to obtain a suspension, transfer the suspension to a polytetrafluoroethylene reactor, react at 140℃ for 20h, cool to room temperature, wash the cooled material with deionized water and anhydrous ethanol three times respectively, and dry at 65℃ for 10h under vacuum conditions to obtain the CuWO4@MoS2.

[0032] (3) Preparation of electrochemical sensor CuWO4@MoS2 / GCE: CuWO4@MoS2 was added to DMF and ultrasonically dispersed to obtain a CuWO4@MoS2 dispersion with a concentration of 1 mg / mL; the GCE (Φ=3 mm before modification) was polished with Al2O3 polishing powder until the surface was smooth and mirror-like, washed with water, and dried with N2; 3 μL of the dispersion was dropwise applied to the surface of the dried GCE and allowed to dry naturally to obtain the CuWO4@MoS2 / GCE.

[0033] Example 2

[0034] A method for preparing an electrochemical sensor for detecting o-aminophenol comprises the following steps:

[0035] (1) Preparation of flower-like MoS2: 2 g of Na2MoO4·2H2O and 4 g of thiourea were added to 50 mL of deionized water, respectively, and stirred continuously until the mixture was uniformly dispersed. The dispersed mixture was transferred to a polytetrafluoroethylene reactor and reacted at 230°C for 24 h. The mixture was cooled to room temperature to obtain a black suspension. The black suspension was washed three times with deionized water and anhydrous ethanol, respectively, and dried at 60°C under vacuum conditions and left overnight to obtain black molybdenum disulfide powder (flower-like MoS2).

[0036] (2) Preparation of CuWO4@MoS2 composite material: first disperse 75 mg of MoS2 into 40 mL of deionized water, then add 17.5 mg of Cu(NO3)2·3H2O and 24 mg of Na2WO4·2H2O, then use a 1.5 mol / L NaOH solution to adjust the pH to 8.5, continue stirring for 2 hours to obtain a suspension, transfer the suspension to a polytetrafluoroethylene reactor, react at 160°C for 24 hours, cool to room temperature, wash the cooled material with deionized water and anhydrous ethanol three times respectively, and dry at 75°C for 12 hours under vacuum conditions to obtain the CuWO4@MoS2.

[0037] (3) Preparation of electrochemical sensor CuWO4@MoS2 / GCE: CuWO4@MoS2 was added to DMF and ultrasonically dispersed to obtain a CuWO4@MoS2 dispersion with a concentration of 1.5 mg / mL; the GCE (Φ=3 mm before modification) was polished with Al2O3 polishing powder until the surface was smooth and mirror-like, washed with water, and dried with N2; 5 μL of the dispersion was dropwise applied to the surface of the dried GCE and allowed to dry naturally to obtain the CuWO4@MoS2 / GCE.

[0038] Example 3

[0039] A method for preparing an electrochemical sensor for detecting o-aminophenol comprises the following steps:

[0040] (1) Preparation of flower-like MoS2: 1.8 g of Na2MoO4·2H2O and 3.5 g of thiourea were added to 50 mL of deionized water, respectively, and stirred continuously until the mixture was uniformly dispersed. The dispersed mixture was transferred to a polytetrafluoroethylene reactor and reacted at 200°C for 24 h. The mixture was cooled to room temperature to obtain a black suspension. The black suspension was washed three times with deionized water and anhydrous ethanol, respectively, and dried at 60°C under vacuum conditions and left overnight to obtain black molybdenum disulfide powder (flower-like MoS2).

[0041] (2) Preparation of CuWO4@MoS2 composite material: first disperse 70 mg MoS2 in 40 mL deionized water, then add 17.2 mg Cu(NO3)2·3H2O and 23.7 mg Na2WO4·2H2O, then use a 1 mol / L NaOH solution to adjust the pH to 8.5, continue stirring for 1 hour to obtain a suspension, transfer the suspension to a polytetrafluoroethylene reactor, react at 150°C for 24 hours, cool to room temperature, wash the cooled material with deionized water and anhydrous ethanol three times respectively, and dry at 70°C for 12 hours under vacuum conditions to obtain the CuWO4@MoS2.

