Coated alpha-AgI nano-particle, alpha-AgI nano-particle-GCE electrode and preparation method and application of alpha-AgI nano-particle-GCE electrode

Abstract

The invention relates to the technical field of inorganic functional materials, in particular to coated alpha-AgI nano-particles, an alpha-AgI nano-particle-GCE electrode and a preparation method and application of the coated alpha-AgI nano-particles and the alpha-AgI nano-particle-GCE electrode. The preparation method of the coated alpha-AgI nanoparticles comprises the following steps: (1) KI is dropwise added into a mixed solution of AgNO3 and polyvinylpyrrolidone, the polyvinylpyrrolidone in the mixed solution accounts for 8-13 wt% of the total mixed solution, and yellow precipitates are generated; and (2) filtering, washing and drying the yellow precipitate, and calcining the yellow precipitate at 220-240 DEG C to obtain the coated alpha-AgI nanoparticles. Alpha-AgI which is stable at room temperature is synthesized through a polymer coating and size adjusting strategy, and the alpha-AgI is used for constructing an electrochemical sensor to be applied to the field of urine iodine detection, so that a method reference is provided for iodine health level evaluation of iodine-deficient people.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic functional materials, in particular to a coated α-AgI nanoparticle, an α-AgI nanoparticle-GCE electrode and a preparation method and application thereof. BACKGROUND

[0002] Iodine is an essential nutrient for the synthesis of thyroid hormones in the human body, which can regulate growth and development and metabolism. The intake of iodine and human health presents an inverted "U" curve relationship. Both insufficient or excessive intake of iodine can lead to health problems. Iodine deficiency can lead to irreversible cretinism, pregnancy complications, goiter, impaired thyroid hormone secretion, mental disorders and cognitive impairment, etc. Excessive iodine can lead to hyperthyroidism, hypothyroidism, goiter and autoimmune thyroiditis, etc. More than 90% of iodine entering the human body is excreted out of the body in the form of urine through the kidneys, and more than 90% of iodine in urine exists in the form of iodide. Therefore, the urinary iodine level is the most sensitive indicator for judging the iodine nutritional status of the human body, and is also an important indicator for monitoring the iodine nutritional level of key population at present. The optimal concentration of urinary iodine concentration in normal human body is 100-199 μg / L, less than 20 μg / L is severe iodine deficiency, 20-49 μg / L is moderate iodine deficiency, 50-99 μg / L is mild iodine deficiency, and more than 300 μg / L is excessive iodine. The optimal concentration of urinary iodine in pregnant women is 150-249 μg / L, less than 150 μg / L is iodine deficiency, and more than 500 μg / L is excessive iodine. Therefore, only the development of a method for accurately detecting 10-1000 μg / L of urinary iodine can realize the evaluation of the health level of human urinary iodine.

[0003] At present, the methods for accurately determining urinary iodine in practice mainly include arsenic cerium catalytic spectrophotometry (Sandell-Kolthoff reaction) and inductively coupled plasma mass spectrometry (ICP-MS). Arsenic cerium catalytic spectrophotometry is derived from the fact that iodide can catalyze the reduction of Ce 4+ and As 3+the catalytic effect of the reaction between them, which can detect 0-300 μg / L of urinary iodine, if the sample is higher than 300 μg / L, it needs to be diluted and retested, the dilution process may affect the accuracy of the results; and the method has more steps of urine sample processing and reaction, which requires special equipment and skilled detection personnel; in addition, toxic reagents must be used and disposed of correctly during the detection process, therefore, this method is not suitable for on-site detection of a large number of urine samples. The linear range of inductively coupled plasma mass spectrometry for detecting urinary iodine is 0-1000 μg / L, although it is considered the gold standard, in order to eliminate the matrix effect, complex pretreatment of urine samples (such as dilution, digestion, etc.) is required. Due to high cost and technical requirements, ICP-MS has a low popularity rate in some resource-limited laboratories and clinical applications. In addition, in recent years, researchers have also developed a variety of methods for detecting urinary iodine. For example, the journal "Analytical chemistry" (DOI: 10.1021 / acs.analchem.3c02531) reported a real-time urinary iodine detection platform based on iodine-induced solid-phase fluorescence filtering effect, with a linear range of 65-500 μg / L, but this method can only indicate the iodine nutritional status of the human body: "deficiency", "normal" or "excess", and cannot detect the specific iodine concentration; the journal "Analytica Chimica Acta" (DOI: 10.1016 / j.aca.2020.09.011) reported a fluorescent probe, mixing dimeric DNA silver nanoclusters with carbon dots at a fluorescence intensity of 5:1, which is used for I - 3 6 μg / L, but the interference of Cl - needs to be completely eliminated by redox pretreatment of the urine sample. The journal "Talanta" (DOI: 10.1016 / j.talanta.2019.02.061) reported an iodine ion sensor based on a screen-printed carbon electrode, with a linear analysis range of 19-6.4 x 10 4 μg / L and a detection limit of 368.1 μg / L, in addition, high concentrations of chloride ions have a large interference on the determination. The concentration of chloride ions in urine is about 10 5 μg / L, which is much higher than that of iodine ions, therefore, this method is not suitable for human urinary iodine detection in terms of detection limit and selectivity.

