A kind of all-solid-state sodium ion selective electrode and preparation method and application

Abstract

The application discloses a kind of full solid sodium ion selective electrode, preparation method and application, wherein full solid sodium ion selective electrode includes electrode matrix, the surface of the electrode matrix is coated with ion-electron transduction layer, and the ion-transduction layer includes Sn-MoS2 heterojunction material.The application uses Sn-MoS2 heterojunction material to construct full solid sodium ion selective electrode, by loading Sn on the surface of MoS2, under the premise that the morphology of MoS2 itself is not changed, the material capacitance is increased by interface effect, and the hydrophobicity is increased by increasing the specific surface area, so as to construct Sn-MoS2 heterojunction material.The detection of sodium ion has good potential response and excellent potential stability.

Description

Technical Field

[0001] This invention relates to the field of ion-selective electrode technology, and in particular to an all-solid-state sodium ion-selective electrode based on Sn-MoS2 heterojunction material, its preparation method, and its application. Background Technology

[0002] With the rapid development of wearable technology, combining all-solid-state ion-selective electrodes with wearable technology to fabricate wearable sensing devices has become a research hotspot in electrochemical sensors. All-solid-state ion-selective electrodes, as a new generation of potentiometric ion sensors, show a wider range of applications due to their unique advantages. However, the stability and reproducibility of the interfacial potential remain key research challenges for all-solid-state ion-selective electrodes. Current research reports that introducing various solid contact functional materials, such as conductive polymers or nanomaterials, as the ion-electron transduction layer of all-solid-state ion-selective electrodes can significantly improve their long-term stability and reproducibility. However, the potential stability of conductive polymers is easily affected by factors such as light, oxygen, and water layers. Nanomaterials have also been chosen as the ion-electron transduction layer for all-solid-state ion-selective electrodes, but because the ion-to-electron transduction process is asymmetrical, the solid contact functional material needs a sufficiently large capacitance to minimize the polarization of the solid contact. Furthermore, a certain degree of hydrophobicity can suppress the formation of an interfacial water layer, thereby maintaining the stability of the interfacial potential. Therefore, developing solid contact functional materials with large capacitance and high hydrophobicity as ion-electron transduction layers is currently a key research focus for all-solid-state ion-selective electrodes.

[0003] Transition metal sulfides are often used as electrode materials in electrochemical applications due to their unique properties, such as high theoretical capacitance and large surface areas with various morphologies. MoS2, in particular, exhibits excellent charge storage due to its layered structure, thus increasing capacitance; furthermore, its wide pore size distribution increases its specific surface area. However, the low conductivity of MoS2 is one of the main reasons for its deteriorated performance in electrochemical applications.

[0004] The sandwich structure of MoS2 (S-Mo-S) exhibits strong covalent bonds between the Mo-S layers and van der Waals interactions between the SS layers. Therefore, its performance can be tuned through embedding, forming heterostructures, and reducing size. Introducing hierarchical heterostructures can increase reactive sites and improve electrochemical performance. SnS2 possesses excellent electrochemical properties such as tunable spacing, high conductivity, and high theoretical capacity. Conductivity can be improved by loading Sn onto the MoS2 surface to form Sn-MoS2 heterojunction materials. In Sn-MoS2 heterojunction materials, the electronic structure of the MoS2 surface is influenced by SnS2, altering the physical and chemical properties of the interface. This simultaneously increases capacitance and hydrophobicity, resulting in an all-solid-state sodium ion selective electrode with good potential response and excellent potential stability for sodium ion detection. Summary of the Invention

[0005] The purpose of this invention is to provide an all-solid-state sodium ion-selective electrode, its preparation method, and its application. This all-solid-state sodium ion-selective electrode solves the problem of interface potential stability in all-solid-state sodium ion-selective electrodes, and is effective for Na+ ion selection. + It has a good response and a stable potential.

[0006] The specific technical solution of the present invention is as follows:

[0007] The first objective of this invention is to provide an all-solid-state sodium ion selective electrode, comprising an electrode substrate, wherein the surface of the electrode substrate is coated with an ion-electron transduction layer, and the ion-transduction layer is made of Sn-MoS2 heterojunction material.