[0042] (3) Preparation of electrochemical sensor CuWO4@MoS2 / GCE: CuWO4@MoS2 was added to DMF and ultrasonically dispersed to obtain a CuWO4@MoS2 dispersion with a concentration of 1 mg / mL; the GCE (Φ=3 mm before modification) was polished with Al2O3 polishing powder until the surface was smooth and mirror-like, washed with water, and dried with N2; 3-5 μL of the dispersion was dropwise applied to the surface of the dried GCE and allowed to dry naturally to obtain the CuWO4@MoS2 / GCE.

[0043] SEM, TEM and XRD characterization of composite materials

[0044] The morphology and structural characteristics of CuWO4, MoSe2, and CuWO4@MoS2 prepared in Example 3 were observed using a scanning electron microscope (SEM). (CuWO4 was prepared by adding 17.2 mg of Cu(NO3)2·3H2O and 23.7 mg of Na2WO4·2H2O to deionized water, adjusting the pH of the mixture to 8.5 with a 1 mol / L NaOH solution, and stirring for 1 h to obtain a suspension, which was then transferred to a polytetrafluoroethylene reactor and maintained at 150°C for 24 h.) Figure 1 As shown, MoSe2 appears as a uniform layered floret containing a large number of petal-like nanosheets ( Figure 1 A. Figure 1 B), this huge nanosheet can provide a higher specific surface area and more available active sites for further efficient electrochemical catalysis. CuWO4 presents irregular granular aggregates ( Figure 1 C), the dense packing between particles easily leads to a low specific surface area, which limits the exposure of active sites. The SEM image of CuWO4@MoS2 shows that CuWO4 is evenly dispersed on the surface of the layered florets of MoSe2 ( Figure 1 D). Under CuWO4@MoSe2 hybridization, the detached nanoparticles appear on the MoSe2 florets due to the sufficient loading of CuWO4.

[0045] CuWO4 and CuWO4@MoS2 were evaluated in detail by transmission electron microscopy (TEM). Figure 1 E further reveals the nanoscale structural details of CuWO4. Figure 1 CuWO4 nanoparticles are dispersed on the surface of the flower-shaped MoS2.

[0046] The crystallinity and phase purity of CuWO4, MoSe2 and CuWO4@MoS2 were analyzed by X-ray diffractometer (XRD). Figure 2 ,like Figure 2As shown in A, CuWO4 (blue curve) shows typical triclinic diffraction peaks at 2θ = 22.4° (-111), 29.3° (020), 36.2° (022), etc. The peaks are wide and the intensity is low, indicating that its grain size is small; hexagonal layered MoS2 (black curve), the peaks are at 14.1°, 33.2°, 39.4°, 48.9°, 58.8°, 69.1° for (002), (100), (103), (105), (110), (200), respectively, which match the standard results. In contrast, the diffraction peaks of CuWO4@MoS2 (red curve) are enhanced and sharp, such as (-111) and (020), and the crystallinity is significantly improved, but compared with the monomer CuWO4, it shifts to different degrees of angular directions ( Figure 2 B) indicates that the introduction of MoS2 induces compressive strain in the CuWO4 lattice. The stress effect at the heterojunction interface between the hexagonal layered structure of MoS2 and the CuWO4 lattice is systematically shifted, demonstrating that the two phases coexist through a heterojunction rather than simply physically mixing. This result demonstrates the successful preparation of the composite material and reveals the crucial role of heterojunction interface effects in enhancing crystal structure and performance.

[0047] Electrochemical performance analysis

[0048] Electrochemical test method: Add 100 μL of rutin standard solution of different concentrations to 10 mL of PBS buffer solution (pH 5.0, 0.1 mol / L). After incubation for 20 seconds, scan the SWV range from 0 to 0.6 V to draw a standard curve. When measuring actual samples, add an appropriate amount of sample solution to the PBS buffer solution and measure using this method. Electrochemical impedance spectroscopy was performed in 5 mmol / L [Fe(CN)6] 3- / 4- The test was carried out in a solution (containing 0.1 mol / L KCl) with a working potential of 0.2 V.