[0004] ​​Although the existing methods have made some progress in the detection of urinary iodine, there are still problems such as detection range and detection limit not suitable for urinary iodine detection, easy to be interfered by other ions, etc. Therefore, it is urgent to develop an accurate, rapid, detection range covering human urinary iodine concentration (10-1000 μg / L) and good selectivity urinary iodine detection method. Compared with the above methods, electrochemical method for detecting urinary iodine has been widely concerned due to its advantages such as simplicity, rapidness, low cost, no influence of sample color or turbidity, wide linear range, real-time detection, etc.

[0005] At present, electrochemical methods generally use voltammetric sensors and potential sensors to detect iodide. For example, a voltammetric sensor based on graphite carbon nitride-chitosan composite modification was reported in the journal Microchemical Journal (DOI: 10.1016 / j.microc.2024.110430), which can detect urinary iodine in the range of 12.45-3.32 x 10 4 μg / L, with a detection limit of 16.6 μg / L; in the journal Endocrine Reviews (DOI: 10.1210 / endrev / bnab029), water-soluble porphyrin was alternately deposited with polypyrrole on a 2-aminoethanethiol modified silver electrode to prepare an iodide potential sensor, which can realize the detection of iodide in the range of 2.03 x 10 2 -1.27 x 10 7 μg / L, with a detection limit of 127 μg / L.

[0006] At the same time, AgI is widely used as raw material to construct electrochemical sensors for detecting urinary iodine. For example, a full-solid-state potential sensor based on AgI / Ag2S was constructed in the journal Sensors and Actuators B: Chemical (DOI: 110.1016 / j.snb.2004.02.038), with a detection range of 1.26 x 10 2 -1.26 x 10 6 μg / L, with a high detection limit (2538 μg / L), which is not suitable for urinary iodine detection; in the journal Electrochimica Acta (DOI: 10.1016 / j.electacta.2012.02.002), a β-AgI-based iodide electrochemical sensor was reported, which can respond to a wide range of iodide concentrations (1.66 to 1.66 x 10 8These studies prove the feasibility of AgI in the field of iodide detection, but the AgI selected in the above studies is mostly β phase, and most of the sensors constructed by β-AgI have high detection limit, which cannot detect low concentration of iodine, and further cannot predict the health status of iodine deficiency population.

[0007] AgI has α, β and γ phases, and β and γ phases are relatively stable at room temperature. α-AgI has conductivity comparable to liquid electrolyte (higher than ordinary β and γ phase AgI), which is an ideal material for constructing electrochemical sensors. However, it only exists stably above 147°C, and below 147°C it will irreversibly transform into β / γ phase with poor conductivity. The traditional method of stabilizing α phase in glass matrix by melting and quenching is not only complex (requiring high temperature rapid cooling), but also has poor stability, and the glass matrix is not suitable for constructing electrochemical sensors. Due to the above difficulties, there is no research on using α-AgI to construct iodide sensor.