[0008] In a further embodiment, the Sn-MoS2 heterojunction material is loaded at a concentration of 0.6-1.8 mg / cm³ on the all-solid-state ion-selective electrode. 2 .

[0009] In a further embodiment, the preparation method of the Sn-MoS2 heterojunction material includes the following steps:

[0010] (1) Thiourea, molybdenum source and tin source are added to water and magnetically stirred to obtain a dispersion;

[0011] (2) The dispersion was subjected to a one-step hydrothermal reaction, and the reaction product was washed and dried to obtain Sn-MoS2 heterojunction material.

[0012] Preferably, the molybdenum source is at least one of ammonium molybdate, sodium molybdate, and potassium molybdate;

[0013] The tin source is at least one of stannous chloride and stannous chloride;

[0014] The molar ratio of thiourea, molybdenum source, and tin source is 6:0.25-0.5:1-1.5;

[0015] The temperature of the first-step hydrothermal reaction is 200-240℃, and the time is 10-15 hours.

[0016] A second objective of this invention is to provide a method for preparing the above-mentioned all-solid-state sodium ion selective electrode, which includes the following steps:

[0017] (1) The Sn-MoS2 heterojunction material was ultrasonically dispersed in water to prepare a dispersion;

[0018] (2) The dispersion is drop-coated onto the pretreated electrode substrate, left to stand and dry naturally to form an ion-transduction layer on the surface of the electrode substrate;

[0019] (3) The sodium ion selective membrane liquid is drop-coated onto the ion-transconducting layer, and then left to stand and dry naturally to obtain the all-solid sodium ion selective electrode.

[0020] In a further embodiment, the concentration of the dispersion in step (1) is 8-20 mg / mL;

[0021] The electrode substrate includes a glassy carbon electrode, a screen-printed electrode, or a gold electrode;

[0022] The pretreatment of the electrode substrate in step (2) includes alcohol wiping, polishing, ultrasonic cleaning and drying.

[0023] In a further embodiment, the sodium ion selective membrane solution in step (3) is obtained by mixing sodium ion carrier II, high molecular polymer, plasticizer and lipophilic macromolecule, dissolving in a solvent, and then stirring.

[0024] The sodium ion selective membrane has a loading of 10-20 mg / cm² on the all-solid sodium ion selective electrode. 2 .

[0025] Sodium ion carrier II is an existing one, and its chemical name is: N,N′-dibenzyl-N,N′-diphenyl-1,2-phenyldioxydiacetamide.

[0026] The method for preparing the sodium ion selective membrane is as follows: sodium ion carrier II, polymer, plasticizer and lipophilic macromolecule are dissolved in a solvent to obtain a sodium ion selective membrane solution, the sodium ion selective membrane solution is drop-coated onto the surface of the ion-electron transduction layer and dried to form a sodium ion selective membrane.

[0027] In the sodium ion selective membrane solution, the total concentration of sodium ion carrier, polymer, plasticizer and lipophilic macromolecule is 80-150 mg / ml.

[0028] In a further embodiment, the polymer includes any one or more of polyvinyl chloride, polyvinyl acetate, and polymethyl methacrylate;

[0029] The plasticizer includes any one or more of di-n-octyl sebacate, diisooctyl sebacate, 2-nitrophenyl octyl ether, and bis(2-ethylhexyl) sebacate.

[0030] The lipophilic macromolecules include any one or more of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, potassium tetrakis(4-chlorophenyl)borate, potassium tetrakis(pentafluorophenyl)borate, and sodium tetraphenylborate;

[0031] The solvent is tetrahydrofuran, cyclohexanone, methanol, or acetonitrile.

[0032] A third objective of this invention is to provide an application of the aforementioned all-solid-state sodium ion-selective electrode for detecting Na in solution. + .

[0033] A fourth objective of this invention is to provide a wearable sensor comprising the aforementioned all-solid-state sodium ion selective electrode.

[0034] This invention utilizes the interaction between SnS2 and MoS2 electrons at the junction interface in Sn-MoS2 heterostructures to simultaneously increase the capacitance and hydrophobicity of the material, providing an effective approach for maintaining a stable potential in all-solid-state sodium ion selective electrodes based on Sn-MoS2 heterostructures as solid contact layers.