[0049] In a PBS buffer solution of pH 7.0 (containing 47.6 μmol / L o-aminophenol), the electrochemical responses of four different working electrodes, namely bare electrode (Bare / GCE), CuWO4 / GCE, MoS2 / GCE, and CuWO4@MoS2 / GCE (the preparation methods of CuWO4 / GCE and MoS2 / GCE are the same as that of CuWO4@MoS2 / GCE, all prepared by the method of Example 3) to o-aminophenol were studied by cyclic voltammetry (CV) at a potential range of -1 to 1 V and a scan rate of 0.1 V / s. Figure 3The results showed that a clear oxidation peak appeared at a potential of 0.21 V. CuWO4@MoS2 / GCE exhibited the highest peak current (3.7 μA), which was 3.7 times and 2.5 times that of MoS2 / GCE (1.0 μA) and CuWO4 / GCE (1.5 μA), respectively. This indicates that CuWO4@MoS2 / GCE has good electrocatalytic performance for o-aminophenol.

[0050] In 10mL 1mmol / L[Fe(CN)6] 3- / 4- Solution (containing 0.1 mol / L KCl) with a working potential of 0.2 V was used to investigate the differences in electron transfer rates on the surfaces of different modified electrodes using electrochemical impedance spectroscopy (EIS). Figure 3 As shown in B, the resistance of each material modified electrode (R ct ) is in the order of CuWO4 / GCE>CuWO4@MoS2 / GCE>MoS2 / GCE>Bare / GCE, indicating that there are significant differences in the conductivity and interfacial charge transfer efficiency of the materials. ct The largest value is mainly attributed to its poor conductivity and the obstruction of electron transmission path caused by particle aggregation; while the R ct It is higher than that of Bare / GCE, which may be related to the interlayer stacking defects of MoS2 and the carrier scattering caused by surface sulfur vacancies. It is worth noting that the R ct This is significantly lower than other modified electrodes, demonstrating a synergistic effect of the composite material: MoS2 acts as a conductive substrate to disperse CuWO4 nanoparticles, shortening the electron transfer path. Meanwhile, the hybridization of CuWO4 and MoS2 reduces the interfacial barrier and accelerates the electron transfer rate. The results demonstrate that optimizing the interface between materials can effectively improve charge transfer efficiency, and CuWO4 and MoS2 successfully hybridize.

[0051] Optimal pH analysis of the sensor of the present invention

[0052] Differential pulse voltammetry (DPV) was used in 10.0 mL PBS buffer solution (containing 47.6 μmol / L o-aminophenol) to investigate the effect of pH (pH 2.0-9.0) on peak current and peak potential. The measured parameters were: potential range -0.1 V to 0.7 V. Figure 4 As shown in (A and B), the oxidation peak current (I pa) initially increases and then decreases with increasing pH, reaching a maximum at pH 5.0 and then dropping sharply when the pH is greater than 6.0. This indicates that the electrochemical oxidation of o-aminophenol exhibits optimal activity at pH 5.0. This is likely due to the partial ionization of the phenolic hydroxyl and amino groups of o-aminophenol at pH 5.0, forming a molecular form that is both adsorbable and oxidatively active. Furthermore, the peak potential at pH 5.0 is 0.24 V, which effectively avoids oxidative interference from common coexisting substances (such as ascorbic acid and uric acid) in the low-potential region and improves detection selectivity. Therefore, the optimal pH value for this experiment was 5.0. Figure 4 The oxidation peak potential (E pa ) shifts negatively with increasing pH, and the potential-pH shows a good linear relationship (red line): E pa (V) = -5.51 × 10 -2 pH + 0.54 (R 2 =0.9876), with a slope of -0.055 V / pH, which is close to the theoretical value of -0.059 V / pH of the Nernst equation

[20] , indicating that the oxidation reaction of o-aminophenol is accompanied by the transfer of equal amounts of electrons (n) and protons (m).