[0008] Therefore, there is an urgent need for a method for preparing α-AgI stable at room temperature to break through the detection limit bottleneck of β-AgI sensor and realize high-sensitivity detection of low-concentration iodide. SUMMARY

[0009] The technical problem to be solved by the present application is to develop an accurate and sensitive electrochemical sensor to realize the detection of 10-1000 μg / L urinary iodine concentration, so as to provide a scientific basis for the evaluation of different iodine health levels of human body iodine deficiency, normal level and iodine excess. To this end, the present application provides a coated α-AgI nanoparticle, an α-AgI nanoparticle-GCE electrode and a preparation method and application thereof.

[0010] In order to achieve the above purpose, the present application provides a preparation method of coated α-AgI nanoparticles, comprising the following steps:

[0011] (1) adding 0.03-0.05M KI to a mixed solution of 0.03-0.05M AgNO3 and polyvinylpyrrolidone, wherein the polyvinylpyrrolidone accounts for 8-13wt% of the total mixed solution, to generate a yellow precipitate;

[0012] (2) filtering, washing and drying the yellow precipitate, and calcining at 220-240°C to obtain coated α-AgI nanoparticles.

[0013] In the reaction process of the present application, the Ksp of AgI generated by the reaction of KI and AgNO3 is 8.3×10 -17 , which is extremely small, and the concentration product of KI and AgNO3 in step (1) is much larger than the Ksp, so Ag + and I -The reaction for generating AgI is a transient precipitation reaction; and the coordination of PVP with Ag + belongs to a slower complexation reaction. Therefore, when KI is contacted with the mixed solution, it first reacts with AgNO3 to generate AgI, and then has a coating effect with PVP to form coated α-AgI nanoparticles.

[0014] In order to synthesize α-AgI stable at room temperature, the present application adopts a polymer coating and size adjustment strategy, uses polyvinylpyrrolidone (PVP) to coat AgI nanoparticles to form a polymer-nanoparticle interface effect. PVP as an Ag + conductor induces Ag + migration out of the interface, resulting in I - enrichment and lattice defects;

[0015] At the same time, by reducing the size of AgI nanoparticles, the specific surface area is increased, the surface energy is increased, and the energy barrier of α→β / γ phase transition is increased, so that the phase transition temperature is reduced.

[0016] Preferably, the speed of dropping in step (1) is 1-3 seconds / drop, and the dropping environment is under low temperature conditions of 10-15℃.

[0017] The present application mainly adopts the following three aspects of parameter control to ensure the reduction of the size of AgI nanoparticles:

[0018] 1. The speed of adding KI is controlled, and KI is slowly added into the AgNO3 / PVP mixed solution, which can avoid the generation of large particles caused by local supersaturation;

[0019] 2. The temperature is kept at 10-15℃ during the reaction of KI and the AgNO3 / PVP mixed solution, so as to reduce the ion migration rate and inhibit the growth;

[0020] 3. The PVP coating provides steric hindrance to inhibit the agglomeration of nanoparticles to form large particles.

[0021] Preferably, the calcination under the condition of 220-240℃ in step (2) includes the following specific temperature changes: starting from an initial temperature of 20-30℃, the temperature is raised at a speed of 3-8℃ / min, and after the temperature is raised to 220-240℃, high-temperature calcination is carried out under static air for 2-4h, and then natural cooling is carried out to room temperature.

[0022] Controlling the α phase is a technical difficulty in the preparation of α-AgI, and the present application controls the calcination temperature in detail when heating the phase transition, so as to ensure that the obtained α-AgI can maintain the α phase at room temperature.

[0023] Under the same technical concept, the present application also provides a coated α-AgI nanoparticle, which is prepared by the above preparation method, and the coated α-AgI nanoparticle maintains the α phase at room temperature.

[0024] The conventional AgI phase transition temperature is 147℃, and AgI is usually in the beta / gamma phase at room temperature. Figure 8 According to the XRD and CV curve of the AgI powder prepared at 160℃, the AgI powder is in the beta phase, and the conductivity is not as good as that of the alpha phase, so the electrochemical performance is not as good as that of the alpha phase. Figure 9 The scheme of the present application can maintain the alpha phase of the AgI powder synthesized at 220℃ at room temperature.

[0025] The coated alpha-AgI is irregularly round particles, and the average particle size is 10-30 nm; the structure of the coated alpha-AgI is a core-shell structure, the core structure is alpha-AgI particles, and the shell structure is a PVP coating layer.