[0035] Compared with the prior art, the present invention has the following superior effects:

[0036] This invention is the first to utilize Sn-MoS2 heterojunction material as the ion-electron transconductance layer of an all-solid-state sodium ion selective electrode. High-conductivity SnS2 material is loaded onto the flower-shaped surface of MoS2 to construct a heterojunction interface. Without changing the morphology of MoS2 itself, the material capacitance is increased through the interaction of the electronic structure of the heterojunction interface, and the hydrophobicity is increased through the interface effect. Thus, a Sn-MoS2 heterojunction material with good capacitance and hydrophobicity is constructed.

[0037] The Sn-MoS2 heterojunction material prepared by this invention not only has a larger capacitance than MoS2 and SnS2, but also has higher hydrophobicity, effectively stabilizing the interface potential.

[0038] This application uses Sn-MoS2 heterojunction material as the ion-transconducting layer to construct an all-solid-state sodium ion selective electrode, thereby greatly improving the long-term stability of the all-solid-state sodium ion selective electrode and the problem of interface potential drift. Attached Figure Description

[0039] Figure 1 In the image, a, b, and c are SEM images of MoS2, SnS2, and Sn-MoS2 heterojunction materials, respectively; d is a TEM image of the Sn-MoS2 heterojunction material; and e is an EDS energy spectrum of the Sn-MoS2 heterojunction.

[0040] Figure 2 XRD patterns, infrared spectra, and Raman spectra of Sn-MoS2 heterojunction materials, MoS2, and SnS2;

[0041] Figure 3 The results of cyclic voltammetry tests are for Sn-MoS2 heterojunction materials, MoS2, and SnS2.

[0042] Figure 4 In the diagram, ac represents the BET specific surface area test data for Sn-MoS2 heterojunction material, MoS2, and SnS2, respectively; d represents the contact angle test data.

[0043] Figure 5 The scanning measurement spectra and high-resolution scan images of each material;

[0044] Figure 6 The results are the loading of the ion-transduction layer.

[0045] Figure 7 The open-circuit potential response test diagrams of each electrode prepared in Example 3 are shown.

[0046] Figure 8 The constant current chronopotential test diagrams of each electrode prepared in Example 3 are shown.

[0047] Figure 9 The water layer test and phosgene interference test results for each electrode prepared in Example 3 are shown below.

[0048] Figure 10 The results show the reversibility test results of the Sn-MoS2 / Na+-ISE electrode prepared in Example 3. Detailed Implementation

[0049] Example 1

[0050] The preparation process of the Sn-MoS2 heterojunction material in this invention is as follows:

[0051] 6 mM thiourea, 0.25 mM ammonium molybdate tetrahydrate, and 1 mM stannous chloride were added to 30 mL of ultrapure water, and then the mixture was magnetically stirred for 15 minutes to obtain a black turbid solution. After the solution was evenly dispersed, it was transferred to a 50 mL high-pressure reactor and hydrothermally reacted at 220 °C for 12 hours. After the reaction was completed, the mixture was naturally cooled, the product was collected, and washed three times with ultrapure water and ethanol, respectively. The product was then transferred to a vacuum oven and dried for 12 hours to obtain the Sn-MoS2 heterojunction material.

[0052] The Sn-MoS2 heterojunction material prepared above was compared with existing MoS2 and SnS2 materials. Among them:

[0053] Comparative Example 1:

[0054] The preparation process of MoS2 is as follows: 6 mM thiourea and 0.25 mM ammonium molybdate tetrahydrate were added to 30 mL of ultrapure water, and then the mixture was magnetically stirred for 15 minutes to obtain a colorless and transparent solution. After the solution was evenly dispersed, it was transferred to a 50 mL high-pressure reactor and hydrothermally reacted at 220 °C for 12 hours. After the reaction was completed, the mixture was naturally cooled, the product was collected, and washed three times with ultrapure water and ethanol, respectively. Then the product was transferred to a vacuum oven and dried for 12 hours to obtain MoS2 material.

[0055] Comparative Example 2:

[0056] The preparation process of SnS2 is as follows: 6 mM thiourea and 1 mM stannous chloride were added to 30 mL of ultrapure water, and then the mixture was magnetically stirred for 15 minutes to obtain a white turbid solution. After the solution was evenly dispersed, it was transferred to a 50 mL high-pressure reactor and hydrothermally reacted at 220 °C for 12 hours. After the reaction was completed, the mixture was naturally cooled, the product was collected, and washed three times with ultrapure water and ethanol, respectively. Then the product was transferred to a vacuum oven and dried for 12 hours to obtain SnS2 material.