[0053] Scan rate analysis

[0054] The cyclic voltammetric behavior of CuWO4@MoS2 / GCE prepared in Example 3 was studied in 10 mL of 0.1 mol / L PBS solution (pH 5.0, containing 47.6 μmol / L o-aminophenol) at a scan rate range of 0.02 to 0.09 V / s and a potential range of -0.6 to 0.8 V. Figure 5 As shown in A. As the scanning rate (v) increases, E pa Gradually move forward, I pa Gradually increases. v and I pa There is a good linear relationship ( Figure 5 B):I pa (μA)=15.7v(V / s)+4.18×10 -2 (R 2 =0.9933), indicating that the oxidation of o-aminophenol is mainly driven by adsorption. The electron transfer number (n) is an important parameter in electrochemical reaction kinetics. For adsorption-controlled processes, the value of n can be calculated according to the formula based on Laviron theory.

[0055]

[0056] F is the Faraday constant; Q represents the charge and Figure 5The values ​​in . R and T are the ideal gas constant and thermodynamic temperature, respectively. The average value of n is about 2. This shows that this electrochemical redox process involves 2 electrons and 2 protons, from which the reaction equation of o-aminophenol on the electrode is inferred. Unlike aniline or other substituted anilines, o-aminophenol has two groups (-NH2 and OH) that can be oxidized, and their relative positions are an important factor affecting the electrochemical oxidation of aminophenol. o-aminophenol is oxidized to quinoneimine through a two-electron / proton process, and then undergoes a slow chemical hydrolysis reaction, with the final product being o-benzoquinone. The electrochemical reaction mechanism of o-aminophenol is as follows:

[0057]

[0058] Standard curve

[0059] In PBS at pH 5.0, the SWV method was used to detect the response signals of o-aminophenol at different concentrations on the CuWO4@MoS2 / GCE prepared in Example 3. The results showed that as the concentration of o-aminophenol increased, the oxidation peak current value gradually increased, indicating that the detection of o-aminophenol using CuWO4@MoS2 / GCE is feasible. Figure 6 As shown in A, the peak current of electrochemical response showed two linear segments at 0.3-14.8 μmol / L and 14.8-74.1 μmol / L ( Figure 6 B), respectively: I p (μA)=7.27×10 -2 C (μmol / L)-1.76×10 -2 (R 2 =0.9983) and I p (μA) = 2.40 × 10 -2 C(μmol / L)+0.7(R 2 =0.9904), the detection limit was 2.70×10 -2 μmol / L.

[0060] Reproducibility, stability and anti-interference

[0061] Under the same conditions, the peak current response of the sensor prepared in Example 3 was studied for 7 days. During this period, the modified electrode was stored in a refrigerator at 4°C. The calculated relative standard deviation (RSD) of the current value was 2.07%. The results show that the working electrode has a long effective life and can be used for long-term monitoring. The response of five working electrodes to o-aminophenol under the same conditions was studied. The RSD of the calculated current value was 2.10%, indicating that the electrochemical sensor has significant reproducibility. In addition, to study the selectivity of the electrochemical sensor, the fluctuation of the current value in the presence of different common interfering compounds (equivalent to 100 times the concentration of o-aminophenol) at the same concentration of o-aminophenol was measured. The relative error (Er) was less than ±5%. As shown in Table 1, there was no significant interference, indicating that the electrochemical sensor has good anti-interference properties.

[0062] Table 1. Effects of interfering substances on the electrochemical response of CuWO4@MoS2 / GCE

[0063]

[0064]

[0065] Testing actual samples

[0066] To verify the potential of the CuWO4@MoS2 / GCE prepared in Example 3 for detecting o-aminophenol, o-aminophenol in river water was analyzed by SWV at the optimal pH. The feasibility of this method was verified using a spike-in recovery method. The results, shown in Table 2, showed recoveries ranging from 98.00% to 100.72%, with RSDs ranging from 1.20% to 2.89%. This sensor demonstrated satisfactory results and has potential for application in real-world samples.