[0026] Under the same technical concept, the present application also provides a coated alpha-AgI nanoparticle-GCE electrode, which comprises a glassy carbon electrode substrate and a coated alpha-AgI nanoparticle coating mixture prepared by the above method coated on the electrode substrate, and the coated alpha-AgI nanoparticle coating mixture comprises coated alpha-AgI nanoparticles and a perfluorosulfonic acid-based polymer.

[0027] The perfluorosulfonic acid-based polymer fixes the active material (alpha-AgI) on the electrode surface to construct an electrochemical sensor.

[0028] Preferably, the coating amount of the coated alpha-AgI nanoparticle coating mixture on the electrode substrate is 10-30 μL.

[0029] Preferably, the mass ratio / molar ratio of the coated alpha-AgI nanoparticles and the perfluorosulfonic acid-based polymer in the coated alpha-AgI nanoparticle coating mixture is 2.8:1-4.8:1.

[0030] Under the same technical concept, the present application also provides a preparation method of a coated alpha-AgI nanoparticle-GCE electrode, which comprises the following steps:

[0031] The coated alpha-AgI nanoparticles are mixed with 900-950 μL of water and 50-100 μL of a perfluorosulfonic acid-based polymer, the mass of the coated alpha-AgI nanoparticles is 10-30 mg, the concentration of the perfluorosulfonic acid-based polymer is 3-8%, and ultrasonic dispersion is performed to obtain a mixed slurry; 10-30 μL of the mixed slurry is coated on a glassy carbon electrode substrate to prepare a coated alpha-AgI nanoparticle-GCE electrode.

[0032] Under the same technical concept, the application further provides an application of the coated alpha-AgI nanoparticle-GCE electrode, and the coated alpha-AgI nanoparticle-GCE electrode is used for constructing an electrochemical sensor to detect the concentration of urinary iodine.

[0033] Preferably, the detection scheme selects a cyclic voltammetry method.

[0034] The above scheme of the application has the following beneficial effects:

[0035] (1) The application synthesizes stable alpha-AgI at room temperature through a polymer coating and size adjustment strategy, and applies the alpha-AgI to the field of urinary iodine detection by constructing an electrochemical sensor; the high ionic conductivity of the alpha-AgI improves the electrochemical performance of the sensor, so as to realize the detection of low-concentration iodine and provide a method reference for the evaluation of the iodine health level of iodine-deficient people.

[0036] (2) The application provides a preparation technology of stable alpha-AgI at room temperature; although the alpha-AgI has higher conductivity than beta and gamma-AgI, it only exists at a temperature higher than 147℃, and will be converted into beta and gamma phases at a temperature lower than the temperature; the application synthesizes stable alpha-AgI at room temperature through a polymer coating and size adjustment strategy; the PVP is used to coat the AgI nanoparticles to form a polymer-nanoparticle interface effect; meanwhile, the size of the AgI nanoparticles is reduced to improve the specific surface area, so as to increase the surface energy and increase the energy barrier of the alpha→beta / gamma phase transition, so as to finally realize the reduction of the phase transition temperature, and thus synthesize stable alpha-AgI at room temperature.

[0037] (3) The coated alpha-AgI nanoparticle-GCE electrode and the sensor constructed by using the alpha-AgI as raw material can realize the detection of 10-1500 μg / L urinary iodine concentration, the detection limit is 2.84 μg / L, the detection sensitivity is 5.07 μA μg L -1 cm -2 , the detection limit is lower than that of most existing methods, and can cover the urinary iodine concentration (100-500 μg / L) recommended by the World Health Organization, so as to provide a scientific basis for the evaluation of different iodine health levels of human body iodine deficiency, normal level and iodine excess.

[0038] (4) The coated alpha-AgI nanoparticle-GCE electrode sensor constructed by the application can resist the interference of common interfering substances (urea, creatinine, glycine, Na + , Ca 2+ , Cl - , etc.) in urine, and has a low relative standard deviation value, which indicates that the electrode has good precision and reproducibility. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art will be briefly introduced. Obviously, the following drawings are some embodiments of the present application, and other related drawings can be obtained by a person of ordinary skill in the art without any creative effort.