[0057] Example 2:

[0058] Cyclic voltammetry tests were performed on the Sn-MoS2 heterojunction, MoS2, and SnS2 materials prepared in Example 1, Comparative Example 1, and Comparative Example 2, respectively. The results are as follows: Figure 6 As shown.

[0059] Figure 6 In the figure, a, c, and e are the optimization curves of the loading of Sn-MoS2 heterojunction, MoS2, and SnS2 materials on the electrode surface by cyclic voltammetry; b, d, and f are the corresponding integral curves.

[0060] The results showed that the optimal concentration of Sn-MoS2 heterojunction dispersion for the electrode surface was 14 mg / mL, i.e., the loading was 0.14 mg; the optimal concentration of MoS2 dispersion for the electrode surface was 12 mg / mL, i.e., the loading was 0.12 mg; and the optimal concentration of SnS2 dispersion for the electrode surface was 16 mg / mL, i.e., the loading was 0.16 mg.

[0061] Figure 1 In the figures, a, b, and c represent the HRTEM images of MoS2, SnS2, and Sn-MoS2 heterojunction materials, respectively, and the insets are the corresponding SEM images. Compared to MoS2 and SnS2, Figure 1 The image shows that the lattice stripe spacing of the Sn-MoS2 heterojunction material has obvious boundaries. Specifically, a lattice spacing of 0.617 nm corresponds to the (002) crystal plane of MoS2, and a lattice spacing of 0.325 nm corresponds to the (100) crystal plane of SnS2. Furthermore, combined with... Figure 1 The TEM image of the Sn-MoS2 heterojunction material, represented by d, shows that SnS2 particles are loaded on the edge surface of MoS2, thus proving the successful construction of the Sn-MoS2 heterojunction.

[0062] Figure 1 In the figure, e is the EDS energy spectrum of the Sn-MoS2 heterojunction material, which shows that the Sn-MoS2 heterojunction material contains the three elements S, Mo and Sn.

[0063] Figure 2 In Figure 'a', XRD patterns of Sn-MoS2 heterojunction material, MoS2, and SnS2 are shown. The results indicate that Sn-MoS2 possesses characteristic peaks of both MoS2 and SnS2. Specifically, the characteristic peaks at 14.28°, 33.5°, and 57.96° are attributed to the (002), (101), and (110) crystal planes of 2H-MoS2 (JCPDS, No. 37-1492), respectively, while the characteristic peaks at 26.65°, 52.21°, and 66.38° are attributed to the (100), (111), and (202) crystal planes of 2T-SnS2 (JCPDS, No. 23-0667), respectively. The peak intensity of Sn-MoS2 is lower than that of MoS2. This may be attributed to the fact that SnS2 covers the surface of MoS2 and shows a slight shift in diffraction angle compared to the bulk 2H-MoS2. This is because hydrolyzed ammonia is embedded in the interlayer spacing of MoS2 during the hydrothermal reaction, resulting in a randomly stacked layered structure of MoS2 during growth.

[0064] Figure 2 In the image, b represents the infrared spectra of Sn-MoS2 heterojunction material, MoS2, and SnS2. The absorption peak of Sn-MoS2 heterojunction material appears in the 1610-1620 cm⁻¹ range.-1 and 3430-3440cm -1 This is due to the stretching vibration of the OH bonds in water molecules. 580-590cm -1 The absorption peak at 660-670 cm⁻¹ is due to the stretching vibration of the Mo-S bond in MoS₂. -1 The absorption peak is due to the vibration of the Sn-S bond in SnS2, indicating that the Sn-MoS2 heterojunction contains both Mo-S bonds and Sn-S bonds.