[0067] Table 2 Analysis of actual sample spike recovery (N=5)

[0068]

[0069] In summary, the present invention utilizes CuWO4@MoS2 composite material to modify GCE and construct an electrochemical sensor for the detection of o-aminophenol. Compared with a single electrode, CuWO4@MoS2 / GCE has a larger electroactive area, which can effectively improve the electron transfer rate of the material and exhibit good electrocatalytic ability for o-aminophenol. o-Aminophenol follows a two-electron and two-proton electrochemical reaction process on CuWO4@MoS2 / GCE. The linear range of o-aminophenol detection by this method is 0.3-74.10 μmol / L, and the detection limit is 14.3 nmol / L. This method has a wide linear detection range, a low detection limit, high sensitivity, good reproducibility and stability, and good anti-interference ability, and can be applied to the detection of o-aminophenol content in river water.

[0070] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing an electrochemical sensor for detecting o-aminophenol, characterized in that: The following steps are involved: (1) Preparation of flower-like MoS2; (2) Preparation of CuWO4@MoS2 composite material: MoS2 was first dispersed in deionized water, and then Cu(NO3)2·3H2O and Na2WO4·2H2O were added, and then the pH was adjusted to 8-8.5, and the mixture was stirred for 1-2 hours to obtain a suspension. The suspension was transferred to a reactor, reacted at 140-160°C for 20-24 hours, and cooled to room temperature. The cooled material was washed and vacuum dried to obtain the CuWO4@MoS2. (3) Preparation of electrochemical sensor CuWO4@MoS2 / GCE: CuWO4@MoS2 was added to DMF and ultrasonically dispersed to obtain a CuWO4@MoS2 dispersion with a concentration of 1-1.5 mg / mL; the GCE surface was polished with Al2O3 polishing powder until it was smooth and mirror-like, washed with water, and dried with N2; the dispersion was dropwise applied to the surface of the dried GCE and allowed to dry naturally to obtain the CuWO4@MoS2 / GCE.

2. The method for preparing an electrochemical sensor for detecting o-aminophenol according to claim 1, wherein: In step (1), the preparation method of the flower-shaped MoS2 is: adding Na2MoO4·2H2O and thiourea to deionized water respectively, continuously stirring until the mixture is uniformly dispersed, transferring the dispersed mixture to a reactor, reacting at 180-230°C for 20-24h, cooling to room temperature to obtain a black suspension, washing the black suspension, vacuum drying, and leaving it overnight to obtain flower-shaped MoS2.

3. The method for preparing an electrochemical sensor for detecting o-aminophenol according to claim 2, wherein: The volume mass ratio of the deionized water to Na2MoO4·2H2O is 50 mL:(1-2) g; the volume mass ratio of the deionized water to thiourea is 50 mL:(3-4) g.

4. The method for preparing an electrochemical sensor for detecting o-aminophenol according to claim 1, wherein: In step (2), the volume mass ratio of the deionized water to MoS2 is 40 mL: (65-75) mg; the volume mass ratio of the deionized water to Cu(NO3)2·3H2O is 40 mL: (17-17.5) mg; and the volume mass ratio of the deionized water to Na2WO4·2H2O is 40 mL: (23-24) mg.

5. The method for preparing an electrochemical sensor for detecting o-aminophenol according to claim 1, wherein: In step (2), the pH is adjusted using a 0.5-1.5 mol / L NaOH solution.

6. The method for preparing an electrochemical sensor for detecting o-aminophenol according to claim 1, wherein: In step (2), the vacuum drying temperature is 65-75° C. and the time is 10-12 h.

7. The method for preparing an electrochemical sensor for detecting o-aminophenol according to claim 1, wherein: In step (3), the dispersion is applied to the GCE surface in an amount of 3-5 μL.

8. The electrochemical sensor CuWO4@MoS2 / GCE prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the electrochemical sensor prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The application is for the detection of o-aminophenol.

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