[0040] Figure 1 Preparation flow chart of the coated α-AgI nanoparticle-GCE electrode of the present application;

[0041] Figure 2 Field emission scanning electron microscope (SEM) image of the PVP-coated α-AgI prepared in Example 1 of the present application;

[0042] Figure 3 High resolution transmission electron microscope (HRTEM) image of the PVP-coated α-AgI prepared in Example 1 of the present application;

[0043] Figure 4 SEM image of the PVP-coated β-AgI prepared in Comparative Example 1 of the present application;

[0044] Figure 5 SEM image of the PVP-coated β / γ-AgI prepared in Comparative Example 2 of the present application;

[0045] Figure 6 SEM image of the PVP-coated β-AgI prepared in Comparative Example 3 of the present application;

[0046] Figure 7 SEM image of the AgI without PVP coating prepared in Comparative Example 4 of the present application;

[0047] Figure 8 X-ray diffraction (XRD) pattern of Example 1 and Comparative Examples 1-3 of the present application;

[0048] Figure 9 Cyclic voltammograms of the electrodes prepared from the PVP-coated AgI powders prepared under different phase transition temperature conditions in Example 1 and Comparative Examples 1-3 of the present application for detecting 100 μg / L KI solution;

[0049] Figure 10 Cyclic voltammograms of the coated α-AgI nanoparticle-GCE electrode prepared in Example 1 of the present application for detecting KI (a) and calibration curve of the function of KI concentration and current response (b);

[0050] Figure 11 Test results of the anti-interference performance of the coated α-AgI nanoparticle-GCE electrode in Example 1 of the present application;

[0051] Figure 12 The precision test results of the coated α-AgI nanoparticle-GCE electrode in the embodiment 1 of the present application are as follows:

[0052] Figure 13 The repeatability test results of the coated α-AgI nanoparticle-GCE electrode in the embodiment 1 of the present application are as follows. DETAILED DESCRIPTION

[0053] In order to make the technical problems solved by the present application, the technical solutions and advantages clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0054] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0055] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, it can be a locking connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or a communication inside two elements. For a person of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0056] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0057] Embodiment 1

[0058] The present embodiment provides a preparation method of coated α-AgI nanoparticles, comprising the following steps:

[0059] (1) 0.05M KI was added dropwise into a mixed solution of 0.05M AgNO3 and polyvinylpyrrolidone (PVP) at a rate of 1-3 seconds / drop, the dropwise adding environment was at a low temperature of 10-15°C, the PVP content was 10 wt% of the mixed solution of AgNO3 and polyvinylpyrrolidone (PVP), and a yellow-green precipitate was generated;

[0060] (2) The yellow-green precipitate was filtered, washed, and dried, the obtained product was heated in a muffle furnace from an initial temperature of 20°C at a heating rate of 5°C / min, and after being heated to 220°C, the product was calcined at a high temperature under static air for 3h, and then naturally cooled to room temperature to obtain coated α-AgI nanoparticles.

[0061] The coated α-AgI nanoparticles were α-AgI@PVP powders, and X-ray diffraction testing was performed thereon, and the obtained spectrum is shown in FIG. 1. Figure 8 The XRD results show that the prepared AgI powder is a body-centered cubic structure, and is α-phase AgI at room temperature;

[0062] Figure 2 and Figure 3 are SEM and HRTEM images of the α-AgI of the present embodiment. Figure 2 The results of FIG. 1 show that due to the coating effect of PVP, the specific morphology of the AgI particles is a core-shell structure, the core structure is α-AgI particles, and the shell structure is a PVP coating layer, the particles are uniformly dispersed, the particle size is uniform, and the size is between 10-30 nm. Figure 3 The two crystal lattice spacings of the α-AgI in FIG. 1 are 0.358 nm and 0.253 nm, respectively, which correspond to the (110) and (200) crystal planes of α-AgI, which are consistent with the XRD results of Figure 8 confirm that the synthesized AgI is α-phase, and can exist stably at room temperature;

[0063] The present embodiment provides a preparation method of a coated α-AgI nanoparticle-GCE electrode, which comprises the following steps:

[0064] The above-synthesized 20 mg α-AgI was mixed with 950 μL water and 50 μL of a 5% concentration of a perfluorosulfonic acid resin (Nafion), and ultrasonic treatment was performed for half an hour to obtain uniformly dispersed slurry, the mass ratio of the coated α-AgI nanoparticles and the perfluorosulfonic acid resin (Nafion) was 3.8, and the slurry was coated on a glassy carbon electrode substrate and dried with a red lamp, the coating amount was 10-30 μL, and a coated α-AgI nanoparticle-GCE electrode was obtained.