[0065] Figure 2 Image c shows the Raman spectra of the Sn-MoS2 heterojunction material, MoS2, and SnS2. The SnS2 sample exhibits a significant peak at approximately 316 cm⁻¹, which is attributed to the A1g mode, i.e., the out-of-plane stretching of S atoms in the SnS2 sample. The MoS2 sample shows a peak at approximately 381 cm⁻¹. -1 and 408cm -1 Two main peaks are observed, corresponding to the E12g and A1g vibrational modes, respectively, representing the in-plane vibrational mode of S atoms and the out-of-plane vibrational mode of Mo and S atoms in the MoS2 sample. Furthermore, the Sn-MoS2 heterojunction material exhibits both MoS2 and SnS2 vibrational modes simultaneously. This indicates the successful preparation of the Sn-MoS2 heterojunction material.

[0066] Cyclic voltammetry was performed using a three-electrode system. The three-electrode system was constructed using MoS2, SnS2, and Sn-MoS2 heterojunction materials as working electrodes, a platinum wire electrode as the counter electrode, and Ag / AgCl as the reference electrode.

[0067] Electrochemical impedance spectroscopy (EIS) was performed using the three-electrode system described above in a mixed solution of 5.0 mM K₃[Fe(CN)₆] and 0.1 M KCl. The initial potential was the open-circuit potential, the scan frequency range was 0.01 Hz–100 kHz, the scan rate was 100 mV / s, the potential range was -0.5 V to +0.5 V, and the excitation amplitude was 10 mV. The results are as follows: Figure 3 As shown in Figure a, the CV curve of the Sn-MoS2 heterojunction material is approximately rectangular, exhibiting pseudocapacitive behavior. Therefore, at the same scan rate, compared to MoS2 and SnS2, the Sn-MoS2 heterojunction material has a larger CV area, indicating that the Sn-MoS2 heterojunction material has a higher charge storage capacity, exhibiting maximum capacitance.

[0068] EIS chart as follows Figure 3Among them, compared with MoS2 and SnS2, the Sn-MoS2 heterojunction material has a low charge transfer impedance, revealing a rapid charge transfer process between the electrode and the electrolyte interface, indicating that the heterojunction interface of the Sn-MoS2 heterojunction material promotes charge transfer and can regulate the electronic structure, thereby improving the conductivity of the Sn-MoS2 heterojunction material.

[0069] In addition, theoretically, the peak current (i) in the CV curve follows a power-law relationship with the scan rate (v): i = av b (logi = loga + blogv), where both a and b are constants. If 0.5 < b < 1, the electrochemical process is diffusion-controlled, and if b > 1, the electrochemical process is surface-controlled. For MoS2 and SnS2, b > 0.5, indicating that the electrochemical process is diffusion-controlled, while for the Sn-MoS2 heterojunction material, b is approximately 1, indicating that the electrochemical process of the Sn-MoS2 heterojunction is surface-controlled. The specific relationship between the peak current and the scan rate is as Figure 3 shown in b of

[0070] The specific surface area of the sample was measured using a Builder 4200 instrument, the contact angle was measured using a DSAHT17C high-temperature contact angle measuring instrument, and the wettability of the surface water droplets of the above materials was tested using the sessile drop method.

[0071] The N2 adsorption-desorption experiment is as Figure 4 shown. The Sn-MoS2 heterojunction material has the largest specific surface area of 186.31 m 2 / g ( Figure 4 in a), which is much larger than that of MoS2 at 15.45 m 2 / g ( Figure 4 in b) and SnS2 at 5.71 m 2 / g ( Figure 4 in c). a-c are the corresponding pore size distribution diagrams. According to the IUPAC standard, the N2 adsorption-desorption isotherm shows a type-IV H3 hysteresis loop, indicating that the Sn-MoS2 heterojunction material has a mesoporous structure. The pore size distribution range in the figure is 1.0 - 80.0 nm, and the average pore size is 4.04 nm, further confirming that the Sn-MoS2 heterojunction material is a porous structure.

[0072] Combined with the analysis of the TEM image of the Sn-MoS2 heterojunction, the uniform growth of flaky SnS2 particles on the surface of flower-like MoS2 particles greatly increases the specific surface area of the MoS2 and SnS2 materials. The large specific surface area and wide pore size distribution of the Sn-MoS2 heterojunction material result in Figure 4In the middle (d), it exhibits the largest contact angle (132°), which, compared to MoS2 (contact angle of 79.9°) and SnS2 (contact angle of 105°), increases the hydrophobicity of the material.

[0073] Figure 5 The X-ray photoelectron spectra of each material are shown, where 'a' represents the scanning measurement spectra of Sn-MoS2 heterojunction, MoS2, and SnS2. Specifically, Mo and S can be detected in the MoS2 spectrum, Sn and S can be detected in the SnS2 spectrum, and Mo, Sn, and S can be detected simultaneously in the Sn-MoS2 heterojunction. High-resolution spectra of Mo 3d, Sn 3d, and S 2p were further investigated.

[0074] like Figure 5 As shown in Figure b, Mo is located at 228.4 eV in MoS2. 4+ Compared to the 3d5 / 2 peak, the peak corresponding to the Sn-MoS2 heterojunction material is located at 228.9 eV, indicating electron transfer at the Sn-MoS2 heterojunction interface. This contrasts with the peak at 231.7 eV in MoS2. 3+ Compared to the 3d³ / ² peak, the Sn-MoS₂ heterostructure peak exhibits two characteristic peaks at 232.1 and 233.3 eV, indicating the simultaneous presence of Mo in the Sn-MoS₂ heterostructure material. 3+ and Mo 4+ This indicates the presence of structural vacancies on the surface of the Sn-MoS2 heterojunction material. The peak of MoS2 at 225.7 eV belongs to the S2s peak of the Mo-S bond. After Sn loading, the S2s peak splits into two peaks at 225.4 eV and 226.5 eV, which are attributed to the chemical states of the Sn-S and Mo-S bonds in the Sn-MoS2 heterojunction material, respectively, indicating the successful preparation of the Sn-MoS2 heterojunction material. Furthermore, the peak at 236 eV in the Sn-MoS2 heterojunction originates from Mo... 6+ The 3d³ / 2 pattern indicates that partial oxidation occurred after Sn loading. The high-resolution spectrum of S²p is as follows: Figure 5 As shown in Figure d, the two peaks at 161.7 and 163 eV can be attributed to the S2p3 / 2 and S2p1 / 2 regions of S in MoS2, respectively. Compared to the Sn-MoS2 heterojunction (161.4 eV and 162.7 eV), the binding energy shifts to lower positions, indicating an increase in S vacancies. Next, the Sn 3d XPS spectra were compared, as shown... Figure 5 As shown in -c, SnS2 exhibits two typical peaks at 487.3 eV and at 495.7 eV, with a binding energy higher than the Sn 3d value of the Sn-MoS2 heterojunction.

[0075] In summary, it can be concluded that the electronic structure in the Sn-MoS2 heterojunction is optimized after Sn loading, the interaction of the electronic structure occurs at the interface of the Sn-MoS2 heterojunction, and spontaneous electrons can be transferred from SnS2 to MoS2 through the Sn-S-Mo heterojunction.

[0076] Example 3:

[0077] The preparation process of the all-solid-state sodium ion selective electrode is as follows:

[0078] 1) Preparation of sodium ion selective membrane solution (Na + -ISM):

[0079] A mixture of 2.5 mg sodium ion carrier II (1 wt%), 82.25 mg polyvinyl chloride (32.9 wt%), 164.3 mg di-n-octyl sebacate (65.7 wt%), and 1 mg sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (0.4 wt%) was dissolved in 2.5 mL of tetrahydrofuran and magnetically stirred for 6 h to obtain a sodium ion selective membrane solution with a concentration of 102 mg / mL, which was then sealed and stored for later use.

[0080] 2) Pretreatment of glassy carbon electrode: The glassy carbon electrode with a diameter of 3 mm was polished on deerskin with 0.3 μm alumina, and then ultrasonically cleaned in sequence with 50% dilute nitric acid, ethanol and deionized water for later use.

[0081] 3) Preparation of dispersion: The Sn-MoS2 heterojunction material, MoS2, and SnS2 powder prepared in Example 1 were ultrasonically dispersed in deionized water to form a uniform dispersion.

[0082] 4) Using a pipette, drop 10 μL of uniformly dispersed Sn-MoS2 heterojunction material, MoS2, and SnS2 dispersion onto the surfaces of different glassy carbon electrodes (3 mm in diameter) treated in step 2), and then dry them completely in a fume hood to form an ion-transduction layer on the surface of the glassy carbon electrode.