[0065] The overall preparation process of the coated α-AgI nanoparticle to the coated α-AgI nanoparticle-GCE electrode is shown in FIG. 2. Figure 1 ​

[0066] A coated α-AgI nanoparticle-GCE electrode sensor was constructed using coated α-AgI nanoparticles. The prepared coated α-AgI nanoparticle-GCE electrode served as the working electrode, a Pt electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode. Cyclic voltammetry was used to detect the current response of the electrode to KI solution, with a voltage range of -1.0 to 1.0 V and a scan rate of 50 mV / s.

[0067] Figure 10 (a) Cyclic voltammetry curve of KI detection by the coated α-AgI nanoparticle-GCE electrode in Example 1 of this invention; (b) Calibration curve of KI concentration as a function of current response. Figure 10 Calculations showed that the detection limit for KI using the coated α-AgI nanoparticle-GCE electrode was 2.84 μg / L, the detection range was 10-1500 μg / L, and the sensitivity was 5.07 μA / μg / L. -1 cm -2 The electrochemical sensor developed in this invention can detect urinary iodine concentrations ranging from 10 to 1500 μg / L, providing a scientific basis for assessing different iodine health levels in humans, including iodine deficiency, normal levels, and iodine excess. Furthermore, the detection limit (2.84 μg / L) is lower than the World Health Organization's assessment standard for iodine deficiency (urinary iodine content less than 20 μg / L), thus this sensor holds promise for detecting urinary iodine levels in iodine-deficient individuals.

[0068] Figure 11 The above are the anti-interference performance test results of the coated α-AgI nanoparticle-GCE electrode in Example 1 of this invention; the coated α-AgI nanoparticle-GCE electrode sensor can resist common interfering substances in urine (urea, creatinine, glycine, Na+). + Ca 2+ Cl - Interference from (etc.);

[0069] Figure 12 The results show the precision test results of the coated α-AgI nanoparticle-GCE electrode in Example 1 of this invention. Figure 12 As shown, the relative standard deviation (RSD) was 1.62% when the same solution was tested 7 times using the same electrode.

[0070] Figure 13 The results show the reproducibility test results of the coated α-AgI nanoparticle-GCE electrode in Example 1 of this invention. The same solution was tested seven times using seven coated α-AgI nanoparticle-GCE electrodes, and the RSD was 2.07%, indicating that the electrode has good precision and reproducibility.

[0071] Comparative Example 1:

[0072] The comparative example provides a preparation method of coated β-AgI nanoparticles, which is completely consistent with Example 1 except that the only difference is that the heating phase change is carried out at a high temperature of 160°C in a muffle furnace for 3h.

[0073] The prepared sample is characterized by SEM, as shown in FIG. 2, the micro-morphology of the coated β-AgI nanoparticles is irregular circular particles, and the particle size is between 15-40nm; in addition, X-ray diffraction test is also carried out, and the obtained spectrum is as shown in FIG. 3, the AgI powder prepared at 160°C is β phase. Figure 4 Figure 8 The prepared coated β-AgI nanoparticles are used to prepare β-AgI nanoparticles-GCE electrodes and β-AgI / GCE sensors in the same scheme as Example 1, and the current response of the electrode to 200 μg / L KI solution is detected by cyclic voltammetry, the voltage is-0.8-1.2 V, and the scanning rate is 50 mV / s. According to the size of the current response of the electrode to the same concentration of KI, the detection performance is judged, and the performance test diagram is as shown in FIG. 4, the current response of the β-AgI / GCE sensor prepared at 160°C to 200 μg / L KI solution is 51.29 μA.