[0083] 5) Drop 100 μL of the sodium ion selective membrane solution prepared in step 1) onto the surface of the electrode modified in step 4), and place it in a fume hood for 12 h to air dry to obtain Sn-MoS2 / Na+-ISE electrode, MoS2 / Na+-ISE electrode and SnS2 / Na+-ISE electrode respectively.

[0084] The Sn-MoS2 / Na+-ISE electrode, MoS2 / Na+-ISE electrode, and SnS2 / Na+-ISE electrode prepared above were tested for their respective properties, as detailed below:

[0085] Open Circuit Potential Response (OCPT) Test:

[0086] Dynamic potential response testing is performed using the open-circuit potential testing method. For example... Figure 7 As shown, where Figure 7 Figures a and b show the potential response curve and the corresponding calibration plot, respectively. The figures show that the Nernst slope for Sn-MoS2 / Na+-ISE detection is 57.86 mV / dec, and the detection limit is 1.82 × 10⁻⁶ M, achieving ultra-low level detection of Na+ with near-Nernst response.

[0087] Constant current chronopotential (CP) test:

[0088] By applying a polarization current of ±1 nA, the Et curves of the all-solid-state sodium ion selective electrode were recorded after each electrode was held for 60 s under these extreme current conditions. The potential drift of the prepared electrode can be calculated based on the slope (ΔE / Δt) of the Et curve. The results are as follows: Figure 8 As shown in Figure a, the chronopotential curves of the Sn-MoS2 / Na+-ISE electrode, MoS2 / Na+-ISE electrode, and SnS2 / Na+-ISE electrode were measured in 0.1M NaCl solution. The potential drift of the Sn-MoS2 / Na+-ISE electrode was 1.43 μV / s, that of the MoS2 / Na+-ISE electrode was 7.05 μV / s, and that of the SnS2 / Na+-ISE electrode was 79.15 μV / s. Clearly, the Sn-MoS2 heterojunction, acting as an ion-electron transduction layer, can more effectively maintain the potential stability of the all-solid-state sodium ion-selective electrode. Furthermore, this experiment also calculated the corresponding capacitance (C) value using an approximate equation: ΔE / Δt=i / C. The results show that the capacitance of Sn-MoS2 is 699 μF, which is much larger than that of MoS2 (142 μF) and SnS2 (12 μF). Figure 8 Figure b shows the potential results of the Sn-MoS2 / Na+-ISE electrode, MoS2 / Na+-ISE electrode, and SnS2 / Na+-ISE electrode measured continuously over a long period in 0.1M NaCl solution. Specifically, Sn-MoS2 / Na+-ISE exhibits a potential drift of 1.37 μV / h, which is much smaller than that of MoS2 / Na+-ISE (8.89 μV / h) and SnS2 / Na+-ISE (18.25 μV / h). This indicates that Sn-MoS2 has the best long-term stability as an ion-electron transduction layer, and this stability is attributed to its large capacitance and hydrophobicity.

[0089] Water layer test:

[0090] By placing each electrode in an environment containing the main ion (Na) + ) and interfering ions (K +The presence or absence of a water layer was assessed by alternating open-circuit potential (OCPT) tests over several hours in a solution containing [a specific electrode]. The water layer test results for each electrode are shown below. Figure 9 As shown in Figure a, when the solution is changed from the host ion solution to a solution containing interfering ions, the potentials of the MoS2 / Na+-ISE and SnS2 / Na+-ISE electrodes show a reverse potential shift, indicating the presence of an aqueous layer at the interface between the ion-electron transduction layer and the ion-selective membrane. This reverse potential shift is attributed to K+ diffusion into the aqueous layer via the ISM, leading to a change in concentration on the back side of the ISM and a significant potential shift. In contrast, the Sn-MoS2 / Na+-ISE electrode, due to its surface-controlled electrochemical processes and hydrophobicity, does not show a significant potential shift, indicating that an aqueous layer has not formed.