[0074] The prepared sample is characterized by SEM, as shown in FIG. 2, the micro-morphology of the coated β-AgI nanoparticles is irregular circular particles, and the particle size is between 15-40nm; in addition, X-ray diffraction test is also carried out, and the obtained spectrum is as shown in FIG. 3, the AgI powder prepared at 160°C is β phase. Figure 9 The prepared sample is characterized by SEM, as shown in FIG. 2, the micro-morphology of the coated β-AgI nanoparticles is irregular circular particles, and the particle size is between 15-40nm; in addition, X-ray diffraction test is also carried out, and the obtained spectrum is as shown in FIG. 3, the AgI powder prepared at 160°C is β phase.

[0075] Comparative Example 2:

[0076] The comparative example provides a preparation method of a mixture of coated β-AgI nanoparticles and coated γ-AgI nanoparticles, which is completely consistent with Example 1 except that the only difference is that the heating phase change is carried out at a high temperature of 180°C in a muffle furnace for 3h.

[0077] Figure 5 The prepared sample is characterized by SEM, as shown in FIG. 2, the micro-morphology of the coated β-AgI nanoparticles is irregular circular particles, and the particle size is between 15-40nm; in addition, X-ray diffraction test is also carried out, and the obtained spectrum is as shown in FIG. 3, the AgI powder prepared at 160°C is β phase. Figure 8 The prepared sample is characterized by SEM, as shown in FIG. 2, the micro-morphology of the coated β-AgI nanoparticles is irregular circular particles, and the particle size is between 15-40nm; in addition, X-ray diffraction test is also carried out, and the obtained spectrum is as shown in FIG. 3, the AgI powder prepared at 160°C is β phase.

[0078] The prepared sample is characterized by SEM, as shown in FIG. 2, the micro-morphology of the coated β-AgI nanoparticles is irregular circular particles, and the particle size is between 15-40nm; in addition, X-ray diffraction test is also carried out, and the obtained spectrum is as shown in FIG. 3, the AgI powder prepared at 160°C is β phase.​​Figure 9 As shown in FIG. 6, the current response of the β / γ-AgI / GCE sensor prepared at 180°C to 200 μg / L KI solution was 97.01 μA.

[0079] Comparative Example 3

[0080] This comparative example provides a preparation method of coated β-AgI nanoparticles, which is completely consistent with Example 1 except that the only difference is that the heating phase change is performed at a high temperature of 200°C in a muffle furnace for 3h.

[0081] The prepared sample was subjected to SEM characterization, and the results are shown in FIG. 8. Figure 6 As shown in FIG. 8, the micro-morphology of the coated β-AgI nanoparticles is irregular granular, and the particle size is uneven, between 10-50 nm. Electrochemical test and X-ray diffraction test were performed, and the obtained spectrum is shown in FIG. 9. Figure 8 As shown in FIG. 9, the AgI powder prepared at 200°C is in β phase.

[0082] The obtained coated β-AgI nanoparticles were used to prepare β-AgI nanoparticle-GCE electrodes and β-AgI / GCE sensors in the same scheme as Example 1. The current response of the electrodes to 200 μg / L KI solution was detected by cyclic voltammetry, the voltage was-0.8-1.2 V, and the scanning rate was 50 mV / s. The detection performance was judged according to the size of the current response of the electrodes to the same concentration of KI; and the performance test graph is shown in FIG. 10. Figure 9 As shown in FIG. 10, the current response of the β-AgI / GCE sensor prepared at 200°C to 200 μg / L KI solution was 134.76 μA.

[0083] Comparative Example 4

[0084] This comparative example provides a preparation method of AgI particles, which is completely consistent with Example 1 except that the only difference is that 0.05M KI was added to 0.05M AgNO3, and no PVP solution was added.

[0085] The prepared AgI powder was subjected to SEM characterization, and the results are shown in FIG. 12. Figure 7 As shown in FIG. 12, the AgI particles without PVP coating have poor dispersibility, most of which are aggregated together to form irregular agglomeration, and the particle size is above 1 μm, which is much larger than the above-synthesized PVP-coated nano-AgI.

[0086] Electrochemical performance comparison test results

[0087] Example 1 and Comparative Examples 1-3 were subjected to cyclic voltammetry test in 200 μg / L KI solution, and the detection performance was judged by comparing the size of the response current. The performance test graph is shown in FIG. 13. Figure 9The results are shown in Table 1. The electrode prepared at 220°C is α-phase AgI, and has higher electrochemical activity and higher response to KI of the same concentration due to its high ionic conductivity.

[0088] Table 1: Cyclic voltammetry response current of different electrodes to 200 μg / L KI Serial number AgI powder phase Response current (pA) Comparative Example 1 β phase 51.29 Comparative Example 2 β and γ phases 97.01 Comparative Example 3 β phase 134.76 Example 1 α phase 163.56

[0089] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of the present application.

Claims

1. A method for preparing coated α-AgI nanoparticles, characterized by, The method comprises the following steps: (1) adding 0.03-0.05M KI dropwise into a mixed solution of 0.03-0.05M AgNO3 and polyvinylpyrrolidone, wherein the polyvinylpyrrolidone accounts for 8-13wt% of the total mixed solution, to generate a yellow precipitate; (2) filtering, washing and drying the yellow precipitate, and calcining the yellow precipitate at 220-240℃ to obtain the coated α-AgI nanoparticles.

2. The production method according to claim 1, wherein The speed of the dropwise addition in step (1) is 1-3 seconds / drop, and the dropwise addition is performed under a low-temperature condition of 10-15℃.

3. The production method according to claim 1, wherein The calcining at 220-240℃ in step (2) comprises the following temperature variation: starting from an initial temperature of 20-30℃, increasing the temperature at a speed of 3-8℃ / min, and then calcining at a high temperature under static air for 2-4h after the temperature is increased to 220-240℃, and then naturally cooling to room temperature.

4. A coated α-AgI nanoparticle, characterized in that, The coated α-AgI nanoparticles are prepared by the preparation method in any one of claims 1-2, and the coated α-AgI nanoparticles maintain the α phase at room temperature.

5. The production method according to claim 4, wherein The coated α-AgI is irregularly circular particles with an average particle size of 10-30nm, and the structure of the coated α-AgI is a core-shell structure, wherein the core structure is an α-AgI particle, and the shell structure is a PVP coating layer.

6. A coated α-Agl nanoparticle-GCE electrode, characterized in that, The coated α-AgI nanoparticle-GCE electrode comprises a glassy carbon electrode substrate and a coated mixture of the coated α-AgI nanoparticles on the electrode substrate, wherein the coated mixture of the coated α-AgI nanoparticles comprises the coated α-AgI nanoparticles and a perfluorosulfonic acid-based polymer, and the coated mixture of the coated α-AgI nanoparticles is prepared by any one of the preparation methods in claims 1-3 or any one of the coated α-AgI nanoparticles in claims 4-5.

7. The coated a-Agl nanoparticle-GCE electrode of claim 6, wherein the coating layer is a layer of a compound represented by the following formula (1): ###0001### (1) wherein R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X represents a halogen atom. The coated mixture of the coated α-AgI nanoparticles on the electrode substrate has a coating amount of 10-30μL.

8. The coated a-Agl nanoparticle-GCE electrode of claim 6, wherein, The mass ratio of the coated α-AgI nanoparticles to the perfluorosulfonic acid-based polymer in the coated mixture of the coated α-AgI nanoparticles is 2.8:1-4.8:

1.

9. A method for preparing a coated α-AgI nanoparticle-GCE electrode, characterized by, The method comprises the following steps: The coated α-AgI nanoparticles are mixed with 900-950μL water and 50-100μL perfluorosulfonic acid-based polymer, the coated α-AgI nanoparticles have an added mass of 10-30mg, the perfluorosulfonic acid-based polymer has a concentration of 3-8%, and the mixture is ultrasonically dispersed to obtain a mixed slurry; and 10-30μL of the mixed slurry is coated on a glassy carbon electrode substrate to prepare a coated α-AgI nanoparticle-GCE electrode.

10. Use of a coated α-AgI nanoparticle-GCE electrode, characterized in that The coated α-AgI nanoparticle-GCE electrode is used to construct an electrochemical sensor for detecting the concentration of urinary iodine.

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