[0091] In addition, the effects of N2, O2, and CO2 on GC / Sn-MoS2 / Na+-ISE were evaluated by recording the potential response of the electrodes in 0.1M NaCl solution. Before the potential test, the solution was bubbled with N2, O2, and CO2 sequentially for 0.5 hours to remove gases from the solution. Furthermore, the effect of light on the electrodes was studied by turning the light on and off. The light and gas interference tests for each electrode in 0.1M NaCl solution are as follows: Figure 9 As shown in Figure b, no significant potential fluctuations were observed when the electrode was exposed to N2, O2, CO2, and light, indicating that the all-solid-state sodium ion selective electrode based on the Sn-MoS2 heterojunction can resist these interferences well.

[0092] Reversibility test:

[0093] In 10 -3 -10 -1 Potential response tests were conducted under a continuous concentration gradient of M NaCl. The reversibility test results are as follows: Figure 10 As shown, the corresponding potential values ​​were maintained at different concentrations in two consecutive cycles, indicating that the prepared Sn-MoS2 / Na+-ISE electrode has good reversibility, providing a good foundation for further integration with wearable technology.

[0094] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to the embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. An all-solid-state sodium-ion selective electrode comprising an electrode substrate, characterized by: The surface of the electrode substrate is covered with an ion-electron transconductance layer, and the ion-electron transconductance layer is made of SnS2-MoS2 heterojunction material. The preparation method of the SnS2-MoS2 heterojunction material includes the following steps: (1) Thiourea, molybdenum source and tin source are added to water and magnetically stirred to obtain a dispersion; (2) The dispersion was subjected to a one-step hydrothermal reaction, and the reaction product was washed and dried to obtain SnS2-MoS2 heterojunction material.

2. The all-solid-state sodium-ion selective electrode according to claim 1, characterized in that: The SnS2-MoS2 heterojunction material was loaded at 0.6-1.8 mg / cm³ on the all-solid-state sodium ion selective electrode. 2 .

3. The all-solid-state sodium ion selective electrode according to claim 1, characterized in that: The molybdenum source is at least one of ammonium molybdate, sodium molybdate, and potassium molybdate. The tin source is at least one of stannous chloride and stannous chloride; The molar ratio of thiourea, molybdenum source, and tin source is 6:0.25~0.5:1~1.5; The temperature of the first-step hydrothermal reaction is 200-240℃, and the time is 10-15 hours.

4. The method for preparing the all-solid-state sodium ion selective electrode according to any one of claims 1-3, characterized in that: Includes the following steps: (1) The SnS2-MoS2 heterojunction material was ultrasonically dispersed in water to prepare a dispersion; (2) The dispersion is drop-coated onto the pretreated electrode substrate, left to stand and dry naturally to form an ion-electron transduction layer on the surface of the electrode substrate; (3) The sodium ion selective membrane liquid is drop-coated onto the ion-electron transconductance layer, and then left to stand and dry naturally to obtain the all-solid sodium ion selective electrode.

5. The method of claim 4, wherein: The concentration of the dispersion in step (1) is 8-20 mg / mL; The electrode substrate includes a glassy carbon electrode, a screen-printed electrode, or a gold electrode; The pretreatment of the electrode substrate in step (2) includes alcohol wiping, polishing, ultrasonic cleaning and drying.

6. The preparation method according to claim 4, characterized in that: In step (3), the sodium ion selective membrane solution is obtained by mixing sodium ion carrier II, high molecular polymer, plasticizer and lipophilic macromolecule, dissolving in a solvent and then stirring.

7. The method of claim 4, wherein: The sodium ion selective membrane has a loading of 10-20 mg / cm² on the all-solid sodium ion selective electrode. 2 .

8. The method of claim 6, wherein: The polymer includes any one or more of polyvinyl chloride, polyvinyl acetate, and polymethyl methacrylate. The plasticizer includes any one or more of di-n-octyl sebacate, diisooctyl sebacate, 2-nitrophenyl octyl ether, and bis(2-ethylhexyl) sebacate. The lipophilic macromolecules include any one or more of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, potassium tetrakis(4-chlorophenyl)borate, potassium tetrakis(pentafluorophenyl)borate, and sodium tetraphenylborate; The solvent is tetrahydrofuran, cyclohexanone, methanol, or acetonitrile.

9. The application of the all-solid-state sodium ion selective electrode according to any one of claims 1-3, characterized in that: for detecting Na+ in solution + .

10. A wearable sensor, characterized by: The wearable sensor includes the all-solid-state sodium ion selective electrode as described in any one of claims 1-3.

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